Absence of mesothelioma risk maintained in an expanded international cohort of cosmetic talc miners and millers

Our plain-English summary of Absence of mesothelioma risk maintained in an expanded international cohort of cosmetic talc miners and millers, by A.M. Ierardi, G.M. Marsh (Inhalation Toxicology, 2020).

The study

• Authors: A.M. Ierardi, G.M. Marsh
• Journal: Inhalation Toxicology
• Published: 2020;32(6):257-264
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Based on novel information for the Vermont cosmetic talc miner/miller cohort, including a reported case of mesothelioma, we sought to update our prior pooled statistical power analyses of mesothelioma incidence among European cosmetic talc miners/millers. With the inclusion of the Vermont cohort, we expanded our pooled analysis by 17,170 person-years of observation.Methods: Cosmetic talc miner/miller cohort studies conducted in Italy, Norway, France, Austria, and Vermont were pooled. The expected numbers of mesothelioma cases for each cohort as reported in these studies were used. Our statistical power analysis was based on an a priori one-sided significance level of 0.05 and Poisson distribution probabilities.Results: A total of 130,514 person-years of observation was generated across the five cohorts. One case of mesothelioma was observed (in the Vermont cohort), while approximately 3.34 cases (a mid-value estimate) were expected overall. Thus, we found that the pooled cohorts had 59% and 78% power to detect a 2.5-fold or greater and a 3.0-fold or greater increase in mesothelioma, respectively. The work history characteristics of the one mesothelioma case, which included mention of prior asbestos exposure on the case's death certificate, do not support a causal link with cosmetic talc exposure.Conclusions: Despite the recent finding of one case of mesothelioma in the Vermont cohort (a case unlikely related to talc exposure), we continue to conclude that the epidemiological evidence from the cosmetic talc miner/miller cohort studies does not support the hypothesis that cosmetic talc exposures are associated with an increased risk of pleural mesothelioma.

In plain English

This paper pooled five published cohorts of cosmetic talc miners and millers (Italy, Norway, France, Austria, Vermont) to update the authors' earlier mesothelioma power analyses. Expected counts for the European cohorts came from the original authors. The Vermont update had not calculated one. Instead, it approximated the count as Norway's expected pleural cancers (0.60), and a later letter gave 0.17 to 0.34. All three were used. Across 130,514 person-years, one mesothelioma was observed, in the Vermont cohort. Depending on the Vermont estimate, 3.17, 3.34 or 3.60 cases were expected. For 3.34, the standardized mortality ratio was 0.299 (95% CI 0.015 to 1.42), and none of the three exceeded 1.00. With 3.34 expected, power was 59% to detect a 2.5-fold or greater increase and 78% for a 3.0-fold or greater increase. The Vermont case had worked in talc under 5 years, and the death certificate mentioned asbestos exposure. The authors judged it unlikely to be talc-related. They concluded the cohort evidence does not support an association between cosmetic talc exposure and increased pleural mesothelioma risk. They could not update their earlier latency analysis for Vermont.

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: Pooled statistical power analysis of five previously published cohort studies, with no new data collected. For the four European cohorts it used expected counts reported by the original study authors. For Vermont it used three estimates: 0.60 from the Vermont update itself (Fordyce et al. 2019), and 0.17 and 0.34 from a later letter by the same authors (Fordyce et al. 2020).
• Who was studied: Cosmetic talc miners and millers in five cohorts (Italy, Norway, France, Austria, Vermont USA), 4,151 workers in total according to Table 1, giving 130,514 person-years. The Vermont cohort contributed 427 workers and 17,170 person-years.
• Exposure: Employment as a cosmetic talc miner or miller. This analysis used no individual exposure measurements.
• Main results:
  • The Vermont cohort update (Fordyce et al. 2019) had not calculated an expected mesothelioma count. Instead, it approximated the count as equal to the Norwegian cohort's expected pleural cancers (0.60). A later letter by the same authors (Fordyce et al. 2020) calculated 0.17 to 0.34 from US SEER data. The authors of this paper used all three estimates.
  • One case of mesothelioma was observed across all five pooled cohorts, in the Vermont cohort
  • Total expected mesothelioma cases in the pooled cohorts were 3.17, 3.34 or 3.60, depending on which estimate was used for the Vermont cohort
  • Standardized mortality ratios for the pooled cohort were 0.315 (95% CI 0.016 to 1.50), 0.299 (95% CI 0.015 to 1.42) and 0.278 (95% CI 0.014 to 1.32). None was above 1.00.
  • With the mid-value of 3.34 expected cases, the pooled cohorts had 59% power to detect a 2.5-fold or greater increase in mesothelioma and 78% power to detect a 3.0-fold or greater increase. With 3.17 or 3.60 expected cases, the corresponding power values were 0.68 and 0.84 (Table 2).
  • To reject the hypothesis of no association at the 0.05 level, 7 or more mesotheliomas would have had to be observed with 3.17 expected, and 8 or more with 3.34 or 3.60 expected
  • According to the Vermont study the authors cited (Fordyce et al. 2019), the one case worked in the talc industry for less than 5 years and died 30 years after employment, and the death certificate mentioned asbestos exposure. The authors considered the case unlikely to be directly related to Vermont talc employment.
• The authors' conclusion: The authors concluded that, despite the one Vermont case (which they considered unlikely to be related to talc), the epidemiological evidence from the cosmetic talc miner/miller cohorts does not support the hypothesis that cosmetic talc exposures are associated with an increased risk of pleural mesothelioma.
• Limitations the authors state:
  • The authors could not update their previous latency analysis because adequate information was lacking for the Vermont cohort
  • The expected number of mesotheliomas for the Vermont cohort was uncertain, so the authors used three estimates (0.17, 0.34 and 0.60)
  • Some power values followed an irregular pattern because of the small number of events and the discrete nature of the Poisson distribution

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Cosmetic Talc, Meta-Analysis, Work History, Asbestos Exposure, Death Certificate, Talc, Pleural Mesothelioma.

Related studies

• Confidence interval function analysis to evaluate the risk of mesothelioma among an expanded international cohort of cosmetic talc miners and millers — G.M. Marsh, A.M. Ierardi (2020)
• Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period — G.M. Marsh, A.M. Ierardi, et al. (2019)
• Mortality of Talc Miners and Millers From Val Chisone, Northern Italy: An Updated Cohort Study — E. Pira, M. Coggiola, et al. (2017)
• Evaluation of respiratory effects in miners and millers exposed to talc free of asbestos and silica — D.H. Wegman, J.M. Peters, et al. (1982)
• 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)
• Mortality in the cohort of talc miners and millers from Val Chisone, Northern Italy: 74 years of follow-up — C. Ciocan, E. Pira, et al. (2022)

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