Asbestos-related diseases in construction carpenters

Our plain-English summary of Asbestos-related diseases in construction carpenters, by M. García-Closas, D.C. Christiani (American Journal of Industrial Medicine, 1995).

The study

• Authors: M. García-Closas, D.C. Christiani
• Journal: American Journal of Industrial Medicine
• Published: 1995;27(1):115-25
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To assess the association of minimal parenchymal fibrosis and pleural plaques with respiratory functional impairment, we conducted a survey of 631 asbestos-exposed construction carpenters. This population had a relatively low prevalence of radiographic abnormalities and lung function impairment. Pleural plaques was the asbestos-related disease most prevalent, followed by interstitial fibrosis with predominantly low profusion scores. The most frequent functional impairment was the obstructive pattern, followed by restrictive and mixed patterns. After adjusting for potential confounders, the presence of pleural plaques was significantly associated with a mixed respiratory pattern of impairment (OR = 3.7, 95% CI 1.4-12.3). Furthermore, our data were consistent with a weak association between pleural plaques and a predominantly restrictive defect (OR-1.3, 95% CI 0.4-3.9). This study also suggested an association between minimally detectable profusions and both obstructive (OR = 1.9, 95% CI 0.6-6.3) and mixed (OR = 1.6, 95% CI 0.3-7.1) defects. Although only 631 of a potential 7,649 active and retired union members participated in this first-time survey and were relatively young, these findings add new evidence to the functional importance of pleural fibrosis and minimal parenchymal fibrosis.

In plain English

This cross-sectional study surveyed 631 active and retired members of a carpenters' union in eastern Massachusetts in 1987 and 1988, out of 7,649 members offered the survey. The union's carpenters were exposed to asbestos products used mainly in insulation and fireproofing, and 97.5% of participants reported having worked with asbestos-containing products. All had breathing tests and chest X-rays. Most (457, 72.4%) had normal X-rays, and 106 (16.8%) showed pleural fibrosis, nearly all of it pleural plaques. After adjusting for factors including smoking and years in the trade, pleural plaques were associated with a mixed pattern of breathing impairment (odds ratio 3.76, 95% confidence interval 1.45 to 12.33). Associations between plaques and a restrictive pattern, and between the lowest X-ray scarring score (0/1) and obstructive or mixed patterns, were not statistically significant. The authors concluded that, in the carpenters who took part, pleural plaques were significantly associated with mixed impairment. They noted the low participation rate, a relatively young and mostly active group, small numbers with abnormal X-rays, and that X-rays can miss pleural plaques.

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 survey (questionnaire, spirometry and chest X-ray)
• Who was studied: 631 members (618 active, 13 retired) of the International Brotherhood of Carpenters and Joiners union (district/local 33) in eastern Massachusetts, out of 7,649 members offered the survey (3,897 active, 3,752 retired), 1987 to 1988. The group was 506 construction carpenters, 55 millwrights and 69 in other jobs such as welding, painting and ship repair. 624 participants were male and white.
• Exposure: Asbestos products used mainly in insulation and fireproofing on commercial construction sites. Some millwrights regularly worked on asbestos-covered steam lines. 97.5% of participants reported working with asbestos-containing products. No fiber types or doses were given.
• Main results:
  • Of all 631 participants, 457 (72.4%) had no X-ray abnormalities.
  • Pleural fibrosis was seen in 106 workers (16.8%): three had diffuse pleural fibrosis and the rest had pleural plaques. Interstitial markings consistent with fibrosis were seen in 43 (6.8%).
  • Breathing-test patterns among the 631: obstructive 15.2% (n = 96), restrictive 4.2% (n = 27), mixed 3.8% (n = 24). The mixed figure is printed as '3.896' in the text; Table II gives 3.8.
  • Pleural plaques were associated with a mixed pattern of impairment: OR = 3.7, 95% CI 1.4-12.3 (Table V: 3.76, 1.45 to 12.33). This was adjusted for years in trade, smoking habit, pack-years, occupation and interstitial fibrosis.
  • Pleural plaques and a restrictive defect showed a weak association that was not statistically significant (Table V: OR 1.27, 95% CI 0.41 to 3.94). For an obstructive defect, the OR was 1.03 (0.47 to 2.22).
  • In linear models, pleural plaques were associated with decreases in FEV1 (-121 ml, p = 0.11) and FVC (-129 ml, p = 0.13). These were not statistically significant.
  • When pleural plaques and diffuse pleural fibrosis were counted together, the association with a mixed defect was OR = 5.1, 95% CI 1.7-15.4. The decreases were FEV1 -145 ml (p = 0.04) and FVC -152 ml (p = 0.05).
  • Minimal parenchymal fibrosis (ILO score 0/1, n = 23) was not significantly associated with lung function defects (Table V: obstructive OR 1.96, 95% CI 0.60 to 6.36; mixed OR 1.60, 0.36 to 7.10). The authors described a trend toward increased risk. ORs were higher for profusion 1/0 or above (n = 20): obstructive 2.28 (0.69 to 7.54); mixed 2.70 (0.63 to 11.62).
  • Current smokers had an increased risk of an obstructive defect (OR = 2.8, 95% CI 1.0-7.6). For former smokers, the OR was 0.5 (95% CI 0.2-1.3).
  • Workers with interstitial fibrosis grade 2 (profusion 1/0 or higher) compared with those without it, for shortness of breath (dyspnea): OR = 2.9, 95% CI 0.81-10.27.
• The authors' conclusion: The authors concluded that, in the union carpenters who took part, asbestos-related pleural plaques were significantly associated with a mixed pattern of respiratory impairment. They also concluded that their data suggested an association between minimally detectable profusion of small opacities and reductions in lung volumes consistent with obstructive and mixed defects. They called for more research.
• Limitations the authors state:
  • Most participants were active and relatively young, so the prevalences found are probably underestimates for the whole union population.
  • Few workers had abnormal X-rays, which lowered the power to detect significant associations.
  • Because of low participation, sicker workers may have been more likely to enroll. The authors said they had no evidence this biased the associations.
  • X-ray readings vary between readers and can miss pleural plaques. The authors said this likely misclassified fibrosis and would tend to underestimate associations.
  • Only three workers had diffuse pleural thickening, so its separate effect could not be assessed.

Topics

Medical terms in this study, explained in our Lexicon: Parenchymal Fibrosis, Pleural Plaques, Interstitial Fibrosis, Obstructive Lung Disease, Fibrosis.

Related studies

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• Asbestos-related disease in railroad workers. A cross-sectional study — L.C. Oliver, E.A. Eisen, et al. (1985)
• Asbestos-related disease in public school custodians — L.C. Oliver, N.L. Sprince, et al. (1991)
• Spirometric impairments in long-term insulators. Relationships to duration of exposure, smoking, and radiographic abnormalities — A. Miller, R. Lilis, et al. (1994)
• Cases of alleged asbestos-related disease: a radiologic re-evaluation — R.B. Reger, W.S. Cole, et al. (1990)
• Asbestos-related diseases in automobile mechanics — J. Ameille, N. Rosenberg, et al. (2012)

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