Lung Function

Our plain-English summary of Lung Function, by M.R. Becklake (1973).

The study

• Author: M.R. Becklake
• Published: Biological Effects Of Asbestos (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 8, Pp. 31-39 (1973)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 002379. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1973 symposium chapter was a review. The author assessed how lung function had been measured in published studies of asbestos-exposed people, and grouped the methods by purpose. In four studies comparing exposed workers with non-exposed groups, the prevalence of chest X-ray changes in the exposed ranged from 28.5 to 43.6 percent. All four pointed to a lung volume test and a gas exchange test as the measures most likely to tell exposed from unexposed people. In three of four dust-dose studies, a dose relationship was found for vital capacity or inspiratory capacity but not for gas exchange tests. Work by the author's own group on Quebec chrysotile mine and mill workers related dust dose to breathlessness on exercise and to inspiratory capacity, but not to the overall pattern of exercise adaptation. A cited review of 305 published asbestosis case reports found a variety of lung function patterns, including airway-type (obstructive) patterns. The author concluded that vital capacity, inspiratory capacity or forced vital capacity appeared most satisfactory for health surveillance. The author noted that whether obstructive patterns are more common in exposed people remained to be determined.

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: Review of published lung function studies and methods, written for a symposium
• Who was studied: Published studies of asbestos-exposed populations, including insulators, pipe coverers, shipyard and dockyard workers, and Quebec chrysotile mine and mill workers. It also drew on a cited analysis of 305 published case reports of asbestosis.
• Exposure: Asbestos dust exposure in various industries. Dose was measured in the reviewed studies by years of service, job rating, or a risk index built from dust levels and duration. The reviewed studies included chrysotile mining and milling in Quebec.
• Main results:
  • In four studies comparing exposed with non-exposed groups, the prevalence of chest radiograph changes in exposed individuals ranged from 28.5 to 43.6 percent. The percent sign is damaged in the text. It is confirmed by Table 1's column heading, '% with chest X-ray'.
  • All four of these comparison studies concluded that a lung volume measurement (vital capacity or residual volume) and a gas exchange measurement were most likely to distinguish exposed from non-exposed people.
  • In three of four dust-dose studies, the authors concluded that a dust-dose relationship was demonstrable for vital capacity or inspiratory capacity, but not for gas exchange tests.
  • In one cited study (Bader et al., 1970), in the earlier years of exposure, lung function changes occurred in 32% and radiographic changes (Grade 2-3) in less than 5%. The author cautioned that the result might differ if Grade 1 changes were counted.
  • In the author's group's earlier data, changes in diffusing capacity occurred only when X-rays showed diffuse interstitial disease of moderate degree.
  • In a cited study of 25 workers with normal chest X-rays (Jodoin et al., 1971), those with heavier dust exposure had increased upstream resistance and static compliance. These changes are compatible with dust deposition around small airways.
  • In the Quebec chrysotile mine and mill worker data, dust dose was related to breathlessness on exercise and to inspiratory capacity, but not to the overall profile of exercise adaptation.
  • A cited review of 305 case reports found that asbestosis was associated with a variety of lung function profiles, including tests thought to depend on the airways.
• The authors' conclusion: The author concluded that the choice of test depends on purpose. To define whether a hazard exists, vital capacity or inspiratory capacity should be measured, alone or with residual volume and diffusing capacity. For health surveillance, vital capacity, inspiratory capacity or forced vital capacity appeared most satisfactory. To judge effects on overall function, detailed exercise testing is needed.
• Limitations the authors state:
  • Results of the comparison studies depend crucially on how subjects were selected.
  • Whether the obstructive profile is more common in asbestos-exposed than unexposed people, after accounting for smoking and other factors, remained to be determined.

Topics

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Quebec Chrysotile, Obstructive Lung Disease.

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