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DIAZINON

Hazardous Substances DataBank Number
303
Related PubChem Records
Related CIDs

1 Human Health Effects

1.1 Toxicity Summary

IDENTIFICATION: Diazinon is a clear colorless liquid with a faint ester-like odor. Diazinon is soluble in most organic solvents. It is stable in neutral media, but is slowly hydrolyzed in alkaline media and more rapidly in acid media. Diazinon is a contact organophosphorus insecticide with a wide range of insecticidal activity. It is also available in mixed formulations with other insecticides. Another major use is as a drug in veterinary medicine. HUMAN EXPOSURE: Environmental levels of diazinon are generally low. The routes of exposure for the general population are inhalational and dietary. Exposure through water is negligible. Occupational exposure is primarily dermal. Several cases of accidental or suicidal poisoning by diazinon hae been reported, some of which were fatal. In some of these the cholinergic syndrome may have been more severe than expected because of the presence of highly toxic impurities such as TEPP. In certain cases, acute reversible pancreatitis was associated with a severe cholinergic syndrome. Reported cases of poisoning after occupational exposure have always been associated with the presence of impurities. ANIMAL STUDIES: The acute oral, dermal and inhalational toxicity is low. Short-term and long-term studies in mice, rats, rabbits, dogs and monkeys have shown that the only effect of concern is dose-related inhibition of acetyl cholinesterase activity. Diazinon is slightly irritant to rabbit skin but not to the eye. Diazinon is not a dermal sensitizer. Reproductive and developmental studies have revealed no evidence of embryotoxic or teratogenic potential. There was no effect on reproductive performance at dose levels that were not toxic to the parent animals. Mutagenicity studies with various end-points in vivo and in vitro gave no evidence of a mutagenic potential. There is no evidence of carinogenicity in rats or mice. In the dog and guinea-pig, diazinon has been reported to cause acute pancreatitis; this is considered to be a species-specific effect. Diazinon may be absorbed from the gastrointestinal tract, through the intact skin and following inhalation. Diazinon is oxidized by microsomal enzymes to cholinesterase inhibiting metabolites such as diazoxon, hydroxydiazoxon and hydroxydiazinon.
World Health Organization/International Programme on Chemical Safety. Environmental Health Criteria 198 Diazinon . pp. 1-5, 7 (1998)

1.2 Evidence for Carcinogenicity (Complete)

Cancer Classification: Not Likely to be Carcinogenic to Humans
USEPA Office of Pesticide Programs, Health Effects Division, Science Information Management Branch: "Chemicals Evaluated for Carcinogenic Potential" (April 2006)
A4: Not classifiable as a human carcinogen.
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 23

1.3 Human Toxicity Excerpts (Complete)

/HUMAN EXPOSURE STUDIES/ Extensive use of organophosphorous pesticides (OP) by young men represents a public health problem. Toxicity of OP mainly results in neurotoxicity due to their oxygen analogues (oxons), formed during the OP oxidative activation. OP alter semen quality and sperm chromatin and DNA at different stages of spermatogenesis. Oxons are more toxic than the parent compounds; however, their toxicity to spermatogenic cells has not been reported. We evaluated sperm DNA damage by several OP compounds and their oxons in human spermatozoa from healthy volunteers incubated with 50-750 microM of methyl-parathion (MePA), methyl-paraoxon (MePO), chlorpyrifos (CPF), chlorpyrifos-oxon (CPO), diazinon (DZN) or diazoxon (DZO). All concentrations were not cytotoxic (evaluated by eosin-Y exclusion), except 750 microM MePO. Oxons were 15% to 10 times more toxic to sperm DNA (evaluated by the SCSA parameter, %DFI) than their corresponding parent compounds, at the following order: MePO>CPO=MePA>CPF>DZO>DZN, suggesting that oxon metabolites participate in OP sperm genotoxicity.
Salazar-Arredondo E et al; Reprod Toxicol 25 (4): 455-60 (2008)
/HUMAN EXPOSURE STUDIES/ The influence of three polymorphisms of PON1 on serum diazoxonase activity was investigated in 85 healthy volunteers. Serum activity was assessed in as close to physiological conditions as possible (at pH 7.4, 150 mM NaCl and 37 degrees C with 50 microM diazoxon as substrate) and by quantifying pyrimidinol formation using high-performance liquid chromatography. PON1 genotypes were determined by the polymerase chain reaction and restriction enzyme digestion. For PON1 Q192R, individuals with the RR genotype had the highest serum diazoxonase activity, in contrast to some previous reports where activity was determined under less physiological conditions. Activity was slightly reduced in individuals with the QR genotype and activity was reduced even further in those with the QQ genotype. For PON1 L55M, there was a significant decrease in mean enzyme activity from LL>LM>MM genotypes. The promoter polymorphism PON1 -108 C/T had only a slight effect on activity. Overall, intragenotype variation in PON1 activity was appreciably greater than the mean intergenotype differences. In conclusion, although there is a wide variation in activity in individuals both within and between genotypes, those individuals with a combination of Q and M alleles generally have a lower ability to detoxify diazoxon, which implies a potentially greater susceptibility to toxicity from diazinon.
O'Leary KA et al; Pharmacogenet Genomics. 15 (1): 51-60 (2005)
/HUMAN EXPOSURE STUDIES/ ... Two men developed "marked" inhibition of plasma cholinesterase as a result of five doses at the rate of about 0.025 mg/kg/day. However, a dosage of 0.05 mg/kg/day for a total of 28 days reduced plasma cholinesterase of three men by only 35-40%. In three other tests, each involving three or four men and lasting 32-43 days, dosages ranging from 0.02 to 0.03 mg/kg/day led to reductions of plasma cholinesterase activity of 0, 15-20, and 14%, respectively
Hayes, W.J., Jr., E.R. Laws, Jr., (eds.). Handbook of Pesticide Toxicology. Volume 2. Classes of Pesticides. New York, NY: Academic Press, Inc., 1991., p. 1052
/HUMAN EXPOSURE STUDIES/ Four healthy males weighing between 74 & 96 kg & aged between 30 & 45 yr ingested diazinon in gelatin capsules (95.4% pure) at a dose of 0.025 mg/kg per day. Two males received 34 consecutive treatments (Group B), while the two other volunteers were treated for 4 days, were left untreated for the next 5 days in order to investigate reversibility of the effects & then received the capsules again for 32 more days (Group A). The daily dose was split into three admin taken after meals around 9, 13 & 19 hr. Parameters of hematology, urine analysis & blood biochemistry (plasma & erythrocyte cholinesterase, serum alkaline & acidic phosphatase activities) were determined at regular intervals. A reversible decr of plasma cholinesterase activity was observed in group A during the first 4 days of treatment while the erythrocyte cholinesterase activity remained unaffected. During the second treatment period of group A & during the entire treatment of group B, the cholinesterase activities were similar to those observed at pretest. No clinical signs or changes in other parameters were noted. It was concluded that the admin daily dose of 0.025 mg/kg marginally inhibited the plasma cholinesterase only, & can therefore be considered as a NOAEL in humans.
WHO; Environ Health Criteria 198: Diazinon p.74-75 (1998)
/HUMAN EXPOSURE STUDIES/ We present data on semen quality in partners of 493 pregnant women recruited through prenatal clinics in four US cities during 1999-2001. Sperm concentration, semen volume and motility were determined at the centres and morphology was assessed at a central laboratory. While between-centre differences in sperm morphology and sample volume were small, sperm concentration and motility were significantly reduced in Columbia, MO (MO) relative to men in New York, NY, Minneapolis, MN and Los Angeles, CA; total number of motile sperm was 113 x 10(6) in MO and 162, 201 and 196 x 10(6) in CA, MN and NY respectively. Differences among centres remained significant in multivariate models that controlled for abstinence time, semen analysis time, age, race, smoking, history of sexually transmitted disease and recent fever (all p-values <0.01). /Researchers/ hypothesized that poorer sperm concentration and motility in MO men relative to other centres might be related to agricultural pesticides that are commonly used in the mid-west. We investigated this hypothesis by conducting a nested case-control study within the MO cohort. We selected 25 men in this cohort for whom all semen parameters (concentration, % normal morphology and % motile) were low as cases and an equal number of men for whom all semen parameters were within normal limits as controls. We measured metabolites of eight non-persistent, current-use pesticides in urine samples the men had provided at the time of semen collection. Pesticide metabolite levels were elevated in cases compared with controls for the herbicides alachlor and atrazine, and for the insecticide diazinon (2-isopropoxy-4-methyl-pyrimidinol) (p-values for Wilcoxon rank test = 0.0007, 0.012, and 0.0004 for alachlor, atrazine and diazinon respectively). Men with higher levels of alachlor or diazinon were significantly more likely to be cases than men with low levels [odds ratios (OR) = 30.0, 16.7 for alachlor and diazinon respectively], as were men with atrazine over the limit of detection (OR = 11.3).
Swan SH; Int J Androl. 29 (1): 62-8 (2006)
/SIGNS AND SYMPTOMS/ SYMPTOMATOLOGY: NAUSEA IS OFTEN FIRST SYMPTOM, FOLLOWED BY VOMITING, ABDOMINAL CRAMPS, DIARRHEA, EXCESSIVE SALIVATION, ... HEADACHE, GIDDINESS, VERTIGO & WEAKNESS. RHINORRHEA & SENSATION OF TIGHTNESS IN CHEST ARE COMMON IN INHALATION EXPOSURES. BLURRING OR DIMNESS OF VISION, MIOSIS, ... TEARING, CILIARY MUSCLE SPASM, LOSS OF ACCOMMODATION & OCULAR PAIN, ... MYDRIASIS ... SOMETIMES SEEN ... PROBABLY DUE TO SYMPATHO-ADRENAL DISCHARGE. LOSS OF MUSCLE COORDINATION, SLURRING OF SPEECH, FASCICULATIONS & TWITCHING OF MUSCLES (PARTICULARLY OF TONGUE & EYELIDS), & GENERALIZED PROFOUND WEAKNESS. MENTAL CONFUSION, DISORIENTATION & DROWSINESS.
Gosselin, R.E., R.P. Smith, H.C. Hodge. Clinical Toxicology of Commercial Products. 5th ed. Baltimore: Williams and Wilkins, 1984., p. III-340
/SIGNS AND SYMPTOMS/ Symptoms associated with diazinon poisoning have been weakness, headache, tightness in the chest, blurred vision, nonreactive pinpoint pupils, salivation, sweating, nausea, vomiting, diarrhea, abdominal cramps, slurred speech, and moist rales in the lungs.
American Conference of Governmental Industrial Hygienists. Documentation of the Threshold Limit Values and Biological Exposure Indices. 5th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, 1986., p. 172
/CASE REPORTS/ A man survived subcutaneous injection of diazinon at a rate of about 14 mg/kg ... However, diazinon caused sweating, abdominal pain, nausea, and, in one instance, coma when 80 mg of active ingredient (in the form of a 1% solution) was applied to the skin of each of two men for control of creeping eruption ... . This strong reaction to a dosage of about 1.1 mg/kg is inconsistent with the other reports, especially those involving nonfatal illness following ingestion or subcutaneous injection. Thus, the diazinon used for therapy may have undergone change to a more toxic material. This was certainly the case in connection with a formulation responsible for intoxication of three applicators and a herd of cattle. The material was found to be 30 times more toxic than a recently formulated emulsion concentrate of equivalent concentration ... .
Hayes, W.J., Jr., E.R. Laws, Jr., (eds.). Handbook of Pesticide Toxicology. Volume 2. Classes of Pesticides. New York, NY: Academic Press, Inc., 1991., p. 1052
/CASE REPORTS/ A 26-year-old man, who ingested approximately 230 ml of a solution of an unknown concentration of diazinon in a suicide attempt, developed a severe cholinergic syndrome which was relieved by atropine and 2-PAM. Diuresis was greatly reduced (22 ml/h) and urine was dark and cloudy (specific gravity 1.029).
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/CASE REPORTS/ Three-week-old twins were hospitalized because of respiratory distress. One was cyanotic on admission, but both had rapid shallow breathing, profuse nasal and bronchial secretions, and pinpoint pupils; muscle fasciculations were not detectable. At 48 h only the sicker twin had slightly reduced pseudocholinesterase activity. Treatment was appropriate and recovery uneventful. Investigation revealed that the babies lived in one side of a two-story house that had been divided into two apartments by partitions. About 10:30 h on the previous day the other apartment had been sprayed with 1% diazinon for cockroach control using approved spot applications directed mainly at cracks. The twins were the only ones who had remained indoors. The observed degree of respiratory distress in the presence of little or no inhibition of cholinesterase was consistent with exclusively respiratory exposure.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/CASE REPORTS/ Inappropriate indoor spraying with a 25% concentrate of diazinon (intended for use only outdoors and only after dilution) led to the poisoning of 8 members of 2 related families. Children who ate oatmeal and used utensils contaminated by such use became ill and were hospitalized with symptoms of profuse sweating, nausea, vomiting and abdominal cramps. All were asymptomatic 24 hours after treatment with atropine. A 54 year old woman committed suicide by ingesting 1/2 pint of Ferti-Lome bag worm spray, calculated to have contained 22 g diazinon.
Gosselin, R.E., R.P. Smith, H.C. Hodge. Clinical Toxicology of Commercial Products. 5th ed. Baltimore: Williams and Wilkins, 1984., p. II-294
/CASE REPORTS/ One accident involved eight elderly men who drank a solution of diazinon they mistook for wine. Three of them, with an average of 73 years, died ... . In another instance, nine men survived the consumption of a beverage they prepared with diazinon emulsion concentrate as one ingredient.
Hayes, W.J., Jr., E.R. Laws, Jr., (eds.). Handbook of Pesticide Toxicology. Volume 2. Classes of Pesticides. New York, NY: Academic Press, Inc., 1991., p. 1052
/CASE REPORTS/ A formerly completely healthy 43 year old farm worker was brought to hospital by his wife and his employer because of insomnia the night before and sudden loss of memory during the morning. He was found to have flushing of the abdominal wall; a firm, regular, nontender liver enlarged 2-3 cm below the costal margin; and a cholinesterase level only 33% of normal. By next morning he appeared completely recovered. His only known recent exposure to pesticides involved handling diazinon containers a day or two before admission, but there had been no recognized accident and no episode of typical cholinergic illness ... .
Hayes, W.J., Jr., E.R. Laws, Jr., (eds.). Handbook of Pesticide Toxicology. Volume 2. Classes of Pesticides. New York, NY: Academic Press, Inc., 1991., p. 1052
/CASE REPORTS/ A woman drank diazinon and cut her wrists. Although the relative importance of poisoning and blood loss as causes of death is unclear, it is of interest that the following concentrations of unmetabolized diazinon were reported in the tissues: brain, 0.3 ppm; liver, 0.08 ppm; kidney, 0.04 ppm; and lung, 0.015 ppm ... .
Hayes, W.J., Jr., E.R. Laws, Jr., (eds.). Handbook of Pesticide Toxicology. Volume 2. Classes of Pesticides. New York, NY: Academic Press, Inc., 1991., p. 1052
/CASE REPORTS/ Two patients, treated dermally with diazinon for control of a parasitic infestation, were seriously poisoned by a dosage of about 1.1 mg/kg according to Hayes. In contrast, a man, who had received an oral dosage of 250 mg diazinon/kg, recovered following treatment that included gastric lavage. In a series of five tests, each involving two to four men, oral doses of diazinon at the rate of 0.05 mg/kg/day for a total of 28 days reduced plasma cholinesterase activity by 35%-40% but did not affect the red cell enzyme. A dosage of 0.02 mg/kg/day for 37 days reduced plasma cholinesterase activity by only 14% an amount difficult to distinguish from normal variation.
American Conference of Governmental Industrial Hygienists, Inc. Documentation of the Threshold Limit Values and Biological Exposure Indices. 6th ed. Volumes I, II, III. Cincinnati, OH: ACGIH, 1991., p. 389
/CASE REPORTS/ A 12 wk old infant girl developed persistent hypertonicity of the extremities without other signs of intoxication. It was discovered that the organophosphate insecticide diazinon was applied in her home 5 weeks prior to the onset of signs. Six months after application, high levels of diazinon residues were found on the floor (230 ng/cm), in vacuum cleaner dust (1700 mg/kg), & in the air (2.8 ng/cu m). A diazinon dose of approx 0.02 mg/kg per day was calculated & derived from the infant's urine level of diazinon metabolites determined 6 months after application of diazinon in her home. Her muscle tone returned to normal shortly after the infant was removed from the home.
WHO; Environ Health Criteria 198: Diazinon p.74 (1998)
/EPIDEMIOLOGY STUDIES/ Cholinesterase activity measurements for 542 California agricultural pesticide applicators under medical supervision during the first 9 mo of 1985 were analyzed. Medical records of applicators were used if the subject had been exposed for over 3 hr in a 30 day period to category organophosphate or carbamate pesticides. Employers of all workers with cholinesterase activity depressions that fell to 70% or less of the workers's plasma or RBC baselines were contacted to obtain a list of pesticides handled in the 2-wk interval preceding the greatest reported cholinesterase activity depression. Diazinon usage in California for 1985 was 694,700 lb. The frequency of diazinon by % of baseline to depress cholinesterase activity was 1 for plasma (< 50% reduction) and 4 and 2 for RBC (< 70% and 60% reductions, respectively).
Ames RG et al; Am J Ind Med 15 (2): 143-50 (1989)
/GENOTOXICITY/ ... STUDY ON EFFECT OF DIAZINON ON MITOSIS IN HUMAN LYMPHOCYTES REPORTED CHROMOSOMAL ABERRATIONS IN 74% OF CELLS at 0.5 MG/ML. DOSAGE OF 25 MG/ML PRODUCED GREATER EFFECT ON MITOSIS THAN 0.5 & 5.0 MG/ML.
National Research Council. Drinking Water & Health Volume 1. Washington, DC: National Academy Press, 1977., p. 611

/GENOTOXICITY/

Table: Special Studies on the mutagenicity of Diazinon In vitro

Test System (In vitro)
Sister chromatid exchange study
Test object
Human lymphoid cells (LAZ-007)
Results
Negative
Test System (In vitro)
Sister chromatid exchange study
Test object
Whole blood human lymphocytes
Results
Equivocal
Test System (In vitro)
Chromosomal aberration
Test object
Human lymphocytes
Results
Questionable
Test System (In vitro)
Chromosomal aberrations
Test object
Human lymphocytes
Results
Negative

WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/ALTERNATIVE and IN VITRO TESTS/ The NTera2/D1 (NT2) cell line, which was derived from a human teratocarcinoma, exhibits properties that are characteristics of a committed neuronal precursor at an early stage of differentiation. ... NT2 cells exposed to the OP insecticide diazinon at concentrations ranging between 10(-4) and 10(-5)M showed a time-dependent enhancement of cell death. When exposed at 10(-6)M diazinon showed higher cell viability than control samples up to 72 hr, followed by a decreasing phase. The cell death caused by the exposures showed a number of features characteristic of apoptosis, including membrane and mitochondrial potential changes. ...
Aluigi MG et al; Chem Biol Interact. 187 (1-3): 299-303 (2010)
/ALTERNATIVE and IN VITRO TESTS/ Preconfluent cultures of normal rat intestinal cells (IEC-6 cell line) and normal human colonic epithelial cells were treated with 0.05-50 muM doses of atrazine, diazinon, and endosulfan. After 3 days of treatment, the change in cell proliferation was quantified by cell counting or the MTT growth assay. Both intestinal and colonic epithelial cell cultures had increases in cell growth when treated with as little as 1.0 muM atrazine, diazinon, or endosulfan. The observed changes in both cultured intestinal and colonic cell growth rates were not due to the influence of the vehicle control dimethyl sulfoxide (DMSO). That is, the treatment of the cell cultures with concentrations of dimethyl sulfoxide as high as 0.5% for 3 days resulted in no change in cell growth compared with untreated control cultures. A consistent observation with all three of the compounds was that the highest doses (50 muM) had the least "proliferative potential" in stimulating either IEC-6 cell or human colonic epithelial cell growth. Within the concentration range used, none of the herbicides or pesticides caused a decrease in cell proliferation below that of the untreated control cultures. Overall, treatment of IEC-6 cell cultures with atrazine, diazinon, or endosulfan produced a biphasic growth response, whereas the same treatment in the human colonic epithelial cell cultures produced a more sustained level of growth over the same period.
Greenman SB et al; Environmental Research 75 91): 85-93 (1997)

1.4 Human Toxicity Values (Complete)

0.02 MG/KG/DAY IS A NO-EFFECT LEVEL IN MAN.
Hayes, Wayland J., Jr. Pesticides Studied in Man. Baltimore/London: Williams and Wilkins, 1982., p. 387

1.5 Skin, Eye, and Respiratory Irritations

A skin and severe eye irritant.
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127

1.6 Medical Surveillance (Complete)

Determination of RBC and Serum (Plasma) Cholinesterase Levels. BAT for acetylcholinesterase inhibitors (sampling time is end of exposure or end of shift, or for long-term exposures sampling time is after several shifts: both measured as acetylcholinesterase in erythrocytes): reduction of activity to 70% of reference value. BEI (sampling time is discretionary): 70% of individual's baseline.
Ryan, R.P., C.E. Terry (eds.). Toxicology Desk Reference 4th ed. Volumes 1-3. Taylor & Francis, Washington, D.C. 1997., p. 954
Renal Function Tests /include/ ... Urine Albumin ... Urinary Beta-2-Microglobulin and/or Retinal Binding Protein (RBP) ... Urinary Alpha and Pi Isoenzymes of Glutathione S-Transferase ... Urinary Enzyme N-Acetylglucosaminidase ... /and/ Routine Urinalysis.
Ryan, R.P., C.E. Terry (eds.). Toxicology Desk Reference 4th ed. Volumes 1-3. Taylor & Francis, Washington, D.C. 1997., p. 955
Respiratory Symptom Questionnaires: Questionnaires have been published by the American Thoracic Society and the British Medical Research Council. These questionnaires have been found to be useful in identification of people with chronic bronchitis, however certain pulmonary function tests such as FEV1 have been found to be better predictors of chronic airflow obstruction.
Ryan, R.P., C.E. Terry (eds.). Toxicology Desk Reference 4th ed. Volumes 1-3. Taylor & Francis, Washington, D.C. 1997., p. 956

1.7 Average Daily Intake (Complete)

FOOD INTAKE: 1969-82 (estimate): 0.0082 ug/kg body wt/day(1-7).
(1) Gartrell MJ et al; J Assoc Off Anal Chem 68: 862-75 (1985)
(2) Duggan RE et al; Pest Res Levels in Foods in the United States From July 1, 1969 to June 30, 1976; Washington, DC FDA Div Chem Technol (1983)
(3) Johnson RD et al; J Assoc Off Anal Chem 67: 154-66 (1984)
(4) Podrebarac DS; J Assoc Off Anal Chem 67: 176-85 (1984)
(5) Johnson RD et al; Pest Monit J 15: 39-50 (1981)
(6) Johnson RD et al; J Assoc Off Anal Chem 67: 145-54 (1984)
(7) Podrebarac DS; J Assoc Off Anal Chem 67: 166-75 (1984)
The average daily intake of diazinon(1), determined from the FDA's Total Diet Study (1986-1991), is as follows for age/sex groups (ug/kg body wt/day): 6-11 mo (0.0061); 2 yr (0.0106); 14-16 yr female (0.0037); 14-16 yr male (0.0052); 25-30 yr female (0.0033); 25-30 male (0.0037); 60-65 female (0.0031); 60-65 yr male (0.0034). The mean air exposure to diazinon in Jacksonville, FL and Springfield, MA was 1,380 and 158 ng/day, respectively(2).
(1) USFDA; Food and Drug Administration Pesticide Program - Residue Monitoring 1992. J AOAC Int 76: 127A-148A (1993)
(2) Whitemore RW et al; Arch Environ Contam Toxicol 26: 47-59 (1994)

1.8 Reported Fatal Dose

The estimated adult oral fatal dose is approximately 25 g.
Ellenhorn, M.J. and D.G. Barceloux. Medical Toxicology - Diagnosis and Treatment of Human Poisoning. New York, NY: Elsevier Science Publishing Co., Inc. 1988., p. 1071
Estimated adult oral fatal dose is approximately 25 g.
Ellenhorn, M.J. and D.G. Barceloux. Medical Toxicology - Diagnosis and Treatment of Human Poisoning. New York, NY: Elsevier Science Publishing Co., Inc. 1988., p. 1071

2 Emergency Medical Treatment

2.1 Antidote and Emergency Treatment (Complete)

Airway protection. Insure that a clear airway exists. Intubate the patients and aspirate the secretions with a large-bore suction device if necessary. Administer oxygen by mechanically assisted pulmonary ventilation if respiration is depressed. Improve tissue oxygenation as much as possible before administering atropine, so as to minimize the risk of ventricular fibrillation. In severe poisonings, it may be necessary to support pulmonary ventilation mechanically for several days. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 40
Atropine sulfate. Administer atropine sulfate intravenously, or intramuscularly if intravenous injection is not possible. Remember that atropine can be administered through an endotracheal tube if initial IV access is difficult to obtain. Depending on the severity of poisoning, doses of atropine ranging from very low to as high as 300 mg/day may be required, or even continuous infusion. The objective of atropine antidotal therapy is to antagonize the effects of excessive concentrations of acetylcholine at end-organs having muscarinic receptors. Atropine does not reactivate the cholinesterase enzyme or accelerate disposition of organophosphate. Recrudescence of poisoning may occur if tissue concentrations of organophosphate remain high when the effect of atropine wears off. Atropine is effective against muscarinic manifestations, but it is ineffective against nicotinic actions, specifically muscle weakness and twitching, and respiratory depression. Despite the limitations, atropine is often a life-saving agent in organophosphate poisonings. Favorable response to a test dose of atropine (1 mg in adults, 0.01 mg/kg in children under 12 years) can help differentiate poisoning by anticholinesterase agents from other conditions. However, lack of response, with no evidence of atropinization (atropine refractoriness) is typical of more severe poisonings. The adjunctive use of nebulized atropine has been reported to improve respiratory distress, decrease bronchial secretions, and increase oxygenation. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 41
Glycopyrolate has been studied as an alternative to atropine and found to have similar outcomes using continuous infusion. Ampules of 7.5 mg of glycopyrolate were added to 200 ml of saline and this infusion was titrated to the desired effects of dry mucous membranes and heart rate above 60 beats/min. During this study, atropine was used as a bolus for a heart rate less than 60 beats/min. The other apparent advantage to this regimen was a decreased number of respiratory infections. This may represent an alternative when there is a concern for respiratory infection due to excessive and difficult to control secretions, and in the presence of altered level of consciousness where the distinction between atropine toxicity or relapse of organophosphate poisoning is unclear. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 41
Pralidoxime. Before administration of pralidoxime, draw a blood sample (heparinized) for cholinesterase analysis (since pralidoxime tends to reverse the cholinesterase depression). Administer pralidoxime (Protopam, 2-PAM), a cholinesterase reactivator, in cases of severe poisoning by organophosphate pesticides in which respiratory depression, muscle weakness, and/or twitching are severe. When administered early (usually less than 48 hours after poisoning) pralidoxime relieves the nicotinic as well as the muscarinic effects of poisoning. Pralidoxime works by reactivating the cholinesterase and also by slowing the "aging" process of phosphorylated cholinesterase to a non-reactivatable form. ... Dosage of pralidoxime may be repeated in 1-2 hours, then at 10-12 hour intervals if needed. In very severe poisonings, dosage rates may be doubled. Repeated doses of pralidoxime are usually required. In cases that involve continuing absorption of organophosphate (as after ingestion of large amounts), or continuing transfer of highly lipophilic organophosphate from fat into blood, it may be necessary to continue administration of pralidoxime for several days beyond the 48 hour post-exposure interval usually cited as the limit of its effectiveness. ... Blood pressure should be monitored during administration because of the occasional occurrence of hypertensive crisis. Administration should be slowed or stopped if blood pressure rises to hazardous levels. Be prepared to assist pulmonary ventilation mechanically if respiration is depressed during or after pralidoxime administration. If intravenous injection is not possible, pralidoxime may be given by deep intramuscular injection. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 41
Skin decontamination. In patients who have been poisoned by organophosphate contamination of skin, clothing, hair, and/or eyes, decontamination must proceed concurrently with whatever resuscitative and antidotal measures are necessary to preserve life. Flush the chemical from the eyes with copious amounts of clean water. If no symptoms are evident in a patient who remains alert and physically stable, a prompt shower and shampoo may be appropriate, provided the patient is carefully observed to insure against any sudden appearance of poisoning. If there are any indications of weakness, ataxia, or other neurologic impairment, clothing should be removed and a complete bath and shampoo given while the victim is recumbent, using copious amounts of soap and water. Attendants should wear rubber gloves as vinyl provides no protection against skin absorption. Surgical green soap is excellent for this purpose, but ordinary soap is about as good. Wash the chemical from skin folds and from under fingernails. Contaminated clothing should be promptly removed, bagged and laundered before returning. Contaminated leather shoes /SRP: and other leather items/ should be discarded. Note that the pesticide can contaminate the inside surfaces of gloves, boots, and headgear. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 43
Gastrointestinal decontamination. If organophosphate has been ingested in quantities probably sufficient to cause poisoning, consideration should be given to gastrointestinal decontamination ... . If the patient has already vomited, which is most likely in serious exposures, further efforts at GI decontamination may not be indicated. In significant ingestions, diarrhea and/or vomiting are so constant that charcoal adsorption and catharsis are not indicated. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 44
Observation. Observe patient closely for at least 72 hours to ensure that symptoms (sweating, visual disturbances, vomiting, diarrhea, chest and abdominal distress, and sometimes pulmonary edema) do not recur as atropinization is withdrawn. In very severe poisonings by ingested organophosphates, particularly the more lipophilic and slowly hydrolyzed compounds, metabolic disposition of toxicant may require as many as 5-14 days. In some cases, this slow elimination may combine with profound cholinesterase inhibition to require atropinization for several days or even weeks. As dosage is reduced, the lung bases should be checked frequently for crackles. If crackles are heard, or if there is a return of miosis, bradycardia, sweating, or other cholinergic signs, atropinization must be re-established promptly. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 44
Furosemide may be considered if pulmonary edema persists in the lungs even after full atropinization. It should not be used until the maximum benefit of atropine has been realized. Consult package insert for dosage and administration. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 44
Pulmonary ventilation. Particularly in poisonings by large ingested doses of organophosphate, monitor pulmonary ventilation carefully, even after recovery from muscarinic symptomatology, to forestall respiratory failure. In some cases, respiratory failure has developed several days following organophosphate ingestion, and has persisted for days to weeks. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 44
Hydrocarbon aspiration may complicate poisonings that involve ingestion of liquid concentrates of organophosphate pesticides. Pulmonary edema and poor oxygenation in these cases will not respond to atropine and should be treated as a case of acute respiratory distress syndrome. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 44
Cardiopulmonary monitoring. In severely poisoned patients, monitor cardiac status by continuous ECG recording. Some organophosphates have significant cardiac toxicity. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 44
Seizure control. Rarely, in severe organophosphate poisonings, convulsions occur despite therapy with atropine and pralidoxime. Insure that causes unrelated to pesticide toxicity are not responsible: head trauma, cerebral anoxia, or mixed poisoning. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 45
Contraindications. The following drugs are contraindicated in nearly all organophosphate poisoning cases: morphine, succinylcholine, theophylline, phenothiazines, and reserpine. Adrenergic amines should be given only if there is a specific indication, such as marked hypotension. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 45
Re-exposures. Persons who have been clinically poisoned by organophosphate pesticides should not be re-exposed to cholinesterase inhibiting chemicals until symptoms and signs have resolved completely and blood cholinesterase activities have returned to at least 80 percent of pre-poisoning levels. If blood cholinesterase was not measured prior to poisoning, blood enzyme activities should reach at least minimum normal levels before the patient is returned to a pesticide contaminated environment. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 45
Do not administer atropine or pralidoxime prophylactically to workers exposed to organophosphate pesticides. Prophylactic dosage with either atropine or pralidoxime may mask early signs and symptoms of organophosphate poisoning and thus allow the worker to continue exposure and possibly progress to more severe poisoning. Atropine itself may enhance the health hazards of the agricultural work setting: impaired heat loss due to reduced sweating and impaired ability to operate mechanical equipment due to blurred vision. This can be caused by mydriasis, one of the effects of atropine. /Organophosphate pesticides/
U.S. Environmental Protection Agency/Office of Prevention, Pesticides, and Toxic Substances. Reigart, J.R., Roberts, J.R. Recognition and Management of Pesticide Poisonings. 5th ed. 1999. EPA Document No. EPA 735-R-98-003, and available in electronic format at: https://www.epa.gov/pesticides/safety/healthcare, p. 45
The objective of this work was to determine optimal treatment regimens for organophosphate (OP) or carbamate insecticide toxicoses in fowl using the antidotes atropine sulfate & pralidoxime chloride (2-PAM). Broiler chicks in treatment groups, each comprising 3 replicates of 6-7 birds/replicate, were gavaged on a body weight (BW) basis with the OP & carbamate insecticides, diazinon & methomyl, respectively, at lethal dosages. Treatment groups were injected with either or both of the antidotes at various dosages as soon as clinical signs appeared. Birds appearing healthy 24 hr thereafter were regarded as having been treated successfully. At a dosage of 100 mg/kg BW, atropine was mildly toxic & at 200 mg/kg 2-PAM was severely toxic (but not lethal), whereas at dosages of 50 & 100 mg/kg BW, respectively, the antidotes were at their most effective. With diazinon, atropine alone was only partially effective (12/20 survivors), whereas 2-PAM was extremely efficacious (20/20 survivors); the combination of the 2 antidotes at 2 dosages was slightly less effective (19/20 survivors) than 2-PAM alone. For methomyl toxicity, atropine was largely successful (18/20 survivors), whereas 2-PAM was mostly unsuccessful (10/20 survivors); the combination at high dosage was less effective (15/20 survivors) than atropine alone, but at a low dosage the combination was the most successful (20/20 survivors). The results indicate that anticholinesterase insecticide toxicoses in fowl should not be treated according to textbook recommendations, & antidotal dosage with atropine should be up to 100 times greater than is commonly recommended. The specific cause of the toxicoses should ideally be determined before treatment is given, but as this is often unknown, a combination of antidotes may be the optimal treatment protocol.
SHLOSBERG A et al; VETERINARY AND HUMAN TOXICOLOGY 39 (6): 347-350 (1997)
Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Organophosphates and related compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 294
Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Aggressive airway control may be needed. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Organophosphates and related compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 294
Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously and consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Administer atropine. Correct hypoxia before giving atropine ... . Administer pralidoxime chloride (2 PAM). USE UNDER DIRECT PHYSICIAN ORDERS ONLY ... . Treat seizures with adequate atropinization and correction of hypoxia. In rare cases diazepam or lorazepam may be necessary ... . Watch for signs of fluid overload ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Organophosphates and related compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 294-5

