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Magnesium Oxide

PubChem CID
14792
Structure
Magnesium Oxide_small.png
Molecular Formula
Synonyms
  • oxomagnesium
  • Magnesia
  • Granmag
  • Calcined magnesia
  • Seawater magnesia
Molecular Weight
40.305 g/mol
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Dates
  • Create:
    2005-03-27
  • Modify:
    2025-01-18
Description
Magnesium oxide appears as a white solid, often found as a powder. When fine particles of magnesium oxide are dispersed in air, whether directly or when generated by the burning or cutting of magnesium metal, the resulting magnesium oxide fume is an inhalation hazard.
Magnesium oxide is an inorganic compound that occurs in nature as the mineral periclase. In aqueous media combines quickly with water to form magnesium hydroxide. It is used as an antacid and mild laxative and has many nonmedicinal uses.
Magnesium Oxide is the oxide salt of magnesium with antacid, laxative and vascular smooth muscle relaxant activities. Magnesium combines with water to form magnesium hydroxide which reacts chemically to neutralize or buffer existing quantities of stomach acid; stomach-content and intra-esophageal pH rise, resulting in a decrease in pepsin activity. This agent's laxative effect is the result, in part, of osmotically mediated water retention, which subsequently stimulates peristalsis. In addition, magnesium ions may behave as calcium antagonists in vascular smooth muscle.
See also: Magnesium Cation (has active moiety); Periclase (narrower); Prepopik (component of) ... View More ...

1 Structures

1.1 2D Structure

Chemical Structure Depiction
Magnesium Oxide.png

1.2 3D Status

Conformer generation is disallowed since MMFF94s unsupported element

2 Names and Identifiers

2.1 Computed Descriptors

2.1.1 IUPAC Name

oxomagnesium
Computed by Lexichem TK 2.7.0 (PubChem release 2021.10.14)

2.1.2 InChI

InChI=1S/Mg.O
Computed by InChI 1.0.6 (PubChem release 2021.10.14)

2.1.3 InChIKey

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

2.1.4 SMILES

O=[Mg]
Computed by OEChem 2.3.0 (PubChem release 2024.12.12)

2.2 Molecular Formula

MgO
Computed by PubChem 2.2 (PubChem release 2021.10.14)

2.3 Other Identifiers

2.3.1 CAS

1309-48-4

2.3.2 Deprecated CAS

1193320-89-6, 13589-16-7, 185461-91-0, 187036-80-2, 227961-49-1, 2408628-73-7, 52933-73-0, 82375-77-7

2.3.3 European Community (EC) Number

215-171-9

2.3.4 ChEMBL ID

2.3.5 DrugBank ID

2.3.6 HMDB ID

2.3.7 ICSC Number

2.3.8 KEGG ID

2.3.9 NCI Thesaurus Code

2.3.10 PharmGKB ID

2.3.11 RTECS Number

2.3.12 RXCUI

2.3.13 Wikidata

2.3.14 Wikipedia

2.4 Synonyms

2.4.1 MeSH Entry Terms

  • Magnesia
  • Magnesium Oxide
  • Oxide, Magnesium

2.4.2 Depositor-Supplied Synonyms

3 Chemical and Physical Properties

3.1 Computed Properties

Property Name
Molecular Weight
Property Value
40.305 g/mol
Reference
Computed by PubChem 2.2 (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
1
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
39.9799563 Da
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
Monoisotopic Mass
Property Value
39.9799563 Da
Reference
Computed by PubChem 2.2 (PubChem release 2021.10.14)
Property Name
Topological Polar Surface Area
Property Value
17.1 Ų
Reference
Computed by Cactvs 3.4.8.18 (PubChem release 2021.10.14)
Property Name
Heavy Atom Count
Property Value
2
Reference
Computed by PubChem
Property Name
Formal Charge
Property Value
0
Reference
Computed by PubChem
Property Name
Complexity
Property Value
2
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

Magnesium oxide appears as a white solid, often found as a powder. When fine particles of magnesium oxide are dispersed in air, whether directly or when generated by the burning or cutting of magnesium metal, the resulting magnesium oxide fume is an inhalation hazard.
A very bulky, white powder known as light magnesium oxide or a relative dense, white powder known as heavy magnesium oxide. 5 g of light magnesium oxide occupy a volume of at least 33 ml, while 5 g of heavy magnesium oxide occupy a volume of not more than 20 ml
Finely divided white particulate dispersed in air; Note: Exposure may occur when magnesium is burned, thermally cut, or welded upon; [NIOSH]
Solid
HYGROSCOPIC FINE WHITE POWDER.
Finely divided white particulate dispersed in air. [Note: Exposure may occur when magnesium is burned, thermally cut, or welded upon.]

3.2.2 Color / Form

White, very fine powder
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 983
White powder, either light or heavy depending upon whether it is prepared by heating magnesium carbonate or the basic magnesium carbonate
Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 779
Colorless, transparent cubic crystals
Patnaik P; Handbook of Inorganic Chemicals. New York, NY: McGraw-Hill p. 529 (2003)

3.2.3 Odor

Odorless
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 983

3.2.4 Boiling Point

6512 °F at 760 mmHg (NIOSH, 2024)
3,600 °C
Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 4-74
3600 °C
6512 °F

3.2.5 Melting Point

5072 °F (NIOSH, 2024)
2825 °C
Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 4-74
2800 °C
5072 °F

3.2.6 Solubility

0.009 % at 86 °F (NIOSH, 2024)
Practically insoluble in water. Insoluble in ethanol
Soluble in acids and ammonium salt solutions
Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 779
Insoluble in ethanol
Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 4-74
In water, 86 mg/L at 30 °C
Patnaik P; Handbook of Inorganic Chemicals. New York, NY: McGraw-Hill p. 529 (2003)
Solubility in water: poor
(86 °F): 0.009%

3.2.7 Density

3.58 (NIOSH, 2024) - Denser than water; will sink
3.6 g/cu cm
Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 4-74
Relative density (water = 1): 3.6
3.58

3.2.8 Vapor Pressure

0 mmHg (approx) (NIOSH, 2024)
0 mmHg (approx)

3.2.9 pH

pH = 10.3 (saturated aqueous solution)
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 983

3.2.10 Refractive Index

Index of refraction: 1.7355 at 589 nm; 1.7283 at 750 nm
Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 10-241

3.2.11 Other Experimental Properties

Takes up carbon dioxide and water from air, light form more readily than heavy; combines with water to form magnesium hydroxide; imparts a slight alkaline reaction to water
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 983
Moisture sensitive /hygroscopic/
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 2268
Specific heat: 0.92885 kJ/kg-K at 27 °C; heat of fusion: 77.4 kJ/mol at 2642 °C; heat of formation: -601.7 kJ/mol at 25 °C; free energy of formation: -569.44 kJ/mol at 25 °C; Mohs' hardness: 5.5-6.0
Kirk-Othmer Encyclopedia of Chemical Technology. 4th ed. Volumes 1: New York, NY. John Wiley and Sons, 1991-Present., p. V15: 704 (1995)
For more Other Experimental Properties (Complete) data for MAGNESIUM OXIDE (7 total), please visit the HSDB record page.

3.3 Chemical Classes

Other Classes -> Salts, Basic

3.3.1 Drugs

3.3.1.1 Human Drugs
Breast Feeding; Lactation; Milk, Human; Cathartics; Gastrointestinal Agents; Magnesium Compounds; Minerals
Human drug -> Active ingredient (MAGNESIUM OXIDE)

3.3.2 Food Additives

ANTICAKING AGENT OR FREE-FLOW AGENT, DRYING AGENT, FLAVOR ENHANCER, FLAVORING AGENT OR ADJUVANT, FORMULATION AID, HUMECTANT, NUTRIENT SUPPLEMENT, PH CONTROL AGENT, PROCESSING AID -> FDA Substance added to food

4 Spectral Information

4.1 Mass Spectrometry

4.1.1 Other MS

Other MS
IN PRESENCE OF LIMITED AMT OF WATER SETS TO MASS OF CEMENT-LIKE HARDNESS

4.2 UV Spectra

Highly reflective in visible and near UV region
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 983

4.3 IR Spectra

4.3.1 FTIR Spectra

1 of 2
Technique
KBr WAFER
Source of Spectrum
SRL
Source of Sample
E. MERCK AG, DARMSTADT, GERMANY
Copyright
Copyright © 1980, 1981-2024 John Wiley & Sons, Inc. All Rights Reserved.
Thumbnail
Thumbnail
2 of 2
Technique
KBr WAFER
Source of Sample
Mallinckrodt Inc., St. Louis, Missouri
Copyright
Copyright © 1980, 1981-2024 John Wiley & Sons, Inc. All Rights Reserved.
Thumbnail
Thumbnail

4.3.2 ATR-IR Spectra

1 of 2
Source of Sample
Aldrich
Catalog Number
203718
Copyright
Copyright © 2018-2024 Sigma-Aldrich Co. LLC. - Database Compilation Copyright © 2018-2024 John Wiley & Sons, Inc. All Rights Reserved.
Thumbnail
Thumbnail
2 of 2
Source of Sample
Sigma-Aldrich
Catalog Number
307742
Copyright
Copyright © 2018-2024 Sigma-Aldrich Co. LLC. - Database Compilation Copyright © 2018-2024 John Wiley & Sons, Inc. All Rights Reserved.
Thumbnail
Thumbnail

6 Chemical Vendors

7 Drug and Medication Information

7.1 Drug Indication

Indicated for over-the-counter use as a supplement for cardiovascular and neuromuscular health, and as an antacid for relief of acid indigestion and upset stomach. Magnesium oxide, in combination with sodium picosulfate and anhydrous citric acid, is indicated for cleansing of the colon as a preparation for colonoscopy in adults and pediatric patients ages 9 years and older.

