Asbestos-related disease among sheet-metal workers. Preliminary results of the National Sheet Metal Worker Asbestos Disease Screening Program

Our plain-English summary of Asbestos-related disease among sheet-metal workers. Preliminary results of the National Sheet Metal Worker Asbestos Disease Screening Program, by L.S. Welch, D. Michaels, S. Zoloth (Annals of the New York Academy of Sciences, 1991).

The study

• Authors: L.S. Welch, D. Michaels, S. Zoloth
• Journal: Annals of the New York Academy of Sciences
• Published: 1991;643:287-95
• Cited by: 6 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. 004937).

Summary of the article

The authors reported preliminary results of a national screening program for asbestos-related disease among sheet-metal workers. Members first employed in the construction sector at least 20 years earlier were invited for a questionnaire, physical examination, spirometry and chest X-ray read using the ILO classification, at 61 clinics in the United States and Canada. Of 26,329 invited, 12,454 (47%) had been examined. This analysis covered 8,288 male United States workers employed only in the building trades. Parenchymal disease was defined as ILO profusion 1/0 or greater. The proportion with pleural changes, parenchymal changes or both rose with years since first exposure, except in the shortest-latency group. Fewer than 1% had profusion 2/1 or higher. Ever-smokers had more parenchymal disease than never-smokers at every latency, and the difference for pleural disease was much smaller. Restrictive lung function was found in 10% and obstructive in 17% (17.6% of smokers, 3% of nonsmokers). Chronic bronchitis affected 22.8% of smokers and 11.7% of nonsmokers. Among men with 20-24 years since first exposure, 13% had pleural and 6% parenchymal disease, rates comparable to the 25-29 year group. The authors concluded that asbestos-related disease was common among sheet-metal workers, although they do not use asbestos directly. They suggested that asbestos already in place in buildings may also be causing disease.

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In plain English

This paper gave preliminary results from a medical screening survey of sheet-metal workers. Workers first employed in construction sheet-metal work at least 20 years earlier were invited, and 12,454 of 26,329 invited (47%) had been examined. The analysis covered 8,288 male United States workers employed only in the building trades. The authors explained that sheet-metal workers did not use asbestos themselves but were exposed near asbestos workers, in areas sprayed with asbestos fireproofing, and when renovating asbestos-insulated ventilation systems. Chest X-ray changes of the pleura, of the lung tissue (parenchyma), and of both rose with years since first exposure, except in the shortest-latency group. Fewer than 1% were classified 2/1 or higher. Among men 20-24 years from first exposure, 13% had pleural disease and 6% parenchymal disease. Ever-smokers had more parenchymal disease than never-smokers at each latency category, with a much smaller difference for pleural disease. Obstructive lung disease was found in 17.6% of smokers and 3% of nonsmokers. The authors concluded there was a high rate of asbestos-related disease among these 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 medical screening survey (preliminary results) using a questionnaire, physical examination, spirometry and chest X-rays read by the ILO classification
• Who was studied: Sheet-metal workers and contractors first employed in construction sheet-metal work at least 20 years earlier. 12,454 of 26,329 invited were examined at 61 clinics in the United States (56) and Canada (5), with 129 union locals taking part. The analysis covered 8,288 male United States workers employed only in the building trades. Those in railroad or shipyard work, those with incomplete or outlying data, and the 16 women were excluded. Data were as of June 1990.
• Exposure: Indirect asbestos exposure in construction (fiber type not specified): working near asbestos workers, in areas sprayed with asbestos fireproofing, on fireproofed beams, and retrofitting asbestos-insulated ventilation systems. The authors also mention fiberglass and welding fumes. Latency (years since first exposure) was the main analysis variable.
• Main results:
  • Participation rate was 47% overall (12,454 examined of 26,329 invited).
  • The proportion with pleural-only, parenchymal-only, and combined X-ray changes increased with years since first exposure, except in the group with the shortest latency.
  • Parenchymal X-ray changes were mainly in ILO major category 1. Fewer than 1% of participants were classified 2/1 or higher.
  • In the group with 20-24 years since first exposure, 13% had pleural disease and 6% had parenchymal disease. The authors described these rates as comparable to those of men with 25-29 years since first exposure.
  • Ever-smokers had higher rates of parenchymal disease than never-smokers at every latency category.
  • Smokers also appeared to have more pleural disease, but the difference was much smaller than for parenchymal disease.
  • Of all participants, 10% had restrictive and 17% had obstructive lung disease. Restrictive disease was found in 10.6% of smokers and 9.8% of nonsmokers.
  • Obstructive lung disease was found in 17.6% of smokers and 3% of nonsmokers.
  • Chronic bronchitis was present in 22.8% of smokers and 11.7% of nonsmokers. The authors said the nonsmoker rate was higher than expected from general population data.
• The authors' conclusion: The authors concluded that sheet-metal workers had a high rate of asbestos-related disease even though they do not use asbestos directly, and that such disease should be expected in all construction workers. They wrote that trends in these data suggest recent exposure, to asbestos already in place in buildings, may also be responsible, and that further examinations will show whether this is true.
• Limitations the authors state:
  • The authors could not separate the effects of exposure during spray application from exposure during renovation and maintenance of asbestos already in place.
  • Disabled workers may have been less likely to take part, which the authors said would tend to underestimate disease prevalence.
  • The authors noted that differences in exposure histories, participation rates and X-ray readings may explain why prevalence varies among building-trade surveys.

Topics

Medical terms in this study, explained in our Lexicon: Spirometry, Chest X-Ray, ILO Classification, Latency, Restrictive Lung Disease.

Related studies

• The National Sheet Metal Worker Asbestos Disease Screening Program: radiologic findings. National Sheet Metal Examination Group — L.S. Welch, D. Michaels, et al. (1994)
• Mortality among sheet metal workers participating in a respiratory screening program — L. Welch, J. Dement, et al. (2015)
• Change in prevalence of asbestos-related disease among sheet metal workers 1986 to 2004 — L.S. Welch, E. Haile, et al. (2007)
• Asbestos-related disease among sheet metal workers 1986-2004: radiographic changes over time — L.S. Welch, E. Haile (2009)
• Asbestos disease in sheet metal workers: proportional mortality update — D. Michaels, S. Zoloth (1988)
• Change in prevalence of asbestos-related disease among sheet metal workers 1986 to 2016 — G.H. West, R.K. Sokas, et al. (2019)

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