3 Animal Toxicity Studies

3.1 Non-Human Toxicity Excerpts (Complete)

/LABORATORY ANIMALS: Acute Exposure/ ... /Investigators/ gave diazinon (DZN) to newborn rats on postnatal days 1-4, using doses (0.5 or 2 mg/kg) spanning the threshold for barely detectable cholinesterase inhibition. We then evaluated the lasting effects on indices of neural cell number and size, and on functional markers of acetylcholine (ACh) synapses (choline acetyltransferase, presynaptic high-affinity choline transporter, nicotinic cholinergic receptors) in a variety of brain regions. DZN exposure produced a significant overall increase in cell-packing density in adolescence and adulthood, suggestive of neuronal loss and reactive gliosis; however, some regions (temporal/occipital cortex, striatum) showed evidence of net cell loss, reflecting a greater sensitivity to neurotoxic effects of DZN. Deficits were seen in ACh markers in cerebrocortical areas and the hippocampus, regions enriched in ACh projections. In contrast, there were no significant effects in the midbrain, the major locus for ACh cell bodies. The striatum showed a unique pattern, with robust initial elevations in the ACh markers that regressed in adulthood to normal or subnormal values.
Slotkin TA et al; Environ Health Perspect. 116 (3): 340-8 (2008)
/LABORATORY ANIMALS: Acute Exposure/... /Investigators/ exposed neonatal rats to daily doses of diazinon on postnatal days 1-4, using doses (0.5 or 2mg/kg) spanning the threshold for barely-detectable cholinesterase inhibition. We then evaluated the effects on 5HT(1A) and 5HT(2) receptors, and on the 5HT transporter in cerebral cortical regions and the brainstem in adolescence through adulthood. Diazinon evoked a lasting deficit in 5HT(1A) receptors in males only, whereas it caused a small but significant increase in 5HT transporters in females; neither effect showed a significant regional selectivity. This pattern differed substantially from that seen in earlier work with another organophosphate, chlorpyrifos, which at pharmacodynamically similar doses spanning the threshold for cholinesterase inhibition, evoked a much more substantial, global upregulation of 5HT receptor expression; with chlorpyrifos, effects on receptors were seen in females, albeit to a lesser extent than in males, and were also regionally distinct. The effects of diazinon were nonmonotonic, showing larger alterations at the lower dose, likely reflecting positive trophic effects of cholinergic stimulation once the threshold for cholinesterase inhibition is exceeded. ...
Slotkin TA et al; Brain Res Bull. 75 (5): 640-7 (2008)
/LABORATORY ANIMALS: Acute Exposure/ ... The effect of DZN on glucose tolerance in genetic type 2 diabetic rats, Goto-Kakizaki (GK) rats. Oral glucose tolerance test (OGTT) (2g/(5 mL/kg)) was assessed before, and 1 and 2 weeks after intraperitoneal injection of DZN (6.5 mg/kg) in Wistar and GK rats /was investigated/. DZN significantly increased the levels of glucose in plasma at designated blood sampling points in GK rats. The activity of hepatic drug-metabolizing enzymes and expression of hepatic cytochrome P450 (CYP) 1A2, CYP3A2 and CYP2D1, which oxidize DZN to DZN-oxon, a potent ChE inhibitor, were measured before DZN injection. There were no significant differences in the activity and expression of CYPs between both rat groups, indicating that the ability of metabolic activation might be almost the same in Wistar and GK rats. DZN dramatically decreased the activity of cholinesterase (ChE) in plasma by approximately 40% in both Wistar and GK rats. However, no significant differences in the activity of ChE in plasma were observed between Wistar and GK rats for 5 days after DZN injection. No massive necrotic and apoptotic areas, leukocyte infiltration and immunoreactive insulin-positive cells (beta-cells) were observed in pancreas 2 weeks after DZN injection. Moreover, DZN might not affect plasma insulin levels in Wistar and GK rats.
Ueyama J et al; Toxicol Lett. 182 (1-3): 42-7 (2008)
/LABORATORY ANIMALS: Acute Exposure/ The effect of diazinon (DZN) on the activities of cholinesterase (ChE) in plasma and acetylcholinesterase (AChE) in erythrocyte and brain was investigated in normal and streptozotocin-induced diabetic rats. Hepatic drug-metabolizing enzyme activity was also estimated by measuring the systemic clearance of antipyrine, and the expression of hepatic cytochrome P450 (CYP) 3A2 and CYP1A2, which is closely related to the metabolism from DZN to DZN-oxon, a strong inhibitor of both ChE and AChE. No significant differences in the activities of ChE in plasma and AChE in erythrocyte were observed between normal and diabetic rats. Treatment with DZN significantly decreased these activities in diabetic rats more than in normal rats 6hr after injection (6.5 mg/kg). Treatment with DZN significantly decreased the activity of AChE in brain of diabetic rats than normal rats 3hr after injection (65 mg/kg), although no significant difference in the activity was found between normal and diabetic rats. The urinary recovery of diethylphosphate (DEP), a metabolite of DZN-oxon, was significantly increased in diabetic rats, but that of diethylthiophosphate (DETP), a metabolite of DZN, was unchanged. Significant increases in the systemic clearance of antipyrine and protein levels of hepatic CYP1A2, not CYP3A2, were observed in diabetic rats.
Ueyama J et al; Toxicol Lett. 170 (3): 229-37 (2007)
/LABORATORY ANIMALS: Acute Exposure/ Diazinon (88% purity) was administered by gavage to 15 rats per sex and dose at single doses of 0, 2.5, 150, 300 and 600 mg/kg. Three, 9 or 24 hr after dosing, five animals of each group were bled for determination of serum and red blood cell cholinesterase activity and then killed for determination of CNS cholinesterase activity. There was no mortality. Signs of cholinergic poisoning, e.g., salivation, diarrhoea and muscle fasciculations, were observed in animals of both sexes dosed at 300 and 600 mg/kg. Clinical signs first appeared 3 hr after treatment. Maximum observable toxicity was noted 9 hr after treatment in males and 24 hr after treatment in females. Serum cholinesterase activity was significantly decreased at all time points in all groups treated with 2.5 mg/kg or more. Maximum inhibition was observed 9 hr after dosing, and values remained depressed at 24 hr after dosing. Red blood cell cholinesterase activity was significantly inhibited at all time intervals in animals of both sexes treated with >150 mg/kg. Again, maximum inhibition was observed 9 hr after dosing, and activity remained depressed at 24 hr after dosing. In addition, a significant inhibition of red blood cell cholinesterase activity was noted in females dosed with 2.5 mg/kg diazinon 9 hr after dosing. Cerebellum, cerebral cortex, striatum, hippocampus and thoracic spinal cord cholinesterase activities were decreased in female rats dosed with >150 mg/kg at all three time points. Cerebellum, striatum and hippocampus cholinesterase activities were decreased in male rats dosed with >150 mg/kg at all three time intervals, whereas cerebral cortex and thoracic spinal cord cholinesterase activities were decreased in male rats dosed with >150 mg/kg at 9 and 24 hr after dosing. The NOAEL for inhibition of brain cholinesterase activity was 2.5 mg/kg for both sexes.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/LABORATORY ANIMALS: Acute Exposure/ ... RETICULOCYTOPENIA AND A HIGH MYELOID TO ERYTHROID RATIO WERE FOUND IN SOME /LAB/ ANIMALS KILLED IN LESS THAN A MONTH BY LARGE, REPEATED, ORAL DOSES. THE RATIO WAS GREATER THAN 100:1 IN DOGS RECEIVING 20 MG/KG/DAY. IT WAS NOT INDICATED THAT THESE CHANGES WERE RELATED TO THE CAUSE OF DEATH, BUT NONFATAL DOSES DID NOT PRODUCE THEM.
Hayes, Wayland J., Jr. Pesticides Studied in Man. Baltimore/London: Williams and Wilkins, 1982., p. 385
/LABORATORY ANIMALS: Acute Exposure/ The dermal toxicity of 5 organophosphate insecticides was investigated with a mouse intermittent self exposure model. Blood cholinesterases were monitored on days 3 and 1 before exposure and for 4-6 days during exposure to foliar residues. Responses were greater in unmuzzled than in muzzled animals due to oral contamination. After two 10 hr exposures, muzzled mice showed log linear cholinesterase responses across a wide range of foliar pesticide concn. Foliar pesticide levels that caused 50% depression in plasma or red blood cell cholinesterase were determined. The greatest responses for emulsifiable concentrate (ec) and encapsulated formulations were found with diazinon, followed by parathion and methyl parathion.
Skinner CS, Kilgore WW; J Toxicol Environ Health 9 (3): 461-82 (1982)
/LABORATORY ANIMALS: Acute Exposure/ Effect of temperature on diazinon induced acute toxicity was investigated in female albino rats. Diazinon (40 mg/kg, ip) significantly reduced the cholinesterase activity of the brain, produced hyperglycemia and reduced the glycogen content of cerebral and peripheral tissues. The activity of glycogen phosphorylase in both the tissues was significantly increased while hexokinase activity was enhanced only in the brain. Succinate dehydrogenase activity was inhibited in both the tissues and level of the blood lactate was increased. In animals kept in high temperature (40 °C) the changes were reduced as compared to the animals kept at room temperature (30 °C).
Husain K, Mirza MA; Biol Mem 15 (2): 84-9 (1989)
/LABORATORY ANIMALS: Acute Exposure/ ... The effects of diazinon exposure on some physiological and biochemical parameters, as well as, histopathological changes and histochemical acetyl-cholinesterase activity (AChE) /were investigated/. The red Baladi rabbits were dipped into water (Control Group), diazinon at low concentrations of 0.6 mg diazinon low concentration (DLC) or high concentration of 3 mg diazinon high concentration (DHC) dissolved in 1L of water for 10 sec. Treatment was repeated after 10 days and animals were sacrificed between 0 and 21 days after the second treatment. Blood analysis revealed that Red blood cells (RBC's), hemoglobin (Hb) and plasma total protein (TP) were significantly decreased in both diazinon concentrations (P<0.01), (P<0.05), (P<0.01) respectively. Cholesterol and microsomal protein were increased (P<0.01), while, liver/ body weight and cytochrome P-450 were decreased in both concentrations (P<0.01). Also there was a highly significant effect of concentration X day interaction on all parameters (P<0.01). Histopathological changes of liver, kidney and brain were observed after DHC dipping. Glycogen content was decreased in liver and increased in kidney Bowman's capsule. Furthermore, AChE activity was inhibited in brain tissue, decreased in liver cells, but gradually increased in kidney glomerular cells. Therefore, kidney and brain were highly affected by diazinon exposure compared with the liver. Exposure of animals to diazinon caused extensive changes in physiological, biochemical, and histopathological parameters as well as histochemical AChE. ...
Yehia MA et al; Exp Toxicol Pathol 59 (3-4): 215-25 (2007)
/LABORATORY ANIMALS: Acute Exposure/ ... The behavioral effects and potential for inhibition of acetyl cholinesterase of diazinon (MG87%) was assessed in Sprague-Dawley Crl:CDRBR/VAF/Plus strain rats. .. Four groups of 5 rats/sex were dosed with 0, 100, 250 or 500 mg/kg of diazinon (undiluted) and additional groups of females were dosed with 25 or 50 mg/kg and the rats observed for clinical signs for 14 days. At 100 mg/kg, females were noted to have one incident of hypoactivity. At 250 and/or 500 mg/kg, miosis, hypoactivity, fur staining, and/or loss of pain reflex and at 500 mg/kg there was one death. These findings were corroborated by the cholinesterase inhibition part of the study which also demonstrated miosis at 100 mg/kg in a single male rat. ... The LOAEL was 250 mg/kg based on miosis and hypoactivity. The NOAEL was 100 mg/kg, but this is considered a threshold dose level.... Seven groups of males were dosed as control, 0.05, 0.5, 1, 10, 100 or 500 mg/kg and seven groups of females were dosed as control, 0.05, 0.12, 0.25, 2.5, 25 or 250 mg/kg and sacrificed approximately 24 hours later. Observations on their behavior reactions were noted and the blood and brain were assessed for cholinesterase and acetyl cholinesterase inhibition. ... Plasma cholinesterase was inhibited at 2.5 mg/kg in females (61%) and at 10 mg/kg in males (44%). Red blood cell acetyl cholinesterase was inhibited at 25 mg/kg in females (35%) and at 100 mg/kg in males (49%). Brain acetyl cholinesterase was inhibited at 25 mg/kg in females (36%, not significant) and at 250 mg/kg (70%) and at 500 mg/kg in males (69%). ... The LOAEL was 2.5 mg/kg based on 61% plasma cholinesterase inhibition in females, and the NOAEL was 0.25 mg/kg.
USEPA; Diazinon: Diazinon Aggregate Human Health Risk Assesment. Document ID: EPA-HQ-OPP-2008-0351-0005 p. 30 (April 12, 2000). Available from, as of September 2, 2011: https://www.regulations.gov/#!home
/LABORATORY ANIMALS: Acute Exposure/ Chlorpyrifos (CPF) and diazinon (DZN) are thionophosphorus organophosphate (OP) insecticides; their toxicity is mediated through /cytochrome P450/ (CYP) metabolism to CPF-oxon and DZN-oxon, respectively. Conversely, CYPs also detoxify these OPs to trichloropyridinol (TCP) and 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP), respectively. In addition, A-esterase (PON1) metabolism of CPF- and DZN-oxon also forms TCP and IMHP. This study evaluated the role intestinal and hepatic metabolism may play in both the activation and detoxification of CPF and DZN in Sprague-Dawley rats. Similar CYP- and PON1-mediated metabolic profiles were demonstrated in microsomes from liver or isolated intestinal enterocytes. The metabolic efficiency was estimated by calculating the psuedo-1st order rate constant from the metabolic constants by dividing Vmax/Km. In enterocyte microsomes, the CYP metabolic efficiency for metabolism to the oxon metabolites was approximately 28-fold greater for CPF than DZN. Compared on a per nmol P450 basis, the Vmax for CPF in enterocytes was approximately 2-3 times higher than in liver microsomes for the production of CPF-oxon and TCP. The Michaelis-Menten rate constant (Km) for the metabolism of CPF to CPF-oxon was comparable in liver and enterocyte microsomes; however, the enterocyte Km for TCP production was higher (indicating a lower affinity). The smaller volume of intestine, lower amount of CYP, and higher Km for TCP in the enterocyte microsomes, resulted in a lower catalytic efficiency (2 and 62 times) than in liver for oxon and TCP. PON1-mediated metabolism of CPF- and DZN-oxon was also demonstrated in liver and enterocyte microsomes. Although PON1 affinity for the substrates was comparable in hepatic and enterocytic microsomes, the Vmax were 48- to 275-fold higher, in the liver.
Poet TS et al; Toxicol Sci. 72 (2): 193-200 (2003)
/LABORATORY ANIMALS: Acute Exposure/ A housefly colony collected at a sanitary land-fill was selected with diazinon for several generations in the laboratory. The resultant strain was 1400-fold resistant to diazinon (LD50: 50 ug per fly) when compared to the susceptible CSMA strain. It had increased activity in each of the three enzyme systems involved in detoxification. Cytochrome p450 dependent monoxygenases catalyzed diazinon degradation, producing diethyl phosphorothioic acid and diethyl phosphoric acid. Glutathione transferase mediating dealkylation and deakylation reactions degraded both diazinon and diazonon. Phosphorotriester hydrolase activity for diazinon was detected only in the resistant strain and was present in all the subcellular fractions examined. The activity was highest in the soluble fraction. The resistant strain also showed a decreased sensitivity to inhibition at the site of action, AChE. Interstrain comparison in AChE sensitivity using diazoxon as the inhibitor revealed a 6-fold difference in the bimolecular rate constant ki. An extremely high resistance of this housefly strain to diazinon may be attributable to a synergistic effect of multiple factors.
Oi M et al; J Pestic Sci 15 (2): 217-24 (1990)
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... Treatment of rats with diazinon significantly enhances renal lipid peroxidation which is accompanied by a decrease in the activities of renal antioxidant enzymes (e.g. catalase, glutathione peroxidise, glutathione reductase, glucose-6-phosphate dehydrogenase, glutathione S-transferase) and depletion in the level of glutathione reduced. In contrast, the activities of renal gamma-glutamyl transpeptidase and quinone reductase were increased. Parallel to these changes, diazinon treatment enhances renal damage as evidenced by sharp increase in blood urea nitrogen and serum creatinine. ... Diazinon treatment eventuates in decreased renal glutathione reduced, a fall in the activities of antioxidant enzymes including the enzymes involved in glutathione metabolism and excessive production of oxidants with concomitant renal damage, all of which are involved in the cascade of events leading to diazinon-mediated renal oxidative stress and toxicity. ...
Shah MD, Iqbal M; Food Chem Toxicol. 48 (12): 3345-53 (2010)
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... The effect of crocin and safranal was studied against subacute toxicity of diazinon (DZN) on hematological and genotoxicity indices in rats. Rats were divided into 16 groups consisted of 6 rats in control, diazinon, vitamin E, vitamin E and DZN, crocin (3 doses), crocin (3 doses) and DZN, safranal (3 doses), safranal (3 doses) and DZN groups. Vitamin E (200 IU/kg), safranal at doses 0.025, 0.05 and 0.1 mL/kg and crocin at doses 50, 100 and 200 mg/kg were injected intraperitoneally to rats three times per week alone or with DZN (20 mg/kg/day, orally) for 4 weeks. Hematological parameters were evaluated at the end of 4 weeks. Evaluation of genotoxicity was done using the micronucleus assay. Vitamin E and, at lower doses, safranal (0.025 and 0.05 mL/kg) and crocin (50 mg/kg) restored the reduction of red blood cell, hemoglobin and hematocrit indices induced by DZN. These agents at some doses also prevented the reduction in platelets counts indices in diazinon treated group. A significant increase in reticulocyte was induced by diazinon. Vitamin E, safranal (0.025 or 0.05 mL/kg) and all doses of crocin decreased this effect of diazinon. In all doses vitamin E, crocin and safranal did not inhibit the effect of diazinon on RBC cholinesterase activity. A significant increase in micronucleus indices was seen with diazinon. Vitamin E, safranal and crocin could not prevent this genotoxicity.
Hariri AT et al; Phytomedicine. 18 (6): 499-504 (2011)
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... 12 albino Wistar rats weighting between 220-280 g were divided into two experimental groups, as follow, control group and diazinon treated group. The effects of diazinon, on rat interstitial cell testosterone production, blood factors and plasma glucose levels were evaluated. Male rats were treated orally with a single dose of 1/4 LD50 of diazinon. Animals received treatment for 28 days. Present results indicated that in diazinon treated group, plasma glucose and testosterone levels increased compared to control. Also in diazinon group, reduce of blood factors were observed than control. ... Diazinon disturbs the synthesis of testosterone and glucose release from liver into blood and it led to anemia.
Alahyary P et al; Pak J Biol Sci. 11 (1): 127-30 (2008)
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... Sprague-Dawley strain rats (four groups of 15/sex) were dosed as control, 0.1, 1, 10 and 100 ug/L of diazinon MG-8 (87% purity) for six hours/day 7 days/week in a 21-day inhalation study. No systemic effects (symptoms) were reported in response to treatment. ... At 0.1 ug/L, plasma cholinesterase (ChE) was inhibited in males (30%, p < 0.05) and females (56%, p <0.05). Progressively higher levels of inhibition were noted at higher doses. Red blood cell cholinesterase was inhibited in males (18%, p < 0.05) at 0.1 ug/L and inhibition was progressively greater at higher doses. In females red blood cell cholinesterase was statistically inhibited (45%) at 1 ug/L. At 1 ug/L brain acetyl cholinesterase was inhibited in both males (13%, p < 0.05) and females (15%, p < 0.05). The LOAEL is < 0.1 ug/L (converts to 0.026 mg/kg/day) and is based on plasma cholinesterase inhibition in male and female rats, and red blood cell cholinesterase inhibition in males. The NOAEL was <0.1 ug/L for plasma ChE and RBC ACHE in males, but was > 0.1 ug/L for RBC AChE in females and brain AChE in both sexes. A definitive NOAEL for cholinesterase inhibition was not determined. The LOAEL and NOAEL for systemic effects were both > 100 ug/L.
USEPA; Diazinon: Diazinon Aggregate Human Health Risk Assesment. Document ID: EPA-HQ-OPP-2008-0351-0005 p. 26 (April 12, 2000). Available from, as of September 2, 2011: https://www.regulations.gov/#!home
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... 5 groups of 4/sex beagles dosed with diazinon (MG-8) at dose levels of 0, 0.1, 0.5, 150 or 300 ppm for 13 weeks. These doses correspond to 0.0034/0.0037, 0.020/0.021, 5.9/5.6 or 10.9/11.6 mg/kg/day for males/females. Plasma cholinesterase was inhibited in females at 0.5 ppm at approximately 16% (not significant) and in males at approximately 30% (p < 0.05). At 150 ppm, plasma cholinesterase was inhibited about 80% in both males and females. At 150 ppm, red blood cell (approximately 25% in males and approximately 31% in females, p < 0.01) and brain acetyl cholinesterase (31% in males and 30% in females) were inhibited. At 300 ppm, brain AChE was inhibited approximately 42% in males and 45% in females. The systemic LOAEL is 5.6 mg/kg/day based on deceased body weight. The NOAEL is 0.021 mg/kg/day. Systemic effects were noted at 150 ppm and included decreased body weight gain in females (34%, not significant), total protein (approximately 1.4%) and calcium (approximately 5%). At 300 ppm, both male and female body weight gain was decreased (33% males and 45% females), and decreased food consumption and total protein and calcium deceases were increased. The LOAEL was 0.020 mg/kg/day based on plasma cholinesterase inhibition in males, and the NOAEL was 0.0037 mg/kg/day. ...
USEPA; Diazinon: Diazinon Aggregate Human Health Risk Assesment. Document ID: EPA-HQ-OPP-2008-0351-0005 p. 25 (April 12, 2000). Available from, as of September 2, 2011: https://www.regulations.gov/#!home
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... Five groups of 4/sex beagle dogs dosed with diets containing 0, 0.5, 2, 20 or 500 ppm diazinon (MG-8) /for 4 weeks/. These dose levels corresponded to 0.02/0.023, 0.073/0.082, 0.80/0.75 or 14.68/15.99 mg/kg/day for males/females. Plasma cholinesterase was inhibited at 0.5 ppm in females at approximately 29%, (p < 0.01) and in males at approximately 8% (not significant). Only at 500 ppm was red blood cell (26-39% in both males and females) and brain (44% in males, 50% in females) acetyl cholinesterase inhibited (all p < 0.01). Systemic toxicity was evident at 500 ppm only and included emesis and decreased body weight and feed consumption. The LOAEL for systemic toxicity was 14.68 mg/kg/day based on body weight effects. The NOAEL was 0.80 mg/kg/day. The LOAEL was < 0.023 mg/kg/day based on plasma cholinesterase inhibition. ...
USEPA; Diazinon: Diazinon Aggregate Human Health Risk Assesment. Document ID: EPA-HQ-OPP-2008-0351-0005 p. 25 (April 12, 2000). Available from, as of September 2, 2011: https://www.regulations.gov/#!home
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... Diazinon (99.2% purity) fed to rats for 4 weeks at doses up to 25 mg/kg diet produced no visible toxic manifestations such as tremors or hyperexcitability. Feeding diazinon 25 mg/kg diet for 30 days produced more significant reduction of cholinesterase activity in plasma (by 22-30%) and brain (by 5-9%) among treated females than among males. Erythrocyte acetylcholinesterase activity was significantly more depressed (by 13-17%) in treated females than in males at days 21-28 of the feeding trial. The greater degree of cholinesterase inhibition in females was possibly attributable to the higher amount of diazinon ingested by females than by males after day 15 of the study.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Male and female CD-1 mice were dosed with 0 or 200 ppm diazinon for duration of 2 or 4 weeks (20/sex/exposure duration). /Diazinon/ (FL 872049, 87.7%) was pre-pared in diet, adjusted for purity. ... No effects on mortality, clinical signs, body weight, or food consumption. ... /Cholinesterase/ (ChE) effects were substantial: RBC ChE inhibition was 44-48% in males, 58-61% in females. Plasma ChE inhibition was 97% in males, and 98% in females. Brain ChE inhibition at days 16 and 30, respectively, was 28 and 38% for males, and 21 and 37% for females. ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.4 (April 15, 1999). Available from, as of August 30, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ DOGS FED DIAZINON AT 0.25, 0.75, & 75 PPM IN DIET FOR 90 DAYS. ... RED-CELL CHOLINESTERASE WAS DECR ONLY IN HIGHEST-DOSAGE GROUP, & PLASMA CHOLINESTERASE WAS DECR IN 2 HIGHER GROUPS.
National Research Council. Drinking Water & Health Volume 1. Washington, DC: National Academy Press, 1977., p. 610
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Male and female rats receiving 100 and 1000 ppm (weight) technical Diazinon in the diet for 4 weeks showed no gross signs of intoxication, alteration of growth, or gross pathology at autopsy. Red blood cells and brain cholinesterase levels were significantly inhibited at both dosages.
Clayton, G.D., F.E. Clayton (eds.) Patty's Industrial Hygiene and Toxicology. Volumes 2A, 2B, 2C, 2D, 2E, 2F: Toxicology. 4th ed. New York, NY: John Wiley & Sons Inc., 1993-1994., p. 727
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Diazinon (97.1% pure) was suspended in 50% aqueous polyethylene glycol 300 & topically admin under semiocclusive dressing to groups of 5 male & 5 female albino rabbits at daily doses of 0, 1, 5 & 100 mg/kg bw for 5 days/wk for 3 wk. In the highest dose group, four males treated at 100 mg/kg died during the first wk of treatment. Consequently, the dose was reduced to 50 mg/kg. Clinical signs were observed in the highest dose group & included anorexia, ataxia, fasciculations, tremors, diarrhea, hypoactivity, hypotonia & salivation. Most of the signs disappeared after the dose was reduced. Mild dermal reactions were noted at site of test substance admin. body weight gain & food consumption was similar in all groups, & most laboratory parameters remained unaffected by the treatment. Reduced cholinesterase activities were found in serum, red blood cells & the brain in animals treated at > or =5 mg/kg. In the highest-dose group, the reductions were significant for brain, red blood cells & serum cholinesterase activities, while with 5 mg/kg there was a statistically significant decr of activity in the brain cholinesterase of females only. In the highest-dose animals, the histopathological exam showed a slight hyperkeratosis of the skin at the site of treatment. The NOEL was considered to be 1 mg/kg, based on inhibition of brain cholinesterase.
WHO; Environ Health Criteria 198: Diazinon p.53-54 (1998)
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ ... In a carcinogenicity toxicity study diazinon (98% purity) was administered to 50/sex B63CF1 strain mice in their diets at dose levels of 100 or 200 ppm (estimated to be 14 and 29 mg/kg/day for 103 weeks. The control group consisted of 25/sex untreated mice. No systemic toxicity. ... At the doses tested, there was no evidence of carcinogenicity related to treatment with diazinon. The LOAEL for systemic effects was > 29 mg/kg/day.
USEPA; Diazinon: Diazinon Aggregate Human Health Risk Assesment. Document ID: EPA-HQ-OPP-2008-0351-0005 p. 26 (April 12, 2000). Available from, as of September 2, 2011: https://www.regulations.gov/#!home
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Diazinon /was given at/ doses of 0, 400, and 800 ppm in feed to 50/sex Fischer F344 rats in treated groups and 25/sex in concurrent controls. No neoplasia, and no adverse effects indicated. ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.4 (April 15, 1999). Available from, as of August 30, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Diazinon, FL 872049, 87.7% purity, was fed at initial dietary concentrations of 0, 0.1, 0.5, 150, or 300 ppm to 4 beagles/sex/dose level /for 52 weeks/. After 14 wk, the diet for the 300 ppm group was reduced to 225 ppm for the balance of the study, due to marked bw gain decrements. Mean dose levels were 0.0032, 0.015, 4.7, and 7.7 mg/kg/day for males; and 0.0037, 0.020, 4.5, and 9.1 mg/kg/day for females. NOEL (other than cholinesterase inhibition) = 0.5 ppm (decreased bw in 150 ppm males and in 300/225 ppm males and females: decreased food consumption in both sexes at 150 and 300/225 ppm). Cholinesterase inhibition NOEL = 0.1 ppm in males and marginally < 0.1 ppm in females (statistically significant reductions in serum cholinesterase activity compared to concurrent controls at two out of four intervals in females at 0.1 ppm). At 150 and 300/225 ppm, serum and RBC cholinesterase activities were significantly reduced in both sexes, and brain cholinesterase activity was significantly reduced in females. ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.2 (April 15, 1999). Available from, as of August 30, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Diazinon (MG-8), (FL 872049), 87.7% purity, was administered in diets of CD rats at dose levels of 0, 0.1, 1.5, 125, or 250 ppm for 1 yr (10 rats/sex/group) or up to 99 wk (20 rats/sex/group). An additional control group received a stabilizer (which is present in technical diazinon) at a level comparable to that which is present in treated diet at the 250 ppm diazinon level. ... NOEL for cholinesterase inhibition = 0.1 ppm (about 50% inhibition of serum cholinesterase in females at 1.5 ppm, generally less inhibition in males). The NOEL for RBC or brain cholinesterase inhibition was 1.5 ppm. Inhibition of brain cholinesterase was 42 and 48% at 99-week study termination in 250 ppm males and females, respectively. NOEL for other effects = 250 ppm ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.2 (April 15, 1999). Available from, as of August 30, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ RATS FED FOR 10 MONTHS ON DIETS CONTAINING UP TO 65 PPM SHOWED NO GROSS TOXIC SYMPTOMS. IT IS HIGHLY TOXIC TO BEES.
Martin, H. and C.R. Worthing (eds.). Pesticide Manual. 4th ed. Worcestershire, England: British Crop Protection Council, 1974., p. 164
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ ... EIGHT-MO STUDY IN WHICH DIAZINON WAS ADMIN BY GELATIN CAPSULE /TO DOGS/ DAILY at 2.5, 5.0, 10.0, & 20.0 MG/KG. ... 3 OF DOGS at HIGHEST DOSAGE DIED IN 1ST MO; 1 OF DOGS at 10.0 MG/KG DEVELOPED CHOLINERGIC SYMPTOMS ... . THERE WERE NO DOSE-DEPENDENT HEMATOLOGIC EFFECTS at ANY DOSAGE.
National Research Council. Drinking Water & Health Volume 1. Washington, DC: National Academy Press, 1977., p. 611
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ ... Levels of Evidence of Carcinogenicity: Male Rats: Negative; Female Rats: Negative; Male Mice: Negative; Female Mice: Negative.
Bioassay Diazinon for Possible Carcinogenicity (1979) Technical Rpt Series No. 137 DHEW Pub No. (NIH) 79-1392, U.S. Department of Health Education and Welfare, National Cancer Institute, Bethesda, MD 20014
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Rats received 10, 100, and 1000 ppm (weight) active Diazinon as a wettable powder in the diet for 72 weeks with no apparent gross signs of toxicity. Dogs received orally various doses of active Diazinon as a wettable powder for 46 weeks. No pathology, gross or microscopic, was observed at the lowest dosage [4.6 mg/(kg)(day)] in 2 weeks. After 12 weeks cholinesterase inhibition was complete at the lowest dosage. At a dosage of 9.3 mg/kg(day) for 5 weeks signs of toxicity and complete cholinesterase inhibition were observed. Withdrawal of Diazinon at the highest dosage resulted in reversal of signs and regeneration of cholinesterase activity to normal limits after 2 weeks.
Clayton, G.D., F.E. Clayton (eds.) Patty's Industrial Hygiene and Toxicology. Volumes 2A, 2B, 2C, 2D, 2E, 2F: Toxicology. 4th ed. New York, NY: John Wiley & Sons Inc., 1993-1994., p. 726
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Rats tolerated 50 mg/kg/day for 72 weeks without illness but with complete inhibition of red cell cholinesterase and marked inhibition of brain cholinesterase. Rats that received 10, 100, or 1000 ppm of active diazinon as a wettable powder for 72 weeks had no apparent gross signs of toxicity.
American Conference of Governmental Industrial Hygienists, Inc. Documentation of the Threshold Limit Values and Biological Exposure Indices. 6th ed. Volumes I, II, III. Cincinnati, OH: ACGIH, 1991., p. 389
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Dogs dosed at 4.6 mg/kg/day for 46 weeks showed no gross signs of toxicity but had an inhibited cholinesterase activity within 12 weeks. Dogs promptly lost weight and showed signs of poisoning and complete cholinesterase inhibition when given 9.3 mg/kg/day. ... /It was/ found that monkeys were poisoned at a dosage of 5 mg/kg/day administered over 2 years.
American Conference of Governmental Industrial Hygienists, Inc. Documentation of the Threshold Limit Values and Biological Exposure Indices. 6th ed. Volumes I, II, III. Cincinnati, OH: ACGIH, 1991., p. 389
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Pigs were orally admin diazinon in capsules at doses of 0, 1.25, 2.5, 5 & 10 mg/kg body weight daily for periods of up to 8 months. ...Mortality & cholinergic signs of poisoning were evident at 2.5 mg/kg body weight per day.
WHO; Environ Health Criteria 198: Diazinon p.52 (1998) https://www.inchem.org/pages/ehc.html
/LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity/ Groups of 3 male & 3 female Rhesus monkeys received initial daily doses of 0, 0.1, 1.0, & 10 mg diazinon/kg bw, admin by gastric intubation. After 34 days the doses were lowered to 0, 0.5, & 5.0 mg/kg & after 106 weeks of treatment the study was terminated. Mortality was similar in all dose groups... . Clinical signs included tremor in the highest-dose group animals & an incr incidence of soft stools was noted at 1.0 & 10.0 mg/kg. In comparison to the controls, all treated animals gained slightly less weight. Treatment-related deviations in the lab parameters examined were limited to reductions of cholinesterase activities. At the 0.5 mg/kg dose level, the erythrocyte cholinesterase activity was occasionally reduced in some animals & plasma cholinesterase activity was consistently depressed. At the highest-dose level, plasma & erythrocyte cholinesterase activities were markedly inhibited & the brain cholinesterase activity was reduced in one monkey. The postmortem exams revealed no changes of toxicological relevance.
WHO; Environ Health Criteria 198: Diazinon p.56 (1998) https://www.inchem.org/pages/ehc.html
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ THE MECHANISM BY WHICH ORGANOPHOSPHATE INSECTICIDES, INCLUDING DIAZINON, CAUSE MICROMELIA IN EMBRYONIC CHICK LIMBS WAS EXAMINED USING A TISSUE CULTURE APPROACH. THERE WAS NO OBVIOUS CORRELATION BETWEEN EITHER THE TERATOGENICITY OR TOXICITY OF THE INSECTICIDE IN OVO & THE INHIBITION OF PROLIFERATION & CHONDROGENESIS IN VITRO.
BYRNE DH, KITOS PA; BIOCHEM PHARMACOL 32 (19): 2881-90 (1983)
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ In the present study, we tested the ability of diazinon (DZN) to alter sperm chromatin by phosphorylating nuclear protamines. Mice were injected with a single dose of DZN (8.12 mg/kg, i.p.), and killed 8 and 15 days after treatment. Quality of sperm from epididymis and vas deferens was evaluated through standard methods and chromatin condensation by flow cytometry (DNA Fragmented Index parameters: DFI and DFI%) and fluorescence microscopy using chromomycin-A(3) (CMA(3)). Increases in DFI (15%), DFI% (4.5-fold), and CMA(3) (2-fold) were observed only at 8 days post-treatment, indicating an alteration in sperm chromatin condensation and DNA damage during late spermatid differentiation. In addition, an increase of phosphorous content (approximately 50%) in protamines, especially in the phosphoserine content (approximately 73%), was found at 8 days post-treatment. Sperm viability, motility, and morphology showed significant alterations at this time. These data strongly suggest that spermatozoa exposed during the late steps of maturation were the targets of DZN exposure. The correlation observed between the phosphorous content in nuclear protamines with DFI%, DFI, and CMA(3) provides evidence that phosphorylation of nuclear protamines is involved in the OP effects on sperm chromatin.
Pina-Guzman B et al; Toxicol Appl Pharmacol. 202 (2): 189-98 (2005)
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ ... Pregnant female Sprague-Dawley rats were given diazinon orally at doses of 0, 1.9, 3.8, and 7.6 mg/kg body weight (bw)/day on gestation days 6 to 15. Maternal brain acetylcholinesterase activities, measured on gestation day 20, were significantly decreased at 3.8 and 7.6 mg/kg bw/day, but fetal acetylcholinesterase activity was not altered. Maternal toxicities, as evidenced by cholinergic symptoms including diarrhea, tremors, weakness, salivation, and decreased activities, were observed at the 3.8 and 7.6 mg/kg bw/day dose groups. Net gravid uterine weight was decreased at a dose of 7.6 mg/kg bw/day. No maternal effects were apparent in the 1.9 mg/kg bw/day dose group. Maternal toxicity at a dose of 3.8 mg/kg bw/day did not induce fetotoxicity or teratogeneicity. However, 7.6 mg/kg bw/day doses significantly resulted in fetal toxicity and malformations in addition to maternal toxicity in animals. ...
Elmazoudy RH et al; Birth Defects Res B Dev Reprod Toxicol 92 (6): 534-42 (2011)
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ Diazinon, 89.2%, was administered to New Zealand White rabbits by gavage on days 6 through 18 of gestation at 0, 7.0, 25.0 or 100 mg/kg/day; 19-22/group. Maternal NOEL =25 mg/kg/day: mortality, 9/22, and increased clinical signs at 100 mg/kg/day. Developmental toxicity NOEL = 100 mg/kg/day, no effect on fetal parameters at any dose level. ... Mimimum. Maternal NOEL = 25 mg/kg, increased mortality; Fetal toxicity NOEL = 100 mg/kg (HDT); Teratogenic NOEL > 100 mg/kg (HDT)
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.7 (April 15, 1999). Available from, as of August 31, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ Diazinon technical, no purity stated, was administered to Crl.COBS CD (SD) (BR) rats by gavage on day 6 through 15 of gestation at 0, 10, 20 or 100 mg/kg/day to 27/group. No adverse effects indicated. Slight maternal toxicity (weight gain and food consumption) and developmental toxicity (structural changes) seen at 100 mg/kg/day. ... NOEL for maternal and developmental toxicity = 20 mg/kg/day. ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.6 (April 15, 1999). Available from, as of August 31, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ Diazinon, purity of 95%, was presented in the feed at concentrations of 0, 10, 100, and 1000 ppm, which were verified analytically. Parental rats were exposed for 13 and 26 weeks before their first and second mating trials, respectively, and were exposed for a total of 29-31 weeks before they were sacrificed. Exposure to Diazinon affected the reproductive performance of the rats in a manner that was dependent on dose as well as duration of exposure. Fecundity (number live deliveries/number cohoused) was decreased at the 1000 ppm treatment level for the F1a mating trial, and at the 10 ppm, 100 ppm and 1000 ppm treatment levels for the F1b mating trial. ... Occurrence of total litter resorptions in the Diazinon-treated groups, indicated by large bodyweight gains after mating, which were not followed by deliveries. Reproductive NOAEL < 10 ppm (decreased fecundity in the F1b trial). Parental effects included: prolonged durations of gestation followed in some cases by postbirthing tremors in the 1000 ppm dams; decreased gestational and lactational bodyweights and/or bodyweight gains in the 1000 ppm dams; and reduced absolute ovary weights and/or ovary weights relative to bodyweight in the 100 ppm and 1000 ppm dams. Parental NOAEL = 10 ppm (reduced ovary weights). Progeny effects included: decreased live litter sizes (each of the Diazinon-treated groups, both trials); increased incidences of stillbirths (1000 ppm group, both trials; 10 ppm group, F1b trial); and decreased pup survival and pup BWs during lactation (100 ppm and 1000 ppm groups, both trials). Progeny NOAEL < 10 ppm (decreased live litter size, both trials). ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.6 (April 15, 1999). Available from, as of August 31, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ Diazinon, purity of 95%, was presented in the feed at concentrations of 0, 10, 100, and 500 ppm, which were verified analytically. F0 rats and F1 rats, derived from F1a litters, were exposed for 10-11 weeks before their single mating trials and were exposed for a total of 16-21 weeks before they were sacrificed. F0 parental effects were limited to the high-dose group; ... lower gestational BW gains and lactational BWs. F1 high-dose males and dams weighed respectively 26% and 16% less than did the controls after weaning; males still weighed 15% less at mating and 14% less at termination; females weighed 6% less at mating but had BWs equal to those of the controls at termination. F1 mid-dose males weighed less and had gained less weight than the controls at mating. F1 dams weighed less than the controls at the start of their gestations and gained less weight during their gestational and lactational periods. ...Both F0 and F1 high-dose groups exhibited increased incidences of prolonged gestations (> 24 d). Progeny effects included: decreased live litter size for the high-dose F2a litters and decreased pup survival and pup BWs during lactation for the F1a mid- and high-dose groups and for the F2a high-dose group. Progeny NOEL = 10 ppm (decreased pup survival and post partum BWs). ... The incidence of total litter resorptions was increased in each of the Diazinon-treated groups in the F2a trial and the corresponding gestation index was decreased for each of the Diazinon-treated groups (reproductive NOEL < 10 ppm).
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.4 (April 15, 1999). Available from, as of August 30, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ Diazinon (94.9% pure) was administered in the feed to groups of 30 male and 30 female Sprague Dawley rats for 10 weeks prior to mating, throughout mating of the F0 animals and during two generations up to weaning and sacrifice of the F2 pups. The dietary concentrations used were 0, 10, 100 and 500 mg/kg. ... At 500 mg/kg there was an increase in the proportion of dams with prolonged gestation in both generations, and in the F1 animals there was a trend toward a decrease in the number of pregnancies and viable newborns and adverse effects on fertility indices. Mating behavior was unaffected by treatment. Litter size on lactation day 0 was decreased in both the F1 and F2 pups at 500 mg/kg, whereas pup weight and sex ratio on day 0 were comparable to controls for both generations. Decreases in pup survival and corresponding decreases in pup weight were observed in both generations at 500 mg/kg and in the F1 pups at 100 mg/kg. Compound-related clinical and necropsy observations were noted in some F1 pups at 500 mg/kg (tremor, no milk in stomach). NOAEL was 10 mg/kg diet for pups and parental animals.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ ... DIAZINON ... SLIGHTLY TERATOGENIC IN SHERMAN ... RAT, WHEN SINGLE DOSE WAS ADMIN IP ON DAY 11 OF GESTATION at DOSE WHICH CAUSED SEVERE TOXIC SYMPTOMS IN DAMS. ONLY ... DOSE LEVELS ... WHICH PRODUCED TOXIC SYMPTOMS IN DAMS AFFECTED FETUS; DECR FETAL BODY WT WAS MOST SENSITIVE INDICATOR ... .
The Chemical Society. Foreign Compound Metabolism in Mammals Volume 3. London: The Chemical Society, 1975., p. 657
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ THE 4E FORMULATION OF DIAZINON WAS ADMIN TO PREGNANT RATS BY GAVAGE ON DAYS 9, 10, 8-12, OR 12-15 OF GESTATION. ... PUPS WERE DELIVERED ... & EXAMINED FOR ABNORMALITIES. NONE WERE FOUND TO BE DOSE RELATED. ... HIGHER INCIDENCE OF URINARY MALFORMATIONS, HYDRONEPHROSIS & HYDROURETER ... IN MULTIPLE-DOSE ... THAN IN CONTROLS.
National Research Council. Drinking Water & Health Volume 1. Washington, DC: National Academy Press, 1977., p. 612
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ Diazinon is teratogenic to chick embryos when injected into the yolk sac before incubation or after 4 days of incubation at the rate of 1 mg/egg. The affected vertebral column is characteristically tortuous, shortened, and composed of abnormal vertebral bodies. In the neck region, these bodies have fused neural arches and lack most of the intervertebral joints
Hayes, W.J., Jr., E.R. Laws, Jr., (eds.). Handbook of Pesticide Toxicology. Volume 2. Classes of Pesticides. New York, NY: Academic Press, Inc., 1991., p. 1051
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ In rats, dosages (e.g., 95.2 mg/kg on day 9) that increased maternal mortality reduced fetal development as indicated by reduced weight of litters and mild "hydronephrosis" but caused no real teratogenic effect ... . A similar result was reported for intraperitoneal dosages of 100 and 150 mg/kg on day 11 ... . Repeated administration (40, 50, or 60 mg/kg/day) on days 7-19 of gestation reduced the growth of the dams but had no effect on the number of resorptions or corpora lutea, on litter size, or on fetal weight. Esterase activity of the fetal brain was reduced. A dosage of 75 mg/kg/day was fatal to dams in 4-5 days ... .
Hayes, W.J., Jr., E.R. Laws, Jr., (eds.). Handbook of Pesticide Toxicology. Volume 2. Classes of Pesticides. New York, NY: Academic Press, Inc., 1991., p. 1051
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ IN CHICK EMBRYOS, THE TERATOGENIC EFFECTS OF DIAZINON WAS INVESTIGATED IN REGARD TO SKELETAL DEVELOPMENT, PARTICULARLY OF THE EXTREMITIES & VERTEBRAE. DIAZINON (200 UG/EGG) INJECTED ON DAY 3, INHIBITED GROWTH OF THE FOLLOWING SKELETAL ELEMENTS: FEMUR, TIBIA, METATARSI & DIGITS OF THE LEG. THE INHIBITION WAS NOTICEABLE FROM THE 9TH DAY OF INCUBATION. THE GREATEST REDUCTION OF THE SKELETAL LENGTH WAS OBSERVED IN TIBIA & METATARSI & WAS CHARACTERIZED BY ANGULATIONS TOWARD THE DORSAL SIDE. IN THE CERVICAL REGION OF EMBRYOS TREATED WITH DIAZINON, UNIQUE DEFORMITIES SUCH AS AN UNDULATING NOTOCHORD & FUSED CERVICAL RINGS WERE SEEN AT AN EARLY STAGE (DAY 6). IT IS SUGGESTED THAT THE ORGANOPHOSPHATE-INDUCED MALFORMATIONS IN LEGS ARE MAINLY DUE TO GROWTH RETARDATION OF LATER STAGES OF DEVELOPMENT OF EACH SKELETAL ELEMENT. ON THE OTHER HAND, NECK DEFORMITIES RESULT FROM A PROFOUND ALTERATION OF DIFFERENTIATION AT EARLY STAGES OF DEVELOPMENT.
MISAWA M ET AL; J TOXICOL ENVIRON HEALTH 10 (4-5): 551-63 (1982)
/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ Diazinon was not teratogenic in rabbits receiving oral doses of 7 or 30 mg/kg during organogenesis. In hamsters, Diazinon was not teratogenic at dosage levels of 0.125 to 0.25 mg/kg. In the rabbit teratogenic effects were not seen at 30 mg/(kg)(day), but cholinergic effects were noted.
Clayton, G.D., F.E. Clayton (eds.) Patty's Industrial Hygiene and Toxicology. Volumes 2A, 2B, 2C, 2D, 2E, 2F: Toxicology. 4th ed. New York, NY: John Wiley & Sons Inc., 1993-1994., p. 726
/LABORATORY ANIMALS: Neurotoxicity/ Diazinon (88% purity) was administered by gavage one time to 15 Hsd: Sprague Dawley SD rats/sex/dose level. The dosing volume was 5 ml/kg. Dose levels were: 0 (corn oil), 2.5, 150, 300 and 600 mg/kg. ... Neurobehavioral testing using 10 rats/sex/dose was performed four times: pre-exposure; at the estimated time of peak effect (9-11 hr ... post dosing for Diazinon ... hereafter referred to as their peak times); approximately 7 days post dosing and approximately 14 days post dosing. Testing included a Functional Observation Battery (FOB) and automated assessments of motor activity in figure-8 mazes. Rats used in the FOB testing underwent perfusion fixation before being necropsied. In 5 rats/sex, from the negative control groups /and/ the 600 mg/kg Diazinon groups ... selected tissues were examined microscopically. Cage-side findings in both sexes on study days 1 or 2 included: reduced activity (LOEL= 300 mg/kg [males]); tremors; chromodacryorrhea; chromorhinorrhea; and pallor. Weekly bodyweight measurements were not affected whereas FOB body weights measured at 9-11 hr post dosing were statistically decreased for the groups (both sexes) dosed with Diazinon at > 300 mg/kg. Each of the five "functional categories" of the FOB testing had endpoints which were affected by Diazinon; these effects were seen only at the peak-time testing. Autonomic effects included: partially formed fecal pellets (LOEL = 2.5 mg/kg [males]); impaired respiration; increased lacrimation; increased salivation (males only); soiled fur; chromorhinorrhea; and chromodacryorrhea. Effects on muscle tone and equilibrium included: ataxic or abnormal gait (LOEL = 2.5 mg/kg [both sexes]); abnormal righting reflex; abnormal hind-limb extension; decreased forelimb and hind limb grip strengths; body twitch; and muscle fasciculations. The incidence of no reaction to tail pinching (a sensorimotor response) was increased in both sexes at 600 mg/kg. Endpoints concerning CNS activity and excitability that were affected included: reduced rearing activity (LOEL = 150 mg/kg [females]); reduced level of arousal; increased ease of handling; increased ease of removing from the cage; tremors; and the appearance of a stereotypic behavior involving opening and closing the mouth (LOEL = 150 mg/kg females). Physiological effects included: decreased bodyweight at peak time; and decreased rectal temperature (LOEL = 150 mg/kg females). ... Motor activity assayed at peak time was decreased by Diazinon, with LOELs of 150 mg/kg in the females and 300 mg/kg in the males. Inhibition of cholinesterase activity was seen at peak time, with LOELs of 2.5 mg/kg (serum, both sexes) and 150 mg/kg (RBC, both sexes). Only inhibition of RBC cholinesterase was seen in the testing done ~2 weeks post dosing; the LOELs were 150 mg/kg (females) and 300 mg/kg (males). Brain cholinesterase activity, which was only assayed ~2 weeks post dosing, was not affected. No effects were noted at necropsy or during the histological examination. ... Acute Neurotoxicity NOEL < 2.5 mg/kg (altered gait; partially formed feces); Overall Neurotoxicity NOAEL > 600 mg/kg (acute effects not present at 1 or 2 weeks post dosing). ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.18 (April 15, 1999). Available from, as of August 31, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Neurotoxicity/ Diazinon MG-8, purity 87%, was given by gavage on day 0 at 28.1 mg/kg to 18 domestic chicken hens. Due to a lack of effects, a second dosing was done on day 21, using 13.8 mg/kg. ... There were no signs of delayed neurotoxicity and neural tissues were unremarkable on microscopic examination. ...
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.18 (April 15, 1999). Available from, as of August 31, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
/LABORATORY ANIMALS: Neurotoxicity/ Choline, & the choline analogs monoethylcholine & N-aminodeanol were examined for prophylactic activity in acute acetylcholinesterase inhibitor toxicity in mice. The rank order of potency of the compounds was monoethylcholine > N-aminodeanol > choline. Simultaneous admin of monoethylcholine (60 mg/kg) or N-aminodeanol (200 mg/kg) with physostigmine reduced lethality to 17 & 13% respectively. Monoethylcholine (60 mg/kg) completely protected against diisopropylfluorophosphate & diazinon toxicity & N-aminodeanol reduced lethality to 17% for both agents. Choline (200 mg/ kg) exhibited only negligible antidotal activity against the inhibitors. In vitro concn of choline, monoethylcholine, & N-aminodeanol, similar to the estimated concn obtained in vivo in the acute toxicity study, produced mixed inhibition of mouse brain acetylcholinesterase. The inhibition was dose-related & was additive to the inhibition produced by the cholinesterase inhibitors. All three analogs reduced ligand binding at the nicotinic, M1, & M2 receptors. The rank order of potencies for the analogs at each receptor was nicotinic: (choline greater than monoethylcholine > N-aminodeanol), Ml; (Monoethylcholine greater than choline > N-aminodeanol), & M2: (Monoethylcholine > choline > N-aminodeanol). It is proposed that the analogs prevent acetylcholinesterase inhibitor toxicity peripherally by interacting with acetylcholinesterase, &/or by competing with acetylcholine for binding to cholinoceptors.
Patterson TA et al; Br J Pharmacol 97 (2): 451-60 (1989)
/ENDOCRINE MODULATION/ Treatment with diazinon (40 mg/kg, ip) resulted in hyperglycemia and depletion of glycogen from cerebral and peripheral tissues 2 hr after its administration in rats. The activities of the glycogenolytic enzymes glycogen phosphorylase and phosphoglucomutase were increased significantly in brain and liver, whereas that the glucose-6-phosphatase was not altered. The activities of the glycolytic enzymes hexokinase and lactate dehydrogenase were increased only in the brain. The cholinesterase activity of the brain was reduced by treatment with diazinon. The activities of the hepatic gluconeogenic enzymes fructose 1,6-diphosphatase and phosphoenolpyruvate carboxykinase were also increased significantly in diazinon-treated animals. The level of lactate was increased in brain and blood, whereas that of pyruvate was not changed. The activity of glucose-6-phosphate dehydrogenase was not changed significantly. The cholesterol and ascorbic acid contents of adrenals were depleted in diazinon-treated animals. The hyperglycemia and changes in carbohydrate metabolism were abolished by adrenalectomy, suggesting the possible involvement of the adrenals in the induced changes in diazinon-treated animals.
Matin MA et al; Biochem Pharmacol 39 (11): 1781-6 (1990)
/GENOTOXICITY/ The genetics of resistance to the organophosphate insecticide diazinon were investigated in four populations of the house fly, Musca domestica L, collected in the southern United States. Crosses were made between individual female of lines derived from each population and males of susceptible strain with three recessive mutants on chromosome II. Individual F1 females were crossed to mutant males, and the progenies were scored for resistance to diazinon and for presence of mutatnt phenotypes. A major chromosome II gene for resistance to diazinon was present in all populations at an overall frequency of 83%. Map distances between the resistance gene and the mutant aristapedia and between the mutants aristapedia and stubby wing were highly variable in all populations. Recombination among the visible mutants was usually reduced in resistant progenies relative to susceptible progenies. The data suggest that a single major gene for resistance to diazinon was present on chromosome II in all test populations at variable map positions and is usually associated with a chromosome rearrangement, probably an inversion. The results are similar to those obtained earlier with house fly populations selected for resistance to insecticides in the laboratory; therefore, they seem to be characteristic of field and laboratory populations of the house fly. Overall, the data offer an explanation, for previous results suggesting the existence of multiple, closely linked genes for metabolic resistance to insecticides on house fly chromosome II.
Cluck TW et al; J Econ Entomol 83 (1): 48-54 (1990)

