A quantitative weight of evidence assessment of Hill's guidelines for causal inference for cosmetic talc as a cause of mesothelioma

Highlights: • Cosmetic talcum powder product use is alleged to increase mesothelioma risk. • Multi-disciplinary evidence was quantitatively assessed using Hill's guidelines. • A 1.29% causal probability was calculated for cosmetic talc and mesothelioma. Cosmetic talc has been suggested to cause mesothelioma. To assess a potential causal relationship between cosmetic talc and mesothelioma, a quantitative weight of evidence analysis was performed in accordance with Hill's nine original guidelines for causal inference using a published empirical model to weight each respective guideline. Various epidemiological, toxicological, and exposure studies related to cosmetic talc and risk of mesothelioma were included in an evaluation of each of Hill's guidelines. Probabilities that the guidelines were true were assigned based on expert judgment. We applied a sensitivity analysis to evaluate the variability of our probability estimates. The overall probability of causality for cosmetic talc and mesothelioma was approximately 1.29% (range: 0.73%–3.96%). This low probability of causality supports the conclusion that cosmetic talc is not related to the development of mesothelioma.