Hygiene Standards - Theory and Application

Our plain-English summary of Hygiene Standards - Theory and Application, by G. Berry (1973).

The study

• Author: G. Berry
• Published: BIOLOGICAL EFFECTS OF ASBESTOS (J.C. WAGNER, EDITOR), LYON: IARC SCIENTIFIC PUBLICATIONS, VOLUME 8, PP. 145-149 (1973)
• 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 was a discussion paper, not a new study. The author considered how an acceptable level of asbestos dust in workplace air, called a hygiene standard, should be set. The author argued that a completely safe 'threshold' cannot be upheld in practice. One reason given was that if no disease were found among 1000 people at a certain dose, it could only be stated with reasonable certainty that the risk was less than 3 in 1000. An older US asbestos textile survey found no clear-cut asbestosis in 108 workers with mean dust of about 3 million particles per cubic foot, so the author judged the asbestosis risk at that level probably below 3%. British Occupational Hygiene Society data from a chrysotile textile factory gave an estimated 112 fibre years per cubic centimetre for a 1% risk of basal rales (crackling lung sounds). The author noted the group was selected because some workers had left, which would bias the conclusions if leavers differed in susceptibility. The author concluded that a standard can be set only by balancing health risks against benefits, and that data were scarce.

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: Theoretical and methodological discussion paper on setting hygiene standards, illustrated with previously published data. It is not an original study.
• Who was studied: Illustrative data only. The first set came from an earlier US asbestos textile industry survey (Dreessen et al., 1938). It covered 108 workers exposed below a stated dust level, and the cutoff value is unreadable in the scan. The second set came from British Occupational Hygiene Society (1968) data on two groups of men in an asbestos textile factory in 1966 who had worked there at least 10 years.
• Exposure: Chrysotile asbestos dust in a textile factory. Group 1 did fiberising, carding and spinning. Group 2 did weaving and plaiting, with lower dust levels. Dose was taken as cumulative exposure: length of exposure multiplied by mean dust concentration.
• Main results:
  • The author argued that a threshold cannot be determined from epidemiological data. If no cases were seen among 1000 people at risk at a certain dose, it could only be stated with reasonable certainty that the risk was less than 3 in 1000.
  • Dreessen et al. (1938) found no clear-cut asbestosis in 108 workers exposed below a stated dust level, whose mean dust concentration was about 3 mppcf. From this the author deduced that the asbestosis risk at a concentration of 3 mppcf was probably less than 3%. The author said this is different from concluding that a safe threshold exists.
  • For the chrysotile textile factory data, a dose-response curve for recorded basal rales, assuming a log-normal distribution, gave a satisfactory fit.
  • The dose giving a 1% risk of basal rales was estimated at 112 fibre years per cubic centimetre. This implied a concentration of about 2 fibres per cubic centimetre over a working lifetime.
  • Because of error in the estimate, the risk at 112 fibre years per cubic centimetre could reasonably be as high as 3%. To be 95% certain the risk did not exceed 1%, the dose would have to be no more than 51 fibre years per cubic centimetre.
• The authors' conclusion: The author concluded that a hygiene standard can be set only by balancing health risks against the benefits of the material. The author also concluded that there was a paucity of data on which to base a rational choice of standard for asbestos.
• Limitations the authors state:
  • The factory data were not from a representative sample. They came from men in one mill at one time, and the group was the result of selection because some workers had left the industry. If those who left differed in susceptibility to basal rales from those who stayed, the conclusions would be biased accordingly.
  • The British Occupational Hygiene Society had to base its standard on only one set of data.

Topics

Medical terms in this study, explained in our Lexicon: Million Particles per Cubic Foot (mppcf), Chrysotile.

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