/GENOTOXICITY/

Table: Special studies on the mutagenicity of Diazinon In vivo

Test System (In vivo)
Nucleus anomaly
Test Object
Chinese hamster bone marrow cells
Results
Negative
Test System (In vivo)
Micronucleus test
Test Object
Mouse bone marrow cells
Results
Negative
Test System (In vivo)
Dominant lethal study
Test Object
Mouse, male
Results
Negative
Test System (In vivo)
Chromosome aberrations
Test Object
Mouse spermatogonia
Results
Negative
Test System (In vivo)
Chromosome aberrations
Test Object
Mouse spermatocytes
Results
Negative
Test System (In vivo)
Chromosomal loss
Test Object
Drosophila melanogaster
Results
Negative
Test System (In vivo)
Sister chromatid exchange study
Test Object
Mouse bone marrow cells
Results
Negative

WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html

/GENOTOXICITY/

Table: Special Studies on the mutagenicity of Diazinon In vitro

Test System (In vitro)
Ames
Test object
Salmonella typhimurium TA98, TA100, TA1535, TA1537, TA1538; E. coli WP2 uvrA
Results
Negative
Test System (In vitro)
Ames
Test object
Salmonella typhimurium TA1535, TA1536, TA1537, TA1538
Results
Negative
Test System (In vitro)
Mouse lymphoma assay
Test object
Mouse lymphoma cells, L5178Y/tk +/-
Results
Negative
Test System (In vitro)
Mouse lymphoma assay
Test object
Mouse lymphoma cells L5178Y/tk +/-
Results
Positive
Test System (In vitro)
Sister chromatid exchange study
Test object
Chinese hamster cells V79
Results
Negative
Test System (In vitro)
Sister chromatid exchange study
Test object
Chinese hamster V79 cells
Results
Positive
Test System (In vitro)
Sister chromatid exchange study
Test object
Chinese hamster V79 cells
Results
Negative
Test System (In vitro)
Sister chromatid exchange study
Test object
Chinese hamster V79 cells
Results
Negative
Test System (In vitro)
Nucleus anomaly
Test object
Chinese hamster V79 cells
Results
Negative
Test System (In vitro)
DNA repair test
Test object
Rat hepatocytes
Results
Negative

WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/ALTERNATIVE and IN VITRO TESTS/ The purpose of this study was to evaluate the toxicity of diazinon oxon (DZO), a major in vivo metabolite of the organophosphate insecticide diazinon (DZ), on differentiating rat C6 glioma cells. At concentrations shown to be non-cytotoxic by both the MTT and the Kenacid blue dye binding assays (1, 5 and 10 microM), DZO caused after 24hr a reduction in the number of extensions developed from C6 cells induced to differentiate by serum withdrawal and addition of sodium butyrate. Densitometric scanning of Western blots of extracts of C6 cells demonstrated that, at all concentrations used, DZO decreased after 24hr the expression of glial fibrillary acidic protein (GFAP) compared to controls. In addition, exposure to 10 microM DZO for 24hr reduced the levels of tubulin and microtubule associated protein 1B (MAP1B). On the other hand, levels of MAP2c were not affected by DZO treatment. /Diazinon oxon/
Sidiropoulou E et al; Toxicol In Vitro. 23 (8): 1548-52 (2009)
/ALTERNATIVE and IN VITRO TESTS/ ... The effect of the organophosphate diazinon on the development of chick retinal differentiation was studied by an in vitro reaggregate approach. Reaggregated spheres from dissociated retinal cells of the E6 chick embryo were produced in rotation culture. During the whole culture period of 10 days, experimental cultures were supplemented with different concentrations of the pesticide, from 20 to 120 microM diazinon. The pesticide-treated spheres were reduced in size, and their outer surface was irregular. More importantly, inner structural distortions could be easily traced because the structure of control spheroids can be well characterized by a histotypical arrangement of laminar parts homologous to the normal retina. Acetylcholinesterase activity in diazinon-treated spheres was reduced when compared with controls. As a dramatic effect of exposure to the pesticide, inner plexiform layer (IPL)-like areas in spheroids were not distinguishable anymore. Similarly, photoreceptor rosettes and Muller radial glia were strongly decreased, whereas apoptosis was stimulated. The expression of transcripts for choline-acetyltransferase and muscarinic receptors was affected, revealing an effect of diazinon on the cholinergic system. ...
Paraoanu LE et al; Toxicol Sci. 89 (1): 314-24 (2006)
/ALTERNATIVE and IN VITRO TESTS/ Investigators/ tested the neurotoxic mechanism of two organophosphorous insecticides, chlorpyrifos and diazinon in primary cortical cultures. Exposure to the insecticides caused a concentration-dependent toxicity that could not be directly attributed to the oxon forms of the compounds which caused little toxicity but strongly inhibited AChE. Addition of 1 mM acetylcholine or carbachol actually attenuated the toxicity of chlorpyrifos and diazinon, and the muscarinic receptor antagonist, atropine, and the nicotinic receptor antagonist, mecamylamine, did not attenuate the toxicity of either insecticide. These results strongly suggest that the organophosphorous toxicity observed in this culture system is not mediated by buildup of extracellular acetylcholine resulting from inhibition of AChE. The toxicity of chlorpyrifos was attenuated by antagonists of either the /N-methyl-D-aspartate/ (NMDA) or /alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/ (AMPA)/kainate-type glutamate receptors, but the cell death was potentiated by the caspase inhibitor /benzyloxycarbonyl-Val-Ala-Asp/ (ZVAD). Diazinon toxicity was not affected by glutamate receptor antagonists, but was attenuated by ZVAD. Chlorpyrifos induced diffuse nuclear staining characteristic of necrosis, while diazinon induced chromatin condensation characteristic of apoptosis. Also, chlorpyrifos exposure increased the levels of extracellular glutamate, while diazinon did not. The results suggest two different mechanisms of neurotoxicity of the insecticides, neither one of which involved acetylcholine. Chlorpyrifos induced a glutamate-mediated excitotoxicity, while diazinon induced apoptotic neuronal death.
Rush T et al; Neuroscience 166 (3): 899-906 (2010)
/ALTERNATIVE and IN VITRO TESTS/ ... The outgrowth of axon-like processes by differentiating mouse N2a neuroblastoma cells was shown to be inhibited by exposure to 10uM diazinon. ... N2a cells were induced to differentiate for 24 hr in the presence and absence of 10 microM diazinon and 20% (v/v) conditioned medium derived from differentiating rat C6 glioma cells. Cells were then stained or lysed for morphological and biochemical analyses, respectively. The data showed that co-treatment with conditioned medium prevented the neurite inhibitory effect of diazinon. Furthermore, a significant recovery was also observed in the reduced levels of neurofilament heavy chain (NFH), heat shock protein-70 (HSP-70) and growth-associated protein-43 (GAP-43) observed as a result of diazinon treatment in the absence of conditioned medium, as seen by densitometric analysis of Western blots of cell lysates probed with monoclonal antibodies N52, BRM-22 and GAP-7B10. By contrast, no significant change was noted in the reactivity of cell lysates with antibodies against alpha- and beta-tubulin under any condition tested. After pre-incubation with a polyclonal anti-glial cell line-derived neurotrophic factor (GDNF) antibody, the conditioned medium derived from rat C6 glioma cells lost its ability to protect N2a cells against the neurite inhibitory effects of diazinon. In conclusion, these data demonstrate that C6 conditioned medium protects N2a cells from the neurite inhibitory effects of diazinon by blocking molecular events leading to axon damage and that GDNF is implicated in these effects.
Harris W et al; Neurotoxicology. 30 (6): 958-64 (2009)
/ALTERNATIVE and IN VITRO TESTS/ Preconfluent cultures of normal rat intestinal cells (IEC-6 cell line) and normal human colonic epithelial cells were treated with 0.05-50 muM doses of atrazine, diazinon, and endosulfan. After 3 days of treatment, the change in cell proliferation was quantified by cell counting or the MTT growth assay. Both intestinal and colonic epithelial cell cultures had increases in cell growth when treated with as little as 1.0 muM atrazine, diazinon, or endosulfan. The observed changes in both cultured intestinal and colonic cell growth rates were not due to the influence of the vehicle control dimethyl sulfoxide (DMSO). That is, the treatment of the cell cultures with concentrations of dimethyl sulfoxide as high as 0.5% for 3 days resulted in no change in cell growth compared with untreated control cultures. A consistent observation with all three of the compounds was that the highest doses (50 muM) had the least "proliferative potential" in stimulating either IEC-6 cell or human colonic epithelial cell growth. Within the concentration range used, none of the herbicides or pesticides caused a decrease in cell proliferation below that of the untreated control cultures. Overall, treatment of IEC-6 cell cultures with atrazine, diazinon, or endosulfan produced a biphasic growth response, whereas the same treatment in the human colonic epithelial cell cultures produced a more sustained level of growth over the same period.
Greenman SB et al; Environmental Research 75 91): 85-93 (1997)
/VETERINARY CASE REPORTS/ Two incidents involving the misuse of unlabelled or out-of-date diazinon products are described. In the first incident, 81 of a group of 210 five-month-old lambs died within 12 hours of being dipped with the contents of a partly used tin of 15-year-old sheep dip. Analysis showed that the diazinon had decomposed by hydrolysis into a range of breakdown products, including tetraethyldithiopyrophosphate (sulfotepp) and monothiono-tetraethylpyrophosphate (monothiono-TEPP), which are much more toxic to mammals than diazinon. In the second incident, four yearling bulls were affected within 48 hours of being treated with a liquid that the farmer believed to be a lice treatment but was actually old diazinon sheep dip. Three of the bulls recovered but one died four days after the treatment. Analysis of the dip confirmed the presence of diazinon but in this incident no breakdown products were detected.
Sharpe RT et al; Vet Rec. 159 (1): 16-9 (2006)
/VETERINARY CASE REPORTS/ IN SHEEP SUSCEPTIBILITY TO POISONING MAY BE INFLUENCED BY GENETIC FACTORS, SOME BREEDS BEING MORE SENSITIVE THAN OTHER.
Clarke, M. L., D. G. Harvey and D. J. Humphreys. Veterinary Toxicology. 2nd ed. London: Bailliere Tindall, 1981., p. 149
/VETERINARY CASE REPORTS/ When /diazinon/ is sprayed, young calves appear to tolerate 0.05% but are poisoned by 0.1% concentrations. Adult cattle may be sprayed repeatedly at weekly intervals with 0.1% concentrations without inducing poisoning. Diazinon appears to be tolerated by young calves at 0.44 mg/kg body wt, PO, but poisoning results at O.88 mg/kg. Adult cattle tolerate 8.8 mg/kg, PO, but are poisoned by 22 mg/kg. Sheep tolerate 17.6 mg/kg but are poisoned by 26 mg/kg.
Aiello, S.E. (ed). The Merck Veterinary Manual. 8th ed. Merck & Co., Inc., National Publishing Inc., Philadelphia, PA. 1998., p. 2067
/OTHER TOXICITY INFORMATION/ Diazinon altered the formation of several L-tryptophan metabolites associated with the L-kynurenine pathway in mice. Liver kynurenine formamidase was inhibited almost completely by diazinon (10 mg/kg). The enzyme inhibition resulted in reduced L-kynurenine biosynthesis in livers and a concomitant accumulation of N-formyl-Lkynurenine. However, in plasma, L-kynurenine level increased up to 5-fold in diazinon-treated mice. Consequently, the urinary excretion of xanthurenic acid and kynurenic acid was raised 5- to 15-fold. ...
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/OTHER TOXICITY INFORMATION/ CENTRAL EFFECTS /ORGANOPHOSPHORUS CMPD/ ... NERVOUSNESS, APPREHENSION, ATAXIA, CONVULSIONS & COMA. DEATH IS DUE TO RESP FAILURE, OR SOMETIMES CARDIAC ARREST. THERE IS LITTLE DIFFERENCE BETWEEN SYMPTOMS PRODUCED BY DIFFERENT ... CMPD, BUT ROUTE OF ABSORPTION MAY INFLUENCE ONE SYSTEM MORE THAN ANOTHER. /ORGANOPHOSPHORUS CMPD/
Booth, N.H., L.E. McDonald (eds.). Veterinary Pharmacology and Therapeutics. 5th ed. Ames, Iowa: Iowa State University Press, 1982., p. 124
/OTHER TOXICITY INFORMATION/ MUSCARINIC SIGNS OF /ORGANOPHOSPHORUS CMPD/ ... CONSIST OF HYPERSALIVATION, LACRIMATION, SWEATING & NASAL DISCHARGE. MIOSIS, DYSPNEA, VOMITING, DIARRHEA & FREQUENCY OF URINATION ... . NICOTINIC EFFECTS CONSIST OF FASCICULATION OF MUSCLES, WEAKNESS & PARALYSIS. /ORGANOPHOSPHORUS CMPD/
Booth, N.H., L.E. McDonald (eds.). Veterinary Pharmacology and Therapeutics. 5th ed. Ames, Iowa: Iowa State University Press, 1982., p. 124
/OTHER TOXICITY INFORMATION/ Diazinon is an organic phosphate that is commonly used for the control of a variety of insects around poultry houses. It should not be used inside poultry houses. Some producers have used diazinon in poultry houses for the control of fire ants. Chickens will consume the diazinon crystals, which results in lacrimation, diarrhea, dyspnea, and death. Necropsy lesions include lung edema, fatty livers, and severe enteritis. The diazinon crystals can be seen in the crop and gizzard contents.
Aiello, S.E. (ed). The Merck Veterinary Manual. 8th ed. Merck & Co., Inc., National Publishing Inc., Philadelphia, PA. 1998., p. 1943
/OTHER TOXICITY INFORMATION/ Although the common laboratory animals do not vary much in their susceptibility to single doses of diazinon, 10 mg/kg was lethal in calves but the same dosage was harmless in steers. Domestic birds were highly susceptible, with the oral LD50 being less than 10 mg/kg for turkeys and goslings.
American Conference of Governmental Industrial Hygienists, Inc. Documentation of the Threshold Limit Values and Biological Exposure Indices. 6th ed. Volumes I, II, III. Cincinnati, OH: ACGIH, 1991., p. 389
/OTHER TOXICITY INFORMATION/ Diazinon has been reported to cause acute pancreatitis & ductal hypertension in dogs, which is due to the absence of acetylcholinesterase in pancreatic sphincter, duodenal smooth muscle in dogs & a reliance upon the more readily inhibited butyrylcholinesterase.
WHO; Environ Health Criteria 198: Diazinon p.69 (1998) https://www.inchem.org/pages/ehc.html

