Re: Brent L. Finley, Stacey M. Benson & Gary M. Marsh (2017): Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology, Inhalation Toxicology, DOI: 10.1080/08958378.2017.1336187

Our plain-English summary of Re: Brent L. Finley, Stacey M. Benson & Gary M. Marsh (2017): Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology, Inhalation Toxicology, doi:10.1080/08958378.2017.1336187, by M.M. Finkelstein (Inhalation Toxicology, 2017).

The study

• Author: M.M. Finkelstein
• Journal: Inhalation Toxicology
• Published: 2017;29(9):387-388
• Type of article: Letter, Comment
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this letter, the author responded to a pooled analysis by Finley and colleagues of three epidemiologic studies of cosmetic talc miners. That analysis had found no deaths from mesothelioma in about 99,000 person-years of observation and concluded that there was no epidemiological evidence linking cosmetic talc exposure to pleural mesothelioma. The author argued that the national and regional mesothelioma rates used as comparisons were unsuitable. Those rates would be dominated by heavily exposed workers in manufacturing, shipyards and construction, so a relative risk below 1.0 would be expected for talc miners exposed to low levels of asbestos contamination. As a thought experiment, he compared the talc miners with Quebec chrysotile miners and millers, whose average mesothelioma mortality was 25 per 100,000 person-years (McDonald et al. 1997). If talc miners' asbestos exposures were 10% or 1% of the Quebec levels, 2.5 or 0.25 mesothelioma cases would be expected in 99,000 person-years. Using the Poisson distribution, the chance of observing no cases was 8% and 78%, respectively. A 50/50 chance of observing no cases corresponded to exposure of about 3% of the Quebec level. The author concluded that the evidence was too weak to draw conclusions about risk at these low exposures and that a much larger cohort would be required. He disclosed consulting for American attorneys in cosmetic talc litigation.

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 a letter to the editor responding to a pooled analysis by Finley and colleagues of three studies of cosmetic talc miners. The letter reported no new data. Finley and colleagues had found no mesothelioma deaths among 99,000 person-years of observation. The author argued that comparing talc miners with national and regional mesothelioma rates is a problem, because those rates include heavily exposed workers. In a 'thought experiment,' the author used Quebec chrysotile miners and millers (McDonald et al., 1997), averaging 25 mesothelioma deaths per 100,000 person-years, as a reference. If talc miners' asbestos exposures were 10% of Quebec levels, about 2.5 cases would be expected, with an 8% chance of seeing none. At 1%, 0.25 cases would be expected, with a 78% chance of seeing none. At about 3% of Quebec exposure, seeing no cases and seeing one or more were equally likely. The author concluded that the evidence was too weak to draw conclusions about risk at talc miners' low exposures, and that a much larger cohort would be needed.

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 (commentary with an illustrative calculation; no new study data)
• Who was studied: No new population was studied. The letter discusses the pooled analysis by Finley and colleagues of three cohorts of cosmetic talc miners (99,022 person-years), compared hypothetically with the Quebec chrysotile miners and millers reported by McDonald et al. (1997).
• Exposure: Asbestos contamination in cosmetic talc mining, described as low. The author assumed talc miners' asbestos dust exposures were 10% or 1% of those in Quebec chrysotile mining.
• Main results:
  • As described by the author, the Finley pooled analysis found no mesothelioma deaths among 99,000 person-years in the three cosmetic talc miner cohorts.
  • The author argued that national and regional comparison rates include heavily exposed workers. As a result, talc miners' relative risk would be expected to be below 1.0.
  • Using rates reported by McDonald et al. (1997) for Quebec chrysotile miners and millers, the author used an average of 25 mesothelioma deaths per 100,000 person-years.
  • Under the 10% assumption, the author calculated that about 2.5 mesothelioma cases would be expected in the pooled talc cohort. Under the 1% assumption, about 0.25 cases would be expected.
  • Based on the Poisson distribution, there was an 8% chance of observing no cases when 2.5 were expected (the 10% exposure assumption).
  • There was a 78% probability of observing no cases when 0.25 were expected (the 1% exposure assumption).
  • An exposure of about 3% of that of the Quebec chrysotile miners and millers gave a 50/50 chance of observing no cases versus one or more cases.
• The authors' conclusion: The author concluded that, despite 100,000 person-years from three pooled cohorts, the epidemiologic evidence was too weak to draw conclusions about the risk from talc miners' low asbestos exposures. In the author's view, a much larger cohort would be needed to conclude there is no risk.
• Limitations the authors state:
  • The author stated that a reference population free of occupationally exposed people cannot be found. The Quebec comparison was therefore presented as a hypothetical 'thought experiment' based on assumed exposure levels.

Topics

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

Medical terms in this study, explained in our Lexicon: Cosmetic Talc, Pleural Mesothelioma, Epidemiology, Meta-Analysis, Mesothelioma, Relative Risk, Talc, Quebec Chrysotile.

Related studies

• Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology — B.L. Finley, S.M. Benson, et al. (2017)
• Letter on: "Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology" — D. Mirabelli (2017)
• Response to letters regarding "Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology" — B.L. Finley, S.M. Benson, et al. (2018)
• Letter concerning: Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period by Gary M. Marsh et al. (Inhal Toxicol. 2019 Aug 5:1-11. doi:10.1080/08958378.2019.1645768) — M.M. Finkelstein (2019)
• A quantitative weight of evidence assessment of Hill's guidelines for causal inference for cosmetic talc as a cause of mesothelioma — A.M. Ierardi, A. Urban, et al. (2021)
• Absence of mesothelioma risk maintained in an expanded international cohort of cosmetic talc miners and millers — A.M. Ierardi, G.M. Marsh (2020)

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