Fibers in lung tissues of mesothelioma cases among miners and millers of the township of Asbestos, Quebec

Our plain-English summary of Fibers in lung tissues of mesothelioma cases among miners and millers of the township of Asbestos, Quebec, by A. Dufresne, M. Harrigan, S. Massé, et al (American Journal of Industrial Medicine, 1995).

The study

• Authors: A. Dufresne, M. Harrigan, S. Massé, R. Bégin
• Journal: American Journal of Industrial Medicine
• Published: 1995;27(4):581-92
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Twenty cases of mesothelioma among miners of the township of Asbestos, Quebec, Canada, have been reported. To further explore the mineral characteristics of various fibrous material, we studied the fibrous inorganic content of postmortem lung tissues of 12 of 20 available cases. In each case, we measured concentrations of chrysotile, amosite, crocidolite, tremolite, talc-anthophyllite, and other fibrous minerals. The average diameter, length, and length-to-diameter ratio of each type of fiber were also calculated. For total fibers > 5 microns, we found > 1,000 asbestos fibers per mg tissue (f/mg) in all cases; tremolite was above 1,000 f/mg in 8 cases, chrysotile in 6 cases, crocidolite in 4 cases, and talc anthophyllite in 5 cases. Among cases with asbestos fibers, the tremolite count was highest in 7 cases, chrysotile in 3 cases, and crocidolite in 2 cases. The geometric mean concentrations of fibers > or = 5 microns were in the following decreasing order: tremolite > crocidolite > chrysotile > other fibers > talc-anthophyllite > amosite. For total fibers < 5 microns, we found > 1,000 fibers per mg tissue (f/mg) in all cases; tremolite was above 1,000 f/mg in 12 cases, chrysotile in 8 cases, crocidolite in 7 cases, and talc-anthophyllite in 6 cases. Tremolite was highest in 8 cases, chrysotile in 2 cases, and crocidolite and amosite in 2 cases. The geometric mean concentrations of fibers < 5 microns were in the following decreasing order: tremolite > other fibers > chrysotile > crocidolite > talc-anthophyllite > amosite. We conclude, on the basis of the lung burden analyses of 12 mesothelioma cases from the Asbestos township of Quebec, that the imported amphibole (crocidolite and amosite) were the dominant fibers retained in the lung tissue in 2/12 cases. In 10/12 cases, fibers from the mine site (chrysotile and tremolite) were found at highest counts; tremolite was clearly the highest in 6, chrysotile in 2, and 2 cases had about the same counts for tremolite and chrysotile. If a relation of fiber burden-causality of mesothelioma is accepted, mesothelioma would be likely caused by amphibole contamination of the plant in 2/12 cases and by the mineral fibers (tremolite and chrysotile) from the mine site in the 10 other cases.