3.2 Ecotoxicity Excerpts (Complete)

/BIRDS and MAMMALS/ Details of cases involving the inadvertent exposure of birds to eight toxic substances are recorded. The organophosphate insecticide diazinon produced respiratory symptoms.
Reece RL, Handson P; Vet Rec 111 (20): 453-5 (1982)
/BIRDS and MAMMALS/ Acute symptoms: birds- goose-stepping ataxia, wing spasms, wing drop, hunched back, dyspnea, tenesmus, diarrhea, salivation, lacrimation, ptosis of eyelid, prostration, opisthotonos-like seizures or wing-beat convulsions /oral administration/.
U. S. Department of the Interior, Fish & Wildlife Service, Bureau of Sport Fisheries & Wildlife. Handbook of Toxicity of Pesticides to Wildlife. Washington, D. C.: U. S. Government Printing Office, 1970., p. 44
/BIRDS and MAMMALS/ The exposure of red tailed hawks (Buteo jamaicensis) caught in and around 40,000 nearly continuous acres of almond orchards to organophosphorus pesticides (including diazinon) was studied. Blood and excreta samples from hawks were evaluated for the presence of organophosphorus-inhibited cholinesterase and for organophosphorus excretory metabolites, respectively. Plasma cholinesterase activities from captive control hawks average 0.790 + or - 0.162 units/mL for cholinesterase and 0.302 + or - 0.078 units/mL for AChE. Mean plasma total cholinesterase and AChE activities from the wild hawks were 0.427 + or - 0.231 and 0.130 + or - 0.071 units/mL plasma, respectively. Total cholinesterase in 6 and AChE in 6 of the 12 wild birds were more than two standard deviations below the levels for the captive hawks (under 59% and 48% of control, respectively). Reactivation of organophosphorus-inhibited total ChE was successful in four of the 14 wild caught birds. Three of the four showed reactivation of AChE activity. Blood and brain samples of five hawks found incapacitated in the area of the orchards indicated that they had been exposed to intoxicating levels of organophosphorus /insecticides/. Brain cholinesterase levels from two of the birds which died were 5.39 and 4.94 units/g brain tissue. Organophosphorus metabolite residues were recovered from both the urate and solid (fecal) portions of the samples.
Hooper MJ et al; Bull Environ Contam Toxicol 42 (5): 651-9 (1989)
/BIRDS and MAMMALS/ Bobwhite quail eggs were injected at 48 or 72 hr of incubation with various doses of the organophosphate insecticides diazinon or parathion and the embryos were examined after an additional 48 hr of incubation by both histological and cartilage-staining methods. Bobwhite embryos did not display the notochordal folding or vascular enlargement reported for organophosphate-injected chicken embryos. Cartilage staining of embryos injected with insecticide at 72 hr of incubation and recovered at day 12 of incubation revealed severe shortening and contortion of the vertebral axis, as well as tibiotarsal, rib, and sternum defects. Parathion was more potent in causing skeletal defects than diazinon. No type I defects (micromelia, parrot beak) were detected. Radiometric AChE assays of whole embryo homogenates were performed for day 6, 9, and 12 diazinon-injected and control embryos. Diazinon affected drastic reductions in AChE activity. Although the AChE and axial skeletal responses of bobwhite embryos to organophosphate injection are similar to those reported in literature for other species, some major differences in the bobwhite response were noted: namely, the absence of notochordal folding in the young bobwhite embryo and the absence of type I defects at day 12.
Meneely GA, Wyttenbach CR; J Exp Zool 252 (1): 60-70 (1989)
/BIRDS and MAMMALS/ ...In this study, homing pigeons were used as surrogate species to assess the differences in the effect of incrementally low doses (0.0, 0.25, 0.5, and 1.0 mg/kg) of carbofuran and diazinon on time of flight and determine whether there was a threshold dose of either or both xenobiotics when orally administered at these levels. The results indicate that there is a significant dose-dependent increase in flight time in pigeons dosed with carbofuran while diazinon exposed pigeons showed little effect. More profound effects were noted with carbofuran with pigeons falling off the pace of the flock and a dose for highly significant increase in flight time elucidated between 0.5 and 1.0 mg/kg.
Brasel JM et al; Toxicol Appl Pharmacol 219 (2-3): 241-6 (2007)
/AQUATIC SPECIES/ An effect of diazinon on brain acetylcholinesterase (AChE) activity of juvenile largemouth bass Micropterus salmoides was observed. The exposure concentration started from 1/10 of the 24-hr LC50 value, 90 mug/liter. The exposure duration was 24 hr. Statistically significant & dose-dependent reductions in the mean AChE activities we seen at 90, 180, 270, 360, & 450 mug/liter. The results show that juvenile brain acetylcholinesterase activities were significantly inhibited by sublethal doses of diazinon. Inhibition of brain AChE will definitely cause physiological & behavioral modifications that reduce survival ability of the animals at an early stage of growth.
PAN G et al; ENVIRONMENTAL RESEARCH 79 (2): 133-137 (1998)
/AQUATIC SPECIES/ Tiger shrimp (Penaeus japonicus) larvae at different stages were exposed to different concentrations of diazinon or its oxo-form, diazoxon. The shrimp larvae at nauplius and zoea stages were highly resistant to diazinon, with a 24 hr LC50 of 10.5 ppm. However, the toxicity of diazinon increased abruptly with the progression of the larval stages, especially at postlarva, resulting in an increase of ... /approximately/ 1,200 times that at the nauplius stage. The susceptibility of the larval acetylcholinesterase (AChE) to diazinon and diazoxon was almost unchanged from zoea to postlarva, with average I50 (50% inhibition) for diazinon and diazoxon of 1,194 and 1.27 uM respectively.
Rompas RM et al; Bull Jpn Soc Sci Fish 55 (4): 669-73 (1989)
/AQUATIC SPECIES/ Snails (Gillia altilis) were exposed to diazinon for 4 or 96 hr in laboratory aquaria. A 96 hr static renewal bioassay was also performed by changing the water in the aquaria every 24 hr to simulate a flow-through system. The value obtained for the 4 hr exposure to diazinon was 340 uM (93 ppm). The LC50 value obtained for the 96 hr exposure to diazinon was 40 uM (11 ppm). The static renewal bioassay showed an incr in toxicity for the LC50 value of the 96 hr exposure test indicating that if a flow-through system were used, the 96 hr LC50 value would be lower than reported.
Robertson JB, Mazzella C; Bull Environ Contam Toxicol 42 (3): 320-4 (1989)
/AQUATIC SPECIES/ The aim of this study was to determine the toxic effect of diazinon (organophosphate insecticide) to embryos of Xenopus laevis and Danio rerio. The 96-hr LC50 values showed higher toxicity of diazinon for X. leavis in standard solution (9.84 mg/L) compared to the pond water (12.64 mg/L). Teratogenic index for diazinon was 1.3 and 1.6, respectively. The 96-hr LC50 diazinon values demonstrated similar sensitivity of embryos D. rerio (8.21-9.34 mg/L) and X. laevis in standard test solutions.
Modra H et al; Bull Environ Contam Toxicol 86 (6): 601-4 (2011)
/AQUATIC SPECIES/ ...Carry-over toxicity was observed after exposure of the freshwater amphipod Gammarus pulex to repeated pulses of diazinon with varying intervals. Uptake, biotransformation and depuration kinetics were determined. Metabolites were identified and quantified (diazoxon, 2-isopropyl-6-methyl-4-pyrimidinol, one nonidentified metabolite). ... Organism recovery time was 28 days (95% prediction interval 25-31 days), indicating the possibility for carry-over toxicity from exposure events several weeks apart. The slow organism recovery and carry-over toxicity was caused by slow toxicodynamic recovery; toxicokinetic processes alone would have resulted in a recovery time of only 1-2 days.
Ashauer R et al; Environ Sci Technol 44 (10): 3963-71 (2010)
/AQUATIC SPECIES/ ...The study was carried out to assess the effects of the organochlorine pesticide, endosulfan and the organophosphate pesticide, diazinon on the activity of Glutathione-S-transferase (GST) of different tissues in the African common toad, Bufo regularis. Toads were exposed for 28 days to varying levels of the pesticides: 0.01, 0.02, 0.03 and 0.04 ug/L for the sublethal test. Activity of GST of toads exposed to the pesticides differentially increased significantly with increasing concentrations. The highest enhancement in GST activity was recorded in the liver followed by the brain, serum, gastrointestinal tract and lungs for both pesticide exposures. The differential increase in GST activity was tissue and pesticide specific. Liver GST increased up to 366% in endosulfan exposed toads and 393% in diazinon exposed toads in the highest concentration (0.04 ug/L). Diazinon pesticide from this study proved to be more toxic than endosulfan pesticide.
Ezemonye L, Tongo I; Chemosphere 81 (2): 214-7 (2010)
/AQUATIC SPECIES/ ...Toxicological and biochemical responses of larval fathead minnows (Pimephales promelas) exposed singly and in combinations to esfenvalerate and diazinon were determined. Exposures were 96-hr static renewal tests... After pesticide exposures, larvae were evaluated for carboxylesterase and acetylcholinesterase activity, and histopathological effects. Carboxylesterase activity was examined because of its potential influence on the toxicity of both organophosphates and pyrethroids. In vivo studies demonstrated that diazinon significantly inhibited carboxylesterase activity at nominal water concentrations as low as 50 microg/L. However, esfenvalerate did not affect carboxylesterase activity at any concentration tested. Liver glycogen depletion was the only histopathological effect observed; this effect was demonstrated with the individual pesticides and pesticide combinations (i.e., mixtures). The combinations of diazinon and esfenvalerate causing acute toxicity to fathead minnow larvae appeared to be greater than additive (i.e., synergistic) in all three tests.
Denton DL et al; Environ Toxicol Chem 22 (2): 336-41 (2003)
/AQUATIC SPECIES/ Continuous subchronic exposure experiments were conducted to assess the effects of diazinon, an organophosphate pesticide, on the survival, growth and activity of larvae of the Asian common toad Bufo melanostictus. Two larval stages, the gill stage (Gosner stages 21 and 22) and gill-atrophy stage (Gosner stages 24 and 25), were continuously exposed to 4 ug/L, 400 ug/L, and 10 mg/L of commercial-grade diazinon for 30 days. Treatments and untreated controls were maintained in triplicate with water changed and pesticide concentrations renewed every 3 days. Observations showed that subchronic exposure to 400 ug/L and 10 mg/L diazinon caused a significant dose-dependent increase in mortality compared to the control, regardless of the age at which larvae were exposed. One hundred percent mortality was observed in larvae exposed to 10 mg/L. No clear age-related sensitivity was evident in this study. The lethal concentrations at which 50% of the tadpoles (LC50) died during 30 days of continuous exposure were 6 and 7.5 mg/L for gill stage and gill-atrophy stage larvae, respectively. Diazinon impaired larval growth and activity. Tail abnormalities were apparent in larvae exposed to 400 ug/L and 10 mg/L of diazinon.
Sumanadasa DM et al; Environ Toxicol Chem 27 (11): 2320-5 (2008)
/AQUATIC SPECIES/ Young red tilapias were exposed for 96 hr to each one of 6 concentrations of the pesticide Diazinon in order to determine the pesticide's acute toxicity level. After the ascertaining the lethal concentration (LC50) at 96 hr, a level 10 times lower was selected for the bioaccumulation study of the pesticide in male and female specimens exposed for 9 days. The elimination process was carried out for 10 days beginning right after the conclusion of the accumulation process. Analytical procedures were developed and used for the studies of acute toxicity and bioaccumulation of Diazinon in red tilapia. A lethal concentration [LC50 (96 hr)] of 3.85 mg/L was found, and steady-state accumulation, at a concentration of 28.45 mg/kg, was reached at 7.72 days. In the elimination process a concentration of 0.29 mg/kg was found in tilapia tissue by the sixth day after the fish were moved to clean water, and it continued to decrease quickly toward nondetectable levels.
Palacio JL et al; Environ Toxicol 17 (4): 334-40 (2002)
/AQUATIC SPECIES/ ...Both acute toxicity and subacute effects on brain cholinesterase (ChE) of two of the most commonly used insecticides, diazinon and fenobucarb, on adult native snakehead (Channa striata) were evaluated in a static, nonrenewable system, the environmental parameters of which, such as dissolved oxygen, water temperature, and pH, fluctuated similarly to field conditions. Four levels of insecticides, from 0.008 to 0.52 mg/L (for diazinon) and from 0.11 to 9.35 mg/L (for fenobucarb), were tested to assess the effects on the brain ChE activity of the snakehead up to 30 and 10 days for diazinon and fenobucarb, respectively. Diazinon was highly toxic to this fish species, with a 96-hr median lethal concentration (LC50) of only 0.79 mg/L, and it also caused long-term ChE inhibition, with activity still significantly inhibited by 30% after 30 days for the three highest concentrations. ...
VanCong N et al; Environ Toxicol Chem 25 (5): 1418-25 (2006)
/AQUATIC SPECIES/ ... Static-renewal (96 hr) exposures to /Chinook salmon/ eyed eggs and alevins resulted in both toxicity and significant changes in metabolism assessed in whole-embryo extracts by (1)H nuclear magnetic resonance (NMR) spectroscopy based metabolomics and HPLC with UV detection (HPLC-UV). The 96-hr LC(50) values of eyed eggs and alevins exposed to dinoseb were 335 and 70.6 ppb, respectively, and the corresponding values for diazinon were 545 and 29.5 ppm for eyed eggs and alevins, respectively. ...Phosphocreatine, as measured by HPLC-UV, decreased significantly in eyed eggs due to 250 ppb dinoseb, 10 and 100 ppb esfenvalerate, and 100 ppm diazinon (p < 0.05). Principal components analyses of (1)H NMR metabolite fingerprints of eyed egg and alevin extracts revealed both dose-dependent and mechanism of action-specific metabolic effects induced by the pesticides. ...Significant metabolic perturbations to the early life stages of Chinook salmon by currently used pesticides /were identified/.
Viant MR et al; Aquat Toxicol 77 (4): 359-71 (2006)
/AQUATIC SPECIES/ Effects of diazinon, at different concentrations and exposure times, were investigated in freshwater fish, Cyprinus carpio, to elucidate the possible mode of action on lipid peroxidation together with the inhibitory effect of diazinon on acetylcholinesterase activity and changes in tissue protein levels. Cholinesterase inhibition is considered to be a specific biomarker of exposure to organophosphorus pesticides. Fish were exposed to 0.0036 ug/L, 0.018 ug/L, and 0.036 ug/L (sublethal) concentrations of diazinon for 5, 15, and 30 days, and biochemical measurements were carried out spectrophotometrically. Brain was chosen as an indicator tissue because it is a target system for the organophosphorus action. More than 20% decline in acetylcholinesterase activity relative to mean activity of the controls was observed in the diazinon-exposed groups. Protein content decreased significantly after 15 days of exposure to 0.018 ug/L and 0.036 ug/L diazinon and after 30 days of exposure to 0.036 ug/L. Malondialdehyde level declined markedly compared with the control levels. This study showed that prolonged exposures of C. carpio to diazinon had significant effects on brain acetylcholinesterase activity and that environmentally relevant concentrations of diazinon can significantly inhibit brain acetylcholinesterase activity. Altered protein content was probably due to the high energy demand under pesticide stress or inhibition of de novo enzyme synthesis. The decreased malondialdehyde content may reflect the possibility of better protection against oxidative stress.
Ozcan O et al; Drug Chem Toxicol 29 (1): 57-67 (2006)
/AQUATIC SPECIES/ Diazinon, an organophosphate pesticide, becomes biotransformed to a more potent oxon metabolite that inhibits acetylcholinesterase (AChE). Early life stages (els) of medaka, Oryzias latipes, were used to determine how development of this teleost affects sensitivity to diazinon. With developmental progression, from day of fertilization to 7-day-old larvae, ...96-hr LC50 and AChE IC50 values decreased, indicating greater host sensitivity to diazinon upon continued development. ...Changes in AChE activity, its inhibition by the active metabolite diazoxon, and uptake and bioactivation of the compound /were examined/. AChE activity remained low during much of development but increased rapidly just prior to hatch. In addition, in vitro incubation of tissue homogenates from embryos or larvae showed no differences in the sensitivity of AChE to diazoxon. Uptake studies with 14C-diazinon revealed greater body burdens of 14C as medaka developed. In addition, AChE IC50 values determined by in vivo exposure to diazoxon were greater in larvae than in embryos. Because diazinon is bioactivated by the P450 enzyme system, two P450 inhibitors were used in vivo to explore the role of metabolism in sensitivity. When exposure to diazinon occurred in the presence of increasing amounts of piperonyl butoxide (PBO), AChE inhibition decreased in a dose-response fashion and 2.0 x 10(-5) M PBO alleviated any difference in inhibition between larvae and embryos. However, PBO did not alter total 14C uptake when exposed simultaneously with 14C-diazinon, nor did it affect AChE inhibition using diazoxon. Controls ruled out differential effects of PBO on uptake and inhibition. In addition, a second general P450 inhibitor, 1-aminobenzotriazole, also decreased AChE inhibition. Finally, using exogenous acetylcholinesterase as a trap for the oxon metabolite, larval microsomes displayed greater bioactivation of diazinon than did a microsomal preparation from embryos.
Hamm JT et al; Toxicol Sci 61 (2): 304-13 (2001)
/AQUATIC SPECIES/ ... Fathead minnow embryos and the resulting larvae /were exposed/ to diazinon for 32 days in an early-life stage test. At test termination, wet weight and survival of test fish exposed to only the highest exposure concentration of 285 ug/L were significantly different from that of the control fish. Total length was significantly affected at concentrations >160 ug/L and dry weight was significantly reduced at 37.8 ug/L, but not at 16.5 ug/L.
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.7 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
/AQUATIC SPECIES/ Fathead minnow embryos (<24-hr old) and the resulting larvae were exposed to diazinon for a total of 32 days. Results of the early-life stage test were reduced survival at diazinon concentrations >290 ug/L, and reduced weight (10.1% reduction) at 90 ug/L, but no weight difference from the control fish at 50 ug/L.
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.7 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
/AQUATIC SPECIES/ ... Brook trout adults /were exposed/ to diazinon for six to eight months and then ... their progeny /were exposed/ for an additional 122 days and ... effects /were observed/. After 173 days of exposure, survival was reduced at 9.6 ug/L and deformities were seen at 4.8 ug/L. However, when these fish spawned there were no differences in the number of eggs produced per female or the viability of these eggs. Continued exposure of the progeny showed measurable effects at 30 days, but at 122 days post-hatch, all exposure concentrations had significantly shorter total lengths and lighter weights.
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.6 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
/AQUATIC SPECIES/ Flagfish were exposed to diazinon through one and one-half generations. The study began with one-day-old larvae and continued through spawning, which occurred at about 60 days, then continued with the fish progeny for 35 days post-hatch. An effect was seen with the parents at 61 days of exposure. The average wet weight of the males was significantly reduced from that of the control fish at diazinon concentrations >88 ug/L. Only two male fish were exposed per treatment and there was a 23.3% reduction in wet weight in the 88 ug/L exposure. However, weights of the four female fish from each treatment were not significantly reduced at any exposure concentration even though fish in the highest exposure concentration were reduced in average weight by 21.4%. Effects on the progeny were then observed and the only effect seen at hatching was a reduction in the incubation time at all exposure concentrations. At 35 days post-hatch, or a total exposure time of 96 days, significant reductions in average wet weight were measured at all exposure concentrations.
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.7 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
/AQUATIC SPECIES/ Zebrafish eggs (approximately 2-3 hr after spawning) through juveniles were exposed to diazinon concentration of 8, 40 and 200 ug/L for 42 days under flow-through measured conditions. Survival and growth of the three treatment groups were not statistically different (p<0.05) from the controls.
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.8 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
/AQUATIC SPECIES/ The chronic toxicity of diazinon for saltwater organisms has been determined in a life cycle test with the mysid, A. bahia, and a partial lifecycle test with the sheepshead minnow. The mysid test was of 22 days duration... . There was no statistical difference in survival observed between the highest concentration tested (4.4 ug/L) and the controls (although there was only 28% survival at the highest concentration). Mysid reproduction was not significantly reduced in diazinon concentrations <2.1 ug/L, and only the 4.4 ug/L exposure concentration exhibited significantly reduced reproduction when compared to controls. Based on these observations, the chronic limits were 2.1 and 4.4 ug/L... . Sheepshead minnow reproduction was significantly reduced in all diazinon exposure concentrations observed during a partial life-cycle test. The number of eggs spawned per female in the 0.47, 0.98, 1.8, 3.5 and 6.5 ug diazinon/L average measured concentrations were 69, 50, 50, 55 and 45% of control fish, respectively. Acetylcholinesterase activity in fish exposed to 0.47 ug/L was consistently less than control fish levels, and levels averaged 71% inhibition in the 6.5 ug/L exposure. Neither survival nor growth were affected in <6.5 ug/L exposures to diazinon.
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.8 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
/AQUATIC SPECIES/ A life-cycle test was conducted with C. dubia during a seven-day exposure. Diluted mineral reconstituted water was used to culture and expose the organisms. All organisms survived in the control and the three lowest exposures (0.063, 0.109, and 0.220 ug/L), but no organisms survived at concentrations >0.520 ug/L.
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.6 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
/AQUATIC SPECIES/ Relations between neurotoxicants and changes in physiological parameters and behavior were investigated in larval rainbow trout (RBT; Oncorhynchus mykiss) exposed to sublethal concentrations of two organophosphate pesticides (OPs). Fish were exposed to diazinon and malathion in static-renewal experiments. After exposures for 24, 96, or 96 hr, followed by 48 hr of recovery, individual RBT were videotaped to assess locomotory behaviors. Brain tissue from the same fish was assayed for the physiological endpoints, cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number (/maximum specific binding/ Bmax), and MChR affinity (KD). Cholinesterase activity decreased significantly with increasing concentrations of both diazinon and malathion and differed significantly among exposure durations, with 24- and 96-hr means less than 48-hr recovery means. Decreases in Bmax with OP concentration were not significant for either chemical, and KD was unaffected. Changes in swimming speed and distance were significantly correlated with changes in ChE activity for both chemicals; rate of turning was significantly correlated with ChE activity in malathion exposures. These results suggest that correlations between physiological and behavioral changes previously seen in mammals also occur in fish.
Beauvais SL et al; Environ Toxicol Chem 19 (7): 1875-80 (2000)
/OTHER TERRESTRIAL SPECIES/ ...The bioavailability of composted delta-2-14C-diazinon and its degradation products to earthworms (Eisenia foetida Savigny) in 30 and 60 day compost amended soil /was studied/. ...Soil amended with 30-day composted diazinon was toxic to earthworms whereas, no mortality was observed in those earthworms exposed to the 60-day composted diazinon. However, earthworms exposed to 30-day and 60-day composted diazinon were found to have similar levels of radioactivity in their tissues. The majority of the radioactivity in earthworms exposed 60-day composted diazinon was either unextractably bound within the earthworm tissue or was not acetone soluble. Most of the radioactivity that could be extracted with acetone was not separated by the two HPTLC methods we used. This study demonstrates that composting high concentrations of diazinon can greatly reduce toxicity and the amount of diazinon that is bioavailable to a representative soil macroinvertebrate (E. foetida).
Leland JE et al; J Environ Sci Health B 38 (6): 697-712 (2003)
/OTHER TERRESTRIAL SPECIES/ Colonies of the honey bee, Apis mellifera, showed variation in tolerance to the insecticides diazinon, propoxur, aldrin & carbaryl. Tolerance to diazinon and propoxur was positively related to midgut mixed-function oxidase and glutathione transferase enzyme activities, but tolerance to aldrin was inversely related to these enzymes. Differences in tolerance to carbaryl were evident among colonies but were not related to enzyme activity levels. Linear regression models derived from these data may be used to predict colony tolerance from enzyme activity and may enable the selection of tolerant strains of bees that could maintain efficient pollination in areas of extensive insecticide use.
Smirle MJ: J Econ Entomol 83 (3): 715-20 (1990)
/FIELD STUDIES/ ...Gray-tailed voles (Microtus canicaudus) and northern bobwhite quail (Colinus virginianus) /were used/ as experimental model species to field test whether small mammals and birds respond differently to equivalent concentrations of a pesticide applied in granular and flowable formulations. In mid-May 1998, ...voles /were placed/ into 15, 0.2-ha enclosures planted with a mixture of pasture grasses. In mid-July, we placed quail into the same enclosures with the voles. In late July, we applied the organophosphorus insecticide diazinon in five treatments; a control (all habitats sprayed with water), liquid formulation of diazinon at 0.55 kg/ha, liquid formulation of diazinon at 1.11 kg/ha, broadcast of granular diazinon at 1.11 kg/ha, and broadcast of granular diazinon at 2.22 kg/ha. The diazinon treatment in liquid and granular formulations did not depress population size or growth rate, or survival rate of voles. We found a significant difference in the survival rate of the quail between the controls and treatments; granular diazinon caused a measurable decline of quail survival, whereas the liquid application at an equivalent rate did not significantly affect quail survival. Analysis of our results suggests that ground-feeding birds are more susceptible to granular insecticides than flowable applications, but voles were not susceptible to either formulation at the rate we used.
Wang G et al; Environ Toxicol Chem 20 (2): 406-11 (2001)
/FIELD STUDIES/...Using 12 0.1-ha terrestrial mesocosms, ...the effects of low-level diazinon exposure on the small mammal communities inhabiting semi-enclosed grassland ecosystems /was examined/. Our primary objective was to test the hypothesis that diazinon, applied at two different recommended label application rates, would not cause any observable adverse ecological or reproductive effects on small mammal populations and communities. Experimental small mammal communities consisting of Sigmodon hispidus, Microtus ochrogaster, Reithrodontomys fulvescens, and Mus musculus were stocked at natural densities and sex ratios inside empty mesocosms. Diazinon 4E was applied at two different maximum recommended label application rates, 0.56 kg a.i./ha (1x) and 4.5 kg a.i./ha (8x), and controls remained unsprayed, with four enclosures (replicates) per treatment. Two 30-day trials were run during peak rodent breeding seasons and enclosures were sampled on days 2, 16, and 30 of each trial. Recovery of small mammals was not significantly different among treatments, although fewer animals were recovered from the diazinon-exposed enclosures in both trials. Analysis of trapping data suggested that the normally strong competitive relationship between Sigmodon and Microtus may be altered by the pesticide, favoring Microtus in the diazinon-exposed enclosures. Incidence of reproductive condition was found to be reduced 20 to 80% and 33 to 100% in diazinon-exposed males and females, respectively. Reproductive productivity, including percentage of pregnant females and of females giving birth, was significantly reduced in diazinon-exposed animals. Percentage of pregnant females ranged from 13.6 to 43.5% in diazinon-exposed animals compared to 40 to 80% for control animals, and percentage of females giving birth ranged from 0 to 17% in diazinon-exposed animals compared to 22 to 50% for control animals. Generally, the effects found in this study suggest that diazinon was relatively persistent in the sprayed enclosures and that oral routes of exposure (consumption of dead and dying arthropods, grooming) may have been important. Ecological relationships and reproduction in both herbivorous and omnivorous mammals were negatively impacted by diazinon exposure. Overall, ecological relationships in the enclosed prairie grassland ecosystem were disrupted by diazinon, probably through a combination of sublethal effects, particularly reproductive effects, impacting individuals and their populations. This suggests that negative impacts on populations and community structure and function may persist longer than diazinon persists in the environment.
Sheffield SR, Lochmiller RL; Environ Toxicol Chem 20 (2): 284-96 (2001)
/FIELD STUDIES/ The effects of diazinon on macroinvertebrates were assessed in 3 outdoor experimental channels from mid-May to mid-Sept, 1980. One channel served as a control and 2 channels as low and high treatments. Three dosing regimes were employed. The low and high treatment channels were continuously dosed for 12 wk to nominal concentrrations of 0.3 and 3 ug/L, then increased to 6 and 12 ug/L for 4 wk, then the high treatment was increased to 30 ug/L with the low treatment channel returned to ambient. Diazinon concentration did not reach the intended levels during the latter 2 dosing regimes. No consistent interchannel differences were observed in total macroinvertebrate abundance or in species diversity indices. Effects were noted at the lowest concentration for amphipods and insects. As diazinon concentrations were increased, interchannel community structure changes became more pronounced. Elevated drift, especially amphipods and snails, occurred in the treated channels 4 wk after dosing began and following the increases in concentration. Total number and species of insects emerging from the 3 channels were not greatly different but lower number of mayflies and damselflies emerged from the treated channels. Tolerance of macroinvertebrates to diazinon were as follows: flatworms, physid snails, isopods, and chironomides most tolerant; leeches and the amphipod crangonyx less tolerant; the amphipod hyalella, caddisflies and damselflies sensitive.
Arthur JW et al; Aquat Toxicol 4 (4): 283-301 (1983)

3.3 National Toxicology Program Studies (Complete)

A bioassay of diazinon for possible carcinogenicity was conducted by admin the test chemical in feed to F344 rats and B6C3F1 mice. Groups of 50 rats and 50 mice of each sex were administered diazinon at one of two doses, either 400 or 800 ppm for the rats and either 100 or 200 ppm for the mice, for 103 wk and were then observed for an additional 1 or 2 wk. Matched controls consisted of 25 untreated rats and 25 untreated mice of each sex. All surviving animals were killed at the end of 104 or 105 wk. ... Under the conditions of this bioassay, diazinon was not carcinogenic for F344 rats or B6C3F1 mice of either sex. Levels of Evidence of Carcinogenicity: Male Rats: Negative; Female Rats: Negative; Male Mice: Negative; Female Mice: Negative.
Bioassay Diazinon for Possible Carcinogenicity (1979) Technical Rpt Series No. 137 DHEW Pub No. (NIH) 79-1392, U.S. Department of Health Education and Welfare, National Cancer Institute, Bethesda, MD 20014

3.4 Non-Human Toxicity Values (Complete)

LD50 Rat male oral 1340 mg/kg
USEPA; Diazinon: Diazinon Aggregate Human Health Risk Assesment. Document ID: EPA-HQ-OPP-2008-0351-0005 p. 24 (April 12, 2000). Available from, as of September 2, 2011: https://www.regulations.gov/#!home
LD50 Rat female oral 1160 mg/kg
USEPA; Diazinon: Diazinon Aggregate Human Health Risk Assesment. Document ID: EPA-HQ-OPP-2008-0351-0005 p. 24 (April 12, 2000). Available from, as of September 2, 2011: https://www.regulations.gov/#!home
LC50 Rat inhalation >5540 mg/cu m 4 hr
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LC50 Rat inhalation >2330 mg/cu m 4 hr
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Rabbit oral 130 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Guinea pig oral 320 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Mouse i.p. 65 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Mouse oral 187 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Mouse oral 96 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Mouse male oral 82 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Rat dermal >2150 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Rat female dermal 455 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Rat male dermal 900 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 459
LD50 Rat oral 422 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Rat oral 300 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Rat male oral 435 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Rat male oral 235 mg/kg
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
LD50 Hen oral 12.5 mg/kg
California Environmental Protection Agency/Department of Pesticide Regulation; Toxicology Data Review Summary for Diazinon (333-41-5) p.18 (April 15, 1999). Available from, as of August 31, 2011: https://www.cdpr.ca.gov/docs/risk/toxsums/toxsumlist.htm
LD50 Rabbit dermal >2020 mg/kg bw
European Chemicals Bureau; IUCLID Dataset for Diazinon (333-41-5), p.23 (2000 CD-ROM edition). Available from, as of August 30, 2011: https://esis.jrc.ec.europa.eu/
LC50 Rat inhalation >2.33 mg/L 4 hr
European Chemicals Bureau; IUCLID Dataset for Diazinon (333-41-5), p.23 (2000 CD-ROM edition). Available from, as of August 30, 2011: https://esis.jrc.ec.europa.eu/
LC50 Rat inhalation >5.44 mg/L 4 hr
European Chemicals Bureau; IUCLID Dataset for Diazinon (333-41-5), p.22 (2000 CD-ROM edition). Available from, as of August 30, 2011: https://esis.jrc.ec.europa.eu/
LD50 Rat oral 1250 mg/kg bw
European Chemicals Bureau; IUCLID Dataset for Diazinon (333-41-5), p.22 (2000 CD-ROM edition). Available from, as of August 30, 2011: https://esis.jrc.ec.europa.eu/
LD50 Rat oral 1012 mg/kg bw
European Chemicals Bureau; IUCLID Dataset for Diazinon (333-41-5), p.22 (2000 CD-ROM edition). Available from, as of August 30, 2011: https://esis.jrc.ec.europa.eu/
LD50 Rat oral 696 mg/kg bw
European Chemicals Bureau; IUCLID Dataset for Diazinon (333-41-5), p.21 (2000 CD-ROM edition). Available from, as of August 30, 2011: https://esis.jrc.ec.europa.eu/
LD50 Rat male oral 250 mg/kg
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509
LD50 Rat female oral 285 mg/kg
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509
LD50 Rat male oral 108 mg/kg
American Conference of Governmental Industrial Hygienists. Documentation of the Threshold Limit Values and Biological Exposure Indices. 5th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, 1986., p. 172
LD50 Rat female oral 76 mg/kg
American Conference of Governmental Industrial Hygienists. Documentation of the Threshold Limit Values and Biological Exposure Indices. 5th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, 1986., p. 172
LD50 Guinea pig oral 240-320 mg/kg
American Conference of Governmental Industrial Hygienists. Documentation of the Threshold Limit Values and Biological Exposure Indices. 5th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, 1986., p. 172
LD50 Rabbit acute 130 mg/kg
American Conference of Governmental Industrial Hygienists. Documentation of the Threshold Limit Values and Biological Exposure Indices. 5th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, 1986., p. 172
LD50 Rat oral 300-400 mg/kg (technical grade)
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 459
LD50 Rat female dermal 445 mg/kg
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 459
LD50 Rat acute oral 66 mg/kg
Montgomery, J.H.; Agrochemicals Desk Reference 2nd ed. Lewis Publishers, Boca Raton, FL 1997, p. 146
LD50 Rat acute oral 240-480 mg/kg
Montgomery, J.H.; Agrochemicals Desk Reference 2nd ed. Lewis Publishers, Boca Raton, FL 1997, p. 146
LD50 Guinea pig acute oral 250-355 mg/kg
Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994., p. 297
LD50 Mouse acute oral 80-135 mg/kg
Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994., p. 297
LD50 Rat acute percutaneous > mg/kg 2150; rabbit acute percutaneous 540-650 mg/kg
Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994., p. 297
LD50 Rat oral 66 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Rat dermal 180 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Rat ip 65 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Mouse oral 17 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Mouse dermal 2750 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Mouse ip 33 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Mouse sc 58 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Mouse iv 180 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Rabbit oral 143 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Rabbit dermal 180 mg/kg
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 1127
LD50 Turkey oral 6.8 mg/kg /from table/
WHO; Environ Health Criteria 198: Diazinon p.45 (1998)
LD50 Chicken oral 40.8 mg/kg /from table/
WHO; Environ Health Criteria 198: Diazinon p.45 (1998)
LD50 Goose oral 14.7 mg/kg /from table/
WHO; Environ Health Criteria 198: Diazinon p.45 (1998)
LD50 Gosling oral 2.8 mg/kg /from table/
WHO; Environ Health Criteria 198: Diazinon p.45 (1998)

