Asbestosis

Our plain-English summary of Asbestosis, by A.J. Lanza (1936).

The study

• Author: A.J. Lanza
• Published: Journal Of The American Medical Association 106(5):368-369, February 1 (1936)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 002962. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1936 paper, read before an American Medical Association section in 1935 by an assistant medical director of the Metropolitan Life Insurance Company, described asbestosis, a lung disease caused by inhaling asbestos dust, and compared it with silicosis. A search of company death records found asbestosis listed as a cause or contributing cause of death in only nineteen cases, six supported by autopsy. All nineteen were males. From the author's group's studies of asbestos mines and fabricating plants, the author reported 126 examinations of randomly selected workers exposed more than three years. Sixty-three had X-rays the investigators thought showed pneumoconiosis but indefinite symptoms; four had evident lung symptoms with corroborating X-rays. For patients without complicating infection, the author found the clinical picture milder than silicosis, though marked asbestosis could greatly resemble it; X-ray shadows were finer, giving a ground-glass impression. The author said seven death certificates citing asbestosis complicated by heart disease, none with autopsies, deserved limited weight, and noted that no comparative dust counts with England were available. The author concluded that, with dust being controlled, further disabling cases would probably be rare, but that much more study was needed.

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: Narrative paper read at a medical meeting. It combines an overview of the literature with the author's own death-record search and a summary of clinical examinations from the author's group's earlier studies.
• Who was studied: (1) Nineteen death records on file at the Metropolitan Life Insurance Company that listed asbestosis as a cause or contributing cause of death. All nineteen were males and all but one were white. (2) 126 asbestos workers in asbestos mines and fabricating plants, each with more than three years' exposure, selected at random for physical examination.
• Exposure: Inhalation of asbestos dust in asbestos mines and fabricating plants. The article describes Canadian asbestos as a hydrated magnesium silicate. Years of exposure were reported for workers with X-ray findings (more than ten and more than fifteen years).
• Main results:
  • In the company's death records, asbestosis was given as a cause or contributing cause of death in only nineteen cases: the first in 1924, two in 1927, one in 1931, and the rest since 1933.
  • Of the nineteen deaths, the diagnosis was supported by autopsy in only six. Among those six, the primary cause of death was carcinoma in one, glioma of the brain in another and pulmonary tuberculosis in another. In the other three, asbestosis was given as the primary cause with cardiac failure as the contributing cause.
  • Of 126 workers examined, sixty-three had an X-ray appearance the investigators thought indicated a pneumoconiosis, but with indefinite and inconclusive symptoms; these were called first stage. Four with evident lung symptoms and corroborating X-rays were called second stage. Of these sixty-seven, twenty had been exposed more than ten years and thirteen more than fifteen years.
  • The author found the clinical picture of asbestosis milder than that of silicosis, while noting that an individual patient with marked asbestosis will greatly resemble one with silicosis. Patients with asbestosis were apt to have clubbed fingers and to look pasty-faced, sometimes with slight cyanosis (bluish skin). The author said these descriptions referred to patients whose disease was not complicated by infection.
  • All the asbestosis patients detected were, with one exception, working steadily at their trades. Active tuberculosis was found in only one case, and that diagnosis was based only on the X-ray.
  • X-ray shadows in asbestosis were finer, more granular and softer than in silicosis, with a ground-glass impression and no nodules. They occupied the lower third of the lung except in far-advanced cases. A number of films showed enlarged hearts.
• The authors' conclusion: The author concluded that, because energetic steps had been taken to control dust in asbestos plants, further cases of disabling asbestosis would probably be rare. The author also concluded that much work remained before asbestosis could be spoken of as authoritatively as silicosis, including whether it progresses after exposure stops.
• Limitations the authors state:
  • The seven death certificates listing asbestosis complicated by heart disease had no autopsies, and the attending physician had diagnosed pulmonary tuberculosis in several of them. The author said too much weight could not be given to these certificates.
  • The author said the investigators were handicapped, especially at first, by evaluating asbestosis by the standards used for silicosis. Interpreting the X-rays and matching them to clinical evidence was difficult.
  • No comparative dust counts were available to support the impression that English factories might be dustier than American ones.
  • The X-ray appearance of asbestosis may not be distinctive of this disease alone, and more study of films from workers exposed to other dusts was needed.

Topics

Medical terms in this study, explained in our Lexicon: Silicosis, Autopsy, Pneumoconiosis, Death Certificate.

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