State of knowledge report
Environment Australia, 2001
ISBN 0 6425 4739 4
Arsenic and compounds
|Substance name:||Arsenic and compounds|
|Molecular formula:||Arsenic: As
Arsenic trioxide: As4O6
|Synonyms:||For arsenic: Fowler's solution; grey arsenic; colloidal arsenic; metallic arsenic; arsenic black.
For arsenic trioxide: arsenic oxide; arsenic (III) oxide; arsenous trioxide; arsenous acid; arsenous oxide; white arsenic; diarsenic trioxide; crude arsenic; arsenious oxide; arsenic (III) trioxide
Arsenic is a naturally occurring element in the earth's crust. Pure arsenic is a silver-grey coloured metalloid (ie it has metallic as well as nonmetallic properties).
Melting point: 817°C
Boiling point: sublimes at 613°C
Arsenic is odourless and in nature is usually combined with one or more other elements such as oxygen, chlorine, and sulfur. Pure arsenic is not soluble in water or organic solvents, but will be dissolved by strong acids. Arsenic trioxide is moderately soluble in water.
The main use of arsenic is for pesticides, weed killers, and wood preservatives. It is also used for hardening copper, lead and other alloys. Most arsenic compounds are manufactured using arsenic trioxide as a raw material. They are used for wood preservatives, treating sulfide ores, and plant and veterinary chemicals.
Coal-fuelled power plants and copper and lead smelters are the largest point sources of arsenic. These releases are primarily to the air.
Diffuse sources, and point sources included in aggregated emissions data
Pesticides, fungicides, weed killers and wood treatment products release arsenic to the environment. These releases are to the ground, air and water. The burning of treated wood is of particular concern, as the smoke may contain dangerous amounts of arsenic compounds and other chemicals used to treat the wood (such as chromium (VI) and copper compounds).
Arsenic is found in small quantities in nature. It is found in sulfide ores. Arsenic is released into the air by volcanoes and the weathering of arsenic-containing ores and minerals.
There are no known sources of mobile emissions of arsenic or arsenic compounds.
Consumer products that may contain arsenic and compounds
Consumer products containing either arsenic or arsenic products are pesticides, fungicides, weed killers, preserved wood and wood treatment products.
How might I be exposed to arsenic and compounds?
Workers in the industries that use or produce arsenic or arsenic compounds are at risk of exposure. Consumers can be exposed to arsenic or arsenic compounds in air from production and processing facilities such as copper and lead smelters, wood treatment plants, and coal-burning power plants. Consumers may also be exposed to arsenic or arsenic compounds when using consumer products containing arsenic or arsenic compounds, such as pesticides, fungicides, weed killers, preserved wood and wood treatment products. If wood that has been treated is burned in a fireplace or wood-burning stove, it is possible to create acute toxic levels of arsenic products in the air of the home or building.
By what pathways might arsenic and compounds enter my body?
Arsenic or arsenic compounds will enter the body if we breathe in contaminated air from a workplace using or producing arsenic or arsenic compounds. Exposure may come either from ingesting water, soil or air near areas naturally high in arsenic, or from contamination after use for treatment of stock. Consumers may expose themselves to arsenic by breathing sawdust or smoke from wood containing arsenic, or using or misusing pesticides, weed killers, fungicides and wood preservatives.
National Occupational Health and Safety Commission (NOHSC):
- TWA (eight-hour time-weighted average) exposure limit in the workplace for arsenic: 0.05 mg/m³
Australian Drinking Water Guidelines (NHMRC and ARMCANZ 1996):
- Maximum of 0.007 mg/L (ie 0.000007 g/L).
What effect might arsenic and compounds have on my health?
Large doses of arsenic or inorganic arsenic compounds can cause death. They are known poisons. Arsenic acid and its salts are classified by the NOHSC as a Category 1 carcinogen (substance known to be carcinogenic to humans). Some arsenic compounds are also considered to be teratogens (will harm a foetus). Lower levels of exposure to arsenic or its compounds may cause nausea, vomiting, diarrhoea, abnormal heart rhythm, damage to blood vessels, decreased production of blood cells, and a feeling of 'pins and needles' in the hands and feet. Long-term oral exposure (contaminated water) has resulted in stomach disorders, anaemia, a 'pins and needles' feeling in the hands and feet, skin lesions, and liver and kidney damage. The NOHSC classifies both arsenic and arsenic trioxide as toxic if inhaled or swallowed.
Arsenic and most of its compounds are solids that do not evaporate. They exist as small particles in the atmosphere. Burnt arsenic compounds exist as a gas.
These compounds will be in the atmosphere as gases or small particles. They will then settle into the soil or water depending upon where the air currents carry them. Arsenic is not water-soluble, but many of its compounds are water-soluble. These can contaminate groundwater. Arsenic does not break down, but does change form. Fish and shellfish build up organic arsenic compounds, which are not as toxic as the inorganic (noncarbon-based) forms.
Australian Water Quality Guidelines for Fresh and Marine Waters (ANZECC 1992):
- Maximum of 50 µg/L (ie 0.00005 g/L) in fresh or marine waters.
What effect might arsenic and compounds have on the environment?
Arsenic has 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 high chronic (long-term) toxicity to aquatic life, and moderate chronic toxicity to birds and land animals. Arsenic is very persistent in the environment and is expected to bioaccumulate in fish and shellfish, although not in elemental form.
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