Asbestosis, pulmonary symptoms and functional impairment in shipyard workers

Our plain-English summary of Asbestosis, pulmonary symptoms and functional impairment in shipyard workers, by K.H. Kilburn, R. Warshaw, J.C. Thornton (Chest, 1985).

The study

• Authors: K.H. Kilburn, R. Warshaw, J.C. Thornton
• Journal: Chest
• Published: 1985;88(2):254-9
• Cited by: 15 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. 000483).

Abstract

A group of 339 male shipyard workers responded to an invitation via shipyards, unions, and news media to be studied for the presence of asbestosis and its functional effects. Of these, 288 were white or black, had begun working in shipyards at least 20 years earlier, and had satisfactory chest x-ray film findings; 257 underwent spirometric testing, and 199 had single-breath diffusing capacities for carbon monoxide (Dsb) determined. There were radiographic signs of asbestosis in 64 percent. Of these, 28 percent had parenchymal disease only, 37 percent had pleural disease only, and 35 percent had both. There was pleural calcification in 9 percent. In only 14 (8 percent) was the profusion of opacities greater than 1/1 by the International Labour Organization's criteria. Age was closely related to the duration of exposure to asbestos. Thus, 87 percent of the workers who had asbestosis were born from before 1900 to 1910, 70 percent of those born in 1911 to 1920 had asbestosis, 62 percent of those born in 1921 to 1930 had the disease, and 31 percent of those born in 1931 to 1940 had signs of asbestosis. Function in nonsmokers was not significantly different from the reference population except for alveolar volume; ex-smokers had significantly reduced forced expiratory volume in one second, flow rates, Dsb, and alveolar volume. The forced vital capacity and thoracic gas volume were normal. Shipyard workers who smoked resembled reference smokers except for significantly reduced alveolar volume. These shipyard workers had minimal to moderate asbestosis with much pleural disease and little functional impairment when compared to a smoking-specific reference population.

In plain English

This was a pilot study of volunteer male shipyard workers from Long Beach, California, who had begun shipyard work at least 20 years earlier. The authors used questionnaires, physical examinations, chest X-rays read by three physicians under International Labour Organization (ILO) criteria, and breathing tests. They compared the workers with 595 white Michigan men grouped by smoking status. Among 288 white or black workers, 64 percent had X-ray signs of asbestos-related disease. Of all 288, 24 percent had pleural changes only, 18 percent had irregular opacities in the lung tissue only, 23 percent had both, and 9 percent had pleural calcification. Workers reported wheezing and breathlessness far more often than the Michigan men did. Against men of the same smoking status, alveolar volume was significantly reduced among the nonsmokers, the ex-smokers and the current smokers. Other reductions in lung function were significant only in ex-smokers. The authors concluded there was little functional impairment beyond that attributable to smoking. They cautioned that the volunteer sample may not be representative and that the small reductions should not be reassuring.

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 pilot study of volunteers (questionnaires, physical examination, chest X-rays, lung function tests), compared with a smoking-specific reference population of Michigan men
• Who was studied: Male shipyard workers (Long Beach, California shipyards) who responded to invitations via shipyards, unions and news media; 288 white or black men were analyzed for X-rays, 257 had spirometry and 199 had diffusing capacity measured. They were compared with 595 white Michigan men aged 18 to 85. Female workers and family members were also recruited but are not reported in these results.
• Exposure: Shipyard work with asbestos exposure, having begun at least 20 years earlier; fiber types and doses are not given. The authors also mention fumes from welding, cutting, burning and painting as possible contributors to wheezing.
• Main results:
  • 64 percent (185 of 288) of the male shipyard workers had chest X-ray signs of asbestos-related disease, pleural or parenchymal
  • Pleural thickening and plaques were present in 46 percent of the 288 workers, and pleural calcification in 9 percent
  • Of the 288 workers, 18 percent had parenchymal irregular opacities alone and 23 percent had both pleural and parenchymal disease. Table 2 shows 24 percent with pleural disease only.
  • In only 14 workers (8 percent, as printed) was the profusion of opacities greater than 1/1 by ILO criteria
  • Shortness of breath on climbing two flights of stairs was reported by 54 percent of nonsmoking, 59 percent of ex-smoking and 66 percent of currently smoking shipyard workers, compared with 0.4, 4 and 3 percent of Michigan men in the same smoking groups
  • Wheezing was reported by 32 percent of nonsmoking, 43 percent of ex-smoking and 68 percent of currently smoking shipyard workers, compared with 1, 8 and 13 percent of Michigan men in these groups
  • Compared with smoking-specific reference groups, alveolar volume was significantly reduced in all shipyard groups. Differences were minus 0.478 (p 0.008) in nonsmokers, minus 0.624 (p 0.0001) in ex-smokers and minus 0.417 (p 0.02) in current smokers.
  • Only ex-smokers had significant differences in spirometry and diffusing capacity versus reference ex-smokers, for example FEV1 minus 0.23 (p 0.01) and diffusing capacity minus 2.40 (p 0.005). Total thoracic gas volumes did not differ from reference groups.
• The authors' conclusion: The authors concluded that, given the slight to moderate extent of asbestos-induced disease on X-ray, there was little evidence of functional impairment beyond that attributable to cigarette smoking. They added that the relatively small reductions should not be reassuring and that further studies are needed.
• Limitations the authors state:
  • The study was a pilot study of a volunteer sample, and how representative it is of other workers is somewhat problematic
  • Results may be confounded to some extent by sampling and survivorship bias
  • There were too few nonsmokers for statistical comparisons across degrees of asbestosis
  • The tests do not show whether exercise capacity was impaired

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Shipyards and maritime work.

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Pleural Calcification.

Related studies

• Pulmonary functional impairment and symptoms in women in the Los Angeles Harbor area — K.H. Kilburn, R. Warshaw, et al. (1985)
• Signs of asbestosis and impaired pulmonary function in women who worked in shipyards — K.H. Kilburn, R. Warshaw, et al. (1985)
• Airway obstruction in asbestos-exposed shipyard workers: with and without irregular opacities — K.H. Kilburn, R.H. Warshaw (1990)
• Pulmonary functional impairment from years of arc welding — K.H. Kilburn, R.H. Warshaw (1989)
• Correlation between respiratory symptoms and pulmonary function in asbestos-exposed workers — C.A. Brodkin, S. Barnhart, et al. (1993)
• Asbestos disease in family contacts of shipyard workers — K.H. Kilburn, R. Lilis, et al. (1985)

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