Asbestos industry and statutory control of its hazards

Our plain-English summary of Asbestos industry and statutory control of its hazards, by Muriel L. Newhouse (1979).

The study

• Author: Muriel L. Newhouse
• Published: In: Carcinogenic Risks: Strategies for Intervention, pp. 59-70, IARC Scientific Publications No. 25, Lyon (1979)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1979 article by Muriel L. Newhouse was a review, not a new study. It traced the history of the asbestos industry and of UK asbestos control rules. The author described the UK Asbestos Regulations of 1931, which said there should be 'no release of dust' but set no dust standard. The author then described the 1969 Regulations, which became operative in 1970, and the hygiene standard used with them. That standard was 2 fibres/ml for chrysotile; for crocidolite, an approved respirator had to be worn unless the process stayed below 0.2 fibres per cc. The author reported that the 2 fibres/ml standard had been attacked: workers with chest complaints had left the factory it was based on, so the true amount of disease was underestimated. The author summarised three earlier studies, one of them the author's own with G. Berry, as showing dose-response relationships for asbestos and cancer. The author also noted a proposed US standard of 0.5 fibres/ml. The author concluded that UK standards must be revised to take cancer risk into account, but that there was still not enough evidence to set standards.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: narrative review of the history of the asbestos industry and of asbestos control regulations, mainly in the UK, with comparison to the USA
• Who was studied: Not a study of a defined group of people. The article reviewed UK and US asbestos regulation from the first factories (about 1880) to the late 1970s, and summarised other investigators' studies of asbestos workers and miners.
• Exposure: Asbestos in general. The article discussed chrysotile, amosite, crocidolite and anthophyllite separately, and also man-made mineral fibres used as substitutes.
• Main results:
  • The author recounted that the Merewether and Price survey of an asbestos textile factory in the East End of London (report published 1930) found a third of the workers affected by asbestosis.
  • According to the author, the 1931 UK Asbestos Regulations stated there should be 'no release of dust' but did not suggest how this could be checked. Medical examinations applied only to workers in certain scheduled jobs.
  • The 1968 hygiene standard for chrysotile dust, quoted in the article, aimed to reduce the risk of contracting asbestosis to 1 percent for an accumulated exposure of 100 fibre-years per cm3. An example given was 2 fibres per cm3 for 50 years.
  • Under the same standard, an approved respirator had to be worn for crocidolite unless the process could be kept below 0.2 fibres per cc, a tenth of the chrysotile standard. The scan prints this as 'C.2'; the article's phrase 'a tenth of the chrysotile standard' of 2 confirms 0.2.
  • The author reported that the new regulations were passed through Parliament in 1969 and became operative in 1970.
  • The author reported Factory Inspectorate dust sampling results. Among larger employers, over 90% of results were below the hygiene standard (the scan prints this as '907'). Nearly 80% of smaller factories achieved the standard. About 1200 factories and workplaces were subject to the regulations.
  • The author reported that nearly 7000 workers had been examined in the UK survey of asbestos workers by the end of 1974.
  • The author reported criticism of the 2 fibres/ml standard. In the factory on which it was based, workers with chest complaints had left the industry, so the true prevalence of disease was underestimated.
  • Summarising Selikoff (1976) on US workers exposed to amosite, the author reported a standardized mortality ratio for lung cancer of 288 in those with only two months' exposure. This rose to a 13-fold excess in those with over three years' exposure.
  • Summarising the author's own earlier study with Berry (1976), at a factory using all three fibre types, the author reported no excess lung cancer mortality for short, light exposures and a five-fold excess in the most severely exposed group. For mesothelioma, a risk remained even in the lowest exposure group.
  • Summarising Liddell et al. (1977) on Canadian chrysotile miners, the author reported that those authors saw no evidence of an excess risk below 300 mpcf-years.
  • The author reported that in the US, the National Institute of Occupational Safety and Health had proposed a standard of 0.5 fibres/ml.
  • The author reported that in 1976 the UK Health and Safety Commission set up an Advisory Committee on Asbestos with members from industry, trades unions, academic medicine and hygiene, and local authorities. It was due to report in 1978.
• The authors' conclusion: The author concluded that the asbestos standards had to be revised to take the cancer risk into account, but that there was still not enough evidence to set standards. Meanwhile, the author suggested that stringent standards be imposed for all types of asbestos.
• Limitations the authors state:
  • The author stated that dust measurements made in the past may be unreliable, and that further deaths may occur in the populations under study.
  • The author stated that current measurements count only fibres longer than 5 micrometres visible in the light microscope. Electron microscopy can detect many more and smaller fibres.
  • The author stated that more studies of pure fibre exposure were needed.
  • The author stated that final proof on whether asbestosis occurs at current exposure levels would not be available for several years.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Crocidolite, Respirator, Dose-response relationship.

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