Asbestos

For more information on asbestos, inlcuding the current ASCC Codes of Practice, please visit the Asbestos page in the Hazardous Substances and Dangerous Goods section of the ASCC website (www.ascc.gov.au)

Chrysotile

TWA- 0.1 f/ mL

A revised exposure standard was declared by NOHSC in July 2003 .

No standard should be applied without reference to Guidance on the interpretation of Workplace exposure standards for airborne contaminants.

Chrysotile was the subject of a Priority Existing Chemical ( PEC ) assessment by the National Industrial Chemicals Notification and Assessment Scheme ( NICNAS ) in 1999 . The PEC assessment forms the main scientific documentation that supports the amendment to the NES .

Amosite

TWA- 0.1 f/ mL

Crocidolite

TWA- 0.1 f/ mL

Other forms

TWA- 0.1 f/ mL

Any mixture of these, or where the composition is unknown

TWA- 0.1 f/ mL

Historical information about the asbestos exposure standards is provided below. This information has been reproduced from Documentation of the Exposure Standards [NOHSC:10003(1997)].

NOTE THAT THE CURRENT EXPOSURE STANDARDS FOR ASBESTOS ARE SHOWN ABOVE.

1. GENERAL HEALTH ASPECTS

Since early this century, the health effects arising from inhalation of asbestos fibres have begun to be recognised . Small fibrous particles may become airborne and be inhaled . Fibres below 3 microns in diameter are referred to as "respirable", meaning that they may enter the deepest parts of the lung.

Inhalation of high concentrations of asbestos may result in asbestosis, a progressive scarring of lung tissue . Further development of scar tissue (fibrosis) may occur after the cessation of exposure . Mesothelioma and lung cancer are also associated with the inhalation of asbestos fibres . Generally, fibres below 3 microns in diameter and greater than 8 microns in length are potentially carcinogenic, and the risk of cancer increases as fibre diameter decreases . The risk of cancer is also greater with increased exposure to asbestos, and vice versa.

All forms of asbestos have been found to cause lung cancer, both in a variety of experimental animals and in exposed humans . Cigarette smoking greatly increases the risk of lung cancer in people heavily exposed to asbestos . Recent evidence suggested that the lung cancer risk associated with the manufacture of chrysotile textile would be greater than that of other chrysotile applications (3).

There is a long latency period which ranges from 10 to 50 years between exposure and the development of mesothelioma . The majority of mesothelioma cases appear to be related mainly to crocidolite . The tumours have also been observed in occupational groups exposed to arnosite . However, there is evidence that peritoneal mesothelioma never, and pleural mesothelioma rarely, has occurred in humans in relation to exposure to chrysotile alone (3).

In 1977, the International Agency for Research on Cancer ( IARC ) published a review on asbestos (4) . This IARC report, having considered experiments with animals as well as epidemiological evidence, concluded that "it is not possible to assess whether there is a level of exposure in humans below which an increased risk of cancer would not occur".

2. DEVELOPMENT OF EXPOSURE STANDARDS FOR ASBESTOS IN AUSTRALIA

Before the establishment of the National Occupational Health and Safety Commission in 1985, the National Health and Medical Research Council ( NHMRC ) had played an active role in dealing with the occupational health aspects of asbestos in Australia . In 1978, NHMRC approved the establishment of an Asbestos ad hoc Subcommittee to address the occupational and public health issues of asbestos . Upon the recommendations of this Subcommittee, NHMRC adopted the following exposure standards for asbestos at the 91st Session of the Council in June 1981 (5) :

NHMRC also recommended that the importation and mining of raw crocidolite fibre and the use of crocidolite in new work be prohibited in Australia .

In October 1983, NHMRC reviewed the carcinogenicity of amosite and recommended (4) that from 1 July 1984, the exposure standard for amosite be reduced to 0.1 fibre/ mL , and raw amosite fibre, like crocidolite, should be determined a prohibitive substance under the provisions of the Customs (Prohibited Import) Regulation No.90, 1956 . The exposure standards for crocidolite and chrysotile remained unchanged.

With the establishment of the National Commission in 1985, the responsibility for the development of occupational health standards was transferred from the NHMRC to the tripartite Commission . A Working Party on Asbestos was established under the auspices of the National Commission's Standards Development Standing Committee, which finally produced the Asbestos Guide (1) and Code of Practice (6) . In the Asbestos Guide, the 1984 NHMRC exposure standards for asbestos were again recommended . Moreover, to complement the role of this Asbestos Working Party, an additional Working Party was also formed to review the NHMRC Membrane Filter Method for Estimating Airborne Asbestos Dust . This latter Working Party has developed the Guidance Note on the Membrane Filter Method for Estimating Airborne Asbestos Dust (2) .