7.2 Drug Classes

Breast Feeding; Lactation; Milk, Human; Cathartics; Gastrointestinal Agents; Magnesium Compounds; Minerals

7.3 FDA Approved Drugs

7.4 FDA Orange Book

7.5 FDA National Drug Code Directory

7.6 Drug Labels

Drug and label
Active ingredient and drug
Homeopathic product and label

7.7 Clinical Trials

7.7.1 ClinicalTrials.gov

7.7.2 EU Clinical Trials Register

7.8 Therapeutic Uses

Antacids; Cathartics
National Library of Medicine's Medical Subject Headings online file (MeSH, 1999)
Antacid; relieves acid indigestion, upset stomach
US Natl Inst Health; DailyMed. Current Medication Information for MAGNESIUM OXIDE tablet (September 2010). Available from, as of November 8, 2011: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=30599
Medication (Vet): For oral administration as an aid in the treatment of digestive disturbances requiring an antacid or a mild laxative in cattle.
US Natl Inst Health; DailyMed. Current Medication Information for MAGMILAX BOLUS (magnesium oxide) tablet (December 2009). Available from, as of November 8, 2011: https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=890f2da6-b228-4015-a1f0-24d4edddc2fb
A 14-yr-old female underwent exploratory laparotomy for an abdominal mass, and a diagnosis of Burkitt's lymphoma was made. Postoperatively, she was started on large-dose methotrexate. She developed tumor lysis syndrome and subsequent renal failure, for which she was placed on hemodialysis. ... She started having a burning sensation in her soles and palm 3 days after initiation of methotrexate treatment. The pain management service was consulted, and her Faces pain scale score was noted to be 4/5 and her visual analog scale score was 8/10. She was started on IV fentanyl patient-controlled analgesia. Despite escalating adjustments to her dose, she continued to have severe pain with mechanical allodynia and hyperalgesia. ... The addition of an N-methyl-d-aspartic acid (NMDA)-receptor antagonist was considered and oral magnesium oxide 100 mg was administered once a day. Two days later, with no further escalation of her fentanyl patientcontrolled analgesia, her symptoms were significantly improved. Her visual analog scale score improved to 3/10 and her Faces pain scale score was 2/5. There were no side effects, including diarrhea, from the use of magnesium. The burning sensation decreased and her allodynia and hyperalgesia diminished. She was weaned off the fentanyl and discharged home on oral opioids and magnesium oxide. ...
Suresh S et al; Anesth Analg. 96 (5): 1413-4 (2003)
For more Therapeutic Uses (Complete) data for MAGNESIUM OXIDE (18 total), please visit the HSDB record page.

7.9 Drug Warnings

Magnesium-containing antacids commonly cause a laxative effect and frequent administration of these antacids alone often cannot be tolerated; repeated doses cause diarrhea which may cause fluid and electrolyte imbalances. ... /Magnesium containing antacids/
American Society of Health-System Pharmacists 2011; Drug Information 2011. Bethesda, MD. 2011
In patients with severe renal impairment, hypermagnesemia characterized by hypotension, nausea, vomiting, ECG changes, respiratory or mental depression, and coma has occurred after administration of magnesium-containing antacids. Magnesium-containing antacids should not be administered in patients with renal failure, and antacid products containing more than 50 mEq of magnesium in the recommended daily dosage should be used cautiously and only under the supervision of a physician who should monitor electrolytes in patients with renal disease. /Magnesium containing antacids/
American Society of Health-System Pharmacists 2011; Drug Information 2011. Bethesda, MD. 2011

7.10 Reported Fatal Dose

3= MODERATELY TOXIC: PROBABLE ORAL LETHAL DOSE (HUMAN) 0.5-5 G/KG, BETWEEN 1 OZ OR 1 PINT (OR 1 LB) FOR 70 KG PERSON (150 LB) (based on data described by authors as obviously inadequate).
Gosselin, R.E., R.P. Smith, H.C. Hodge. Clinical Toxicology of Commercial Products. 5th ed. Baltimore: Williams and Wilkins, 1984., p. II-127

8 Food Additives and Ingredients

8.1 Food Additive Classes

JECFA Functional Classes
Food Additives -> ANTICAKING_AGENT;

8.2 FDA Substances Added to Food

Used for (Technical Effect)
ANTICAKING AGENT OR FREE-FLOW AGENT, DRYING AGENT, FLAVOR ENHANCER, FLAVORING AGENT OR ADJUVANT, FORMULATION AID, HUMECTANT, NUTRIENT SUPPLEMENT, PH CONTROL AGENT, PROCESSING AID

8.3 Color Additive Status

Color Additive
Use
None
Former Use
formerly Cosmetics
Other regulations in 21 eCFR

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

Chemical Name
MAGNESIUM OXIDE
Evaluation Year
1965
ADI
NOT LIMITED

9 Minerals

Formula
MgO
System
Cubic

10 Pharmacology and Biochemistry

10.1 MeSH Pharmacological Classification

Antacids
Substances that counteract or neutralize acidity of the GASTROINTESTINAL TRACT. (See all compounds classified as Antacids.)

10.2 FDA Pharmacological Classification

1 of 3
Non-Proprietary Name
MAGNESIA OXYDATA
Pharmacological Classes
Osmotic Laxative [EPC]; Magnesium Ion Exchange Activity [MoA]; Calculi Dissolution Agent [EPC]; Increased Large Intestinal Motility [PE]; Stimulation Large Intestine Fluid/Electrolyte Secretion [PE]; Inhibition Small Intestine Fluid/Electrolyte Absorption [PE]; Inhibition Large Intestine Fluid/Electrolyte Absorption [PE]; Osmotic Activity [MoA]
2 of 3
Non-Proprietary Name
MAGNESIUM OXIDE
Pharmacological Classes
Osmotic Laxative [EPC]; Magnesium Ion Exchange Activity [MoA]; Osmotic Activity [MoA]; Inhibition Large Intestine Fluid/Electrolyte Absorption [PE]; Inhibition Small Intestine Fluid/Electrolyte Absorption [PE]; Calculi Dissolution Agent [EPC]; Increased Large Intestinal Motility [PE]; Stimulation Large Intestine Fluid/Electrolyte Secretion [PE]
3 of 3
Non-Proprietary Name
MAGNESIUM OXIDE 400MG
Pharmacological Classes
Magnesium Ion Exchange Activity [MoA]; Osmotic Laxative [EPC]; Stimulation Large Intestine Fluid/Electrolyte Secretion [PE]; Increased Large Intestinal Motility [PE]; Calculi Dissolution Agent [EPC]; Inhibition Small Intestine Fluid/Electrolyte Absorption [PE]; Osmotic Activity [MoA]; Inhibition Large Intestine Fluid/Electrolyte Absorption [PE]

10.3 ATC Code

A - Alimentary tract and metabolism

A12 - Mineral supplements

A12C - Other mineral supplements

A12CC - Magnesium

A12CC10 - Magnesium oxide

A - Alimentary tract and metabolism

A06 - Drugs for constipation

A06A - Drugs for constipation

A06AD - Osmotically acting laxatives

A06AD02 - Magnesium oxide

A - Alimentary tract and metabolism

A02 - Drugs for acid related disorders

A02A - Antacids

A02AA - Magnesium compounds

A02AA02 - Magnesium oxide

10.4 Bionecessity

Magnesium is an essential mineral that helps maintain normal muscle and nerve function, keeps the heart rhythm steady, and helps the bones strong. It is also involved in energy metabolism and protein synthesis. Magnesium deficiency may cause metabolic changes that contribute to heart attacks and strokes and may be a risk factor for postmenopausal osteoporosis. About half the body's magnesium stores are found inside the cells of body tissues and organs, and half are combined with calcium and phosphorus in the bone. Only 1% is found in the blood. The Recommended Dietary allowance for magnesium for adults ranges from 310 to 420 mg depending on life-stage and sex.[NIH, Facts about Dietary Supplements: Magnesium. NIH Clinical Center, Natl Inst Health

