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Sulfur Dioxide

PubChem CID
1119
Structure
Sulfur Dioxide_small.png
Sulfur Dioxide_3D_Structure.png
Molecular Formula
Synonyms
  • sulfur dioxide
  • sulphur dioxide
  • Sulfurous anhydride
  • 7446-09-5
  • Sulfurous oxide
Molecular Weight
64.07 g/mol
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Dates
  • Create:
    2004-09-16
  • Modify:
    2025-01-04
Description
Sulfur dioxide is a colorless gas with a pungent odor. It is a liquid when under pressure, and it dissolves in water very easily. Sulfur dioxide in the air comes mainly from activities such as the burning of coal and oil at power plants or from copper smelting. In nature, sulfur dioxide can be released to the air from volcanic eruptions.
Sulfur Dioxide can cause developmental toxicity according to an independent committee of scientific and health experts.
Sulfur dioxide appears as a colorless gas with a choking or suffocating odor. Boiling point -10 °C. Heavier than air. Very toxic by inhalation and may irritate the eyes and mucous membranes. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. Used to manufacture chemicals, in paper pulping, in metal and food processing. Rate of onset: Immediate & Delayed Persistence: Minutes to hours Odor threshold: 1 ppm Source/use/other hazard: Disinfectant and preserving in breweries and food/canning; textile industry; batteries.

1 Structures

1.1 2D Structure

Chemical Structure Depiction
Sulfur Dioxide.png

1.2 3D Conformer

1.3 Crystal Structures

2 Names and Identifiers

2.1 Computed Descriptors

2.1.1 IUPAC Name

sulfur dioxide
Computed by Lexichem TK 2.7.0 (PubChem release 2021.10.14)

2.1.2 InChI

InChI=1S/O2S/c1-3-2
Computed by InChI 1.0.6 (PubChem release 2021.10.14)

2.1.3 InChIKey

RAHZWNYVWXNFOC-UHFFFAOYSA-N
Computed by InChI 1.0.6 (PubChem release 2021.10.14)

2.1.4 SMILES

O=S=O
Computed by OEChem 2.3.0 (PubChem release 2024.12.12)

2.2 Molecular Formula

O2S
Computed by PubChem 2.2 (PubChem release 2021.10.14)
SO2
SO2

2.3 Other Identifiers

2.3.1 CAS

7446-09-5

2.3.3 Deprecated CAS

12396-99-5, 1239882-82-6, 8014-94-6, 83008-56-4, 89125-89-3

2.3.4 European Community (EC) Number

231-195-2

2.3.5 UNII

2.3.6 UN Number

2.3.7 ChEBI ID

2.3.8 ChEMBL ID

2.3.9 DrugBank ID

2.3.10 DSSTox Substance ID

2.3.11 FEMA Number

2.3.12 HMDB ID

2.3.13 ICSC Number

2.3.14 KEGG ID

2.3.15 Nikkaji Number

2.3.16 RTECS Number

2.3.17 RXCUI

2.3.18 Wikidata

2.3.19 Wikipedia

2.4 Synonyms

2.4.1 MeSH Entry Terms

  • Sulfur Dioxide
  • Sulfurous Anhydride

2.4.2 Depositor-Supplied Synonyms

3 Chemical and Physical Properties

3.1 Computed Properties

Property Name
Molecular Weight
Property Value
64.07 g/mol
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
XLogP3-AA
Property Value
0.1
Reference
Computed by XLogP3 3.0 (PubChem release 2021.10.14)
Property Name
Hydrogen Bond Donor Count
Property Value
0
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Hydrogen Bond Acceptor Count
Property Value
3
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Rotatable Bond Count
Property Value
0
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Exact Mass
Property Value
63.96190041 Da
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
Monoisotopic Mass
Property Value
63.96190041 Da
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
Topological Polar Surface Area
Property Value
35.1 Ų
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Heavy Atom Count
Property Value
3
Reference
Computed by PubChem
Property Name
Formal Charge
Property Value
0
Reference
Computed by PubChem
Property Name
Complexity
Property Value
18.3
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Isotope Atom Count
Property Value
0
Reference
Computed by PubChem
Property Name
Defined Atom Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Undefined Atom Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Defined Bond Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Undefined Bond Stereocenter Count
Property Value
0
Reference
Computed by PubChem
Property Name
Covalently-Bonded Unit Count
Property Value
1
Reference
Computed by PubChem
Property Name
Compound Is Canonicalized
Property Value
Yes
Reference
Computed by PubChem (release 2021.10.14)

3.2 Experimental Properties

3.2.1 Physical Description

Sulfur dioxide appears as a colorless gas with a choking or suffocating odor. Boiling point -10 °C. Heavier than air. Very toxic by inhalation and may irritate the eyes and mucous membranes. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. Used to manufacture chemicals, in paper pulping, in metal and food processing. Rate of onset: Immediate & Delayed Persistence: Minutes to hours Odor threshold: 1 ppm Source/use/other hazard: Disinfectant and preserving in breweries and food/canning; textile industry; batteries.
Liquid
Colourless, non-flammable gas with strong pungent suffocating odour
Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14 degrees F. Shipped as a liquefied compressed gas.] [NIOSH]
COLOURLESS GAS OR COMPRESSED LIQUEFIED GAS WITH PUNGENT ODOUR.
Colorless gas with a characteristic, irritating, pungent odor.
Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14 °F. Shipped as a liquefied compressed gas.]

3.2.2 Color / Form

Colorless gas or liquid
Larranaga, M.D., Lewis, R.J. Sr., Lewis, R.A.; Hawley's Condensed Chemical Dictionary 16th Edition. John Wiley & Sons, Inc. Hoboken, NJ 2016., p. 1290
Colorless gas ... [Note: A liquid below 14 degrees F. Shipped as a liquefied compressed gas]
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg

3.2.3 Odor

Strong suffocating odor
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Cambridge, UK: Royal Society of Chemistry, 2013., p. 1659
... Characteristic, irritating, pungent odor ...
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg

3.2.4 Taste

Acid taste
International Labour Office. Encyclopedia of Occupational Health and Safety. Vols. I&II. Geneva, Switzerland: International Labour Office, 1983., p. 2122

3.2.5 Boiling Point

14 °F at 760 mmHg (EPA, 1998)
U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
-10 °C
-10.05 °C
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 4-92
-10.00 °C. @ 760.00 mm Hg
The Good Scents Company Information System
14 °F

3.2.6 Melting Point

-98.9 °F (EPA, 1998)
U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
-75.5 °C
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 4-92
-75.48 °C
-104 °F

3.2.7 Solubility

10 % (NIOSH, 2024)
In water, 1.07X10+5 mg/L at 21 °C
Venable CS, Fuwa T; Ind Eng Chem 14: 139-42 (1922)
Soluble in water
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 4-92
In water: 17.7% at 0 °C; 11.9% at 15 °C; 8.5% at 25 °C; 6.4% at 35 °C
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Cambridge, UK: Royal Society of Chemistry, 2013., p. 1659
Soluble in water ... forms sulfurous acid (H2SO3)
Larranaga, M.D., Lewis, R.J. Sr., Lewis, R.A.; Hawley's Condensed Chemical Dictionary 16th Edition. John Wiley & Sons, Inc. Hoboken, NJ 2016., p. 1290
For more Solubility (Complete) data for Sulfur dioxide (7 total), please visit the HSDB record page.
107 mg/mL at 21 °C
Solubility in water, ml/100ml at 25 °C: 8.5
10%

3.2.8 Density

1.434 (EPA, 1998) - Denser than water; will sink
U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
2.619 g/L
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 4-92
Density: 1.5 /liquid/
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Cambridge, UK: Royal Society of Chemistry, 2013., p. 1659
Density: 1.434 at 0 °C (liquid); vapor pressure: 2538 mm Hg at 21.1 °C
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. V5: 4106
Relative density (water = 1): 1.4 (liquid, -10 °C)
1.434
2.26(relative gas density)

3.2.9 Vapor Density

2.26 (EPA, 1998) - Heavier than air; will sink (Relative to Air)
U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
2.264 at 0 °C (Air = 1)
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. V5: 4106
Relative vapor density (air = 1): 2.25
2.26

3.2.10 Vapor Pressure

2432 mmHg at 68 °F (EPA, 1998)
U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
Vapor pressure (kPa): 230 at 10 °C; 330 at 20 °C; 462 at 30 °C; 630 at 40 °C
Weil ED et al; Sulfur Compounds. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 16 Jun 2006
Vapor pressure, kPa at 20 °C: 330
3.2 atm

3.2.11 Henry's Law Constant

Henry's Law constant = 8.10X10-4 atm-cu m/mol at 25 °C
Betterton EA; Henry's Law Constants of Soluble and Moderately Soluble Organic Gases: Effects on Aqueous Phase Chemistry. Gas Pollut Character Cycl. John Wiley and Sons, Inc. pp. 1-50 (1992)

3.2.12 Stability / Shelf Life

Stable under recommended storage conditions.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html
Extremely stable to heat, even up to 2000 °C
Weil ED, et al; Sulfur dioxide. Kirk-Othmer Encyclopedia of Chemical Technology (2006). John Wiley & Sons, Inc. Online Posting Date: June 16, 2006.

3.2.13 Autoignition Temperature

Not flammable (USCG, 1999)
U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.

3.2.14 Viscosity

Gas: 0.0124 mPa.s at 18 °C. Liquid: 0.368 mPa.s at 0 °C.
Environment Canada; Tech Info for Problem Spills: Sulfur Dioxide (Draft) p.3 (1985)

3.2.15 Corrosivity

Iron, steel, nickel, copper-nickel alloys, & inconel nickel-chromium-iron are satisfactory for dry or hot sulfur dioxide, but they are readily corroded below the dew point or by wet sulfur dioxide gas. Liquid sulfur dioxide produces serious corrosion of iron, brass, and copper at about 0.2 wt% or higher moisture content.
Weil ED, et al; Kirk-Othmer Encyclopedia of Chemical Technology. (2005). NY, NY: John Wiley & Sons; Sulfur Compounds. Online Posting Date: June 16, 2006.
Liquid sulfur dioxide will attack some forms of plastic, rubber, and coatings
Mackison, F. W., R. S. Stricoff, and L. J. Partridge, Jr. (eds.). NIOSH/OSHA - Occupational Health Guidelines for Chemical Hazards. DHHS(NIOSH) Publication No. 81-123 (3 VOLS). Washington, DC: U.S. Government Printing Office, Jan. 1981., p. 2
Corrodes aluminum
U.S. Coast Guard, Department of Transportation. CHRIS - Hazardous Chemical Data. Volume II. Washington, D.C.: U.S. Government Printing Office, 1984-5.

3.2.16 Heat of Vaporization

22.92 kJ/mol
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 6-131

3.2.17 Surface Tension

28.59 mN/m (liquid at 10 °C)
Environment Canada; Tech Info for Problem Spills: Sulfur Dioxide (Draft) p.4 (1985)

3.2.18 Ionization Potential

12.30 eV

3.2.19 Odor Threshold

Odor Threshold Low: 0.33 [ppm]

Odor Threshold High: 5.0 [ppm]

Detection odor threshold from AIHA (mean = 2.7)

4.70X10-1 ppm (recognition in air, chemically pure)
Fazzalari, F.A. (ed.). Compilation of Odor and Taste Threshold Values Data. ASTM Data Series DS 48A (Committee E-18). Philadelphia, PA: American Society for Testing and Materials, 1978., p. 153
Odor threshold: 0.1 ppm (low); 3.0 ppm (high)
Environment Canada; Tech Info for Problem Spills: Sulfur Dioxide (Draft) p.1 (1985)
Odor threshold: 1.1750 mg/cu m (low); 12.5000 mg/cu m (high); Irritating odor concn: 5.0 mg/cu m.
Ruth JH; Am Ind Hyg Assoc J 47: A-142-51 (1986)
The odor is detectable at 0.5 ppm, although concentrations above 6 ppm have been reported to produce instantaneous mucous membrane irritation.
Sullivan, J.B., Krieger G.R. (eds). Clinical Environmental Health and Toxic Exposures. Second edition. Lippincott Williams and Wilkins, Philadelphia, Pennsylvania 1999., p. 826

3.2.20 Refractive Index

Index of refraction: 1.3396 at 25 °C
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 4-137

3.2.21 Relative Evaporation Rate

Greater than 1 (Butyl acetate = 1)
Mackison, F. W., R. S. Stricoff, and L. J. Partridge, Jr. (eds.). NIOSH/OSHA - Occupational Health Guidelines for Chemical Hazards. DHHS(NIOSH) Publication No. 81-123 (3 VOLS). Washington, DC: U.S. Government Printing Office, Jan. 1981., p. 2

3.2.22 Kovats Retention Index

Standard polar
856 , 882

3.2.23 Other Experimental Properties

Heat of formation: -296.8 kJ/mol at 298.15 K; standard molar entropy: 248.2 J/K-mol at 298.15 K; heat capacity: 39.9 J/mol-K at constant pressure at 298.15 K /gas/
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 5-16
Heat of formation: -320.5 kJ/mol at 298.15 K /liquid/
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 5-16
Critical volume: 122 cu cm/mol
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 6-85
Dielectric constant: 16.3 at 298.2 K /liquid/
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 6-188
For more Other Experimental Properties (Complete) data for Sulfur dioxide (15 total), please visit the HSDB record page.

3.3 SpringerMaterials Properties

3.4 Chemical Classes

Toxic Gases & Vapors -> Corrosive Gases

3.4.1 Cosmetics

Cosmetics ingredient -> Colorant; Preservative/Stabilizer

3.4.2 Food Additives

ANTIMICROBIAL AGENT, ANTIOXIDANT, COLOR OR COLORING ADJUNCT, FLAVOR ENHANCER, FLAVORING AGENT OR ADJUVANT -> FDA Substance added to food

3.4.3 Fragrances

Fragrance Ingredient (Sulfur dioxide) -> IFRA transparency List

4 Spectral Information

4.1 1D NMR Spectra

1D NMR Spectra

4.2 Mass Spectrometry

4.2.1 GC-MS

1 of 4
View All
NIST Number
191
Library
Main library
Total Peaks
10
m/z Top Peak
64
m/z 2nd Highest
48
m/z 3rd Highest
32
Thumbnail
Thumbnail
2 of 4
View All
NIST Number
150707
Library
Replicate library
Total Peaks
11
m/z Top Peak
64
m/z 2nd Highest
48
m/z 3rd Highest
32
Thumbnail
Thumbnail

6 Chemical Vendors

7 Food Additives and Ingredients

7.1 Food Additive Classes

JECFA Functional Classes
ANTIOXIDANT;

7.2 FDA Substances Added to Food

Used for (Technical Effect)
ANTIMICROBIAL AGENT, ANTIOXIDANT, COLOR OR COLORING ADJUNCT, FLAVOR ENHANCER, FLAVORING AGENT OR ADJUVANT
Document Number (21 eCFR)
FEMA Number
3039
GRAS Number
3

7.3 Evaluations of the Joint FAO / WHO Expert Committee on Food Additives - JECFA

Chemical Name
SULFUR DIOXIDE
Evaluation Year
1998
ADI
0-0.7 mg/kg bw
Tox Monograph

8 Pharmacology and Biochemistry

8.1 MeSH Pharmacological Classification

Air Pollutants
Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or materials. Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS. (See all compounds classified as Air Pollutants.)

8.2 Bionecessity

The role of endogenous sulfur dioxide (SO2), an efficient gasotransmitter maintaining homeostasis, in the development of acute lung injury (ALI) remains unidentified. We aimed to investigate the role of endogenous SO2 in the pathogenesis of ALI. An oleic acid (OA)-induced ALI rat model was established. Endogenous SO2 levels, lung injury, oxidative stress markers and apoptosis were examined. OA-induced ALI rats showed a markedly downregulated endogenous SO2/aspartate aminotransferase 1 (AAT1)/AAT2 pathway and severe lung injury. Chemical colorimetry assays demonstrated upregulated reactive oxygen species generation and downregulated antioxidant capacity in OA-induced ALI rats. However, SO2 increased endogenous SO2 levels, protected against oxidative stress and alleviated ALI. Moreover, compared with OA-treated cells, in human alveolar epithelial cells SO2 downregulated O2(-) and OH(-) generation. In contrast, L-aspartic acid-beta-hydroxamate (HDX), an inhibitor of endogenous SO2 generating enzyme, promoted free radical generation, upregulated poly (ADP-ribose) polymerase expression, activated caspase-3, as well as promoted cell apoptosis. Importantly, apoptosis could be inhibited by the free radical scavengers glutathione (GSH) and N-acetyl-L-cysteine (NAC). The results suggest that SO2/AAT1/AAT2 pathway might protect against the development of OA-induced ALI by inhibiting oxidative stress.
Chen S et al; Lab Invest 95 (2): 142-56 (2015)
Sulfur dioxide (SO2) was previously regarded as a toxic gas in atmospheric pollutants. But it has been found to be endogenously generated from metabolism of sulfur-containing amino acids in mammals through transamination by aspartate aminotransferase (AAT). SO2 could be produced in cardiovascular tissues catalyzed by its synthase AAT. In recent years, studies revealed that SO2 had physiological effects on the cardiovascular system, including vasorelaxation and cardiac function regulation. In addition, the pathophysiological effects of SO2 were also determined. For example, SO2 ameliorated systemic hypertension and pulmonary hypertension, prevented the development of atherosclerosis, and protected against myocardial ischemia-reperfusion (I/R) injury and isoproterenol-induced myocardial injury. These findings suggested that endogenous SO2 was a novel gasotransmitter in the cardiovascular system and provided a new therapy target for cardiovascular diseases.
Huang Y et al; Oxid Med Cell Longev 2016: 8961951 (2016)
Gasotransmitters, such as nitric oxide, carbon monoxide and hydrogen sulfide, play important roles in life and have attracted great interest in scientists. In recent years, sulfur dioxide (SO2) has also been found to play important roles in mammals. The redox pathway is involved in the biological effects of SO2, such as the protective effect on myocardial ischemia reperfusion, myocardial injury, pulmonary hypertension and atherosclerosis. Ion channels, such as L-type calcium and adenosine triphosphate-sensitive potassium channels, as well as 3'-5'-cyclic guanosine monophosphate and 3'-5'-cyclic adenosine monophosphate pathways are also involved in the vasorelaxant effect of SO2. The mitogen-activated protein kinase pathway plays roles in vascular remodeling during pulmonary hypertension and vascular smooth muscle cell proliferation. Understanding these signaling mechanisms would help to clarify the pathophysiological effect and therapeutic potential of SO2.
Wang XB et al; Eur J Pharmacol 64: 94-9 (2015)

