The incidence of asbestos bodies in the lungs at random necropsies in Montreal

Our plain-English summary of The incidence of asbestos bodies in the lungs at random necropsies in Montreal, by L. Anjilvel, W.M. Thurlbeck (Canadian Medical Association Journal, 1966).

The study

• Authors: L. Anjilvel, W.M. Thurlbeck
• Journal: Canadian Medical Association Journal
• Published: 1966;95(23):1179-82
• Cited by: 53 articles, as counted by NIH iCite
• Read it: PubMed · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004320).

Abstract

The incidence of asbestos bodies in the lungs of adult patients selected at random, who died in four Montreal hospitals, was studied by examining fresh unstained smears of lungs obtained at necropsy. Two techniques were used for preparation of the smears and an arbitrary grading system was developed to estimate the degree of contamination of the lungs by asbestos bodies.Asbestos bodies were present in 48 out of 100 necropsies; they were found in 32 of 56 men (57%) and in 16 of 44 women (34%). Men were more heavily contaminated. The proportion of positive smears depended on the technique used and the amount of lung sampled. No particular association was noted between asbestos bodies in the lungs and the presence of cancer in the 33 patients in this series with malignant disease. The high incidence in this random series suggests that asbestos is a significant air contaminant in Montreal.

In plain English

This study looked for asbestos bodies in the lungs of 100 adults chosen at random from necropsies (autopsies) at four Montreal hospitals. The authors examined fresh, unstained lung smears and identified asbestos bodies by their appearance under the microscope. The type of asbestos fiber was not determined. Using a 'scraping' method on the left lung, they found asbestos bodies in 48 of 100 people: 32 of 56 men (57%) and 16 of 44 women (36%; the opening summary says 34%). Most positive lungs had few bodies, and men were more heavily contaminated. A 'squeezing' method, used on 80 lungs, found bodies in only 17. Among 33 patients with cancer, 12 were positive, compared with 36 of 67 patients with other diseases. The authors said this difference was not statistically significant. Microscope sections of 67 lungs showed no fibrosis consistent with asbestosis. Previous occupation was unknown for 36 of the 56 men, and women were generally listed as housewives, so occupational exposure could not be assessed. The authors concluded that asbestos is probably a significant air contaminant in Montreal, and that results depended on sampling technique.

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 (necropsy) survey: lung smears from random adult necropsies examined for asbestos bodies, comparing two smear techniques
• Who was studied: 100 adults who died and were autopsied at four Montreal hospitals (Royal Victoria Hospital, Montreal Neurological Institute, Montreal General Hospital, St. Mary's Hospital): 56 men and 44 women. 80 lungs were also examined by the squeezing method, and 45 patients had one lung examined by each method. Study dates are not stated.
• Exposure: Presence and amount of asbestos bodies in lung smears, recognized by appearance only and graded from + (fewer than five per slide) to ++++ (an average of five per low-power field). Fiber type was not identified, and occupational exposure could not be assessed.
• Main results:
  • By the scraping method, asbestos bodies were found in 32 of 56 men (57%) and 16 of 44 women (36%). The authors reported the difference as significant (P < .05).
  • Asbestos bodies were generally scanty. Of the 48 positive cases, 35 were graded + (20 men, 15 women), 9 were ++ (8 men, 1 woman), 3 were +++ and 1 was ++++. Men were more heavily contaminated than women.
  • Scraping found asbestos bodies in 48 of 100 lungs (48%), while squeezing found them in 17 of 80 (21%; the discussion gives 21.5%). The authors reported this difference as significant (P < .001).
  • Of the 100 lungs, 40 were positive in the left lower lobe and 39 in the left upper lobe. The authors noted no real difference between lobes. Differences by age and lobe did not reach conventional significance (P approximately 0.1).
  • Among the 33 patients with cancer, 12 had asbestos bodies (36%), compared with 36 of 67 (54%) patients with other diseases. The authors reported the difference as not significant at conventional levels (printed as P < 0.1).
  • In histological sections of 67 lungs, interstitial pulmonary fibrosis consistent with asbestosis was not seen. Asbestos bodies were found in sections in only two cases, one of them a man who had worked as a steam-boiler operator and whose smears were graded +++.
• The authors' conclusion: The authors concluded that asbestos bodies are common in a high proportion of cadavers in Montreal and that asbestos is therefore probably a significant air contaminant. They also stated that asbestos bodies were not more common in patients with malignant disease in their autopsy populations, and that casual exposure to asbestos is not an important cause of malignancy in the general population.
• Limitations the authors state:
  • Clinical histories were inadequate to assess occupational exposure. Previous occupation was unknown for 36 of the 56 men (listed as retired), and women were generally listed as housewives.
  • The number of cases studied was very small.
  • Results depended on the technique and the amount of lung sampled, which made comparison with other surveys difficult. Only the left lung was sampled, and sampling both lungs might have increased the incidence.
  • Asbestos bodies were recognized by appearance only. The authors acknowledged that these structures might not be formed by asbestos fibres at all, though they considered this unlikely.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Autopsy.

Related studies

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• Risk of mesothelioma and occupational exposure to asbestos and man-made vitreous fibers: evidence from two case-control studies in Montreal, Canada — J. Pintos, M.E. Parent, et al. (2009)
• Lung cancer risk among workers in the construction industry: results from two case-control studies in Montreal — A. Lacourt, J. Pintos, et al. (2015)
• Insulation workers in Belfast. 1. Comparison of a random sample with a control population — W.F. Wallace, J.H. Langlands (1971)
• Computer-aided volumetric assessment of malignant pleural mesothelioma on CT using a random walk-based method — M. Chen, E. Helm, et al. (2017)

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