10.5 Absorption, Distribution and Excretion

The elimination of magnesite dust /(MgO 88.52%, Fe2O3 7.57%, CaO 2.74%, Al2O3 0.49%, SiO2 0.68%)/ from the lung was examined on Wistar rats after a single exposure (6 hr) and repeated exposure to dust (200 hr) ... After a single exposure magnesite dust was eliminated as the silica dust with an intermediate fibrogenic effect, 41% of deposited dust being eliminated. Following long-term exposure, the ability to eliminate dust diminished by 20.1% ...Serum magnesium increased moderately during exposure and returned to the initial level 25 days after the end of the exposure. There was a significant increase in magnesium excretion with urine. The findings showed that inhaled dust was gradually dissolved in the body. The magnesium content was evaluated in the reticuloendothelial organs (liver and spleen) 25 days after the last exposure and was found to increase by 20.1% in the spleen and by 15.6% in the liver. A concomitant histological exam of internal organs confirmed that the dust was retained in the lungs (without fibrotic changes), that particles were present in the spleen (sinusoid macrophages) and that the red pulp was hemorrhagic. No signs of pulmonary fibrosis were found even after 6 months after the last exposure. Dust particles were found in thickened interalveolar septa and macrophages. Proliferative histiocytic elements with particles present were found in the subcapsular sinuses and medulla of hilus lymphatic nodes. The findings showed that magnesite dust was eliminated by both blood and lymph. /Magnesite dust/
Reichrtova E, Takac L; J Hyg Epidemiol Microbiol Immunol 36 (4): 235-244 (1992)
INSOLUBLE COMPOUND SUCH AS MgO ARE RETAINED FOR A LONGER PERIOD... MAGNESIUM IS RETAINED IN SKELETON, MUSCLE, AND SOFT TISSUE.
Venugopal, B. and T.D. Luckey. Metal Toxicity in Mammals, 2. New York: Plenum Press, 1978., p. 53
This study was conducted to evaluate the ability of the large intestine to absorb calcium (Ca) and magnesium (Mg) from their sparingly water-soluble salts, and also to determine whether fructooligosaccharides (FOS) stimulate the absorption of these minerals in rat large intestine in vivo. Rats were fed Ca- and Mg-free diets with and without 5% FOS. An aqueous suspension of CaCO3 and MgO was infused into the stomach via a gastric tube or into the cecum via an implanted catheter. Coprophagy was prevented by using wire-mesh anal cups throughout the experiment so as to exclude the re-ingestion of feces as an oral mineral source. In rats fed an FOS-free diet, the absorption degrees of Ca and Mg infused into the cecum were the same as those infused into the stomach. The absorption degree of phosphorus (P) was slightly but significantly higher in rats with the infusion of Ca and Mg into the cecum than in rats with the infusion of Ca and Mg into the stomach. FOS-feeding increased the absorption of Mg to a similar extent in either case of infusion via cecal and oral routes, while FOS-feeding did not increase the absorption of Ca in rats with infusion of Ca and Mg into the cecum. /Researchers/ ... concluded that both CaCO3 and MgO are absorbed in the large intestine, and ... ascertained that the increasing effect of FOS on the absorption of Mg took place mainly in the large intestine.
Ohta A, et al; J Nutr Sci Vitaminol 43 (1): 35-46 (1997)

10.6 Mechanism of Action

The term "Milk of Magnesia" was first used to describe a white aqueous, mildly alkaline suspension of magnesium hydroxide formulated at about 8%w/v. Milk of magnesia is primarily used to alleviate constipation, but can also be used to relieve indigestion and heartburn. When taken internally by mouth as a laxative, the osmotic force of the magnesia suspension acts to draw fluids from the body and to retain those already within the lumen of the intestine, serving to distend the bowel, thus stimulating nerves within the colon wall, inducing peristalsis and resulting in evacuation of colonic contents. Magnesium supplements have also been shown to reduce platelet aggregation by inhibiting in the influx of calcium, a crucial component of platelet aggregation.

11 Use and Manufacturing

11.1 Uses

Sources/Uses
Used in medications, animal feeds, fertilizers, insulation, wallboard, electrical heating rods, crucibles, fire bricks, petroleum additives, boiler scale control agents, and food additives; [HSDB]
Industrial Processes with risk of exposure
Farming (Feed Additives) [Category: Industry]
Both oil base and water base fracturing fluids are being used in the fracturing industry. Water base, which includes alcohol-water mixtures and low strength acids, make up the majority of treating fluids. The common chemicals added to these fluids are polymers for viscosity development, crosslinkers for viscosity enhancement, pH control chemicals, gel breakers for polymer degradation following the treatment, surfactants, clay stabilizers, alcohol, bactericides, fluid loss additives and friction reducer. /Hydraulic fracturing/
Halliburton; Hydraulic Fracturing. Document ID: EPA-HQ-ORD-2010-0674-1634 p.32. Available from, as of October 27, 2011: https://www.regulations.gov/#!documentDetail;D=EPA-HQ-ORD-2010-0674-1634
Hydraulic fracturing uses a specially blended liquid which is pumped into a well under extreme pressure causing cracks in rock formations underground. These cracks in the rock then allow oil and natural gas to flow, increasing resource production. ... Chemical Name: Magnesium oxide; Chemical Purpose: Allows a delayed break down of the gel; Product Function: Breaker.
FracFocus; Chemical Disclosure Registry, Hydraulic Fracturing, How it Works; What Chemicals are Used. Available from, as of October 28, 2011: https://fracfocus.org/chemical-use/what-chemicals-are-used
For magnesium oxide (USEPA/OPP Pesticide Code: 009235) there are 0 labels match. /SRP: Not registered for current 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./
U.S. Environmental Protection Agency/Office of Pesticide Program's Chemical Ingredients Database on Magnesium Oxide (1309-48-4). Available from, as of October 23, 2002: https://npirspublic.ceris.purdue.edu/ppis/
CHEM INT MEDICINALS AND OTHER CHEMS; COMPONENT OF ANIMAL FEEDS, FERTILIZERS, INSULATION, AND WALLBOARD; COMPONENT OF PETROLEUM ADDITIVES, OXYCHLORIDE AND OXYSULFATE CEMENT; AGENT IN PULP AND PAPER MFR; FOOD CHEM; RUBBER ACCELERATOR; COMPONENT OF ELECTRICAL HEATING RODS; MISC APPLICATIONS
SRI
For more Uses (Complete) data for MAGNESIUM OXIDE (12 total), please visit the HSDB record page.

11.1.1 Use Classification

Food additives
Human Drugs -> FDA Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book) -> Active Ingredients
Food Additives -> ANTICAKING_AGENT; -> JECFA Functional Classes

11.1.2 Household Products

Household & Commercial/Institutional Products

Information on 37 consumer products that contain Magnesium oxide in the following categories is provided:

• Auto Products

• Home Maintenance

• Inside the Home

• Landscaping/Yard

• Personal Care

• Pesticides

11.2 Methods of Manufacturing

... /Dolomitic/ limestone is calcined at a high temperature under controlled conditions to produce calcined dolomite or dolime which upon reaction with magnesium chloride-rich brine produces magnesium hydroxide and calcium chloride. The insoluble magnesium hydroxide is then separated from the liquid calcium chloride carrier and calcined under controlled conditions. The various grades of magnesia range from very reactive light-burned to nonreactive dead-burned.
Kramer D; Magnesium Compounds. Kirk-Othmer Encyclopedia of Chemical Technology (1999-2011). John Wiley & Sons, Inc. Online Posting Date: June 18, 2004
... Mining, crushing, sizing, and subsequent calcination of natural magnesite. The chemical purity of the magnesia produced is dependent on the mineralogical composition of the natural magnesite.
Kramer D; Magnesium Compounds. Kirk-Othmer Encyclopedia of Chemical Technology (1999-2011). John Wiley & Sons, Inc. Online Posting Date: June 18, 2004
A concentrated magnesium chloride brine processed from the Dead Sea is sprayed into a reactor at about 1700 °C. The brine is thermally decomposed into magnesium oxide and hydrochloric acid. To further process the magnesia, the product is slaked to form magnesium hydroxide which is then washed, filtered, and calcined under controlled conditions to produce a variety of magnesium oxide reactivity grades.
Kramer D; Magnesium Compounds. Kirk-Othmer Encyclopedia of Chemical Technology (1999-2011). John Wiley & Sons, Inc. Online Posting Date: June 18, 2004
The seawater process ... involves decarbonating limestone or dolomite to the point where all CO2 is removed without converting the resulting magnesia to a chemically inactive form. Reaction of filtered seawater, treated to remove bicarbonate and/or sulfate, and dolime is followed by seeding with magnesium hydroxide to promote crystal growth. Upon formation of magnesium hydroxide, flocculants are added and the magnesium hydroxide precipitate is allowed to settle while the spent seawater is disposed to the sea. The precipitate is washed, filtered, and dried to obtain magnesium hydroxide which is calcined to produce light-burned, hard-burned, or dead-burned magnesium oxide.
Kramer D; Magnesium Compounds. Kirk-Othmer Encyclopedia of Chemical Technology (1999-2011). John Wiley & Sons, Inc. Online Posting Date: June 18, 2004
Light or heavy magnesium carbonate is exposed to red heat, whereupon CO2 and H2O are expelled, and light or heavy magnesium oxide is left. The density of the oxide also is influenced by the calcining temperature; high temperature yielding more compact forms.
Troy, D.B. (Ed); Remmington The Science and Practice of Pharmacy. 21 st Edition. Lippincott Williams & Williams, Philadelphia, PA 2005, p. 1296