8.3 Absorption, Distribution and Excretion

Although the major route of absorption of the relevant sulfur compounds and particulate matter into the body is through the intestinal tract, the respiratory tract is the most vulnerable area for airborne materials. Most studies on both man and animals have indicated that 40 to 90% or more of inhaled sulfur dioxide is absorbed in the upper respiratory tract. Taken into the blood stream, it appears to be widely distributed throughout the body, metabolized, and excreted via the urinary tract. The deposition pattern of particulate matter varies with particle size, shape, and density, and also with airflow conditions. Deposited particles are largely phagocytized and transported to the mucociliary escalator, into the interstitium, or to the lymphatic system. The biological half-times range from days to years depending on their chemical composition. Soluble particles may dissolve in the mucous or aqueous lining of the lungs. In the first case, they will be eliminated via the mucociliary route. In the second, they may diffuse into the lymph or blood.
WHO; Environmental Health Criteria 8: Sulfur Oxides and Suspended Particulate Matter (1979); Available from, as of November 21, 2017: https://www.inchem.org/pages/ehc.html
Sulfur dioxide is highly soluble in aqueous media. Absorption after inhalation has been studied in rabbits and man. In rabbits, about 40% of the inhaled sulfur dioxide is absorbed in the nose and pharynx when concentrations of about 290 ug/cu m (0.1 ppm) are inhaled. At higher concentrations (29-290 mg/cu m, 10-100 ppm), the fraction absorbed is much higher (about 95%). The reasons for these different rates of absorption are not clear. In dogs, more than 99% of the inhaled sulfur dioxide is absorbed by the nose at exposure levels of 2.9-140 mg/cu m (1-50 ppm).
WHO; Environ Health Criteria: Sulfur Oxides and Suspended Particulate Matter p.50 (1979);
Sulfur dioxide is highly soluble in water and, therore, is absorbed efficiently in the upper respiratory tract. Two factors affecting the efficiency of absorption are the mode of breathing (oral versus oronasal) and ventilation rate. The nose filters out most inhaled sulfur dioxide, preventing its passage to sensitive irritant receptors at and below the larynx. At rest, most people (about 85%) breathe through the nose, providing protection against the pulmonary toxicity of sulfur dioxide. Mouth breathing, particularly at higher airflow rates, substantially increases the fraction of sulfur dioxide reaching the lung. Thus, voluntary hyperventilation or exercise at a level of exertion requiring oronasal breathing lowers the threshold for sulfur dioxide-induced respiratory symptoms and bronchomotor responsiveness. Deep lung penetration and toxicity are enhanced by oxidation and adsorption to submicrometer acidic particles.
Sullivan, J.B., Krieger G.R. (eds). Clinical Environmental Health and Toxic Exposures. Second edition. Lippincott Williams and Wilkins, Philadelphia, Pennsylvania 1999., p. 826
Radiolabeled sulfur dioxide is absorbed from the respiratory tract of experimental animals in the blood and is distributed throughout the body, concentrating in the liver, spleen, esophagus, and kidneys. It is metabolized to a variety of sulfur-containing compounds and is excreted principally via the urine as sulfate. Significant quantities of sulfur dioxide may be retained for a week or more in the lungs and trachea of experimental animals.
Sullivan, J.B., Krieger G.R. (eds). Clinical Environmental Health and Toxic Exposures. Second edition. Lippincott Williams and Wilkins, Philadelphia, Pennsylvania 1999., p. 826
While sulfur dioxide (SO(2)) has been previously known for its toxicological effects, it is now known to be produced endogenously in mammals from sulfur-containing amino acid L-cysteine. L-cysteine is catalyzed by cysteine dioxygenase (CDO) to L-cysteine sulfinate, which converts to beta-sulfinylpyruvate through transamination by aspartate aminotransferase (AAT), and finally spontaneously decomposes to pyruvate and SO(2). The present study explored endogenous SO(2) production, and AAT and CDO distribution in different rat tissue. SO(2) content was highest in stomach, followed by tissues in the right ventricle, left ventricle, cerebral gray matter, pancreas, lung, cerebral white matter, renal medulla, spleen, renal cortex and liver. AAT activity and AAT1 mRNA expression were highest in the left ventricle, while AAT1 protein expression was highest in the right ventricle. AAT2 and CDO mRNA expressions were both highest in liver tissue. AAT2 protein expression was highest in the renal medulla, but CDO protein expression was highest in liver tissue. In all tissues, AAT1 and AAT2 were mainly distributed in the cytoplasm rather than the nucleus. These observed differences among tissues endogenously generating SO(2) and associated enzymes are important in implicating the discovery of SO(2) as a novel endogenous signaling molecule.
Luo L et al; Biochem Biophys Res Commun 415 (1): 61-7 (2011)

8.4 Metabolism / Metabolites

... Sulfur dioxide (SO2) can be produced endogenously from normal metabolism of sulfur-containing amino acids. L-cysteine is oxidized via cysteine dioxygenase to L-cysteinesulfinate, and the latter can proceed through transamination by glutamate oxaloacetate transaminase (GOT) to beta-sulfinylpyruvate which decomposes spontaneously to pyruvate and SO2 ... Endogenous production of SO2 /was detected in spontaneous hypertensive rats/ in all cardiovascular tissues, including in heart, aorta, pulmonary artery, mesenteric artery, renal artery, tail artery and the plasma SO2 content. As the key enzyme producing SO2, GOT mRNA in cardiovascular system was detected and found to be located enrichedly in endothelial cells and vascular smooth muscle cells near the endothelial layer ...
Jin HF et al; Beijing da xue xue bao. Yi xue ban 39 (4): 423-5 (2007)
Once absorbed, sulfur dioxide appears to be metabolized rapidly to sulfate by the widely distributed enzyme sulfite oxidase. After it has been oxidized to sulfate, it becomes part of the large sulfate pool within the body. /It was reported/ relatively large differences in sulfite oxidase activity among five species: rats had the highest levels and rabbits the lowest. An inverse correlation was shown between enzyme activity and sensitivity to bisulfite toxicity. These results reflect species differences in rate of S-sulfonate formation.
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V54 166 (1992)

8.5 Biological Half-Life

No reports found; [TDR, p. 1098]
TDR - Ryan RP, Terry CE, Leffingwell SS (eds). Toxicology Desk Reference: The Toxic Exposure and Medical Monitoring Index, 5th Ed. Washington DC: Taylor & Francis, 1999., p. 1098

8.6 Biochemical Reactions

9 Use and Manufacturing

9.1 Uses

EPA CPDat Chemical and Product Categories
The Chemical and Products Database, a resource for exposure-relevant data on chemicals in consumer products, Scientific Data, volume 5, Article number: 180125 (2018), DOI:10.1038/sdata.2018.125
Sources/Uses
Formed as a byproduct of burning sulfur-containing materials; used for bleaching, disinfecting, and fumigating; [ACGIH] Used to preserve fruits and other foods; manufacture molasses, wine, and beer; bleach textile fibers; tan leather; pulp wood; manufacture lithium batteries and glass; treat water; and refine oil and metal; [HSDB]
ACGIH - Documentation of the TLVs and BEIs, 7th Ed. Cincinnati: ACGIH Worldwide, 2020.
Industrial Processes with risk of exposure

Aluminum Producing [Category: Industry]

Steel Producing [Category: Industry]

Forging [Category: Heat or Machine]

Molding and Core Making [Category: Foundry]

Petroleum Production and Refining [Category: Industry]

Battery Manufacturing [Category: Industry]

Smelting Copper or Lead [Category: Industry]

Pulp and Paper Processing [Category: Industry]

Textiles (Fiber & Fabric Manufacturing) [Category: Industry]

Using Disinfectants or Biocides [Category: Clean]

Farming (Pesticides) [Category: Industry]

Sewer and Wastewater Treatment [Category: Industry]

Leather Tanning and Processing [Category: Industry]

Photographic Processing [Category: Other]

Cement Producing [Category: Industry]

Glass Manufacturing [Category: Industry]

Metal Extraction and Refining [Category: Industry]

Activities with risk of exposure

Ceramics making [Category: Hobbies]

Glassblowing [Category: Hobbies]

Jewelry making [Category: Hobbies]

Burning biomass fuel for cooking and heating [Category: Environments]

For sulfur dioxide (USEPA/OPP Pesticide Code: 077601) 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 Database on Sulfur Dioxide (7446-09-5). Available from, as of October 10, 2017: https://npirspublic.ceris.purdue.edu/ppis/
Sulfur dioxide is used as a fungicide and preservative postharvest for grapes. /From table/
USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Inorganic Sulfites p.3 (May 2007). Available from, as of October 11, 2017: https://www.epa.gov/pesticides/reregistration/status.htm
Sulfur dioxide is ... used to manufacture hydrosulfites, to bleach wood pulp and paper, to process, disinfect, and bleach food, for waste and water treatment, in metal and ore refining, and in oil refining.
USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Inorganic Sulfites p.3 (May 2007). Available from, as of October 11, 2017: https://www.epa.gov/pesticides/reregistration/status.htm
Chemicals (H2SO4, salt cake, sulfites, hydrosulfites of potassium and sodium, thiosulfates, alum from shale, recovery of volatile substances), sulfite paper pulp, ore and metal refining, soybean protein, intermediates, solvent extraction of lubricating oils, bleaching agent for oils and starch, sulfonation of oils, disinfecting and fumigating, food additive (inhibition of browning, of enzyme-catalyzed reactions, bacterial growth), reducing agent, antioxidant.
Larranaga, M.D., Lewis, R.J. Sr., Lewis, R.A.; Hawley's Condensed Chemical Dictionary 16th Edition. John Wiley & Sons, Inc. Hoboken, NJ 2016., p. 1290
For more Uses (Complete) data for Sulfur dioxide (22 total), please visit the HSDB record page.

9.1.1 Use Classification

Chemical Classes -> Inorganic substances
Food additives
Fragrance Ingredients
ANTIOXIDANT; -> JECFA Functional Classes
Hazard Classes and Categories ->

9.1.2 Industry Uses

  • Reducing agent
  • Oxidizing/reducing agents
  • Not Known or Reasonably Ascertainable
  • Intermediates
  • Bleaching agents
  • Ion exchange agents
  • Agricultural chemicals (non-pesticidal)
  • Processing aids, not otherwise listed

9.1.3 Household Products

California Safe Cosmetics Program (CSCP)

Cosmetics product ingredient: Sulfur dioxide

Reason for Listing:

- Known to cause reproductive toxicity under Health and Safety Code section 25249.8 of the California Safe Drinking Water and Toxic Enforcement Act of 1986 (Prop 65)

- Listed as a chemical identified with non-cancer endpoints and listed with an inhalation or oral Reference Exposure Level by the California Office of Environmental Health Hazard Assessment under Health and Safety Code section 44360(b)(2)

Potential Health Impacts: Developmental Toxicity and Respiratory Toxicity

Product count: 5

Household & Commercial/Institutional Products

Information on 5 consumer products that contain Sulfur dioxide in the following categories is provided:

• Auto Products

• Inside the Home

9.2 Methods of Manufacturing

(1) By roasting pyrites in special furnaces. The gas is readily liquefied by cooling with ice and salt or at a pressure of three atmospheres. (2) By purifying and compressing sulfur dioxide gas from smelting operations. (3) By burning sulfur.
Larranaga, M.D., Lewis, R.J. Sr., Lewis, R.A.; Hawley's Condensed Chemical Dictionary 16th Edition. John Wiley & Sons, Inc. Hoboken, NJ 2016., p. 1290
... Produced commercially from the following raw materials: elemental sulfur; pyrites; sulfide ores of non-ferrous metals; waste sulfuric acid and sulfates; gypsum and anhydrite; hydrogen sulfide-containing waste gases; and flue gases from the combustion of sulfurous fossil fuels. It is most commonly produced by burning sulfur but can also be produced by burning pyrites in a special furnace or by purifying and compressing sulfur dioxide gas from smelting operations.
HHS/ATSDR; Toxicological Profile for Sulfur Dioxide p.109 PB/99/122020 (1998). Available from, as of October 17, 2017: https://www.atsdr.cdc.gov/toxprofiles/index.asp
... Produced by burning molten sulfur in a special burner with a controlled amount of air. The burner gas, free of dust and cooled, is dissolved in water in a series of two towers. In a third tower, the solution is sprayed at the top and flows down while steam is injected at the base. The gas issuing from the third tower is then cooled to remove most moisture and passed up a fourth tower against a countercurrent of sulfuric acid. The dried gas is liquefied by compression
HHS/ATSDR; Toxicological Profile for Sulfur Dioxide p.109 PB/99/122020 (1998). Available from, as of October 17, 2017: https://www.atsdr.cdc.gov/toxprofiles/index.asp
Sulfur dioxide can also be recovered commercially by liquefying gas obtained during smelting of non-ferrous metals such as lead, copper, and nickel.
HHS/ATSDR; Toxicological Profile for Sulfur Dioxide p.109 PB/99/122020 (1998). Available from, as of October 17, 2017: https://www.atsdr.cdc.gov/toxprofiles/index.asp

9.3 Formulations / Preparations

The Fruit Doctor/Compressed Sulfur Dioxide (Snowden Enterprises, Inc.): Active ingredient: sulfur dioxide 100%.
National Pesticide Information Retrieval System's Database on Sulfur Dioxide (7446-09-5). Available from, as of October 10, 2017: https://npirspublic.ceris.purdue.edu/ppis/
Sea Fresh 150 (Seaco Technologies, Inc.): Active ingredient: sulfur dioxide 100%.
National Pesticide Information Retrieval System's Database on Sulfur Dioxide (7446-09-5). Available from, as of October 10, 2017: https://npirspublic.ceris.purdue.edu/ppis/
Airgas Sulfur Dioxide (Airgas USA, LLC): Active ingredient: sulfur dioxide 99.9%.
National Pesticide Information Retrieval System's Database on Sulfur Dioxide (7446-09-5). Available from, as of October 10, 2017: https://npirspublic.ceris.purdue.edu/ppis/
The sulfur dioxide products are formulated as a compressed liquid that converts to a gas upon release.
USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Inorganic Sulfites p.2 (May 2007). Available from, as of October 11, 2017: https://www.epa.gov/pesticides/reregistration/status.htm
For more Formulations/Preparations (Complete) data for Sulfur dioxide (6 total), please visit the HSDB record page.

9.4 Consumption Patterns

CHEMICAL PROFILE: Sulfur Dioxide. End-use pattern for sulfur dioxide in 1985.

Table: End-use Pattern for Sulfur dioxide in 1985

End-use
Hydrosulfites and other chemicals
Percent (%)
47
End-use
Pulp and paper
Percent (%)
20
End-use
Food and agriculture (mainly corn processing)
Percent (%)
15
End-use
Water and waste treatment
Percent (%)
6
End-use
Metal and ore refining
Percent (%)
6
End-use
Other (including oil refining)
Percent (%)
6

Anonymous; Chemical Marketing Reporter, 228 (11): 00 (1985); 9 September 1985

CHEMICAL PROFILE: Sulfur Dioxide. End-use pattern for sulfur dioxide in 1988.

Table: End-use Pattern for Sulfur dioxide in 1988

End-use
Hydrosulfites and other chemicals
Percent (%)
40
End-use
Pulp and paper
Percent (%)
20
End-use
Food and agriculture (mainly corn processing)
Percent (%)
16
End-use
Water and waste treatment
Percent (%)
10
End-use
Metal and ore refining
Percent (%)
6
End-use
Oil refining
Percent (%)
4
End-use
Other
Percent (%)
4

Anonymous; Chemical Marketing Reporter, 234 (11): 54 (1988); 12 September 1988

CHEMICAL PROFILE: Sulfur Dioxide. End-use pattern for sulfur dioxide in 1991.

Table: End-use Pattern for Sulfur dioxide in 1991

End-use
Hydrosulfites and other chemicals
Percent (%)
40
End-use
Pulp and paper
Percent (%)
20
End-use
Water and waste treatment
Percent (%)
15
End-use
Food and agriculture (mainly corn processing)
Percent (%)
14
End-use
Metal and ore refining
Percent (%)
5
End-use
Oil refining
Percent (%)
1
End-use
Other
Percent (%)
5

Anonymous; Chemical Marketing Reporter, 240 (10): 42 (1991); 2 September 1991

CHEMICAL PROFILE: Sulfur Dioxide. End-use pattern for sulfur dioxide in 1994.

Table: End-use Pattern for Sulfur dioxide in 1994

End-use
Hydrosulfites and other chemicals
Percent (%)
40
End-use
Pulp and paper
Percent (%)
23
End-use
Food and agriculture (mainly corn processing)
Percent (%)
14
End-use
Water and waste treatment
Percent (%)
9
End-use
Metal and ore refining
Percent (%)
6
End-use
Oil recovery and refining
Percent (%)
4
End-use
Miscellaneous (including sulfonation of oils, and as a reducing agent or antioxidant)
Percent (%)
4

Anonymous; Chemical Marketing Reporter, 246 (8): 33 (1994); 22 August 1994
For more Consumption Patterns (Complete) data for Sulfur dioxide (16 total), please visit the HSDB record page.

9.5 U.S. Production

Aggregated Product Volume

2019: 207,991,996 lb

2018: 218,842,940 lb

2017: 218,909,554 lb

2016: 218,950,643 lb

(1977) 1.39X10+11 G
SRI
(1982) 1.18X10+11 G
SRI
(1985) 1.18X10+11 g
CHEMICAL PRODUCTS SYNOPSIS: Sulfur Dioxide, 1985
(1983) 1.21X10+5 short tons
BUREAU OF THE CENSUS. CURRENT INDUSTRIAL REPORTS, INORGANIC CHEMICALS, 1987
For more U.S. Production (Complete) data for Sulfur dioxide (17 total), please visit the HSDB record page.

9.6 U.S. Imports

(1977) 5.17X10+10 G
SRI
(1982) 2.26X10+10 G
SRI
(1985) 2.33X10+7 g
BUREAU OF THE CENSUS. U.S. IMPORTS FOR CONSUMPTION AND GENERAL IMPORTS 1985 p.1-574
(1986) 5.72X10+4 short tons
BUREAU OF THE CENSUS. US IMPORTS FOR CONSUMPTION AND GENERAL IMPORTS 1986 P.1-520
For more U.S. Imports (Complete) data for Sulfur dioxide (7 total), please visit the HSDB record page.

