An examination of the fibrous mineral content of asbestos lung tissue from the Canadian chrysotile mining industry

Our plain-English summary of An examination of the fibrous mineral content of asbestos lung tissue from the Canadian chrysotile mining industry, by F.D. Pooley (Environmental Research, 1976).

The study

• Author: F.D. Pooley
• Journal: Environmental Research
• Published: 1976;12(3):281-98
• Cited by: 83 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004984).

Abstract

An examination of postmortem lung tissue from 20 cases of diagnosed asbestosis from the Canadian chrysotile mining industry has shown that fibrous minerals other than chrysotile were present in many of the cases. Tremolite fiber was found in 11 of the cases, often in large amounts, and crocidolite and amosite fibers were found in 2 of the cases. Fibers corresponding to talc and anthophyllite were found in 3 cases. In 4 of the cases fibers were not detected. Amphibole and other fibers were found to be present in larger numbers than chrysotile in 7 of the cases. No attempt has been made to relate the results to occupation and location where the exposures may have occurred. It is possible, however, that fibrous minerals other than chrysotile are active in the incidence of asbestosis in the Canadian chrysotile mining industry.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This study examined postmortem lung tissue from 20 people diagnosed with asbestosis who had worked in the Canadian chrysotile mining industry. The author reduced thin tissue sections to ash and examined the residue under an electron microscope fitted with an X-ray analyzer, to count fibers and identify their mineral type. Average fiber counts varied from 20,000 per microscope grid in 2 cases to no detectable fiber in 4 cases. Fibers other than chrysotile were found in 12 cases. Tremolite was found in 11 cases, crocidolite and amosite in 2, and fibers resembling talc or anthophyllite in 3. In 7 cases the non-chrysotile fibers outnumbered chrysotile. Chrysotile was found in 15 cases, but only 4 contained chrysotile alone. Full work histories were not available, so the author noted that some amphibole exposure may have occurred elsewhere in the asbestos industry. The author concluded that it is possible that fibrous minerals other than chrysotile, such as tremolite, play a role in asbestosis in this industry. The author also concluded that tissue should be examined mineralogically before any single mineral is blamed for a disease.

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: Laboratory mineral analysis of postmortem lung tissue from a series of asbestosis cases, using transmission electron microscopy with energy dispersive X-ray analysis and electron diffraction
• Who was studied: Postmortem lung tissue from 20 cases of diagnosed asbestosis in people who had been employed in the chrysotile mining industry in Canada. The histological material was supplied by Professor A. McDonald of McGill University.
• Exposure: Employment in the Canadian chrysotile mining industry. Table 1 lists places of employment including Thetford, King, Beaver, Jeffry, Flintkote, Normandie, Vimy Ridge and British Columbia. The fibers found in tissue were chrysotile, tremolite, crocidolite, amosite and talc/anthophyllite.
• Main results:
  • The average number of fibers per electron microscope grid varied from 20,000 in 2 cases to no detectable fiber in 4 cases.
  • Fibers other than chrysotile were detected in 12 of the 20 cases.
  • Tremolite fiber was found in 11 of the cases, often in large amounts. Crocidolite and amosite fibers were found in 2 of the cases.
  • Fibers corresponding to talc and anthophyllite were found in 3 cases.
  • In 7 of the cases, non-chrysotile fibers outnumbered chrysotile fibers, often by very large amounts.
  • Chrysotile was found in 15 of the cases, but only 4 cases contained chrysotile fiber only.
  • On average, the amphibole fibers were much larger in diameter and length than the chrysotile particles found.
  • Asbestos bodies were rarely found in any specimen, and most fibers had no visible coating.
• The authors' conclusion: The author concluded that it is possible that fibrous minerals other than chrysotile are active in the incidence of asbestosis in the Canadian chrysotile mining industry. The author also concluded that greater emphasis should be placed on mineral examination of tissue before implicating any single mineral as a cause of disease.
• Limitations the authors state:
  • The total occupational history of the individual cases was not available, and exposure to amphibole fibers may have occurred in other parts of the asbestos industry.
  • No attempt was made to relate the results to occupation and to the location where exposures may have occurred.
  • The fiber counts are comparative only and were influenced by observer error and by how fibers were distributed in the specimens.
  • Some chrysotile fibers were extremely difficult to count, especially aggregates of fibrils, so their numbers were estimated.
  • Not all fibers analyzed chemically were also examined by electron diffraction.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• King Beaver mine, Thetford Mines, Quebec
• Vimy Ridge property (Penhale ore body), 5 miles southwest of Thetford Mines, Quebec

All asbestos mines

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Tremolite, Crocidolite, Amosite, Talc, Anthophyllite, Amphibole Group.

Related studies

• Exposing the "myth" of ABC, "anything but chrysotile": a critique of the Canadian asbestos mining industry and McGill University chrysotile studies — D. Egilman, C. Fehnel, et al. (2003)
• Lung asbestos content in long-term residents of a chrysotile mining town — A. Churg (1986)
• Pulmonary mineral fibers after occupational and environmental exposure to asbestos in the Russian chrysotile industry — A. Tossavainen, E. Kovalevsky, et al. (2000)
• Comprehensive assessment of exposures to elongate mineral particles in the taconite mining industry — J. Hwang, G. Ramachandran, et al. (2013)
• The relationship between various exposure metrics for elongate mineral particles (EMP) in the taconite mining and processing industry — J. Hwang, G. Ramachandran, et al. (2014)
• Fibrous and mineral content of cosmetic talcum products — L.J. Cralley, M.M. Key, et al. (1968)

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