Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period

Our plain-English summary of Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period, by G.M. Marsh, A.M. Ierardi, S.M. Benson, et al (Inhalation Toxicology, 2019).

The study

• Authors: G.M. Marsh, A.M. Ierardi, S.M. Benson, B.L. Finley
• Journal: Inhalation Toxicology
• Published: 2019;31(6):213-223
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: We previously published a pooled statistical power analysis of mesothelioma incidence in the Italian, Norwegian, Austrian, and French cosmetic talc miner and miller cohorts. Soon thereafter, updates to the Italian and Norwegian cohorts were published, providing an additional 14,322 person-years of observation. In this study, we provide an updated power analysis using the newly available information. Methods: We pooled the current results regarding pleural cancer/mesothelioma mortality or incidence in four cosmetic talc miner and miller cohorts in Italy, Norway, Austria, and France. We used the expected numbers of cases as reported by the authors and the power analysis was based on an a priori one-sided significance level of 0.05 and Poisson distribution probabilities. Results: There was a pooled total of 113,344 person-years in the cohorts. Although 3.0 pleural cancers/mesotheliomas were expected, there were no reported pleural cancer or mesothelioma cases in any cohort. Our pooled analysis was associated with 79 and 62% power to detect a 3.0-fold and 2.5-fold or greater increase in pleural cancer/mesothelioma, respectively. These favorable power characteristics were effectively maintained when restricting the pooled cohort to workers with a latency period of 30 or more years (observation time from first employment). Conclusions: The epidemiological evidence from the cosmetic talc miner/miller cohort studies does not support the hypothesis that exposure to cosmetic talc is associated with the development of pleural cancer/mesothelioma.

In plain English

This paper pooled published results from four cohorts of cosmetic talc miners and millers in Italy, Norway, France and Austria. It updated the authors' 2017 analysis using newer Italian and Norwegian follow-up. The main analysis reused published cohort results rather than new follow-up, though the authors also obtained causes of death for 115 excluded Italian workers; none had died of mesothelioma. It used the expected case numbers reported by the original authors to calculate statistical power. Across 113,344 person-years, 3.0 cases were expected and none were confirmed. The authors calculated 79% power to detect a 3.0-fold or greater increase, 62% for 2.5-fold, and 17% for 1.5-fold. Seven or more cases would have been needed to show a statistically significant excess. Workers 30 or more years past first employment contributed 36.3% of person-years but 97.9% of expected cases; the authors said power was effectively maintained in that group. The authors concluded the evidence does not support an association between cosmetic talc exposure and pleural mesothelioma. They noted they had to estimate some person-years, used national rates, and assumed hiring at age 20 to 29.

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 analysis of previously published cohort studies, with a statistical power calculation (one-sided 5% significance test, exact Poisson probabilities) and a latency analysis. No new cohort follow-up was done, though the authors obtained supplementary cause-of-death data for 115 excluded Italian workers and used WHO mortality and population data.
• Who was studied: Cosmetic talc miners and millers in four published cohorts. Italy (Pira et al. 2017): 1166 miners and 556 millers, 59,339 person-years. Norway (Wergeland et al. 2017): 94 miners and 296 millers, 15,687 person-years. France (Wild et al. 2002): 1070 miners and millers, 28,849 person-years. Austria (Wild et al. 2002): 542 miners and millers, 9469 person-years. Pooled total 113,344 person-years; the latency table prints 113,345.
• Exposure: Occupational exposure to cosmetic talc through mining and milling; exposure levels and asbestos content were not measured in this analysis
• Main results:
  • No pleural cancers or mesotheliomas were confirmed in any of the four cohorts.
  • The pooled expected number was 3.0 pleural cancers/mesotheliomas: Italy 2.0, Norway 0.6, France 0.3 and Austria 0.1. The authors called 3.0 a lower limit because the French and Austrian figures were for mesothelioma only.
  • With 3.0 expected cases, the pooled analysis had 79% power to detect a 3.0-fold or greater increase and 62% power to detect a 2.5-fold or greater increase. The earlier 2017 analysis, with 4.0 expected cases, gave 84% and 67%.
  • Power to detect a 1.5-fold increase was 17%, and to detect a 2.0-fold increase was 39% (Table 2, 3 expected cases).
  • With 3.0 expected cases, 7 or more observed cases would have been needed to reject, at the 0.05 level, the hypothesis of no association.
  • Workers with 30 or more years since first employment contributed 41,133 person-years (36.3% of the total) but 2.77 (97.9%) of the 2.82 expected mesotheliomas in the latency analysis. The authors said power was effectively maintained in this subgroup.
  • The authors obtained causes of death for 115 Italian cohort members excluded by Pira et al. (2017) for being 85 or older at death; none died of mesothelioma (personal communication).
  • In a sensitivity calculation, two claimed but unverified cases (one linked to the Italian mine, one to a Vermont talc cohort) were counted. This gave 2 observed against 3.0 expected, an SMR of 0.66 (95% CI 0.08 to 2.41).
• The authors' conclusion: The authors concluded that the current epidemiological evidence does not support a hypothesis that exposure to cosmetic talc is associated with the development of pleural mesothelioma.
• Limitations the authors state:
  • For the latency analysis, person-years for workers with 30 or more years since first employment had to be estimated for the Norwegian, French and Austrian cohorts, because those studies did not report them.
  • The latency analysis used national rather than regional age-specific mesothelioma rates, because regional rates were unavailable.
  • The latency analysis assumed that every cohort member was hired at age 20 to 29.

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: Occupational Exposure, Cosmetic Talc, Mesothelioma, Latency, Meta-Analysis.

Related studies

• 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)
• Absence of mesothelioma risk maintained in an expanded international cohort of cosmetic talc miners and millers — A.M. Ierardi, G.M. Marsh (2020)
• 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)
• 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 of Talc Miners and Millers From Val Chisone, Northern Italy: An Updated Cohort Study — E. Pira, M. Coggiola, et al. (2017)
• Occupational Exposure to Talc Increases the Risk of Lung Cancer: A Meta-Analysis of Occupational Cohort Studies — C.J. Chang, Y.K. Tu, et al. (2017)

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