11.3 Impurities

TRACE IMPURITIES: NaCl, KCl, NaF
KIRK-OTHMER ENCYC CHEM TECH 3RD ED 1978-PRESENT V14 p.630

11.4 Formulations / Preparations

The principal commercial forms of magnesia are dead-burned magnesia (periclase), caustic-calcined (light-burned magnesia), hard-burned magnesia, and calcined dolomite.
Kramer D; Magnesium Compounds. Kirk-Othmer Encyclopedia of Chemical Technology (1999-2011). John Wiley & Sons, Inc. Online Posting Date: June 18, 2004
Table: Magnesium Oxide Preparations
Route of Administration
Bulk
Dosage Form
Powder
Brand or Generic Name (Manufacturer)
(Available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name)
Route of Administration
Oral
Dosage Form
Capsules
Strength
140 mg
Brand or Generic Name (Manufacturer)
Uro-Mag (Blaine)
Route of Administration
Oral
Dosage Form
Tablets
Strength
400 mg
Brand or Generic Name (Manufacturer)
Magnesium Oxide Tablets (Available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name)
Route of Administration
Oral
Dosage Form
Tablets
Strength
400 mg
Brand or Generic Name (Manufacturer)
Mag-Ox 400 (Blaine)
Route of Administration
Oral
Dosage Form
Tablets
Strength
420 mg
Brand or Generic Name (Manufacturer)
Magnesium Oxide Tablets (Available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name)
American Society of Health-System Pharmacists 2011; Drug Information 2011. Bethesda, MD. 2011

11.5 Consumption Patterns

20% IS USED IN CHEMICAL MANUFACTURING; 18% IN ANIMAL FEED AND FERTILIZER; 16% FOR MEDICINALS, INSULATION AND WALLBOARD, FLUX, AND PETROLEUM ADDITIVES; 14% FOR OXYCHLORIDE AND OXYSULFATE CEMENT; 12% FOR PULP AND PAPER MANUFACTURING; 6% AS A RUBBER ACCELERATOR; 4% USED IN FOODS; 2% IN ELECTRICAL HEATING RODS; 8% FOR UNSPECIFIED USES (1972)
SRI
CHEMICAL GRADE ONLY-DERIVATIVE: ANIMAL FEEDS AND FERTILIZERS, 35%; MEDICINALS, SUGAR & WINE MAKING, 4%; CONSTRUCTION MATERIALS, 5%; PULP, PAPER AND RAYON, 18%; RUBBER, 8%; PETROLEUM ADDITIVES, 15%; MISC, 15% (1981)
CHEMICAL PRODUCTS SYNOPSIS: MAGNESIUM OXIDE, 1981
/MAGNESIUM COMPOUNDS/ PRODUCTION OF BASIC REFRACTORIES USED IN HIGH-TEMP METALLURGICAL FURNACES, 80%; AND PREP OF CAUSTIC CALCINED & SPECIFIED MAGNESIA, 20% (1985)
BUREAU OF MINES. MINERAL COMMODITY SUMMARIES 1986 p.96

11.6 U.S. Production

(1972) 1.82X10+11 GRAMS (MAGNESIA)
SRI
Production volumes for non-confidential chemicals reported under the Inventory Update Rule.
Year
1986
Production Range (pounds)
>50 million - 100 million
Year
1990
Production Range (pounds)
No Reports
Year
1994
Production Range (pounds)
No Reports
Year
1998
Production Range (pounds)
No Reports
Year
2002
Production Range (pounds)
10 thousand - 500 thousand
US EPA; Non-confidential Production Volume Information Submitted by Companies for Chemicals Under the 1986-2002 Inventory Update Rule (IUR). Magnesium oxide (1309-48-4). Available from, as of October 11, 2011: https://www.epa.gov/oppt/iur/tools/data/2002-vol.html
Production volume for non-confidential chemicals reported under the 2006 Inventory Update Rule. Chemical: Magnesium oxide. Aggregated National Production Volume: 500 million to < 1 billion pounds.
US EPA; Non-Confidential 2006 Inventory Update Reporting. National Chemical Information. Magnesium oxide (1309-48-4). Available from, as of October 11, 2011: https://cfpub.epa.gov/iursearch/index.cfm?s=chem&err=t

11.7 U.S. Imports

(1972) 4.91X10+10 GRAMS (MAGNESIA, MAGNESITE)
SRI
(1975) 3.27X10+8 GRAMS
SRI

11.8 U.S. Exports

(1972) 2.62X10+8 GRAMS
SRI

11.9 General Manufacturing Information

Available in a very bulky form termed "Light" or in a dense form termed "Heavy"
O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 983
Light magnesia is preferable to heavy for admin in liquids because, being finer powder, it suspends more readily.
Troy, D.B. (Ed); Remmington The Science and Practice of Pharmacy. 21 st Edition. Lippincott Williams & Williams, Philadelphia, PA 2005, p. 1296
ASBESTOS.../CONTAINS/ SILICA AND MAGNESIUM OXIDE IN LARGE AMT AND TRACES OF IRON, CHROMIUM, CADMIUM, AND ZINC...
Luckey, T.D. and B. Venugopal. Metal Toxicity in Mammals, 1. New York: Plenum Press, 1977., p. 107
Two forms are produced, one a light, fluffy material prepared by a relatively low-temperature dehydration of the hydroxide, the other a dense material mede by high-temperature furnacing of the oxide after it has been formed from the carbonate or hydroxide. /periclase/
Thomson/Micromedex. Drug Information for the Health Care Professional. Volume 1, Greenwood Village, CO. 2007.

12 Safety and Hazards

12.1 Hazards Identification

12.1.1 GHS Classification

1 of 2
View All
GHS Hazard Statements

Not Classified

Reported as not meeting GHS hazard criteria by 1569 of 1790 companies

ECHA C&L Notifications Summary

Aggregated GHS information provided per 1790 reports by companies from 23 notifications to the ECHA C&L Inventory.

Reported as not meeting GHS hazard criteria per 1569 of 1790 reports by companies. For more detailed information, please visit ECHA C&L website.

There are 20 notifications provided by 221 of 1790 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.

12.1.2 Hazard Classes and Categories

Not Classified

Serious eye damage/eye irritation - Category 2

Specific target organ toxicity - Single exposure - Category 3 (Respiratory tract irritation)

12.1.3 Health Hazards

Excerpt from NIOSH Pocket Guide for Magnesium oxide fume:

Exposure Routes: Inhalation, skin and/or eye contact

Symptoms: Irritation eyes, nose; metal fume fever: cough, chest pain, flu-like fever

Target Organs: Eyes, respiratory system (NIOSH, 2024)

12.1.4 Fire Hazards

Not combustible.

12.1.5 Hazards Summary

Fumes of zinc, copper, and magnesium can cause metal fume fever. [LaDou, p. 376] A skin and eye irritant; May be harmful if swallowed or inhaled; [Sigma-Aldrich MSDS]
LaDou - LaDou J, Harrison R (eds). Current Occupational & Environmental Medicine, 5th Ed. New York: McGraw-Hill, 2014., p. 376

12.1.6 Skin, Eye, and Respiratory Irritations

Irritates the eyes and respiratory tract. Magnesium in the form of nascent magnesium oxide can cause metal fume fever with cough, chest pain, and flu like fever, if inhaled in sufficient quantity. The symptoms of metal fume fever may be delayed for 4-12 hr following exposure.
Sittig, M. Handbook of Toxic and Hazardous Chemicals and Carcinogens, 2002. 4th ed.Vol 1 A-H Norwich, NY: Noyes Publications, 2002., p. 1427
Examination of 95 workers exposed to an unspecified concentration of MgO dust revealed slight iritation of the eyes and nose. ... Conjunctivitis, nasal catarrh, and coughing up discolored sputum /was cited/ after industrial exposures, but even when such exposures doubled serum magnesium as compared to normal concentrations, no systematic effects were noted amoung these workers; however, serum calcium concentrations were elevated.
American Conference of Governmental Industrial Hygienists. Documentation of Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices for 2001. Cincinnati, OH. 2001., p. 1

12.2 Safety and Hazard Properties

12.2.1 Flammable Limits

Flammability
Noncombustible Solid

12.2.2 OSHA Standards

Permissible Exposure Limit: Table Z-1 8 hour Time Weighted Avg: 15 mg/cu m (total particulate). /Magnesium oxide fume/
29 CFR 1910.1000 (USDOL); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011August 30, 2011: https://www.ecfr.gov

12.2.3 NIOSH Recommendations

After reviewing available published literature, NIOSH provided comments to OSHA on August 1, 1988, regarding the "Proposed Rule on Air Contaminants" (29 CFR 1910, Docket No. H-020) ... At that time, NIOSH also conducted a limited evaluation of the literature and concluded that the documentation cited by OSHA was inadequate to support the proposed PEL (as an 8-hour TWA) of 10 mg/cu m for ... magnesium oxide fume ... .
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)

12.3 First Aid Measures

Inhalation First Aid
Fresh air, rest.
Skin First Aid
Remove contaminated clothes. Rinse and then wash skin with water and soap.
Eye First Aid
Rinse with plenty of water (remove contact lenses if easily possible).
Ingestion First Aid
Rinse mouth.

