Radiological evidence of asbestos disease among ship repair workers

Our plain-English summary of Radiological evidence of asbestos disease among ship repair workers, by I.J. Selikoff, W.J. Nicholson, R. Lilis (American Journal of Industrial Medicine, 1980).

The study

• Authors: I.J. Selikoff, W.J. Nicholson, R. Lilis
• Journal: American Journal of Industrial Medicine
• Published: 1980;1(1):9-22
• Cited by: 28 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. 000862).

Abstract

Asbestos materials are now infrequently used in new ship construction. However, significant amounts were used in vessels constructed before 1975. As a consequence, for the next 30 or more years, the potential for asbestos exposure in the repair of such vessels will remain. We studied 286 workers who were 30 or more years from onset of employment in ship repair work. Eighty-six percent had radiological evidence of asbestosis, and five instances of previously undiagnosed lung cancer were found. This suggests that unless industrial hygiene precautions are taken in the future repair of vessels that have been built with asbestos, we will add additional decades to the legacy we already face as the result of uncontrolled shipyard exposures of the past.

In plain English

The authors examined union members at a shipyard limited to ship repair. All were 20 or more years from the start of their shipyard employment. Of those invited, 139 active and 147 retired workers were examined in February 1979; 284 chest x-rays were analyzed. The authors reported that 86.3% had radiological evidence of pneumoconiosis. These were largely small irregular opacities and pleural changes, which the authors called characteristic of asbestos exposure. Thirty-nine of 284 (13.7%) had normal films. Abnormal films were found in 25 of 37 men (67.6%) 20 to 29 years from first employment and 170 of 192 (88.5%) 30 to 39 years from first employment. Results were almost identical among 185 men whose shipyard work was confined to this yard. Among all 284 workers with analyzable x-rays, cigarette smoking history made no appreciable difference to the prevalence of x-ray abnormalities. Of 81 men with abnormal x-rays who knew the result of an x-ray from the previous two years, 57 had been unaware of any abnormality. Five previously undiagnosed lung cancers were found. The authors concluded that ship repair workers had a significant risk of asbestosis.

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 medical examination (health survey) of shipyard workers, with chest x-rays read using the ILO U/C classification
• Who was studied: Active and retired union members at a ship repair yard, all 20 or more years from onset of shipyard employment. 179 of 329 eligible active workers and 284 of 490 eligible retired workers were invited. 139 active and 147 retired men (286 total) were examined February 24-27, 1979. 284 x-rays were available for analysis.
• Exposure: Direct and indirect asbestos exposure during ship repair work. Examples given include removing asbestos material from high temperature lines, cutting asbestos cement panels, using woven asbestos blankets for heat shielding, cleaning up asbestos debris, and working near insulation work. No fiber type is named.
• Main results:
  • Of 284 men with readable x-rays, 39 (13.7%) had normal films. 86.3% had radiological evidence of pneumoconiosis: 90 had parenchymal fibrosis alone, 21 had only pleural abnormalities, and 134 had both.
  • The abnormalities were largely small irregular parenchymal opacities and pleural changes, which the authors described as characteristic of asbestos exposure.
  • The proportion with abnormal films rose with time since starting shipyard work. It was 25 of 37 (67.6%) at 20 to 29 years, 170 of 192 (88.5%) at 30 to 39 years, and 50 of 55 (90.9%) at 40 or more years.
  • Among the 185 men whose shipyard employment had been confined to this ship repair yard, the proportions with the various x-ray abnormalities were almost identical to those of the whole group.
  • Among all 284 workers with analyzable x-rays, a history of cigarette smoking made no appreciable difference in the prevalence of x-ray abnormalities. Normal films were found in 17.3% of 110 current smokers, 9.3% of 118 ex-smokers, and 16.1% of workers who had never smoked cigarettes.
  • Only 11.0% of examined workers had crepitant rales (crackling lung sounds), compared with 86.3% who had abnormal films.
  • Small rounded opacities were more common among welders and burners (10.3%) than among men in other trades (4.0%). The prevalence of all small opacities was virtually identical between the two groups.
  • Of 81 men whose x-rays in this examination were abnormal and who knew the result of an x-ray taken in the previous two years, 57 (printed as 70.0%) were unaware of any abnormality.
  • Five cases of previously undiagnosed lung cancer were found during the examinations. The article states these were to be reported separately.
• The authors' conclusion: The authors concluded that workers employed in ship repair, refitting, and maintenance had a significant risk of asbestosis. They added that repair of vessels built with asbestos could be extraordinarily hazardous unless industrial hygiene precautions were taken.
• Limitations the authors state:
  • Age and time since first exposure were strongly correlated, and abnormalities were very common overall, so the authors could not do a multivariate analysis to separate any effect of age.
  • Dust exposures outside shipyard work may have contributed to the x-ray abnormalities. The authors judged that they did not change the main findings.
  • Some of the abnormalities workers were unaware of may have developed after their earlier x-rays, though the authors considered this unlikely in many cases.

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: Asbestos Exposure, Lung Cancer, Industrial Hygiene, Shipyard Exposure.

Related studies

• Prevalence of chronic respiratory disease. Asbestosis in ship repair workers — B.G. Ferris, M.V. Panadive, et al. (1971)
• Asbestos-related disease in Bangladeshi ship breakers: a pilot study — M.N. Courtice, P.A. Demers, et al. (2011)
• Asbestotic radiological abnormalities among United States merchant marine seamen — I.J. Selikoff, R. Lilis, et al. (1990)
• Parenchymal asbestosis due to primary asbestos exposure among ship-breaking workers: report of the first cases from Bangladesh — V. Muralidhar, M.F. Ahasan, et al. (2017)
• Lung cancer prevalence among shipyard workers — W.J. Nicholson, R. Lilis, et al. (1980)
• Assessment of the future mesothelioma disease burden from past exposure to asbestos in ship recycling yards in India — R. Singh, J.W. Cherrie, et al. (2020)

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