3.5 Ecotoxicity Values (Complete)

LD50; Species: Anas platyrhynchos (Mallard duck) male, age 3-4 months oral 3.54 mg/kg (95% confidence limits: 2.37-5.27 mg/kg)
U. S. Department of the Interior, Fish & Wildlife Service, Bureau of Sport Fisheries & Wildlife. Handbook of Toxicity of Pesticides to Wildlife. Washington, D. C.: U. S. Government Printing Office, 1970., p. 44
LD50; Species: Anas platyrhynchos (Mallard ducklings) acute oral 3.5 mg/kg
Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994., p. 297
LC50; Species: Coturnix (Quail) oral 167 ppm (99% active ingredient)
Hill, E.F. and Camardese, M.B. Lethal Dietary Toxicities of Environmental Contaminants and Pesticides to Coturnix. Fish and Wildlife Technical Report 2. Washington, DC: United States Department of Interior Fish and Wildlife Service, 1986., p. 54
LC50; Species: Coturnix (Quail) oral 101 ppm (48% active ingredient)
Hill, E.F. and Camardese, M.B. Lethal Dietary Toxicities of Environmental Contaminants and Pesticides to Coturnix. Fish and Wildlife Technical Report 2. Washington, DC: United States Department of Interior Fish and Wildlife Service, 1986., p. 54
LD50; Species: (Pheasant) male, age 3-4 months oral 4.33 mg/kg (95% confidence limits: 3.02-6.22 mg/kg)
U. S. Department of the Interior, Fish & Wildlife Service, Bureau of Sport Fisheries & Wildlife. Handbook of Toxicity of Pesticides to Wildlife. Washington, D. C.: U. S. Government Printing Office, 1970., p. 44
EC50; Species: Pseudokirchneriella subcapitata (Green Algae); Conditions: freshwater, static; Concentration: 3700 ug/L for 7 days; Effect: population abundance /formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
EC50; Species: Pseudokirchneriella subcapitata (Green Algae) 1.42x10+6 cells/mL; Conditions: freshwater, static, 24 °C; Concentration: 6400 ug/L for 7 days; Effect: population change /87.7% technical/
Hughes J; USEPA-OPP Registration Standard; The Toxicity of Diazinon Technical to Selenastrum capricornutum (1988) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
EC50; Species: Selenastrum capricornutum (Green algae); Conditions: freshwater, static; Concentration: 6400 ug/L for 7 days; Effect: reduced cell numbers
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.9 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
LD50; Species: (Bullfrog) female oral >2000 mg/kg
U. S. Department of the Interior, Fish & Wildlife Service, Bureau of Sport Fisheries & Wildlife. Handbook of Toxicity of Pesticides to Wildlife. Washington, D. C.: U. S. Government Printing Office, 1970., p. 44
LC50; Species: Gillia altilis (snail); Conditions: static renewal bioassay; Concentration: 40 uM (11 ppm) for 96 hr
Robertson JB, Mazzella C; Bull Environ Contam Toxicol 42 (3): 320-4 (1989)
LC50; Species: Lumbriculus variegatus (oligochaete worm); Conditions: freshwater, static, hardness 46-48 mg/L CaCO3; Concentration: 9980 ug/L for 96 hr /Technical, 85% purity/
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.28 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
LC50; Species: Lumbriculus variegatus (oligochaete worm); Conditions: freshwater, static, hardness 42-47 mg/L CaCO3; Concentration: 6160 ug/L for 96 hr /Technical, 95% purity/
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.28 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
LC50; Species: Acartia tonsa (calanoid copepod); Concentration: 2.57 ug/L for 96 hr /Conditions of bioassay not specified/
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 458
LC50; Species: Pteronarcys californica (stonefly); Concentration: 25 ug/L for 96 hr /Conditions of bioassay not specified/
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 458
EC50; Species: Daphnia magna (Water Flea) age <24 hr neonate; Conditions: freshwater, static, 21 °C; Concentration: 6.1 ug/L for 48 hr (95% confidence interval: 4.8-7.4 ug/L); Effect: intoxication, immobilization /100% purity formualtion/
Jemec A et al; Comp Biochem Physiol 144C (4): 303-9 (2007) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
EC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, static; Concentration: 0.47 ug/L for 24 hr; Effect: behavior, filtration rate /92% purity/
Fernandez-Casalderrey A et al; Ecotoxicol Environ Saf 27 (1): 82-89 (1994) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
EC50; Species: Daphnia magna (Water Flea) 1st instar larvae; Conditions: freshwater, static; Concentration: 0.96 ug/L for 48 hr (95% confidence interval: 0.83-1.1 ug/L); Effect: intoxication, immobilization
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
EC50; Species: Daphnia magna (Water Flea) 48 hr; Conditions: freshwater, static; Concentration: 0.5 ug/L for 48 hr (95% confidence interval: 0.4-0.59 ug/L); Effect: intoxication, immobilization /23% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
EC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, static; Concentration: 1.1 ug/L for 48 hr (95% confidence interval: 1.0-1.3 ug/L); Effect: intoxication, immobilization /48% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Daphnia magna (Water Flea) age <48 hr; Conditions: freshwater, static, 20 °C, hardness 60-80 mg/L CaCO3, alkalinity 60-80 mg/L CaCO3; Concentration: 2.39 ug/L for 48 hr (95% confidence interval: 1.63-3.42 ug/L) /5% purity granule formulation (Ortho fire ant repellant)/
Burkepile DE et al; Bull Environ Contam Toxicol 64 (1): 114-21 (2000) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Daphnia magna (Water Flea) age < or =48 hr; Conditions: freshwater, static, 25 °C; Concentration: 0.80 ug/L for 48 hr (95% confidence interval: 0.65-1.00 ug/L) /95-99% purity formulation/
Ankley GT et al; Ecotoxicol Environ Saf 21 (3): 266-74 (1991) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Americamysis bahia (Opossum Shrimp) age 24 hr; Conditions: saltwater, flow through; Concentration: 4.2 ug/L for 96 hr (95% confidence interval: 3.7-4.8 ug/L) /87.7% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Americamysis bahia (Opossum Shrimp) age < or =24 hr juvenile; Conditions: saltwater, static, 25 °C, pH 4.3-5.9, salinity 7.8-8.1 ppt, conductivity 25 umhos/cm; Concentration: 8.5 ug/L for 96 hr (95% confidence interval: 8.2-8.9 ug/L) /formulation/
Cripe GM; Environ Toxicol Chem 13 (11): 1867-72 (1994) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Ceriodaphnia dubia (Water Flea) age <24 hr neonate; Conditions: freshwater, static, 25 °C, pH 8.35-8.36, hardness 175 mg/L CaCO3, alkalinity 136 mg/L CaCO3; Concentration: 0.21 ug/L for 48 hr /99.8% purity/
Banks KE et al; Ecotoxicol Environ Saf 60 (1): 28-36 (2005) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Ceriodaphnia dubia (Water Flea) age <24 hr neonate; Conditions: freshwater, static, 25 °C, pH 8.35-8.36, hardness 175 mg/L CaCO3, alkalinity 136 mg/L CaCO3; Concentration: 0.45 ug/L for 48 hr /99.8% purity formulation/
Banks KE et al; Environ Toxicol Chem 22 (7): 1562-7 (2003) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Ceriodaphnia dubia (Water Flea) age 6-18 hr; Conditions: freshwater, renewal, 25 °C; Concentration: 0.4 ug/L for 96 hr /100% purity/
Werner I et al; Bull Environ Contam Toxicol 68 (1): 29-36 (2002) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Gammarus fasciatus (Amphipod) mature; Conditions: freshwater, static, hardness 44 mg/L CaCO3; Concentration: 0.20 ug/L for 96 hr /Technical, 89% purity/
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.28 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
LC50; Species: Gammarus lacustris (Scud) age 2 months; Conditions: freshwater, static, 21.1 °C, pH 7.1, alkalinity 30.0 mg/L CaCO3; Concentration: 500 ug/L for 48 hr (95% confidence interval: 400-620 ug/L) /formulation/
Sanders HO; USDI/FWS, Bur Sports Fish Wildl Tech Pap No.25: 18 (1969) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Gammarus lacustris (scud); Concentration: 200 ug/L for 96 hr /Conditions of bioassay not specified/
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 458
LC50; Species: Hyalella azteca (Amphipod) age 7-14 days; Conditions: freshwater, static, hardness 42-47 mg/L CaCO3; Concentration: 6.51 ug/L for 96 hr /Technical, 95% purity/
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.28 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
LC50; Species: Daphnia pulex (Water flea); Concentration: 0.90 ug/L for 96 hr /Conditions of bioassay not specified/
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 458
LC50; Species: Simocephalus serrulatus (water flea); Concentration: 1.4 ug/L for 48 hr /Conditions of bioassay not specified/
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 458
LC50; Species: Dugesia tigrina (Planaria); Conditions: freshwater, static, hardness 46.5-47.5 mg/L CaCO3; Concentration: 11,640 ug/L for 96 hr /Technical, 85% purity/
USEPA/Office of Water; Draft Ambient Aquatic Life Water Quality Criteria Diazinon. p.27 Identification Number: EPA-822-R-03-017 (August 2000). Available from, as of November 5, 2011: https://www.regulations.gov/#!home
LC50; Species: Cyprinus carpio (Common Carp) age 1-2 yr juvenile, weight 9.0 g, length 67.2 cm; Conditions: freshwater, renewal, 19-21 °C, pH 7.82, hardness 14 mg/L CaCO3, alkalinity 1.05 mg/L CaCO3; Concentration: 26700 ug/L for 96 hr /100% purity formulation/
Svoboda M et al; Acta Vet Brno 70: 457-65 (2001) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) eyed egg or eyed embryo stage; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 7200 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 1-3 days yolk sac fry/sac fry, length 0.5-0.7 cm; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 6100 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 5-6 days fry, floating, length 0.7-0.8 cm; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 2500 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 9-10 days, weight 0.007-0.020 g, length 1.0-1.4 cm; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 2700 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 17-19 days, weight 0.020-0.068 g, length 1.4-1.7 cm; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 2800 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 25-33 days, weight 0.19-0.28 g, length 2.4-2.7 cm; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 2300 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 50-60 days, weight 0.62-1.37 g, length 3.4-4.5 cm; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 1900 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 70-80 days, weight 1.46-3.60 g, length 4.6-5.8 cm; Conditions: freshwater, static, 25 °C, pH 6.9-7.2; Concentration: 2400 ug/L for 24 hr
Hashimoto Y et al; J Pestic Sci 7 (4): 457-61 (1982) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) length 7-9 cm; Conditions: freshwater, static, 28-32 °C; Concentration: 3180 ug/L for 24 hr /20% purity emulsifiable concentrate formulation/
Toor HS, Kaur K; Indian J Exp Biol 12 (4): 334-6 (1974) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) length 7-9 cm; Conditions: freshwater, static, 28-32 °C; Concentration: 3140 ug/L for 48 hr /20% purity emulsifiable concentrate formulation/
Toor HS, Kaur K; Indian J Exp Biol 12 (4): 334-6 (1974) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) length 7-9 cm; Conditions: freshwater, static, 28-32 °C; Concentration: 3110 ug/L for 72 hr /20% purity emulsifiable concentrate formulation/
Toor HS, Kaur K; Indian J Exp Biol 12 (4): 334-6 (1974) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio (Common Carp) age 1 yr, length 6-10 cm; Conditions: freshwater, static, 8 °C; Concentration: 0.072 ug/L for 96 hr /formulation/
Dembele K et al; Ecotoxicol Environ Saf 45 (1): 49-54 (2000) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio ssp. communis (Carp) age ~30 min egg; Conditions: freshwater, renewal, 24 °C, pH 7.1, hardness 125.1 mg/L CaCO3; Concentration: 999 ug/L for 48 hr /63% purity formulation/
Aydin R, Koprucu K; Pestic Biochem Physiol 82 (3): 220-5 (2005) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio ssp. communis (Carp) larvae; Conditions: freshwater, renewal, 24 °C, pH 7.1, hardness 125.1 mg/L CaCO3; Concentration: 1530 ug/L for 96 hr /63% purity formulation/
Aydin R, Koprucu K; Pestic Biochem Physiol 82 (3): 220-5 (2005) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Cyprinus carpio ssp. communis (Carp) eggs; Conditions: freshwater, static, 26 °C; Concentration: 8 ug/L until hatch /100% purity formulation/
Kaur K, Toor HS; Indian J Exp Biol 15: 193-6 (1977) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Danio rerio (Zebra Danio); Conditions: freshwater, static; Concentration: 2300 ug/L for 24 hr (95% confidence interval: 2250-2350 ug/L) /formulation/
Ansari BA et al; Acta Hydrochim Hydrobiol 15 (3): 301-6 (1987) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Danio rerio (Zebra Danio); Conditions: freshwater, static; Concentration: 2240 ug/L for 48 hr (95% confidence interval: 2180-2300 ug/L) /formulation/
Ansari BA et al; Acta Hydrochim Hydrobiol 15 (3): 301-6 (1987) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Danio rerio (Zebra Danio); Conditions: freshwater, static; Concentration: 2190 ug/L for 72 hr (95% confidence interval: 2120-2260 ug/L) /formulation/
Ansari BA et al; Acta Hydrochim Hydrobiol 15 (3): 301-6 (1987) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Danio rerio (Zebra Danio); Conditions: freshwater, static; Concentration: 2120 ug/L for 96 hr (95% confidence interval: 2080-2160 ug/L) /formulation/
Ansari BA et al; Acta Hydrochim Hydrobiol 15 (3): 301-6 (1987) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Danio rerio (Zebra Danio) adult male and female, weight 0.4 g; Conditions: freshwater, renewal; Concentration: 23.3 umol/L for 96 hr (95% confidence interval: 20.6-26.3 umol/L) /98% purity/
Keizer J et al; Environ Toxicol Chem 12: 1243-50 (1993) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Danio rerio (Zebra Danio) adult, weight 0.4 g; Conditions: freshwater, renewal; Concentration: 8000 ug/L for 96 hr /98% purity formulation/
Keizer J et al; Aquat Toxicol 21 (3/4): 239-54 (1991) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill) weight 1 g; Conditions: freshwater, static, 18 °C, pH 7.1, hardness 44 mg/L CaCO3; Concentration: 362 ug/L for 24 hr (95% confidence interval: 270-480 ug/L) /92% purity formulation/
Mayer FL Jr, Ellersieck MR; USDOI/FWS; Resour Publ No.160: 505 (1986) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill); Concentration: 0.052 ppm for 24 hr /Conditions of bioassay not specified/
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 459
LC50; Species: Lepomis macrochirus (Bluegill sunfish); Concentration: 2.6-3.2 mg/L for 96 hr /Conditions of bioassay not specified in source examined/
Montgomery, J.H.; Agrochemicals Desk Reference 2nd ed. Lewis Publishers, Boca Raton, FL 1997, p. 146
LC50; Species: Lepomis macrochirus (Bluegill) juvenile; Conditions: freshwater, flow through; Concentration: 460 ug/L for 96 hr /92.5% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill); Conditions: freshwater, static; Concentration: 100 ug/L for 96 hr (95% confidence interval: 80-140 ug/L) /48% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill) juvenile; Conditions: freshwater, static; Concentration: 136 ug/L for 96 hr (95% confidence interval: 100-186 ug/L) /91% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill) juvenile; Conditions: freshwater, static; Concentration: 220 ug/L for 96 hr (95% confidence interval: 170-320 ug/L) /48% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill) weight 1 g; Conditions: freshwater, static, 18 °C, pH 7.1, hardness 44 mg/L CaCO3; Concentration: 168 ug/L for 96 hr (95% confidence interval: 120-220 ug/L) /92% purity formulation/
Mayer FL Jr, Ellersieck MR; USDOI/FWS; Resour Publ No.160: 505 (1986) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill); Conditions: freshwater, static, pH 7.7, hardness 192 mg/L CaCO3, alkalinity 138 mg/L CaCO3; Concentration: 120 ug/L for 96 hr /formulation/
Meier EP et al; Bull Environ Contam Toxicol 23 (1-2): 158-64 (1979) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill) age <1 yr; Conditions: freshwater, static, 20 °C, pH 8.2, hardness 192 mg/L CaCO3, alkalinity 138 mg/L CaCO3; Concentration: 170 ug/L for 96 hr /2% purity formulation/
Dennis WHJ et al; Environ Sci Technol 13 (5): 594-8 (1979) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Lepomis macrochirus (Bluegill) age <1 yr; Conditions: freshwater, static, 20 °C, pH 8.2, hardness 192 mg/L CaCO3, alkalinity 138 mg/L CaCO3; Concentration: 530 ug/L for 96 hr /48.2% purity emulsifiable concentrate formulation/
Dennis WHJ et al; Environ Sci Technol 13 (5): 594-8 (1979) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Menidia beryllina (Inland Silverside) age 9 day juvenile; Conditions: saltwater, renewal, 24 °C, pH 7.6, salinity 30 g/L, dissolved oxygen 6.1-6.2 mg/L; Concentration: 3170 ug/L for 24 hr (95% confidence interval: 2950-3410 ug/L) /96% purity formulation/
Thursby GB, Berry WJ; Acute Toxicity of Diazinon to Saltwater Animals- Letter to J Scott and DJ Hansen, Univ of Rhode Island: 10 (1988) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Menidia beryllina (Inland Silverside) age 9 day juvenile; Conditions: saltwater, renewal, 24 °C, pH 7.6, salinity 30 g/L, dissolved oxygen 6.1-6.2 mg/L; Concentration: 2420 ug/L for 48 hr (95% confidence interval: 2110-2770 ug/L) /96% purity formulation/
Thursby GB, Berry WJ; Acute Toxicity of Diazinon to Saltwater Animals- Letter to J Scott and DJ Hansen, Univ of Rhode Island: 10 (1988) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Menidia beryllina (Inland Silverside) age 9 day juvenile; Conditions: saltwater, renewal, 24 °C, pH 7.6, salinity 30 g/L, dissolved oxygen 6.1-6.2 mg/L; Concentration: 1620 ug/L for 72 hr (95% confidence interval: 1410-1850 ug/L) /96% purity formulation/
Thursby GB, Berry WJ; Acute Toxicity of Diazinon to Saltwater Animals- Letter to J Scott and DJ Hansen, Univ of Rhode Island: 10 (1988) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Menidia beryllina (Inland Silverside) age 9 day juvenile; Conditions: saltwater, renewal, 24 °C, pH 7.6, salinity 30 g/L, dissolved oxygen 6.1-6.2 mg/L; Concentration: 1170 ug/L for 96 hr (95% confidence interval: 970-1420 ug/L) /96% purity formulation/
Thursby GB, Berry WJ; Acute Toxicity of Diazinon to Saltwater Animals- Letter to J Scott and DJ Hansen, Univ of Rhode Island: 10 (1988) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout) weight 1.2 g; Conditions: freshwater, static, 13 °C, pH 7.1, hardness 44 mg/L CaCO3; Concentration: 380 ug/L for 24 hr /89% purity formulation/
Mayer FL Jr, Ellersieck MR; USDOI/FWS; Resour Publ No.160: 505 (1986) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout) weight 1.2 g; Conditions: freshwater, static, 13 °C, pH 7.1, hardness 44 mg/L CaCO3; Concentration: 90 ug/L for 96 hr /89% purity formulation/
Mayer FL Jr, Ellersieck MR; USDOI/FWS; Resour Publ No.160: 505 (1986) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout) age 4-12 months, length 2-10 cm; Conditions: freshwater, static, 14 °C, pH 6.8-7.6, dissolved oxygen 10 mg/L; Concentration: 8000 ug/L for 48 hr /formulation, Basudin 60EC/
Bathe R et al; Schriftenr Ver Wasser Boden Lufthyg Berlin - Dahlem37: 241-256 (1973) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout) age 4-12 months, length 2-10 cm; Conditions: freshwater, static, 14 °C, pH 6.8-7.6, dissolved oxygen 10 mg/L; Concentration: 8000 ug/L for 96 hr /formulation, Basudin 60EC/
Bathe R et al; Schriftenr Ver Wasser Boden Lufthyg Berlin - Dahlem37: 241-256 (1973) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout); Conditions: freshwater, static; Concentration: 1650 ug/L for 96 hr (95% confidence interval: 1100-2400 ug/L) /48% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout) juvenile; Conditions: freshwater, static; Concentration: 1800 ug/L for 96 hr (95% confidence interval: 1400-2900 ug/L) /48% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout); Conditions: freshwater, static; Concentration: 400 ug/L for 96 hr (95% confidence interval: 230-700 ug/L) /91% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow Trout); Conditions: freshwater, static; Concentration: 635 ug/L for 96 hr (95% confidence interval: 420-960 ug/L) /23% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow trout); Concentration: 0.380 ppm for 24 hr /Conditions of bioassay not specified/
Verschueren, K. Handbook of Environmental Data of Organic Chemicals. 2nd ed. New York, NY: Van Nostrand Reinhold Co., 1983., p. 459
LC50; Species: Oncorhynchus mykiss (Rainbow Trout) age <24 hr neonate; Conditions: freshwater, static, 22 °C; Concentration: 0.000008 mmol/L for 48 hr /95% purity formulation/
Do Hong LC et al; Environ Toxicol 19 (5): 497-504 (2004) as cited in the ECOTOX database. Available from, as of November 5, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oncorhynchus mykiss (Rainbow trout); Concentration: 16 mg/L for 96 hr
Montgomery, J.H.; Agrochemicals Desk Reference 2nd ed. Lewis Publishers, Boca Raton, FL 1997, p. 146
LC50; Species: Oncorhynchus mykiss (Rainbow Trout); Conditions: freshwater, static, pH 7.7, hardness 192 mg/L CaCO3, alkalinity 138 mg/L CaCO3; Concentration: 1350 ug/L for 96 hr /formulation/
Meier EP et al; Bull Environ Contam Toxicol 23 (1-2): 158-64 (1979). Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oryzias latipes (Medaka) age 24 hr, larva; Conditions: freshwater, renewal, 25 °C; Concentration: 32 uM for 96 hr /99% purity formulation/
Hamm JT et al; Toxicol Sci 61 (2): 304-313 (2001) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oryzias latipes (Medaka) age 1 day, embryo stage 11; Conditions: freshwater, renewal, 25 °C; Concentration: 102 uM for 96 hr /99% purity formulation/
Hamm JT et al; Toxicol Sci 61 (2): 304-313 (2001) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oryzias latipes (Medaka) age 5 day, embryo stage 29; Conditions: freshwater, renewal, 25 °C; Concentration: 103 uM for 96 hr /99% purity formulation/
Hamm JT et al; Toxicol Sci 61 (2): 304-313 (2001) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oryzias latipes (Medaka) age 8 day, embryo stage 34; Conditions: freshwater, renewal, 25 °C; Concentration: 111 uM for 96 hr /99% purity formulation/
Hamm JT et al; Toxicol Sci 61 (2): 304-313 (2001) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oryzias latipes (Medaka) length 2.4-2.9 cm, weight 0.18-0.25 g; Conditions: freshwater, static, 22 °C, pH 7.3-7.4, dissolved oxygen 6.2-6.7 mg/L; Concentration: 4400 ug/L for 48 hr />95% purity/
Tsuda T et al; Chemosphere35(5): 939-949 (1997) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oryzias latipes (Medaka); Conditions: freshwater, static, 10 °C; Concentration: 24000 ug/L for 48 hr /formulation/
Tsuji S et al; J Hyg Chem (Eisei Kagaku) 32 (1): 46-53 (1986) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Oryzias latipes (Medaka); Conditions: freshwater, static, 30 °C; Concentration: 600 ug/L for 48 hr /formulation/
Tsuji S et al; J Hyg Chem (Eisei Kagaku) 32 (1): 46-53 (1986) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
EC50; Species: Pimephales promelas (fathead minnow) age 31 days; Concentration: 9.35 mg/L for 96 hr; Effect: Affected fish lost schooling behavior, were hyperactive and swam in a corkscrew/spiral pattern. They were also over reactive to external stimuli, had increased respiration, convulsions, rigid musculature and hemorrhaging. In addition, they had spinal deformities and lost equilibrium prior to death. /Conditions of bioassay not specified/
Geiger D.L., Call D.J., Brooke L.T. (eds). Acute Toxicities of Organic Chemicals to Fathead Minnows (Pimephales Promelas). Vol. IV. Superior Wisconsin: University of Wisconsin-Superior, 1988., p. 279
LC50; Species: Pimephales promelas (fathead minnow) age 31 days; Concentration: 9.35 mg/L for 96 hr /Conditions of bioassay not specified/
Geiger D.L., Call D.J., Brooke L.T. (eds). Acute Toxicities of Organic Chemicals to Fathead Minnows (Pimephales Promelas). Vol. IV. Superior Wisconsin: University of Wisconsin-Superior, 1988., p. 279
LC50; Species: Pimephales promelas (Fathead Minnow) age 48 hr larva; Conditions: freshwater, renewal, 25 °C; Concentration: 6000 ug/L for 96 hr /100% purity/
Werner I et al; Bull Environ Contam Toxicol 68 (1): 29-36 (2002) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow) age 7 days larva; Conditions: freshwater, static renewal, 20 °C; Concentration: 6600 ug/L for 96 hr /99.4% purity formulation/
Denton DL et al; Environ Toxicol Chem 22 (2): 336-341 (2003) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow) age <24 hr; Conditions: freshwater, static, 20 °C, hardness 60-80 mg/L CaCO3, alkalinity 60-80 mg/L CaCO3; Concentration: 15940 ug/L for 48 hr (95% confidence interval: 12090-19600 ug/L) /5% purity formulation, Ortho Fire Ant Repellant/
Burkepile DE et al; Bull Environ Contam Toxicol 64 (1): 114-21 (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow) larva newly hatched; Conditions: freshwater, flow through, 23.5-26 °C, pH 7.4-7.8, hardness 45.8 mg/L CaCO3, alkalinity 43.1 mg/L CaCO3, dissolved oxygen 6.5-8.4 mg/L; Concentration: 6900 ug/L for 96 hr (95% confidence interval: 6200-7900) /87.1% purity/
Jarvinen AW, Tanner DK; Environ Pollut A 27 (3): 179-195 (1982) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow) larva newly hatched; Conditions: freshwater, static, 23.5-26 °C, pH 7.4-7.8, hardness 45.8 mg/L CaCO3, alkalinity 43.1 mg/L CaCO3, dissolved oxygen 6.5-8.4 mg/L; Concentration: 4300 ug/L for 96 hr (95% confidence interval: 3400-5200 ug/L) /87.1% purity/
Jarvinen AW, Tanner DK; Environ Pollut A 27 (3): 179-195 (1982) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow) larva newly hatched; Conditions: freshwater, static, 23.5-26 °C, pH 7.4-7.8, hardness 45.8 mg/L CaCO3, alkalinity 43.1 mg/L CaCO3, dissolved oxygen 6.5-8.4 mg/L; Concentration: 6100 ug/L for 96 hr (95% confidence interval: 5000-7600 ug/L)
Jarvinen AW, Tanner DK; Environ Pollut A 27 (3): 179-195 (1982) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow) juvenile; Conditions: freshwater, flow through; Concentration: 7800 ug/L for 96 hr /92% purity formulation/
USEPA/OPP, EFED; Pesticide Ecotoxicity Database (2000) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow); Conditions: freshwater, static, pH 7.7, hardness 192 mg/L CaCO3, alkalinity 138 mg/L CaCO3; Concentration: 10300 ug/L for 96 hr /formulation/
Meier EP et al; Bull Environ Contam Toxicol 23 (1-2): 158-64 (1979). Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/
LC50; Species: Pimephales promelas (Fathead Minnow) age <1 yr; Conditions: freshwater, static, 20 °C, pH 8.2, hardness 192 mg/L CaCO3, alkalinity 138 mg/L CaCO3; Concentration: 3700 ug/L for 96 hr /48.2% purity emulsifiable concentrate formulation/
Dennis WHJ et al; Environ Sci Technol 13 (5): 594-8 (1979) as cited in the ECOTOX database. Available from, as of November 6, 2011: https://cfpub.epa.gov/ecotox/

3.6 Ongoing Test Status

The following link will take the user to the National Toxicology Program (NTP) Test Agent Search Results page, which tabulates all of the "Standard Toxicology & Carcinogenesis Studies", "Developmental Studies", and "Genetic Toxicity Studies" performed with this chemical. Clicking on the "Testing Status" link will take the user to the status (i.e., in review, in progress, in preparation, on test, completed, etc.) and results of all the studies that the NTP has done on this chemical.[Available from: http://ntp-apps.niehs.nih.gov/ntp_tox/index.cfm?fuseaction=ntpsearch.searchresults&searchterm=333-41-5]

3.7 FIFRA Requirements (Complete)

Tolerances are established for residues of the insecticide diazinon O,O-diethyl O-(6-methyl-2-(1-methylethyl)-4-pyrimidinyl)phosphorothioate in or on the following food commodities:
Commodity
Almond, hulls
Commodity
Apple
Commodity
Apricot
Commodity
Bean, lima
Commodity
Bean, snap, succulent
Commodity
Beet, garden, roots
Commodity
Beet, garden, tops
Commodity
Blueberry
Commodity
Caneberry subgroup 13-07A
Commodity
Carrot, roots
Commodity
Cattle, fat
Commodity
Cherry, sweet
Commodity
Cherry, tart
Commodity
Cranberry
Commodity
Endive
Commodity
Fig
Commodity
Ginseng
Commodity
Grape
Commodity
Hazelnut
Commodity
Kiwifruit (There are no domestic registrations for kiwifruit as of March 6, 2002)
Commodity
Lettuce
Commodity
Melon
Commodity
Mushroom
Commodity
Nectarine
Commodity
Onion, bulb
Commodity
Onion, green
Commodity
Pea, succulent
Commodity
Peach
Commodity
Pear
Commodity
Pineapple
Commodity
Plum, prune, fresh
Commodity
Radish
Commodity
Rutabaga
Commodity
Spinach
Commodity
Strawberry
Commodity
Tomato
Commodity
Vegetable, brassica, leafy, group 5
Commodity
Watercress
40 CFR 180.153(a) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of August 29, 2011: https://www.ecfr.gov
Tolerances with regional registrations, as defined in part 180.1(l), are established for residues of the insecticide diazinon O,O-diethyl O-(6-methyl-2-(1-methylethyl)-4-pyrimidinyl)phosphorothioate in or on the following food commodities:
Commodity
Almond
Parts per million
0.50
Commodity
Banana
Parts per million
0.20
Commodity
Celery
Parts per million
0.70
Commodity
Cucumber
Parts per million
0.75
Commodity
Parsley, leaves
Parts per million
0.75
Commodity
Parsnip
Parts per million
0.50
Commodity
Pepper
Parts per million
0.5
Commodity
Potato
Parts per million
0.10
Commodity
Squash, summer
Parts per million
0.50
Commodity
Squash, winter
Parts per million
0.75
Commodity
Sweet potato, roots
Parts per million
0.10
Commodity
Swiss chard
Parts per million
0.70
Commodity
Turnip, roots
Parts per million
0.50
Commodity
Turnip, tops
Parts per million
0.75
40 CFR 180.153(c) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of August 29, 2011: https://www.ecfr.gov
EPA has concluded, after completing its assessment of the cumulative risks associated with exposures to all of the OPs /organophosphates/, that: (1) the pesticides covered by the IREDs that were pending the results of the OP cumulative assessment ... are indeed eligible for reregistration; and (2) the pesticide tolerances covered by the IREDs and TREDs that were pending the results of the OP cumulative assessment ... meet the safety standard under Section 408(b)(2) of the FFDCA. Thus, with regard to the OPs, EPA has fulfilled its obligations as to FFDCA tolerance reassessment and FIFRA reregistration, other than product-specific reregistration.
USEPA/OPPTS; Reregistration Eligibility Decision (RED) for Diazinon (333-41-5). Memorandum: Finalization of Interim Reregistration Eligibility Decisions (IREDs) and Interim Tolerance Reassessment and Risk Management Decisions (TREDs) for the Organophosphate Pesticides, and Completion of the Tolerance Reassessment and Reregistration Eligibility Process for the Organophosphate Pesticides p.1 (July 31, 2006). Available from, as of November 20, 2011: https://www.epa.gov/pesticides/reregistration/status.htm
The Agency has completed its assessment of the occupational and ecological risks associated with the use of pesticides containing the active ingredient diazinon, as well as a diazinon-specific dietary risk assessment that has not considered the cumulative effects of organophosphates as a class. Based on a review of these data and public comments on the Agency's assessments for the active ingredient diazinon, EPA has sufficient information on the human health and ecological effects of diazinon to make interim decisions as part of the tolerance reassessment process under FFDCA and reregistration under FIFRA, as amended by FQPA. The Agency has determined that agricultural use of diazinon, based on currently approved labeling, pose occupational and ecological risks. However, the Agency believes that these risks can likely be acceptably mitigated through changes to pesticide labeling and formulations. Accordingly, the Agency has determined that products containing diazinon are eligible for reregistration provided that: (i) additional data that the Agency intends to require confirm this interim decision (ii) the risk mitigation measures outlined in this document are adopted and label amendments are made to reflect these measures; and (iii) cumulative risks considered for the organophosphates support a final reregistration eligibility decision.
USEPA/OPPTS; Interim Reregistration Eligibility Decision (RED) on Diazinon (333-41-5). p.34 USEPA-738-R-04-006 (May 2004). Available from, as of November 20, 2011: https://www.epa.gov/pesticides/reregistration/status.htm
As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their future use. Under this pesticide reregistration program, EPA examines health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether they are eligible for reregistration. In addition, all pesticides must meet the new safety standard of the Food Quality Protection Act of 1996. Diazinon is found on List A, which contains most food use pesticides and consists of the 194 chemical cases (or 350 individual active ingredients) for which EPA issued registration standards prior to FIFRA, as amended in 1988. Case No: 0238; Pesticide type: Insecticide, fungicide (nematicide); Registration Standard Date: 12/25/88; Case Status: OPP is reviewing data from the pesticide's producers regarding its human health and/or environmental effects, or OPP is determining the pesticide's eligibility for reregistration and developing the Reregistration Eligibility Decision (RED) document.; Active ingredient (AI): diazinon; Data Call-in (DCI) Date(s): 10/19/92, 03/03/95, 10/13/95, 03/14/96; AI Status: The producers of the pesticide have made commitments to conduct the studies and pay the fees required for reregistration, and are meeting those commitments in a timely manner.
USEPA/OPP; Status of Pesticides in Registration, Reregistration and Special Review p.109 (Spring, 1998) EPA 738-R-98-002

4 Metabolism / Pharmacokinetics

4.1 Metabolism / Metabolites (Complete)

The main metabolic pathways of degradation of diazinon are: cleavage of the ester bond leading to the hydroxypyrimidine derivatives; transformation of P-S moiety to the P-O derivative; oxidation of isopropyl substituent leading to the corresponding tertiary and primary alcohol derivatives; oxidation of the methyl substituent leading to the corresponding alcohol; glutathione-mediated cleavage of the ester bond leading to a glutathione conjugate.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
/STUDY OF METABOLISM IN RATS OF DIAZINON FOUND THAT/ THE METABOLITES 2-ISOPROPYL-4-METHYL-6-HYDROXYPYRIMIDINE ... /& TWO UNIDENTIFIED METABOLITES/ WHICH WERE EXCRETED IN THE URINE AND FECES, ACCOUNT FOR 70% OF THE DOSE. ... METB IN RATS OF DIAZINON ... LABELLED WITH (14)C, ... 3 METABOLITES WERE LOCATED ON GENERAL METABOLIC PATHWAY BY FOLLOWING THEIR METABOLIC FATE AFTER IV INJECTION. SINCE ACUTE ORAL TOXICITIES OF ALL 3 CMPD ARE LESS THAN 1/10 OF THAT OF DIAZINON, BIOTRANSFORMATION IS ASSOC WITH DETOXICATION.
The Chemical Society. Foreign Compound Metabolism in Mammals. Volume 2: A Review of the Literature Published Between 1970 and 1971. London: The Chemical Society, 1972., p. 286
DIAZINON ... APPEARS TO BE METABOLIZED INTO CORRESPONDING PHOSPHATE IN LACTATING COWS, AND INTO THE HYDROLYTIC PRODUCTS DIETHYL PHOSPHOROTHIOATE AND DIETHYL PHOSPHATE WITH LIBERATION OF 2-HYDROXY-6-ISOPROPYL-4-METHYLPYRIMIDINE /PLUS METABOLITE DIAZOXON/.
The Chemical Society. Foreign Compound Metabolism in Mammals. Volume 1: A Review of the Literature Published Between 1960 and 1969. London: The Chemical Society, 1970., p. 280
AFTER ADMIN OF DIAZINON BY STOMACH TUBE TO SHEEP, HYDROXYDIAZINON WAS FOUND IN TISSUES. DIAZINON, WHEN FED TO SHEEP, WAS METABOLIZED ALSO BY HYDROXYLATION OF C-4 METHYL GROUP. RESIDUES OF THIS & C-1' ISOPROPANOL ANALOG WERE FOUND ... .
Menzie, C. M. Metabolism of Pesticides, An Update. U.S. Department of the Interior, Fish, Wild-life Service, Special Scientific Report - Wildlife No. 184, Washington, DC: U.S. Government Printing Office, l974., p. 154
IN BEAGLE DOG, METAB OF DIAZINON PROCEEDED RAPIDLY. ANALYSES OF URINE INDICATED PRESENCE OF 2 METABOLITES ... 4-HYDROXY-2-ISOPROPYL-6-METHYLPYRIMIDINE & 4-HYDROXY-2-ISOPROPANOL-6-METHYLPYRIMIDINE.
Menzie, C.M. Metabolism of Pesticides, Update II. U.S. Department of the Interior, Fish Wildlife Service, Special Scientific Report - Wildlife No. 2l2. Washington, DC: U.S. Government Printing Office, 1978., p. 109
... DIAZINON ... INCUBATED WITH RAT LIVER MICROSOMES ... /AND/ METABOLITES OBSERVED WERE HYDROXYDIAZINON, DIAZOXON, & HYDROXYDIAZOXON. ARYL-PHOSPHOROTHIONATE BOND CLEAVAGE ALSO OCCURRED WITH PRODUCTION OF DIETHYL PHOSPHOROTHIONIC ACID, 2-ISOPROPYL-4-METHYL-6-HYDROXYPYRIMIDINE, & 2-(2'-HYDROXYISOPROPYL)-4-METHYL-6-HYDROXYPYRIMIDINE.
The Chemical Society. Foreign Compound Metabolism in Mammals Volume 3. London: The Chemical Society, 1975., p. 477
DIAZINON ... METABOLIZED ... OXIDATIVELY BY LIVER MICROSOMES TO GIVE ... DIETHYL PHOSPHORIC ACID.
The Royal Society of Chemistry. Foreign Compound Metabolism in Mammals. Volume 6: A Review of the Literature Published during 1978 and 1979. London: The Royal Society of Chemistry, 1981., p. 303
DIAZINON & DIAZOXON WERE METABOLIZED MORE BY LIVER FRACTIONS OF FRESHWATER FISH THAN BY THOSE OF MARINE FISH. DEGRADATION OF DIAZINON WAS ALSO EQUAL IN ALL THE FRESHWATER FISH. NUCLEUS, MITOCHONDRIA, & MICROSOME FRACTIONS HAD THE HIGHEST DEGRADATION ACTIVITY. THE MICROSOME METABOLITES OF DIAZINON WERE: DIAZOXON (IN ALL FISH STUDIED), ISOPROPENYL DIAZINON & HYDROXYPYRIMIDINE (IN ALL THE FRESHWATER FISH), HYDROXY DIAZINON (CARP, DACE, & CHANNEL CATFISH), & HYDROXYMETHYL DIAZINON (MAJOR METABOLITE IN THE MARINE YELLOWTAIL).
FUJII Y, ASAKA S; BULL ENVIRON CONTAM TOXICOL 29 (4): 455-60 (1982)
FOLLOWING WEEKLY SPRAYING WITH A 0.1% FORMULATION FOR 10 WK, CATTLE STORED DIAZINON IN THEIR FAT AT CONCN UP TO 2.3 PPM ONE DAY AFTER THE LAST SPRAYING, 0.7 PPM 7 DAYS AFTER SPRAYING, BUT NONE AFTER 14 DAYS. ... DIAZINON, SPRAYED ON GRASS @ RATES OF 10 & 100 PPM DISAPPEARED RAPIDLY IN THE SILAGE DURING FERMENTATION WITH ONLY 3% REMAINING AFTER 22 DAYS OF STORAGE. RESIDUES OF DIAZINON ARE NOT DETECTABLE IN BUTTERFAT FROM COWS FED DAILY AT DIETARY LEVELS AS HIGH AS 500 PPM BASED ON DRY WT. ONLY A TRACE OF DIAZINON IS SECRETED IN COWS' MILK FOR 24 HR AFTER DERMAL APPLICATION.
Hayes, Wayland J., Jr. Pesticides Studied in Man. Baltimore/London: Williams and Wilkins, 1982., p. 388
AFTER ADMIN...BY STOMACH TUBE TO A SHEEP, HYDROXYDIAZINON WAS FOUND IN TISSUES.
Menzie, C. M. Metabolism of Pesticides, An Update. U.S. Department of the Interior, Fish, Wild-life Service, Special Scientific Report - Wildlife No. 184, Washington, DC: U.S. Government Printing Office, l974., p. 154

4.2 Absorption, Distribution and Excretion (Complete)

Four laying Leghorn hens were treated with 2-14C-diazinon (specific activity 30.3 uCi/mg) in gelatin capsules for seven consecutive days at daily doses of 1.7 mg/kg body weight, corresponding to a dietary exposure of 25 mg/kg in feed. ... Elimination of most of the administered radioactivity occurred via the excreta, with 78.6% of the total dose being excreted during the study period. Approximately 0.1% of the radioactivity was found in tissues and blood, less than 0.01% appeared in the egg yolks and 0.07% was detected in the egg whites. The residual radioactivity in the tissues amounted to 0.148 mg/kg diazinon equivalents in the kidney, 0.137 mg/kg in blood, 0.11 mg/kg in the liver and 0.01-0.025 mg/kg in the other tissues examined. The residues in the egg yolks ranged from 0.006 mg/kg diazinon equivalents to 0.065 mg/kg while those in the egg whites ranged from 0.038 mg/kg to 0.066 mg/kg. On a whole egg basis, a plateau concentration of 0.047 mg/kg was reached on day 4 of treatment.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
A lactating Hereford cow (body weight 268 kg) was orally treated with a gelatin capsule containing 20 mg/kg 32P-diazinon (specific activity 518 cpm/ug). ... Within 36 hr, approximately 74% of the administered radioactivity was excreted with the urine, 6.5% appeared in the feces and 0.08% was found in the milk. A peak concentration of 2.27 mg/kg diazinon equivalents was reached 18 hr after the administration.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
Two lactating goats were orally treated with (pyrimidine-14C)-diazinon (specific activity 9.7 uCi/mg) in gelatin capsules for four consecutive days at a dose level of 4.5 mg/kg per day, corresponding to a dietary exposure of 100 mg/kg of feed. During the observation period, an average 64.1% of the administered radioactivity was excreted with urine, 10.4% with the feces and 0.31% with the milk. A plateau of radioactivity in the milk was reached after 3 days of dosing at a mean level of 0.46 mg/kg diazinon equivalent. At sacrifice, radioactivity in the blood accounted for 0.2% and the tissues examined accumulated 0.92% of the administered dose. The highest residual radioactivity was detected in the kidney (2.0 mg/kg) and the liver (1.2 mg/kg). The other tissues examined contained 0.23-0.3 mg/kg diazinon equivalents.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
Two female Beagle dogs were intravenously dosed with 0.2 mg/kg (ethoxy-14C)-diazinon (specific activity 3.4 uCi/mg) in 0.7 mL ethanol. ... The half-life of elimination from blood for this second phase was calculated to be 363 min. Approximately 58% of the administered radioactivity was recovered in the urine within 24 hr after the administration. Another two female beagle dogs were orally dosed by capsule with 4.0 mg/kg (ethoxy-14C) diazinon in ethanol. Approximately 85% of the administered radioactivity was recovered within 24 hr after oral administration, with 53% of it occurring in urine.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
Male guinea-pigs treated orally with 45 mg/kg (32P)-diazinon (specific activity 117-197 cpm/mg) in peanut oil, the tissue distribution was determined at 2, 4, 8 and 16 hr after treatment and the excretion of 32P was investigated over an 8-day period. Following oral administration, the compound was rapidly absorbed as shown by a sharp decrease of activity in the stomach and low levels found in the small intestine. Within 16 hr, 46.6% of the administered radioactivity was eliminated in the urine and 0.34% appeared in the feces. The cecum showed a gradual increase of radioactivity, 13-36% of the administered dose accumulating in the cecum over 16 hr after the administration. Irrespective of this accumulation, within 48 hr after dosing, 80% of the administered radioactivity was eliminated in the urine while only 8% was eliminated in the feces.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
Diazinon may be absorbed from the gastrointestinal tract, through the intact skin and following inhalation. Transdermal absorption in humans is low. Diazinon is oxidized by the microsomal enzymes to cholinesterase-inhibiting metabolites such as diazoxon, hydroxydiazoxon, and hydroxydiazinon. Only minimal quantities of metabolites are detectable in milk and eggs. Diazinon and its metabolites do not accumulate in body tissue; 59-95% of an oral dose of diazinon is excreted within 24 hr and 95-98% is excreted within 7 days, mainly in urine.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html
AFTER ORAL ADMIN TO RATS, EXCRETION OF RING & SIDE CHAIN LABELED DIAZINON EXCEEDED 90% AFTER 168 HR. BIOLOGICAL HALF-LIFE VARIED FROM 7 HR IN MALE RATS FOR ETHYL-(14)C-DIAZINON TO 12 HR FOR 2-(14)C-DIAZINON IN MALE & FEMALE RATS.
Menzie, C. M. Metabolism of Pesticides, An Update. U.S. Department of the Interior, Fish, Wild-life Service, Special Scientific Report - Wildlife No. 184, Washington, DC: U.S. Government Printing Office, l974., p. 154
DIAZINON WAS ABSORBED RAPIDLY BY RICE ROOTS WHEN APPLIED TO PADDY WATER & TRANSLOCATED TO LEAF SHEATH & LEAF BLADES. RESIDUES WERE AT MAX 5 DAYS AFTER APPLICATION BUT THEN DECLINED RAPIDLY. THIS LOSS WAS GREATER AFTER SECOND APPLICATION.
Menzie, C. M. Metabolism of Pesticides, An Update. U.S. Department of the Interior, Fish, Wild-life Service, Special Scientific Report - Wildlife No. 184, Washington, DC: U.S. Government Printing Office, l974., p. 156