The three asbestos documents (1,2,6) , in their draft forms, were released for public comment in April 1987 . Following a three month period of public comment, all submissions were examined by either the Asbestos or Membrane Filter Method Working Parties, and the draft document amended as appropriate as a result of this review.

The three final documents (1 ,2,6 ) , with the recommended exposure standards for asbestos, were finally endorsed by the National Commission in May 1988.

REFERENCES

1. National Occupational Health and Safety Commission, Guide to the Control of Asbestos Hazards in Buildings and Structures, NOHSC , Australian Government Publishing Service, Canberra , 1988

2. National Occupational Health and Safety Commission, Guidance Note on the Membrane Filter Method for Estimating Airborne Asbestos Dust, NOHSC , Australian Government Publishing Service, Canberra, 1988

3. Archeson ED & Gardner MJ , Asbestos - the Control Limit for Asbestos, Health and Safety Commission, HMSO, London , 1983

4. International Agency for Research on Cancer, Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Humans, Volume 14, Lyon , 1977

5. National Health and Medical Research Council ( NHMRC ), Report on the Health Hazards of Asbestos, Commonwealth Dept of Health, Australian Government Publishing Service, Canberra , 1982

6. National Occupational Health and Safety Commission, Code of Practice for the Safe Removal of Asbestos, NOHSC , Australian Government Publishing Service, Canberra , 1988

FURTHER READING

1. Becklake MR, 'State of the art: asbestos related disease of the lung and other organs: their epidemiology and implications for clinical practice', American Review of Respiratory Diseases, 114, 187-227, 1976

2. British Occupational Hygiene Society, Committee on Hygiene Standards,'Hygiene standards for chrysotile asbestos dust', Ann Occup Hyg 11, 47, 1968

3. Crump KS & Farrat DB, "Statistical analysis of data on airborne asbestos levels collected in an EPA survey of public buildings", Regulatory Toxicology & Pharmacology, 10, 51-62, 1989

4. Editorial, Lancet, 1238-40, 1978

5. Editorial, Thorax, 35, 561-3, 1980

6. Health and Safety Commission, Asbestos, Final Report of the Advisory Committee, Vol I & II, Her Majesty's Stationery Office, London , 1979

7. International Labour Organisation ( ILO ), Report of a Meeting of Experts on the Safe Use of Asbestos, ILO Doc. MEA/1973/10, ILO , Geneva , 1973

8. McDonald JC et al, 'Dust exposure and mortality in chrysotile mining 1910-75', Br J Ind Med, 37, 11-24, 1980

9. Murray R, "Asbestos: a chronology of its origins and health effects", Br J Ind Med, 47, 361-365, 1990

10. National Institute for Occupational Safety and Health, Estimates of the Fraction of Cancer in the United States Related to Occupational Factors, National Cancer Institute, National Institute of Environmental Health Sciences, 1978

11. Peto J, 'Hygiene standard for chrysotile asbestos', Lancet, 484-9, 1978

12. Royal Commission on Matters of Health and Safety Arising from the Use of Asbestos in Ontario, 3 Volumes, Ont. Ministry of the Attorney General, Toronto, Ont., Canada, 1984

13. Selikoff IJ & Hammond EC (ed.), "Health hazards of asbestos exposure", Annals of New York Academy of Sciences, Vol 330, 1979

14. Selikoff I & Lee D, Asbestos and Disease, p.68-9, Academic Press, London , 1978

15. Wagner JC et al, 'Carcinogenesis and mineral fibres', Brit Med Bull, 36, 53-56, 1978

16. Wagner JC , 'Diseases associated with exposure to asbestos dust', The Practitioner, 223, 28-33, 1979

17. Whitwell F, "Problem in the pathology of disease caused by asbestos", J Royal Society of Medicine, 71, 919-22, 1978

18. Yazicioglu S et al, 'Pleural calcification, pleural mesotheliomas and bronchial cancers caused by tremolite dust' . Thorax, 35, 564-9, 1980

19. Zielhuis RL , Public Health Risks of Exposure to Asbestos, Report of a working group of experts prepared for the Commission of the European Communities Directorate-General for Social Affairs, Health and Safety Directorate, Published by Pergamon Press for the Commission of the European Communities, 1977

Documentation notice:

Entries carrying a notice for National Occupational Health and Safety Commission documentation indicate that these substances have been reviewed in detail by the Exposure Standards Expert Working Group and that documentation supporting the adopted national values is available in the National Commission's Documentation of the Exposure Standards [NOHSC:10003(1997)].