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Substance fact sheet

 

Cadmium and compounds fact sheet

Toyota electrocoat rinse and wash. Photo credit: John Baker

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 cadmium and compounds. It describes how you might be exposed to this substance, how exposure might effect you and the environment, common uses, comparative data about cadmium and compounds 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 cadmium and compounds emissions in Australia .

Health effects

What effect might cadmium and compounds have on my health?

Cadmium, especially cadmium oxide is a 'probable carcinogen'. There is evidence of it causing prostate and kidney cancer in humans, it has been shown to cause lung and testicle cancer in animals. It is also a teratogen, and may cause reproductive damage. Inhalation of smoke from burning cadmium or from cadmium oxide is toxic to the respiratory system. It is unlikely that this sort of exposure would occur except in cases of unusual industrial accidents. Repeated low exposures can cause permanent kidney damage that may go unnoticed. Lung scarring can occur from a single high exposure or repeated low exposures. Long-term exposures can cause anaemia, fatigue and loss of the sense of smell. High exposures can cause rapid lung damage, shortness of breath, chest pain, and a build up of fluid in the lungs. In severe cases death or permanent lung damage occurs. High exposure may also cause nausea, vomiting, cramps, and diarrhoea High exposures are unlikely to occur except in cases of unusual industrial accidents.

How might cadmium and compounds enter my body?

Cadmium and or cadmium compounds will enter the body if we breathe in contaminated air, eat contaminated foods, or drink contaminated water.

How might I be exposed to cadmium and compounds?

Workers in the industries that use or produce cadmium and or cadmium compounds are at risk of exposure. Consumers can be exposed to cadmium and or cadmium compounds by exposure to air from production and processing facilities using cadmium and or cadmium compounds. The most significant route of exposure to cadmium and or cadmium compounds for most members of the general public is through food, since food materials tend to take up and retain cadmium. Plants take up cadmium from the soil, fish and shellfish take up cadmium from the water, etc. Smoking is also an important source of cadmium. Tobacco, like other plants takes up cadmium, which is then inhaled in the smoke.

See Sources for more information.

What are the cadmium and compounds health guidelines?

Worksafe Australia Eight hour time weighted average (TWA) exposure limit: 0.01mg/m³. Worksafe Australia has determined that cadmium and its compounds is a 'probable carcinogen'.

Australian Drinking Water Guidelines (NHMRC and ARMCANZ, 1996):Maximum of 0.002 mg/L (i.e. 0.000002 g/L)

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.

Environmental effects

What effect might cadmium and compounds have on the environment?

In fresh water, cadmium toxicity is influenced by the hardness of the water, the softer the water the greater the toxicity. It has high short and long-term toxicity to aquatic life. No data are available on the short-term effects, or long term effects of cadmium on plants, birds, or land animals, excepting test animals, which did develop lung and testicle cancers. The same scarring of the lungs as found in humans will be present in very high doses in other mammals. Cadmium is highly persistent in the environment and will concentrate or bioaccumulate in aquatic animals.

How might cadmium and compounds enter the environment?

Industrial emissions of cadmium and or cadmium compounds can produce elevated, but still low-level concentrations in the atmosphere around the source. Motor vehicles may also produce elevated levels of cadmium in areas of higher traffic. Tobacco smoke is the primary source of cadmium indoors. Because of their short life expectancy in the atmosphere cadmium and its compounds are usually confined to the local area within which it is emitted.

Where in the environment do cadmium and compounds end up?

Cadmium acts like other particles when in the atmosphere and will be subject to deposition caused by rain or wind. The expected lifetime for particles in the atmosphere will be about 5 to 15 days. Some cadmium compounds are able to leach through soils into ground water. When cadmium compounds do bind to the sediments in water (rivers, lakes, bore water) they are less likely to be bioavailable.

What are the cadmium and compounds environmental guidelines?

