Letter to the Editor: Misrepresentation by Egilman et al. of the Fordyce et al. (2019) Vermont Talc Miners and Millers Cohort Study Update

Exposure to cosmetic talc and mesothelioma

AIM

Mesothelioma is associated with asbestos exposure. In this case series, we present 166 cases of individuals who had substantial asbestos exposure to cosmetic talc products as well as some who had potential or documented additional exposures to other asbestos-containing products and who subsequently developed mesothelioma.

METHODS

Data were gathered for all subjects referred to an occupational and environmental medicine specialist as part of medicolegal review. Years of total cosmetic talcum powder usage was noted as well as the latency from the onset of talcum powder use to the mesothelioma diagnosis. Alternate asbestos exposure in addition to the exposure from cosmetic talc was categorized as none, possible, likely, and definite.

RESULTS

In 122 cases, the only known exposure to asbestos was from cosmetic talc. For 44 cases, potential or documented alternate exposures in addition to the cosmetic talc were described.

CONCLUSION

Cumulative exposure to asbestos leads to mesothelioma; for individuals with mixed exposures to asbestos, all exposures should be considered. Use of cosmetic talc is often overlooked as a source of asbestos exposure. All individuals with mesothelioma should have a comprehensive history of asbestos exposure, including cosmetic talc exposure.

Updated Italian cohort data continues to confirm lack of mesothelioma risk in pooled cohort of international cosmetic talc miners and millers

OBJECTIVES

To assess potential mesothelioma risk following inhalation of cosmetic talc, we updated previous iterations of a pooled cohort analysis, post-study statistical power analysis, and confidence interval function analysis for a pooled cohort of international cosmetic talc miners/millers given new Italian cohort data.

METHODS

Five cohorts of cosmetic talc miners/millers were pooled. Expected numbers of mesotheliomas for each cohort were reported by the original authors. We based our post-study statistical power analysis on an a priori one-sided significance level of 0.05, and exact Poisson and approximate distribution probabilities. To evaluate the confidence interval function for the observed pooled mesothelioma standardized mortality ratios (SMRs), we calculated the probability for the upper 100(1-2α)% confidence limit that equals various SMRs of interest.

RESULTS

The pooled cohorts generated a total observation time of 135,524.38 person-years. Overall, 4.14 mesotheliomas were expected (mid-value estimate), though only one case of mesothelioma has been confirmed in the pooled cohort to date. We calculated 71% and 87% post-study power to detect a 2.5-fold or greater and a 3.0-fold or greater increase in mesothelioma, respectively. Our complimentary confidence interval function analysis demonstrated that the probability that the true mesothelioma SMR for the pooled cohort was at or above 2.0 or at or above 3.0 was 0.00235 and 0.00005, respectively.

CONCLUSIONS

Based on the updated results of our various analyses, the current epidemiological evidence from cosmetic talc miner/miller cohort studies continues to not support the hypothesis that the inhalation of cosmetic talc is associated with an increased risk of mesothelioma.