On talc, tremolite, and tergiversation. Ter-gi-ver-sate: 2: to use subterfuges

Our plain-English summary of On talc, tremolite, and tergiversation. Ter-gi-ver-sate: 2: to use subterfuges, by B.W. Case (British Journal of Industrial Medicine, 1991).

The study

• Author: B.W. Case
• Journal: British Journal of Industrial Medicine
• Published: 1991;48(5):357-9
• Type of article: Comment, Letter
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Summary of the article

In this letter, Case responded to an article by Reger and Morgan (1990), which he said read the literature selectively in trying to show that "non-asbestiform" tremolite is not hazardous. He posed three questions: whether non-asbestiform fibres can be unambiguously identified, whether they occur without asbestiform fibres in the same material, and whether they lack biological effects. He answered no to all three. He cited the American Thoracic Society statement that the distinction between cleavage fragments and asbestiform fibres is "in practice extremely murky", and Pooley's description of morphologies as points on a continuum. He argued that microscopic dimensions, not mineralogical definitions, matter for health and regulation, because there is no evidence that cells distinguish fibres of equivalent dimensions. He noted that the US Consumer Product Safety Commission's refusal to ban tremolite-containing play sand was a split decision. He cited evidence that tremolite-actinolite causes lung cancer, mesothelioma and interstitial fibrosis in vermiculite miners. He stressed that pulmonary fibrosis is the most important health effect of talc and non-asbestiform tremolite, citing Merewether's 1933 report of 11 rubber tyre workers. He criticised how animal studies by Stanton et al and by Addison and Davis had been interpreted, noting that one tremolite characterised as fibrous but not asbestiform produced mesothelioma in 70% of animals. He concluded that exempting non-asbestiform fibres from regulation would be folly. The original authors' reply, which disputed these points, is partly included.

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 is a letter to the editor, not a research study, and it reports no new data. B W Case wrote it in reply to a 1990 article by Reger and Morgan about "non-asbestiform" tremolite and talc. Case posed three questions: whether non-asbestiform fibres can be clearly identified, whether they occur without asbestiform fibres, and whether they tell us about the biological effects of long, thin, durable fibres. He answered no to all three. He argued that microscopic fibre shape is what counts for health. He said Reger and Morgan left out other researchers' evidence linking tremolite-actinolite to lung cancer, mesothelioma and interstitial fibrosis in vermiculite miners. He also said they left out lung fibrosis from talc, citing Merewether's 1933 report of 11 rubber tyre workers. He noted that one tremolite described as fibrous but not asbestiform produced mesothelioma in 70% of animals in Addison and Davis's work. He accepted that more work is needed. Case concluded that exempting these fibres from regulation "seems folly" until evidence shows they are easily defined, clearly separated from tremolite asbestos at work, and do not cause lung fibrosis or other health effects.

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: Letter to the editor (correspondence) commenting on a published article; no original data
• Who was studied: No study population; the letter discusses published studies and regulatory documents
• Exposure: So-called "non-asbestiform" tremolite (including fibrous cleavage fragments) and talc; tremolite-actinolite in vermiculite is also mentioned
• Main results:
  • The author argued that, for regulatory and health purposes, fibre shape and size as seen under the microscope matter more than mineralogical definitions.
  • The author cited Pooley as saying that differences between massive, acicular and fibrous forms are not sharply defined but lie on a continuum.
  • The author said Reger and Morgan left out evidence (McDonald et al.) that tremolite-actinolite causes lung cancer, mesothelioma and interstitial fibrosis in vermiculite miners.
  • The author called pulmonary fibrosis the most important dose-related effect of talc and "non-asbestiform" tremolite. He cited Merewether's 1933 report of 11 rubber tyre workers with diffuse interstitial fibrosis on x ray, attributed to fine talc dust, with 13 more workers added the next year.
  • The author said that in work by Addison and Davis and by Davis et al, one tremolite described before the experiment as fibrous but not asbestiform produced mesothelioma in 70% of animals.
  • The author said Reger and Morgan misread Stanton et al's animal study. He stated that six of the seven talc preparations used there contained no fibres in the Stanton size range.
• The authors' conclusion: The author concluded that until there is evidence that "non-asbestiform" fibres are easily defined, clearly separated from tremolite asbestos in real work settings, and do not cause lung fibrosis or other health effects, it seems folly to exempt them from regulation.
• Limitations the authors state:
  • The author accepted that more research is needed on whether mineral characteristics play a role in the health effects of tremolite fibres.

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: Talc, Tremolite, Non-Asbestiform, Asbestiform, Cleavage Fragment, Actinolite, Lung Cancer, Mesothelioma.

Related studies

• On talc, tremolite, and tergiversation — A.M. Langer, R.P. Nolan, et al. (1991)
• On talc, tremolite, and tergiversation — R. Reger, W.K. Morgan (1990)
• Association of Metsovo lung and pleural mesothelioma with exposure to tremolite-containing whitewash — A.M. Langer, R.P. Nolan, et al. (1987)
• An epidemiological study in an Anatolian village environmentally exposed to tremolite asbestos — Y.I. Baris, N. Bilir, et al. (1988)
• Radiological survey of past and present vermiculite miners exposed to tremolite — J.C. McDonald, P. Sebastien, et al. (1986)
• The dust hazard in tremolite talc mining — L. Greenburg (1947)

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