Asbestos disease in sheet metal workers: II. Radiologic signs of asbestosis among active workers

Our plain-English summary of Asbestos disease in sheet metal workers: II. Radiologic signs of asbestosis among active workers, by D. Michaels, S. Zoloth, M. Lacher, et al (American Journal of Industrial Medicine, 1987).

The study

• Authors: D. Michaels, S. Zoloth, M. Lacher, E. Holstein, R. Lilis, E. Drucker
• Journal: American Journal of Industrial Medicine
• Published: 1987;12(5):595-603
• Cited by: 14 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. 000338).

Abstract

A review of chest x-rays of 707 currently employed New York metropolitan area sheet metal workers found that 29.3% of the workers with 20 years or more of union membership (a surrogate for years of exposure) had radiologic abnormalities characteristic of parenchymal and/or pleural asbestosis, with 18.6% having abnormalities characteristic of parenchymal asbestosis (International Labor Organization [ILO] classification 1/0 or higher) and 17.4% of pleural asbestosis. The prevalence of abnormalities characteristic of either parenchymal and/or pleural asbestosis in the group as a whole was 16.4%, with 10.9% exhibiting signs of parenchymal asbestosis and 9.2% of pleural asbestosis. There was a strong, statistically significant relationship between years in the trade and the prevalence of radiologic abnormalities. These findings underscore the need for medical surveillance of all asbestos-exposed construction workers, including retirees and workers who have had past exposure but who are no longer exposed.

In plain English

This cross-sectional study reviewed chest x-rays of active New York-area members of Local 28 of the Sheet Metal Workers International Association who were screened between January 1982 and June 1983. Of 832 participants, the analysis covered 707 who had both an x-ray reading by one of two experienced physicians and union membership records. Because recorded work histories were not adequate, length of union membership was used as a stand-in for asbestos exposure. Overall, 116 of 707 workers (16.4%) had x-ray signs characteristic of lung-tissue (parenchymal) and/or pleural asbestosis. Measured against all 707 workers, 77 (10.9%) had parenchymal changes graded ILO 1/0 or higher and 65 (9.2%) had pleural abnormalities, 17 of them pleural plaques; some workers had both. Among the 311 longest-serving members, 29.3% had such signs, compared with 6.3% of those with less than 20 years. Prevalence rose significantly with years of membership. The authors concluded that sheet metal workers are at risk for asbestos-related disease. They judged that excluding retirees most probably underestimated disease in the trade. They also named voluntary participation and missing exposure histories as limitations.

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 study using existing medical records and chest x-rays from a union medical screening program
• Who was studied: Currently employed (active) members of Local 28 of the Sheet Metal Workers International Association, New York metropolitan area, examined January 1982 to June 1983. Of 832 participants, 767 had x-rays read, and 707 had both a valid x-ray reading and complete union membership records. Mean age was 40 and average union membership was 19 years. Retirees were not eligible.
• Exposure: Asbestos exposure as sheet metal workers; fiber type not specified. Length of union membership was used as a surrogate for years of exposure because recorded occupational histories were not adequate.
• Main results:
  • 77 of all 707 workers (11%, given as 10.9% in Table III) had x-ray evidence of interstitial (parenchymal) fibrosis with ILO profusion 1/0 or greater.
  • Among the 77 with parenchymal changes, 45 had profusion 1/0, 24 had 1/1, 4 had 1/2, and 4 had 2/2 or greater. This group had a mean age of 49 and an average of 26 years of membership.
  • In the group with parenchymal changes, half were current smokers and 88% had smoked at some time.
  • Parenchymal abnormalities increased significantly with years of membership (chi-square 36.3, p less than .001). Table III gives 4 of 186 (2.2%) for less than 10 years, 15 of 210 (7.1%) for 11 to 20 years, and 58 of 311 (18.6%) for more than 20 years.
  • 65 of all 707 workers (9%, given as 9.2% in Table IV) had x-ray signs typical of asbestos-related pleural abnormalities.
  • Of the 65 workers with pleural abnormalities, 17 had pleural plaques. Unilateral pleural thickening was the most common finding, seen in 67% of them.
  • Pleural abnormalities also increased significantly with years of membership. They were found in 17% (54 of 311 in Table IV) of the group with the most seniority and in 1% (2 of 186) of members with less than 10 years.
  • In the total population, 16% (116 of 707, given as 16.4% in Table V) had x-ray signs of pleural and/or parenchymal abnormalities.
  • 29.3% (91 of 311 in Table V) of workers with 20 or more years of union membership had pleural and/or parenchymal abnormalities, compared with 6.3% of those with less than 20 years.
  • Among workers with less than 11 years of membership, those with x-ray abnormalities had a mean age of 43, compared with 31 for those without. The authors suggested some of these cases may be partly due to asbestos exposure before joining the union.
• The authors' conclusion: The authors concluded that the data support the view that sheet metal workers, like other construction trades, are at risk for asbestos-related disease. They also stated that medical surveillance should include workers with past exposure and retirees.
• Limitations the authors state:
  • Only currently employed workers took part. Excluding retirees, who had many years of exposure, most probably led to an underestimate of the true prevalence of disease in the trade.
  • Participation was voluntary, and exposure or disease status may have influenced who took part.
  • Comprehensive exposure histories were not available.
  • Some workers worked only in fabrication and may not have been exposed to asbestos. Including them may have diluted the results and underestimated prevalence among exposed workers.
  • Years of union membership is closely tied to age. If age independently affects risk, the findings could be biased.
  • Differences between the two x-ray readers were not assessed.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

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

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)
• Exposure of sheet-metal workers to asbestos during the construction and renovation of commercial buildings in New York City. A case study in social medicine — E. Drucker, D. Nagin, et al. (1987)
• Change in prevalence of asbestos-related disease among sheet metal workers 1986 to 2016 — G.H. West, R.K. Sokas, et al. (2019)
• 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)
• Asbestos-related disease among sheet-metal workers. Preliminary results of the National Sheet Metal Worker Asbestos Disease Screening Program — L.S. Welch, D. Michaels, et al. (1991)

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