In plain English

The authors measured mineral fibers in postmortem lung tissue from 12 men with mesothelioma who had worked for the same company in the chrysotile mining and milling town of Asbestos, Quebec (12 of 20 available cases). The men had held various jobs in the mine and mill, with on average 31.8 years of exposure. Using electron microscopy, the authors counted chrysotile, amosite, crocidolite, tremolite, talc-anthophyllite and other fibers, separately for fibers shorter than 5 micrometers and those 5 micrometers or longer. Every case had more than 1,000 asbestos fibers per milligram of dry lung tissue in both size groups. Among the longer fibers, tremolite was the most numerous asbestos fiber in 7 cases, chrysotile in 3 and crocidolite in 2. Tremolite had the highest geometric mean concentration in both size groups. The authors concluded that, if fiber burden is accepted as indicating cause, mesothelioma was likely caused by amphibole contamination of the plant in 2 of 12 cases and by mine-site fibers (tremolite and chrysotile) in the other 10. They noted that chrysotile's low durability in the lung makes it hard to relate its lung content to 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: Lung fiber burden analysis of a series of mesothelioma cases: postmortem lung tissue (paraffin blocks) examined by transmission electron microscopy
• Who was studied: 12 male workers with mesothelioma (12 of 20 available cases), all employed by the same company in the town of Asbestos, Quebec, Canada; on average 31.8 years of exposure (standard deviation 10.1)
• Exposure: Work in a chrysotile mine and milling plant, in a variety of jobs with no job category common to all 12 workers; lung content of chrysotile, amosite, crocidolite, tremolite, talc-anthophyllite and other fibers was measured
• Main results:
  • Fiber concentrations in the tables were expressed as fibers per mg of dry weight lung tissue.
  • Fibers 5 micrometers or longer: all 12 cases had more than 1,000 asbestos fibers per mg of tissue. Tremolite was above 1,000 fibers per mg in 8 cases, chrysotile in 6, crocidolite in 4, amosite in 1 and talc-anthophyllite in 5.
  • Fibers 5 micrometers or longer: among asbestos fibers, tremolite was the highest count in 7 cases, chrysotile in 3 cases and crocidolite in 2 cases.
  • Fibers shorter than 5 micrometers: all 12 cases had more than 1,000 asbestos fibers per mg of tissue. Tremolite was above 1,000 fibers per mg in 12 cases, chrysotile in 8, crocidolite in 7, amosite in 2 and talc-anthophyllite in 6.
  • Fibers shorter than 5 micrometers: tremolite was the highest count in 8 cases, chrysotile in 2 cases and crocidolite in 2 cases.
  • Geometric mean concentrations for fibers shorter than 5 micrometers, from highest to lowest: tremolite, other fibers, chrysotile, crocidolite, talc-anthophyllite, amosite.
  • Geometric mean concentrations for fibers 5 micrometers or longer, as stated in the text: tremolite, crocidolite, chrysotile, other fibers, talc-anthophyllite, amosite. Table VI as printed does not list the values in this same order (see text problems).
  • In both size groups, the geometric mean length-to-diameter ratio was highest for chrysotile, followed by crocidolite, amosite, tremolite, talc-anthophyllite and other fibers.
  • Many chrysotile fibers showed loss (leaching) of magnesium.
  • In 10 of 12 cases, fibers from the mine site (chrysotile and tremolite) had the highest counts. Tremolite was clearly highest in 6 cases, chrysotile in 2, and 2 cases had about equal tremolite and chrysotile counts. In the other 2 of 12 cases, crocidolite and amosite were the dominant fibers retained.
• The authors' conclusion: The authors concluded that, if a fiber burden-causality relationship for mesothelioma is accepted, mesothelioma was likely caused by amphibole contamination of the plant in 2 of 12 cases and by mineral fibers from the mine site (tremolite and chrysotile) in the other 10 cases.
• Limitations the authors state:
  • Only paraffin block specimens were available; fresh tissue was not examined.
  • Because chrysotile has relatively low durability in lung tissue, it is difficult if not impossible to relate chrysotile lung content to asbestos-related disease in humans.

Mines named here

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

• Jeffrey mine, Asbestos, Quebec

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite, Anthophyllite, Chrysotile, Crocidolite, Lung cancer, Mesothelioma, Tremolite.

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

Related studies

• Lung mineral fibers of former miners and millers from Thetford-Mines and asbestos regions: a comparative study of fiber concentration and dimension — A. Nayebzadeh, A. Dufresne, et al. (2001)
• Mesothelioma in Quebec chrysotile miners and millers: epidemiology and aetiology — A.D. McDonald, B.W. Case, et al. (1997)
• The 1891-1920 birth cohort of Quebec chrysotile miners and millers: mortality 1976-88 — J.C. McDonald, F.D. Liddell, et al. (1993)
• Fiber burden and patterns of asbestos-related disease in chrysotile miners and millers — A. Churg, J.L. Wright, et al. (1993)
• The 1891-1920 birth cohort of Quebec chrysotile miners and millers: development from 1904 and mortality to 1992 — F.D. Liddell, A.D. McDonald, et al. (1997)
• The combination of effects on lung cancer of cigarette smoking and exposure in quebec chrysotile miners and millers — F.D. Liddell, B.G. Armstrong (2002)

Browse more research in American Journal of Industrial Medicine, or return to medical research.