Cobalt is a metal that occurs naturally in many different forms. Small amounts of it are found in most rocks, soil, water, plants, and animals. Cobalt is a component of vitamin B-12, which is required for good health. The largest use of cobalt metal is to make alloys, which retain strength even when very hot. It is also used to help paint dry quickly. Cobalt is also used to make artificial body parts such as hip and knee joints. Cobalt carbonate is used in ceramics and as an animal feed supplement in trace amounts. Cobalt chloride is used as a humidity and water indicator, in electroplating, in the manufacture of vitamin B-12, as a fertilizer and feed additive in trace amounts. Cobalt oxide is used in pigments for ceramics and glass, in fast drying paints and varnishes, in semiconductors, in enamel coatings on steel, and again as an animal feed additive in trace amounts. Cobalt sulfate is used in electroplating, in batteries, as a drying agent in inks and varnishes, in enamels, and ceramics, and as a feed and fertilizer additive.
Substance name: Cobalt & compounds
CASR number: 7440-48-4
Molecular formula: Co
Synonyms: Cobalt compounds: Cobalt carbonate, cobalt chloride, cobalt oxide, cobalt sulfate, cobalt nitrate
Cobalt metal is an odourless shiny, silvery metal, when first exposed to air.
Melting Point: Cobalt metal: about 1495°C
Boiling Point: Cobalt metal: 2870 to 3100°C
Specific Gravity: 8.92
Pure cobalt does not dissolve in water, but will dissolve (or react) with acids. It will burn when exposed to heat. The fumes may be hazardous. Compounds that are not soluble in water are cobalt carbonate and cobalt oxide. Compounds that are soluble in water are cobalt nitrate and cobalt sulfate.
The National Pollutant Inventory (NPI) holds data for all sources of cobalt and compounds emissions in Australia.
Cobalt has both beneficial and harmful effects on humans. It is part of vitamin B-12, and may be used in the treatment of anaemia. Exposure to cobalt may cause lung effects, which include respiratory irritation, coughing, asthma, pulmonary oedema, and pneumonia. The International Agency for Research on Cancer classifies cobalt as a 'possible human carcinogen'. Exposure to cobalt salts may cause skin problems, and may damage the kidneys and cause lung damage. Cobalt can damage the heart, causing heart failure. Repeated exposures can cause scarring of the lungs (pulmonary fibrosis) which may not be noticed without a chest x-ray. This can be disabling or fatal.
Entering the body
Cobalt and cobalt products will enter the body if we breathe in contaminated air, drink contaminated water, or eat food containing cobalt. Small amounts occur naturally in food, water, and the air (from soil which has become dust). These small amounts are essential for good health.
Everyone is exposed to low levels of cobalt in the air, water and food we eat. Cobalt can also be absorbed through the skin. Workers in the industries that use or produce cobalt and its compounds (coal mining, hard metal industries, cobalt dye painting, and ore processing and chemical manufacturing) are at risk of higher exposure. Consumers can be exposed to cobalt and its compounds by exposure to air from production and processing facilities using cobalt and its compounds.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standards for cobalt and compounds through the workplace exposure standards for airborne contaminants. 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.
- Maximum eight hour time weighted average (TWA): 0.05 mg/m3
- Maximum eight hour time weighted average (TWA): 0.1 mg/m3
- Maximum eight hour time weighted average (TWA): 0.1 mg/m3
Drinking water guidelines
There is no guideline for cobalt and compounds in the Australian Drinking Water Guidelines.
Cobalt and its salts have high acute (short-term) toxicity on aquatic life. It also has high chronic (long-term) toxicity on aquatic life. There is not sufficient data to determine the acute or chronic toxicity of cobalt and its compounds on plants, birds or land animals. Cobalt and its compounds are highly persistent in water and the environment. Cobalt will bioaccumulate or concentrate in the tissues of fish.
Entering the environment
Industrial emissions of cobalt and or cobalt compounds can produce elevated, but still low level concentrations in the atmosphere around the source. Because of its short life expectancy in the atmosphere cobalt and or cobalt compounds is expected to be confined to the local area within which it is emitted.
Where it ends up
Cobalt and its compounds are expected to act like other particles in the atmosphere. The way they deposit in the local area will depend on the local wind and rain. They are expected to remain in the atmosphere from 5 to 15 days.
No national guidelines.
Cobalt is mainly emitted from sources where it is used in the production of steel and other alloys. It may be emitted to air, land or water from these sources. Automotive repair shops may be significant emitters (to air) of cobalt. It will also be emitted to air, land and water during the mining or refining of nickel, copper, silver, lead and iron.
Diffuse sources, and industry sources included in diffuse emissions data
Cobalt may be emitted to air, land or water from the manufacture, use or disposal of paints and varnishes. It may also be emitted to air, land or water from the manufacture, use or disposal of ceramic, inks, and enamels.
Cobalt is found in soil, dust, seawater, volcanic emissions, and smoke from forest and bush fires.
Small amounts of cobalt have been found in motor vehicle exhaust.
Consumer products containing cobalt and its compounds include: vitamin B-12, animal feeds and fertilisers, paints, varnish, enamels and ceramics. It is in metals used at high temperatures (e.g. some car parts).
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