Arsenic occurs naturally in the environment, and is generally combined with oxygen, chlorine and sulphur to form inorganic arsenic compounds. Organic arsenic compounds are formed when the element combines with carbon and hydrogen.
Arsenic and compounds are used in wood preservatives and pesticides. Arsenic compounds are used for hardening copper, lead and other alloys, most arsenic compounds are manufactured using arsenic trioxide as a raw material and are also used for treating sulphide ores, pesticides and plant and veterinary chemicals.
Substance name: Arsenic
CASR number: 7440-38-2
Molecular formula: As
Synonyms: Grey arsenic, metallic arsenic
Pure arsenic is a silver-grey coloured metalloid (it has metallic as well as non-metallic properties). It can be heated to burn in air, giving off an odour of garlic and white fumes of arsenic trioxide.
Melting Point: 818°C (at 36 atmospheres)
Boiling Point: sublimes at 613°C
Arsenic is odourless and is usually combined with one or more other elements such as oxygen, chlorine and sulphur. Pure arsenic is not soluble in water or organic solvents, but can be dissolved by strong acids. Arsenic trioxide is sparingly soluble in water.
The National Pollutant Inventory (NPI) holds data for all sources of arsenic and compounds emissions in Australia.
Very high levels of arsenic can result in death. Consumption of lower levels of arsenic can cause digestive tract pain, nausea, vomiting and other stomach disorders, decreased production of red and white blood cells, damage to blood vessels, abnormal heart rhythms, a 'pins and needles' feeling in the hands and feet and liver and kidney damage.
Ingesting or inhaling low levels of inorganic arsenic for a long time can cause a darkening of the skin and the appearance of small 'corns' or 'warts' on the hands, feet and torso. Contact with inorganic arsenic may also cause redness and swelling to the skin.
Studies show that ingestion of inorganic arsenic can increase the risk of skin, lung, bladder, liver, kidney or prostate cancer. Inhalation of inorganic arsenic can increase the risk of lung cancer. Inorganic arsenic is a recognised human carcinogen, a substance capable of causing cancer.
Some studies have indicated that long-term exposure to low levels of arsenic in children may result in lower IQ scores. Children may be less efficient at converting inorganic arsenic to the less toxic organic arsenic. For this reason, children may be more susceptible to health effects than adults.
Some evidence exists that inhaled or ingested arsenic can affect pregnant women and their unborn babies. Large doses that cause illness to the pregnant females can also cause low birth weight, foetal malformations or foetal death. Arsenic can cross the placenta and may be found in foetal tissues. Arsenic has also been found at low levels in breast milk.
Entering the body
Arsenic and compounds can enter the body by inhalation or ingestion.
Exposure to arsenic can occur by drinking water or eating foods containing trace amounts of arsenic, by breathing sawdust or smoke from wood treated with arsenic (e.g. CCA (copper chrome arsenate) treated timbers), living in areas with unusually high levels of arsenic in the rock or soil or from working in a job that involves arsenic production or use (such as copper or lead smelting, wood treatment or pesticide application).
Arsenic can be used as a timber preservative or as an insecticide to prevent termites.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standard for arsenic through the workplace exposure standards for airborne contaminants:
- Maximum eight hour time weighted average (TWA): 0.05 mg/m3
These standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
Drinking water guidelines
The Australian Drinking Water Guidelines include the following guidelines for acceptable water quality:
- Maximum of 0.01 milligrams per litre of water for health purposes
Arsenic has a high acute (short-term) toxicity to aquatic life, birds and land animals. Where soil arsenic content is high, plant growth and crop yields may be reduced. Arsenic has a high chronic (long-term) toxicity to aquatic life, and moderate chronic toxicity to birds and land animals.
Organic arsenic compounds are very persistent in the environment and are expected to bioaccumulate in fish and shellfish.
Entering the environment
Arsenic compounds will be in the atmosphere as gases or small particles. They will settle in the soil or water. Arsenic itself is not soluble in water, but many compounds are water soluble and can contaminate ground water. Arsenic can change forms. Fish and shellfish build up organic arsenic compounds. These are not as toxic as the inorganic compounds.
Where it ends up
Arsenic and most of its compounds do not evaporate. They exist as small particles in the atmosphere, and burnt arsenic compounds exist as a gas.
In 2000, the National Water Quality Management Strategy established a water quality guideline for arsenic fresh and marine waters. This level is up to a maximum of 50 micrograms of arsenic per litre of water.
Mining and metal manufacturing are the largest sources of arsenic in Australia. Electricity supply, water supply, sewerage and draining surfaces, can also emit arsenic. Manufacturing industries where arsenic may be used include: food, paper and paper products, glass and glass products, petroleum and coal products and chemicals.
Diffuse sources, and industry sources included in diffuse emissions data
Paved and unpaved roads, windblown dust, burning fuels or wildfires, motor vehicles, solid, liquid and gas fuel combustion, lawn mowing, boating (recreational and commercial), railways, barbeques and backyard incineration activities are all capable of causing arsenic emissions.
Arsenic and compounds occurs naturally in the earth's crust in ores and minerals. These are generally at low concentrations. Arsenic is released into the air by volcanoes and the weathering of arsenic-containing ores.
Arsenic emissions may be present from the vehicle exhaust of cars, aeroplanes, railway operations and from commercial shipping or boating.
Consumer products containing arsenic include timber treatments, wood preservatives, and pesticides.
Sources used in preparing this information
- Agency for Toxic Substances and Disease Registry (ASTDR), ToxFAQs: Arsenic, accessed May 2007.
- Australian and New Zealand Environment and Conservation Council (ANZECC) and Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) (2000), Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Volume 1, The Guidelines, accessed May 2007.
- Australian Pesticides and Veterinary Medicines Authority, PUBCRIS Registered Product Search Engine, accessed May 2007.
- Environment Writer Chemical Backgrounder, accessed May 2007.
- Merck and Co. 2001, Merck Index, 13th Edition, USA.
- National Pollutant Inventory (1999), Contextual Information.
- Office of the Australian Safety and Compensation Council, Exposure Standards: Arsenic and compounds, accessed February 2007.
- Technical Advisory Panel 1999, Final Report to the National Environment Protection Council.
- United Nations, International Chemical Safety Cards: Arsenic and compounds, accessed February 2007.
- Safe Work Australia, Workplace exposure standards for airborne contaminants, accessed June 2021.
- National Health and Medical Research Council (NHMRC), Australian Drinking Water Guidelines (2011) - Updated October 2017, accessed May 2018