Malignant mesothelioma caused by childhood exposure to long-fiber low aspect ratio tremolite

Our plain-English summary of Malignant mesothelioma caused by childhood exposure to long-fiber low aspect ratio tremolite, by F. Magee, J.L. Wright, N. Chan, et al (American Journal of Industrial Medicine, 1986).

The study

• Authors: F. Magee, J.L. Wright, N. Chan, L. Lawson, A. Churg
• Journal: American Journal of Industrial Medicine
• Published: 1986;9(6):529-33
• Type of article: Case report
• Cited by: 22 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. 001145).

Abstract

A 41-year-old man was found to have a malignant mesothelioma of the pleura. During childhood in Corsica, he had been exposed at home to chrysotile ore from the Canari mine. Analysis of lung mineral content revealed background levels of chrysotile but an elevated level of tremolite and actinolite asbestos. The latter had a geometric mean length of 3.7 microns, a value considerably longer than we have found for tremolite and actinolite from Quebec chrysotile miners but roughly the same as the mean length of amosite and crocidolite in workers with occupational amphibole exposure. No tremolite or actinolite fibers of length greater than 8 microns microns and width less than 0.25 micron were observed. The mean aspect ratio of the tremolite and actinolite fibers was 7, a value similar to that found in chrysotile miners with mesothelioma but considerably less than the mean aspect ratio of amosite and crocidolite from those with occupational exposure. These data suggest that long-fiber tremolite is a potential mesothelial carcinogen in humans, and that fiber length is more important than fiber aspect ratio in this regard.

In plain English

This case report describes a 41-year-old man with malignant mesothelioma of the pleura (the lining around the lung). Tissue examination showed no evidence of asbestosis, and no pleural plaques were present. Until age 11 he lived in Corsica, about 20 km from the Canari chrysotile mine. Family members, including him, took dusty ore from mine trucks that stopped at a pub an uncle ran in the house, and used it to filter wine. He denied asbestos exposure in his later work. The authors dissolved lung tissue and examined the recovered fibers by electron microscope. His chrysotile level was within the general population's range. His tremolite and actinolite level was slightly elevated, but far lower than in chrysotile miners with mesothelioma. These fibers were long (geometric mean length 3.7 microns) but had a low geometric mean length-to-width ratio of 7. No fibers longer than 8 microns and narrower than 0.25 microns were found. The authors noted that one case limits conclusions and that other exposures were possible. They concluded that fiber length may matter more than this ratio in causing mesothelioma.

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: case report (single patient), with electron-microscope analysis of mineral fibers recovered from dissolved lung tissue, compared against groups previously reported by the same laboratory
• Who was studied: One 41-year-old man admitted in November 1984 with a right-sided pleural effusion, diagnosed with tubulopapillary malignant mesothelioma of the pleura. He had no histologic evidence of asbestosis and no pleural plaques. He had lived in Corsica until age 11 and later lived in France and Canada.
• Exposure: Childhood household exposure in Corsica to chrysotile ore from the Canari mine, which the authors say contained long-fiber tremolite. Family members took ore from trucks stopping at a pub an uncle ran in the house and used it to filter wine. The authors presumed this was the important exposure but said other exposures (asbestos outcrops, crushed serpentine road paving) were possible. The patient denied asbestos exposure in his later work as a pulp mill engineer and office worker.
• Main results:
  • The patient's lung chrysotile burden was within the general population range. His lung contained more tremolite than chrysotile.
  • His tremolite (tremolite and actinolite) level was slightly elevated compared with the general population of Vancouver, but two orders of magnitude less than in five chrysotile miners with mesothelioma.
  • His tremolite concentration was quite similar to the mean amosite and crocidolite values in a series of shipyard and insulation workers with mesothelioma.
  • The tremolite and actinolite fibers in this case had a geometric mean length of 3.7 microns. This is considerably longer than the authors found for tremolite and actinolite in Quebec chrysotile miners.
  • About 37% of the tremolite and actinolite fibers in this case were longer than 5 microns, 6% were longer than 10 microns, and 0.5% were longer than 20 microns.
  • The aspect ratio (length to width) of the tremolite and actinolite fibers in this case was 7, reported in Table II as a geometric mean. This was similar to chrysotile miners with mesothelioma and considerably less than amosite and crocidolite in occupationally exposed workers.
  • No fibers longer than 8 microns and narrower than 0.25 microns were found in this case.
• The authors' conclusion: The authors concluded that their data imply long-fiber, low aspect ratio tremolite is a mesothelial carcinogen at about the same lung burden as equally long but much higher aspect ratio amosite or crocidolite. They also concluded that fiber length may be more important than high aspect ratio in human mesothelial carcinogenesis.
• Limitations the authors state:
  • The authors state it is difficult to draw conclusions from a single case.
  • The authors note that exposures other than the Canari mine product were possible, given widespread asbestos outcrops in Corsica and the use of crushed serpentine for paving roads there.

Mines named here

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

• Canari mine, Corsica

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma, Tremolite.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Aspect Ratio (Length-to-diameter ratio), Tremolite, Pleura, Chrysotile, Actinolite, Quebec Chrysotile, Amosite.

Related studies

• Tremolite/chrysotile ratios — G. Scansetti, G. Piolatto (1987)
• Radiological survey of past and present vermiculite miners exposed to tremolite — J.C. McDonald, P. Sebastien, et al. (1986)
• Chrysotile, tremolite, and malignant mesothelioma in man — A. Churg (1988)
• Cohort study of mortality of vermiculite miners exposed to tremolite — J.C. McDonald, A.D. McDonald, et al. (1986)
• Mesothelioma in Cyprus: the role of tremolite — K. McConnochie, L. Simonato, et al. (1987)
• Association of Metsovo lung and pleural mesothelioma with exposure to tremolite-containing whitewash — A.M. Langer, R.P. Nolan, et al. (1987)

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