Relationship of lung geometry to the development of pleural abnormalities in insulation workers exposed to asbestos

Our plain-English summary of Relationship of lung geometry to the development of pleural abnormalities in insulation workers exposed to asbestos, by R. Delfino, P. Ernst, J. Bourbeau (American Journal of Industrial Medicine, 1989).

The study

• Authors: R. Delfino, P. Ernst, J. Bourbeau
• Journal: American Journal of Industrial Medicine
• Published: 1989;15(4):417-25
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000070).

Abstract

The relationship of respiratory airway and airspace geometry to radiographic evidence of pleural abnormality consistent with asbestos exposure was studied in 178 construction insulators. Lung geometry was assessed from tracings of radiographic shadows, and the measures taken were tracheal length and diameter, subcarinal angle, right and left lung lengths, and upper, middle, and lower lung widths. Important modifying variables--age, height, weight, exposure estimates, and smoking history--were included in a logistic regression model to test the significance of the lung geometry measurements as predictors of the presence or absence of pleural abnormality. No such relationships were found. Neither were there any differences in prevalence or severity of pleural disease between the right and left sides which might have been found if airway geometry were a significant determinant of asbestos pleural disease. These results do not support the hypothesis that lung geometry is a host risk factor for the development of asbestos-related pleural disease.

In plain English

This study asked whether the size and shape of the lungs and airways, measured on chest X-rays, were linked to pleural changes in asbestos-exposed construction insulation workers. It included 178 working insulators aged 20 to 50 near Montreal, studied in 1984. No dust measurements existed, so hours worked in the trade served as the exposure estimate. Of the 178, 77 had pleural change on X-ray and 101 did not. On average, those with pleural change were older and shorter, had worked longer, and had slightly lower forced vital capacity. After adjusting for age, height, weight, smoking and exposure, no airway or lung measurement differed significantly between the groups. A slightly smaller mid-lung width in the pleural-change group disappeared once lung capacity was accounted for. Pleural scores did not differ significantly between the right and left sides. The authors concluded that the results did not support lung geometry as an important risk factor for pleural change, mainly pleural plaques. They noted that they used current rather than pre-employment X-rays, and that probable misreading of pleural disease reduced statistical power.

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: Comparison of lung and airway measurements traced from current chest X-rays in workers with and without pleural change, using logistic regression to adjust for other factors
• Who was studied: 178 construction insulators (union local 58), aged 20-50, currently working and living within 25 km of Montreal; data collected in 1984. 77 had pleural change and 101 did not.
• Exposure: Asbestos exposure in the insulation trade, estimated from the number of hours worked in the trade. No dust measurements were available. Fiber types are not named.
• Main results:
  • Without adjustment, subjects with pleural change were on average shorter, had worked more years and hours, were older, and had slightly smaller forced vital capacity (percent predicted) than those without.
  • Without adjustment, airway measurements (subcarinal angle, tracheal length and diameter) were very similar in the two groups.
  • After adjustment for age, height, Quetelet index, pack-years, years since first employment and hours of work, no airway or airspace measurement differed significantly between subjects with and without pleural change.
  • Subjects with pleural change showed a trend toward smaller midlung width (p = .06), which disappeared when FVC percent predicted was added to the model. Without height in the model, midlung width differed at p = .04, and this was also related to FVC.
  • Among the 77 subjects with pleural change, mean pleural scores did not differ significantly between the right and left sides.
• The authors' conclusion: The authors concluded that the study does not support individual differences in lung and airway size and configuration as an important determinant of risk for pleural change. They said the results apply primarily to pleural plaques.
• Limitations the authors state:
  • Current rather than pre-employment X-rays were used, and existing pleural change might obscure differences in lung geometry present at the start of employment.
  • Probable misclassification of whether pleural disease was present reduced the power to detect differences.
  • Because of the small sample size and correlation among the variables, the model's effect-size estimates are unlikely to be correct.
  • No workplace dust measurements were available, so hours worked served as the exposure estimate.

Topics

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

Medical terms in this study, explained in our Lexicon: Insulator, Asbestos Exposure, Asbestos-Related Pleural Disease.

Related studies

• Symptomatic benign pleural effusions among asbestos insulation workers: residual radiographic abnormalities — R. Lilis, Y. Lerman, et al. (1988)
• Risk and significance of chest radiograph and pulmonary function abnormalities in an elderly cohort of former nuclear weapons workers — M.A. Mikulski, P.G. Hartley, et al. (2011)
• Diffusing capacity and forced vital capacity in 5,003 asbestos-exposed workers: relationships to interstitial fibrosis (ILO profusion score) and pleural thickening — A. Miller, R. Warshaw, et al. (2013)
• Inter-reader variability in chest radiography and HRCT for the early detection of asbestos-related lung and pleural abnormalities in a cohort of 636 asbestos-exposed subjects — E. Ochsmann, T. Carl, et al. (2010)
• The radiographic pleural abnormalities in asbestos exposure: relationship to physiologic abnormalities — R.N. Jones, T. McLoud, et al. (1988)
• Relationship between chest X-ray findings and pulmonary function tests in dust workers — Y. Tonori, M. Niitsuya, et al. (2005)

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