12.3.1 First Aid

Excerpt from NIOSH Pocket Guide for Magnesium oxide fume:

Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible. (NIOSH, 2024)

(See general first aid procedures)

Breathing: Respiratory support

12.4 Fire Fighting

In case of fire in the surroundings: all extinguishing agents allowed.

12.5 Accidental Release Measures

12.5.1 Spillage Disposal

Personal protection: particulate filter respirator adapted to the airborne concentration of the substance. Sweep spilled substance into covered containers. If appropriate, moisten first to prevent dusting.

12.5.2 Disposal Methods

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

12.5.3 Preventive Measures

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

12.6 Handling and Storage

12.6.1 Safe Storage

Separated from strong acids. Dry. Well closed.

12.6.2 Storage Conditions

Store in tightly closed containers in a cool, well ventilated area away from moisture.
Sittig, M. Handbook of Toxic and Hazardous Chemicals and Carcinogens, 2002. 4th ed.Vol 1 A-H Norwich, NY: Noyes Publications, 2002., p. 1427

12.7 Exposure Control and Personal Protection

Maximum Allowable Concentration (MAK)
4.0 [mg/m3], (inhalable fraction), 0.3 mg/m3 (respirable fraction, multiplied with the material density)[German Research Foundation (DFG)]

12.7.2 Permissible Exposure Limit (PEL)

15.0 [mg/m3], total particulate (fume)
TWA 15 mg/m3 See Appendix G

12.7.3 Immediately Dangerous to Life or Health (IDLH)

750 mg/m3 [From NPG: Magnesium oxide fume] (NIOSH, 2024)

750.0 [mg/m3]

Excerpts from Documentation for IDLHs: Volunteers exposed to freshly generated fume at concentrations ranging from 410 to 580 mg/m3 experienced only slight (unspecified) reactions [Drinker et al. 1927].

750 mg/cu m
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)

750 mg/m3

See: 1309484

12.7.4 Threshold Limit Values (TLV)

10.0 [mg/m3], inhalable fraction
8 hr Time Weighted Avg (TWA): 10 mg/cu m (Inhalable fraction).
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 37
Excursion Limit Recommendation: Excursions in worker exposure levels may exceed 3 times the TLV-TWA for no more than a total of 30 minutes during a work day, and under no circumstances should they exceed 5 times the TLV-TWA, provided that the TLV-TWA is not exceeded.
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 5
A4; Not classifiable as a human carcinogen.
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 37
(inhalable fraction): 10 mg/m

12.7.5 Occupational Exposure Limits (OEL)

MAK (Maximale Arbeitsplatz Konzentration)
(inhalable fraction): 4 mg/m

12.7.6 Inhalation Risk

A nuisance-causing concentration of airborne particles can be reached quickly when dispersed.

12.7.7 Effects of Short Term Exposure

May cause mechanical irritation.

12.7.8 Effects of Long Term Exposure

Lungs may be affected by repeated or prolongated exposure to dust particles.

12.7.9 Allowable Tolerances

Residues of magnesium oxide are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops or to raw agricultural commodities after harvest. Use: solid diluent, carrier. Limit: none.
40 CFR 180.910 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Residues of the following chemical substances are exempted from the requirement of a tolerance when used in accordance with good manufacturing practice as ingredients in an antimicrobial pesticide formulation, provided that the substance is applied on a semi-permanent or permanent food-contact surface (other than being applied on food packaging) with adequate draining before contact with food. (a) The following chemical substances when used as ingredients in an antimicrobial pesticide formulation may be applied to: Food-contact surfaces in public eating places, dairy-processing equipment, and food-processing equipment and utensils. Magnesium oxide is included on this list.
40 CFR 180.940(a) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Residues of the following chemical substances are exempted from the requirement of a tolerance when used in accordance with good manufacturing practice as ingredients in an antimicrobial pesticide formulation, provided that the substance is applied on a semi-permanent or permanent food-contact surface (other than being applied on food packaging) with adequate draining before contact with food. ... (c) The following chemical substances when used as ingredients in an antimicrobial pesticide formulation may be applied to: Food-processing equipment and utensils. Magnesium oxide is included on this list.
40 CFR 180.940(c) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov

12.7.10 Personal Protective Equipment (PPE)

Excerpt from NIOSH Pocket Guide for Magnesium oxide fume:

Skin: No recommendation is made specifying the need for personal protective equipment for the body.

Eyes: No recommendation is made specifying the need for eye protection.

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: No recommendation is made specifying the need for removing clothing that becomes wet or contaminated.

Change: No recommendation is made specifying the need for the worker to change clothing after the workshift. (NIOSH, 2024)

Respirator Recommendations: Up to 150 mg/cu m:
Assigned Protection Factor (APF)
APF = 10
Respirator Recommendations
Any particulate respirator equipped with an N95, R95, or P95 filter (including N95, R95, and P95 filtering facepieces) except quarter-mask respirators. The following filters may also be used: N99, R99, P99, N100, R100, P100.
Assigned Protection Factor (APF)
APF = 10
Respirator Recommendations
Any supplied-air respirator.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Respirator Recommendations: Up to 375 mg/cu m:
Assigned Protection Factor (APF)
APF = 25
Respirator Recommendations
Any supplied-air respirator operated in a continuous-flow mode.
Assigned Protection Factor (APF)
APF = 25
Respirator Recommendations
Any powered, air-purifying respirator with a high-efficiency particulate filter.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Respirator Recommendations: Up to 750 mg/cu m:
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendations
Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendations
Any powered, air-purifying respirator with a tight-fitting facepiece and a high-efficiency particulate filter. Substance reported to cause eye irritation or damage; may require eye protection.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendations
Any self-contained breathing apparatus with a full facepiece.
Assigned Protection Factor (APF)
APF = 50
Respirator Recommendations
Any supplied-air respirator with a full facepiece.
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
Respirator Recommendations: Emergency or planned entry into unknown concentrations or IDLH conditions:
Assigned Protection Factor (APF)
APF = 10,000
Respirator Recommendations
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 Recommendations
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 & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005)
For more Personal Protective Equipment (PPE) (Complete) data for MAGNESIUM OXIDE (7 total), please visit the HSDB record page.

(See personal protection and sanitation codes)

Skin: No recommendation

Eyes: No recommendation

Wash skin: No recommendation

Remove: No recommendation

Change: No recommendation

12.7.11 Respirator Recommendations

OSHA

Up to 150 mg/m3 :

(APF = 10) Any particulate respirator equipped with an N95, R95, or P95 filter (including N95, R95, and P95 filtering facepieces) except quarter-mask respirators. The following filters may also be used: N99, R99, P99, N100, R100, P100.

Click here for information on selection of N, R, or P filters.

(APF = 10) Any supplied-air respirator

Up to 375 mg/m3 :

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

(APF = 25) Any powered, air-purifying respirator with a high-efficiency particulate filter.

Up to 750 mg/m3 :

(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter.

Click here for information on selection of N, R, or P filters.

(APF = 50) Any powered, air-purifying respirator with a tight-fitting facepiece and a high-efficiency particulate filter*

(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 with an N100, R100, or P100 filter.

Click here for information on selection of N, R, or P filters.

Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

12.7.12 Preventions

Fire Prevention
NO contact with strong acids.
Exposure Prevention
PREVENT DISPERSION OF DUST!
Inhalation Prevention
Use local exhaust or breathing protection.
Skin Prevention
Protective gloves.
Eye Prevention
Wear safety goggles or eye protection in combination with breathing protection.
Ingestion Prevention
Do not eat, drink, or smoke during work.

12.8 Stability and Reactivity

12.8.1 Air and Water Reactions

No rapid reaction with air. No rapid reaction with water.

12.8.2 Reactive Group

Salts, Basic

12.8.3 Reactivity Profile

Phosphorus pentachloride and magnesium oxide react with brilliant incandescence [Mellor 8:1016. 1946-1947]. The oxide is incompatible with interhalogens such as bromine pentafluoride, etc.

