Health effects of tremolite. This official statement of the American Thoracic Society was adopted by the ATS Board of Directors, June 1990

Our plain-English summary of Health effects of tremolite. This official statement of the American Thoracic Society was adopted by the ATS Board of Directors, June 1990 (The American Review of Respiratory Disease, 1990).

The study

• Journal: The American Review of Respiratory Disease
• Published: 1990;142(6 Pt 1):1453-8
• Type of article: Review
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In 1988 the American Thoracic Society appointed a committee to critically assess scientific knowledge of health risks from tremolite, an amphibole that contaminates chrysotile, talc and vermiculite deposits. A draft was presented at a public forum in May 1989 and revised after comments, and the statement was adopted in June 1990. The committee reviewed epidemiologic, lung-burden, animal and mineralogic evidence and commented on OSHA regulatory issues. Because mineralogists disagreed, it largely treated cleavage fragments and asbestiform fibers together as "fibers." Montana vermiculite miners had four mesotheliomas and a dose-related excess of lung cancer (15 observed, 5.3 expected, 20 years or more from hire; SMR 2.85). Talc studies had not convincingly shown an exposure-related cancer risk. Elevated mesothelioma risk had been observed in rural areas of Turkey with naturally occurring asbestiform tremolite. Lung-burden evidence implied that long, high-aspect-ratio tremolite fibers were particularly dangerous because of their propensity to induce mesothelioma. Animal studies showed tremolite to be a powerful mesothelial carcinogen. The committee concluded that tremolite asbestos had unquestioned health effects in humans and animals, identical to those of other forms of asbestos. It found that evidence for biologic distinctions based on mineralogic parameters other than fiber dimension and fiber number was inadequate. It also concluded that appropriately sized tremolite "fibers," in sufficient exposure dose, should be regarded as capable of producing the recognized asbestos-related diseases and regulated accordingly. It recommended further research.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This was an official statement of the American Thoracic Society. A committee reviewed research on the health effects of tremolite, an amphibole fiber that contaminates chrysotile, vermiculite and talc ores. It was a review, not a new study. In the reviewed work, a cohort of Libby, Montana vermiculite workers had four mesothelioma cases. Among these workers, 20 or more years from hire, there were 15 lung cancer deaths against 5.3 expected, a standardized mortality ratio of 2.85, and lung cancer risk was related significantly to estimated cumulative exposure. The committee urged caution because this cohort had not been replicated. It found that no talc study convincingly showed a lung cancer risk reliably attributed to exposure. Elevated mesothelioma risk had been observed among rural residents of Turkey with naturally occurring asbestiform tremolite. In animal test systems, the committee judged tremolite a powerful mesothelial carcinogen. The authors concluded that appropriately sized tremolite fibers, at sufficient dose, should be regarded as capable of producing the recognized asbestos-related diseases and regulated accordingly. They had largely set aside the disputed distinction between cleavage fragments and asbestiform fibers.

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: Official statement of the American Thoracic Society; committee review of epidemiologic, animal and mineralogic (lung burden) evidence, with comment on regulatory issues
• Who was studied: Reviewed studies of workers exposed through tremolite contamination of chrysotile, vermiculite and talc ores, residents of regions in Turkey with natural deposits, lung burden studies, and animal experiments
• Exposure: Tremolite, an amphibole fiber with little commercial use, both asbestiform and nonasbestiform (including cleavage fragments), occurring as a contaminant of chrysotile, vermiculite and talc and as a natural deposit
• Main results:
  • Reviewed Libby, Montana vermiculite cohort (workers employed at least one year): four cases of mesothelioma
  • Libby cohort, 20 years or more from hire: 15 lung cancers observed against 5.3 expected, a standardized mortality ratio of 2.85; lung cancer risk related significantly to estimated cumulative exposure
  • Libby cohort: lung cancer risk related significantly to estimated cumulative exposure
  • Reviewed South Carolina vermiculite cohort (194 subjects): four lung cancer deaths versus 3.3 expected, and no mesothelioma or pneumoconiosis cases
  • Unpublished NIOSH data on a New York talc mine, 20 years or more after hire: the only significantly elevated lung cancer risk was among workers employed less than one year (eight observed, 2.24 expected, SMR 357.2)
  • Committee's assessment of the talc studies: none convincingly demonstrated an increased lung cancer risk reliably attributed to exposure
  • Elevated mesothelioma risk reported among inhabitants of rural areas in Turkey with naturally occurring asbestiform tremolite
  • Most mesothelioma cases from the Quebec chrysotile mining regions, especially the Thetford mines region, had only tremolite and chrysotile in their lungs, with more tremolite than chrysotile
  • Reviewed inhalation experiment (Davis and coworkers) with asbestiform Korean tremolite: two mesotheliomas and 16 carcinomas in 40 animals, and no tumors in control animals
  • Committee's assessment of the animal studies: tremolite is a powerful mesothelial carcinogen in these test systems
• The authors' conclusion: The authors concluded that, as prudent public health policy, appropriately sized tremolite fibers at sufficient exposure dose (concentration and duration) should be regarded as capable of producing the recognized asbestos-related diseases and should be regulated accordingly
• Limitations the authors state:
  • Because mineralogists disagree, the committee largely ignored the distinction between cleavage fragments and asbestiform fibers and treated most data as based on fibers of various sizes
  • The dose-response evidence for vermiculite rests on a single, nonreplicated cohort (Libby)
  • In lung burden studies, the populations also had very high chrysotile exposure, so the roles of chrysotile and tremolite could not be separated
  • Few animal studies have used tremolite

Topics

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

Medical terms in this study, explained in our Lexicon: Tremolite, Amphibole Group, Chrysotile, Talc, vermiculite, OSHA, Cleavage Fragment, Asbestiform.

Related studies

• Pulmonary changes after exposure to vermiculite contaminated with fibrous tremolite — J.E. Lockey, S.M. Brooks, et al. (1984)
• Health of vermiculite miners exposed to trace amounts of fibrous tremolite — J.C. McDonald, A.D. McDonald, et al. (1988)
• Cohort study of mortality of vermiculite miners exposed to tremolite — J.C. McDonald, A.D. McDonald, et al. (1986)
• Radiological survey of past and present vermiculite miners exposed to tremolite — J.C. McDonald, P. Sebastien, et al. (1986)
• Health effects of tremolite. Now and in the future — B.W. Case (1991)
• Chrysotile, tremolite, and malignant mesothelioma in man — A. Churg (1988)

Browse more research in The American Review of Respiratory Disease, or return to medical research.