4.3 Biological Half-Life (Complete)

ORAL DOSE OF ECTOPARASITICIDE, (14)C DIAZINON, WAS RAPIDLY ELIMINATED FROM RAT (BIOLOGICAL HALF-LIFE WAS 12 HR). 80% OF (14)C WAS EXCRETED IN URINE & 18% IN FECES. COMPARABLE EXCRETION PATTERN & LOWER BIOLOGICAL HALF-LIFE OF 9 HR WAS OBTAINED AFTER IV ADMIN OF 3 (14)C METABOLITES OF DIAZINON.
The Chemical Society. Foreign Compound Metabolism in Mammals. Volume 2: A Review of the Literature Published Between 1970 and 1971. London: The Chemical Society, 1972., p. 148
AFTER ORAL ADMIN TO RATS, EXCRETION OF RING & SIDE CHAIN LABELED DIAZINON EXCEEDED 90% AFTER 168 HR. BIOLOGICAL HALF-LIFE VARIED FROM 7 HR IN MALE RATS FOR ETHYL-(14)C-DIAZINON TO 12 HR FOR 2-(14)C-DIAZINON IN MALE & FEMALE RATS.
Menzie, C. M. Metabolism of Pesticides, An Update. U.S. Department of the Interior, Fish, Wild-life Service, Special Scientific Report - Wildlife No. 184, Washington, DC: U.S. Government Printing Office, l974., p. 154
Two female Beagle dogs were intravenously dosed with 0.2 mg/kg (ethoxy-14C)-diazinon (specific activity 3.4 uCi/mg) in 0.7 mL ethanol. ... The half-life of elimination from blood for this second phase was calculated to be 363 min. ...
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html

4.4 Mechanism of Action (Complete)

PURE DIAZINON IS POOR ANTICHOLINESTERASE, BUT IS READILY CONVERTED TO STRONG INHIBITOR UPON STORAGE OR HEATING, PARTICULARLY IN PRESENCE OF TRACE OF MOISTURE. THERMAL DECOMPOSITION OF PURE DIAZINON ... PRODUCTS OBTAINED ARE PYROPHOSPHATES THAT PROBABLY ARE RESPONSIBLE FOR INCR IN ANTICHOLINESTERASE ACTIVITY.
White-Stevens, R. (ed.). Pesticides in the Environment: Volume 1, Part 1, Part 2. New York: Marcel Dekker, Inc., 1971., p. 170
The organothiophosphate diazinon inhibits the target site acetylcholinesterase only after activation to its metabolite diazoxon. Commonly, the toxicity of xenobiotics toward aquatic organisms is expressed as a function of the external concentration and the resulting effect on the individual level after fixed exposure times. This approach does not account for the time dependency of internal processes such as uptake, metabolism, and interaction of the toxicant with the target site. Here, ...a mechanistic toxicodynamic model for Daphnia magna and diazoxon /is developed/, which accounts for the inhibition of the internal target site acetylcholinesterase and its link to the observable effect, immobilization, and mortality. The model was parametrized by experiments performed in vitro with the active metabolite diazoxon on enzyme extracts and in vivo with the parent compound diazinon. The mechanism of acetylcholinesterase inhibition was shown to occur irreversibly in two steps via formation of a reversible enzyme-inhibitor complex. The corresponding kinetic parameters revealed a very high sensitivity of acetylcholinesterase from D. magna toward diazoxon, which corresponds well with the high toxicity of diazinon toward this species. Recovery of enzyme activity but no recovery from immobilization was observed after in vivo exposure to diazinon. The toxicodynamic model combining all in vitro and in vivo parameters was successfully applied to describe the time course of immobilization in dependence of acetylcholinesterase activity during exposure to diazinon. The threshold value for enzyme activity below which immobilization set in amounted to 40% of the control activity. Furthermore, the model enabled the prediction of the time-dependent diazoxon concentration directly present at the target site.
Kretschmann A et al; Environ Sci Technol 45 (11): 4980-7 (2011)

5 Pharmacology

5.1 Therapeutic Uses (Complete)

VET: Used against ... flies and ticks in veterinary practice.
Worthing, C.R. and S.B. Walker (eds.). The Pesticide Manual - A World Compendium. 8th ed. Thornton Heath, UK: The British Crop Protection Council, 1987., p. 248

5.2 Interactions (Complete)

To investigate possible joint toxic effects of diazinon, propoxur and bisphenol A (BPA) on proliferation of /mouse/ RAW264.7 cells in vitro. Cytotoxicity was assessed by MTT assay. The median inhibiting concentration values (IC50) and 95% confidence interval (CI) of diazinon, propoxur and BPA individually and in mixture (mixed according to ratio of IC50) were established by weighted probit method. The types of toxic interaction of diazinon and BPA and propoxur and BPA were assessed by three methods commonly used for binary mixtures, which were Additional Index Method, Equivalent Effect Curve Method and Logistic Regression Method. After 24-hr expoxure, the IC50 and 95% CI of diazinon, propoxur and BPA to RAW264.7 cells were 194.1 microg/mL (173.4 microg/mL-217.4 microg/mL), 448.4 mg/L (358.2 microg/mL-573.2 microg/mL), and 37.5 microg/mL (35.3 microg/mL-39.9 microg/mL), respectively. Those of mixtures of diazinon and BPA and propoxur and BPA were 168.8 microg/mL (160.1 microg/mL-178.2 microg/mL) and 253.4 microg/mL (236.0-273.0 microg/mL). In the interaction assessment, three methods all demonstrated an antagonistic action of diazinon and BPA and an addition action of propoxur and BPA. ...
Tan X et al; Wei Sheng Yan Jiu. 40 (2): 191-5 (2011)

6 Environmental Fate & Exposure

6.1 Environmental Fate / Exposure Summary

Diazinon's production and use as an insecticide is expected to result in its direct release to the environment; all residential uses have been cancelled. If released to air, a vapor pressure of 9.0X10-5 mm Hg at 25 °C indicates diazinon will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase diazinon will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 1.8 hrs. Particulate-phase diazinon will be removed from the atmosphere by wet and dry deposition. Diazinon absorbs light in the environmental UV spectrum and therefore may be susceptible to direct photolysis by sunlight. The detection of diazinon in lake waters in Canada (arctic, sub-arctic and remote locations) at long distances (hundreds of kilometers) from known source areas indicates diazinon can undergo long range atmospheric transport. If released to soil, diazinon is expected to have moderate-to-low mobility based upon a range of experimental Kocs from 191-1842. Volatilization from moist soil surfaces is not expected to be an important fate process based upon a Henry's Law constant of 1.17X10-7 atm-cu m/mole. Biodegradation is a major fate process in soils. Half-lives of <1, 2, and 5 weeks have been reported in non-sterile soils as compared to half-lives of 6, 6.5, and 12.5 weeks in sterile soils; at 7.5 and 20 °C, dissipation was approximately 65-95% in non-sterile soil and only 20-25% in sterile soil. Overall persistence in soils has been reported to be 3 to 14 weeks. Field dissipation half-lives are reported to range from 2.8 to 48 days with an average of 7 days. Disappearance of diazinon in soil is a combined effect of biotic and abiotic hydrolysis with hydrolysis rates depending on pH (especially important in acidic organic soil). The photolysis rate constant of diazinon on soil at 25 °C is reported to be 0.151 per day which corresponds to a half-life of 4.6 days. Soil degradation of diazinon involves oxidation to the phosphate (diazoxon) and hydrolysis to 2-isopropyl-6-methyl-pyrimidinol. If released into water, diazinon is expected to adsorb to suspended solids and sediment based upon the experimental Kocs. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's Henry's Law constant. Hydrolysis half-lives for diazinon at 25 °C are 12 days (pH 5), 139 days (pH 7) and 77 days (pH 9). Photolysis may be an important degradation process; 36% of diazinon photolyzed in a pH 7 buffer solution exposed to light with wavelengths >290 nm in a period of 24 hrs. The photolysis rate constant in water at 25 °C is reported to be 0.136 per day which corresponds to a half-life of 5.1 days. A range of experimental BCFs from 3-200 suggests bioconcentration in aquatic organisms is low to moderate. Occupational exposure to diazinon may occur through inhalation and dermal contact with this compound at workplaces where diazinon is produced or used. Monitoring data indicate that the general population may be exposed to diazinon during application following residential use as an insecticide, inhalation of ambient air, and ingestion of contaminated food and drinking water. (SRC)

6.2 Probable Routes of Human Exposure (Complete)

NIOSH (NOES Survey 1981-1983) has statistically estimated that 39,342 workers (3,216 of these were female) were potentially exposed to diazinon in the US(1). The NOES Survey does not include farm workers(SRC). Occupational exposure to diazinon may occur through inhalation and dermal contact with this compound at workplaces where diazinon is produced or used(SRC). The workshop air of a production facility in Budapest, Hungary contained 0.45 mg/cu m of diazinon(2). Eight-hour personal breathing air sampling of 13 pest control operators gave mean diazinon concentrations of not detectable to 41.0 ug/cu m, group average 6.29 ug/cu m(4). Area sampling of 2 homes during pesticide application in attics showed mean 8-hr time weighted concentration of 0.3 ug/cu m(5). The potential respiratory and dermal exposure during air blast spraying fruit orchards was measured as 0.06 mg/hr and 23.4 mg/hr, respectively(3). Among pest control operators, air sampling for 14 subjects gave results of not detected to 41 ug/cu m(4). The general population may be exposed to diazinon during application following residential use as an insecticide. Monitoring data indicate that the general population may also be exposed to diazinon via inhalation of ambient air and ingestion of contaminated food and drinking water(SRC).
(1) NIOSH; NOES. National Occupational Exposure Survey conducted from 1981-1983. Estimated numbers of employees potentially exposed to specific agents by 2-digit standard industrial classification (SIC). Available from, as of Mar 21, 2012: https://www.cdc.gov/noes/
(2) Kiraly J et al; Arch Environ Contam Toxicol 8: 309-19 (1979)
(3) Wolfe HR; pp. 137-63 in Air Pollut From Pest and Agric Processes, Lee RI Jr, ed. Cleveland, OH: CRC Press (1976)
(4) Hayes AL et al; Am Ind Hyg Assoc J 41: 568-75 (1980)

6.3 Artificial Pollution Sources (Complete)

Diazinon's production may result in its release to the environment through various waste streams; its use as an insecticide(1) will result in its direct release to the environment(SRC). All residential uses have been cancelled(2).
(1) MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
(2) USEPA/OPPTS; Reregistration Eligibility Decisions (REDs) Database on Diazinon (333-41-5). USEPA-738-R-04-006. Available from, as of Sept 7, 2011: https://www.epa.gov/pesticides/reregistration/status.htm

6.4 Environmental Fate (Complete)

TERRESTRIAL FATE: Based on a classification scheme(1), a range of experimental Koc values of 191-1,842(2,3), indicates that diazinon is expected to have moderate-to-low mobility in soil(SRC). Volatilization of diazinon from moist soil surfaces is not expected to be an important fate process(SRC) given a Henry's Law constant of 1.17X10-7 atm-cu m/mole(4). Diazinon is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 9.0X10-5 mm Hg(5). Biodegradation is expected to be a major fate process in soils(SRC). Half-lives of <1, 2, and 5 weeks have been reported in non-sterile soils as compared to half-lives of 6, 6.5, and 12.5 weeks in sterile soils(6,7); at 7.5 and 20 °C, dissipation was approximately 65-95% in non-sterile soil and only 20-25% in sterile soil over 120 days(8). Overall persistence in soils has been reported to be 3 to 14 weeks(9). Field dissipation half-lives are reported to range from 2.8 to 48 days with an average of 7 days(3). Laboratory studies in top soil and subsoil at 20 and 7.5 °C have reported soil half-lives of 7 to 25 days(10); disappearance of diazinon was a combined effect of biotic and abiotic hydrolysis with hydrolysis rates depending on pH (especially important in acidic organic soil)(11). Hydrolysis of diazinon was reported to be more rapid in soils than in water; 11% of diazinon applied to Poygan sand was degraded per day(11). Diazinon absorbs light at wavelengths >290 nm(12), and therefore is susceptible to direct photolysis(SRC). The percent photolysis (difference between samples exposed to light closely approximating that of sunlight and covered samples) in 24 hrs was reported to be 51% on moist soil surfaces and 44% on dry soil surfaces at 45 °C, and 36% in pH 7.0 buffer solutions at 25 °C(13). The photolysis rate constant of diazinon on soil at 25 °C is reported to be 0.151 per day(3) which corresponds to a half-life of 4.6 days(SRC). Soil degradation of diazinon involves oxidation to the phosphate (diazoxon)(5) and hydrolysis to 2-isopropyl-6-methyl-pyrimidinol(14).
(1) Swann RL et al; Res Rev 85: 17-28 (1983)
(2) Sharom MS et al; Water Res 14: 1095-100 (1980)
(3) USDA; ARS Pesticide Properties Database (last updated May 1999) on Diazinon (333-41-5). Available from, as of Sept 13, 2011: https://www.ars.usda.gov/Services/docs.htm?docid=14199
(4) Fendinger NJ, Glotfelty DE; Environ Sci Technol 22: 1298-93 (1988)
(5) MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
(6) Miles JRW et al; Bull Environ Contam Toxicol 22: 312-8 (1979)
(7) Getzin LW; J Econ Entomol 61: 1560-5 (1968)
(8) Sarmah AK et al; J Environ Sci Health Part B 44: 325-336 (2009)
(9) Ahmed N et al; Phytoprotection 53: 71-4 (1972)
(10) Sarmah AK et al; J Environ Sci Health Part B 44: 325-336 (2009)
(11) Sanborn JR et al; The Degradation of Selected Pesticides in Soil: A Review of the Published Literature NTIS PB- 272 353 (1977)
(12) Gore RC et al; J Assoc Off Anal Chem 54: 1040-82 (1971)
(13) Burkhard N, Guth JA; Pestic Sci 10: 313-9 (1979)
(14) Bavcon M et al; Chemosphere 50: 595-601 (2003)
TERRESTRIAL FATE: ... Diazinon is relatively nonpersistent in soil. Most diazinon applied is lost from soil through chemical and biologic degradation within about 2 months of application. ... about 46% of diazinon added to neutral aqueous solution remained after 2 wks.
National Research Council. Drinking Water & Health Volume 1. Washington, DC: National Academy Press, 1977., p. 609
TERRESTRIAL FATE: Degraded in soil to 10% in 3 weeks
Spencer, E. Y. Guide to the Chemicals Used in Crop Protection. 7th ed. Publication 1093. Research Institute, Agriculture Canada, Ottawa, Canada: Information Canada, 1982., p. 178
AQUATIC FATE: Based on a classification scheme(1), a range of Koc values of 191-1,842(2,3), indicates that diazinon is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(4) based upon a Henry's Law constant of 1.17X10-7 atm-cu m/mole(5). According to a classification scheme(6), a range of BCFs from 3-200(7-11), suggests the potential for bioconcentration in aquatic organisms is low-to-moderate(SRC). Hydrolysis may be a significant fate process(SRC) with reported half-lives of 31 days (pH 5), 185 days (pH 7.4), and 136 days (pH 9) at 20 °C(12), 2-3 weeks in distilled water at pH 6 at room temperature(13), and 12 days (pH 5), 139 days (pH 7) and 77 days (pH 9) at 25 °C(3). Major products of hydrolysis were 2-isopropyl-4-methyl-6-hydroxypyrimidine and diethyl thiophosphoric acid or diethyl phosphoric acid(12). Photolysis is an important degradation process(SRC); 36% of diazinon photolyzed in a pH 7 buffer solution exposed to light with wavelengths >290 nm in a period of 24 hrs(14). The photolysis rate constant in water at 25 °C is reported to be 0.136 per day(3) which corresponds to a half-life of 5.1 days(SRC). Diazinon disappeared more quickly from unsterilized natural water (12 weeks) than from unsterilized distilled or sterilized natural water (>16 weeks), suggesting that degradation is both biological and chemical in nature in natural waters(15). Using water samples from two nursery recycling ponds as inoculum at 22 °C, half-lives ranged from 34.4 to 76.6 days in non-sterile water and 69.5 to 134.4 days sterile water(16).
(1) Swann RL et al; Res Rev 85: 17-28 (1983)
(2) Sharom MS et al; Water Res 14: 1095-100 (1980)
(3) USDA; ARS Pesticide Properties Database (last updated May 1999) on Diazinon (333-41-5). Available from, as of Sept 13, 2011: https://www.ars.usda.gov/Services/docs.htm?docid=14199
(4) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 4-9, 15-1 to 15-29 (1990)
(5) Fendinger NJ, Glotfelty DE; Environ Sci Technol 22: 1298-93 (1988)
(6) Franke C et al; Chemosphere 29: 1501-14 (1994)
(7) Kanazawa J; Bull Environ Contam Toxicol 20: 613-7 (1978)
(8) Verschueren K; Handbook of Environmental Data on Organic Chemicals. 2nd ed New York, NY: Van Nostrand Reinhold pp. 456-9 (1996)
(9) Kenaga EE; Ecotox Env Safety 4: 24-38 (1980)
(10) Seguchi K, Asaka S; Bull Environ Contam Toxicol 27: 244-9 (1981)
(11) Zaroogian GE et al; Environ Toxicol Chem 4: 3-12 (1985)
(12) Gomaa HM et al; Res Rev 29: 171-90 (1969)
(13) Cowart RP et al; Bull Environ Contam Toxicol 6: 231-4 (1971)
(14) Burkhard N, Guth JA; Pestic Sci 10: 313-9 (1979)
(15) Sharom MS et al; Water Res 14: 1089-93 (1980)
(16) Lu J et al; J Agric Food Chem 54: 2658-2663 (2006)
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), diazinon, which has a vapor pressure of 9.0X10-5 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere(SRC). Vapor-phase diazinon is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 1.8 hrs(SRC), calculated from its experimental rate constant of 2X10-10 cu cm/molecule-sec(3). Particulate-phase diazinon may be removed from the air by wet and dry deposition(SRC). Diazinon absorbs light in the environmental spectrum(4) and has the potential for direct photolysis in the atmosphere(SRC). The detection of diazinon in lake waters in Canada (arctic, sub-arctic and remote locations) at long distances (hundreds of kilometers) from known source areas indicates diazinon can undergo long range atmospheric transport(5).
(1) Bidleman TF; Environ Sci Technol 22: 361-367 (1988)
(2) MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
(3) Hebert VR et al; J Agric Food Chem 48: 1922-1928 (2000)
(4) Gore RC et al; J Assoc Off Anal Chem 54: 1040-82 (1971)
(5) Muir DCG et al; Environ Toxicol Chem 23: 2421-2432 (2004)

6.5 Environmental Biodegradation (Complete)

AEROBIC: Half-lives reported for diazinon in sterile (non-sterile) soils were 12.5 weeks (<1 week) in sandy loam and 6.5 weeks (2 weeks) in organic soil(1). Diazinon disappeared more quickly from unsterilized natural water (12 weeks) than from unsterilized distilled or sterilized natural water (>16 weeks), suggesting that degradation is both biological and chemical in nature in natural waters(2). Percent theoretical biological oxygen demand (BOD) was 16% for diazinon incubated with municipal sewage for 7.5-8.3 days(3). Diazinon, present at 100 mg/L, reached 0% of its theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test(4).
(1) Miles JRW et al; Bull Environ Contam Toxicol 22: 312-8 (1979)
(2) Sharom MS et al; Water Res 14: 1089-93 (1980)
(3) Rosenberg A et al; Microbial Degradation of Pesticides, Annual Report Contract. Ithaca, NY: Cornell Univ N00014-78-C-004 (1979)
(4) NITE; Chemical Risk Information Platform (CHRIP). Biodegradation and Bioconcentration. Tokyo, Japan: Natl Inst Tech Eval. Available from, as of Sept 14, 2011: https://www.safe.nite.go.jp/english/db.html
AEROBIC: Using water samples from two nursery recycling ponds as inoculum, the first-order half-life of diazinon at 10 °C ranged from 63.1 to 122.9 days under non-sterile conditions(1); under sterile conditions at 10 °C, the half-life range was 178.3 to 268.5 days(1); at 22 °C, half-lives ranged from 34.4 to 76.6 days under non-sterile conditions(1); under sterile conditions at 22 °C, the half-life range was 69.5 to 134.4 days(1). In laboratory dissipation studies using sterile and non-sterile New Zealand soils as inoculum over a 120-day incubation period, dissipation of diazinon was faster in the non-sterile soil indicating microbial degradation as the major dissipation pathway(2); at 7.5 and 20 °C, dissipation was approximately 65-95% in non-sterile soil and only 20-25% in sterile soil over 120 days(2).
(1) Lu J et al; J Agric Food Chem 54: 2658-2663 (2006)
(2) Sarmah AK et al; J Environ Sci Health Part B 44: 325-336 (2009)
PURE CULTURE: From submerged soil & rice paddies, microorganisms capable of decomposing diazinon ... fall into 3 categories: sole C source- Flavobacterium sp; synergism- Arthrobacter sp plus Streptomyces sp; co-metabolism- Arthrobacter sp, Corynebacterium sp, Pseudomonas melophthora, Streptomyces sp, Trichoderma viride.
Menzie, C.M. Metabolism of Pesticides, Update II. U.S. Department of the Interior, Fish Wildlife Service, Special Scientific Report - Wildlife No. 2l2. Washington, DC: U.S. Government Printing Office, 1978., p. 109

6.6 Environmental Abiotic Degradation (Complete)

The rate constant for the vapor-phase reaction of diazinon with photochemically-produced hydroxyl radicals has been experimentally determined to be 2X10-10 cu cm/molecule-sec(1). This corresponds to an atmospheric half-life of approximately 1.8 hrs at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(SRC). Half-lives for hydrolysis in buffered distilled water at 20 °C were 31 days (pH 5.0), 185 days (pH 7.4), and 136 days (pH 9.0); major products of hydrolysis were 2-isopropyl-4-methyl-6-hydroxypyrimidine and diethyl thiophosphoric acid or diethyl phosphoric acid(2). Half-lives reported for hydrolysis of diazinon in sterile water-ethanol (99:1) and phosphate buffer at 25 °C were 14 days (pH 5.0), 54.6 days (pH 6.0), 70 days (pH 7.0) and 54 days (pH 8.0)(3). The aqueous hydrolysis rate constants for diazinon at 25 °C are reported to be 0.0578 (pH 5), 0.0050 (pH 7) and 0.009 (pH 9) per day(4), corresponding to half-lives of 12, 139 and 77 days, respectively(SRC). The aqueous decomposition half-lives of diazinon at 20 °C are reported to be 11.77 hr (pH 3.1), 185 days (pH 7.4) and 6.0 days (pH 10.4)(5). Hydrolysis of diazinon was reported to be more rapid in soil than in water, and was extremely rapid in water at pH 2, but was slow at pH 6; 11% degradation/day was reported in Poygan sand and 6%/day in Ella sediments(6). Diazinon absorbs light at wavelengths > 290 nm(7), and therefore may be susceptible to direct photolysis(SRC). The photolysis rate constant of diazinon on soil at 25 °C is reported to be 0.151 per day(4) which corresponds to a half-life of 4.6 days(SRC); the photolysis rate constant in water at 25 °C is reported to be 0.136 per day(4) which corresponds to a half-life of 5.1 days(SRC). The percent photolysis (difference between samples exposed to light closely approximating that of sunlight and covered samples) in 24 hrs was reported to be 51% on moist soil surface and 44% on dry soil surfaces at 45 °C, and 36% in pH 7.0 buffer solutions at 25 °C(8). Photolytic degradation of diazinon was catalyzed by anthraquinone and to a lesser extent by pentachlorophenol(9). In laboratory studies using a dry sandy soil, diazinon had a dissipation half-life of 830 hr with irradiation and 900 hr in dark controls(10); dissipation in moist soil was 4 to 6.5 times faster, probably due to hydrolysis(10).
(1) Hebert VR et al; J Agric Food Chem 48: 1922-1928 (2000)
(2) Gomaa HM et al; Res Rev 29: 171-90 (1969)
(3) Chapman RA, Cole CM; J Environ Sci Health B17: 487-504 (1982)
(4) USDA; ARS Pesticide Properties Database (last updated May 1999) on Diazinon (333-41-5). Available from, as of Sept 13, 2011: https://www.ars.usda.gov/Services/docs.htm?docid=14199
(5) MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
(6) Sanborn JR et al; The Degradation of Selected Pesticides in Soil: A Review of the Published Literature NTIS PB-272 353 (1977)
(7) Gore RC et al; J Assoc Off Anal Chem 54: 1040-82 (1971)
(8) Burkhard N, Guth JA; Pestic Sci 10: 313-9 (1979)
(9) Ivie GW, Casida JE; J Agric Food Chem 19: 410-6 (1971)
(10) Graebing P, Chib JS; J Agric Food Chem 52: 2606-2614 (2004)
The half-life of diazinon in nonsterile water decreases as the temperature increases from 6 °C to 22 °C(1). At 6 °C in the dark, the half-lives (days) for ultrapure water, river water, filtered river water, and seawater were 144, 181, 132, and 125, respectively(1). At 22 °C in the dark, the half-lives (days) of diazinon in ultrapure water, river water, filtered river water, and seawater were 69, 80, 52, and 50, respectively(1). The lower half-lives in filtered river water compared to unfiltered results from slight adsorption of diazinon to particulate matter(1). At 22 °C and illuminated under sunlight, the half-lives(days) of diazinon in river water and seawater were 43 and 47, respectively(1). A larger decrease in half-life for river water results from a greater concn of humic acid photosensitizers in river water which may be responsible for the degradation of diazinon(1).
(1) Lartiges SB, Garrigues PP; Environ Sci Technol 29: 1246-54 (1995)
In soil, hydrolysis was major mechanism in diazinon degradation ... 3 weekk treatment of sultan silt loam with diazinon, in addition to diazinon, 2-isopropyl-4-methyl-6-hydroxypyrimidine was identified. Oxon analog was unstable in soil & was not detected.
Menzie, C.M. Metabolism of Pesticides. U.S. Department of the Interior, Bureau of Sport Fisheries and Wildlife, Publication 127. Washington, DC: U.S. Government Printing Office, 1969., p. 143
On field sprayed kale ... hydroxy-diazinon ... detected. Hydroxy-diazinon probably arose from natural uv irradiation of diazion.
Menzie, C. M. Metabolism of Pesticides, An Update. U.S. Department of the Interior, Fish, Wild-life Service, Special Scientific Report - Wildlife No. 184, Washington, DC: U.S. Government Printing Office, l974., p. 154

6.7 Environmental Bioconcentration (Complete)

BCF values were measured in the following species: topmouth gudgeon (Pseudodorasbora parva), 152, silver crucian carp (Cyprinus auratus), 36.6, carp (Cryprinus carpio), 65.1, guppy (Lebisters reticuatus) 17.5, crayfish (Procambarus clarkii), 4.9, red snail (Indoplanorbis exustus), 17.0, pond snail (Cipangopoludina malleata), 5.9(1); a fish (Fundulus heteroclutus), 10(2); species unreported, 35(3); carp, 120, rainbow trout, 63, loach, 26, shrimp, 3(4); sheepshead minnow, 200(5); eel(Anguilla anguilla) muscle and liver, 1600 and 800, respectively(6); perch 27(7); earthworm 8(8); fish from the Philipines, 12(9). According to a classification scheme(10), the range of experimental BCFs suggests the potential for bioconcentration in aquatic organisms is low to moderate(SRC).
(1) Kanazawa J; Bull Environ Contam Toxicol 20: 613-7 (1978)
(2) Verschueren K; Handbook of Environmental Data on Organic Chemicals. 2nd ed New York, NY: Van Nostrand Reinhold pp. 456-9 (1996)
(3) Kenaga EE; Ecotox Env Safety 4: 24-38 (1980)
(4) Seguchi K, Asaka S; Bull Environ Contam Toxicol 27: 244-9 (1981)
(5) Zaroogian GE et al; Environ Toxicol Chem 4: 3-12 (1985)
(6) Sancho E et al; Bull Environ Contam Toxicol 50: 578-85 (1993)
(7) El Arab AE et al; Chemosphere 21: 193-9 (1990)
(8) Connell DW, Markwell RD; Chemosphere 20: 91-100 (1990)
(9) Bajet CM; pp 271-310 in Pesticide residues in coastal tropical ecosystems. Taylor & Francis (2003)
(10) Franke C et al; Chemosphere 29: 1501-14 (1994)
The bioconcentration and excretion of diazinon was studied for the fresh-water fish, willow shiner (Gnathopogon caerulescens) in continuous flow-through tanks. A stock solution of diazinon was diluted to give measured concentration of 2.4-3.3 ug/L in the test tanks. Fish were exposed to the test solutions for 0 to 168 hr. For excretion of the test chemicals fish from the test tanks were transferred to tanks containing clean water. The measured concentration of the diazinon excreted from fish was < 0.02 ug/L after 10 hr. Determination of diazinon in whole bodies of fish was carried out at each sampling time of the bioconcentration and excretion experiments. Avg recoveries were 86.7% for diazinon. Bioconcentration factors for diazinon in whole body of fish ranged from 131.3 at 6 hr to 274.4 at 168 hr. The excretion rate constant/hr for diazinon was 0.07 and the half-life in hr was 9.9.
Tsuda T et al; Toxicol Environ Chem 24 (3): 185-90 (1989)

6.8 Soil Adsorption / Mobility (Complete)

The Koc for diazinon ranged from 40-432, and averaged 191 for 3 soils(1); in one sediment, the Koc was 250(1). For sandy loam(2.0% OM, pH 5.4), silt loam(1.4% OM, pH 7.0), silt loam(1.8% OM, pH 6.5) and sand(1.4% OM, pH 7.0), the Kocs were 1,539, 1,007, 1,653, and 1,842, respectively, with a recommended value of 1520(2). The Koc for diazinon was found to be 1589 in an Hungarian brown forest soil(3). The Koc for diazinon in two New Zealand topsoils was 165.22 and 324.49(4); the Koc in a New Zealand subsoil was 1447.47(4). According to a classification scheme(5), these experimental Koc values suggest that diazinon is expected to have moderate to low mobility in soil(SRC). Diazinon was given a leaching index of 2.0 (<20 cm movement/yr with 150 cm of annual rainfall)(6). Diazinon is reported to be fairly strongly adsorbed onto soil with low mobility(7).
(1) Sharom MS et al; Water Res 14: 1095-100 (1980)
(2) USDA; ARS Pesticide Properties Database (last updated May 1999) on Diazinon (333-41-5). Available from, as of Sept 13, 2011: https://www.ars.usda.gov/Services/docs.htm?docid=14199
(3) Nemeth-Konda L et al; Chemosphere 48: 545-552 (2002)
(4) Sarmah AK et al; J Environ Sci Health Part B 44: 325-336 (2009)
(5) Swann RL et al; Res Rev 85: 17-28 (1983)
(6) Haque R, Freed VH; Res Rev 52: 89-116 (1974)
(7) MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
Soil sorption constants based on the organic carbon content of 15 pesticides were measured using 2 soils (clay loam and high clay) at 0.01, 0.1 and 1.0 ppm pesticide. The soil sorption coefficients ((ug pesticide/g soil)/(ug pesticide/g water)) for diazinon were 13.9 in clay loam and 2.4 in high clay soil. The soil sorption constants were 327 and 175 respectively, with a mean of 251. Significant correlations were found between organic carbon content and water solubility, octanol/water partition coefficient, retention time in reversed phase high pressure liquid chromatography and molecular wt(1). In sediment-water partition studies, the sorption of diazinon was found to increase with time over a 28-day test period(1); in sediments from Bonita Creek (Orange County CA), the calculated Koc increased from 46 (on day 0) to 497 (on day 28); in sediments from the San Diego Creek (Orange County CA), the calculated Koc increased from 113 (on day 0) to 777 (on day 28)(2).
(1) Kanazawa J; Environ Toxicol Chem 8: 477-84 (1989)
(2) Bondarenko S, Gan J; Environ Toxicol Chem 23: 1809-1814 (2004)

6.9 Volatilization from Water / Soil (Complete)

ABOUT 50% OF DIAZINON WAS LOST FROM TREATED RICE PLANTS WITHIN 9 DAYS THROUGH VOLATILIZATION FROM PADDY WATER & TRANSPIRATION FROM LEAVES. LESS THAN 10% OF RADIOACTIVITY REMAINED IN PLANTS AS PARENT CMPD.
Menzie, C. M. Metabolism of Pesticides, An Update. U.S. Department of the Interior, Fish, Wild-life Service, Special Scientific Report - Wildlife No. 184, Washington, DC: U.S. Government Printing Office, l974., p. 156
The Henry's Law constant for diazinon has been measured as 1.17X10-7 atm-cu m/mole at 23 °C(1) and 6.25X10-8 atm-cu m/mole at 25 °C(2). These Henry's Law constants indicate that diazinon is expected to be essentially nonvolatile from water surfaces(3). Diazinon is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 9.0X10-5 mm Hg(4). The percent of applied diazinon which evaporated from soil in a lysimeter experiment was 0.5%/week(5). Diazinon was given a vaporization from soil index of 3.0 (3.5-6.5 kg/ha/yr, or more)(6). A reported measured cumulative volatilization of diazinon from a fallow soil was only 0.13% of applied dose(7).
(1) Fendinger NJ, Glotfelty DE; Environ Sci Technol 22: 1298-93 (1988)
(2) Feigenbrugel V et al; Chemosphere 57: 319-327 (2004)
(3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 15-1 to 15-29 (1990)
(4) MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
(5) Jenkins D et al; Water Res 12: 713-23 (1978)
(6) Haque R, Freed VH; Res Rev 52: 89-116 (1974)
(7) Ferrari F et al; J Environ Qual 32: 1623-1633 (2003)

