Asbestos As An Urban Air Contaminant

Our plain-English summary of Asbestos As An Urban Air Contaminant, by J.G. Thomson, R.C. Path, W.M. Graves, et al (1966).

The study

• Authors: J.G. Thomson, R.C. Path, W.M. Graves, Jr
• Published: Archives Of Pathology 81:458-464, May (1966)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 004717. The article is still under copyright, so we describe it here rather than post it.

In plain English

This Miami autopsy study copied a Cape Town survey's method. The authors examined smears from the lung bases in 500 consecutive autopsies of people 15 and over at Jackson Memorial Hospital (304 males, 196 females). They counted asbestos bodies (fibers coated with protein and iron). Asbestos bodies were found in 31.6% of males and 20.4% of females, mostly scanty or very scanty. In 18 cases, all males, bodies were numerous, which the authors thought probably reflected work exposure. The one man with very frequent bodies, a mining engineer, had classical asbestosis and died of bronchial carcinoma. For the other 17, occupational details were lacking; no significant pulmonary asbestosis was seen at autopsy, though without lung-base sections limited or minimal basal asbestosis could not be diagnosed or excluded. The authors concluded that the scanty bodies likely reflected asbestos in city air and were of no present significance as a cause of lung fibrosis or disability. They forecast a rise in mesothelioma of the pleura and peritoneum. They noted that smears missed bare fibers and that some subjects were not city dwellers.

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: Autopsy series (examination of lung-base smears for asbestos bodies), planned to compare with an earlier Cape Town series using the same technique
• Who was studied: 500 consecutive autopsies of subjects aged 15 years and over at Jackson Memorial Hospital, Miami, Florida: 304 males and 196 females, about one quarter Negro
• Exposure: General urban (non-occupational) inhalation of asbestos, judged by asbestos bodies in smears from the lung bases. Asbestos bodies were used as a marker of asbestos inhalation. Fiber types in the lungs were not identified.
• Main results:
  • Asbestos bodies were found in the lung bases of 31.6% of the males and 20.4% of the females; the table gives 136 positive cases of 500 examined.
  • Frequency rose with age in both sexes. In males the peak was 36.5% positive in the 45-54 age group, falling to 29.4% in those aged 75 and over.
  • Negro subjects had approximately 10% more positive cases than Caucasian subjects.
  • In 18 cases, all males (about 1 in 17 of the males), asbestos bodies were numerous. The authors stated this was identical to the Cape Town males.
  • The one case with very frequent asbestos bodies was a mining engineer who died from bronchial carcinoma and had classical asbestosis.
  • In the 17 other males with frequent asbestos bodies, no significant pulmonary asbestosis was evident at autopsy, though lung-base sections were not available to diagnose or exclude limited or minimal basal asbestosis. None had pulmonary disability, and all died from other causes.
  • Of the 40 positive females, 37 had very scanty asbestos bodies and 3 had scanty bodies; none had frequent bodies.
• The authors' conclusion: The authors concluded that the cases with numerous bodies were likely occupational. They regarded the scanty bodies as of no present significance as a cause of pulmonary fibrosis or disability, and attributed them to contamination of city air. They forecast an increase in malignant mesothelioma of the pleura and peritoneum rather than in pulmonary disease or disability.
• Limitations the authors state:
  • Not all subjects were urban dwellers; some came from outlying villages and country areas.
  • The method is subject to error from the amount of fluid, blood or exudate in the lung bases.
  • The smear method cannot detect bare asbestos fibers, only fibers converted into asbestos bodies. The findings do not show the full extent of asbestos dust inhalation.
  • The counts apply only to the bases of the lungs, not to the lungs as a whole.
  • No occupational details were available for the 17 other males with frequent asbestos bodies.
  • Lung-base tissue sections were not available, so limited or minimal basal asbestosis could not be diagnosed or excluded.
  • No older figures exist to show whether this is a new development.

Topics

Medical terms in this study, explained in our Lexicon: Autopsy, Asbestos Bodies, Carcinoma, Asbestosis, Fibrosis, Mesothelioma, Pleura, Peritoneum.

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