Relation between lung function, exercise capacity, and exposure to asbestos cement

Our plain-English summary of Relation between lung function, exercise capacity, and exposure to asbestos cement, by P. Wollmer, L. Eriksson, B. Jonson, et al (British Journal of Industrial Medicine, 1987).

The study

• Authors: P. Wollmer, L. Eriksson, B. Jonson, K. Jakobsson, M. Albin, S. Skerfving, H. Welinder
• Journal: British Journal of Industrial Medicine
• Published: 1987;44(8):542-9
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000367).

Abstract

A group of 137 male workers with known exposure (mean 20 fibre years per millilitre) to asbestos cement who had symptoms or signs of pulmonary disease was studied together with a reference group of 49 healthy industrial workers with no exposure to asbestos. Lung function measurements were made at rest and during exercise. Evidence of lung fibrosis was found as well as of obstructive airways disease in the exposed group compared with the reference group. Asbestos cement exposure was related to variables reflecting lung fibrosis but not to variables reflecting airflow obstruction. Smoking was related to variables reflecting obstructive lung disease. Exercise capacity was reduced in the exposed workers and was related to smoking and to lung function variables, reflecting obstructive airways disease. There was no significant correlation between exercise capacity and exposure to asbestos cement.

In plain English

Researchers at the University of Lund, Sweden, compared lung function in 137 male former workers from an asbestos cement factory with 49 healthy industrial workers not exposed to asbestos, such as lumberjacks and slaughterhouse and food-industry workers. The exposed men were selected from 758 screened former workers because they had breathlessness, crackles in the lungs, X-ray signs of fibrosis, or reduced breathing-test results. The factory used almost exclusively chrysotile asbestos. The exposed men's average cumulative exposure was 19.7 fibre years per millilitre (median 11.8). Lung function was measured at rest and during a bicycle exercise test. Exposed men, especially non-smokers, had reduced lung volumes and stiffer lungs, and higher asbestos exposure was associated with these signs of fibrosis. Exercise capacity was lower in exposed men. It was not significantly correlated with asbestos exposure but was related to smoking and to measures of airflow obstruction. The authors concluded that the fibrosis-producing effect of asbestos dominated and that the airflow obstruction they found mainly reflected how the groups were selected. They cautioned that their findings probably do not apply to exposed workers at large.

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 comparison of lung function at rest and during exercise in a selected group of exposed former workers versus an unexposed reference group, with regression analysis of smoking and cumulative asbestos exposure
• Who was studied: 137 male former workers at an asbestos cement factory with symptoms or signs of lung disease, selected from 758 male former workers screened in a health survey. The reference group was 49 healthy workers (lumberjacks, slaughterhouse and food manufacturing workers) matched for age and smoking habits. No subject was exposed at the time of the study; the mean interval since exposure ended was 13.5 years.
• Exposure: Asbestos cement dust. The asbestos was almost exclusively chrysotile, and the factory operated from 1907 to 1977. In the study group, mean cumulative exposure was 19.7 fibre years per millilitre, the median was 11.8, and the 10th and 90th percentiles were 0.9 and 39.5 fibre years per millilitre.
• Main results:
  • At rest, exposed non-smokers had reduced lung volumes and static lung compliance compared with the reference group. Exposed smokers had significantly reduced total lung capacity and static compliance, and increased lung resistance.
  • Within the study group, asbestos exposure was negatively correlated with lung volumes (TLC, FRC, RV) and static compliance, and positively correlated with elastic recoil pressure at full inspiration. The authors described this as compatible with a fibrogenic effect.
  • Exercise capacity was reduced in both exposed non-smokers and exposed smokers compared with the reference group. Of the 137, 120 completed the exercise test.
  • In the study group, asbestos cement exposure was not significantly correlated with exercise capacity. Exposure was significantly negatively correlated with dynamic lung compliance during exercise (standardised coefficient -0.382, p less than 0.001).
  • Smoking was inversely related to exercise capacity (standardised coefficient -0.176, p less than 0.05) and positively related to functional lung resistance.
  • Exercise capacity was negatively correlated with lung function measures reflecting airflow obstruction. The strongest was functional lung resistance (r = -0.48, p less than 0.001, n = 120). The authors concluded that exercise capacity related more to airflow obstruction than to interstitial fibrosis.
  • Exposed smokers had statistically significant but small abnormalities in gas exchange during exercise: slightly lower arterial oxygen and slightly higher arterial carbon dioxide.
• The authors' conclusion: The authors concluded that the airflow obstruction found in the study group mainly resulted from selection bias, and that the fibrogenic effect of asbestos dominated under the conditions studied. They also stated that smoking was more important for exercise limitation than asbestos exposure at this level.
• Limitations the authors state:
  • The study group was selected for symptoms and signs of lung disease, so the exposure and lung function relation found probably does not apply to the exposed population at large.
  • Because of how the study group was selected, the authors could not estimate the dose-related risk of developing interstitial fibrosis in the working population.
  • Dust measurement data were limited, especially before 1969, and estimating fibre exposure from impinger measurements was uncertain.
  • The study did not rule out an obstructive effect of low-level asbestos exposure, because it used no technique to study the small airways specifically.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Fibrosis, Obstructive Lung Disease.

Related studies

• Lung function impairment as a guide to exercise limitation in work-related lung disorders — J.E. Cotes, J. Zejda, et al. (1988)
• Lung function and exercise performance in smoking and nonsmoking asbestos-exposed workers — D.Y. Sue, A. Oren, et al. (1985)
• Exercise alveolar-arterial oxygen pressure difference in interstitial lung disease — C. Risk, G.R. Epler, et al. (1984)
• Pulmonary function in asbestos cement workers: a dose-response study — M. Finkelstein (1986)
• Effect of induction chemotherapy on lung function and exercise capacity in patients affected by malignant pleural mesothelioma — G. Marulli, F. Rea, et al. (2010)
• Abnormal wasted ventilation fraction and normal pulmonary hemodynamics during exercise in patients with exertional dyspnea — Z. Mohsenifar, H.V. Brown, et al. (1982)

Browse more research in British Journal of Industrial Medicine, or return to medical research.