9.7 U.S. Exports

(1978) 1.62X10+9 G
SRI
(1983) 5.38X10+9 G
SRI
(1985) 1.60X10+9 g
BUREAU OF THE CENSUS. U.S. EXPORTS, SCHEDULE E, 1985 p.2-92
(1987) 1.88X10+5 lb
BUREAU OF THE CENSUS. U. S. EXPORTS, SCHEDULE E, DECEMBER 1987, P.2-99
For more U.S. Exports (Complete) data for Sulfur dioxide (6 total), please visit the HSDB record page.

9.8 General Manufacturing Information

Industry Processing Sectors
  • All Other Basic Organic Chemical Manufacturing
  • Electrical Equipment, Appliance, and Component Manufacturing
  • All Other Basic Inorganic Chemical Manufacturing
  • Food, beverage, and tobacco product manufacturing
  • Mining (except Oil and Gas) and support activities
  • Not Known or Reasonably Ascertainable
  • Utilities
  • Paper Manufacturing
EPA TSCA Commercial Activity Status
Sulfur dioxide: ACTIVE

10 Identification

10.1 Analytic Laboratory Methods

Method: NIOSH 3800, Issue 1; Procedure: extractive fourier transform infrared spectrometry; Analyte: sulfur dioxide; Matrix: air; Detection Limit: 0.35 ppm.
CDC; NIOSH Manual of Analytical Methods, 4th ed. Sulfur Dioxide (7446-09-5). Available from, as of October 11, 2017: https://www.cdc.gov/niosh/docs/2003-154/
Method: NIOSH 6004, Issue 2; Procedure: ion chromatography; Analyte: sulfur dioxide; Matrix: air; Detection Limit: 3 ug SO2 per sample.
CDC; NIOSH Manual of Analytical Methods, 4th ed. Sulfur Dioxide (7446-09-5). Available from, as of October 11, 2017: https://www.cdc.gov/niosh/docs/2003-154/
Method: OSHA ID-104; Procedure: ion chromatography; Analyte: sulfur dioxide; Matrix: air; Detection Limit: 0.0041 ppm (qualitative), 0.010 ppm (quantitative).
U.S. Department of Labor/Occupational Safety and Health Administration's Index of Sampling and Analytical Methods. Sulfur Dioxide (7446-09-5). Available from, as of October 11, 2017: https://www.osha.gov/dts/sltc/methods/toc.html
Method: OSHA ID-200; Procedure: ion chromatography; Analyte: sulfur dioxide; Matrix: air; Detection Limit: 0.004 ppm (qualitative), 0.013 ppm (quantitative).
U.S. Department of Labor/Occupational Safety and Health Administration's Index of Sampling and Analytical Methods. Sulfur Dioxide (7446-09-5). Available from, as of October 11, 2017: https://www.osha.gov/dts/sltc/methods/toc.html
For more Analytic Laboratory Methods (Complete) data for Sulfur dioxide (13 total), please visit the HSDB record page.

10.2 NIOSH Analytical Methods

11 Safety and Hazards

11.1 Hazards Identification

ERG Hazard Classes
Toxic/poison by inhalation (TIH/PIH)

11.1.1 GHS Classification

1 of 5
View All
Note
Pictograms displayed are for 83.9% (2207 of 2632) of reports that indicate hazard statements. This chemical does not meet GHS hazard criteria for 16.1% (425 of 2632) of reports.
Pictogram(s)
Compressed Gas
Corrosive
Acute Toxic
Signal
Danger
GHS Hazard Statements

H280 (19.4%): Contains gas under pressure; may explode if heated [Warning Gases under pressure]

H314 (83.8%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]

H331 (82.3%): Toxic if inhaled [Danger Acute toxicity, inhalation]

Precautionary Statement Codes

P260, P261, P264, P271, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P363, P403+P233, P405, P410+P403, and P501

(The corresponding statement to each P-code can be found at the GHS Classification page.)

ECHA C&L Notifications Summary

Aggregated GHS information provided per 2632 reports by companies from 29 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Reported as not meeting GHS hazard criteria per 425 of 2632 reports by companies. For more detailed information, please visit ECHA C&L website.

There are 28 notifications provided by 2207 of 2632 reports by companies with hazard statement code(s).

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown.

11.1.2 Hazard Classes and Categories

Press. Gas (Comp.) (19.4%)

Skin Corr. 1B (83.8%)

Acute Tox. 3 (82.3%)

Acute toxicity - category 3

Skin corrosion - category 1B

Gases under pressure

11.1.3 NFPA Hazard Classification

1 of 2
View All
NFPA 704 Diamond
3-0-0
NFPA Health Rating
3 - Materials that, under emergency conditions, can cause serious or permanent injury.
NFPA Fire Rating
0 - Materials that will not burn under typical fire conditions, including intrinsically noncombustible materials such as concrete, stone, and sand.
NFPA Instability Rating
0 - Materials that in themselves are normally stable, even under fire conditions.

11.1.4 Highly Hazardous Substance

OSHA Highly Hazardous Chemicals, Toxics and Reactives
  • Chemical: Sulfur Dioxide (liquid)
  • Threshold: 1000 [lb]
  • Note: Sulfur Dioxide (liquid) in quantities at or above above 1000lb presents a potential for a catastrophic event as a toxic or reactive highly hazardous chemical.

11.1.5 Health Hazards

It may cause death or permanent injury after very short exposure to small quantities. 1,000 ppm causes death in from 10 minutes to several hours by respiratory depression. It is an eye and respiratory tract irritant. Persons with asthma, subnormal pulmonary functions or cardiovascular disease are at a greater risk. (EPA, 1998)
U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
ERG 2024, Guide 125 (Sulfur dioxide)

· TOXIC and/or CORROSIVE; may be fatal if inhaled, ingested or absorbed through skin.

· Vapors are extremely irritating and corrosive.

· Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.

· Fire will produce irritating, corrosive and/or toxic gases.

· Runoff from fire control or dilution water may cause environmental contamination.

11.1.6 Fire Hazards

Containers may explode in heat of fire or they may rupture and release irritating toxic sulfur dioxide. Sulfur dioxide has explosive properties when it comes in contact with sodium hydride; potassium chlorate at elevated temperatures; ethanol; ether; zinc ethylsulfurinate at very cool temperatures (-15C); fluorine; chlorine trifluoride and chlorates. It will react with water or steam to produce toxic and corrosive fumes. When the liquid is heated it may release irritating, toxic sulfur dioxide gas. Avoid ammonia, monocesium or monopotassium acetylide; dicesium monoxide; iron (II) oxide; tin oxide; lead (IV) oxide; chromium; manganese; molten sodium, powder aluminum and rubidium. Sulfur dioxide has explosive properties when it comes in contact with sodium hydride; potassium chlorate at elevated temperatures; ethanol; ether; zinc ethylsulfurinate at very cool temperatures (-15C); fluorine; chlorine trifluoride and chlorates. It will react with water or steam to produce toxic and corrosive fumes. Hazardous polymerization may not occur. (EPA, 1998)
U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
ERG 2024, Guide 125 (Sulfur dioxide)

· Some may burn but none ignite readily.

· Vapors from liquefied gas are initially heavier than air and spread along ground.

· Some of these materials may react violently with water.

· Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief devices.

· Containers may explode when heated.

· Ruptured cylinders may rocket.

· For UN1005: Anhydrous ammonia, at high concentrations in confined spaces, presents a flammability risk if a source of ignition is introduced.

Not combustible. Heating will cause rise in pressure with risk of bursting.

11.1.7 Hazards Summary

Sulfur dioxide is a colorless gas with a pungent odor. It is a liquid when under pressure, and it dissolves in water very easily. Sulfur dioxide in the air comes mainly from activities such as the burning of coal and oil at power plants or from copper smelting. In nature, sulfur dioxide can be released to the air from volcanic eruptions.
Listed as one of major irritant airborne toxicants; [LaDou, p. 523] Possible frostbite from contact with liquid; [NIOSH] In the presence of water and acid, metabisulfite, a preservative, can generate toxic amounts of SO2. [ATSDR Med. Manage. Guidelines] The following chemicals can release SO2 when spilled in water: Sulfur chlorides; Sodium, Potassium, Calcium & Zinc hydrosulfite; and Thionyl chloride. [ERG 2016] See the Process, Toxic Gas from Spilling Chemical in Water. Sulfur dioxide is fibrogenic to the lungs in the context of an acute inhalation exposure complicated by bronchiolitis obliterans. [LaDou, p. 383]
LaDou - LaDou J, Harrison R (eds). Current Occupational & Environmental Medicine, 5th Ed. New York: McGraw-Hill, 2014., p. 523
LaDou - LaDou J, Harrison R (eds). Current Occupational & Environmental Medicine, 5th Ed. New York: McGraw-Hill, 2014., p. 383
The major hazards encountered in the use and handling of sulfur dioxide stem from its toxicologic properties. Exposure to this strong-smelling, colorless gas or liquid (compressed gas) may occur from its use as a fumigant, as an intermediate in the manufacture of sulfuric acid and other sulfur compounds, in oil, mineral, food and paper processing, and in water treatment. Effects from exposure may include contact burns to the eyes, skin, and mucous membranes, frostbite, bronchoconstriction, and pulmonary edema. Engineering controls, including local exhaust ventilation, should be used to maintain sulfur dioxide at or below the permissible limit. In activities and situations where over-exposure may occur, wear chemical protective clothing and a self-contained breathing apparatus. If contact should occur, immediately remove contaminated clothing (to be left at worksite for cleaning), irrigate exposed eyes with copiousamounts of tepid water for at least 15 minutes, flush exposed skin with water, and treat for possible frostbite. Emergency eyewash facilities should be available in sulfur dioxide work areas. While sulfur dioxide does not ignite easily, it may burn, and cylinders of the compressed material can explode in the heat of a fire. For fires involving sulfur dioxide, extinguish with dry chemical, CO2, Halon, water spray, fog, or standard foam. If water is used, apply from as far a distance as possible because material will react with water to form toxic and corrosive fumes. Sulfur dioxide may be shipped domestically via air (cargo only), rail (cargo only), road, and water, in containers bearing the label, "Nonflammable gas." Sulfur dioxide should be stored in tightly closed containers, in cool, well-ventilated areas, and away from sources of physical damage. For spills of liquid sulfur dioxide, first evacuate area for 50 feet in all directions, use water spray to reduce vapor, and neutralize spilled material with limestone, soda ash, or lime. Keep material from entering water sources and sewers. Before implementing land disposal of sulfur dioxide waste, consult with environmental regulatory agencies for guidance.

11.1.8 Fire Potential

Not combustible. /Sulfur dioxide, liquefied/
National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 49-140
... Not flammable with air.
Seiler, H.G., H. Sigel and A. Sigel (eds.). Handbook on the Toxicity of Inorganic Compounds. New York, NY: Marcel Dekker, Inc. 1988., p. 643

11.1.9 Skin, Eye, and Respiratory Irritations

Vapors cause severe irritation of eyes and throat ...
U.S. Coast Guard, Department of Transportation. CHRIS - Hazardous Chemical Data. Volume II. Washington, D.C.: U.S. Government Printing Office, 1984-5.
Irritating to ... respiraory system and skin.
Commission of the European Communities. Legislation on Dangerous Substances - Classification and Labelling in the European Communities. Vol. II. London and Trotman Ltd., 1989., p. 138
HAZARD WARNING: Because of the high solubility of sulfur dioxide, it is extremely irritating to the eyes and upper respiratory tract, warning the exposed individual to escape before serious damage occurs.
Sullivan, J.B., Krieger G.R. (eds). Clinical Environmental Health and Toxic Exposures. Second edition. Lippincott Williams and Wilkins, Philadelphia, Pennsylvania 1999., p. 826

11.2 Safety and Hazard Properties

11.2.1 Acute Exposure Guideline Levels (AEGLs)

11.2.1.1 AEGLs Table
AEGLs
AEGL 1: Notable discomfort, irritation, or certain asymptomatic non-sensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure (Unit: ppm)
10 min
0.20
30 min
0.20
60 min
0.20
4 hr
0.20
8 hr
0.20
AEGLs
AEGL 2: Irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape (Unit: ppm)
10 min
0.75
30 min
0.75
60 min
0.75
4 hr
0.75
8 hr
0.75
AEGLs
AEGL 3: Life-threatening health effects or death (Unit: ppm)
10 min
30
30 min
30
60 min
30
4 hr
19
8 hr
9.6
11.2.1.2 AEGLs Notes
AEGLs Status: Final

11.2.2 Flammable Limits

Flammability
Nonflammable Gas

11.2.3 Critical Temperature & Pressure

Critical temperature: 430.64 K; critical pressure: 7.884 Mpa
Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 6-85

11.2.4 Physical Dangers

The gas is heavier than air.

11.2.5 OSHA Standards

Permissible Exposure Limit: Table Z-1 8-hr Time Weighted Avg: 5 ppm (13 mg/cu m).
29 CFR 1910.1000 (USDOL); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov
Vacated 1989 OSHA PEL TWA 2ppm (5 mg/cu m); STEL 5 ppm (13 mg/cu m) 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. 371

11.2.6 NIOSH Recommendations

Recommended Exposure Limit: 10 Hour Time-Weighted Average: 2 ppm (5 mg/cu m).
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
Recommended Exposure Limit: 15 Minute Short-Term Exposure Limit: 5 ppm (13 mg/cu m).
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg

11.3 First Aid Measures

Inhalation First Aid
Fresh air, rest. Artificial respiration may be needed. Refer for medical attention.
Skin First Aid
ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. Refer for medical attention .
Eye First Aid
Rinse with plenty of water for several minutes (remove contact lenses if easily possible). Refer for medical attention.

11.3.1 First Aid

Note: Persons with asthma, subnormal pulmonary function, or cardiovascular disease are at greater risk.

Signs and Symptoms of Acute Sulfur Dioxide Exposure: Sulfur dioxide may irritate the eyes and respiratory tract. Signs and symptoms of acute exposure to sulfur dioxide may be severe and include coughing, choking, dyspnea (shortness of breath), sneezing, wheezing, and chest discomfort. Upper airway edema (swelling) or obstruction, bronchoconstriction, pneumonia, pulmonary edema, and respiratory paralysis may occur. Fatigue may be noted. Gastrointestinal effects may include nausea, vomiting, and abdominal pain. Cyanosis (blue tint to skin and mucous membranes) may be noted following exposure to sulfur dioxide.

Emergency Life-Support Procedures: Acute exposure to sulfur dioxide may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:

1. Move victims to fresh air. Emergency personnel should avoid self-exposure to sulfur dioxide.

2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.

3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

4. Transport to a health care facility.

Dermal/Eye Exposure:

1. Remove victims from exposure. Emergency personnel should avoid self- exposure to sulfur dioxide.

2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.

3. Remove contaminated clothing as soon as possible.

4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.

5. Wash exposed skin areas with soap and water.

6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

7. Transport to a health care facility.

Ingestion Exposure: No information is available. (EPA, 1998)

U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
ERG 2024, Guide 125 (Sulfur dioxide)

General First Aid:

· Call 911 or emergency medical service.

· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.

· Move victim to fresh air if it can be done safely.

· Administer oxygen if breathing is difficult.

· If victim is not breathing:

-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingestedor inhaled the substance.

-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).

-- If no pulse detected or no respiratory medical device available, provide continuouscompressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.

· Remove and isolate contaminated clothing and shoes.

· For minor skin contact, avoid spreading material on unaffected skin.

· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.

· For severe burns, immediate medical attention is required.

· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.

· Keep victim calm and warm.

· Keep victim under observation.

· For further assistance, contact your local Poison Control Center.

· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.

Specific First Aid:

· In case of contact with liquefied gas, only medical personnel should attempt thawing frosted parts.

· In case of skin contact with hydrogen fluoride, anhydrous (UN1052), if calcium gluconate gel is available, rinse 5 minutes, then apply gel. Otherwise, continue rinsing until medical treatment is available.

In Canada, an Emergency Response Assistance Plan (ERAP) may be required for this product. Please consult the shipping paper and/or the "ERAP" section.

(See general first aid procedures)

Eye: Frostbite - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible.

Skin: Frostbite - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.

Breathing: Respiratory support

11.4 Fire Fighting

Wear self-contained breathing apparatus and full protective clothing. Move container from fire area. Stay away from ends of tanks. Cool containers that are exposed to flames with water from the side until well after the fire is out. Isolate area until gas has dispersed. Keep unnecessary people away.

Not flammable. Extinguish fires with dry chemical, carbon dioxide, water spray, fog or foam. (EPA, 1998)

U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
In case of fire in the surroundings, use appropriate extinguishing media. In case of fire: keep cylinder cool by spraying with water. NO direct contact with water. Combat fire from a sheltered position.

11.4.1 Fire Fighting Procedures

Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide. ...Wear self-contained breathing apparatus for firefighting if necessary.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html
Use water spray to keep fire-exposed containers cool. Extinguish fire using agent suitable for surrounding fire. /Sulfur dioxide, liquefied/
National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 49-140

11.4.2 Firefighting Hazards

Sulfur oxides
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html

11.5 Accidental Release Measures

Public Safety: ERG 2024, Guide 125 (Sulfur dioxide)

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Keep unauthorized personnel away.

· Stay upwind, uphill and/or upstream.

· Many gases are heavier than air and will spread along the ground and collect in low or confined areas (sewers, basements, tanks, etc.).

· Ventilate closed spaces before entering, but only if properly trained and equipped.

Spill or Leak: ERG 2024, Guide 125 (Sulfur dioxide)

· Do not touch or walk through spilled material.

· Stop leak if you can do it without risk.

· If possible, turn leaking containers so that gas escapes rather than liquid.

· Prevent entry into waterways, sewers, basements or confined areas.

· Do not direct water at spill or source of leak.

· Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material.

· Isolate area until gas has dispersed.

11.5.1 Isolation and Evacuation

Excerpt from ERG Guide 125 [Gases - Toxic and/or Corrosive]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

SPILL: See ERG Tables 1 and 3 - Initial Isolation and Protective Action Distances on the UN/NA 1079 datasheet.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. (ERG, 2024)

Evacuation: ERG 2024, Guide 125 (Sulfur dioxide)

Immediate precautionary measure

· Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

Spill

· For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.

· For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind direction, as necessary.

Fire

· If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions.