Australian Water Quality Guidelines for Fresh and Marine Waters: (ANZECC, 1992):
Fresh water:
Maximum of 0.0002 to 0.002 mg/L (i.e. 0.0000002 to 0.000002 g/L)
Marine water:
Maximum of 0.002 mg/L (i.e. 0.000002 g/L)

Note that the emissions data in the NPI database is not directly comparable with these guidelines.

Common uses

Cadmium compounds are used in the metal plating and battery industry, and as stabilizing agents in many polyvinyl chloride (PVC) products. Cadmium metal is alloyed with copper in the production of automobile radiators. Cadmium chloride is used in the dyeing and printing of fabrics, in electronics component manufacture and in photography. Cadmium oxide is used in electroplating, in semiconductors, and in glass and ceramic glazes. Cadmium sulfide is used in the electronics industry for photocells and light emitting diodes. It is also used as a curing agent in tires. Cadmium is a component of petrol, diesel fuel and lubricating oils.

Sources of emissions

Industry sources

Cadmium is obtained as a by-product from the treatment of zinc, copper, lead, and iron ores, therefore facilities that treat these ores may emit cadmium compounds to the environment (mainly water). Coal and oil burning power plants may emit cadmium compounds to air.

Diffuse sources, and industry sources included in diffuse emissions data

Small industrial domestic use of cadmium products will emit low levels of cadmium to the environment. Tobacco smoke will be an indoor source of cadmium.

Natural sources

Cadmium is a naturally occurring element in the crust of the earth. Coal and other fossil fuels contain cadmium and their combustion releases the element into the atmosphere. Cadmium is found naturally in various ores: lead and copper containing zinc, some iron ores, and in sulfide ore. These can result in emissions to water. Volcanic emissions contain cadmium-enriched particles.

Transport sources

The combustion of motor fuels (petrol) in cars, trucks, and planes result in emissions to air, and particles from tire wear may result in emissions to air, land and water.

Consumer products that may contain cadmium and compounds

Cadmium is found in many domestic products, e.g. tobacco products, phosphate fertilisers, polyvinyl chloride (PVC) products, photocells, petrol, oils, tyres, automobile radiators, some textile dyes and colours, electronic components, heating elements in electric kettles and hot water systems, batteries, and ceramic glazes.

Comparison to other substances

NPI rank

Approximately 400 substances were considered for inclusion on the NPI reporting list. A ranking and total hazard score was given based on health and environmental hazards and human and environmental exposure to the substance.

Cadmium and compounds was ranked as 6 out of 400. The total hazard score taking into account both human health and environmental criteria is 4.3.

On a health hazard rating of 0 - 3 cadmium and compounds registers 2.3. 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 cadmium and compounds registers 2.0. 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 account 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.

Total hazard rating

Physical and chemical properties

Substance name Cadmium and compounds
CASR number 7440-43-9
Molecular formula Cd; Cadmium Chloride: CdCl2 Cadmium oxide: CdO; Cadmium sulfide: CdS
Synonyms

Colloidal cadmium
Cadmium sulfide: greenockite, hawleyite
Cadmium oxide: monteponite

Physical properties:
Pure cadmium, the metal, is a soft silver white colour. Cadmium is most often found combined with other elements, which produces compounds such as Cadmium chloride, Cadmium oxide, and Cadmium sulfite.

Melting Point (°C): Cadmium: 320.9; Cadmium chloride 568; Cadmium oxide 900 (decomposes)
Boiling Point (°C:): Cadmium: 765; Cadmium chloride 967; Cadmium oxide 1385
Vapour Density: Cadmium: 3.9; Cadmium chloride: 6.3; Cadmium oxide: Does not apply

Chemical properties:
Cadmium and its compounds are stable. In water some of the compounds will be quite soluble (cadmium chloride) and others will be insoluble (cadmium oxide). As fine powder cadmium metal will burn, releasing toxic fumes of cadmium oxide.

Sources of information used in preparing this fact sheet

There is more information that may be useful in understanding some of the issues surrounding the NPI.

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