6.10 Environmental Water Concentrations (Complete)

GROUNDWATER: Diazinon (dissolved) was detected in groundwater in the United States at 90 of 4,467 stations at an average concentration of 0.071 ug/L(1). Diazinon was detected in 1.30% of 2459 groundwater samples (maximum concentration of 1.6 ug/L) collected between 1992 and 1996 at nearly 1400 sites around the US(2).
(1) USEPA; Envirofacts. National Contaminant Occurrence Database (NCOD) on Diazinon. Available from Database Query page at https://www.epa.gov:9966/ncod/rpt_options_pws_pkg.national_state_selection as of Sept 13, 2000
(2) Kolpin DW etal; Ground Water 38: 858-63 (2000)
DRINKING WATER: Diazinon was not detected or quantified in 54 drinking water wells in California(1). Diazinon was not detected (<1 parts per trillion) in tap water from Ottawa, Ontario, Canada(2). Japanese tap water contained 0.9-4.7 parts per trillion diazinon(3). Diazinon was not detected (detection limit not reported) in 19 drinking water treatment plants samples collected between 2006 and 2007 at locations in the US(4).
(1) Maddy KT et al; A Study of Well Water in Selected California Communities for Residues of 1,3-Dichloropropopene, Chlorallyl Alcohol and 49 OrganoPhosphate or Chlorinated Hydrocarbon Pesticides. CA Dept Food Agric HS-1002 (1982)
(2) LeBel GL et al; J Assoc Off Anal Chem 62: 241-9 (1979)
(3) Adachi K et al; Hyogo-Ken Eisei Kenkyusho Kenkyu Hokoku 19: 1-6 (1984)
(4) Benotti MJ et al; Environ Sci Technol 43: 597-603 (2009)
SURFACE WATER: Diazinon (dissolved) was detected in estuary (2 of 2 stations), lake/reservoir (25 of 159 stations), spring (8 of 76 stations), and other surface water (3,213 of 12,034 stations) in the United States at average concentrations of 0.045, 0.027, 0.044, and 0.085 ug/L, respectively(1). Diazinon was detected in 21,978 whole water samples from the USEPA STORET database with a range and average concentration of 0-33.4 ppm and 1.7 ppb, respectively(2). Diazinon was detected in 359 filtered water samples from the USEPA STORET database with a range and average concentration of 0-1.0 ppb and 0.031 ppb, respectively(2). In the National Surface Water Monitoring Program from 1976 to 1980, diazinon was detected in 1.2% samples with a maximum concentration of 2.4 ppb(3). In selected streams in the US between 1968 to 1971,1.6% of 448 samples had a range and average concentration of diazinon of 0.01-0.10 ppb and 0.04 ppb, respectively(4). The concentration of diazinon in the Beaver River (Beaver Falls, PA) was 0.09 ppb(5). In Ontario, Canada between 1975 to 1977, 0.1% samples collected from 11 agricultural watersheds had a range, maximum, and average concentration of diazinon of not detected-0.15 parts per trillion,<0.01 parts per trillion, and average <0.01 parts per trillion, respectively(6). Diazinon was not detected (detection limit = 1 ppb) in a 1985-1987 study of drainage ditch water on farms in British Columbia, Canada in an area where the pesticide is known to be used even though the pesticide was sporadically found in the sediments of the ditches(7). Between 1983 to 1987, the highest concentration of diazinon in Sacramento-San Joaquin Delta water was 0.1 ug/L(8). Diazinon was detected in surface water samples collected from Tablelands (at Sequoia National Park) and Sixty Lakes Basin (Kings Canyon National Park) CA between Aug 18-22, 1997 at respective concentrations of 3.1-3.4 and 1.8 ng/L(9). Diazinon was detected in 19 of 30 lake water samples collected from Canada and the northeastern US between July 1998 and Sept 2001 at concentrations ranging from <0.003 to 9.7 ng/L(10); mean concentrations were 2.8 ng/L (agricultural input lakes), 2.8 ng/L (remote mid-latitude lakes), 2.8 ng/L (sub-arctic lakes) and 0.72 ng/L (arctic lakes)(10). Diazinon was detected (detection limit 0.005 ug/L) in 71% of water samples collected from the Kisco River (southeastern NY) between May 2000 and Feb 2001 at maximum concentration of 0.24 ug/L(11). Diazinon was detected in 5% (detection limit 0.5 ug/L) of samples collected from 18 sites on 7 streams in Arkansas between Mar and Aug 2004(12). Diazinon was detected in 25.9% of 85 stream water samples collected between 1999 and 2000 at sites in 30 States in the US at a median concentration of 0.07 ug/L(13).
(1) USEPA; Envirofacts. National Contaminant Occurrence Database (NCOD) on Diazinon. Available from, as of Sept 13, 2000: https://www.epa.gov:9966/ncod/rpt_options_pws_pkg.national_state_selection
(2) USEPA; Health and Environ Effects Profile for Diazinon Final Draft ECAO-CIN-P074 (1984)
(3) Carey AE, Kutz FW; Environ Monit Assess 5: 155-63 (1985)
(4) Schulze JA et al; Pestic Monit 7: 73-84 (1973)
(5) Ohio Valley Water Sanitation Commission; Ohio River Main Stem Assessment of 1977 and Future Water Quality Conditions Cincinnati, OH (1978)
(6) Frank R et al; J Environ Qual 11: 497-505 (1982)
(7) Wan MT; J Environ Sci Health B24: 183-203 (1989)
(8) Lam RHF et al; pp. 15-44 in Water Contamination and Health, Wang RGM, ed. NY, NY: Marcel Dekker, Inc (1994)
(9) Fellers GM et al; Environ Toxicol Chem 23: 2170-2177 (2004)
(10) Muir DCG et al; Environ Toxicol Chem 23: 2421-2432 (2004)
(11) Phillips PJ, Bode RW; Pest Manag Sci 60: 531-543 (2004)
(12) Haggard BE et al; J Environ Qual 35: 1078- 1087 (2006)
(13) Kolpin DW et al; Environ Sci Technol 36: 1202-11 (2002)
RAIN/SNOW/FOG: The annual mean concentration of diazinon in precipitation (rain/snow) was 0.011 ug/L measured in Niigata City, Japan between April 1992 and March 1993(1); the highest concentration of diazinon (0.17 ug/L) was measured in August 1992(1). During the period between 1995-6, the diazinon concentration in rain and snow from the Sierra Nevada mountains ranged from <0.057 to 19 ng/L(2). Fogwater collected from agricultural areas (Lodi, CA; Beltsville, MD; Monterey, CA; Parlier, PA) contained 22, 0.14, 3.6, 4.8, and 16.6 ug/L of diazinon, respectively(3). Diazinon was detected in 17% of 205 rain water samples collected from an agricultural area in Greece between June 1997 and June 1998 at a mean concentration of 0.07 ug/L(4). Diazinon was detected in 20% of rainwater samples (1.96 ng/L detection limit) collected during the agricultural seasons of 2000-2003 at the Delmarva Peninsula(4); average concentrations (in ng/L) for each of four seasons were 0.4, 0.5, 6.2 and 18 ng/L respectively(4).
(1) Kawata K et al; Bull Environ Contam Toxicol 57: 853-58 (1996)
(2) McConnell LL et al; Environ Toxicol Chem 17: 1908-16 (1998)
(3) Rice CP; Pesticide Outlook 7: 31-6 (1996)
(4) Charizopoulos E, Mourkidou E; Environ Sci Tech 33: 2363-68 (1999)
(5) Goel A et al; J Agric Food Chem 53: 7915-7924 (2005)

6.11 Effluent Concentrations (Complete)

Diazinon was detected in the effluent of 1 of 10 wastewater treatment plants(1). Storm water runoff samples (128 total samples collected from 8 land use areas in California in 2001) had 93% positive detection of diazinon(2); concentrations at two areas ranged from 227 to 505 ng/L(2).
(1) Ellis DD et al; Arch Environ Contam Toxicol 11: 373-82 (1982)
(2) Schiff K, Sutula M; Environ Toxicol Chem 23: 1815-1821 (2004)

6.12 Sediment / Soil Concentrations (Complete)

SEDIMENT: Between 1976 to 1980, diazinon was detected in 0.5% of sediment samples from the National surface water monitoring program, with a max concentration of 7.1 ppb(1). Diazinon was detected in the Scioto River (Highby, OH) at a concentration of 0.07 ppb(2). The concentration of diazinon in San Joaquin River sediment (in 1992) was <0.5 ng/L(3).
(1) Carey AE, Kutz FW; Environ Monit Assess 5: 155-63 (1985)
(2) Ohio Valley Water Sanitation Commission; Ohio River Main Stem Assessment of 1977 and Future Water Quality Conditions Cincinnati, OH (1978)
(3) Pereira WE et al; Environ Toxicol Chem 15: 172-80 (1996)
SOIL: As part of the US National Soils Monitoring Program in 1972, the concentration of diazinon, in 5.4% soil samples collected from 1,483 sites in 37 states, ranged from 0.07-0.17 ppm (dry wt) and averaged <0.01 ppm(1). In 1972, diazinon was detected in soil from rice-growing areas of Texas(2); 7.8% of 99 samples had detectable levels of diazinon(2); and 28% of 25 samples had a range and average diazinon concentration of 0.01-0.06 ppm (dry wt) and 0.01 ppm, respectively(2). Diazinon was detected in 28% of 46 soil samples, with a maximum concentration of <0.1 ppm, in 5 counties located in western Alabama(3). Diazinon was detected in 46% of soil samples taken from 28 farms in vegetable growing areas of Southwestern Ontario (Canada), with a range and average concentration of trace-0.29 ppm and 8.9 ppm, respectively(4). Diazinon was sporadically found at concentration up to 4.0 ug/kg in sediments in drainage ditches on farms in British Columbia in a study done between (1985 and 1987)(5). The average and range of diazinon at agrichemical facilities in Illinois was 75 ug/kg and 2.3-17,000 ug/kg, respectively(6).
(1) Carey AE et al; Pestic Monit J; 12: 209-29 (1979)
(2) Carey AE et al; Pestic Monit J; 14: 23-5 (1980)
(3) Albright R et al; Bull Environ Contam Toxicol 12: 378-84 (1974)
(4) Miles JRW, Harris CR; J Environ Health B13: 199-209 (1978)
(5) Wan MT; J Environ Sci Health B24: 183-203 (1989)
(6) Krapac IG et al; J Soil Contam 4: 209-226 (1995)

6.13 Atmospheric Concentrations (Complete)

Diazinon was measured in ambient air as part of a US National Monitoring Program(1); in 1970, the maximum and average concentration of diazinon in 61% of 787 samples taken in 14 states was 62.2 and 3.0 ng/cu m, respectively(1); in 1971, the maximum and average concentration of diazinon in 41% of 667 samples taken in 16 states was 27.9 and 2.0 ng/cu m, respectively(1). The concentration of diazinon was measured in ambient air at 10 locations in US in the year 1980(2); 48% of 123 samples had a maximum and average concentration of diazinon of 23 and 2.1 ng/cu m, respectively; in Pekin, IL between Feb-March, 1980, the range and average concentration of diazinon in 73% of 11 samples was 1.4-10 and 3.3 ng/cu m, respectively(2).
(1) Kutz FW et al; pp. 95-136 in Air Pollut From Pest Agric Processes. Lee RE Jr, ed. Cleveland, OH: CRC Press (1976)
(2) Carey AE, Kutz FW; Environ Monit Assess 5: 155-63 (1985)
URBAN/SUBURBAN: As part of the National Human Exposure Assessment Survey (NHEXAS) in Arizona, the median concentration of diazinon in outdoor air was <2.1 ng/cu m(1). In Jacksonville FL and Springfield MA, the median concentration (ng/cu m) of diazinon in outdoor air was <30 (summer; winter, <15) and <22 (spring; winter, <28), respectively(1). The estimated mean air concentration of diazinon in outdoor air for Springfield/Chicopee, MA in the spring 1987 and winter 1988 was 8.2 and 9.2 ng/cu m, respectively(2). The concentration of diazinon in ambient air near Kitakyushu City, Japan in 1992 was 0.05 ng/cu m(3). Based on measured outdoor air concentrations between 1986 and 2000 in California, the mean urban community air concentration of diazinon is reported to be 0.011 ug/cu m(4).
(1) Gordon SM et al; J Exp Analysis Environ Epid 9: 456-470 (1999)
(2) Whitmore RW et al; Arch Environ Contam Toxicol 26: 47-59 (1994)
(3) Haraguchi K et al; Atmos Environ 28: 1319-25 (1994)
(4) Lee S et al; Environ Health Perspect 110: 1175-1184 (2002)
INDOOR AIR: As part of the National Human Exposure Assessment Survey (NHEXAS) in Arizona, the median concentration of diazinon in indoor air was 4.6 ng/cu m(1). In Jacksonville FL, Springfield MA, and Brownsville TX, the median concentration (ng/cu m) of diazinon in indoor air was 73 (summer; winter, 21), <22(spring; winter, <28), and 3.5 (summer; spring, 1.4), respectively(1). As part of NHEXAS in Arizona, the median concentration of diazinon in house dust was 0.13 ng/cu m(1). In Jacksonville, FL and Brownsville, TX, the median concentrations (ng/cu m) of diazinon in house dust were 0.4 (winter) and 0.07 (summer; spring,<22), respectively(1). Between mid-September and mid-November 1991, diazinon was detected in household dust (in New Jersey) at a concentration of 90 ng/g(2). Diazinon was detected 100% of 52 semipermeable membranes devices (SPMD) deployed in 52 homes situated along the border between Arizona and Mexico at an average concentrations of 4200 ug per 4 SPDM(3).
(1) Gordon SM et al; J Exp Analysis Environ Epid 9: 456-470 (1999)
(2) Roinestad KS et al; J AOAC Inter 76: 1121-6 (1993)
(3) Gale RW et al; Environ Sci Technol 43: 3954-3060 (2009)
RURAL/REMOTE: The maximum and median concentration, and percent detections of diazinon in air over the Mississippi River from New Orleans, LA to St. Paul, MN during June 1994 was 0.36 ng/cu m, 0.08 ng/cu m, and 100%, respectively(1). Based on measured outdoor air concentrations between 1986 and 2000 in California, the mean rural community air concentration of diazinon is reported to be 0.025 ug/cu m(2).
(1) Majewski MS et al; Environ Sci Technol 32: 3689-98 (1998)
(2) Lee S et al; Environ Health Perspect 110: 1175-1184 (2002)
SOURCE DOMINATED: Concentrations of diazinon in air samples within 800 m of two formulation plants in Arkansas were as follows: 1970, ng/cu m, 66 samples, 62% positive, 0.3-9.2, average 1.8; 1971, 60 samples, 48% positive, 0.3-5.8, average 1.5; 1972, 64 samples, 44% positive, 0.5-18, average 3.2(1). Concentrations in air samples 275 m from a formulation plant in Tennessee sampled in 1971 were as follows: 56 samples, 66% positive, 0.5-27.9 ng/cu m, average 7.3 ng/cu m(1). Air samples from a retail garden store contained 3.4 ug diazinon/cu m(2).
(1) Lewis RG, Lee RE Jr; pp. 5-51 in Air Pollut From Pest Agric Processes. Lee RE Jr, ed. Cleveland, OH: CRC Press (1976)
(2) Wachs T et al; Bull Environ Contam Toxicol 31: 582-4 (1983)

6.14 Food Survey Values (Complete)

As part of US Market basket surveys for Fiscal Year 1999(1), the mean level of diazinon residues found in food (in ppm) was reported as follows: beef steak, pan-cooked (0.0009); pork chop, pan-cooked (0.0008); lamb chop, pan-cooked (0.0055); hamburger, fast-food (0.0005); lasagna with meat (0.003); chicken potpie, frozen (0.0005); chicken nuggets, fast-food (0.001); chicken, fried fast-food (0.002); beef stroganoff (0.0018); tuna noodle casserole (0.0026); turkey, frozen meal (0.0007); cheeseburger, fast-food (0.0009); fish sandwich, fast-food (0.0013); frankfurter, fast-food (0.0007); egg/cheese/ham, fast-food (0.0005); taco or tostada, carry-out (0.0008); pepperoni pizza, carry-out (0.0023); beef chow mein, carry-out (0.0023); brown gravy, homemade (0.002); split peas with veg, ham (0.0002)(1).
(1) USFDA; Total Diet Study, Summary of Residues Found Ordered by Pesticide, Market Baskets 91-3-97-1 (June, 1999). Washington, DC: US Food and Drug Administration. Available from, as of Sept 13, 2000: https://vm.cfsan.fda.gov/~acrobat/TDS1byps.pdf
As part of US Market basket surveys for Fiscal Year 1999(1), the mean level of diazinon residues found in food (in ppm) was reported as follows: green peas, boiled (0.002); corn, boiled (0.0007); apple, red, raw (0.0012); peach, raw (0.003); pear, raw (0.001); strawberries, raw (0.0035); plums, raw (0.002); grapefruit (0.006); sweet cherries, raw (0.003); raisins, dried (0.0004); spinach, boiled (0.0013); collards, boiled (0.001); coleslaw with dressing (0.001); broccoli, boiled (0.0015); celery, raw (0.0339); cauliflower, boiled (0.01); green beans, boiled (0.001); green pepper, raw (0.026); winter squash, baked (0.0007); applesauce, strained/junior (0.003); pumpkin pie (0.001); peas, mature, dry, boiled (0.014); mixed nuts without peanuts (0.001); apricot, raw (0.0017); French fries, fast-food (0.0017); carrot, fresh, boiled (0.01); Brussel sprouts, boiled (0.0044); mushrooms, raw (0.0056); green peppers, stuffed (0.002); mushroom soup, canned (0.002)(1).
(1) USFDA; Total Diet Study, Summary of Residues Found Ordered by Pesticide, Market Baskets 91-3-97-1 (June, 1999). Washington, DC: US Food and Drug Administration. Available from, as of Sept 13, 2000: https://vm.cfsan.fda.gov/~acrobat/TDS1byps.pdf
As part of US Market basket surveys for Fiscal Year 1999(1), the mean level of diazinon residues found in food (in ppm) was reported as follows: popcorn, popped in oil (0.008); white bread (0.0025); white roll (0.002); cornbread, homemade(0.0007); biscuit, baked (0.0016); whole wheat bread (0.003); rye bread (0.003); blueberry muffin (0.004); saltine crackers (0.005); pancake from mix (0.003); egg noodles, boiled (0.001); fruit-flavored cereal (0.001); shredded wheat cereal(0.001); granola cereal (0.0011); sweet roll or Danish (0.003); chocolate chip cookies (0.004); cracked wheat bread (0.0025); bagel, plain (0.001); English muffin, toasted (0.009); graham crackers (0.001); butter-type crackers (0.006); cheese pizza, carry-out (0.0017); chocolate snack cake (0.0025); cake doughnuts with icing (0.003); brownies, commercial (0.0022); sugar cookies, commercial (0.004); teething biscuits (0.001)(1)..
(1) USFDA; Total Diet Study, Summary of Residues Found Ordered by Pesticide, Market Baskets 91-3-97-1 (June, 1999). Washington, DC: US Food and Drug Administration. Available from, as of Sept 13, 2000: https://vm.cfsan.fda.gov/~acrobat/TDS1byps.pdf
As part of the USFDA Total Diet Study in 1991, the maximum concentration of diazinon residues in domestic and imported apples was 0.02 and 0.8 ppm, respectively(1). Diazinon was detected in 6 of 153 produce samples (fruits and vegetables) collected in Santa Monica CA between Sept 2002 and Oct 2004 (quantification values or detection limits not reported). Diazinon concentrations of 2.1 to 5.5 ug/kg were detected in commercial fruit juices (apple, grape, orange and pineapple) collected from supermarkets in Madrid Spain(3).
(1) Roy RR et al; J AOAC Inter 80: 883-94 (1997)
(2) Zhang X et al; J Agric Food Chem 56: 10638-10645 (2008)
(3) Albero B et al; J Agric Food Chem 51: 6915-6921 (2003)

6.15 Fish / Seafood Concentrations (Complete)

As part of the US Market basket surveys for 1969-76, the mean level of diazinon found in fish/seafood was measured as follows(1): fish, domestic (0.0008 ppm, 1.1% of 2901 samples); fish imported (1% of 361 samples, 0.0001 ppm); shellfish, domestic (0.8% of 291 samples, 0.0001 ppm); shellfish, imported (1.4% of 152 samples, 0.0002 ppm).
(1) Duggan RE et al; Pest Res Levels in Foods in the United States From July 1, 1969 to June 30, 1976; Washington, DC FDA Div Chem Technol (1983)

6.16 Milk Concentrations (Complete)

As part of the US Market basket surveys for 1969-76, the mean level of diazinon found in milk was measured as follows(1): fluid milk, domestic (0.2% of 4638 samples, <0.0001 ppm). As part of the USFDA Total Diet Study during fiscal years 1985-91, the maximum concentration of diazinon residue in milk was 0.17 ppm(1).
(1) Duggan RE et al; Pest Res Levels in Foods in the United States From July 1, 1969 to June 30, 1976; Washington, DC FDA Div Chem Technol (1983)
Two lactating goats were orally treated with (pyrimidine-14C)-diazinon (specific activity 9.7 uCi/mg) in gelatin capsules for four consecutive days at a dose level of 4.5 mg/kg per day, corresponding to a dietary exposure of 100 mg/kg of feed. During the observation period, an average 64.1% of the administered radioactivity was excreted with urine, 10.4% with the feces and 0.31% with the milk. A plateau of radioactivity in the milk was reached after 3 days of dosing at a mean level of 0.46 mg/kg diazinon equivalent.
WHO; Environ Health Criteria 198: Diazinon (333-41-5) (1998); Available from, as of August 31, 2011: https://www.inchem.org/pages/ehc.html

6.17 Other Environmental Concentrations (Complete)

Diazinon concentrations of 1.0 to 19.6 ug/sq m were detected in surface dust wipe samples collected in house dust residues from 10 farmers homes in central NY in 1999(1); diazinon concentrations in carpet dust samples ranged from 0.1 to 27.4 ug/sq(1). Diazinon was detected in 20 of 26 house dust samples collected from farmer worker houses in Oregon in 1999 at a mean concentration 0.31 ug/g(2). Diazinon was detected in 35% of 480 hard surface floor wipe samples collected in US homes between June 2005 and March 2006 as part of a survey conducted by the Dept of Housing and Urban Development and USEPA at a mean concentration of 0.03 ng/sq cm(3). Diazinon was detected in 60% of 80 floor wipe samples collected in US child care centers between July 2001 and Oct 2001 as part of a survey conducted by the Dept of Housing and Urban Development and USEPA at a mean concentration of 0.11 ng/sq cm(4).
(1) Lemley AT et al; Bull Environ Contam Toxicol 69: 155-163 (2002)
(2) Rothlein J et al; Environ Health Perspect 114: 691-696 (2006)
(3) Stout DM et al; Environ Sci Technol 43: 4294-4300 (2009)
(4) Tulve NS et al; Environ Sci Technol 40: 6269-6274 (2006)

7 Environmental Standards & Regulations

7.1 Allowable Tolerances (Complete)

Tolerances are established for residues of the insecticide diazinon O,O-diethyl O-(6-methyl-2-(1-methylethyl)-4-pyrimidinyl)phosphorothioate in or on the following food commodities:
Commodity
Almond, hulls
Parts per million
3.0
Commodity
Apple
Parts per million
0.50
Commodity
Apricot
Parts per million
0.20
Commodity
Bean, lima
Parts per million
0.50
Commodity
Bean, snap, succulent
Parts per million
0.50
Commodity
Beet, garden, roots
Parts per million
0.75
Commodity
Beet, garden, tops
Parts per million
0.70
Commodity
Blueberry
Parts per million
0.50
Commodity
Caneberry subgroup 13-07A
Parts per million
0.75
Commodity
Carrot, roots
Parts per million
0.75
Commodity
Cattle, fat
Parts per million
0.50
Commodity
Cherry, sweet
Parts per million
0.20
Commodity
Cherry, tart
Parts per million
0.20
Commodity
Cranberry
Parts per million
0.50
Commodity
Endive
Parts per million
0.70
Commodity
Fig
Parts per million
0.50
Commodity
Ginseng
Parts per million
0.75
Commodity
Grape
Parts per million
0.75 (The expiration/revocation date for this tolerance is 9/10/2010)
Commodity
Hazelnut
Parts per million
0.50
Commodity
Kiwifruit (There are no domestic registrations for kiwifruit as of March 6, 2002)
Parts per million
0.75
Commodity
Lettuce
Parts per million
0.70
Commodity
Melon
Parts per million
0.75
Commodity
Mushroom
Parts per million
0.75 (The expiration/revocation date for this tolerance is 9/10/2010)
Commodity
Nectarine
Parts per million
0.20
Commodity
Onion, bulb
Parts per million
0.75
Commodity
Onion, green
Parts per million
0.75
Commodity
Pea, succulent
Parts per million
0.50
Commodity
Peach
Parts per million
0.20
Commodity
Pear
Parts per million
0.50
Commodity
Pineapple
Parts per million
0.50
Commodity
Plum, prune, fresh
Parts per million
0.20
Commodity
Radish
Parts per million
0.50
Commodity
Rutabaga
Parts per million
0.75
Commodity
Spinach
Parts per million
0.70
Commodity
Strawberry
Parts per million
0.50
Commodity
Tomato
Parts per million
0.75
Commodity
Vegetable, brassica, leafy, group 5
Parts per million
0.70
Commodity
Watercress
Parts per million
0.05
40 CFR 180.153(a) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of August 29, 2011: https://www.ecfr.gov
Tolerances with regional registrations, as defined in part 180.1(l), are established for residues of the insecticide diazinon O,O-diethyl O-(6-methyl-2-(1-methylethyl)-4-pyrimidinyl)phosphorothioate in or on the following food commodities:
Commodity
Almond
Parts per million
0.50
Commodity
Banana
Parts per million
0.20
Commodity
Celery
Parts per million
0.70
Commodity
Cucumber
Parts per million
0.75
Commodity
Parsley, leaves
Parts per million
0.75
Commodity
Parsnip
Parts per million
0.50
Commodity
Pepper
Parts per million
0.5
Commodity
Potato
Parts per million
0.10
Commodity
Squash, summer
Parts per million
0.50
Commodity
Squash, winter
Parts per million
0.75
Commodity
Sweet potato, roots
Parts per million
0.10
Commodity
Swiss chard
Parts per million
0.70
Commodity
Turnip, roots
Parts per million
0.50
Commodity
Turnip, tops
Parts per million
0.75
40 CFR 180.153(c) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of August 29, 2011: https://www.ecfr.gov

7.2 CERCLA Reportable Quantities (Complete)

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 1 lb or 0.454 kg. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).
40 CFR 302.4 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of August 30, 2011: https://www.ecfr.gov

7.3 State Drinking Water Guidelines (Complete)

(AZ) ARIZONA 0.63 ug/l
USEPA/Office of Water; Federal-State Toxicology and Risk Analysis Committee (FSTRAC). Summary of State and Federal Drinking Water Standards and Guidelines (11/93) To Present
(CA) CALIFORNIA 6 ug/l
USEPA/Office of Water; Federal-State Toxicology and Risk Analysis Committee (FSTRAC). Summary of State and Federal Drinking Water Standards and Guidelines (11/93) To Present
(FL) FLORIDA 6.3 ug/l
USEPA/Office of Water; Federal-State Toxicology and Risk Analysis Committee (FSTRAC). Summary of State and Federal Drinking Water Standards and Guidelines (11/93) To Present

8 Chemical / Physical Properties

8.1 Molecular Formula

C12-H21-N2-O3-P-S

8.2 Molecular Weight

304.35
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509

8.3 Color / Form (Complete)

Colorless oil
Mester, R.T.,Sine, C. (eds.) Crop Protection Handbook Volume 97. Meisterpro. Willoughby,OH. 2011, p. 349
Clear, colorless liquid
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)

8.4 Odor

Faint ester-like odor
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509

8.5 Boiling Point

BP: 125 °C at 1 mm Hg
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)

8.6 Density

Specific gravity: 1.116-1.118 at 20 °C/4 °C
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509

8.7 LogP

log Kow = 3.81
Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 106

8.8 Dissociation Constants

pKa = 2.6
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)

8.9 Solubility (Complete)

Completely miscible with common organic solvents, e.g. ethers, alcohols, benzene, toluene, hexane, cyclohexane, dichloromethane, acetone, petroleum oils.
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
Freely soluble in ketones
Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 389
Solubility in water: 0.004% at 20 °C
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509
Solubility in water: 60 mg/L at 20 °C
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
In water, 40 mg/L at 25 °C
Sharom MS et al; Water Res 14: 1095-100 (1980)

8.10 Vapor Pressure

9.01X10-5 mm Hg at 25 °C
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)

8.11 Refractive Index

Index of refraction: 1.4978-1.4981 at 20 °C/D
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509

8.12 Other Experimental Properties (Complete)

Hydrolysis of diazinon and diazoxon conform to pseudo first-order rate in pH range 3.1-10.9.
Menzie, C.M. Metabolism of Pesticides. U.S. Department of the Interior, Bureau of Sport Fisheries and Wildlife, Publication 127. Washington, DC: U.S. Government Printing Office, 1969., p. 144
log Kow = 3.30 (OECD method 107)
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
Volatility: at 20 °C = 2.4 mg/cu m; at 40 °C = 17.6 mg/cu m
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509
Incompatible with copper-containing compounds
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)
Pale-to-dark brown liquid (at least 90% pure) /Technical/
Mester, R.T.,Sine, C. (eds.) Crop Protection Handbook Volume 97. Meisterpro. Willoughby,OH. 2011, p. 349
Yellow liquid /Technical/
MacBean C, ed; e-Pesticide Manual. 15th ed., ver. 5.1, Alton, UK; British Crop Protection Council. Diazinon (CAS 333-41-5) (2008-2010)

9 Spectral Information

9.1 Mass Spectrometry

9.1.1 Other MS

Other MS
MASS: 23854 (NIST/EPA/MSDC Mass Spectral Database, 1990 version): 4788 (National Bureau of Standards)

9.2 Other Spectra

Intense mass spectral peaks: 179 m/z (100%), 137 m/z (94%), 152 m/z (85%), 304 m/z (64%)
Hites, R.A. Handbook of Mass Spectra of Environmental Contaminants. Boca Raton, FL: CRC Press Inc., 1985., p. 310

10 Chemical Safety & Handling

10.1 DOT Emergency Guidelines (Complete)

/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Health: TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Inhalation or contact with some of these materials will irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion and poison hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Public Safety: CALL Emergency Response Telephone Number ... As an immediate precautionary measure, isolate spill or leak area for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate closed spaces before entering. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer. It may provide little or no thermal protection. Structural firefighters' protective clothing provides limited protection in fire situations ONLY; it is not effective in spill situations where direct contact with the substance is possible. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Evacuation: ... Fire: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Fire: CAUTION: All these products have a very low flash point. Use of water spray when fighting fire may be inefficient. Small fires: Dry chemical, CO2, water spray or alcohol-resistant foam. Large fires: Water spray, fog or alcohol-resistant foam. Move containers from fire area if you can do it without risk. Dike fire control water for later disposal; do not scatter the material. Use water spray or fog; do not use straight streams. Fire involving tanks or car/trailer loads: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ Spill or Leak: Fully encapsulating, vapor protective clothing should be worn for spills and leaks with no fire. ELIMINATE all ignition sources (no smoking, flares, sparks or flames in immediate area). All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. A vapor suppressing foam may be used to reduce vapors. Small spills: Absorb with earth, sand or other non-combustible material and transfer to containers for later disposal. Use clean non-sparking tools to collect absorbed material. Large spills: Dike far ahead of liquid spill for later disposal. Water spray may reduce vapor; but may not prevent ignition in closed spaces. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 131: FLAMMABLE LIQUIDS-TOXIC/ First Aid: Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. Wash skin with soap and water. Keep victim warm and quiet. In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin. Effects of exposure (inhalation, ingestion or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. /Organophosphorus pesticide, liquid, flammable, poisonous; Organophosphorus pesticide, liquid, flammable, toxic; Organophosphorus pesticide, liquid, poisonous, flammable; Organophosphorus pesticide, liquid, toxic, flammable/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Health: Highly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Fire or Explosion: Combustible material: may burn but does not ignite readily. Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Public Safety: CALL Emergency Response Telephone Number ... As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer. It may provide little or no thermal protection. Structural firefighters' protective clothing provides limited protection in fire situations ONLY; it is not effective in spill situations where direct contact with the substance is possible. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Evacuation: ... Fire: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Fire: Small fires: Dry chemical, CO2 or water spray. Large fires: Water spray, fog or regular foam. Move containers from fire area if you can do it without risk. Dike fire control water for later disposal; do not scatter the material. Use water spray; do not use straight streams. Fire involving tanks or car/trailer loads: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Spill or Leak: ELIMINATE all ignition sources (no smoking, flares, sparks or flames in immediate area). Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. Cover with plastic sheet to prevent spreading . Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. DO NOT GET WATER INSIDE CONTAINERS. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008
/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ First Aid: Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin. Keep victim warm and quiet. Effects of exposure (inhalation, ingestion or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. /Organophosphorus pesticide, liquid, poisonous; Organophosphorus pesticide, liquid, toxic; Organophosphorus pesticide, solid, poisonous; Organophosphorus pesticide, solid, toxic/
U.S. Department of Transportation. 2008 Emergency Response Guidebook. Washington, D.C. 2008

10.2 Fire Potential

PRACTICALLY NONFLAMMABLE.
Clayton, G. D. and F. E. Clayton (eds.). Patty's Industrial Hygiene and Toxicology: Volume 2A, 2B, 2C: Toxicology. 3rd ed. New York: John Wiley Sons, 1981-1982., p. 4815

10.3 Autoignition Temperature

> 400 °C. /Diazinon 50W/
Makhteshim Agan of North America, Inc; MSDS for Diazinon 50W (Date: 10-8-08). Available from, as of November 17, 2011: https://www.cdms.net/LDat/mp5RD002.pdf

10.4 Fire Fighting Procedures (Complete)

Fire Extinguishing Media: dry chemical, foam, carbon dioxide.
Mester, R.T.,Sine, C. (eds.) Crop Protection Handbook Volume 97. Meisterpro. Willoughby,OH. 2011, p. 349
If material is on fire or involved in fire: Do not extinguish fire unless flow can be stopped. Use water in flooding quantities as fog. Solid streams of water maybe ineffective. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Use "alcohol foam, dry chemical, or carbon dioxide. /Organophosphorous Pesticides, liquid, toxic/
Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 678
In Case of Fire: Use dry chemical, foam, or CO2 extinguishing media. Wear full protective clothing and self-contained breathing apparatus. Evacuate nonessential personnel from the area to prevent human exposure to fire, smoke, fumes, or products of combustion. Prevent use of contaminated building, area, and equipment until decontaminated. /Diazinon 50W/
Makhteshim Agan of North America, Inc; MSDS for Diazinon 50W (Date: 10-8-08). Available from, as of November 17, 2011: https://www.cdms.net/LDat/mp5RD002.pdf

10.5 Firefighting Hazards (Complete)

... Vapors are heavier than air and will collect in low areas. Containers may explode in fire. ...
Sittig, M. Handbook of Toxic and Hazardous Chemicals and Carcinogens, 2002. 4th ed.Vol 1 A-H Norwich, NY: Noyes Publications, 2002., p. 772

10.6 Hazardous Reactivities and Incompatibilities (Complete)

Strong acids and alkalis, copper containing compounds [Note: Hydrolyzes slowly in water and dilute acid].
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)

10.7 Personal Protective Equipment (PPE) (Complete)

Personnel protection: Wear positive pressure self-contained breathing apparatus. Wear appropriate chemical protective clothing. /Organophosphorous Pesticides, liquid, toxic/
Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 678
Wear appropriate personal protective clothing to prevent skin contact.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Wear appropriate eye protection to prevent eye contact.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Eyewash fountains should be provided in areas where there is any possibility that workers could be exposed to the substance; this is irrespective of the recommendation involving the wearing of eye protection.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.]
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)

10.8 Preventive Measures (Complete)

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.
Use this product only in accordance with its labeling and with the Worker Protection Standard, 40 CFR Part 170. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Personal Protective Equipment (PPE). ... Mixers, loaders, applicator and other handlers using engineering controls must wear: long-sleeved shirt and long pants; shoes plus socks; chemical-resistant gloves if mixing or loading; chemical-resistant apron if mixing or loading. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Follow manufacturer's instructions for cleaning/maintaining PPE (personal protective equipment). If no such instructions for washables exist, use detergent and hot water. Keep and wash PPE separately from other laundry. Discard clothing and other absorbent materials that have been drenched or heavily contaminated with this product's concentrate. Do not reuse them. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Users should: Wash hands before eating, drinking, chewing gum, using tobacco, or using the toilet; Remove clothing/PPE immediately if pesticide gets inside. Then wash thoroughly and put on clean clothing.; Remove PPE immediately after handling this product. Wash the outside of gloves before removing. As soon as possible, wash thoroughly and change into clean clothing. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Do not enter or allow worker entry into treated areas during the restricted-entry interval. ... PPE required for early entry to treated areas that is permitted under the Worker Protection Standard and that involves contact with anything that has been treated such as plants, soil, or water is: Coverall worn over long-sleeved shirt and long pants; chemical-resistant gloves made of any waterproof material; chemical-resistant footwear plus socks; and chemical-resistant headgear if overhead exposures. Notify workers of the application by warning them orally and by posting warning signs at entrances to treated areas. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
The worker should immediately wash the skin when it becomes contaminated.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Work clothing that becomes wet or significantly contaminated should be removed or replaced.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premises.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
If material not on fire and not involved in fire: Keep sparks, flames, and other source of ignition away. Keep material out of water sources and sewers. Build dikes to contain flow as necessary. Attempt to stop leak if without undue personnel hazard. Use water spray to knock down vapors. /Organophosphorous Pesticides, liquid, toxic/
Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 678
Personnel protection: Avoid breathing vapors. Keep upwind. ... Avoid bodily contact with the material. ... Do not handle broken packages unless wearing appropriate personal protective equipment. Wash away any material which may have contacted the body with copious amounts of water or soap and water. /Organophosphorous Pesticides, liquid, toxic/
Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 678
SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. The completeness of the cleaning procedures should be considered before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at the end of shift, but should remain at employee's place of work for cleaning.