Isolation

Small spill:

- ISOLATE in all directions: 100 m (300 ft)

Large spill:

- ISOLATE in all Directions:

-- Rail tank car: 1000 m (3000 ft)

-- Highway tank truck or trailer: 1000 m (3000 ft)

-- Multiple ton cylinders: 500 m (1500 ft)

-- Multiple small cylinders or single ton cylinder: 200 m (600 ft)

Protection

Small spill:

- PROTECT people from downwind during DAY time: 0.6 km (0.4 mi)

- PROTECT people from downwind during NIGHT time: 2.6 km (1.6 mi)

Large spill:

- PROTECT people from downwind during DAY time:

-- Rail tank car:

- - - Low wind (< 6 mph (<10 km/h)): 11.0+ km (7.0+ mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 11.0+ km (7.0+ mi)

- - - High wind (> 12 mph (>20 km/h)): 6.9 km (4.3 mi)

-- Highway tank truck or trailer:

- - - Low wind (< 6 mph (<10 km/h)): 11.0+ km (7.0+ mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 6.0 km (3.8 mi)

- - - High wind (> 12 mph (>20 km/h)): 5.0 km (3.3 mi)

-- Multiple ton cylinders:

- - - Low wind (< 6 mph (<10 km/h)): 5.2 km (3.3 mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 2.2 km (1.4 mi)

- - - High wind (> 12 mph (>20 km/h)): 1.7 km (1.1 mi)

-- Multiple small cylinders or single ton cylinder:

- - - Low wind (< 6 mph (<10 km/h)): 3.1 km (1.9 mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 1.5 km (0.9 mi)

- - - High wind (> 12 mph (>20 km/h)): 1.1000000000000001 km (0.7 mi)

Large spill:

- PROTECT people from downwind during NIGHT time:

-- Rail tank car:

- - - Low wind (< 6 mph (<10 km/h)): 11.0+ km (7.0+ mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 11.0+ km (7.0+ mi)

- - - High wind (> 12 mph (>20 km/h)): 9.6 km (6.0 mi)

-- Highway tank truck or trailer:

- - - Low wind (< 6 mph (<10 km/h)): 11.0+ km (7.0+ mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 7.9 km (5.1 mi)

- - - High wind (> 12 mph (>20 km/h)): 6.0 km (3.9 mi)

-- Multiple ton cylinders:

- - - Low wind (< 6 mph (<10 km/h)): 7.4 km (4.3 mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 4.0 km (2.5 mi)

- - - High wind (> 12 mph (>20 km/h)): 2.7 km (1.7 mi)

-- Multiple small cylinders or single ton cylinder:

- - - Low wind (< 6 mph (<10 km/h)): 5.6 km (3.5 mi)

- - - Moderate wind (6-12 mph (10-20 km/h)): 2.4 km (1.5 mi)

- - - High wind (> 12 mph (>20 km/h)): 1.5 km (0.9 mi)

11.5.2 Spillage Disposal

Evacuate danger area! Consult an expert! Personal protection: complete protective clothing including self-contained breathing apparatus. Ventilation. NEVER direct water jet on liquid.

11.5.3 Cleanup Methods

1. Ventilate area of spill or leak to disperse gas. 2. If in gaseous form, stop flow of gas. If source of leak is cylinder and leak cannot be stopped in place, remove leaking cylinder to safe place in open air, and repair the leak or allow ... to empty. 3. If in liq form, allow to vaporize.
Mackison, F. W., R. S. Stricoff, and L. J. Partridge, Jr. (eds.). NIOSH/OSHA - Occupational Health Guidelines for Chemical Hazards. DHHS(NIOSH) Publication No. 81-123 (3 VOLS). Washington, DC: U.S. Government Printing Office, Jan. 1981., p. 3
Approach release from upwind. Stop or control the leak, if this can be done without undue risk. Use water spray to cool and disperse vapors and protect personnel. Control runoff and isolate discharged material for proper disposal. Releases may require isolation or evacuation. /Sulfur dioxide, liquefied/
National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 49-140
ACCIDENTAL RELEASE MEASURES; Personal precautions, protective equipment and emergency procedures: Wear respiratory protection. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Methods and materials for containment and cleaning up: Clean up promptly by sweeping or vacuum.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html

11.5.4 Disposal Methods

SRP: 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 air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.
Product: Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material. Contaminated packaging: Dispose of as unused product.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html
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.

11.5.5 Preventive Measures

ACCIDENTAL RELEASE MEASURES; Personal precautions, protective equipment and emergency procedures: Wear respiratory protection. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html
Avoid contact with skin and eyes. Avoid inhalation of vapor or mist.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html
Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html
Avoid contact with skin, eyes and clothing. Wash hands before breaks and immediately after handling the product.
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html
For more Preventive Measures (Complete) data for Sulfur dioxide (9 total), please visit the HSDB record page.

11.6 Handling and Storage

11.6.1 Nonfire Spill Response

Excerpt from ERG Guide 125 [Gases - Toxic and/or Corrosive]:

Do not touch or walk through spilled material. Stop leak if you can do it without risk. If possible, turn leaking containers so that gas escapes rather than liquid. Prevent entry into waterways, sewers, basements or confined areas. Do not direct water at spill or source of leak. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Isolate area until gas has dispersed. (ERG, 2024)

11.6.2 Safe Storage

Ventilation along the floor. Dry.

11.6.3 Storage Conditions

Storage temp: less than 130 °F
U.S. Coast Guard, Department of Transportation. CHRIS - Hazardous Chemical Data. Volume II. Washington, D.C.: U.S. Government Printing Office, 1984-5.
Compressed gas cylinders containing sulfur dioxide should be stored in accordance with 29 CFR 1910.101.
Mackison, F. W., R. S. Stricoff, and L. J. Partridge, Jr. (eds.). NIOSH/OSHA - Occupational Health Guidelines for Chemical Hazards. DHHS(NIOSH) Publication No. 81-123 (3 VOLS). Washington, DC: U.S. Government Printing Office, Jan. 1981., p. 2
Store in a cool, dry, well-ventilated location. Outside or detached storage is preferred. Isolate from oxidizing materials and alkalies. /Sulfur dioxide, liquefied/
National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 49-140
Keep container tightly closed in a dry and well-ventilated place. Contents under pressure. Storage class (TRGS 510): Gases
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html

11.7 Exposure Control and Personal Protection

Protective Clothing: ERG 2024, Guide 125 (Sulfur dioxide)

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Wear chemical protective clothing that is specifically recommended by the manufacturer when there is NO RISK OF FIRE.

· Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.

Exposure Summary
TIH (Toxic Inhalation Hazard) - Term used to describe gases and volatile liquids that are toxic when inhaled. Some are TIH materials themselves, e.g., chlorine, and some release TIH gases when spilled in water, e.g., chlorosilanes. [ERG 2016].
RD50 (Exposure concentration producing a 50% respiratory rate decrease)
117.0 [ppm]
Maximum Allowable Concentration (MAK)
1.0 [ppm]

11.7.2 Permissible Exposure Limit (PEL)

5.0 [ppm]
PEL-TWA (8-Hour Time Weighted Average)
5 ppm (13 mg/m³)
TWA 5 ppm (13 mg/m3) See Appendix G

11.7.3 Immediately Dangerous to Life or Health (IDLH)

100 ppm (NIOSH, 2024)

100.0 [ppm]

Excerpts from Documentation for IDLHs: The maximum concentration for exposures of 0.5 to 1 hour is considered to be 50 to 100 ppm [Henderson and Haggard 1943]. It has been reported that 400 to 500 ppm is considered dangerous for even short periods of exposure [Henderson and Haggard 1943].

100 ppm
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg

100 ppm

See: 7446095

11.7.4 Threshold Limit Values (TLV)

TLV-STEL
0.25 [ppm]
15 min Short Term Exposure Limit (STEL): 0.25 ppm.
American Conference of Governmental Industrial Hygienists TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati, OH 2017, p. 55
A4; Not classifiable as a human carcinogen.
American Conference of Governmental Industrial Hygienists TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati, OH 2017, p. 55
0.25 ppm as STEL; A4 (not classifiable as a human carcinogen).
TLV-STEL (Short Term Exposure Limit)
0.25 ppm [2008]

11.7.5 Occupational Exposure Limits (OEL)

EU-OEL
1.3 mg/m
MAK (Maximale Arbeitsplatz Konzentration)
2.7 mg/m

11.7.6 Emergency Response Planning Guidelines

Emergency Response: ERG 2024, Guide 125 (Sulfur dioxide)

Small Fire

· Dry chemical or CO2.

Large Fire

· Water spray, fog or regular foam.

· If it can be done safely, move undamaged containers away from the area around the fire.

· Do not get water inside containers.

· Damaged cylinders should be handled only by specialists.

Fire Involving Tanks

· Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.

· Cool containers with flooding quantities of water until well after fire is out.

· Do not direct water at source of leak or safety devices; icing may occur.

· Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.

· ALWAYS stay away from tanks in direct contact with flames.

ERPG-1: 0.3 ppm - one hour exposure limit: 1 = mild transient health effects or objectionable odor [AIHA]

ERPG-2: 3 ppm - one hour exposure limit: 2 = impaired ability to take protective action [AIHA]

ERPG-3: 25 ppm - one hour exposure limit: 3 = life threatening health effects [AIHA]

11.7.7 Other Standards Regulations and Guidelines

Action level (8 hr): 1 ppm
Braker W et al; Effects of Exposure to Toxic Gases-First Aid and Medical Treatment, Matheson Gas Products, Lyndhurst, NJ (1977) as cited in Environment Canada; Tech Info for Problem Spills: Sulfur dioxide (Draft) p.75 (1985)
National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75 parts per billion (ppb, which is 1 part in 1,000,000,000), measured in the ambient air as sulfur dioxide (SO2). (b) The 1-hour primary standard is met at an ambient air quality monitoring site when the three-year average of the annual (99th percentile) of the daily maximum 1-hour average concentrations is less than or equal to 75 ppb, as determined in accordance with appendix T of this part. (c) The level of the standard shall be measured by a reference method based on appendix A or A-1 of this part, or by a Federal Equivalent Method (FEM) designated in accordance with part 53 of this chapter.
40 CFR 50.17 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of April 18, 2018: https://www.ecfr.gov
National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). (a) The level of the 3-hour standard is 0.5 parts per million (ppm), not to be exceeded more than once per calendar year. The 3-hour averages shall be determined from successive nonoverlapping 3-hour blocks starting at midnight each calendar day and shall be rounded to 1 decimal place (fractional parts equal to or greater than 0.05 ppm shall be rounded up). (b) Sulfur oxides shall be measured in the ambient air as sulfur dioxide by the reference method described in appendix A of this part or by an equivalent method designated in accordance with part 53 of this chapter. (c) To demonstrate attainment, the second-highest 3-hour average must be based upon hourly data that are at least 75 percent complete in each calendar quarter. A 3-hour block average shall be considered valid only if all three hourly averages for the 3-hour period are available. If only one or two hourly averages are available, but the 3-hour average would exceed the level of the standard when zeros are substituted for the missing values, subject to the rounding rule of paragraph (a) of this section, then this shall be considered a valid 3-hour average. In all cases, the 3-hour block average shall be computed as the sum of the hourly averages divided by 3.
40 CFR 50.5 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of April 18, 2018: https://www.ecfr.gov
Emergency exposure limits: 150 ppm (5 min); 75 ppm (15 min); 50 ppm (30 min); 25 ppm (60 min)
Nat'l Research Council Canada; Effects of Sulfur dioxide in the Canadian Environ p.175 (1977) NRCC No. 15015
Emergency Response Planning Guidlines (ERPGs) for sulfur dioxide:
ERPG / LEL
ERPG-1: The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing more than mild, transient adverse health effects or without perceiving a clearly defined objectionable odor.
Airborne Concentration
0.3 ppm
Notations
Odor should be detectable near ERPG-1.
ERPG / LEL
ERPG-2: The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair an individual's ability to take protective action.
Airborne Concentration
3 ppm
ERPG / LEL
ERPG-3: The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing life-threatening health effects.
Airborne Concentration
25 ppm
ERPG / LEL
LEL (Lower Explosive Limit): The minimum concentration in air of a flammable gas or vapor at which ignition can occur.
Airborne Concentration
None
2015 Emergency Response Planning Guidelines (ERPG) & Workplace Exposure Level (WEEL). American Industrial Hygiene Association, Falls Church, VA 2015, p. 29

11.7.8 Inhalation Risk

A harmful concentration of this gas in the air will be reached very quickly on loss of containment.

11.7.9 Effects of Short Term Exposure

Rapid evaporation of the liquid may cause frostbite. The substance is irritating to the eyes and respiratory tract. Inhalation may cause asthma-like reactions. The substance may cause effects on the respiratory tract. This may result in asthma-like reactions, reflex spasm of the larynx and respiratory arrest. The effects may be delayed. Medical observation is indicated.

11.7.10 Effects of Long Term Exposure

Repeated or prolonged inhalation may cause asthma.

11.7.11 Allowable Tolerances

A tolerance is established as follows for sulfite residues of the fungicide sulfur dioxide (determined as (SO2)) in or on the following raw agricultural commodity(ies): grapes, postharvest: 10.0 ppm.
40 CFR 180.444 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov
Time-limited tolerances specified in the following table are established for residues of sulfur dioxide, including its metabolites and degradates in or on the specified agricultural commodities, resulting from use of the pesticide pursuant to FFIFRA section 18 emergency exemptions. Compliance with the tolerance levels specified below is to be determined by measuring only sulfur dioxide (SO2). The tolerances expire on the date specified in the table. Commodity: fig, 10 ppm, expiration/revocation date: 12/31/14.
40 CFR 180.444 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov

11.7.12 Personal Protective Equipment (PPE)

Excerpt from NIOSH Pocket Guide for Sulfur dioxide:

Skin: FROSTBITE - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.

Eyes: FROSTBITE - Wear appropriate eye protection to prevent eye contact with the liquid that could result in burns or tissue damage from frostbite.

Wash skin: No recommendation is made specifying the need for washing the substance from the skin (either immediately or at the end of the work shift).

Remove: WHEN WET OR CONTAMINATED (LIQUID) - If this chemical is in liquid form, work clothing that becomes wet or significantly contaminated should be removed and replaced.

Change: No recommendation is made specifying the need for the worker to change clothing after the workshift.

Provide: FROSTBITE WASH - Quick drench facilities and/or eyewash fountains should be provided within the immediate work area for emergency use where there is any possibility of exposure to liquids that are extremely cold or rapidly evaporating. (NIOSH, 2024)

Respirator Recommendations: Up to 20 ppm
Assigned Protection Factor (APF)
APF = 10
Respirator Recommendation
Any chemical cartridge respirator with cartridge(s) providing protection against the compound of concern. Substance reported to cause eye irritation or damage; may require eye protection.
Assigned Protection Factor (APF)
APF = 10
Respirator Recommendation
Any supplied-air respirator. Substance reported to cause eye irritation or damage; may require eye protection.
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
Respirator Recommendations: Up to 50 ppm
Assigned Protection Factor (APF)
APF = 25
Respirator Recommendation
Any supplied-air respirator operated in a continuous-flow mode. Substance reported to cause eye irritation or damage; may require eye protection.
Assigned Protection Factor (APF)
APF = 25
Respirator Recommendation
Any powered, air-purifying respirator with cartridge(s) providing protection against the compound of concern. Substance reported to cause eye irritation or damage; may require eye protection.
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
Respirator Recommendations: Up to 100 ppm
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendation
Any chemical cartridge respirator with a full facepiece and cartridge(s) providing protection against the compound of concern.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendation
Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendation
Any powered, air-purifying respirator with a tight-fitting facepiece and cartridge(s) providing protection against the compound of concern. Substance reported to cause eye irritation or damage; may require eye protection.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendation
Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode. Substance reported to cause eye irritation or damage; may require eye protection.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendation
Any self-contained breathing apparatus with a full facepiece.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendation
Any supplied-air respirator with a full facepiece.
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
Respirator Recommendations: Emergency or planned entry into unknown concentrations or IDLH conditions:
Assigned Protection Factor (APF)
APF = 10,000
Respirator Recommendation
Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode.
Assigned Protection Factor (APF)
APF = 10,000
Respirator Recommendation
Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus.
NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
For more Personal Protective Equipment (PPE) (Complete) data for Sulfur dioxide (12 total), please visit the HSDB record page.

(See personal protection and sanitation codes)

Skin: Frostbite - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.

Eyes: Frostbite - Wear appropriate eye protection to prevent eye contact with the liquid that could result in burns or tissue damage from frostbite.

Wash skin: No recommendation

Remove: When wet or contaminated (liquid)

Change: No recommendation

Provide: Frostbite wash - Quick drench facilities and/or eyewash fountains should be provided within the immediate work area for emergency use where there is any possibility of exposure to liquids that are extremely cold or rapidly evaporating.

11.7.13 Respirator Recommendations

NIOSH

Up to 20 ppm:

(APF = 10) Any chemical cartridge respirator with cartridge(s) providing protection against the compound of concern*

(APF = 10) Any supplied-air respirator*

Up to 50 ppm:

(APF = 25) Any supplied-air respirator operated in a continuous-flow mode*

(APF = 25) Any powered, air-purifying respirator with cartridge(s) providing protection against the compound of concern*

Up to 100 ppm:

(APF = 50) Any chemical cartridge respirator with a full facepiece and cartridge(s) providing protection against the compound of concern

(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern

(APF = 50) Any powered, air-purifying respirator with a tight-fitting facepiece and cartridge(s) providing protection against the compound of concern*

(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode*

(APF = 50) Any self-contained breathing apparatus with a full facepiece

(APF = 50) Any supplied-air respirator with a full facepiece

Emergency or planned entry into unknown concentrations or IDLH conditions:

(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode

(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus

Escape:

(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern

Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

11.7.14 Preventions

Exposure Prevention
STRICT HYGIENE! IN ALL CASES CONSULT A DOCTOR!
Inhalation Prevention
Use ventilation, local exhaust or breathing protection.
Skin Prevention
Cold-insulating gloves.
Eye Prevention
Wear safety goggles, face shield or eye protection in combination with breathing protection.

11.8 Stability and Reactivity

11.8.1 Air and Water Reactions

Dissolves in water to form sulfurous acid, a corrosive liquid. Moist sulfur dioxide is very corrosive due to the slow formation of sulfuric acid [Handling Chemicals Safely 1980 p. 876].

