Dose-response relationships for asbestos-related disease; implications for hygiene standards. Part I. Morbidity

Our plain-English summary of Dose-response relationships for asbestos-related disease; implications for hygiene standards. Part I. Morbidity, by G. Berry, H.C. Lewinsohn (Annals of the New York Academy of Sciences, 1979).

The study

• Authors: G. Berry, H.C. Lewinsohn
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:185-94
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004028).

Summary of the article

The authors related measured asbestos dust levels to morbidity in an asbestos textile factory in the north of England, extending a study included in the British Occupational Hygiene Society's 1968 report. A total of 392 men met the inclusion criteria: more than 10 years' work in scheduled areas since 1933 by the end of 1972, excluding men who left before June 30, 1966. Of these, 197 were first employed in 1951 or later, and 13 men were later excluded. Most asbestos processed was chrysotile, with some crocidolite up to 1968. Each man's yearly exposure was estimated from his job history and static dust sampling. Measured fiber counts were available from 1961, converted particle counts from 1951 to 1960, and estimated levels before 1951. The authors assessed medical records, chest radiographs read by four readers, and lung function. Crepitations were heard in 22% of men, compared with 6% in the 1966 study. There were 58 cases of possible asbestosis, 47 of them since mid-1966. Their incidence was compatible with a linear relationship with cumulative exposure. Among men first employed after 1950, forced expiratory volume fell by 12.1% and forced vital capacity by 10.6% per 100 fiber-years/cm3. For 40 years' exposure at the UK standard of 2 fibers/cm3, predicted prevalence of possible asbestosis ranged from 4% to 14%, depending on the exposure measure. The authors concluded that there was considerable doubt about the likely consequences of the current hygiene standard.

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 was a morbidity study of men at an asbestos textile factory in the north of England. It extended a study in the British Occupational Hygiene Society's 1968 report. It covered men who by the end of 1972 had worked over 10 years in scheduled areas since 1933, excluding those who left before June 30, 1966; 197 started in 1951 or later. Most asbestos processed was chrysotile, with some crocidolite up to 1968. Crepitations were heard in 22% of men: 17% of those employed at the end of 1972, 29% of those who had left. There were 58 cases of possible asbestosis. Among men first employed after 1950, forced expiratory volume, expressed as a percentage of the value predicted for age and height, was significantly associated with cumulative exposure, with a reduction of 12.1% per 100 fiber-years/cm³. Estimated prevalence of possible asbestosis after 40 years at the UK standard of 2 fibers/cm³ was 4% to 14%, depending on assumptions about dust elimination. The authors noted that possible asbestosis is not specific to asbestos and that other occupations probably contributed to some signs. The authors concluded there was considerable doubt about the likely consequences of the current hygiene standard.

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: Morbidity study of workers at a single asbestos textile factory, extending an earlier factory survey; exposure estimated from job histories and static dust sampling
• Who was studied: Men who by the end of 1972 had worked more than 10 years in scheduled areas of an asbestos textile factory in the north of England since 1933, excluding those who left before June 30, 1966. Table 1 appears to give 379 men for the present study (241 still employed at the end of 1972, 138 who had left), but the totals are garbled in the scan. 197 were first employed in 1951 or later.
• Exposure: Mainly chrysotile, with some crocidolite processed up to 1968; crocidolite exposure could not be separated. Exposure was estimated for each man and year from static sampling. These were fiber counts from 1961, thermal precipitator counts converted to fiber counts for 1951 to 1960, and estimated levels before 1951.
• Main results:
  • Crepitations were heard in 22% of all men in the present study: 17% of workers still employed at the end of 1972 and 29% of those who had left (40 of 138). The 1966 survey had recorded 6%.
  • There were 58 cases of possible asbestosis, 47 of them since mid-1966. Incidence since 1966 plotted against cumulative exposure up to 1966 was compatible with a linear relationship through the origin. There was no statistically significant difference between men first employed before 1951 and those first employed after 1950.
  • Among men first employed after 1950, forced expiratory volume, expressed as a percentage of the value predicted for age and height, was significantly associated with cumulative exposure. The reduction was 12.1% per 100 fiber-years/cm³. Forced vital capacity was also significantly associated. The reduction in transfer factor was not statistically significant, though the authors described it as large enough to be important.
  • Among the 197 men first employed after 1950, chest radiographs showed small irregular opacities of category 0/0 in 122 (62%), 0/1 in 46 (23%), 1/0 in 18, 1/1 in six (3%), and 1/2 or above in five (3%).
  • Among men first employed after 1950, two or more of four readers recorded pleural thickening in 34 men. In nine of them it was bilateral.
  • The estimated prevalence of possible asbestosis after 40 years' exposure at the UK standard of 2 fibers/cm³ was 4% using cumulative exposure and 14% assuming no elimination of dust from the lungs.
  • Of 13 men who started after 1950 and had possible asbestosis, five had previously worked in the cotton industry.
• The authors' conclusion: The authors concluded that, until better data are available, there is considerable doubt about the likely consequences of the current hygiene standard. They regarded possible asbestosis as significant disease relevant to hygiene standards.
• Limitations the authors state:
  • No dust measurements existed before 1951. Levels for 1933 to 1950 were assumed and are probably underestimates.
  • The study population could not be divided into men exposed and not exposed to crocidolite.
  • Men who left before mid-1966 were excluded, causing a bias that is largest for men who started before 1951.
  • Only 60% of men who had left the factory accepted the invitation to a medical examination.
  • Static sampling could not account for individual work-styles. The authors said such errors flatten the dose-response curve and exaggerate risk at low levels.
  • Possible asbestosis is based on indices not specific to asbestos exposure, and false positives exaggerate risk at low levels.
  • Some signs observed were probably at least partly due to other occupations.
  • Predictions for a working life at 2 fibers/cm³ are extrapolations from shorter exposures (average 16 years) at higher levels. Few data relate to more than seven years after the end of exposure.
  • Part of the rise in crepitations may reflect a change of observer, since the factory medical officer retired and was replaced in 1967.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Dose-response relationship, Chrysotile, Crocidolite, Chest X-Ray, Cumulative Exposure, Fiber Year.

Related studies

• Dose-response relationships for asbestos-related disease: implications for hygiene standards. Part II. Mortality — J. Peto (1979)
• Fiber burden and asbestos-related lung disease: determinants of dose-response relationships — M.R. Becklake, B.W. Case (1994)
• Asbestos exposure and benign asbestos diseases in 772 formerly exposed workers: dose-response relationships — G. Mastrangelo, M.N. Ballarin, et al. (2009)
• A study of dose-response relationships for asbestos associated disease — M.M. Finkelstein (1985)
• Risk Analysis Implications of Dose-Response Thresholds for NLRP3 Inflammasome-Mediated Diseases: Respirable Crystalline Silica and Lung Cancer as an Example — L.A.T. Cox (2019)
• The hygiene standard for chrysotile asbestos — J. Peto (1978)

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