Rapporteur's Report Session 4: grunerite asbestos (amosite) and tremolite-ferroactinolite asbestos: risk of environmental mesothelioma

Our plain-English summary of Rapporteur's Report Session 4: grunerite asbestos (amosite) and tremolite-ferroactinolite asbestos: risk of environmental mesothelioma, by J.F. Gamble (Regulatory Toxicology and Pharmacology, 2008).

The study

• Author: J.F. Gamble
• Journal: Regulatory Toxicology and Pharmacology
• Published: 2008;52(1 Suppl):S121-3
• Read it: PubMed · Publisher

In plain English

This article was a rapporteur's report summarizing four papers from a session on environmental mesothelioma, not an original study. A South African review (White, Nelson and Murray) reported that 23% of known mesothelioma cases were attributed to environmental exposure. About 90% were due to crocidolite and about 10% to amosite or mixed fiber, though the report did not say whether these shares were of all known or only environmental cases; no cases were attributed to chrysotile. Price argued that Libby, Montana residents without occupational exposure were not at increased risk of lung cancer, mesothelioma, asbestosis or pleural abnormalities. Constantopoulos reviewed non-occupational exposures: erionite and mesothelioma in Cappadokia, Turkey; tremolite asbestos and mesothelioma in Cyprus; mesothelioma and lung cancer in New Caledonia; and pleural plaques in Corsica. The author asked whether the differing patterns in Cyprus, Corsica and New Caledonia reflected exposure, susceptibility, fiber properties or other factors. Brunner and colleagues found that 5% of 340 male mesothelioma cases in Minnesota had worked in iron mining. They concluded that commercial asbestos exposure was a likely cause in this case series.

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: Rapporteur's report summarizing and commenting on four conference session papers (reviews and a case series); not an original study by the author
• Who was studied: Populations covered by the four summarized papers: South African mesothelioma cases; residents and workers of Libby, Montana; villagers in Cappadokia (Turkey), Cyprus, Corsica and New Caledonia; and 340 male mesothelioma cases identified in Minnesota from 1988 to 1996, some of them iron miners
• Exposure: Covered across the four papers: crocidolite, amosite and chrysotile in South Africa; Libby vermiculite containing asbestiform amphibole ('Libby Asbestos'); erionite (a fibrous zeolite) in Cappadokia; tremolite or tremolite-actinolite asbestos in Cyprus and New Caledonia; surface asbestos deposits in Corsica (fiber type printed as '(tremolite?)'); commercial asbestos and taconite in Minnesota iron mining
• Main results:
  • South African review (White et al.): overall 23% of known mesothelioma cases were attributed to environmental (not occupational) exposure, and about 90% were due to crocidolite asbestos; the report does not state clearly whether the 90% refers to all known cases or only the environmental cases
  • South African review: about 10% of cases were related to amosite or mixed fiber (amosite plus crocidolite), and no cases were attributed to chrysotile exposure
  • Libby paper (Price): proportional mortality ratios for mesothelioma ranged from 1.2% to 4.2% in the two occupational cohorts, compared with 0.2% for the US population
  • Libby paper: the EPA risk assessment estimated about a 0.01% risk of mesothelioma for the highest-exposed Libby resident, and Price suggested the risk was negligible
  • Libby paper: Price stated that an ATSDR finding of increased asbestosis mortality among Libby residents was misleading, because 11 of the 12 deaths were mine workers
  • Constantopoulos paper: in Cappadokia, Turkey, where people lived in caves in volcanic rock containing erionite, half the population died of mesothelioma at ages 35 to 55
  • Constantopoulos paper: in Cyprus, 12 additional mesothelioma cases were found among miners, wives of miners and non-miners, and tremolite-actinolite asbestos was considered the cause in all cases
  • Constantopoulos paper: in Corsica, 4% of chrysotile miners had pleural plaques, compared with 41% of a sample of residents in a nearby village; the report lists Corsica as having pleural plaques with no mention of mesothelioma
  • Constantopoulos paper: in New Caledonia, a high incidence of mesothelioma and lung cancer among women was associated with non-occupational exposure to tremolite asbestos in whitewash applied to home walls
  • Minnesota paper (Brunner et al.): of 15 iron-miner cases with sufficient work histories, 14 had worked in jobs with possible or probable asbestos exposure
  • Minnesota paper: exposure to commercial asbestos in mining jobs was identified for four miners, in jobs such as carpenter, maintenance mechanic and plumber
  • The author judged the Minnesota authors' conclusions reasonable, given their extensive and blinded assessment of exposures
• The authors' conclusion: The report gave no single overall conclusion. In discussing the Constantopoulos paper, the author asked whether the differing findings in Cyprus (mesothelioma), Corsica (pleural plaques) and New Caledonia (mesothelioma and lung cancer) were contradictory, or reflected differences in exposure, susceptibility, fiber properties, a combination of these, or an undiscovered factor. The author judged the Minnesota paper's conclusions reasonable
• Limitations the authors state:
  • The Minnesota authors, as reported, stated that case series studies must be cautiously interpreted
  • The Minnesota study could not further evaluate taconite as a possible cause of mesothelioma, because only one miner lacked identifiable asbestos exposure
  • The author noted that the Libby paper's claim that pleural abnormalities were near the internal background rate needed further explanation

Topics

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

Medical terms in this study, explained in our Lexicon: Grunerite, Amosite, Tremolite, Ferro-actinolite, Environmental Mesothelioma.

Related studies

• Rapporteur's Report Session 3: exposure to grunerite (amosite) asbestos: historical perspectives of the health effects — G.W. Gibbs (2008)
• Rapporteur's Report Session 5: assessment of health risk associated with exposure to non-asbestiform amphiboles including ingestion studies — B. Price (2008)
• Environmental mesothelioma associated with tremolite asbestos: lessons from the experiences of Turkey, Greece, Corsica, New Caledonia and Cyprus — S.H. Constantopoulos (2008)
• Sumas Mountain chrysotile induces greater lung fibrosis in Fischer344 rats than Libby amphibole, El Dorado tremolite, and Ontario ferroactinolite — J.M. Cyphert, A. Nyska, et al. (2012)
• Interpretation of the carcinogenicity of amosite asbestos and ferroactinolite on the basis of retained fiber dose and characteristics in vivo — P.M. Cook, L.D. Palekar, et al. (1982)
• Correlation of in vitro and in vivo methods by means of mass dose and fiber distribution for amosite and fibrous ferroactinolite — D.L. Coffin, L.D. Palekar, et al. (1983)

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