11.8.2 Reactive Group

Acids, Strong Non-oxidizing

Reducing Agents, Weak

11.8.3 Reactivity Alerts

Water-Reactive

11.8.4 Reactivity Profile

SULFUR DIOXIDE is acidic. Reacts exothermically with bases such as amines, amides, metal oxides, and hydroxides. Frequently used as a reducing agent although it is not a powerful one. Acts as a reducing bleach to decolorize many materials. Can act as an oxidizing agent. Supports combustion of powdered aluminum [Mellor 5:209-212 1946-47]. Reacts explosively with fluorine [Mellor 2:1 1946-47]. Supports burning of manganese [Mellor 12:187 1946-47]. Readily liquefied by compression. Contact between the liquid and water may result in vigorous or violent boiling and extremely rapid vaporization. If the water is hot an explosion may occur. Pressures may build to dangerous levels if the liquid contacts water in a closed container [Handling Chemicals Safely 1980]. Supports incandescent combustion of monocesium acetylide, monopotassium acetylide, cesium oxide, iron(II) oxide, tin oxide, and lead oxide [Mellor]. Ethylene oxide and SO2 can react violently in pyridine solution with pressurization if ethylene oxide is in excess (Nolan, 1983, Case History 51).

11.8.5 Hazardous Reactivities and Incompatibilities

Will react with water or steam to produce toxic and corrosive fumes.
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 3331
Monocesium or monopotassium acetylides, and the ammoniate of monolithium acetylide, all ignite and incandesce in unheated sulfur dioxide. The dimetal derivatives including sodium acetylide appear to be less reactive, needing heat before ignition occurs.
Bretherick, L. Handbook of Reactive Chemical Hazards. 4th ed. Boston, MA: Butterworth-Heinemann Ltd., 1990, p. 1415
Cesium monoxide, iron(II) oxide, tin oxide, and lead(IV) oxide all ignite and incandesce on heating in /sulfur dioxide/ gas. Finely divided (pyrophoric) chromium incandesces in sulfur dioxide, while pyrophoric manganese burns ... on heating in gas. Molten sodium reacts violently with dry gas or liquid, while moist gas reacts as vigorously as water with cold sodium.
Bretherick, L. Handbook of Reactive Chemical Hazards. 4th ed. Boston, MA: Butterworth-Heinemann Ltd., 1990, p. 1415
Heated oxide /barium peroxide/ attains incandescence in a rapid stream of ... sulfur dioxide.
Bretherick, L. Handbook of Reactive Chemical Hazards. 4th ed. Boston, MA: Butterworth-Heinemann Ltd., 1990, p. 84
For more Hazardous Reactivities and Incompatibilities (Complete) data for Sulfur dioxide (18 total), please visit the HSDB record page.

11.9 Transport Information

11.9.1 DOT Emergency Guidelines

If ... THERE IS NO FIRE, go directly to the Table of Initial Isolation and Protective Action Distances /(see table below)/ ... to obtain initial isolation and protective action distances. IF THERE IS A FIRE, or IF A FIRE IS INVOLVED, go directly to the appropriate guide /(see guide(s) below)/ and use the evacuation information shown under PUBLIC SAFETY.

Table: Table of Initial Isolation and Protective Action Distances for Sulfur dioxide; Sulphur dioxide ID: 1079

Small Spills (from a small package or small leak from a large package)
First ISOLATE in all Directions
Small Spills (from a small package or small leak from a large package)
Then PROTECT persons Downwind during DAY:
Small Spills (from a small package or small leak from a large package)
Then PROTECT persons Downwind during NIGHT:
Large Spills (from a large package or small leak from a large package)
First ISOLATE in all Directions
Large Spills (from a large package or small leak from a large package)
Then PROTECT persons Downwind during DAY:
Large Spills (from a large package or small leak from a large package)
Then PROTECT persons Downwind during NIGHT:
Small Spills (from a small package or small leak from a large package)
100 m (300 ft)
Small Spills (from a small package or small leak from a large package)
0.7 km (0.4 mi)
Small Spills (from a small package or small leak from a large package)
2.2 km (1.4 mi)
Large Spills (from a large package or small leak from a large package)
Refer to table 3
Large Spills (from a large package or small leak from a large package)
Refer to table 3
Large Spills (from a large package or small leak from a large package)
Refer to table 3

U.S. Department of Transportation. 2016 Emergency Response Guidebook. Washington, D.C. 2016

If ... THERE IS NO FIRE, go directly to the Table of Initial Isolation and Protective Action Distances /(see table below)/ ... to obtain initial isolation and protective action distances. IF THERE IS A FIRE, or IF A FIRE IS INVOLVED, go directly to the appropriate guide /(see guide(s) below)/ and use the evacuation information shown under PUBLIC SAFETY.

Table: Table of Initial Isolation and Protective Action Distances For Different Quantities in Sulfur dioxide/Sulphur dioxide: Large Spills ID:1079

TRANSPORT CONTAINER
TRANSPORT CONTAINER
First ISOLATE in all Directions
First ISOLATE in all Directions
Then PROTECT persons downwind during
DAY
Then PROTECT persons downwind during
DAY
Then PROTECT persons downwind during
DAY
Then PROTECT persons downwind during
NIGHT
Then PROTECT persons downwind during
NIGHT
Then PROTECT persons downwind during
NIGHT
TRANSPORT CONTAINER
TRANSPORT CONTAINER
First ISOLATE in all Directions
First ISOLATE in all Directions
Then PROTECT persons downwind during
Low Wind (<6 mph= <10 km/h)
Then PROTECT persons downwind during
Moderate wind (6-12 mph = 10-20 km/hr)
Then PROTECT persons downwind during
High wind (>12 mph = >20 km/hr)
Then PROTECT persons downwind during
Low Wind (<6 mph= <10 km/h)
Then PROTECT persons downwind during
Moderate wind (6-12 mph = 10-20 km/hr)
Then PROTECT persons downwind during
High wind (>12 mph = >20 km/hr)
TRANSPORT CONTAINER
Rail tank car
First ISOLATE in all Directions
1000 m (3000 ft)
Then PROTECT persons downwind during
11+ km (7+ mi)
Then PROTECT persons downwind during
11+ km (7+ mi)
Then PROTECT persons downwind during
7.0 km (4.4 mi)
Then PROTECT persons downwind during
11+ km (7+ mi)
Then PROTECT persons downwind during
11+ km (7+ mi)
Then PROTECT persons downwind during
9.8 km (6.1 mi)
TRANSPORT CONTAINER
Highway tank truck or trailer
First ISOLATE in all Directions
1000 m (3000 ft)
Then PROTECT persons downwind during
11+ km (7+ mi)
Then PROTECT persons downwind during
5.8 km (3.6 mi)
Then PROTECT persons downwind during
5.0 km (3.1 mi)
Then PROTECT persons downwind during
11+ km (7+ mi)
Then PROTECT persons downwind during
8.0 km (5.0 mi)
Then PROTECT persons downwind during
6.1 km (3.8 mi)
TRANSPORT CONTAINER
Multiple ton cylinders
First ISOLATE in all Directions
500 m (1500 ft)
Then PROTECT persons downwind during
5.2 km (3.2 mi)
Then PROTECT persons downwind during
2.4 km (1.5 mi)
Then PROTECT persons downwind during
1.8 km (1.1 mi)
Then PROTECT persons downwind during
7.5 km (4.7 mi)
Then PROTECT persons downwind during
4.0 km (2.5 mi)
Then PROTECT persons downwind during
2.8 km (1.7 mi)
TRANSPORT CONTAINER
Multiple small cylinders or single ton cylinder
First ISOLATE in all Directions
200 m (600 ft)
Then PROTECT persons downwind during
3.1 km (1.9 mi)
Then PROTECT persons downwind during
1.5 km (0.9 mi)
Then PROTECT persons downwind during
1.1 km (0.7 mi)
Then PROTECT persons downwind during
5.6 km (3.5 mi)
Then PROTECT persons downwind during
2.4 km (1.5 mi)
Then PROTECT persons downwind during
1.5 km (0.9 mi)

U.S. Department of Transportation. 2016 Emergency Response Guidebook. Washington, D.C. 2016
/GUIDE 125 GASES - CORROSIVE/ Fire or Explosion: Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Some of these materials may react violently with water. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. . For UN1005: Anhydrous ammonia, at high concentrations in confined spaces, presents a flammability risk if a source of ignition is introduced
U.S. Department of Transportation. 2016 Emergency Response Guidebook. Washington, D.C. 2016
/GUIDE 125 GASES - CORROSIVE/ Health: TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Vapors are extremely irritating and corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.
U.S. Department of Transportation. 2016 Emergency Response Guidebook. Washington, D.C. 2016
For more DOT Emergency Guidelines (Complete) data for Sulfur dioxide (10 total), please visit the HSDB record page.

11.9.2 DOT ID and Guide

11.9.3 Shipping Name / Number DOT/UN/NA/IMO

UN 1079; Sulfur dioxide
IMO 2.3; Sulfur dioxide

11.9.4 Standard Transportation Number

49 042 90; Sulfur dioxide

11.9.5 Shipment Methods and Regulations

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 (USDOT); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 9, 2017: 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. Sulfur dioxide is included on the dangerous goods list.
International Air Transport Association. Dangerous Goods Regulations. 57th Edition. Montreal, Quebec Canada. 2016., p. 321
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. Sulfur dioxide is included on the dangerous goods list.
International Maritime Organization. IMDG Code. International Maritime Dangerous Goods Code Volume 2 2014, p. 46

11.9.6 DOT Label

Poison Gas Corrosive

11.9.7 Packaging and Labelling

Note: 5

11.9.8 EC Classification

Symbol: T; R: 23-34; S: (1/2)-9-26-36/37/39-45

11.9.9 UN Classification

UN Hazard Class: 2.3; UN Subsidiary Risks: 8

11.10 Regulatory Information

The Australian Inventory of Industrial Chemicals
Chemical: Sulfur dioxide
California Safe Cosmetics Program (CSCP) Reportable Ingredient

Hazard Traits - Developmental Toxicity; Respiratory Toxicity

Authoritative List - OEHHA RELs; Prop 65

Report - regardless of intended function of ingredient in the product

REACH Registered Substance
New Zealand EPA Inventory of Chemical Status
Sulphur dioxide: HSNO Approval: HSR001068 Approved with controls

11.10.1 DHS Chemicals of Interest (COI)

Chemicals of Interest(COI)
Sulfur dioxide (anhydrous)
Release: Minimum Concentration (%)
1
Release: Screening Threshold Quantities (in pounds)
5000
Theft: Minimum Concentration (%)
84
Theft: Screening Threshold Quantities (in pounds unless otherwise noted)
500
Security Issue: Release - Toxic
Toxic chemical that can be released at a facility.
Security Issue: Theft - WME
Weapons of Mass Effect chemical material that, if stolen or diverted, can be converted into weapons using simple chemistry, equipment, or techniques.

11.10.2 CERCLA Reportable Quantities

Releases of CERCLA hazardous substances are subject to the release reporting requirement of CERCLA section 103, codified at 40 CFR part 302, in addition to the requirements of 40 CFR part 355. Sulfur dioxide is an extremely hazardous substance (EHS) subject to reporting requirements when stored in amounts in excess of its threshold planning quantity (TPQ) of 500 lbs.
40 CFR 355 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov

11.10.3 FIFRA Requirements

A tolerance is established as follows for sulfite residues of the fungicide sulfur dioxide (determined as (SO2)) in or on the following raw agricultural commodity(ies): grapes, postharvest: 10.0 ppm.
40 CFR 180.444 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov
Time-limited tolerances specified in the following table are established for residues of sulfur dioxide, including its metabolites and degradates in or on the specified agricultural commodities, resulting from use of the pesticide pursuant to FFIFRA section 18 emergency exemptions. Compliance with the tolerance levels specified below is to be determined by measuring only sulfur dioxide (SO2). The tolerances expire on the date specified in the table. Commodity: fig, 10 ppm, expiration/revocation date: 12/31/14.
40 CFR 180.444 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov
The Agency is proposing no changes in the level or definition of the existing tolerance. Therefore, the current tolerance established at 40 CFR 180.444 for sulfur dioxide residues (expressed as sulfite) in grapes is now considered reassessed under section 408(q) of the FFDCA.
USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Inorganic Sulfites p.12 (May 2007). Available from, as of October 11, 2017: 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 continued use. Under this pesticide reregistration program, EPA examines newer health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether the use of the pesticide does not pose unreasonable risk in accordance to newer saftey standards, such as those described in the Food Quality Protection Act of 1996. Pesticides for which EPA had not issued Registration Standards prior to the effective date of FIFRA '88 were divided into three lists based upon their potential for human exposure and other factors, with List B containing pesticides of greater concern than those on List C, and with List C containing pesticides of greater concern than those on List D. Sulfur dioxide is found on List D. Case No: 4056; Pesticide type: fungicide; 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): Sulfur dioxide; Data Call-in (DCI) Date(s): 09/30/93, 10/13/95; AI Status: The producers of the pesticide has 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.320 (Spring, 1998) EPA 738-R-98-002

11.10.4 FDA Requirements

Sulfur dioxide ... is generally recognized as safe when used in accordance with good manufacturing practice, except that it is not used in meats; in food recognized as a source of vitamin B1; on fruits or vegetables intended to be served raw to consumers or sold raw to consumers, or to be presented to consumers as fresh.
21 CFR 182.3862 (USFDA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov
Sulfur dioxide ... is generally recognized as safe when used in accordance with good manufacturing or feeding practice, except that it is not used in meats or in food recognized as source of vitamin B1.
21 CFR 582.3862 (USFDA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 2, 2017: https://www.ecfr.gov

11.11 Other Safety Information

Chemical Assessment
IMAP assessments - Sulfur dioxide: Human health tier II assessment

11.11.1 Other Hazardous Reactions

Incompatible materials: Strong reducing agents, Zinc, Strong oxidizing agents
Sigma-Aldrich; Safety Data Sheet for Sulfur Dioxide. Product Number: 295698, Version 3.7 (Revision Date 03/03/2015). Available from, as of August 31, 2017: https://www.sigmaaldrich.com/safety-center.html

11.11.2 History and Incidents

Smog (SO2): Meuse Valley, Belgium (1930) 64 deaths /from table/
Goldfrank, L.R., Goldfrank's Toxicologic Emergencies 10th Ed. 2015., McGraw-Hill, New York, N.Y., p. 16
Smog (SO2): Donora, Pennsylvania (1948) 20 deaths, thousands ill. /from table/
Goldfrank, L.R., Goldfrank's Toxicologic Emergencies 10th Ed. 2015., McGraw-Hill, New York, N.Y., p. 16
Smog (SO2): London, England (1952) 4000 deaths attributed to the fog and smog. /from table/
Goldfrank, L.R., Goldfrank's Toxicologic Emergencies 10th Ed. 2015., McGraw-Hill, New York, N.Y., p. 16
Smog (SO2): London, England (1873) 268 deaths from bronchitis. /from table/
Goldfrank, L.R., Goldfrank's Toxicologic Emergencies 10th Ed. 2015., McGraw-Hill, New York, N.Y., p. 16
Increased ambient SO2 concentrations have been linked epidemiologically with both acute morbidity and mortality. in December 1952, approximately 4,000 excess deaths and substantial morbidity were attributed to an air pollution episode in which SO2 averaged 0.95 ppm and particulate matter (measured as British Smoke) was measured at concentrations up to approximately 4 mg per cubic meter (24-hour average). In this and several other episodes, the excess illness and deaths clearly were associated with the air pollution mixture, although the relative etiologic roles of SO2, particulate matter, aerosol acidity, or other unmeasured pollutants have not been delineated clearly.
Sullivan, J.B., Krieger G.R. (eds). Clinical Environmental Health and Toxic Exposures. Second edition. Lippincott Williams and Wilkins, Philadelphia, Pennsylvania 1999., p. 826

11.11.3 Special Reports

USEPA/Office of Pesticide Programs; Reregistration Eligibility Decision Document - Inorganic Sulfites (May 2007). 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.
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Occupational Exposures to Mists and Vapours from Strong Inorganic Acids; and Other Industrial Chemicalsv 54 (1992). IARC Monographs provide critical reviews of data on carcinogenicity for agents to which humans are known to be exposed and on specific exposure situations[Available from, as of November 21, 2017: http://monographs.iarc.fr/ENG/Monographs/vol54/index.php]

12 Toxicity

12.1 Toxicological Information

12.1.1 Toxicity Summary

IDENTIFICATION AND USE: Sulfur dioxide (SO2) is a colorless gas or liquid with a strong suffocating odor. SO2 is used as a fungicide and preservative for grapes. It is also used for the manufacture of corn syrups and molasses, in the manufacture of wine to destroy bacteria, mold, and unwanted yeasts, and for sterilization, and prevents the formation of nitrosamines in beer. SO2 is used to manufacture hydrosulfites, to bleach wood pulp and paper, to process, disinfect, and bleach food, for waste and water treatment, in metal and ore refining, and in oil refining. HUMAN STUDIES: Exposures of less than an hour to SO2 at levels above 10 ppm in air are irritating to the nose and throat, sometimes causing a choking sensation followed by nasal discharge, sneezing, coughing, and increased mucous secretion. Severe injuries of human eyes by sulfur dioxide have been produced only by liquified form. The minimum lethal human exposure is an airborne concentration of 400 ppm for 1 minute. The odor or taste is noticeable at airborne concentrations of 3 to 5 ppm, throat and conjunctival irritation and lacrimation start at 8 to 12 ppm, and symptoms become severe at 50 ppm. Other reported minimum lethal concentrations of sulfur dioxide include 3000 ppm for 5 minutes and 1000 ppm for 10 minutes. Elderly patients with asthma may be more sensitive. A 76-year-old woman with asthma died following inhalation exposure to approximately 150 ppm over a period of minutes. The frequencies of chromosomal aberrations and sister-chromatid exchange (SCE) in peripheral blood lymphocytes of 40 workers chronically exposed to SO2 at a sulfuric acid factory were studied. It was shown that the mean frequency of chromosomal aberrations and the mean frequency of lymphocytes with chromosomal aberrations of the SO2-exposed workers were both higher than controls. In human lymphocytes SO2 caused significant increases in the frequency of sister chromatid exchange and micronuclei and also induced mitotic delays and decreased mitotic index and replication index. The potential risk of low birth-weight baby might be higher in elder women exposed to SO2 during pregnancy. ANIMAL STUDIES: SO2 has been found to be endogenously generated from metabolism of sulfur-containing amino acids in mammals through transamination by aspartate aminotransferase. SO2 has physiological effects on the cardiovascular system, including vasorelaxation and cardiac function regulation. Eye irritation occurs at 6 ppm/4 hr in rabbits. After a 120-hr exposure to SO2 concentration of 1.1 ppm, guinea pigs showed proliferative interstitial pneumonia, bronchitis, and tracheitis and an increased histamine content in the lungs, while exposure to 0.06 ppm of SO2 for one month led to interstitial changes in the respiratory tract. In rats continuously exposed to SO2 for 5 months (0.7 ppm and 7.0 ppm), it increased the activity of serum cholinesterase and aspartate aminotransferase and caused morphological changes in the upper respiratory tract. Prolonged exposure of dogs to high concentrations of SO2 (200 ppm) causes a syndrome similar to human chronic bronchitis, involving chronic airway obstruction, airway inflammation, and symptoms of cough and mucus hypersecretion. In mice, fetal weight was reduced by 5% by exposure to SO2. Ossification of the sternebrae and occipital was retarded, but the incidence of malformations was not significantly increased. In rabbits, the incidence of a few minor skeletal variants was significantly increased in group exposed to SO2. SO2 increased the frequencies of chromosome aberrations and aberrant cells in mouse bone marrow in a dose-dependent manner. SO2 inhalation caused an increase of micronuclei frequencies in the polychromatic erythrocytes. SO2 caused significant, dose-dependent increases in DNA damage by inhalation exposure of mice. ECOTOXICITY STUDIES: SO2 was acutely toxic to fish. Green plants are extremely sensitive to atmospheric sulfur dioxide. Alfalfa, barley, cotton, and wheat can be injured at levels between 0.15 and 0.20 ppm, while potatoes, onions, and corn are far more resistant.