12.8.4 Hazardous Reactivities and Incompatibilities

Violent reaction with halogens, chlorine trifluoride, bromine pentalfluoride, phosphorous pentachloride, strong acids. May ignite and explode when heated with sublimed sulfur, magnesium powder, or aluminum powder.
Sittig, M. Handbook of Toxic and Hazardous Chemicals and Carcinogens, 2002. 4th ed.Vol 1 A-H Norwich, NY: Noyes Publications, 2002., p. 1427
NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases. U.S. Department of Health & Human Services, Public Health Service, Center for Disease Control & Prevention. DHHS (NIOSH) Publication No. 2001-145 (CD-ROM) August 2001.
/Phosphorus pentachloride and magnesium oxide/ ... react with brilliant incandescence.
National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 491-150
Violent reaction or ignition on contact with interhalogens (e.g., bromine pentafluoride; chlorine trifluoride). Incandescent reaction with phosphorus pentachloride.
Lewis, R.J. Sax's Dangerous Properties of Industrial Materials. 9th ed. Volumes 1-3. New York, NY: Van Nostrand Reinhold, 1996., p. 2081
Chlorine trifluoride reacts violently, producing flame, with ... magnesium oxide ... .
National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 491-55

12.9 Regulatory Information

12.9.1 FIFRA Requirements

Residues of magnesium oxide are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops or to raw agricultural commodities after harvest. Use: solid diluent, carrier. Limit: none.
40 CFR 180.910 (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Residues of the following chemical substances are exempted from the requirement of a tolerance when used in accordance with good manufacturing practice as ingredients in an antimicrobial pesticide formulation, provided that the substance is applied on a semi-permanent or permanent food-contact surface (other than being applied on food packaging) with adequate draining before contact with food. (a) The following chemical substances when used as ingredients in an antimicrobial pesticide formulation may be applied to: Food-contact surfaces in public eating places, dairy-processing equipment, and food-processing equipment and utensils. Magnesium oxide is included on this list.
40 CFR 180.940(a) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Residues of the following chemical substances are exempted from the requirement of a tolerance when used in accordance with good manufacturing practice as ingredients in an antimicrobial pesticide formulation, provided that the substance is applied on a semi-permanent or permanent food-contact surface (other than being applied on food packaging) with adequate draining before contact with food. ... (c) The following chemical substances when used as ingredients in an antimicrobial pesticide formulation may be applied to: Food-processing equipment and utensils. Magnesium oxide is included on this list.
40 CFR 180.940(c) (USEPA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov

12.9.2 FDA Requirements

Antacid products for over-the-counter (OTC) human use. Magnesium oxide is included on the list of magnesium-containing active ingredients.
21 CFR 331.11(g) (7) (USFDA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Drug products containing certain active ingredients offered over-the-counter (OTC) for certain uses. A number of active ingredients have been present in OTC drug products for various uses, as described below. However, based on evidence currently available, there are inadequate data to establish general recognition of the safety and effectiveness of these ingredients for the specified uses: Magnesium oxide is included in weight control drug products.
21 CFR 310.545(a) (20) (USFDA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Substance added directly to human food affirmed as generally recognized as safe (GRAS).
21 CFR 184.1431 (USFDA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Magnesium oxide used as a general purpose food additive in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.
21 CFR 582.1431 (USFDA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov
Magnesium oxide used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.
21 CFR 582.5431 (USFDA); U.S. National Archives and Records Administration's Electronic Code of Federal Regulations. Available from, as of October 7, 2011: https://www.ecfr.gov

13 Toxicity

13.1 Toxicological Information

13.1.1 NIOSH Toxicity Data

13.1.2 Evidence for Carcinogenicity

A4: Not classifiable as a human carcinogen.
American Conference of Governmental Industrial Hygienists; 2011 Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices . Cincinnati, OH 2011, p. 37

13.1.3 Effects During Pregnancy and Lactation

◉ Summary of Use during Lactation

No information is available on the clinical use of magnesium oxide during breastfeeding. However, other magnesium salts have been studied. A study on the use of magnesium hydroxide during breastfeeding found no adverse reactions in breastfed infants. Intravenous magnesium increases milk magnesium concentrations only slightly. Oral absorption of magnesium by the infant is poor, so maternal magnesium hydroxide is not expected to affect the breastfed infant's serum magnesium. Magnesium oxide supplementation during pregnancy might delay the onset of lactation, but it can be taken during breastfeeding and no special precautions are required.

◉ Effects in Breastfed Infants

Fifty mothers who were in the first day postpartum received 15 mL of either mineral oil or an emulsion of mineral oil and magnesium hydroxide equivalent to 900 mg of magnesium hydroxide, although the exact number who received each product was not stated. Additional doses were given on subsequent days if needed. None of the breastfed infants were noted to have any markedly abnormal stools, but all of the infants also received supplemental feedings.

◉ Effects on Lactation and Breastmilk

One mother who received intravenous magnesium sulfate for 3 days for pregnancy-induced hypertension had lactogenesis II delayed until day 10 postpartum. No other specific cause was found for the delay, although a complete work-up was not done. A subsequent controlled clinical trial found no evidence of delayed lactation in mothers who received intravenous magnesium sulfate therapy. Some, but not all, studies have found a trend toward increased time to the first feeding or decreased sucking in infants of mothers treated with intravenous magnesium sulfate during labor because of placental transfer of magnesium to the fetus.

A study in 40 pairs of matched healthy women with vaginally delivered singleton pregnancies, outcome endpoints were compared in those receiving continuous oral magnesium aspartate HCl supplementation mean dose of 459 mg daily (range 365 to 729 mg of magnesium daily) for at least 4 weeks before delivery versus non-supplemented controls. In the magnesium group, significantly fewer women could breastfeed their infants exclusively at discharge (63% vs 80%).

13.1.4 Exposure Routes

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

13.1.5 Symptoms

Inhalation Exposure
Cough.
Eye Exposure
Redness.
irritation eyes, nose; metal fume fever: cough, chest pain, flu-like fever

13.1.6 Target Organs

Eyes, respiratory system

13.1.7 Adverse Effects

ACGIH Carcinogen - Not Classifiable.

13.1.8 Acute Effects

13.1.9 Interactions

...The intratracheal admin of /magnesium/ oxide inhibited lung tumor formation by /benzo(a)pyrene and diethylnitrosamine/.
Chang, L.W. (ed.). Toxicology of Metals. Boca Raton, FL: Lewis Publishers, 1996, p. 290
... A phase I/II study /was conducted/ in patients with advanced non-small-cell lung cancer (NSCLC) to increase the therapeutic index of the cisplatin-irinotecan combination by institution of an anti-late-diarrheal program (ADP). A total of 77 chemotherapy-naive patients with advanced NSCLC were enrolled. The cisplatin dose was fixed at 60 mg /per/ sq m (Day 1). Irinotecan was escalated in 5 mg /sq m increments, starting from 60 mg/ sq m (Days 1 and 8). ADP consisted of oral sodium bicarbonate, magnesium oxide, basic water, and ursodeoxycholic acid, and was administered orally for 4 days with each dose of irinotecan. In the phase I portion, irinotecan pharmacokinetics was also examined. After the recommended dose of irinotecan with ADP was determined, a phase II study was conducted to evaluate the response. Maximum tolerated dose was reached at an irinotecan dose of 80 mg sq m (Grade 4 diarrhoea and neutropenia). Pharmacokinetic studies show that the maximum concentration and the area under the curve of both irinotecan and SN38 (active metabolite of irinotecan) tend to increase in the dose-dependent manner of irinotecan. The phase II portion of the study included 48 patients, who were treated with 75 mg/sq m of irinotecan. Grade 3/4 toxicities included neutropenia in 65%, leucopenia in 33%, and late diarrhea in 6% of the patients. During this treatment, PS did not change in 65% of patients. At the end of the chemotherapy, PS did not decline in 90% of patients. In the phase II portion, a response occurred in 63% (95% confidential interval (CI), 47-76%) of patients. Median time to progression was 19 weeks (95% CI, 15-22 weeks), and median survival was 52 weeks (95% CI, 39-64 weeks). This regimen of irinotecan and cisplatin with ADP resulted in promising efficacy with acceptable toxicity for patients with advanced NSCLC.
Takeda Y et al; Br J Cancer. 93 (12): 1341-9 (2005)
Experiments carried out on C57 BL mice showed marked changes in the acid base balance of animals exposed to chamber magnesite dust inhalation which simultaneously received per os pharmacological doses of sodium salicylate ... Exposed animals had permanently higher urine pH values resulting in impaired formation and secretion of salicylic acid ... Free salicylic acid was accumulated in the liver, and partially, spleen.
Reichrtova E, Takac L; J Hyg Epidemiol Microbiol Immunol 36 (4): 321-329 (1992)
Syrian golden hamsters, 48 animals/group, were administered magnesium oxide by intratracheal instillation at 3 mg/wk for life. Particle size was 90%<25 um, 46%<10 um, 18%<5 um, and 1%<1 um. Necropsy of each lobe of the lung, larynx, trachea, and stem bronchi showed slight metaplasia in the tracheobronchial zone and moderate hyperplasia of the alveolar zone. Benzo[a]pyrene (1 mg/wk) administered in combination with magnesium oxide (2 mg/wk) produced similar premalignant lesions as well as squamous tumors in the upper respiratory tract. In contrast, benzo[a]pyrene administered in combination with talc (64-66% SiO2; 34-36% MgO) produced adenocarcinomas in the lower respiratory tract.
Stenback F et al; Cancer Res Monogr 2: 199-213 (1986)

