On April 2, 2024, Critical Reviews in Toxicology published an article titled “A systematic review of the epidemiology evidence on talc and cancer.” The article presents a comprehensive review of epidemiological studies examining whether occupational or personal exposure to talc is associated with cancer risk. According to the authors, the review applies a consistent analytical framework across a broad body of published research and evaluates whether the available epidemiological evidence supports a causal association between talc exposure and cancer.
Background
The article reviewed previously published epidemiological studies evaluating potential associations between talc exposure and the development of various cancers. The studies included cohort and case-control studies, as well as pooled analyses conducted across multiple countries over several decades. The stated objective of the review was to assess whether talc may be considered a human carcinogen by applying uniform evaluation criteria to existing epidemiological evidence.
Study Methods
The authors conducted a literature search identifying relevant studies published through January 23, 2024. From each study, the following information was extracted: author and year of publication; study design; study population characteristics; sources of cohorts, cases, and controls; sample size; exposure characteristics; and outcomes assessed, including cancer type, incidence or mortality, and follow-up period.
Each study was evaluated for methodological quality to assess the reliability of its findings. The authors noted that direct measurements of talc exposure were rarely available in either occupational or personal-use studies, resulting in variability in exposure assessment methods. The review observed that certain approaches, such as job exposure matrices developed by industrial hygienists with relevant experience, were generally more robust than self-reported exposure histories.
Results and Analysis
The evidence from the reviewed studies was synthesized by cancer type. For most cancer types, the authors reported no observed association between talc exposure and cancer. In some instances, the evidence was considered insufficient to draw conclusions.
For cancer types with mixed results or suggestive of a possible association, including ovarian, respiratory, and upper gastrointestinal tract cancers, the authors evaluated the plausibility of causation using the Bradford Hill criteria. These criteria are commonly applied in epidemiology to assess whether an observed association is likely to be causal and include considerations such as strength and consistency of association, temporality, dose-response, biological plausibility, and coherence.
Ovarian Cancer
Applying the Bradford Hill criteria, the authors concluded that the evidence did not support a causal association between talc exposure and ovarian cancer. Meta-analyses of prospective cohort studies did not demonstrate an association. Some meta-analyses of case-control studies reported small positive associations; however, the authors noted that these findings were difficult to interpret due to potential biases in the underlying studies, including recall bias.
Respiratory Cancers
Several epidemiological studies examined associations between talc exposure and respiratory cancers, including lung cancer and mesothelioma. The review noted that none of the analyzed studies reported an increased risk of mesothelioma. The authors also observed that many studies lacked direct exposure measurements and did not consistently control for smoking, a known confounding factor. Based on these considerations, the authors concluded that the epidemiological evidence does not support a causal relationship between talc exposure and respiratory cancers.
Upper Gastrointestinal Tract Cancers
The review identified studies evaluating cancers of the oral cavity, pharynx, esophagus, and stomach, with mixed findings. The authors assessed this evidence collectively using the Bradford Hill framework. One meta-analysis (Chang et al., 2018) reported an increased risk of stomach cancer associated with talc exposure, though risks observed in talc-using industries were not statistically significant. The authors concluded that, given inconsistent results, lack of direct exposure measurements, and limited control for confounding factors such as smoking and alcohol consumption, the available evidence does not support talc as a causal factor in upper gastrointestinal tract cancers.
Conclusion
According to the authors, this systematic review evaluated epidemiological evidence on talc exposure across occupational, medicinal, and personal care product use, as well as across multiple cancer types. After applying consistent evaluation criteria to 77 published studies, the authors concluded that the available epidemiological evidence does not establish a causal association between talc exposure and cancer in humans.
About the Authors
The study was authored by Dr. Julie E. Goodman and Dr. Robyn L. Prueitt. Dr. Goodman is an epidemiologist and board-certified toxicologist with more than 20 years of experience and holds a Ph.D. in Toxicology from Johns Hopkins University. Dr. Prueitt holds a Ph.D. in Cell and Molecular Biology/Human Genetics from the University of Texas Southwestern Medical Center and has expertise in toxicology, carcinogenesis, human genetics, and human health risk assessment. The publication discloses the authors’ prior professional work in accordance with journal disclosure requirements.
The authors have published additional peer-reviewed articles on talc and cancer, including work in the Journal of Toxicology and Environmental Health, Part B, and Critical Reviews in Toxicology.
For questions regarding how the findings discussed above may relate to your organization, please contact your GRSM attorney or the authors of this legal alert.