12.1.2 RAIS Toxicity Values

Inhalation Acute Reference Concentration (RfCa) (mg/m^3)
0.026200408997955
Inhalation Acute Reference Concentration Reference
ATSDR Final

12.1.3 NIOSH Toxicity Data

12.1.4 Evidence for Carcinogenicity

Evaluation: There is inadequate evidence for the carcinogenicity in humans of sulfur dioxide, sulfites, bisulfites and metabisulfites. There is limited evidence for the carcinogenicity in experimental animals of sulfur dioxide. There is inadequate evidence for the carcinogenicity in experimental animals of sulfites, bisulfites and metabisulfites. Overall evaluation: Sulfur dioxide, sulfites, bisulfites and metabisulfites are not classifiable as to their carcinogenicity to humans (Group 3).
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. 54 178 (1992)
A4; Not classifiable as a human carcinogen.
American Conference of Governmental Industrial Hygienists TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati, OH 2017, p. 55

12.1.5 Carcinogen Classification

IARC Carcinogenic Agent
Sulfur dioxide
IARC Carcinogenic Classes
Group 3: Not classifiable as to its carcinogenicity to humans
IARC Monographs
Volume 54: (1992) Occupational Exposures to Mists and Vapours from Strong Inorganic Acids; and Other Industrial Chemicals

12.1.6 Exposure Routes

The substance can be absorbed into the body by inhalation.
inhalation, skin and/or eye contact

12.1.7 Symptoms

Inhalation Exposure
Cough. Shortness of breath. Sore throat. Laboured breathing.
Skin Exposure
ON CONTACT WITH LIQUID: FROSTBITE.
Eye Exposure
Redness. Pain.
irritation eyes, nose, throat; rhinorrhea (discharge of thin nasal mucus); choking, cough; reflex bronchoconstriction; liquid: frostbite

12.1.8 Target Organs

Respiratory (From the Nose to the Lungs)
Eyes, skin, respiratory system

12.1.9 Adverse Effects

Chronic Bronchitis - Chronic bronchitis is persistent coughing and production of phlegm for at least 3 months out of the year for at least two successive years. (American Thoracic Society).

Toxic Pneumonitis - Inflammation of the lungs induced by inhalation of metal fumes or toxic gases and vapors.

Fibrogenic - Inducing tissue injury and fibrosis (scarring).

ACGIH Carcinogen - Not Classifiable.

12.1.10 Acute Effects

12.1.11 Toxicity Data

LC50 (rat) = 2,520 ppm/1H

12.1.12 Interactions

Cigarette smoking (CS) and air pollution can both alter autonomic cardiac function, yet little has been reported on their combined effect on cardiovascular dysfunction. Therefore, we assessed The potential effect of cigarette smoking (CS) on the association between sulfur dioxide (SO(2)) and heart rate variability (HRV) /was examined/ in community residents. ...Evidence /was found/ that SO(2) induced short but dramatic decreases in HRV indices, the standard deviation of the NN interval (SDNN), low frequency (LF), and high frequency (HF), in smokers compared with non-smokers. /Data/ suggest that CS influences the decrease in HRV directly caused by SO(2), and the effect in susceptible groups may be more serious.
Min, J-Y et al; Intl J Cardiol 133 (1): 119-21 (2009)
Wistar rats were exposed to intratracheally instilled with benzo(a)pyrene (B(a)P; 3 mg) or SO2 (20 ppm) inhalation alone or together. The mRNA of CYP1A1 and 1A2, c-fos, and c-jun and protein levels of c-fos and c-jun were analyzed in lungs ... and 7-ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities were detected. In lungs of rats exposed to SO2 alone, the gene transcription of CYP1A1 and 1A2, the EROD and MROD activities were decreased. Meanwhile, the mRNA and protein levels of c-jun and c-fos were increased significantly. Exposure to B(a)P alone induced CYP1A1, CYP1A2 mRNA levels, the protein levels of c-jun, and the EROD and MROD activities in lungs. However, exposure to B(a)P plus inhaled SO2 neither increased nor decreased CYP1A1/2 mRNA expressions, EROD, and MROD activities in lungs, versus exposure to B(a)P alone. Nevertheless, exposure to B(a)P plus inhaled SO2 increased the mRNA and protein levels of c-jun and c-fos in lungs compared with lungs exposed to SO2 alone. Accordingly, the SO2-induced decreases of CYP1A1/2 might not influence the metabolic activation of B(a)P. However, when B(a)P and SO2 were given in the combinations, one might postulate that a synergistic effect on the expressions of c-fos and c-jun between SO2 and B(a)P, which might be one of the possible mechanisms of combination effects between B(a)P and the air pollutants.
Qin G, Meng Z: Reg Toxicicol Pharmacol; 45 (1): 36-43 (2006)
The antioxidant effects of exogenous salicylic acid (SA) and vitamin C (Vit C) on the oxidative stress induced by 56 mg/cu m of sulfur dioxide (SO2) in mouse livers and brains were investigated. The exposure of SO2 caused significant elevation of thiobarbituric acid-reactive substance (TBARS) levels and reduction of enzyme activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in brain and liver, accompanied by a decrease in relative growth rate, when compared with controls. Application of moderate concentrations of SA and Vit C markedly reduced the SO2-induced elevation of TBARS levels, with 5.5 mg/kg SA or 200 mg/kg Vit C being most effective. In contrast to the decrease of TBARS levels, the levels of SOD, POD, and CAT in liver and brain were significantly increased in comparison with controls. The polyacrylamide gel electrophoresis (PAGE) of total liver proteins showed that the SO2 inhalation caused a 30-kD protein band disappearance compared with the control. However, the band remained unchanged in the samples treated with 5.5 and 8.25 mg/kg SA or 100, 200, and 400 mg/kg Vit C. Therefore, this protein band may serve as a marker for the damage induced by SO2 and an additional basis for drug screening and selection.
Zhao H et al; Inh Toxicol 20 (9): 865-71 (2008)
Aerosols that have produced ... potentiation of response to sulfur dioxide are soluble salts of such metals as manganese, ferrous iron, and vanadium. ... These aerosols potentiate response about three fold when present at concentration of 1 mg/cu m at 50% relative humidity.
Doull, J., C.D.Klassen, and M.D. Amdur (eds.). Casarett and Doull's Toxicology. 3rd ed., New York: Macmillan Co., Inc., 1986., p. 811
For more Interactions (Complete) data for Sulfur dioxide (20 total), please visit the HSDB record page.

12.1.13 Antidote and Emergency Treatment

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. /Sulfur and related compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3rd revised edition, Elsevier Mosby, St. Louis, MO 2007, p. 479
Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. 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 ... . 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 ... . Cover skin burns with dry sterile dressings after decontamination ... . /Sulfur and related compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3rd revised edition, Elsevier Mosby, St. Louis, MO 2007, p. 479
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. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasms ... . 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. Consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Sulfur and related compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3rd revised edition, Elsevier Mosby, St. Louis, MO 2007, p. 480

12.1.14 Medical Surveillance

Preplacement and annual medical examinations should be done whenever TWA exposures exceed 0.25 ppm (0.65 mg/cu m). These examinations should be directed toward complaints of mucous membrane irritation, cough and shortness of breath. They should ascertain that nasal passages are open. Persons with a history of asthma or with subnormal pulmonary function should be watched closely. Simple expiratory function tests should be a part of the examination. They are useful for several purposes: (a) determining whether or not a person is a suitable candidate for using respirators; (b) identifying "reactors", ie, persons who may be most susceptible to the effects of SO2. This can be done by comparing preshift and postshift tests; (c) when done periodically, they can be used to determine whether or not a person's expiratory functions are declining at a faster than normal rate. Such determinations are much more sensitive when pooled data from a number of individuals are used. The forced expiratory volume at 1 second and the maximum mid-expiratory flow rate appear to be the most useful of the simple pulmonary function tests.
OSHA; Public Hearing on Occupational Standard for Sulfur Dioxide: Statement of Edward Baier (NIOSH) (May 1977) PB 83-182485

12.1.15 Human Toxicity Excerpts

/HUMAN EXPOSURE STUDIES/ Twenty five healthy adults were tested and found to have increased airway resistance (determined in a body plethysmograph) at 5 ppm (13 mg/cu m) of sulfur dioxide and at higher levels when breathing normally for 10 min, but not at lower levels. After 25 deep breaths, as might occur in laborers doing hard physical work, the subjects had a statistically significant increase in airway resistance at 1 ppm and after 8 deep breaths at 3 ppm.
Lawther PG et al; Environ Res 10: 335 (1975)
/HUMAN EXPOSURE STUDIES/ In a study comprising a series of experiments over a period of 4 yr, a small increase in specific airway flow resistance (flow resistance corrected for lung volume) was seen in response to sulfur dioxide at 1 ppm, but only if the subjects took 25 maximal breaths of the gas starting from residual volume. The procedure was designed to increase dosage to the laryngotracheobronchial airways. In one subject, there was a threefold increase in specific airway flow resistance with this procedure. As expected, sulfur dioxide at 3 ppm elicited greater changes in function than did 1 ppm. The magnitudes of these changes were proportional to the numbers of deep breaths taken.
Ferris GB et al; Amer Rev Respir Dis 113: 475-85 (1976)
/HUMAN EXPOSURE STUDIES/ The effects of sulfur dioxide and ozone alone and in combinations /were studied/ on young normal subjects under conditions of light exercise. When breathed alone, 0.37 ppm of sulfur dioxide had no effect on any measurement of lung function; 0.37 ppm of ozone produced a just significant decline of ventilatory function at the end of a 2 hr exposure. However, when the two gases were present together in eight normal young subjects who were non-smokers, the maximal mid-expiratory flow rate dropped to 67% of its initial value at the end of 2 hr; the forced expiratory volume was 78% of its initial value, and the mid-expiratory flow rate (50% vital capacity) was only 54% of the initial value. A 2 hr exposure to 0.75 ppm of sulfur dioxide alone dropped the maximal mid-expiratory flow rate to 90% of its control value. /It was/ concluded that sulfur dioxide and ozone are exceedingly corrosive when present together, that "standard" must specify the presence or absence of the other, and that there is a growing incidence of the joint presence of the two pollutants in urban environments. /Air pollution/
Bates DV, Hazucha M; Paris Vol IV: 1977 (1974)
/HUMAN EXPOSURE STUDIES/ Bronchoalveolar lavage of 12 healthy, nonsmoking subjects 24 hr after exposure for 20 min to 4 or 8 ppm (10.5 or 21 mg/cu m) sulfur dioxide showed increased alveolar macrophage lysosomal activity; at the higher level, the numbers of macrophages and lymphocytes in the lavage fluid were increased. No effect on lung function was observed.
IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: https://monographs.iarc.fr/ENG/Classification/index.php, p. V54 167 (1992)
For more Human Toxicity Excerpts (Complete) data for Sulfur dioxide (79 total), please visit the HSDB record page.

12.1.16 Non-Human Toxicity Excerpts

/LABORATORY ANIMALS: Acute Exposure/ When rabbits inhaled 300 ppm of sulfur dioxide, ciliary action in the upper airways was inhibited, and at 400 ppm, mucosal irritation, mucous gland hypertrophy, and proliferation of pulmonary goblet cells occurred.
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. 1455
/LABORATORY ANIMALS: Acute Exposure/ Exposure-effect curves have been developed for guinea pigs ... and dogs ... In /the guinea pig/ study, a linear relationship was obtained between exposure for 1 hr to sulfur dioxide concn ranging from 0.46 to 2380 mg/cu m (0.16-835 ppm) and corresponding increases in pulmonary flow resistance. The /dog/ study showed that nasal flow resistance increased roughly in proportion to exposure to sulfur dioxide concentrations ranging from 20 to 660 mg/cu m (7-230 ppm) for a 15-20 min period.
WHO; Environmental Health Criteria 8: Sulfur Oxides and Suspended Particulate Matter (1979); Available from, as of November 21, 2017: https://www.inchem.org/pages/ehc.html
/LABORATORY ANIMALS: Acute Exposure/ After a 120-hr exposure to a sulfur dioxide concentration of 3 mg/cu m (1.1 ppm), guinea pigs showed proliferative interstitial pneumonia, bronchitis, and tracheitis and an increased histamine content in the lungs...
WHO; Environmental Health Criteria 8: Sulfur Oxides and Suspended Particulate Matter (1979); Available from, as of November 21, 2017: https://www.inchem.org/pages/ehc.html
/LABORATORY ANIMALS: Acute Exposure/ Spontaneously hypertensive (SH) and commonly used Sprague Dawley (SD) rats (male, 13- to 15-weeks old) /were exposed/ to 0, 250, or 350 ppm sulfur dioxide (SO(2)), 5 hr/day for 4 consecutive days to induce airway injury. SO(2) caused dose-dependent changes in breathing parameters in both strains with SH rats being slightly more affected than SD rats. Increases in bronchoalveolar lavage fluid (BALF) total cells and neutrophilic inflammation were dose dependent and significantly greater in SH than in SD rats. The recovery was incomplete at 4 days following SO(2) exposure in SH rats. Pulmonary protein leakage was modest in either strain, but lactate dehydrogenase and N-acetyl glucosaminidase activity were increased in BALF of SH rats. Airway pathology and morphometric evaluation of mucin demonstrated significantly greater impact of SO(2) in SH than in SD rats. Baseline differences in lung gene expression pattern suggested marked immune dysregulation, oxidative stress, impairment of cell signaling, and fatty acid metabolism in SH rats. SO(2) effects on these genes were more pronounced in SH than in SD rats...
Kodavanti UP et al; Toxicol Sci 94 (1): 193-205 (2006)
For more Non-Human Toxicity Excerpts (Complete) data for Sulfur dioxide (61 total), please visit the HSDB record page.

12.1.17 Non-Human Toxicity Values

LC50 Rat inhalation 2420 ppm/1 hr
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 3330
LC50 Mouse inhalation 3000 ppm/30 min
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 3330
LC50 Mice inhalation 150 ppm/847 hr
American Conference of Governmental Industrial Hygienists. Documentation of the TLVs and BEIs with Other World Wide Occupational Exposure Values. 7th Ed. CD-ROM Cincinnati, OH 45240-1634 2013.
LC50 Guinea pigs inhalation 130 ppm/154 hr
American Conference of Governmental Industrial Hygienists. Documentation of the TLVs and BEIs with Other World Wide Occupational Exposure Values. 7th Ed. CD-ROM Cincinnati, OH 45240-1634 2013.
For more Non-Human Toxicity Values (Complete) data for Sulfur dioxide (6 total), please visit the HSDB record page.

