Atmosphere

Air toxics and indoor air quality in Australia

State of knowledge report
Environment Australia, 2001
ISBN 0 6425 4739 4

Part C: Factsheets (continued)

Asbestos

Substance name: Asbestos
Fibrous serpentine
Chrysotile (white asbestos)
Fibrous amphiboles
Amosite (brown asbestos)
Crocidolite (blue asbestos)
Tremolite
Anthophyllite
Actinolite
CASR number: Various
Molecular formula: Chrysotile: Mg6Si4O10(OH)8
Amosite: Fe5Mg2(Si8O22)(OH)2
Crocidolite: Na2(Fe3+)2(Fe2+)3Si8O22(OH)2
Tremolite: Ca2Mg5Si8O22(OH)2
Anthophyllite: (Mg,Fe)7Si8O22(OH)2
Actinolite: Ca2(Mg,Fe)5Si8O22(OH)2
Synonyms: Not applicable

Physical and chemical properties

Asbestos is defined as the fibrous form of mineral silicates belonging to the serpentine and amphibole groups of rock-forming minerals. The most common asbestos types are chrysotile (white asbestos), a fibrous serpentine mineral, amosite (brown asbestos) and crocidolite (blue asbestos). Asbestos fibres vary in length and may be straight or curled.

Asbestos fibres are very strong and are resistant to heat and chemicals. Because of these properties, asbestos fibres have been used in a wide range of products. As asbestos fibres are so resistant to chemicals, they are also very stable in the environment, they do not evaporate into air or dissolve in water, and they are not broken down over time.

Common uses

Only chrysotile asbestos is still used in Australia. The main use of raw chrysotile is for the manufacture of friction materials and cement-asbestos fibre sheeting for gasket production for both industrial and automotive applications. A small quantity of raw chrysotile is used in the manufacture of a 'nonsag' additive in epoxy resin adhesives. National Industrial Chemicals Notification and Assessment Scheme (NICNAS) has recommended that chrysotile be phased out. This recommendation is under active consideration by regulatory bodies.

Numerous types of asbestos products were used in the past and still are present (fixed uses) in the general community; they include asbestos-containing sprayed insulation materials in buildings and other structures, lagging, asbestos cement sheets, piping and moulded products in building construction, vinyl asbestos flooring, sealants, textiles (used in heat resistant clothing), conveyor belts, boards (marine and soft building boards), felt (roofing), pipe and electrical coverings and insulating ropes and paper, asbestos yarn for packing, asbestos gloves and headgear.

Sources of emissions

Point sources

The largest point source of chrysotile is during the manufacture of friction materials and compressed asbestos fibre sheeting and the use of chrysotile products. Emissions may also occur during building demolition or other work that disturbs asbestos in situ. These releases are primarily to the air.

Diffuse sources, and point sources included in aggregated emissions data

Not applicable.

Natural sources

Asbestos fibres occur naturally in soil and rocks in some areas. Asbestos is no longer mined in Australia; it is only imported. Chrysotile is the only form of asbestos imported into Australia.

Mobile sources

Chrysotile may be released from brake linings during the braking process.

Consumer products that may contain asbestos

Consumer products containing chrysotile are friction products and gaskets. Other 'one-off' products include blades in high-pressure vacuum pumps, asbestos yarn in packing, asbestos gloves and asbestos washers for miners oil flame safety lamps.

Health effects

How might I be exposed to asbestos?

Inhalation of asbestos fibres is the type of exposure that is most likely to cause adverse health effects for people. Workers in industries that use raw chrysotile or products containing chrysotile (eg manufacture of friction material and gaskets and end-use of these products) may inhale fibres suspended in air. Family members may also be exposed to chrysotile fibres when workers carry chrysotile fibres home on their clothes. People who live or work near chrysotile-related operations may inhale chrysotile fibres that enter the environment. Chrysotile fibres may also be swallowed if eating in areas where chrysotile fibres are in air or if people drink water contaminated with fibres. Buildings insulated with material containing asbestos may also be a source of exposure, if the asbestos is disturbed.

The amount of asbestos a person is exposed to varies according to how many fibres are in the air and how long a person inhales the air containing the fibres.

By what pathways might asbestos enter my body?

Asbestos fibres may enter the body through inhalation and ingestion.

Health guidelines

The current national exposure standard for chrysotile (1 f/mL TWA) has not been uniformly adopted by States and Territories. Current Australian State and Territory exposure standards for chrysotile are:

Exposure standards for other forms of asbestos are uniform in all jurisdictions and are as follows:

Asbestos (all forms) is an established human carcinogen.

What effect might asbestos have on my health?

Health problems are usually related to the amount and length of time of exposure to asbestos. After inhalation, asbestos fibres can enter and become trapped in the airways and lung tissue; the body has difficulty removing the fibres. Continuous exposure to asbestos increases the amount of asbestos that remains in the lungs. Diseases related to asbestos may not show up until several or many years later.

Illnesses associated with asbestos exposure include asbestosis, lung cancer and mesothelioma.

Environmental effects

Environmental fate

Most chrysotile from manufacturing (ie from dust extracted and caught in fabric filters, or offcuts from end-products) should be disposed of to landfill, where it should be contained in plastic bags and secured.

Waste from use (ie used linings and gaskets) is disposed of to unsecured landfill, and would not be readily available for transport by wind or water as it would be encapsulated in end articles, possibly bagged and covered with fill material.

Normal use of motorised vehicles is associated with wear of the brake and clutch linings, which liberates a small amount of chrysotile to the terrestrial environment.

Chrysotile from end-use will reach aquatic systems. Because fibres are small, they could be transported to nearby water bodies through wind or runoff to stormwater drains. Chrysotile is not expected to degrade in aquatic systems although some degradation may occur under acidic conditions.

Disposal of other forms of asbestos such as that removed from buildings is covered by State/Territory regulations listed below:

Environmental transport

Asbestos fibres are very small, so they can be quite mobile in air. Water turbulence may suspend and transport fibres over long distances in surface waters.

Environmental guidelines

There are no national guidelines.

What effect might asbestos have on the environment?

Asbestos can enter the air and water from the weathering of natural deposits and the wearing down of manufactured asbestos products (eg brake pads). Small fibres may remain suspended in air for a long time before settling. Large fibres tend to settle more quickly. Asbestos fibres cannot move through soil and they are not broken down to other compounds in the environment. Therefore, they can remain in the environment for a long time.

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