Substance fact sheet
The National Pollutant Inventory (NPI) provides information on the types and amounts of pollutants being emitted in the Australian community.
This page provides facts about mercury. It describes how you might be exposed to this substance, how exposure might effect you and the environment, common uses, comparative data about mercury and its physical and chemical properties.
For more information about some of the terms used in this page, see the NPI glossary.
The National Pollutant Inventory (NPI) holds data for all sources of mercury and compounds emissions in Australia.
The nervous system is very sensitive to all forms of mercury. Exposure to high levels of any types of mercury can permanently damage the brain, kidneys, and developing foetus. Effects on brain functions may result in irritability, shyness, tremors, changes in vision or hearing and memory problems. High exposures of mercury vapour may cause chest pain, shortness of breath, and a build up of fluids in the lungs (pulmonary oedema) that can be fatal. Methyl mercury and mercury metal vapours are especially harmful, because more mercury reaches the brain. Long term exposures may cloud the eye. Contact with mercuric chloride can cause burns to the skin and permanent damage to the eyes. Mercury also accumulates in the body.
Mercury and mercury containing products will enter the body if we breathe in contaminated air, drink contaminated water, eat contaminated food, or have our skin come into contact with it. Mercury may be absorbed through the skin. Mercury released into the environment is converted into methyl mercury by bacteria. The methyl mercury will then build up in the tissues of fish and shellfish. Humans (and other animals) may also be poisoned by eating these fish or shellfish.
Mercury can be absorbed through the skin. Workers in the industries that use or produce mercury and its compounds (mercury mines and refineries, chemical manufacturing, dental/health fields, metal smelters) are at risk of exposure. Workers in fossil fuel power plants and in cement manufacturing may be exposed to mercury compounds if they are exposed to gaseous process emissions. Consumers can be exposed to mercury and its compounds by exposure to air from production and processing facilities using mercury and its compounds, by eating fish or shellfish contaminated with methyl mercury. People can also be exposed to mercury from dental work and medical treatments.
Worksafe Australia:
The eight-hour time weighted average (TWA) exposure limit is 0.05 mg/m3. Mercury bichloride is also considered to be toxic by inhalation, skin contact, or swallowing.
Australian Drinking Water Guidelines (NHMRC and ARMCANZ, 1996):
Maximum of 0.001 mg/L (i.e. 0.000001 g/L)
See current guidelines for any recent changes.
Both mercury and its compounds have high acute (short-term) and have high chronic (long-term) toxicity on aquatic life. Eating fish contaminated with mercury has caused poisoning in humans; birds and land animals exposed in the same manner could also be subject to the same effects. There is not sufficient data to determine the acute toxicity of mercury and its compounds on plants, birds or land animals. Mercury and its compounds are highly persistent in water and the environment and will bioaccumulate or concentrate in the tissues of fish. These concentrations will be considerably higher than the water from which the fish is taken.
Mercury chloride will act as a particle, following wind patterns, and being deposited by rain. Elemental mercury may be a gas in the atmosphere. Emissions of mercury and or mercury compounds can produce elevated, but still low-level concentrations in the atmosphere around the source. Elemental mercury can evaporate from both soil and water into the atmosphere.
When mercury enters the environment from emissions in the air, water or soil, it oxidises into other compounds of mercury. These other forms of mercury form methyl mercury, through either chemical or biological (bacteria) processes. Methyl mercury builds up in the tissues of fish and shellfish. In areas of mercury contamination, larger and older fish tend to have higher levels of mercury. Mercury emitted to the environment will remain for years.
Australian Water Quality Guidelines for Fresh and Marine Waters: (ANZECC, 1992):
Maximum of 0.0001 mg/L (i.e. 0.0000001 g/L)
See current guidelines for any recent changes.
Mercury is used in its pure form in thermometers and barometers. Many batteries contain mercury. It is used in floodlights, streetlights, and other outdoor or powerful lights. It is also used as a catalyst in the chemical manufacturing industry. It is used to conduct electricity (i.e. thermostats). Mercury is used in dental amalgams. It is also used in the mining industry to extract gold and silver ores. Mercuric chloride is used in the manufacture of disinfectants, other chemicals, and as a catalyst. Mercuric chloride is used in photography and embalming. Bacteria in the water and the soil primarily produce methyl mercury.
Fossil fuel power plants emit to air, precious metal mining operations may emit to water or land, metal smelters may emit to air, cement manufacture may emit to air. Municipal landfills, sewage, metal refining, and chemical manufacturing are also significant potential emitters of mercury to land and water.
Burning of fossil fuels (home heating oil, petrol) emits to air, disposal of batteries, thermometers and other mercury containing products may emit to land, and photographic processing facilities may emit mercury to water.
The combustion of petrol releases small amounts of mercury to air.
Batteries, thermometers, barometers, thermostats, and mercury lights are some of the consumer products that contain mercury. Photographic toners contain mercuric chloride.
Mercury is a naturally occurring element that is found in rocks and ores. Mercury is released into the atmosphere by evaporating from soils, from volcanic activity, and from burning of fossil fuels (coal, oil, petrol, asphalt, etc.).
Approximately 400 substances were considered for inclusion on the NPI reporting list. A ranking total and hazard score were given based on health and environmental hazards and human and environmental exposure to the substance.
Mercury and compounds was ranked as 35 out of 400. The total hazard score taking into account both human health and environmental criteria is 3.7.
On a health hazard rating of 0 - 3 mercury and compounds registers 1.7. A score of 3 represents a very high hazard to health, 2 represents a medium hazard and 1 is harmful to health.
On an environmental rating of 0 - 3 mercury and compounds registers 2. A score of 3 represents a very high hazard to the environment and 0 a negligible hazard.
Factors taken into account to obtain this ranking and these scores 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. 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.
| Substance name | Mercury & compounds |
| CASR number | 7439-97-6 |
| Molecular formula | Mercury (Hg): 7439-97-6; Mercury bichloride (HgCl2): 7487-94-7; Methyl Mercury (CH3Hg+): 22967-92-6 |
| Synonyms | Mercury: Quick Silver, Liquid silver, hydragyrum. Mercury bichloride: Mercuric bichloride, mercuric chloride, Bichloride of Mercury, Corrosive Sublimate, Mercury perchloride, Mercury (II) Chloride, Mercury chloride, perchloride of mercury, sublimate |
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Physical properties: Mercury: Mercuric chloride: Chemical properties: |
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There is more information that may be useful in understanding some of the issues surrounding the NPI.