Confidence interval function analysis to evaluate the risk of mesothelioma among an expanded international cohort of cosmetic talc miners and millers

Our plain-English summary of Confidence interval function analysis to evaluate the risk of mesothelioma among an expanded international cohort of cosmetic talc miners and millers, by G.M. Marsh, A.M. Ierardi (Regulatory Toxicology and Pharmacology, 2020).

The study

• Authors: G.M. Marsh, A.M. Ierardi
• Journal: Regulatory Toxicology and Pharmacology
• Published: 2020;115:104696
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We used pooled data from international cosmetic talc miner/miller cohorts to determine whether hypothesized increased mesothelioma risks are consistent with the observed data. We evaluated the confidence interval function for the observed pooled mesothelioma SMRs (observed = 1; expected = 3.17, 3.34, or 3.60), and calculated the value of α for the upper 100(1 - 2α)% confidence limit that equals various SMRs of interest (1.5, 2.0, 2.5, 3.0). Using the mid-value estimate of expected number of cases (3.34), the probability (α) that the true mesothelioma SMR is at or above 2.0, or at or above 3.0 is 0.0096 and 0.0005, respectively. Thus, a mesothelioma SMR ≥2.0 is not compatible with the observed pooled data, providing further support for our conclusion that cosmetic talc exposure is not associated with an elevated risk of mesothelioma.

Copyright © 2020 Elsevier Inc. All rights reserved.

In plain English

This paper was a statistical reanalysis of published data, not a new study of workers. The authors pooled five cohorts of cosmetic talc miners and millers (Italy, Norway, France, Austria and Vermont; 130,514 person-years). In these cohorts one mesothelioma death was observed, in the Vermont cohort, against an estimated 3.17, 3.34 or 3.60 expected. With the middle estimate, the standardized mortality ratio (SMR) was 0.299, with limits of 0.015 to 1.42. The article calls this a 95% confidence interval in places, but its own table and appendix compute it as a 90% interval. Using a 'confidence interval function' method and 3.34 expected cases, the authors estimated the probability that the true SMR was 2.0 or higher at 0.0096, and 3.0 or higher at 0.0005. Probabilities were also very low with the other two estimates. The authors noted that the cohorts used different disease-coding systems to identify mesothelioma deaths. They concluded that a true SMR of 2.0 or greater was very unlikely, which they said further supported their conclusion that cosmetic talc exposure is not associated with an elevated risk of mesothelioma.

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: Statistical reanalysis (confidence interval function analysis) of pooled, previously published cohort mortality data, extending the authors' earlier post-study power analyses
• Who was studied: Five pooled cohorts of cosmetic talc miners and millers from Italy, Norway, France, Austria and Vermont, totaling 130,514 person-years of observation
• Exposure: Occupational exposure to cosmetic talc during mining and milling. The authors described these exposures as more prolonged and intense than consumer use. No exposure or fiber measurements were made in this paper.
• Main results:
  • Across the pooled cohorts, one mesothelioma case (in the Vermont cohort) was observed. Total expected cases were estimated at 3.17, 3.34 or 3.60, depending on the Vermont estimate used.
  • Using the mid-value of 3.34 expected cases, the pooled mesothelioma SMR was 0.299, with limits of 0.015 to 1.42 (labeled 95% CI here; computed as the 90% interval in Table 2 and the appendix)
  • With 3.34 expected cases, the estimated probability that the true mesothelioma SMR was at or above 2.0 was 0.0096, and at or above 3.0 was 0.0005
  • Very low probabilities of 2.0- or 3.0-fold elevations were also found with the smallest (3.17) and largest (3.60) estimates of expected cases
  • By exact post-study power analysis (3.34 expected cases), the pooled studies had a 35%, 59% or 78% chance of producing a statistically significant SMR of 2.0, 2.5 or 3.0, respectively
• The authors' conclusion: The authors concluded that a true mesothelioma SMR of 2.0 or greater for the pooled cohorts is very unlikely. They said this further supports their conclusion that exposure to cosmetic talc is not associated with an elevated risk of mesothelioma.
• Limitations the authors state:
  • The pooled cohort studies used different International Classification of Disease code versions to identify mesothelioma deaths

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: confidence interval, Mesothelioma, Cosmetic Talc.

Related studies

• Absence of mesothelioma risk maintained in an expanded international cohort of cosmetic talc miners and millers — A.M. Ierardi, G.M. Marsh (2020)
• Mortality of Talc Miners and Millers From Val Chisone, Northern Italy: An Updated Cohort Study — E. Pira, M. Coggiola, et al. (2017)
• 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 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)
• Malignant mesothelioma incidence among talc miners and millers in New York State — M.M. Finkelstein (2012)
• 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)

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