13.1.10 Antidote and Emergency Treatment

/SRP:/ 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. /Magnesium and Related Compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 403
/SRP:/ 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 ... . Monitor for shock 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 ... . /Magnesium and Related Compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 403
/SRP:/ 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 ... . 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 ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Magnesium and Related Compounds/
Currance, P.L. Clements, B., Bronstein, A.C. (Eds).; Emergency Care For Hazardous Materials Exposure. 3Rd edition, Elsevier Mosby, St. Louis, MO 2005, p. 403

13.1.11 Human Toxicity Excerpts

/HUMAN EXPOSURE STUDIES/ Bronchoalveolar lavage (BAL) cell and cytokine concentrations, pulmonary function, and peripheral blood neutrophil concentrations /were quantified/ in 6 healthy volunteers 18-20 hr after inhalation of fine and ultrafine magnesium oxide particles produced from a furnace system model. ...Postexposure studies /were compared/ with control studies from the same 6 subjects. Mean +/- standard deviation (SD) cumulative magnesium dose was 4,138 +/- 2,163 min x mg/cu m. By weight, 28% of fume particles were ultrafine (<0.1 micron in diameter) and over 98% of fume particles were fine (<2.5 micron in diameter). There were no significant differences in BAL inflammatory cell concentrations, BAL interleukin (IL)-1, IL-6, IL-8, tumor necrosis factor, pulmonary function, or peripheral blood neutrophil concentrations postexposure compared with control. ... /These/ findings suggest that high-dose fine and ultrafine magnesium oxide particle exposure does not produce a measurable pulmonary inflammatory response. These findings are in marked contrast with the well-described pulmonary inflammatory response following zinc oxide particle inhalation. ... /It was concluded/ that fine and ultrafine particle inhalation does not result in toxicity in a generic manner independent of particle composition.
Kuschner WG, et al; Environ Health Perspect 105 (11): 1234-1237 (1997)
/HUMAN EXPOSURE STUDIES/ Ambient air particulates derived from a magnesite-processing plant contain magnesium oxide (85-90%), iron oxide (7-8%), calcium oxide (about 2.5-3%), Al- and Si oxides (0.1-0.5%) as well as additional elements in trace amounts as follows: Ni, Cr, Mn, Co, Hg, Cd, Pb, V, Ba, Ag, Cu and Sn. Magnesite clinker is manufactured from raw magnesite by baking in rotary furnaces using the Leseps-Polysius system, which represents the source of particulate pollutants entering the atmosphere. In the area heavily polluted by magnesite particles, the health impact using the data obtained from the exposed humans and animals was assessed. The reason for this study were the data on the increased frequency of respiratory diseases in children in the polluted area. In a group of children (9-10 years of age) residing in the area, the immune response to ambient air pollutants exposure in comparison to a non-exposed group living outside the polluted area was investigated. A statistically significant decrease in the amount of salivary lysozyme, SlgA, IgG and albumin in the exposed group was observed. ...
Reichrtova E, Ondrejcakova I; Cent Eur J Public Health 6 (3): 238-240 (1998)
/HUMAN EXPOSURE STUDIES/ Examination of 95 workers exposed to an unspecified concentration of MgO dust revealed slight irritation of the eyes and nose. ... Conjunctivitis, nasal catarrh, and coughing up discolored sputum /was cited/ after industrial exposures, but even when such exposures doubled serum magnesium as compared to normal concentrations, no systematic effects were noted amoung these workers; however, serum calcium concentrations were elevated.
American Conference of Governmental Industrial Hygienists. Documentation of Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices for 2001. Cincinnati, OH. 2001., p. 1
/HUMAN EXPOSURE STUDIES/ ... Four volunteers ...were exposed for 1-9 min to freshly generated /magnesium oxide/ fume at 410, 420, 430, or 580 mg/cu m. Although slight reactions were observed after <10 min of exposure at these concns, it was believed that increased exposures would lead to more severe reactions. Inhalation of magnesium oxide produced a febrile reaction and a leukocytosis, similar to metal fume fever, in the exposed subjects analogous to that caused by inhalation of zinc oxide.
American Conference of Governmental Industrial Hygienists. Documentation of Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices for 2001. Cincinnati, OH. 2001., p. 2
For more Human Toxicity Excerpts (Complete) data for MAGNESIUM OXIDE (10 total), please visit the HSDB record page.

13.1.12 Non-Human Toxicity Excerpts

/LABORATORY ANIMALS: Acute Exposure/ Cats that inhaled the MgO fumes for 3 hr showed obvious dyspnea when removed from the exposure chamber, were decidedly cold to the touch, and were lethargic. These animals rapidly returned to normal and showed no subsequent ill effects upon cessation of MgO inhalation.
American Conference of Governmental Industrial Hygienists. Documentation of Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices for 2001. Cincinnati, OH. 2001., p. 1
/LABORATORY ANIMALS: Acute Exposure/ Magnesium oxide, magnesium hydroxide, magnesium sulfate, magnesium trisilicate, and magnesium citrate were added to a calcium oxalate lithogenic diet in order to determine their effects in preventing lithogenesis. Male Wistar strain rats which had been fed the glycolic acid diet developed marked urinary calculi within 4 wks. Rats in the magnesium hydroxide, magnesium citrate, and magnesium trisilicate groups, however, had almost no stones in the urinary system. Rats in the magnesium oxide and magnesium sulfate groups showed significantly less effect than those in the former three groups. During the experimental period, the 24-hr urinary oxalate excretion and concentration were higher in the glycolic acid group than in the other groups. The urinary citrate excretion and concentration were the highest in the magnesium hydroxide and magnesium citrate groups and higher in the magnesium trisilicate and magnesium oxide groups than in the magnesium sulfate and glycolic acid groups. Similar trends were observed in the urinary magnesium excretion and in its concentration. The urinary calcium excretion and concentration were higher in the experimental groups than in the glycolic acid group. The urinary calcium/magnesium ratio remained mostly unchanged. Therefore, it can be concluded that alkaline magnesium salts increase the urinary calcium and magnesium concentrations, without changing the calcium/magnesium ratio, and inhibit urinary calculi formation, most likely by increasing the urinary citrate concentration.
Ogawa Y, et al; J Urol 144 (2): 385-389 (1990)
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Thirty-six midlactation Holstein cows were used in a randomized incomplete block design to evaluate lactational responses to varying dietary concentrations of Mg supplemented by MgO or Mg chelate. Basal diet was 41:4:55 corn silage:cottonseed hulls:concentrate (0.21% total Mg). Magnesium oxide was added to the basal diet to give 0.32, 0.37, and 0.43% total dietary Mg, and Mg chelate was added to provide 0.23, 0.25, and 0.27% Mg, /dry matter/ (DM) basis. Dietary treatments were formulated to supply equal concentrations of bioavailable Mg from either Mg source. Dry matter intake and milk yield were greater by cows fed MgO-supplemented than Mg chelate-supplemented treatments. Milk fat percentages were not affected. Milk protein percentages increased with Mg chelate compared with protein percentages with MgO. Treatments did not affect gross efficiency (4% /fat corrected milk/ (FCM)/DM intake) or body weight change. Lack of response to Mg chelate suggested that either the bioavailability was not as high as assumed or that sufficient total bioavailable Mg was not provided in those treatments. A companion in vitro experiment showed that MgO-supplemented concentrates, with more total supplemental Mg, supplied two to three times more soluble Mg than Mg chelate-supplemented concentrates.
Lough DS et al; J Dairy Sci. 73 (2): 413-24 (1990)
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ ... Wistar rats were immunized using sheep erythrocyte suspension 4 days after the intratracheal and intravenous administration of /magnesite/ dust suspension. The antibody response was evaluated by counting PFC cells (plaque-forming cells) in the lung and spleen. The antibody response in the spleen increased significantly after intratracheal and intravenous dust administration. The increase in PFC in the lung was on the border of significance ... Total serum complement was evaluated in Wistar rats during the 2 months of chamber exposure to magnesite dust and 25 days after the end of exposure. Total serum complement (CH50) increased in the course of exposure and this increase continued during the 25 days after the end of exposure ... No significant impact was observed in the case of magnesite dust administration on the mean survival time (in days) of /ear/ skin allograft. /In/ in vitro experiments ... on the immune binding to the membrane Fc receptor of rabbit pulmonary alveolar macrophages (PAM) of sheep erythrocytes sensitized with rabbit amboreceptor ... magnesium oxide was found to produce an inhibitory effect similar to that of magnesite dust ... Experiments were carried out on inbred C57 BL mice to assess the effect of 3-month chamber exposure to magnesite dust on nonspecific antitumor immunity to inoculated syngeneic lymphoma. The growth of the tumor in exposed animals was more pronounced than in intact animals.
Reichrtova E, Takac L; J Hyg Epidemiol Microbiol Immunol 36 (4): 235-243 (1992)
For more Non-Human Toxicity Excerpts (Complete) data for MAGNESIUM OXIDE (19 total), please visit the HSDB record page.