10.9 Stability / Shelf Life (Complete)

More stable in alkaline formulations, then when at neutral or acid pH.
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 509
SHELF-LIFE OF AT LEAST 3 TO 5 YR WHEN STORED IN A DRY PLACE & MINIMUM STORAGE TEMP.
Farm Chemicals Handbook 1983. Willoughby, Ohio: Meister Publishing Co., 1983., p. C-75
SENSITIVE TO OXIDN ABOVE 100 °C; DEGRADATION ABOVE 120 °C
Sunshine, I. (ed.). CRC Handbook of Analytical Toxicology. Cleveland: The Chemical Rubber Co., 1969., p. 509

10.10 Shipment Methods and Regulations (Complete)

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./
49 CFR 171.2; U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of November 22, 2011: https://www.ecfr.gov
The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.
International Air Transport Association. Dangerous Goods Regulations. 47th Edition. Montreal, Quebec Canada. 2006., p. 231
The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.
International Maritime Organization. International Maritime Dangerous Goods Code. London, UK. 2004., p. 149, 134

10.11 Storage Conditions (Complete)

Store in original container only in cool, dry, well-ventilated, secure area out of reach of children and animals.
Mester, R.T.,Sine, C. (eds.) Crop Protection Handbook Volume 97. Meisterpro. Willoughby,OH. 2011, p. 349

10.12 Cleanup Methods (Complete)

In case of spill or leak: For small spills, sweep up keeping dust to a minimum, and place in a approved chemical container. Wash the spill area with water containing a strong detergent, absorb with pet litter or other absorbent material, sweep up, and place in a chemical container. Seal the container and handle in an approved manner. Flush the area with water to remove any residue. Do not allow wash water to contaminate water supplies. Wear appropriate PPE. /Diazinon 50W/
Makhteshim Agan of North America, Inc; MSDS for Diazinon 50W (Date: 10-8-08). Available from, as of November 17, 2011: https://www.cdms.net/LDat/mp5RD002.pdf
Personal Protective Equipment (PPE). ... Handlers performing tasks such as cleaning equipment or spill cleanup for which engineering controls are not feasible must wear: coveralls over long-sleeved shirt and long pants; chemical-resistant gloves; chemical-resistant footwear plus socks; chemical-resistant apron if exposed to the concentrate; a respirator with an organic vapor-removing cartridge with a prefilter approved for pesticides (MSHA/NIOSH approval number prefix TC-23C) or a canister approved for pesticides (MSHA/NIOSH approval number prefix TC-14G) or a NIOSH approved respirator with an organic vapor (OV) cartridge or canister with any R, P, or HE prefilter. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Environmental considerations: Land spill: Dig a pit, pond, lagoon, holding area to contain liquid or solid material. /SRP: If time permits, pits, ponds, lagoons, soak holes, or holding areas should be sealed with an impermeable flexible membrane liner./ Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash, cement powder, or commerical sorbents. /Organophosphorous Pesticides, liquid, toxic/
Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 678
Environmental considerations: Water spill: Use natural deep water barriers or oil spill control booms to limit spill travel. Remove trapped material with suction hoses. /Organophosphorous Pesticides, liquid, toxic/
Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 678
Environmental considerations: Air spill: Apply water spray or mist to knock down vapors. /Organophosphorous Pesticides, liquid, toxic/
Association of American Railroads; Bureau of Explosives. Emergency Handling of Hazardous Materials in Surface Transportation. Association of American Railroads, Pueblo, CO. 2005, p. 678

10.13 Disposal Methods (Complete)

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.
SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.
Pesticide Disposal: Pesticide wastes are toxic. Improper disposal is a violation of Federal law. To avoid harming aquatic organisms in rivers and other surface waters, do not pour spray mixture or rinse water into sanitary drains (for example; toilets, floor drains, and sinks) or into storm water sewers (for example; street drains). If pesticide, spray mixture, or rinsate cannot be disposed of by use according to the label instructions, contact your State Pesticide or Environmental Control Agency or the Hazardous Waste representative of the nearest EPA Regional Office for guidance. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Container Handling: Nonrefillable Container (flexible-bag-all weights): Nonrefillable container. Do not reuse or refill this container. Offer for recycling, if available. Once all water-soluble packets are used according to label instructions, dispose of empty outer bag in a sanitary landfill or by incineration, or, if allowed by State and local authorities, by burning. If burned, stay out of smoke.. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Container Handling: Nonrefillable Container (rigid-fifty pounds or less): Nonrefillable container. Do not reuse or refill this container. Offer for recycling, if available. Clean container promptly after emptying. Triple rinse as follows: Empty the remaining contents into application equipment or a mix tank. Fill the container 1/4 full with water and recap. Shake for 10 seconds. pour rinsate into application equipment or a mix tank or store rinsate for later use or disposal. Drain for 10 seconds after the flow begins to drip. Repeat this procedure two more times. /Diazinon 50W/
Makhteshim Agan of North America, Inc; Product Label for Diazinon 50W (EPA 042911/Rev F). Available from, as of November 17, 2011: https://www.cdms.net/LDat/ld5RD004.pdf
Hydrolysis: Diazinon is hydrolyzed in acid media. In excess water this cmpd yields diethylthiophosphoric acid and 2-isopropyl-4-methyl-6-hydroxypyrimidine. With insufficient water, highly toxic tetraethyl monothiopyrophosphate is formed.
United Nations. Treatment and Disposal Methods for Waste Chemicals (IRPTC File). Data Profile Series No. 5. Geneva, Switzerland: United Nations Environmental Programme, Dec. 1985., p. 250
Alkaline hydrolysis leads to complete degradation. The alkaline salt of diethylthiophosphoric acid and the 2-isopropyl-4-methyl-6-hydroxypyrimidine formed are considerably less toxic than diazinon. Acid hydrolysis: Complete degradation in large excess of water, same hydrolysis products are obtained as in alkaline hydrolysis. However, highly toxic tetraethyl dithio- and thiopyrophosphates have been found with insufficient water in acid medium. Oxidation leads to complete degradation but the diazoxon formed is equally toxic. For the decontamination of diazinon containers, the triple rinse and drain procedure developed by the National Agricultural Chemicals Association (NACA) is recommended. "Triple rinse" means the flushing of containers three times, each time using a volume of the normal diluent equal to approx 10% of the container's capacity and adding the rinse liquid to the spray mixture or disposing of it by a method prescribed for disposing of the pesticide. The use of a rinse soln containing caustic soda and detergent may also be considered. Recommendable methods: Hydrolysis & incineration. Peer-review: Large amt should be incinerated in a unit with effluent gas scrubbing. (Peer-review conclusions of an IRPTC expert consultation (May 1985))
United Nations. Treatment and Disposal Methods for Waste Chemicals (IRPTC File). Data Profile Series No. 5. Geneva, Switzerland: United Nations Environmental Programme, Dec. 1985., p. 251
The following wastewater treatment technologies have been investigated for diazinon: Concentration process: Biological treatment.
USEPA; Management of Hazardous Waste Leachate, EPA Contract No.68-03-2766 p.E-55 (1982)
The following wastewater treatment technologies have been investigated for diazinon: Concentration process: Reverse osmosis.
USEPA; Management of Hazardous Waste Leachate, EPA Contract No.68-03-2766 p.E-89 (1982)

11 Occupational Exposure Standards

11.1 OSHA Standards (Complete)

Vacated 1989 OSHA PEL TWA 0.1 mg/cu m, skin designation, is still enforced in some states.
NIOSH. NIOSH Pocket Guide to Chemical Hazards. DHHS (NIOSH) Publication No. 97-140. Washington, D.C. U.S. Government Printing Office, 1997., p. 362

11.2 Threshold Limit Values (TLV) (Complete)

8 hr Time Weighted Avg (TWA): 0.01 mg/cu m, skin, inhalable fraction and vapor.
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 23
Excursion Limit Recommendation: Excursions in worker exposure levels may exceed 3 times the TLV-TWA for no more than a total of 30 minutes during a work day, and under no circumstances should they exceed 5 times the TLV-TWA, provided that the TLV-TWA is not exceeded.
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 5
A4: Not classifiable as a human carcinogen.
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 23
Biological Exposure Index (BEI): Determinant: Cholinesterase activity in red blood cells; Sampling Time: discretionary ; BEI: 70% of individual's baseline. The determinant is nonspecific, since it is observed after exposure to other chemicals. /Acetylcholinesterase Inhibiting Pesticides/
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 100

11.3 NIOSH Recommendations (Complete)

Recommended Exposure Limit: 10 Hour Time-Weighted Average: 0.1 mg/cu m [skin].
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)

12 Manufacturing / Use Information

12.1 Uses (Complete)

For diazinon (USEPA/OPP Pesticide Code: 075801) ACTIVE products with label matches. /SRP: Registered for use in the U.S. but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses./
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of August 31, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Commercial agriculture products (excluding cattle ear tags) are restricted use due to avian and aquatic toxicity.
USEPA/OPPTS; Interim Reregistration Eligibility Decision (RED) on Diazinon (333-41-5). p.5 USEPA-738-R-04-006 (May 2004). Available from, as of November 20, 2011: https://www.epa.gov/pesticides/reregistration/status.htm
Diazinon is registered to control foliage and soil insects and pests of many fruit, nut, vegetable, and ornamental crops. Diazinon also is used in cattle eartags. All residential uses have been cancelled.
USEPA/OPPTS; Reregistration Eligibility Decisions (REDs) Database on Diazinon (333-41-5). USEPA-738-R-04-006. Available from, as of Sept 7, 2011: https://www.epa.gov/pesticides/reregistration/status.htm
Insecticide, nematicide, seed treatment/protectant
Mester, R.T.,Sine, C. (eds.) Crop Protection Handbook Volume 97. Meisterpro. Willoughby,OH. 2011, p. 349
MEDICATION (VET)

12.2 Manufacturers

Drexel Chemical Company, 1700 Channel Avenue, Memphis, TN 38106-1412,(901) 774-4370; Agricultural Division; Production site: Cordele, GA 31015
SRI Consulting, 2010 Directory of Chemical Producers. Menlo Park, CA. 2010, p. 757
Diazinon - Manufacturers (2009)
Company
Pty Ltd. (Formerly A &amp; C Chemicals)
Address
P.O. Box 596
City State Country
Burpengary, Qld. 4505, Australia
Company
Shenzhen Baocheng Chemical Industry Co., Ltd.
Address
A802, Tian An International Plaza, Renmin Nan Road
City State Country
Shenzhen 518005, China
Company
Rainbow Laboratories- a Huashu Pharmaceuticals Corp. JV Company
Address
2-602 Yin Zuo Huafu Garden, 585 South Zhonghua Street
City State Country
Shijiazhuang, Hebei 050091, China
Company
Jiangsu Jiatai Chemical Co., Ltd.
Address
17 Beijing West Road
City State Country
Nanjing 210024, China
Company
Red Sun Group Corporation
Address
19/F, Golden Eagle International Plaza, 89 Hanzhong Road
City State Country
Nanjing 210029, China
Company
Simagchem Corporation
Address
27/G, International Trade Gold Beach Building, Lujiang Road
City State Country
Xiamen, China
Company
Hebei Golhil Chemicals Co., Ltd. (Formerly Hebei Qifeng Chemical Ind.)
Address
Guchengqiao, Tongda Road
City State Country
Jinzhou City, Hebei 052260, China
Company
Jiangsu Xuzhou Shennong Chemicals Co., Ltd.
Address
36-1-601, Greenland Century City
City State Country
Xuzhou City, Jiangsu Province 221004, China
Company
Jiangsu FFC Chemicals Ltd. (FFC Chemical Ltd. Group)
Address
1101-No. 1, Building 2-405 Lane, Changning Road
City State Country
Shanghai 200050, China
Company
Zhejiang Heben Pesticide &amp; Chemicals Co., Ltd.
Address
Yanjiang Industrial Area, Lucheng Wenzhou
City State Country
Zhejiang 325000, China
Company
Hunan Haili Chemical Industry Co., Ltd.
Address
251 Furong Road
City State Country
Central Changsha City, Hunan 410007, China
Company
Nantong Jiangshan Agrochemical &amp; Chemicals Co., Ltd.
Address
35 Yaogang Road
City State Country
Nantong, Jiangsu Province 226006, China
Company
FFC Chemical Ltd.
Address
1101-1-2-405 Lane, Changning Road
City State Country
Shanghai 200050, China
Company
Zhejiang Yongnong Chemical Industry Ltd.
Address
Room 2301, City Light Building. Northen Zone, Season 3 of Nature
City State Country
Xincheng Wenzhou 325000, China
Company
Sincerity Chemicals Co., Ltd. (Formerly Anhui Chizhou Sincerity)
Address
No. 318, West Xingcun Road
City State Country
Chizhou City Anhui Province 247000, China
Company
Hockley International Ltd.
Address
Hockley House, 354 Park Lane Poynton, Stockport
City State Country
Cheshire SK12 1RL, Great Britain
Company
Phosphoric Fertilizers Industry S.A.
Address
Syngrou Avenue 97
City State Country
11745 Athens, Greece
Company
P.T. Petrosida Gresik
Address
P.O. Box 102
City State Country
Gresik 61101, Indonesia
Company
Makhteshim Chemical Works Ltd. (Makhteshim Agan Group)
Address
Golan Street
City State Country
Airport City 70151, Israel
Company
King Chemicals Co., Ltd.
Address
3-1-12 Oyodo Minami, Kita-ku
City State Country
Osaka 531-0075, Japan
Company
Dongbu Fine Chemicals Co., Ltd. (Formerly Hahn Jung Chemicals Inc.)
Address
19/21F Dongbu Financial Center, Daechi-dong, Kangnam-gu
City State Country
Seoul 135-523, Korea
Company
Lerida Union Quimica, S.A., Fabrica de Fertilizantes y Fitosa
Address
Avenida Afueras, s/n.
City State Country
25173 Sudanell (Lleida), Spain
Directory of World Chemical Producers, Chemical Information Services, 9101 LBJ Frwy., Suite 310, Dallas, TX 75243, (214) 349-6200. Date downloaded: September 2009. Available from, as of Sept 15, 2011: https://www.chemicalinfo.com/dwcp
Diazinon - Registrants
Company
Helena Chemical Co
Address
225 Schilling Blvd., Suite 300
City, State, Zip
Collierville TN 38017
Phone
901/752-4410
Company
Bayer Healthcare LLC Animal Health Division
Address
PO Box 390
City, State, Zip
Shawnee Mission KS 66201
Phone
913/268-2751
Company
Makhteshim Chemical Works Ltd
Address
PO Box 60
City, State, Zip
Beer Sheva 84100 Israel
Phone
919/256-9356
Company
Drexel Chemical Company
Address
1700 Channel Avenue
City, State, Zip
Memphis TN 38113
Phone
901/774-4370
Company
Y-Tex Corporation
Address
PO Box 1450
City, State, Zip
Cody WY 82414
Phone
307/587-5515
Company
Hacco, Inc.
Address
110 Hopkins Drive
City, State, Zip
Randolph WI 53956
Phone
920/326-5141
Company
KMG-Bernuth, Inc
Address
9555 W. Sam Houston Pkwy South, Suite 600
City, State, Zip
Houston TX 77099
Phone
713/600-3800
Company
Makhteshim-Agan of North America Inc
Address
4515 Falls of Neuse Rd, Suite 300
City, State, Zip
Raleigh NC 27609
Phone
919/256-9356
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon. (333-41-5). Available from, as of Sept 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/

12.3 Methods of Manufacturing (Complete)

Diazinon is produced by condensation of isobutyramidine with acetoacetate to yield the intermediate 2-isopropyl-4-methylpyrimidine, which is transformed into the final product by treatment with diethylthiophosphoric acid.
Muller F et al; Ullmann's Encyclopedia of Industrial Chemistry 7th ed. (1999-2011). NY, NY: John Wiley & Sons; Acaricides. Online Posting Date: July 15, 2009.
REACTION OF 2-ISOPROPYL-4-HYDROXY-6-METHYL-PYRIMIDINE & O,O-DIETHYL PHOSPHOROCHLORIDOTHIOATE.
SRI

12.4 General Manufacturing Information (Complete)

The WHO Recommended Classification of Pesticides by Hazard identifies diazinon (technical grade) as Class II: moderately hazardous; Main Use: insecticide.
WHO International Programme on Chemical Safety; The WHO Recommended Classification of Pesticides by Hazard and Guidelines to Classification 2009 p.26 (2010)
Known as Spectracide and other trade names, diazinon was one of the most widely used insecticides in the U.S. for household lawn and garden pest control (up to 70% of the 13 million pounds used each year), indoor residential crack and crevice treatments and pet collars (up to 5% of all use), and agricultural pest control (about 30% of all use). ... All indoor residential use product registrations were cancelled and retail sale of these products ended as of December 31, 2002. All outdoor residential use product registrations must be cancelled and retail sale must end by December 31, 2004. After that time, a buy-back program will help remove remaining outdoor diazinon residential use products from the market and prevent further sale.
USEPA/OPPTS; Interim Reregistration Eligibility Decision Facts on Diazinon (333-41-5). USEPA-738-R-04-007 (May 2004). Available from, as of November 20, 2011: https://www.epa.gov/pesticides/reregistration/status.htm

12.5 Formulations / Preparations (Complete)

Dust; emulsifiable and oil solutions, granule, seed dressing; ULV, wettable powder.
Mester, R.T.,Sine, C. (eds.) Crop Protection Handbook Volume 97. Meisterpro. Willoughby,OH. 2011, p. 349
Mester, R.T.,Sine, C. (eds.) Crop Protection Handbook Volume 97. Meisterpro. Willoughby,OH. 2011, p. 349
Formulation types: capsule suspension; dustable powder; powder for dry seed treatment; emulsifiable concentrate; emulsion, oil in water; smoke tablet; granule; cold fogging concentrate; suspension concentrate for direct application; wettable powder; aerosol; coating agent.
MacBean C, ed. Diazinon (333-41-5). In: The e-Pesticide Manual, 15th Edition, Version 5.0.1 (2010). Surrey UK, British Crop Protection Council.
Diazinon AG500 Insecticide (Helena Chemical Company): Diazinon 48%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Co-Ral Plus Insecticide Cattle Ear Tag (Bayer Healthcare LLC): Coumaphos 20%, Diazinon 20%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Corathon (Bayer Healthcare LLC): Coumaphos 15%; Diazinon 35%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazol Diazinon Technical Stabilized AG (Makhteshim Chemical Works Ltd): Diazinon 92%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazol (Diazinon) Stabilized Oil Concentrate AG (Makhteshim Chemical Works Ltd): Diazinon 87%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Drexel Diazinon Insecticide (Drexel Chemical Company): Diazinon 48.2%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazinon Insecticide (Drexel Chemical Company): Diazinon 48.2%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazinon 50WP Insecticide (Drexel Chemical Company): Diazinon 50%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazinon Diazinon Technical AG (Drexel Chemical Company): Diazinon 87%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Optimizer Insecticide Ear Tag (Y-Tex Corporation): Diazinon 21%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Warrior Insecticide Cattle Ear Tag (Y-Tex Corporation): Diazinon 30%; Chlorpyrifos 10%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazinon Lawn & Garden WBC (Hacco, Inc): Diazinon 22.4%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Terminator Insecticide Cattle Ear Tag (KMG-Bernuth, Inc): Diazinon 20%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Patriot Insecticide Cattle Ear Tag (KMG-Bernuth, Inc): Diazinon 40%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazinon AG500 (Makhteshim-Agan of North America Inc): Diazinon 48%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazinon 50W (Makhteshim-Agan of North America Inc): Diazinon 50%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/
Diazinon AG600 (Makhteshim-Agan of North America Inc): Diazinon 56%.
National Pesticide Information Retrieval System's USEPA/OPP Chemical Ingredients Database on Diazinon (333-41-5). Available from, as of September 6, 2011: https://npirspublic.ceris.purdue.edu/ppis/

12.6 Consumption Patterns (Complete)

Agricultural use of diazinon in the United States: almonds (19.9%), plums (9.5%), peaches (8.4%), walnuts (4.6%), lettuce (4.5%), nectarines (4.2%), sweet corn (4.2%), tobacco (3.4%), apples (3.2%), and all citrus (2.9%).
USGS; Pesticide 1992 Annual Use Map for Diazinon (333-41-5). Available from, as of Jan 23, 2001: https://ca.water.usgs.gov/pnsp/use92/
Total agricultural use of diazinon was 1.05X10+6 lbs in 1992.
USGS; Pesticide 1992 Annual Use Map for Diazinon (333-41-5). Available from, as of Jan 23, 2001: https://ca.water.usgs.gov/pnsp/use92/
Approximately 13 million lbs active ingredient of diazinon are used annually.
USEPA/OPPTS; Interim Reregistration Eligibility Decision (RED) on Diazinon (333-41-5). p.5 USEPA-738-R-04-006 (May 2004). Available from, as of November 20, 2011: https://www.epa.gov/pesticides/reregistration/status.htm

12.7 U.S. Production (Complete)

(1982) 2.63X10+9 G (CONSUMPTION)
SRI

Production volumes for non-confidential chemicals reported under the Inventory Update Rule.

Year
1986
Production Range (pounds)
No Reports
Year
1990
Production Range (pounds)
No Reports
Year
1994
Production Range (pounds)
10 thousand - 500 thousand
Year
1998
Production Range (pounds)
No Reports
Year
2002
Production Range (pounds)
No Reports

[US EPA; Non-confidential Production Volume Information Submitted by Companies for Chemicals Under the 1986-2002 Inventory Update Rule (IUR). Phosphorothioic acid, O,O-diethyl O-

6-methyl-2-(1-methylethyl)-4-pyrimidinyl] ester (333-41-5). Available from, as of August 31, 2011: https://www.epa.gov/oppt/iur/tools/data/2002-vol.html

12.8 U.S. Imports (Complete)

(1978) 1.60X10+7 G
SRI
(1982) 6.41X10+7 G
SRI

13 Laboratory Methods

13.1 Analytic Laboratory Methods (Complete)

Method: NIOSH 5600, Issue 1; Procedure: gas chromatography, flame photometric detection; Analyte: diazinon; Matrix: air; Detection Limit: 0.04 ug/sample.
CDC; NIOSH Manual of Analytical Methods, 4th ed. Diazinon (333-41-5). Available from, as of September 9, 2011: https://www.cdc.gov/niosh/docs/2003-154/
Method: OSHA 62; Procedure: gas chromatography using a flame photometric detector; Analyte: diazinon; Matrix: air; Detection Limit: 0.0030 mg/cu m (0.24 ppb).
U.S. Department of Labor/Occupational Safety and Health Administration's Index of Sampling and Analytical Methods. Diazinon (333-41-5). Available from, as of September 10, 2011: https://www.osha.gov/dts/sltc/methods/toc.html
Method 1618: Organo-halide and organophosphorus pesticides and phenoxy-acid herbicides by capillary column gas chromatography. This method is used for determination of ... organophosphorus pesticides in waters, soils, sediments, and sludges. Capillary column gas chromatography with flame photometric detector is used. Recovery is 86.9 percent and the relative standard deviation is 4.6 percent.
USEPA; Analytical Methods for the National Sewage Sludge Survey. 1988
AOAC Method 970.53. Organophosphorus Pesticide Residues, Single sweep oscillographic polarographic confirmatory method (for Diazinon).
Association of Official Analytical Chemists. Official Methods of Analysis. 15th ed. and Supplements. Washington, DC: Association of Analytical Chemists, 1990, p. 289
AOAC Method 968.24. Organophosphorus Pesticide Residues, Sweep codistillation method (for Diazinon).
Association of Official Analytical Chemists. Official Methods of Analysis. 15th ed. and Supplements. Washington, DC: Association of Analytical Chemists, 1990, p. 287
AOAC Method 982.06. Diazinon in microencapsulated pesticide formulations, gas chromatographic method.
Association of Official Analytical Chemists. Official Methods of Analysis. 15th ed. and Supplements. Washington, DC: Association of Analytical Chemists, 1990, p. 200
Application of solid phase microextraction in the analysis of diazinon in a food plant(Chrysanthemum coronarium). Residues were extracted by SPME fiber from a biphasic water/plant tissues mixture and determined by GC-FPD.
Chen W et al; Environ Sci Technol 32: 3816-20 (1998)
Method: ASTM D5475; Procedure: gas chromatography with a nitrogen-phosphorus detector; Analyte: diazinon; Matrix: ground water and finished drinking water; Detection Limit: 0.25 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: EPA-NERL 525.2; Procedure: gas chromatography/mass spectrometry; Analyte: diazinon; Matrix: finished drinking water, source water, or drinking water in any treatment stage; Detection Limit: 0.11 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: EPA-OGWDW/TSC 526; Procedure: gas chromatography/mass spectrometry; Analyte: diazinon; Matrix: raw water and finished drinking water; Detection Limit: 0.015 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: EPA-OW/OST 1699; Procedure: high resolution gas chromatography combined with high resolution mass spectrometry; Analyte: diazinon; Matrix: water, soil, sediment, biosolids, and tissue; Detection Limit: 27 pg/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: EPA-RCA 8141B (GC-NPD); Procedure: gas chromatography with a nitrogen-phosphorus detector (NPD); Analyte: diazinon; Matrix: water, soil, waste samples; Detection Limit: not provided.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: EPA-RCA 8141B (GC-FPD); Procedure: gas chromatography with flame photometric detector; Analyte: diazinon; Matrix: water, soil, waste samples; Detection Limit: 10 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: EPA-TSC/NERL 507; Procedure: gas chromatography with a nitrogen-phosphorus detector; Analyte: diazinon; Matrix: ground water and finished drinking water; Detection Limit: 0.13 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-1104; Procedure: gas chromatography with electron capture detector; Analyte: diazinon; Matrix: filtered water; Detection Limit: 0.01 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-1126-95; Procedure: gas chromatography-mass spectrometry with select-ion monitoring; Analyte: diazinon; Matrix: natural water; Detection Limit: 0.008 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-1402-01; Procedure: gas chromatography with flame photometric detector; Analyte: diazinon; Matrix: filtered water; Detection Limit: 0.01 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-1433-01; Procedure: gas chromatography/mass spectrometry; Analyte: diazinon; Matrix: filtered wastewater and natural-water samples; Detection Limit: 0.07 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-3104; Procedure: gas chromatography with electron capture detector; Analyte: diazinon; Matrix: water and water-suspended-sediment mixtures; Detection Limit: 0.01 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-3402-03; Procedure: gas chromatography with flame photometric detector; Analyte: diazinon; Matrix: whole-water samples; Detection Limit: 0.0075 ug/L.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-5104; Procedure: gas chromatography with electron capture detector; Analyte: diazinon; Matrix: bottom material and suspended sediment; Detection Limit: 0.1 ug/kg.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-5404-02; Procedure: high-performance gel-permeation chromatography, gas chromatography; Analyte: diazinon; Matrix: bed-sediment (lake and stream), aqueous suspended-sediment, and soil samples; Detection Limit: 1.24 ug/kg.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Method: USGS-NWQL O-7104; Procedure: gas chromatography with electron capture detector; Analyte: diazinon; Matrix: bottom material and suspended sediment; Detection Limit: 0.1 ug/kg.
National Environmental Methods Index; Analytical, Test and Sampling Methods. Diazinon (333-41-5). Available from, as of September 7, 2011: https://www.nemi.gov
Diazinon was determined in wastewater using continuous flow methodologies coupled on line with high performance liquid chromatography using ultraviolet detection. Two continuous flow techniques (completely continuous flow and flow injection) both combined with two separation methods (liquid-liquid extraction and adsorption resins) were used. Adsorption resins proved more suitable for the low concentrations of pesticide, while liquid-liquid extraction was more selective. Sample throughput for both methods was about 15 per hour. No differences were seen in the chromatograms using either n-heptane (liquid-liquid) or methanol (resin). Preconcentration depends on flow rates in the liquid-liquid extraction and on time in the resin method.
Farran A et al; Int J Environ Anal Chem 31 (3/4): 245-56 (1988)
Product analysis by glc with FID ... Residues determined by glc with TID, FPD or MCD, by tlc, by paper chromatography, by single sweep oscillographic polarography, ... by lc followed by gc with gc, lc or tlc identification, ... or by super-critical CO2 extraction and gc/ms determination.
MacBean C, ed. Diazinon (333-41-5). In: The e-Pesticide Manual, 15th Edition, Version 5.0.1 (2010). Surrey UK, British Crop Protection Council.

14 Special References

14.1 Special Reports (Complete)

Eisler R; Diazinon Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review; Govt Reports Announcements & Index (GRA&I), Issue 24 (1986). Ecological and toxicological aspects were reviewed with special references to fishery and wildlife resources.
Tafuri J, Roberts J; Organophosphate Poisoning; Ann Emerg Med 16 (2): 193-202 (1987). Review of human insecticide diagnosis.
Mullins DE et al; Disposal of Concentrated Solution of Diazinon Using Organic Absorption and Chemical and Microbial Degradation; Pestic Sci 25 (3): 241-254 (1989).
DHEW/NCI; Bioassay of Diazinon for Possible Carcinogenicity (1979) Technical Rpt Series No. 137 DHEW Pub No. (NIH) 79-1392
USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Diazinon (July 2006). The RED summarizes the risk assessment conclusions and outlines any risk reduction measures necessary for the pesticide to continue to be registered in the U.S.[Available from, as of November 20, 2011: http://www.epa.gov/pesticides/reregistration/status.htm]

15 Synonyms and Identifiers

Synonyms

333-41-5

DIAZINON

G-24480

G 301

ALFA-TOX

ANTIGAL

BASUDIN

BASUDIN 10 G

BAZUDEN

CIAZINON

DACUTOX

DASSITOX

DAZZEL

O,O-DIAETHYL-O-(2-ISOPROPYL-4-METHYL-PYRIMIDIN-6-YL)-MONOTHIOPHOSPHAT (GERMAN)

DIAZAJET

DIAZIDE

DIAZINON AG 500

DIAZINONE

DIAZITOL

DIAZOL

DICID

O,O-DIETHYL-O-(2-ISOPROPYL-4-METHYL-PYRIMIDIN-6-YL)-MONOTHIOFOSFAAT (DUTCH)

O,O-DIETHYL-O-(2-ISOPROPYL-4-METHYL-6-PYRIMIDINYL)-PHOSPHOROTHIOATE

O,O-DIETHYL O-(2-ISOPROPYL-6-METHYL-4-PYRIMIDINYL) PHOSPHOROTHIOATE

DIETHYL 2-ISOPROPYL-4-METHYL-6-PYRIMIDINYL PHOSPHOROTHIONATE

DIETHYL 4-(2-ISOPROPYL-6-METHYLPYRIMIDINYL)PHOSPHOROTHIONATE

O,O-DIETHYL-O-(2-ISOPROPYL-4-METHYL-6-PYRIMIDYL)PHOSPHOROTHIOATE

O,O-DIETHYL O-(2-ISOPROPYL-4-METHYL-6-PYRIMIDYL) THIONOPHOSPHATE

DIETHYL 2-ISOPROPYL-4-METHYL-6-PYRIMIDYL THIONOPHOSPHATE

O,O-DIETHYL 2-ISOPROPYL-4-METHYLPYRIMIDYL-6-THIOPHOSPHATE

O,O-DIETHYL O-6-METHYL-2-ISOPROPYL-4-PYRIMIDINYL PHOSPHOROTHIOATE

O,O-DIETIL-O-(2-ISOPROPIL-4-METIL-PIRIMIDIN-6-IL)-MONOTIOFOSFATO (ITALIAN)

DIMPYLAT

DIMPYLATE

DIPOFENE

DIZINON

DYZOL

ENT 19,507

USEPA/OPP Pesticide Code: 057801

EXODIN

FLYTROL

GALESAN

GARDENTOX

GEIGY 24480

O-2-ISOPROPYL-4-METHYLPYRIMIDYL-O,O-DIETHYL PHOSPHOROTHIOATE

ISOPROPYLMETHYLPYRIMIDYL DIETHYL THIOPHOSPHATE

KAYAZINON

KAYAZOL

KNOX-OUT

NCI-CO8673

NEDCIDOL

NEOCIDOL

NEOCIDOL (OIL)

NIPSAN

NUCIDOL

OLEODIAZINON

PHOSPHOROTHIOATE, O,O-DIETHYL O-6-(2-ISOPROPYL-4-METHYLPYRIMIDYL)

PHOSPHOROTHIOIC ACID, O,O-DIETHYL O-(ISOPROPYLMETHYLPYRIMIDINYL) ESTER

PHOSPHOROTHIOIC ACID, O,O-DIETHYL O-(2-ISOPROPYL-6-METHYL-4-PYRIMIDINYL) ESTER

PHOSPHOROTHIOIC ACID, O,O-DIETHYL O-(6-METHYL-2-(1-METHYLETHYL)-4-PYRIMIDINYL) ESTER

SAROLEX

SPECTRACIDE

SPECTRACIDE 25EC

THIOPHOSPHORIC ACID 2-ISOPROPYL-4-METHYL-6-PYRIMIDYL DIETHYL ESTER

15.1 Substance Title

DIAZINON

15.2 Shipping Name / Number DOT/UN/NA/IMO (Complete)

IMO 6.1; Organophosphorus pesticides, liquid, toxic; Organophosphorus pesticides, liquid, toxic, flammable, flashpoint not less than 23 °C; Organophosphorus pesticides, solid, toxic
UN 2783; Organophosphorus pesticides, solid, toxic
UN 2784; Organophosphorus pesticides, liquid, flammable, toxic, flashpoint less than 23 °C
UN 3017; Organophosphorus pesticides, liquid, toxic, flammable, flashpoint not less than 23 °C
UN 3018; Organophosphorus pesticides, liquid, toxic.
IMO 3.0; Organophosphorus pesticides, liquid, flammable, toxic, flashpoint less than 23 °C.

16 Administrative Information

16.1 Hazardous Substances DataBank Number

303

16.2 Last Revision Date

20120426

16.3 Last Review Date

Reviewed by SRP on 1/19/2012

16.4 Update History

Field Update on 2013-04-02, 1 fields added/edited/deleted

Complete Update on 2012-04-26, 4 fields added/edited/deleted

Complete Update on 2012-04-20, 70 fields added/edited/deleted

Field Update on 2010-09-07, 1 fields added/edited/deleted

Field Update on 2010-06-02, 4 fields added/edited/deleted

Field Update on 2008-09-02, 2 fields added/edited/deleted

Field Update on 2008-08-23, 1 fields added/edited/deleted

Field Update on 2008-08-22, 1 fields added/edited/deleted

Field Update on 2008-08-21, 1 fields added/edited/deleted

Field Update on 2008-08-15, 25 fields added/edited/deleted

Field Update on 2007-06-07, 1 fields added/edited/deleted

Field Update on 2006-04-18, 2 fields added/edited/deleted

Field Update on 2006-04-17, 2 fields added/edited/deleted

Complete Update on 2005-08-23, 2 fields added/edited/deleted

Field Update on 2005-04-29, 4 fields added/edited/deleted

Complete Update on 03/27/2003, 1 field added/edited/deleted.

Complete Update on 11/08/2002, 1 field added/edited/deleted.

Complete Update on 10/16/2002, 1 field added/edited/deleted.

Complete Update on 01/14/2002, 1 field added/edited/deleted.

Complete Update on 08/09/2001, 1 field added/edited/deleted.

Complete Update on 05/16/2001, 1 field added/edited/deleted.

Complete Update on 05/04/2001, 63 fields added/edited/deleted.

Complete Update on 03/28/2000, 1 field added/edited/deleted.

Complete Update on 03/09/2000, 1 field added/edited/deleted.

Complete Update on 02/09/2000, 1 field added/edited/deleted.

Complete Update on 02/08/2000, 1 field added/edited/deleted.

Complete Update on 02/02/2000, 1 field added/edited/deleted.

Complete Update on 12/27/1999, 1 field added/edited/deleted.

Complete Update on 11/18/1999, 1 field added/edited/deleted.

Complete Update on 09/21/1999, 1 field added/edited/deleted.

Complete Update on 08/26/1999, 1 field added/edited/deleted.

Complete Update on 07/20/1999, 4 fields added/edited/deleted.

Complete Update on 03/17/1999, 1 field added/edited/deleted.

Complete Update on 01/27/1999, 1 field added/edited/deleted.

Complete Update on 11/12/1998, 2 fields added/edited/deleted.

Field Update on 10/29/1998, 1 field added/edited/deleted.

Complete Update on 06/02/1998, 1 field added/edited/deleted.

Complete Update on 10/17/1997, 1 field added/edited/deleted.

Complete Update on 08/20/1997, 2 fields added/edited/deleted.

Complete Update on 08/11/1997, 1 field added/edited/deleted.

Complete Update on 05/08/1997, 1 field added/edited/deleted.

Complete Update on 04/01/1997, 2 fields added/edited/deleted.

Complete Update on 03/11/1997, 2 fields added/edited/deleted.

Complete Update on 02/07/1997, 4 fields added/edited/deleted.

Complete Update on 10/12/1996, 1 field added/edited/deleted.

Complete Update on 09/04/1996, 6 fields added/edited/deleted.

Complete Update on 05/09/1996, 1 field added/edited/deleted.

Complete Update on 01/18/1996, 1 field added/edited/deleted.

Complete Update on 11/10/1995, 1 field added/edited/deleted.

Complete Update on 01/18/1995, 1 field added/edited/deleted.

Complete Update on 12/19/1994, 1 field added/edited/deleted.

Complete Update on 07/22/1994, 1 field added/edited/deleted.

Complete Update on 05/05/1994, 1 field added/edited/deleted.

Complete Update on 03/25/1994, 1 field added/edited/deleted.

Complete Update on 09/02/1993, 1 field added/edited/deleted.

Complete Update on 08/07/1993, 1 field added/edited/deleted.

Complete Update on 08/04/1993, 1 field added/edited/deleted.

Field update on 12/12/1992, 1 field added/edited/deleted.

Complete Update on 09/03/1992, 1 field added/edited/deleted.

Complete Update on 01/23/1992, 1 field added/edited/deleted.

Complete Update on 09/26/1991, 1 field added/edited/deleted.

Complete Update on 09/10/1991, 64 fields added/edited/deleted.

Field Update on 05/14/1990, 1 field added/edited/deleted.

Field Update on 03/06/1990, 1 field added/edited/deleted.

Field Update on 01/15/1990, 1 field added/edited/deleted.

Complete Update on 01/11/1990, 29 fields added/edited/deleted.

Complete Update on 10/25/1985

Created 19830315 by GCF

CONTENTS