Pulmonary Disability In Asbestos Workers

Our plain-English summary of Pulmonary Disability In Asbestos Workers, by K.W. Smith (1955).

The study

• Author: K.W. Smith
• Published: Archives Of Industrial Health 12(2):198-203, August (1955)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 001878. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1955 article described lung disease among several thousand asbestos workers in Canada and the United States and reported two surveys. In an x-ray survey of 708 employees of an asbestos mill, 649 (91%) had normal chest x-rays, 52 showed markedly increased lung markings without definite asbestosis, and 7 had definite asbestosis. Those 7 were all working at their usual jobs with no signs of disability, and none had less than 20 years of exposure. Because workers rotated between jobs, the author could not link x-ray changes to particular jobs or dust levels. A second survey reviewed three years of sickness insurance claims among 1561 workers, roughly half of them in dusty jobs. Of the claims for respiratory illness, 45% came from dust-exposed workers. The author reported that illness rates and lengths of illness were about the same in both groups. The author concluded that very few exposed workers develop asbestosis. The author also wrote that conflicting reports made a causal link between asbestosis and lung cancer extremely difficult to confirm or deny.

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: Descriptive report by a company physician, including a chest x-ray survey of mill employees and a three-year review of sickness insurance claims comparing dusty and non-dusty jobs
• Who was studied: Several thousand men and women employed in the asbestos industry in Canada and the United States. The surveys covered 708 employees of one asbestos mill (x-rays) and a separate group of 1561 men and women in the asbestos industry (insurance claims).
• Exposure: Asbestos dust in a mill where ore was dried, crushed, separated, graded and packed. Employees rotated through jobs, so exposure to varying dust concentrations was assumed but not measured by job. In the claims survey, the comparison was between dusty and non-dusty occupations. Fiber type for the surveyed groups was not stated.
• Main results:
  • Of the 708 mill employees, 649 (91%) had normal x-rays
  • Of the 708 mill employees, 204 (29%) had 10 or more years of service, and 2 had worked more than 40 years
  • Of the 708 mill employees, 52 showed a marked increase of lung markings (P-2) but none had definite asbestosis
  • Of the 708 mill employees, 7 had definite x-ray evidence of asbestosis
  • All 7 men with asbestosis were working at their usual jobs with no signs of disability
  • None of the mill employees had x-ray evidence of asbestosis with less than 20 years of exposure
  • Among 1561 employees in the claims survey, 45% of claims for nonoccupational respiratory disease were for employees with dust exposure
  • Among the 1561 employees, the author reported that the rate of nonoccupational respiratory disease over the three years was about the same in the dusty and non-dusty groups, with no appreciable difference in duration of illness
  • In discussion, the author wrote that conflicting reports made a causal relationship between asbestosis and lung cancer extremely difficult to confirm or deny. The author noted differences among fiber types.
• The authors' conclusion: The author concluded that very few workers exposed to asbestos fibers develop asbestosis
• Limitations the authors state:
  • Because employees rotated through jobs, x-ray changes could not be related to a particular job or dust concentration
  • The x-ray survey covered only mill employees; the author noted that other operations might have different exposures and disease experience
  • Absentee records were judged unreliable because employees gave their own reasons for absence, so insurance claims were used instead

Topics

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Lung Cancer.

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