13.1.13 Non-Human Toxicity Values

LD50 Rat female oral 3990 mg/kg
DHHS/NTP; Summary of data for chemical selection: Magnesium Oxide (1309-48-4) p. 15 (2001). Available from, as of September 20, 2011: https://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/Magnesiumoxide.pdf
LD50 Rat male oral 3870 mg/kg
DHHS/NTP; Summary of data for chemical selection: Magnesium Oxide (1309-48-4) p. 15 (2001). Available from, as of September 20, 2011: https://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/Magnesiumoxide.pdf
LD50 Mouse oral 810 mg/kg
DHHS/NTP; Summary of data for chemical selection: Magnesium Oxide (1309-48-4) p. 15 (2001). Available from, as of September 20, 2011: https://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/Magnesiumoxide.pdf

13.2 Ecological Information

13.2.1 Ecotoxicity Excerpts

/ACCIDENTAL POISONINGS/ Holstein bull calves were fed 1, 2, and 4% supplemental Mg as magnesium oxide. Diarrhea was most obvious effect of high Mg intake.
Gentry et al; J Dairy Sci 61 (12): 1750-1754 (1978)

13.2.2 Natural Pollution Sources

Magnesium oxide occurs in nature as the mineral periclase(1).
(1) Patnaik P; Handbook of Inorganic Chemicals. New York, NY: McGraw-Hill p. 529 (2003)

13.2.3 Artificial Pollution Sources

The production and use of magnesium compounds as refractories, as chemical intermediates, and in construction materials(1,2) result in their release to the environment through various waste streams(SRC). The production and use of magnesium compounds in environmental applications and in agriculture(1,2) results in their direct release to the environment(SRC). About 69% of the magnesium compounds used in the United States were used for refractories (e.g., olivine)(1). The remaining 31% of magnesium compounds were used in agriculture as fertilizer or animal feed (e.g, magnesium oxide, magnesium sulfate), as chemical intermediates (e.g., magnesium chloride, magnesium hydroxide, magnesium carbonate, magnesium oxide) , construction materials (e.g., magnesium oxide), environmental (e.g., magnesium oxide, magnesium hydroxide), and industrial applications (e.g., magnesium oxide)(1,2). Other uses include road dust and ice control (e.g., magnesium chloride), pulp and paper applications (e.g.,magnesium sulfate), pharmaceuticals (e.g., magnesium sulfate, magnesium carbonate, magnesium oxide), and cosmetics (e.g., magnesium carbonate)(1,2).
(1) Kramer DA; USGS Minerals Yearbook for Magnesium Compounds (2001). Available from https://minerals.usgs.gov/minerals/pubs/commodity/magnesium/401302.pdf as of Oct 21, 2002.
(2) Kramer DA; USGS Mineral Commodity Summary for Magnesium Compounds (2002). Available from https://minerals.usgs.gov/minerals/pubs/commodity/magnesium/401302.pdf as of Oct 21, 2002.

13.2.4 Sediment / Soil Concentrations

SEDIMENT: Sediment from three Antarctic lakes (collected in 1993/94) contained between 3,350 to 5,240 mg/kg dry wt magnesium(1). The mean concentration of magnesium (as MgO) in surficial sediment from Lake Ontario ranged from 2.79 to 2.85% dry weight(2). In Po river (Italy) suspended solids collected in 1989, the concentration of magnesium was 1.8%(3).
(1) Mentesi E et al; Intern J Environ Anal Chem 71: 245-255 (1998)
(2) Mudroch A; Environ Monit Assess 28: 117-129 (1993)
(3) Pettine M et al; Sci Tot Environ 145: 243-265 (1994)

13.2.5 Probable Routes of Human Exposure

According to the 2006 TSCA Inventory Update Reporting data, the number of persons reasonably likely to be exposed in the industrial manufacturing, processing, and use of magnesium oxide is 1000 or greater; the data may be greatly underestimated(1).
(1) US EPA; Inventory Update Reporting (IUR). Non-confidential 2006 IUR Records by Chemical, including Manufacturing, Processing and Use Information. Washington, DC: U.S. Environmental Protection Agency. Available from, as of Sept 8, 2011: https://cfpub.epa.gov/iursearch/index.cfm
NIOSH (NOES Survey 1981-1983) has statistically estimated that 765,812 workers (149,523 of these are female) are potentially exposed to manganese oxide in the US(1).
(1) NIOSH; NOES. National Occupational Exposure Survey conducted from 1981-1983. Estimated numbers of employees potentially exposed to specific agents by 2-digit standard industrial classification (SIC). Available from, as of Nov 2, 2010: https://www.cdc.gov/niosh/ipcs/nicstart.html
Concentration of MgO sufficiently great to cause metal-fume fever have not been encountered in air of melting room, which has been reported to contain between 0.08 & 0.7 mg/cu m...
Patty, F. (ed.). Industrial Hygiene and Toxicology: Volume II: Toxicology. 2nd ed. New York: Interscience Publishers, 1963., p. 1075

14 Associated Disorders and Diseases

Associated Occupational Diseases with Exposure to the Compound
Metal fume fever [Category: Acute Poisoning]

15 Literature

15.1 Consolidated References

15.2 NLM Curated PubMed Citations

15.3 Springer Nature References

15.4 Thieme References

15.5 Chemical Co-Occurrences in Literature

15.6 Chemical-Gene Co-Occurrences in Literature

15.7 Chemical-Disease Co-Occurrences in Literature

16 Patents

16.1 Depositor-Supplied Patent Identifiers

16.2 WIPO PATENTSCOPE

16.3 FDA Orange Book Patents

16.4 Chemical Co-Occurrences in Patents

16.5 Chemical-Disease Co-Occurrences in Patents

16.6 Chemical-Gene Co-Occurrences in Patents

17 Interactions and Pathways

17.1 Chemical-Target Interactions

17.2 Drug-Drug Interactions

17.3 Drug-Food Interactions

  • Take with food. When using magnesium to treat calcium oxalate nephrolithiasis, magnesium oxide should be taken with food.
  • Take with or without food. Many different products contain magnesium oxide; refer to the product monograph for more specific instruction. Taking magnesium supplements with food may reduce the risk of diarrhea.

18 Biological Test Results

18.1 BioAssay Results

19 Classification

19.1 MeSH Tree

19.2 NCI Thesaurus Tree

19.3 KEGG: Drug

19.4 KEGG: ATC

19.5 KEGG: JP15

19.6 KEGG: Risk Category of Japanese OTC Drugs

19.7 KEGG: OTC drugs

19.8 KEGG: Drug Groups

19.9 KEGG: Drug Classes

19.10 ChemIDplus

19.11 UN GHS Classification

19.12 NORMAN Suspect List Exchange Classification

19.13 EPA Substance Registry Services Tree

19.14 MolGenie Organic Chemistry Ontology

20 Information Sources

  1. Athena Minerals
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  7. Hazardous Substances Data Bank (HSDB)
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  9. ILO-WHO International Chemical Safety Cards (ICSCs)
  10. The National Institute for Occupational Safety and Health (NIOSH)
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  11. EU Food Improvement Agents
  12. Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
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  14. Open Targets
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  15. ChEMBL
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  16. ClinicalTrials.gov
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    https://clinicaltrials.gov/ct2/about-site/terms-conditions#Use
  17. Comparative Toxicogenomics Database (CTD)
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  18. Consumer Product Information Database (CPID)
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    https://www.whatsinproducts.com/contents/view/1/6
  19. DailyMed
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  21. Drugs@FDA
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  25. NITE-CMC
    Magnesium oxide - FY2015 (New/original classication)
    https://www.chem-info.nite.go.jp/chem/english/ghs/15-mhlw-0007e.html
  26. FDA Regulatory Status of Color Additives
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  28. KEGG
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    Therapeutic category of drugs in Japan
    http://www.genome.jp/kegg-bin/get_htext?br08301.keg
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    http://www.genome.jp/kegg-bin/get_htext?br08303.keg
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  30. NLM RxNorm Terminology
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    https://www.nlm.nih.gov/research/umls/rxnorm/docs/termsofservice.html
  31. PharmGKB
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  32. SpectraBase
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  34. Thieme Chemistry
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  35. WHO Anatomical Therapeutic Chemical (ATC) Classification
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  39. PubChem
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  42. EPA Substance Registry Services
  43. MolGenie
    MolGenie Organic Chemistry Ontology
    https://github.com/MolGenie/ontology/
  44. PATENTSCOPE (WIPO)
  45. NCBI
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