High-resolution computed tomography abnormalities in ex-insulators annually exposed to asbestos dust

Our plain-English summary of High-resolution computed tomography abnormalities in ex-insulators annually exposed to asbestos dust, by J.M. Soulat, D. Lauque, Y. Esquirol, et al (American Journal of Industrial Medicine, 1999).

The study

• Authors: J.M. Soulat, D. Lauque, Y. Esquirol, M. Déprés, J. Giron, R. Claudel, P. Carles
• Journal: American Journal of Industrial Medicine
• Published: 1999;36(6):593-601
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: characterize To the effects of high asbestos exposure during annual periods of insulation.

Method: 170 ex-workers underwent clinical examination, spirometry, standard chest X-rays and high-resolution computed tomography (HRCT). Asbestos exposure was retrospectively assessed for latency, duration, and intensity.

Results: Sixty-six percent of these workers were annually exposed to high concentrations of asbestos dust. Respiratory symptoms were mild. One hundred and nineteen subjects had pleural or pulmonary changes on HRCT, compatible with asbestos exposure. Localized pleural thickening was found in 113 subjects (66.5%); pulmonary nodules or lines in 35 (20.6%). The presence of pleural plaques was linked to intensity of asbestos exposure (P <.01), and length of employment (P <.05). Parenchymal lesions were related to intensity (P <.05) and duration of exposure (P <.05). Lung function of subjects with X-ray changes was not significantly altered.

Conclusions: Annual asbestos exposure led to a high prevalence of pleural plaques and to mild parenchymal anomalies.

Copyright 1999 Wiley-Liss, Inc.

In plain English

This cross-sectional study examined 170 retired workers from a nitrate fertilizer plant in Carmaux, southwestern France. Each year the plant shut down for two weeks while most workers removed bulk asbestos insulation from distillers, dried it outdoors and put it back. The type of asbestos was poorly identified, but lung washing fluid from one worker with pleural plaques showed chrysotile and crocidolite. Exposure was rated from work histories, and 112 workers (65.9%) were rated as highly exposed. Standard chest X-rays showed pleural thickening in 56 workers (32.9%). High-resolution CT scans showed pleural thickening, mostly localized plaques, in 113 (66.5%) and lung tissue (parenchymal) changes in 35 (20.6%). Both kinds of change were statistically related to the duration and intensity of exposure. Average breathing test results did not differ significantly between workers with and without CT abnormalities. The authors concluded that annual asbestos exposure led, after a long time, to a high prevalence of localized pleural plaques and to only mild parenchymal abnormalities without a significant decrease in lung function. They noted that no quantitative exposure measurements were available.

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 with clinical examination, spirometry, standard chest X-rays and high-resolution CT (HRCT)
• Who was studied: 170 retired ex-workers of a nitrate fertilizer plant in Carmaux, southwestern France (plant built 1945, closed 1971), drawn from 254 living potentially exposed ex-workers identified from a list of 350; mean age 65.2 years at the time of study
• Exposure: Bulk asbestos insulation of distillers, handled during an annual two-week shutdown: asbestos was extracted, dried outdoors and reinstalled. Fiber type was poorly identified, and bronchoalveolar lavage fluid from one patient showed chrysotile and crocidolite. Exposure was rated on a semi-quantitative index: high in 112 (65.9%), moderate in 21 (12.3%), low in 21 (12.3%), not exposed in 10 (5.9%), undetermined in 6 (3.5%). 53 had also worked in coal mines.
• Main results:
  • On standard chest X-rays, 56 of 170 subjects (32.9%) had pleural thickening; only one of them had diffuse bilateral pleural thickening, and the others had localized pleural plaques.
  • On standard chest X-rays, abnormal lung densities rated 1/0 or higher on the ILO profusion scale were found in only nine ex-workers (5.3%).
  • HRCT showed pleural thickening in 113 subjects (66.5%): bilateral in 77 and unilateral in 36. Plaques were calcified in 81 of these 113 (71.7%).
  • HRCT showed parenchymal changes in 35 subjects (20.6%). All were subpleural and located in the postero-basal part of the lung. Six of these subjects had parenchymal lesions without pleural fibrosis.
  • Pleural thickening was related to duration (P less than .05) and intensity (P less than .01) of asbestos exposure in univariate and multivariate analyses.
  • Parenchymal abnormalities were related to duration (P less than .01) and intensity (P less than .05) of exposure. The results did not change when age, heart disease history and tobacco use were included in the analysis.
  • Mean spirometry values did not differ significantly between subjects with and without pleural thickening or parenchymal densities on HRCT (167 subjects had spirometry).
  • Crackles were heard in 35 subjects (20.6%) and were more frequent in those with HRCT abnormalities. In multivariate analysis, however, crackles were related to age and cardiac history.
• The authors' conclusion: The authors concluded that previous annual asbestos exposure in these insulation workers led, after a long period, to a high prevalence of localized pleural plaques, and to mild parenchymal abnormalities without a significant decrease in lung function.
• Limitations the authors state:
  • All plant archives disappeared when the factory closed in 1971, so exposure was assessed retrospectively from interviews.
  • No quantitative exposure measurements were available; the authors assumed exposure intensity was homogeneous within each exposure category.

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, Spirometry, Chest X-Ray, High-Resolution CT (HRCT), Latency, Pleural Thickening, Pleural Plaques.

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