Exercise performance and functional impairment in asbestos-exposed workers

Our plain-English summary of Exercise performance and functional impairment in asbestos-exposed workers, by J. Pearle (Chest, 1981).

The study

• Author: J. Pearle
• Journal: Chest
• Published: 1981;80(6):701-5
• Cited by: 18 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. 000766).

Abstract

Eighty-eight shipyard workers with extensive asbestos exposure were evaluated in terms of dyspnea, smoking history, x-ray film abnormalities, static pulmonary function, and exercise performance. Pulmonary function abnormalities and roentgenographic pleuropulmonary disease were more frequent in smokers. Significant dyspnea was present in 41 percent of the workers and did not correlate with smoking history, pulmonary function, or exercise performance. Despite this high frequency of dyspnea, 70 percent of all workers had normal exercise tolerance by history of exercise testing. Of the 26 workers with exercise impairment, only nine had pulmonary mechanical or gas exchange limitation. Two of these workers had asbestosis, while the other had airways obstruction without asbestosis. The prevalence of both asbestosis and asbestos-related exercise impairment in this population was 2.3 percent.

In plain English

This study examined 88 male shipyard workers referred to UCLA Medical Center for suspected asbestos-related lung disease. Each had documented asbestos dust exposure lasting 7 to 43 years (mean 23.6). Fiber types were not named. Workers had breathing tests, chest x-rays, a graded history of breathlessness (dyspnea) and, where indicated, treadmill exercise testing. Thirty-six of 87 (41 percent) reported grade 2 or 3 dyspnea, at roughly similar rates in nonsmokers and smokers. Airway obstruction was found in 17 (30 percent) of 56 heavy smokers, compared with one of 21 nonsmokers. Of 86 workers classified, 60 had normal exercise tolerance. Of the 26 who were impaired, nine were limited by lung problems (eight by airway obstruction, one by gas exchange). The rest had heart disease, deconditioning, physical disability or unclear causes. Only two of the 88 workers (2.3 percent) met the study's criteria for asbestosis, and both were exercise-impaired. The author concluded that asbestosis and asbestos-related exercise impairment were remarkably low in this referred group. The author also noted that studying referred workers might have biased the findings toward more symptoms or disease.

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 clinical evaluation of workers referred for suspected asbestos-related lung disease (no unexposed comparison group); groups compared by smoking history
• Who was studied: 88 male shipyard workers referred to UCLA Medical Center (Los Angeles); mean age 56.72 years; 21 nonsmokers, 11 light smokers (0-9 pack-years), 56 heavy smokers (10 or more pack-years); study dates not given
• Exposure: Asbestos dust in shipyard work (occupations such as electrician, pipefitter, boilermaker), 7 to 43 years (mean 23.6 years); fiber types not specified; the author notes many were exposed only indirectly rather than handling asbestos directly
• Main results:
  • 36 of 87 workers (41 percent) reported grade 2 or 3 dyspnea
  • Grade 2 or 3 dyspnea was roughly similar across smoking groups: nonsmokers 10 (48 percent), light smokers 5 (45 percent), heavy smokers 21 of 55 (38 percent)
  • Airway obstruction was found in 17 (30 percent) of the heavy smokers, compared with one nonsmoker and no light smokers; the difference was reported as significant
  • Reduced diffusing capacity (DLco) was found in no nonsmokers, one light smoker, and 11 (20 percent) of heavy smokers; the difference was reported as significant
  • Among all workers, grade 2 or 3 x-ray pleural disease was seen in 19 (22 percent) and grade 2 or 3 parenchymal (lung tissue) disease in 8 (9 percent). The author reported these as more common in smokers; in Table 1 only the parenchymal differences are marked significant (0 of 21 nonsmokers, 3 of 11 light smokers, 5 of 56 heavy smokers).
  • 70 percent of workers had normal exercise tolerance by history or by exercise testing (60 of 86 classified in Table 3)
  • 47 percent of workers with grade 2 or 3 dyspnea, and 55 percent of those with any dyspnea, had normal exercise tolerance
  • Of the 26 exercise-impaired workers, nine had a lung-related limitation (8 airway obstruction, 1 gas exchange). The others were limited by deconditioning (9), cardiac disease (3), physical impairment (2) or unclear factors (3).
  • Of 55 workers with normal static lung function including DLco, 46 had normal exercise tolerance. The other nine were impaired, but none because of lung abnormalities.
  • 2 of 88 workers (2.3 percent) met the study's criteria for asbestosis
  • Both workers with asbestosis were exercise-impaired: one by gas-exchange abnormalities (with a history of systemic lupus erythematosus) and one by severe airways obstruction
• The authors' conclusion: The author concluded that the prevalence of asbestosis and asbestos-related exercise impairment, even in a referred population, was remarkably low. Exercise tolerance was usually normal despite frequent dyspnea, and most impaired workers had non-lung limitations. In workers without asbestosis, lung impairment was almost always due to airway obstruction, which the author said rarely occurs without cigarette smoking.
• Limitations the authors state:
  • Workers were referred rather than drawn from a whole population, which might have biased findings toward more symptoms or disease
  • The data could not rule out a combined (synergistic) effect of asbestos exposure and smoking on airway obstruction
  • The data were insufficient to show that a normal DLco rules out lung-related exercise impairment in workers with a restrictive defect
  • Only one worker had a combined restrictive-obstructive defect, so no generalization was possible for that group

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, Dyspnea.

Related studies

• Role of exercise testing in assessing functional respiratory impairment due to asbestos exposure — J. Howard, Z. Mohsenifar, et al. (1982)
• 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)
• Spiroergometric parameters at maximal exercise testing assessed functional respiratory impairment in asbestos-induced fibrosis — J. Schneider, R. Arhelger, et al. (2014)
• Evaluation of breathlessness in asbestos workers. Results of exercise testing — P. Agostoni, D.D. Smith, et al. (1987)
• Pulmonary functional impairment from years of arc welding — K.H. Kilburn, R.H. Warshaw (1989)

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