Worker-Sponsored Survey for Asbestosis: Detection of Occupational Lung Disease Without a Control Group

Our plain-English summary of Worker-Sponsored Survey for Asbestosis: Detection of Occupational Lung Disease Without a Control Group, by D. H. Wegman, G. P. Theriault, J. M. Peters (1973).

The study

• Authors: D. H. Wegman, G. P. Theriault, J. M. Peters
• Published: Arch Environ Health, Vol 27, Aug 1973, pp. 106-109
• Type of article: Journal article
• 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

A local union requested this survey at a small northeastern Massachusetts plant making asbestos wall board. The authors examined 57 white male workers by questionnaire, breathing tests and limited physical examination. The company refused to release chest x-ray films, and there was no control group. Breathing results were instead compared with predicted normal values, with length of employment as the exposure measure. Lung function loss was more closely related to length of employment than to age or years smoked. The mean ratio of air exhaled in the first second to total air exhaled (FEV1/FVC) was 76.3%, with 99% confidence limits of 72.8% to 79.8%. Only three of 57 workers fell below 60%, so the authors judged obstructive disease infrequent. Thirteen had crackling lung sounds (rales), which were associated with length of employment and lower lung capacity. The authors concluded the workers had restrictive lung function loss consistent with asbestosis, though without x-rays a definite diagnosis in individual workers was not possible. An unannounced 1972 state inspection found 6.3 to 11.5 fibers per milliliter at work stations.

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 survey of one workforce, sponsored by the union, without a control group; breathing results compared with predicted normal values
• Who was studied: 57 white male asbestos workers at a small asbestos wall board plant in northeastern Massachusetts: union members, three retirees and two floor foremen
• Exposure: Work producing asbestos wall board from raw materials. No individual dust measurements were available, so length of employment (six months to 33 years) was used as the measure of asbestos exposure. Fiber type is not named.
• Main results:
  • Smoking among the 57 workers: 12 had never smoked, 13 had stopped smoking, and 32 were current smokers.
  • In regression analysis of both breathing measures (FEV1 and FVC), duration of exposure was a stronger predictor of lung function than age or years smoked.
  • The mean ratio of FEV1 to FVC in the study population was 76.3%, with 99% confidence limits of 72.8% to 79.8%.
  • Only three of the 57 workers had an FEV1 to FVC ratio below 60%, the level the authors treat as evidence of obstructive disease.
  • Thirteen of the 57 workers had the fine crackling lung sounds the authors call 'asbestotic' rales.
  • Workers with rales averaged 16 years older than those without and had worked 13 years longer.
  • The authors reported that rales were highly significantly associated with duration of exposure and with loss in FVC.
  • Of the 57 workers, 18 reported shortness of breath, 18 reported wheezing, and 16 reported cough.
  • Twelve plant dust evaluations from 1952 through 1968 showed an average of 1.9 million particles per cubic foot, within the old limit of 5.
  • An unannounced state inspection in winter 1972, using the fiber count method, found 6.3 to 11.5 fibers per milliliter at the work stations tested. All counts were above the new standard of 5 fibers per milliliter.
• The authors' conclusion: The authors concluded that this population had significant loss of lung function that was restrictive, not obstructive, and consistent with asbestosis. They also concluded that occupational disease can be detected by a cross-sectional study without a control group.
• Limitations the authors state:
  • Because the x-ray films were not available, a definite diagnosis of asbestosis in individual workers was not possible.
  • No dust measurements were available for individual workers, so length of employment stood in for exposure.
  • The authors questioned whether the reported dust counts represented usual exposure. Employees suggested that work areas had been cleaned and production lowered on inspection days.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Lung Disease, Chest X-Ray, FEV1/FVC Ratio, Restrictive Lung Disease.

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