A Memorandum On Asbestosis

Our plain-English summary of A Memorandum On Asbestosis, by E.R.A. Merewether (1933).

The study

• Author: E.R.A. Merewether
• Published: Tubercle 15:69-81, November And 15:109-118, December (1933)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 003048. The article is still under copyright, so we describe it here rather than post it.

In plain English

This article was a review by the author, one of H.M. Medical Inspectors of Factories in Great Britain. The text supplied is only its first installment (November 1933); the December part was missing. The author reviewed the industry's growth, the history and delayed recognition of asbestosis, its features and diagnosis, and the 'asbestosis bodies' found in workers' lungs. The author stated that its data came mainly from an earlier British inquiry begun in 1928, which clinically examined 363 workers and X-rayed 133, and from the first statutory medical examinations. The author described asbestosis as scarring of the lungs caused by breathing asbestos dust. Between 50 and 60 percent of cases complained of cough and breathlessness on exertion. The author wrote that the disease could not be diagnosed with absolute certainty by physical or X-ray examination alone. Single asbestosis bodies in sputum were said only to indicate exposure. Clumps like those in scarred lungs pointed to breakdown of lung tissue, and other researchers suggested these meant definite underlying asbestosis. The author considered the existing evidence amply sufficient to justify compensation and control regulations.

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 (memorandum) of existing knowledge on asbestosis, drawing mainly on an earlier British inquiry and on statutory medical examinations
• Who was studied: No new study population. The memorandum drew on an earlier inquiry in Great Britain, begun in February 1928, that clinically examined 363 asbestos workers (about 16.5 per cent of the estimated population at risk), 133 of them by X-ray. It also drew on the first cycle of statutory periodic medical examinations in the asbestos industry.
• Exposure: Inhalation of asbestos dust in asbestos quarrying and manufacturing. The article described the commercial forms as chrysotile (fibrous serpentine) and hornblende-group minerals, including crocidolite and amosite. It also mentioned workers exposed to the insulating material 'magnesia asbestos'.
• Main results:
  • The author estimated that between 2,000 and 3,000 workers in Great Britain were exposed to the risk in manufacturing processes
  • Among cases of asbestosis, between 50 and 60 percent complained of cough and of undue shortness of breath on exertion
  • The author wrote that asbestosis could not be diagnosed with absolute certainty on physical examination or X-ray examination alone. With both together, the disease could be diagnosed with certainty if present in some degree.
  • The author described the X-ray appearances of developed or advanced asbestosis as distinctive but not specific
  • The author wrote that death was usually brought about by an acute infection. The author stated there was no evidence that developed asbestosis made workers more likely to get such infections, but that it seriously impaired the chance of recovery if one occurred.
  • The author wrote that the presence of asbestosis bodies in the sputum could only be taken as indicating exposure to asbestos dust
  • The author wrote that bodies found in clumps in the sputum, rather than individually, matched the clumps seen in fibrosed lungs and pointed to disintegration of lung tissue. The author cited a suggestion by Stewart, Tattersall and Haddow that in such cases it was reasonable to conclude there was a definite underlying asbestosis.
  • The author attributed the delayed recognition of asbestosis partly to the focus on free silica, which tended to obscure the possibility that other dusts could be harmful
• The authors' conclusion: The author concluded that the evidence already available was amply sufficient to show that asbestosis should be made a compensatable industrial disease. The author also concluded that regulations were needed to control the disease and ultimately abolish it.
• Limitations the authors state:
  • The author stated there were no precise data for estimating the number of workers exposed worldwide (estimated at 35,000 to 40,000)
  • The author stated that no autopsy findings were available for workers exposed to magnesia asbestos, so the underlying lung lesion could not be determined
  • The author stated that no attempt was made to compile a complete bibliography

Topics

Medical terms in this study, explained in our Lexicon: Sputum.

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