12.1.18 Populations at Special Risk

Persons with a history of asthma or with subnormal pulmonary function should be watched closely ... .
OSHA; Public Hearing on Occupational Standard for Sulfur Dioxide: Statement of Edward Baier (NIOSH) (May 1977) PB 83-182485
Clear cut evidence has ... been obtained that asthmatic individuals are especially sensitive to sulfur dioxide. ... The degree of sensitivity to Sulfur dioxide appears to depend on the magnitude of preexisting airway hypersensitivity.
Doull, J., C.D.Klassen, and M.D. Amdur (eds.). Casarett and Doull's Toxicology. 3rd ed., New York: Macmillan Co., Inc., 1986., p. 807
/EPIDEMIOLOGY STUDIES/ The potential effects of smoking and sulfur dioxide (SO2) were examined on lung function. Data were collected from family health examinations of 867 subjects, aged 20-86 yr, in a Korean community. The subjects responded to a questionnaire interview and completed lung function tests. Data on SO2 exposure were obtained from the Environmental Management Corporation. Studies showed that exposure to SO2 induced a short, marked decrease in forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1) in smokers compared with nonsmokers. The effect lasted up to 30 hr after exposure...
Min J-Y et al; J Toxicol Environ Health, Part A 71 (5): 301-3 (2008)

12.2 Ecological Information

12.2.1 Ecotoxicity Excerpts

/BIRDS and MAMMALS/ Research investigating the effects of air contaminants on biota has been limited to date. Captive adult female American kestrels (Falco sparverius) were exposed to a mixture of benzene (0.6 ppm), toluene (1 ppm), nitrogen dioxide (NO2; 2 ppm) and sulfur dioxide (SO2; 5.6 ppm), in a whole-body inhalation chamber. Thyroid axis responses to meet metabolic demands were examined through thyroid histology, plasma thyroxine (T4), and triiodothyronine (T3), and hepatic outer ring deiodination (T4-ORD). Plasma free (F) T3 and T4 were measured at baseline, and at 9 days and 18 days of exposure, whereas total (T) T3 and TT4, thyroid histology and hepatic T4-ORD were determined at the final 18 day exposure. Inhalation of these contaminants significantly suppressed plasma FT4 and TT4, and depleted follicular colloid and increased epithelial cell height at 18 days, and significantly altered the temporal pattern of plasma FT4. Significant histological changes in the follicular colloid:epithelial cell height ratio indicated sustained T4 production and release by the thyroid glands. There was no effect on plasma FT3, TT3, or hepatic T4-ORD. We hypothesize that contaminant-related activation of the hypothalamus-pituitary-thyroid axis in the kestrels increased elimination of plasma T4 through Phase II enzymes.
Fernie KJ et al; Environ Sci Technol. 2016 Oct 3. (Epub ahead of print)
/BIRDS and MAMMALS/ In the oil sands of Alberta, Canada, toxicology research has largely neglected the effects of air contaminants on biota. Captive Japanese quail (Coturnix c. japonica) and American kestrels (Falco sparverius) were exposed to mixtures of volatile organic compounds and oxidizing agents (benzene, toluene, NO2 and SO2) in a whole-body inhalation chamber, to test for toxicological responses. Hepatic biotransformation measured through 7-ethoxyresorufin-O-dealkylase (EROD) tended to be increased in exposed kestrels (p=0.06) but not in quail (p=0.15). Plasma corticosterone was increased in the low dose group for quail on the final day of exposure (p=0.0001), and midway through the exposure period in exposed kestrels (p=0.04). For both species, there was no alteration of T and B-cell responses, immune organ mass, or histology of immune organs (p>0.05).
Cruz-Martinez L et al; Ecotoxicol Environ Saf 112: 223-30 (2015)
/AQUATIC SPECIES/ ... 16 to 19 ppm of sulfur dioxide killed sunfish in 1 hr. ... Concentrations of 10 ppm of sulfur dioxide in tap water caused trout to float within 10 min and also reports that 5 ppm of sulfur dioxide killed trout in 1 hr.
Nat'l Research Council Canada; Sulfur and its Inorganic Derivatives in the Canadian Environment p.270 (1977) NRCC No. 15015
/PLANTS/ Nitrogen dioxide (NO2) and sulfur dioxide (SO2) generated by excessive coal combustion and motor vehicle emissions are major air pollutants in the large cities of China. The objective of our study was to determine the effects of the exposure of oak pollens (Quercusmongolica) to several concentrations of NO2 or SO2. Pollen grains were exposed to 0.5 ppm to 5.0 ppm NO2 or SO2 for 4 hours and assessed for morphological damage by field emission scanning electron microscopy and for viability using the trypan blue stain. Morphological changes in pollen grains were also examined after contact with acid solutions at pH 4.0 to pH 7.0. Exposure to NO2 or SO2 significantly damaged pollen grains at all concentrations investigated, compared to exposure to air; with exposure to concentrations of 0.5 ppm to 2 ppm resulting in fissures or complete breaks in the exine and a concentration of 5 ppm resulting in complete breakdown and release of pollen cytoplasmic granules. Significantly greater amounts of pollen grain were damaged after exposure to SO2 (15.5-20.4%) than after exposure to NO2 (7.1-14.7%). Similarly, exposure to NO2 or SO2 significantly decreased the viability of pollen grains, compared with exposure to air; with SO2 being slightly more detrimental than NO2. Exposure to acid solutions also induced pollen damage, which appeared to be pH-dependent (from 24.6% at pH 6.0 to 55.8% at pH 4.0; compared to 3.8% at pH 7.0). Short-term exposure of oak pollen to high concentrations of SO2 or NO2 significantly increases their fragility and disruption, leading to subsequent release of pollen cytoplasmic granules into the atmosphere. These results suggest that heightened air pollution during the oak pollen season may possibly increase the incidence of allergic airway disease in sensitized individuals by facilitating the bioavailability of airborne pollen allergens.
Ouyang Y et al; Int Forum Allergy Rhinol 6 (1): 95-100 (2016)
For more Ecotoxicity Excerpts (Complete) data for Sulfur dioxide (18 total), please visit the HSDB record page.

12.2.2 ICSC Environmental Data

The substance is harmful to aquatic organisms.

12.2.3 Environmental Fate / Exposure Summary

Sulfur dioxide's production from fuel combustion will result in its direct release to the environment. On a global basis, fossil fuel combustion accounts for 75 to 85% of man-made sulfur dioxide emissions, and industrial processes such as refining and smelting account for the remainder. The global sulfur cycle involves an atmospheric flux of about (140-350)X10+6 tons/annum, with (40-60)X10+6 tons as anthropogenic sulfur, in the form of sulfur dioxide, sulfuric acid, and sulfate. Sulfur dioxide can react with other compounds in the atmosphere and form fine particles that result in haze that reduces visibility. Particulate matter pollution is the major cause of haze in parts of the US. Sulfur dioxide's production and use in preserving fruits, vegetables; disinfectant in breweries and food factories; bleaching textile fibers, straw, wicker ware, gelatin, glue, beet sugars, solvent and reagent in organic synthesis may result in its release to the environment through various waste streams. It's use as a fungicide and acaricide in the wine industry will result in its direct release to the environment. Sulfur dioxide is released to the air from volcanic activity and eruptions. If released to air, a vapor pressure of 3.0X10+3 mm Hg at 25 °C indicates sulfur dioxide will exist solely as a gas in the atmosphere. Gas-phase sulfur dioxide is oxidized rapidly by homogeneous and heterogeneous reactions. The oxidation of sulfur dioxide to sulfuric acid and sulfates in the atmosphere is an important contributor to air pollution, specifically producing acid rain. Sulfur dioxide dissolves in water, forming a weak acid solution of sulfurous acid. This acid rain effects sensitive forest, soil and aquatic ecosystems. The atmospheric lifetime of sulfur dioxide is about 10 days. Sulfur dioxide may be photochemically or catalytically oxidized to SO3 and sulfate in air. If released to soil, sulfur dioxide is expected to absorb to soil. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 8.10X10-4 atm-cu m/mole. Sulfur dioxide is expected to volatilize from dry soil surfaces based upon its vapor pressure. Sulfur dioxide has been shown to be reduced to H2S using heat- and alkali-treated sewage sludge by certain sulfate reducing bacteria. If released into water, sulfur dioxide is not expected to adsorb to suspended solids and sediment based upon its rapid reaction with water to form sulfuric acid. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's reactivity with water. Occupational exposure to sulfur dioxide may occur through inhalation and dermal contact with this compound at workplaces where sulfur dioxide is produced or used. Monitoring data indicate that the general population may be exposed to sulfur dioxide via inhalation of ambient air, smoking cigarettes, ingestion of food, and dermal contact with consumer products containing sulfur dioxide. (SRC)

12.2.4 Natural Pollution Sources

Volcanoes and volcanic vent activity contribute to the levels of atmospheric sulfur dioxide(1,2). Natural sources of sulfur dioxide also include decaying organic matter, and the action of the sun on seawater(2). Oceans may be a source of sulfur dioxide under times of barometric imbalance(1). Sulfur dioxide is believed to be the main sulfur compound produced by oxidation of dimethyl sulfide that is emitted from the ocean(2). Sea salt can also contribute to atmospheric levels of sulfate(1). Sulfur dioxide is a component of marihuana and cotton(3).
(1) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp
(2) Weil ED et al; Sulfur Compounds. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2018). New York, NY: John Wiley & Sons. Online Posting Date: 16 Jun 2006
(3) Dr. Duke's Phytochemical and Ethnobotanical Databases. Theobromine. Available from, as of Oct 13, 2017: https://phytochem.nal.usda.gov/phytochem/search
Hydrogen sulfide, from the natural decay of vegetation on land, marsh lands and in the oceans, is probably oxidized to sulfur dioxide within hours.
Monitoring and Assessment Research Centre; Report #7 p.4 (1978)
Sulfur accounts for 15% of the inner core of the earth and 0.052% of its crust. The total sulfur content of the earth is estimated to be approximately 18.2X10+145 tons. The global sulfur cycle involves an atmospheric flux of about (140-350)X10+6 tons/annum, with (100-290)X10+6 tons involving biological decay, sea spray and volcanic activity. Sulfur also particiaptes in microbial cycles. /Sulfur/
Seiler, H.G., H. Sigel and A. Sigel (eds.). Handbook on the Toxicity of Inorganic Compounds. New York, NY: Marcel Dekker, Inc. 1988., p. 640, 654

12.2.5 Artificial Pollution Sources

Sulfur dioxide's production from fuel combustion will result in its direct release to the environment(1). Sulfur dioxide in the atmosphere is formed as a by-product of fuel combustion from power generation and industrial processes, and by the oxidation of reduced gases in the air(2). Sulfur dioxide can react with other compounds in the atmosphere and form fine particles that result in haze that reduces visibility. Particulate matter pollution is the major cause of haze in parts of the world(3). Sulfur dioxide's production and use for preserving fruits, vegetables; disinfectant in breweries and food factories; bleaching textile fibers, straw, wicker ware, gelatin, glue, beet sugars, solvent and reagent in organic synthesis(4) may result in its release to the environment through various waste streams. It's use as a fungicide and acaricide in the wine industry will result in its direct release to the environment(5). Sulfur dioxide is a constituent of tobacco smoke(6).
(1) Weil ED et al; Sulfur Compounds. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2018). New York, NY: John Wiley & Sons. Online Posting Date: 16 Jun 2006
(2) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp
(3) USEPA; Sulfur Dioxide (SO2) Pollution. Washington, DC: US EPA. Available from, as of Feb 14, 2018: https://www.epa.gov/so2-pollution
(4) O'Neil MJ, ed; The Merck Index. 15th ed., Cambridge, UK: Royal Society of Chemistry, p. 1659 (2013)
(5) USEPA/OPP: Pesticide Chemical Search. Sulfur dioxide. (7446-09-5). Washington, DC: Environmental Protection Agency, Office of Pesticide Programs. Available from, as of Oct 17, 2017: https://iaspub.epa.gov/apex/pesticides/f?p=chemicalsearch:1
(6) Rodgman A, Perfetti TA; The Chemical Components of Tobacco and Tobacco Smoke. Boca Raton, FL: CRC Press p. 870 (2009)
The oxidation of sulfur dioxide to sulfuric acid and sulfates in the atmosphere is an important contributor to air pollution, specifically producing acid rain. Sulfur dioxide dissolves in water, forming a weak acid solution of sulfurous acid. This acid rain effects sensitive forest, soil and aquatic ecosystems. Sulfur in precipitation is, up to a point, beneficial to plant growth as sulfur is an essential element. At low levels, sulfur dioxide in the atmosphere is not harmful to crops but damage can occur at high levels. The 1990 Clean Air Act Amendments were designed to cut annual sulfur dioxide emissions 40% from 1980 levels, and thereby decrease the effects of acid rain, which can cause damage at great distances from the source of emission. Estimated emissions in the USA declined from 25.7X10+6 tons in 1980 to approximately 20X10+6 tons in 2006; approximately 65% of emissions is attributable to electric utilities. Regulatory action to limit sulfur emissions is applicable to power generation, the selection of fuel and the coal mining, gas and petroleum industries. A large part of the amount of sulfur dioxide in the atmosphere is attributed to burning sulfur-containing fuel, notably coal, and smelting sulfide ores(1).
(1) Weil ED et al; Sulfur Compounds. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2018). New York, NY: John Wiley & Sons. Online Posting Date: 16 Jun 2006
On a global basis, fossil fuel combustion accounts for 75 to 85% of man-made sulfur dioxide emissions, and industrial processes such as refining and smelting account for the remainder.
Friend JP; Chemistry of the Lower Atmosphere pp.177-201 (1973) as cited in Monitoring and Assessment Research Centre; Report #7 p.5 (1978)
It is estimated that 93.5% of sulfur dioxide pollution is produced in the Northern Hemisphere, and the remaining 6.5% in the Southern Hemisphere.
Kellogg WW et al; Science 175: 587 (1972) as cited in Monitoring and Assessment Research Centre; Report #7 p.7 (1978)
For more Artificial Pollution Sources (Complete) data for Sulfur dioxide (7 total), please visit the HSDB record page.

12.2.6 Environmental Fate

Sulfur dioxide (SO2) is an atmospheric pollutant that is moderately persistent in the atmosphere and highly water soluble. When applied as a pesticide, SO2 may be transported, deposited, or transformed in various chemical reactions. SO2 participates in the sulfur biogeochemical cycle, which involves complex reactions of sulfur-containing compounds between abiotic and biotic components of ecosystems. The main degradation route of SO2 is atmospheric oxidation, and sulfur oxides may undergo long-distance transport prior to removal from the atmosphere by wet or dry deposition. According to the Pesticide Use Reporting (PUR) database maintained by the California Department of Pesticide Regulation (DPR), SO2 use in California from 2010 to 2015 was primarily for fumigations (96%), including treatments of postharvest grape products and winery equipment sterilizations. Other site uses contributed less than 5% of reported statewide SO2 use from 2010 to 2015. A slight increasing trend in use of SO2 as a pesticide was observed from 2010 to 2015, with the highest reported uses of SO2 within California counties during the months of July-November. Although the primary sources of SO2 in the environment are anthropogenic emissions from the combustion of fossil fuels, emissions of SO2 from pesticide uses have the potential to contribute to the environmental and public welfare impacts of SO2 pollution. Oxidation of atmospheric SO2 may contribute to the negative environmental and public welfare impacts of acid rain, which include toxicity to aquatic organisms, fish, and terrestrial vegetation, and corrosion of man-made materials.
Craig K; Rev Environ Contam Toxicol Epub ahead of print March (2018)
TERRESTRIAL FATE: Sulfur dioxide may be absorbed by soil(1). Volatilization of sulfur dioxide from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 8.10X10-4 atm-cu m/mole(2). However, reaction with water to sulfuric acid is expected to attenuate volatilization(SRC). Sulfur dioxide is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 3.0X10+3 mm Hg at 25 °C(3). Biodegradation data in soil were not available(SRC, 2018). However, a sulfate-reducing bacteria isolated from sewage sludge was shown to biodegrade sulfur dioxide to hydrogen sulfide(1).
(1) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp
(2) Betterton EA; Henry's Law Constants of Soluble and Moderately Soluble Organic Gases: Effects on Aqueous Phase Chemistry. Gas Pollut Character Cycl. John Wiley and Sons, Inc. pp. 1-50 (1992)
(3) Daubert TE, Danner RP; Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, DC: Taylor and Francis (1989)
TERRESTRIAL FATE: Although snow covered surfaces are inefficient receptors of gaseous and particulate sulfur cmpd, the spring melt of the accumulated winter snowpack can result in rapid, short term inputs of high sulfate, low pH water to freshwater systems with resulting disastrous effects on fish.
Monitoring and Assessment Research Centre; Report #7 p.21 (1978)
AQUATIC FATE: Sulfur dioxide may be absorbed by water and snow covers. Melting snowpacks in spring can result in short-term high input of sulfate into freshwater(1). Volatilization from water surfaces is(2) based upon a Henry's Law constant of 8.10X10-4 atm-cu m/mole(3). However, reaction in water is expected to attenuate this process(SRC). Biodegradation data in water were not available(SRC, 2018). However, a sulfate-reducing bacteria isolated from sewage slduge was shown to biodegrade sulfur dioxide to hydrogen sulfide(1).
(1) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp
(2) US EPA; Estimation Program Interface (EPI) Suite. Ver. 4.11. Nov, 2012. Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 15-1 to 15-29 (1990)
(3) Betterton EA; Henry's Law Constants of Soluble and Moderately Soluble Organic Gases: Effects on Aqueous Phase Chemistry. Gas Pollut Character Cycl. John Wiley and Sons, Inc. pp. 1-50 (1992)
For more Environmental Fate (Complete) data for Sulfur dioxide (10 total), please visit the HSDB record page.

12.2.7 Environmental Biodegradation

PURE CULTURE: Sulfur dioxide has been shown to be reduced to H2S (hydrogen sulfide) using heat- and alkali-treated sewage sludge by the sulfate reducing bacteria, Desulfovbrio desulfuricans or Desuotomaculum orientis(1).
(1) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp

12.2.8 Environmental Abiotic Degradation

The oxidation of sulfur dioxide to sulfuric acid and sulfates in the atmosphere is important with regard to air pollution studies. Radicals, e.g. hydrogen monoxide, water, and carboxcylic acid, appear to be the principal species responsible for the homogeneous oxidation of sulfur dioxide in the atmosphere, which occurs at rates as high as 4.0%/hr(1). Sulfur dioxide is oxidized rapidly by homogeneous and heterogeneous reactions and is removed from the atmosphere by precipitation and by dry deposition on surfaces, mainly as sulfuric acid(2). Sulfur dioxide in air can be oxidized to sulfate by cloud or rain droplets and thus form "acid rain"(1). Meteorologic conditions resulted in high acidic pollution during the summer months in Ohio, Pennsylvania, Virginia, West Virginia, Tennessee and Kentucky. The EPA Acid Rain Program projected a 40% reduction in sulfur dioxide yearly emissions in the US between 1980 and 2010, which would also contribute to less sulfate haze(2). Sulfur dioxide may be photochemically or catalytically oxidized to SO3 and sulfate in air. The atmospheric lifetime of sulfur dioxide is about 10 days(2). .
(1) Weil ED et al; Sulfur Compounds. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 16 Jun 2006
(2) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp
Suggested values of reaction rates for gas phase oxidation of sulfur dioxide to sulfate for the western European summer range from 0.5 to 5%/hr in sunlight, depending on the degree of pollution of the atmosphere, with the lower figure relating to clean air. This oxidation involves other short lived pollutants which have been photochemically generated, therefore, the direct photo-oxidation of sulfur dioxide is not important. Because these reactions are dependent on solar radiation, their importance decreases significantly in winter time and at night.
Eggleton A EJ, Cox RA; Atomospheric Environment (1978) as cited in Monitoring and Assessment Research Centre; Report #7 p.11 (1978)
Catalyzed, liquid phase, oxidation /of sulfur dioxide/ in the presence of metals (e.g. iron, manganese) is important in urban plumes and perhaps urban fogs where their concentrations are sufficiently high, but probably not in cleaner, rural air.
Monitoring and Assessment Research Centre; Report #7 p.11 (1978)
Liquid phase oxidation involving the strong oxidizing agents ozone and hydrogen peroxide may also be very important (e.g. hydrogen sulfide and other organic sulfides oxidized to sulfur dioxide); however, reaction rates and atmospheric concentrations, respectively, for these two substances are not sufficiently well known.
Monitoring and Assessment Research Centre; Report #7 p.11 (1978)
For more Environmental Abiotic Degradation (Complete) data for Sulfur dioxide (6 total), please visit the HSDB record page.

