Hygiene standards for asbestos

Our plain-English summary of Hygiene standards for asbestos, by S.A. Roach (The Annals of Occupational Hygiene, 1970).

The study

• Author: S.A. Roach
• Journal: The Annals of Occupational Hygiene
• Published: 1970;13(1):7-15
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This paper, first presented at a 1969 conference on asbestos exposure during brake and clutch maintenance, described how the British Occupational Hygiene Society's Sub-committee on Asbestos derived new hygiene standards for airborne chrysotile dust, and compared them with American standards. The standards were based on a medical and environmental study of 290 men employed at an English asbestos textile factory between 1933 and 1966. Exposure was expressed in fibre years/cm3, the average concentration of fibres longer than 5 µm (membrane filter counts) multiplied by years of exposure. Concentrations had ranged from 1 to 27 fibres/cm3 over 10 to 33 years. The author explained the dose-response principles involved and argued that there is no single threshold. A curve fitted to the prevalence of basal rales indicated that, for an accumulated exposure of 100 fibre years/cm3, the risk of early clinical signs of asbestosis would probably be less than 1 per cent. This corresponded to a 3-monthly average of 2 fibres/cm3 over a 50-year working life. The American limit of 5 million particles/ft3, set in 1938, was described as about 17 times higher, and the paper summarised the ACGIH's 1968 proposal for a time-weighted limit equivalent to 12 fibres/cm3. The Sub-committee had not decided whether the standards suited amosite or crocidolite, or protected against lung cancer or mesothelioma. The author concluded that deciding what level of dust control is acceptable was more uncertain than the exposure-risk relationship, and that more information on control costs was needed.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This conference paper, first presented in March 1969, explained how the British Occupational Hygiene Society's hygiene standard for airborne chrysotile asbestos was worked out. It did not report a new study. The standard rested on an earlier study (Lane and colleagues, 1968) of 290 men employed at an asbestos textile factory in England between 1933 and 1966. Their exposures ranged from 1 to 27 fibres per cubic centimetre over 10 to 33 years. In those data, crepitant basal rales, described as the earliest clinical sign of asbestosis, became steadily more common as exposure rose. From a fitted curve, the risk of early clinical signs at an accumulated exposure of 100 fibre-years per cubic centimetre was judged probably less than 1 per cent. That equals, for example, 2 fibres per cubic centimetre for 50 years. The author wrote that the American standard then in force, for 8-hour averages, was 17 times higher than the British standard for 3-monthly averages. The sub-committee had found the hardest question was what level of dust control was acceptable. The committee had not decided whether the standard suited amosite or crocidolite, or protected against lung cancer or mesotheliomas.

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: Conference paper (commentary) describing how a hygiene standard for chrysotile asbestos was derived from an earlier study, and comparing it with the American standard; no new data collected
• Who was studied: The standard was based on an earlier study (Lane et al., 1968) of 290 men employed at an asbestos textile factory in England, 1933-1966
• Exposure: Airborne chrysotile dust at the textile factory. Fibres longer than 5 microns were counted on membrane filters. Exposures ranged from 1 to 27 fibres per cubic centimetre over 10 to 33 years and were expressed as fibre-years per cubic centimetre.
• Main results:
  • In the textile factory workers, the prevalence of crepitant basal rales (the earliest clinically demonstrable lung effect of asbestos) rose steadily with dust exposure. Only groups with near-zero exposure showed zero prevalence.
  • From the fitted exposure-response curve, at an accumulated exposure of 100 fibre-years per cubic centimetre the risk of early clinical signs was judged probably less than 1 per cent (for example, 2 fibres per cubic centimetre for 50 years, 4 for 25 years, or 10 for 10 years)
  • The British standard recommends that accumulated chrysotile exposure not exceed 100 fibre-years per cubic centimetre, which refers essentially to a 3-month working-hours average of 2 fibres per cubic centimetre
  • The then-current American standard for 8-hour averages was 17 times higher than the British standard for 3-monthly averages. A revision of the American standard had been proposed.
  • The committee found the evidence that short periods of very high concentration were disproportionately important was not conclusive
• The authors' conclusion: The author reported that the sub-committee found knowledge of the exposure-risk relationship was not the greatest uncertainty. The harder problem was deciding what level of dust control was acceptable, and more information was needed on the costs of dust control.
• Limitations the authors state:
  • The committee had not decided whether the chrysotile standard was suitable for amosite or crocidolite, or whether it protected against lung cancer or mesotheliomas
  • The author stated that present information was very imprecise, especially on the practical consequences of particular standards
  • The author stated that meeting a hygiene standard would limit the risk but was unlikely to reduce it to zero

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Chrysotile, Dose-response relationship, Amosite, Crocidolite, Lung Cancer, Mesothelioma, Dust Control.

Related studies

• The hygiene standard for chrysotile asbestos — J. Peto (1978)
• Technical implementation of the new asbestos regulations — S. Luxon (1970)
• Technological feasibility of the 2 fibers/cc asbestos standard in asbestos textile facilities — R.A. Curtis, P.H. Bierbaum (1975)
• Revising the British Occupational Hygiene Society asbestos standard: 1968-1982 — M. Greenberg (2006)
• Industrial hygiene and occupational health studies in Australian (New South Wales) shipyards — A. Bell (1976)
• Industrial hygiene perspectives in control of asbestos exposure — W. Reitze (1979)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.