The health risk of asbestos fibres
Dr Ben Scalley, Acting Director, Environmental Health Branch, Health Protection NSW
Until the mid-1980s Australia produced asbestos and was one of the world’s highest users of this group of substances . It was not until 2003 that importation, storage, supply, sale, installation, use and reuse were discontinued . Exposure to high levels of asbestos has since been substantially reduced. The potential exposure to asbestos fibres, at generally lower than historical levels, is an issue that continues to cause intense concern among the general public.
Level of exposure
We are all exposed to low levels of asbestos in the air we breathe every day. Background air usually has between 10 and 200 asbestos fibres in every cubic metre of air . This does not result in ill health for most people. The air in buildings and houses with asbestos products may have a similar or an elevated number of asbestos fibres. Levels of 30 to 6,000 fibres per cubic metre have been reported, likely related to factors such as the type of asbestos product used in the building and building maintenance .
The majority of those who develop asbestos related disease have had high levels of exposure over a long duration, such as those who have worked in asbestos mines or tradespeople. In Australia 62.9 per cent of Mesothelioma cases specifically reported previous occupational exposure. The majority of the remainder have had a known exposure to asbestos, such as through home renovation .
There is strong evidence that asbestos fibres at high levels of exposure cause a number of malignancies including lung cancer and mesothelioma . This evidence is based largely on occupational studies where participants were exposed to high levels of asbestos over an extended period of time. An evaluation of the human carcinogenicity dose response relationship by the United States Environment Protection Agency found only studies with an average level of exposure between 31,000,000 and 400,000,000 fibre-years per cubic metre were significantly associated with malignancies . Currently there is little known about what level of risk there is to health from low level or infrequent exposure to asbestos fibres.
Figure 1. Comparison of concentrations of asbestos fibres in air with studies that examine malignancy risk.
Bonded and friable asbestos products
The presence of asbestos fibres, such as in the building material used for a house, is not always of risk to health. Many asbestos products are bonded asbestos cement materials, commonly sheeting used for eaves, fences and roofing. Bonded products do not allow the asbestos fibres to escape easily into the air and, if well maintained and undamaged, are of negligible risk to health. Friable asbestos products, such as loose-fill roofing insulation, can be easily crumbled into dust with fine pressure. This allows asbestos fibres to more easily be released into the air and be inhaled by those in the vicinity. Bonded asbestos products that are damaged or not well maintained may also become friable .
How to reduce the health risks from asbestos products
Many households contain asbestos products but the health risks can be minimised through following some basic steps:
- Painting, enclosing or capping certain asbestos containing products.
- Replacing materials that are damaged, while ensuring that only a licensed asbestos removalist is used.
- Planning ahead to prevent disturbing and releasing asbestos fibres, particularly when renovating or demolishing a structure that may contain asbestos.
- Get advice, if needed, from your local government environmental health officer .
Mr Fluffy – loose fill asbestos insulation
During the 1960s and 1970s loose-fill asbestos was sold as ceiling insulation. A company known as ‘Mr Fluffy’ installed this insulation. This occurred predominantly in the ACT but also in a small number of NSW premises. In August of 2014 the NSW government announced an investigation to establish the number of residential properties that contain loose-fill asbestos material. Free property assessments and testing is currently being conducted in affected areas with residents encouraged to contact Fair trading within NSW. More recently the NSW government has announced a program that gives home owners options such as to sell their home and land to the Government for market value.
Responding to issues related to asbestos is often complex requiring the involvement of multiple areas of government. The Heads of Asbestos Coordination Authorities has been established to improve the response to asbestos in New South Wales and has representatives from relevant government organisations. The Environmental Health Branch, through the Ministry of Health, has an important role in communicating the complexities of health risk and advising on appropriate risk management.
- Leigh J, Davidson , Hendrie L & Berry D (2002). Malignant mesothelioma in Australia 1945–2000. American Journal of Industrial Medicine 41 188–201.
- Cancer Institute NSW (2012). Australian Mesothelioma Registry 2nd Annual Report. Safe Work Australia, Alexandria.
World Health Organization (2000).
- World Health Organization air quality guidelines for Europe, 2nd edition. World Health Organisation, Copenhagen.
- Agency for toxic substances and disease registry (2001). Public health statement for Asbestos. Agency for toxic substances and disease registry, Atlanta USA. http://www.atsdr.cdc.gov/PHS/PHS.asp?id=28&tid=4 accessed 21 January 2015.
- Integrated risk information system (2015). Asbestos (CASRN 1332-21-4). United States Environment protection authority, Washington USA. http://www.atsdr.cdc.gov/PHS/PHS.asp?id=28&tid=4 accessed 21 January 2015.
- Environmental health subcommittee (EnHealth) (2012). Asbestos: A guide for householders and the general public. Australian Health Protection Principal Committee, Canberra.