Substance fact sheet
The background information page contains information and concepts that will be useful in understanding some of the issues surrounding the NPI. It is strongly recommended that you read this before reading the information presented below.
For an explanation of some of the terms used in this page, see the Glossary
| Substance name | Magnesium oxide fume |
| CASR number | 1309-48-4 |
| Molecular formula | MgO |
| Synonyms | Synonyms for magnesium oxide fume include airborne magnesium oxide and magnesia fume. |
Physical and chemical properties Physical properties: Magnesium oxide fume is an odourless white opaque smoke. Solid magnesium oxide is a hygroscopic fine white powder. Evaporation at room temperature is negligible. It has the following physical properties. Melting Point (°C): 2852 Boiling Point (°C): 3600 Specific Gravity: 3.58 Vapour Density: - Chemical properties: |
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Common uses Magnesium oxide fume does not have any common use. Magnesium oxide is used as a component of refractory crucibles, fire bricks, insulation, rubber compounds, magnesia cements and boiler scale compounds. It is also used as a reflector in optical instruments and as a white colour standard. |
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Sources of emissions Point sources In any industrial workplace where magnesium and magnesium compounds and alloys are used in "hot" operations such as welding, brazing, soldering, plating, cutting and metallising, magnesium oxide fumes may be formed due to the high temperatures reached in these operations. Examples include welding operations with magnesia in fluxes or the combustion of magnesium metal. Diffuse sources, and point sources included in aggregated emissions data Sub-threshold facilities. Natural sources There are no natural sources for magnesium oxide fume. Mobile sources There are no mobile sources for magnesium oxide fume. Consumer products which may contain Magnesium oxide fume There are no consumer products that produce magnesium oxide fume under normal conditions. |
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Health effects How might I be exposed to Magnesium oxide fume? Inhalation of magnesium oxide can occur in industrial workplaces. Exposure can usually be minimised by adequate ventilation at the site of formation. A respirator may be required in some situations. By what pathways might Magnesium oxide fume enter my body? Magnesium oxide fume can be inhaled. Relative health hazard On a health hazard spectrum of 0 - 3 Magnesium oxide fume registers 1.3. A score of 3 represents a very high hazard to health, 2 represents a medium hazard and 1 is harmful to health. Factors that are taken into account to obtain this ranking include the extent of the material's toxic or poisonous nature and/or its lack of toxicity, and the evaluation of its tendency to cause, or not cause cancer and/or birth defects. It does not take into account exposure to the substance. Human exposure is reflected in the NPI rank given to this substance (see comparative data below). A substance that scores highly as a health hazard is arsenic at 2.3 and one of the lowest scores is ammonia at 1.0.  Health guidelines Worksafe Australia defines magnesium oxide as hazardous and has set the exposure standard for magnesium oxide fume to 10 milligram/m3 (TWA). See the Additional Information page for current health information. The Australian NOHSC National Exposure Standards Database link is probably the most useful source of information. Note that the emissions data in the NPI database is not directly comparable with these guidelines. What effect might Magnesium oxide fume have on my health? Breathing freshly generated magnesium oxide fume can irritate the eyes and nose. It can cause metal fume fever triggering symptoms such as headache, cough, sweating, nausea, fever, oppression in the chest and leucocytosis (increase in the number of white blood cells in the blood). The symptoms of metal fume fever might not become manifest until 4-12 hours after exposure and may last for 24 hours. Metal fume fever is not believed to have permanent effects. No chronic (long-term) health effects are known at this time. |
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Environmental effects Environmental Fate Magnesium oxide fume is diluted in air to levels which do not affect the environment. Environmental Transport Magnesium oxide fume can be transported in air. Relative hazard to the environment On an environmental spectrum of 0 - 3 Magnesium oxide fume registers 0.8. A score of 3 represents a very high hazard to the environment and 0 a negligible hazard. Factors that are taken into account to obtain this ranking include the extent of the material's toxic or poisonous nature and/or its lack of toxicity, and the measure of its ability to remain active in the environment and whether it accumulates in living organisms. It does not take into exposure to the substance. Environmental exposure is reflected in the NPI rank for this substance (see comparative data below). A substance that scores highly as an environmental hazard is oxides of nitrogen at 3.0 and one of the lower scores is carbon monoxide at 0.8.  Environmental guidelines See the Additional Information page for current environmental guidelines. No national guidelines. What effect might Magnesium oxide fume have on the environment? There is very little information available on the environmental effects of magnesium oxide fume. If other mammals inhale magnesium oxide fume, they may suffer similar effects as do humans. |
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Comparative data NPI Rank Approximately 400 substances were considered for inclusion on the NPI reporting list. A risk ranking was given based on health and environmental hazard identification and human and environmental exposure to the substance. Some substances were grouped together at the same rank with 208 ranks in total. Magnesium oxide fume was ranked as 47 out of the 208 ranks. Total hazard score (human health + environmental criteria) = 2.1.  |
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Sources of information used in preparing this article
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