12.2.9 Soil Adsorption / Mobility

Sulfur dioxide can be absorbed by soil. In the form of acid rain it is the leading cause of an increase in heavy metal mobility in soil(1).
(1) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp
Sulfur dioxide uptake is dependent upon soil pH and moisture content.
Payrissat M, Beilke S; Atmos Environ 9: 211 (1975) as cited in Monitoring and Assessment Research Centre; Report #7 p.21 (1978)

12.2.10 Volatilization from Water / Soil

The Henry's Law constant for sulfur dioxide is 8.10X10-4 atm-cu m/mole(1). This Henry's Law constant indicates that sulfur dioxide is expected to volatilize from water surfaces(2). Sulfur dioxide's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). However volatilization may be attenuated by reaction with water to form sulfuric acid(SRC). Sulfur dioxide is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 3.0X10+3 mm Hg(3).
(1) Betterton EA; Henry's Law Constants of Soluble and Moderately Soluble Organic Gases: Effects on Aqueous Phase Chemistry. Gas Pollut Character Cycl. John Wiley and Sons, Inc. pp. 1-50 (1992)
(2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 15-1 to 15-29 (1990)
(3) Daubert TE, Danner RP; Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis (1989)

12.2.11 Environmental Water Concentrations

RAIN/SNOW/FOG: It has been estimated that 70% of the sulfate that is present in rainwater comes from the washout of sulfur dioxide from the atmosphere(1).
(1) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp

12.2.12 Effluent Concentrations

Fossil fuel accounts for 75-85% of man-made sulfur dioxide emissions; 93.5% of these emissions originate in the Northern Hemisphere. Fuel combustion for electrical utilities accounted for the greatest portion of total sulfur dioxide emissions in the US, with Ohio and Indiana ranked the highest for emissions. Sulfur dioxide emissions have exhibited a steady decrease in the US since the 1970s(1). Sulfur dioxide was reported at 383 ppm in plume emissions from a coal-burning industrial power plant near Dayton, OH(2). Sulfur dioxide concentration of 23.61 kg/yr was reported for diesel exhaust from vehicles on a very large dairy operation in the Po Valley, northern Italy(3).
(1) ATSDR; Toxicological Profile for Sulfur Dioxide. December, 1988. Atlanta, GA: Agency for Toxic Substances and Disease Registry, US Public Health Service. Available from, as of Oct 13, 2013: https://www.atsdr.cdc.gov/toxprofiles/index.asp
(2) Gross KC et al; Environ Sci Technol 44: 9390-97 (2010)
(3) Battini F et al; Sci Total Environ 481: 196-208 (2014)

Trend in world-wide sulfur dioxide emissions(1).

Table: Global SO2 Emission Trends

Year
1990
World (Tg SO2)
120
China (Tg SO2)
16
India (Tg SO2)
3.5
Year
1995
World (Tg SO2)
110
China (Tg SO2)
20
India (Tg SO2)
4.25
Year
2000
World (Tg SO2)
105
China (Tg SO2)
24
India (Tg SO2)
5.5
Year
2005
World (Tg SO2)
115
China (Tg SO2)
32
India (Tg SO2)
7
Year
2010
World (Tg SO2)
102
China (Tg SO2)
29
India (Tg SO2)
10

(1) Klimont Z et al; Environ Res Letters 8: 014003 (6pp) (2013). Available from, as of Feb 14, 2018: https://dx.doi.org/10.1088/1748-9326/8/1/014003
Sulfur dioxide emissions from Connecticut sources in 2008 amounted to 20,000 tons. 3000 tons were attributed to mobile sources and 17,000 tons from stationary/area sources. 96% of stationary/area source sulfur dioxide emissions were generated by the combustion of residential and commercial heating oil and electricity generation. New York State requires the use of ultra-low sulfur heating oil (less than or equal to 15 ppm). Rhode Island adopted a sulfur rule in 2013. Maine, Massachusetts, New Jersey, Pennsylvania and Vermont have rules requiring low-sulfur fuels by 2018(1).
Source
Residential
Percentage
60
Source
Electrical Generation
Percentage
25
Source
Mobile Off-Road
Percentage
9
Source
Mobile On-Road
Percentage
4
Source
Other
Percentage
2
(1) CT DEEP; Fact Sheet. Reduction of Sulfur Dioxide Emissions and Fuel Sulfur Content. (2013). Hartford, CT: Conn Dept Energy Environ Prot. Available from, as of Feb 15, 2018: https://ct.gov/deep/lib/deep/air/siprac/2013/fuel_sulfur_factsheet.pdf
This study aims to estimate the emissions of carbon dioxide (CO2), sulfur dioxide (SO2), and nitric oxide (NO) for coal combustion in thermal power plants in India using plant-specific emission factors during the period of 2001/02 to 2009/10. The mass emission factors have been theoretically calculated using the basic principles of combustion under representative prevailing operating conditions in the plants and fuel composition. The results show that from 2001/02 to 2009/10 period, total CO2 emissions have increased from 324 to 499 Mt/year; SO2 emissions have increased from 2,519 to 3,840 kt/year; and NO emissions have increased from 948 to 1,539 kt/year from the Indian coal-fired power plants. National average emissions per unit of electricity from the power plants do not show a noticeable improvement during this period. Emission efficiencies for new plants that use improved technology are found to be better than those of old plants. As per these estimates, the national average of CO2 emissions per unit of electricity varies between 0.91 and 0.95 kg/kWh while SO2 and NO emissions vary in the range of 6.9 to 7.3 and 2.8 to 2.9 g/kWh, respectively. Yamunagar plant in Haryana state showed the highest emission efficiencies with CO2 emissions as 0.58 kg/kWh, SO2 emissions as 3.87 g/kWh, and NO emissions as 1.78 g/kWh, while the Faridabad plant has the lowest emission efficiencies with CO2 emissions as 1.5 kg/kWh, SO2 emissions as 10.56 g/kWh, and NO emissions as 4.85 g/kWh. Emission values at other plants vary between the values of these two plants.
Mittal ML et al; Environ Monit Asses 186(10): 6857-66 (2014)
For more Effluent Concentrations (Complete) data for Sulfur dioxide (8 total), please visit the HSDB record page.

12.2.13 Atmospheric Concentrations

URBAN/SUBURBAN: The sulfur dioxide mean 8-hr max concentration was 4.6 ppb in a high traffic area of Los Angeles County, CA, measured November 1999 through January 2000(1). Sulfur dioxide levels of 76.2 and 55.2 ug/cu m were reported in urban and suburban areas, respectively, measured in Eskisehir, Turkey. A concentration of 57.5 ug/cu m was reported for an urban traffic area. Testing was conducted in winter, February 27-March 13, 2009(2). Average sulfur dioxide concentrations of 2.8 and 3.2 ug/cu m were measured in urban and suburban environments, respectively, in Mallorca (Balearic Islands) measured from 2000 to 2012. The regional background concentration was 2.3 ug/cu m. Levels are influenced by power generation and an increased maritime traffic(3). Concentration ranges were: 2.55-17.43 ppb (winter); 1.48-15.55 ppb (summer); 1.24-6.37 ppb (monsoon) during 2008 in New Delhi, India(4). Sulfur dioxide concentrations were observed to fluctuate from 0 to 150 ug/cu m in a study of urban pollution and haze clouds over Beijing, China during the dusty season in March 2013(5). The arithmetic mean concentration for the years 2004 to 2010 for sulfur dioxide, based on 85 major city regions of China, was 19.87 ug/cu m (5.78 ug/cu m, min; 118 ug/cu m max)(6).
(1) Delfino RJ et al; Environ Health Perspect 111(4): 647-656 (2003)
(2) Altug H et al; Sci Total Environ 479-480: 201-209 (2014)
(3) Cerro JC et al; Atmos Environ 103: 138-146 (2015)
(4) Datta A et al; J Atmos Chem: 127-143 (2010)
(5) Tao M et al; Atmos Environ 82: 183-192 (2014)
(6) Wang L et al; Sci Total Environ 487: 57-64 (2014)
RURAL/REMOTE: Sulfur dioxide exhibited a yearly average of 1.1 ppb following a 15-year (1997-2011) term assessment of air quality from a background station at Jeranut, Pahang on the Malaysian Peninsula(1).
(1) Latif MT et al; Sci Total Environ 482-483: 336-348 (2014)
RURAL/REMOTE: A mean sulfur dioxide level of 2.6 ppbw was reported for a relatively pristine region in western Maryland that is >50 km downwind of power plants in Ohio, Pennsylvania and West Virginia; sampling was conducted from 2006 to 2014(1).
Year
2006
Concn (ppbw)
4.9
Year
2011
Concn (ppbw)
1.8
Year
2007
Concn (ppbw)
4.8
Year
2012
Concn (ppbw)
1.2
Year
2008
Concn (ppbw)
3.8
Year
2013
Concn (ppbw)
1.3
Year
2009
Concn (ppbw)
3.1
Year
2014
Concn (ppbw)
1.4
Year
2010
Concn (ppbw)
2.4
(1) Castro MS, Sherwell J; Environ Sci Technol 49(24): 14000-14007 (2015)
SOURCE DOMINATED: Sulfur dioxide Combustion Emissions(1).
Combusted Source
Natural Gas
Pounds/billion Btu of energy input
0.6
Combusted Source
Oil
Pounds/billion Btu of energy input
1,122
Combusted Source
Coal
Pounds/billion Btu of energy input
2,591
(1) U.S. Department of Energy; Modern shale gas development in the United State: A primer. Washington, DC: U.S. Department of Energy, Office of Fossil Energy, National Energy Technology Laboratory (2009)
For more Atmospheric Concentrations (Complete) data for Sulfur dioxide (9 total), please visit the HSDB record page.

12.2.14 Food Survey Values

Sulfur dioxide was detected, not quantified on food samples analyzed in 1989 and 1990 as part of regulatroy monitoring of US and imported foods samples(1,2).
(1) FDA; Food and Drug Administration Pesticide Program. Residues in Foods - 1989. J AOAC Int 73: 127A-46A (1990)
(2) FDA; Food and Drug Administration Pesticide Program. Residues in Foods - 1990. J AOAC Int 74: 121A-41A (1991)
Sulfur dioxide has been reported found in oragne juice, grapefruit juice, onion, boiled and cooked beef, starfruit and weinbrand brandy.
Burdock, G.A. (ed.). Fenaroli's Handbook of Flavor Ingredients. 6th ed.Boca Raton, FL 2010, p. 1859

12.2.15 Plant Concentrations

Sulfur dioxide concentrations ranged from not detected to 13 ug/cu m in bryophytes from the Biosphere Reserve Wienerwald, Vienna, Austria. The reserve is characterized by a large-scale broad-leaf forest (Quercus petraea, Tilia platyphyllos, Acer platanoides, Acer campestre) and is adjacent to high traffic roadways(1).
(1) Krommer V et al; Chemosphere 67: 1956-1966 (2007)
Sulfur dioxide occurrence in plants(1).
Genus species
Gossypium sp
Family
Malvaceae
Common names
Cotton
Part
Seed
Concn (ppm)
1700-2800
Genus species
Cannabis sativa
Family
Cannabaceae
Common names
Indian Hemp; Marijuana; Hemp; Marihuana
Part
Seed
Concn (ppm)
85-135
(1) Dr. Duke's Phytochemical and Ethnobotanical Databases. Theobromine. Available from, as of Oct 17, 2017: https://phytochem.nal.usda.gov/phytochem/search

12.2.16 Other Environmental Concentrations

Sulfur dioxide is a constituent of tobacco smoke and tobacco substitute smoke(1).
(1) Rodgman A, Perfetti TA; The Chemical Components of Tobacco and Tobacco Smoke. Boca Raton, FL: CRC Press p. 870 (2009)
It was found that sulfur dioxide was taken up from atmosphere by sulfate treated plants ... .
Fenaroli's Handbook of Flavor Ingredients. Volume 1. Edited, translated, and revised by T.E. Furia and N. Bellanca. 2nd ed. Cleveland: The Chemical Rubber Co., 1975., p. 165

12.2.17 Probable Routes of Human Exposure

According to the 2016 TSCA Inventory Update Reporting data, 8 reporting facilities estimate the number of persons reasonably likely to be exposed during the manufacturing, processing, or use of sulfur dioxide in the United States may be as low as 10 workers to less than 500 but unknown or unreasonably ascertainable as to how many workers per plant; the data may be greatly underestimated due to confidential business information (CBI) or unknown values(1).
(1) US EPA; Chemical Data Reporting (CDR). Non-confidential 2016 Chemical Data Reporting information on chemical production and use in the United States. Available from, as of Oct 16, 2017: https://www.epa.gov/chemical-data-reporting
NIOSH (NOES Survey 1981-1983) has statistically estimated that 55,033 workers (8,990 of these were female) were potentially exposed to sulfur dioxide in the US(1). The NOES Survey does not include farm workers. Monitoring data indicate that the general population may be exposed to sulfur dioxide via inhalation of ambient air, smoking cigarettes, ingestion of food, and dermal contact with consumer products containing sulfur dioxide(SRC).
(1) CDC; International Chemical Safety Cards (ICSC) 2012. Atlanta, GA: Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health (NIOSH). Ed Info Div. Available from, as of Oct 13, 2017: https://www.cdc.gov/niosh/ipcs/default.html
Inhalation ... /or/ direct contact of gas or liquid phase on ... mucous membranes.
Sittig, M. Handbook of Toxic and Hazardous Chemicals and Carcinogens, 1985. 2nd ed. Park Ridge, NJ: Noyes Data Corporation, 1985., p. 813
It has been estimated by the Department of Labor that approx 600,000 American workers may be occupationally exposed to sulphur dioxide. Some of the highest exposures occur when it is a by product, as in the metal smelting industry, and in the processing or combustion of high sulfur coal or oil. Other exposures occur in manufacture of sulfuric acid, fumigating, food preservation, wine making, and bleaching of many substances.
OSHA; Public Hearing on Occupational Standard for Sulfur Dioxide: Statement of Edward Baier (NIOSH) (May 1977) PB 83-182485

13 Associated Disorders and Diseases

Associated Occupational Diseases with Exposure to the Compound

Fumigants, acute toxic effect [Category: Acute Poisoning]

Bronchiolitis obliterans [Category: Airway Disease]

Pneumonitis, toxic [Category: Acute Poisoning]

Pulmonary disease, chronic obstructive [Category: Airway Disease]

14 Literature

14.1 Consolidated References

14.2 NLM Curated PubMed Citations

14.3 Springer Nature References

14.4 Thieme References

14.5 Wiley References

14.6 Chemical Co-Occurrences in Literature

14.7 Chemical-Gene Co-Occurrences in Literature

14.8 Chemical-Disease Co-Occurrences in Literature

15 Patents

15.1 Depositor-Supplied Patent Identifiers

15.2 WIPO PATENTSCOPE

15.3 Chemical Co-Occurrences in Patents

15.4 Chemical-Disease Co-Occurrences in Patents

15.5 Chemical-Gene Co-Occurrences in Patents

16 Interactions and Pathways

16.1 Protein Bound 3D Structures

16.1.1 Ligands from Protein Bound 3D Structures

PDBe Ligand Code
PDBe Structure Code
PDBe Conformer

16.2 Chemical-Target Interactions

16.3 Pathways

17 Biological Test Results

17.1 BioAssay Results

18 Taxonomy

The LOTUS Initiative for Open Natural Products Research: frozen dataset union wikidata (with metadata) | DOI:10.5281/zenodo.5794106

19 Classification

19.1 MeSH Tree

19.2 ChEBI Ontology

19.3 ChemIDplus

19.4 CAMEO Chemicals

19.5 UN GHS Classification

19.6 EPA CPDat Classification

19.7 NORMAN Suspect List Exchange Classification

19.8 EPA DSSTox Classification

19.9 International Agency for Research on Cancer (IARC) Classification

19.10 Consumer Product Information Database Classification

19.11 EPA TSCA and CDR Classification

19.12 LOTUS Tree

19.13 EPA Substance Registry Services Tree

19.14 MolGenie Organic Chemistry Ontology

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  24. European Chemicals Agency (ECHA)
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  34. ChEMBL
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    http://www.ebi.ac.uk/Information/termsofuse.html
  35. Comparative Toxicogenomics Database (CTD)
    LICENSE
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    http://ctdbase.org/about/legal.jsp
  36. Crystallography Open Database (COD)
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    https://creativecommons.org/publicdomain/zero/1.0/
  37. EPA Chemical and Products Database (CPDat)
  38. Hazardous Chemical Information System (HCIS), Safe Work Australia
  39. NITE-CMC
    Sulfur dioxide - FY2006 (New/original classication)
    https://www.chem-info.nite.go.jp/chem/english/ghs/06-imcg-0863e.html
  40. Regulation (EC) No 1272/2008 of the European Parliament and of the Council
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    https://eur-lex.europa.eu/content/legal-notice/legal-notice.html
    sulphur dioxide; sulfur dioxide
    https://eur-lex.europa.eu/eli/reg/2008/1272/oj
  41. FDA Substances Added to Food
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    https://www.fda.gov/about-fda/about-website/website-policies#linking
  42. Flavor and Extract Manufacturers Association (FEMA)
  43. International Agency for Research on Cancer (IARC)
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    https://publications.iarc.fr/Terms-Of-Use
    IARC Classification
    https://www.iarc.fr/
  44. Japan Chemical Substance Dictionary (Nikkaji)
  45. KEGG
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    https://www.kegg.jp/kegg/legal.html
  46. NIOSH Manual of Analytical Methods
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    https://www.cdc.gov/Other/disclaimer.html
  47. NIST Mass Spectrometry Data Center
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    https://www.nist.gov/srd/public-law
  48. SpectraBase
  49. NLM RxNorm Terminology
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    https://www.nlm.nih.gov/research/umls/rxnorm/docs/termsofservice.html
  50. NMRShiftDB
  51. Protein Data Bank in Europe (PDBe)
  52. RCSB Protein Data Bank (RCSB PDB)
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  53. Springer Nature
  54. SpringerMaterials
  55. Thieme Chemistry
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    https://creativecommons.org/licenses/by-nc-nd/4.0/
  56. Wikidata
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  58. Wiley
  59. Medical Subject Headings (MeSH)
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    https://www.nlm.nih.gov/copyright.html
  60. PubChem
  61. GHS Classification (UNECE)
  62. NORMAN Suspect List Exchange
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    https://creativecommons.org/licenses/by/4.0/
    NORMAN Suspect List Exchange Classification
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  63. EPA Substance Registry Services
  64. MolGenie
    MolGenie Organic Chemistry Ontology
    https://github.com/MolGenie/ontology/
  65. PATENTSCOPE (WIPO)
  66. NCBI
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