Pulmonary Function Studies in Men Exposed for 10 or More Years to Inhalation of Asbestos Fibres

Our plain-English summary of Pulmonary Function Studies in Men Exposed for 10 or More Years to Inhalation of Asbestos Fibres, by G.W. Wright, F. Gregoire.

The study

• Authors: G.W. Wright, F. Gregoire
• Published: Department of Physiology
• Type of article: Report
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

Lung function was measured in 74 men. Fifty-seven had been exposed at work for many years to different concentrations of asbestos dust; the other 17 had no asbestos exposure beyond possible exposure in their community. Exposure was scored in units of duration times intensity, and chest X-rays were graded 0, P1, P2 or P2* (frank asbestosis). The authors found some but not good correlation between exposure and X-ray changes. Abnormal lung-function results matched the X-ray pattern better than they matched exposure. Among the exposed men, 23 had an abnormally increased alveolar-arterial oxygen difference during exercise, 22 a subnormal vital capacity, 12 a subnormal maximum oxygen uptake and 9 a subnormal maximum breathing capacity as a percentage of the predicted normal value. Absolute residual air showed no significant change except a slight reduction in the P2* group. Some men without frank asbestosis on X-ray had impaired oxygen transfer. The authors concluded that the abnormality was chiefly a "tight" lung, expanded with difficulty, with impaired gas transfer. The men were not a random sample of workers, and the study was not designed to show how common abnormalities are in the asbestos industry.

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 comparison of lung-function and exercise tests in exposed and unexposed men, with individual case examples
• Who was studied: 74 men: 57 exposed at work for many years to different concentrations of asbestos dust, and 17 with no exposure to asbestos fibre other than what might possibly occur to anyone living in their community. The place and dates of the workers are not stated.
• Exposure: Asbestos dust (fibre type not named), scored in units for duration multiplied by intensity of exposure, based on jobs such as bagger, chipper and mill work
• Main results:
  • There was some but not good correlation between duration and intensity of exposure and the X-ray pattern of asbestosis
  • Abnormal physiological findings correlated better with the X-ray pattern than with intensity and duration of exposure
  • In exposed men, lung size and vital capacity were restricted, but there was no relationship between the size of the change and the severity of exposure
  • Among the 57 exposed men, 23 had an abnormally increased alveolar-arterial oxygen difference during exercise
  • Among the 57 exposed men, 22 had a subnormal vital capacity
  • Among the 57 exposed men, 12 had a subnormal maximum ability for oxygen uptake during exercise
  • Among the 57 exposed men, 9 had a subnormal maximum breathing capacity as a percentage of the predicted normal value
  • Total lung volume was markedly reduced, especially in men with more severe X-ray changes
  • Residual air in absolute values showed no significant change except for a slight reduction (in the P2* group in Table XV). The increase in residual air as a percentage of total volume resulted from a drop in vital capacity alone.
  • Maximum breathing capacity was significantly low in X-ray categories P2 and P2*
  • Peak oxygen uptake fell significantly in the P2 and P2* groups, but most men in these two groups still retained normal capability for maximum oxygen uptake
  • The majority, but not all, of the men classed P2* (frank asbestosis) showed some abnormal impediment to oxygen transfer
  • Some men whose X-rays were not abnormal enough to be classed P2* also showed abnormal impediment to oxygen transfer. The authors suggested that the X-ray is not necessarily the earliest indicator of injury.
  • There was no true correlation between the blood-gas findings and the men's capacity to work on a treadmill
• The authors' conclusion: The authors concluded that the physiological abnormality was chiefly a "tight" lung that expands with difficulty, with impaired gas transfer. They contrasted this with the obstructive emphysema they described as most commonly seen in silicosis.
• Limitations the authors state:
  • The men studied did not include all exposed men in any one plant and were not a random sample of the working population. The authors chose them for the degree of exposure needed for the study.
  • The study was not designed to show what proportion of men working in the asbestos industry might have X-ray or physiological abnormalities

Topics

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

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