Estimating asbestos exposure: a comparison of methods

Our plain-English summary of Estimating asbestos exposure: a comparison of methods, by B. Järvholm, A. Sandén (Journal of Occupational Medicine., 1987).

The study

• Authors: B. Järvholm, A. Sandén
• Journal: Journal of Occupational Medicine.
• Published: 1987;29(4):361-3
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000327).

Abstract

The association between pleural plaques and asbestos exposure was investigated in a cross-sectional study of 951 male shipyard workers. Asbestos exposure was estimated by the men themselves and also by an expert panel whose judgment was based only on occupational title. The analysis was restricted to men who had had at least 20 years of exposure and who had not changed jobs during their period of employment in the shipyards. The results showed that there was a much closer correlation between the occurrence of pleural plaques and the men's own estimates of exposure than between the occurrence and the experts' estimates. Contrary to reports of other investigators, the authors found no association between smoking habits and the occurrence of pleural plaques (rate ratio = 1.0, chi 2 (1) = 0.3).

In plain English

This cross-sectional study compared ways of estimating asbestos exposure among 951 male shipyard workers in Gothenburg, Sweden. They came from 3,902 workers examined between 1977 and 1979. Only men with at least 20 years at the shipyard who had not changed jobs were included. Each man answered an exposure questionnaire and had a chest X-ray read for pleural plaques, though 31 men did not rate their exposure level. A panel of technicians, safety engineers and safety stewards separately rated exposure from job titles alone. Plaques were more closely related to time since first exposure than to total exposure time. The men's own ratings showed a dose-response relationship with plaques, but the panel's ratings did not. Welders had the lowest plaque prevalence. Among office workers, 23 of 51 (45%) who had trained in production areas had plaques, versus 18 of the other 51 (35%). The authors found no association between smoking and plaques (rate ratio 1.0, smokers versus nonsmokers). The authors concluded that a worker's own estimate is better in some instances than an expert panel's estimate based only on job title. They noted that chest X-rays often miss plaques.

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: cross-sectional study comparing worker self-estimates and expert job-title estimates of asbestos exposure against pleural plaques on chest X-ray
• Who was studied: 951 male shipyard workers in Gothenburg, Sweden, selected from 3,902 workers who considered themselves asbestos-exposed and took part in a health examination in 1977 to 1979. Included men had at least 20 years of shipyard employment and had not changed jobs. Women, men above retirement age and men exposed to asbestos before shipyard employment were excluded.
• Exposure: Asbestos exposure at shipyards (fiber type not specified). The men rated it themselves by questionnaire (very low, low, heavy, very heavy, plus exposure time), with 31 not answering the exposure-level question. An expert panel separately rated it from 104 job titles using the same four levels.
• Main results:
  • 31 workers did not answer the question rating their own exposure level
  • Pleural plaques appeared much more related to time since first asbestos exposure (latency) than to total exposure time as estimated by the men
  • The men's own four-category exposure estimates showed a dose-response relationship with pleural plaques
  • The expert panel's estimates, using the same categories, showed no dose-response relationship with pleural plaques
  • Welders had the lowest prevalence of pleural plaques among occupational groups
  • Office workers who had worked in production areas during training: 23 of 51 (45%) had pleural plaques
  • The other office workers (who had visited production areas in their jobs): 18 of 51 (35%) had pleural plaques
  • No association between smoking and pleural plaques: Mantel-Haenszel rate ratio 1.0 for smokers versus nonsmokers (chi-square with 1 degree of freedom of 0.3)
• The authors' conclusion: The authors concluded that a worker's own estimate of asbestos exposure is better in some instances than an expert panel's estimate based solely on occupational title, and that smoking is not associated with pleural plaques
• Limitations the authors state:
  • The comparison rests on the assumption that, for similar latency periods, plaque prevalence is associated with asbestos dose
  • Exposure probably varies considerably within the same occupational group. Experts who could interview each man might have been more accurate.
  • Chest X-rays have low sensitivity for pleural plaques, so absence of plaques cannot be taken as a sign of low exposure in an individual

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Pleural Plaques, Habit, rate ratio.

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