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 (Archives of Environmental Health, 1973).

The study

• Authors: D.H. Wegman, G.P. Theriault, J.M. Peters
• Journal: Archives of Environmental Health
• Published: 1973;27(2):105-9
• Cited by: 4 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. 002414).

In plain English

This was a cross-sectional survey, requested by a local union, of 57 white male workers at a small northeastern Massachusetts plant making asbestos wall board. The group was 52 of 56 active union members, three retirees and two floor foremen. Workers answered a questionnaire, had their chests listened to, and did breathing tests. The company refused to release its chest x-ray films. With no unexposed comparison group, results were compared with values predicted for normal people of the same age and height. Years worked at the plant stood in for asbestos exposure. Loss of breathing capacity was strongly associated with years of exposure, even allowing for age and height, and more strongly than with years of smoking. Only three of 57 fell below the 60% breathing-test cutoff for obstruction, and the authors judged obstructive disease infrequent. Thirteen had crackling sounds (rales) at the lung bases, associated with years of exposure and lower lung capacity. The authors concluded the loss was restrictive and consistent with asbestosis. They noted that without x-rays, asbestosis could not be definitely diagnosed in individual workers.

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 a local union, with no control group. Lung function was compared with values from prediction equations and analysed by regression.
• Who was studied: 57 white male asbestos workers at a small company in northeastern Massachusetts producing asbestos wall board: 52 of the 56 active members of the bargaining unit, three retirees, and two floor foremen. They were examined in the home of the union president after the authors approached the union in June 1971.
• Exposure: Work producing asbestos wall board from raw materials. No fiber type is named. With no individual dust measurements, length of employment was used as the measure of asbestos exposure. The mean was 13.1 years; the text says workers had worked between six months and 33 years.
• Main results:
  • In partial correlation analysis of observed minus expected lung function, duration of exposure correlated with FVC (r = -0.63, p less than .001) and with FEV1 (r = -0.54, p less than .001). Years smoked correlated significantly only with FEV1 (r = -0.25, p less than .05; for FVC r = -0.07, not significant).
  • In stepwise regression for both FEV1 and FVC, duration of exposure was a much more important predictor than age or years smoked. For FVC, only height and duration of exposure were significant predictors.
  • Age was highly correlated with duration of exposure (r = 0.78). After lung function was standardized for age and height using the Kory prediction equation, duration of exposure still significantly predicted the remaining loss in FVC and FEV1.
  • The mean FEV1/FVC ratio was 76.3% (99% confidence limits 72.8% to 79.8%). Only three of the 57 workers had a ratio below 60%, which the article calls generally accepted evidence of obstructive disease. The authors concluded that obstructive disease was not frequent in this population.
  • Thirteen of the 57 workers had "asbestotic" rales, meaning fine crackles at a lung base that did not clear with coughing. Rales were associated with duration of exposure (chi-square 14.9, P less than .001) but not with years smoked (chi-square 5.3, not significant).
  • Workers with rales had lower FVC. Their actual FVC was 3.139 against a predicted 4.015, a difference of 0.876. Workers without rales had an actual FVC of 4.523 against a predicted 4.561, a difference of 0.038 (t = 3.492, P less than .001).
  • Symptoms: 18 men reported shortness of breath, 18 wheezing, 16 cough, and 4 pleuritic pain. Results for shortness of breath and cough were inconclusive. The authors suggested that a report of wheezing may not differentiate the type of respiratory disease.
  • A 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. Twelve earlier evaluations (1952 through 1968) averaged 1.9 million particles per cubic foot.
• 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, and that union sponsorship provided enough information to show disease was present.
• Limitations the authors state:
  • Without the chest x-ray films, a definite diagnosis of asbestosis in individual workers was not possible.
  • No control group was available, because the entire union population worked with asbestos.
  • No individual dust measurements were available, so length of employment substituted for exposure.

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Lung Disease.

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