The WHO agency has stated that talc is “probably” a carcinogen. However, an external expert cautioned against interpreting this classification as definitive proof of harm.
The IARC’s decision to label talc as “probably carcinogenic to humans” was based on “limited evidence” suggesting a potential link to ovarian cancer in humans, along with “sufficient evidence” connecting it to cancer in rats and “strong mechanistic evidence” indicating that it exhibits carcinogenic characteristics in human cells. This information was released on July 5, 2024.
Occupational Exposure
Talc is a naturally occurring mineral mined in various regions worldwide, commonly used in talcum baby powder and cosmetics. The IARC notes that most people encounter talc through these products, but significant exposure typically occurs during mining, processing, or product manufacturing.
The agency cited numerous studies showing a consistent increase in ovarian cancer rates among women who use talc on their genitals. However, it could not definitively rule out the possibility that some talc samples in these studies were contaminated with asbestos, a known carcinogen. The WHO agency has stated that talc is “probably” a carcinogen, but as the IARC’s findings published in The Lancet Oncology indicate, “a causal role for talc could not be fully established.”
Statistician Kevin McConway from the UK’s Open University, who was not involved in the research, warned that the IARC’s classification could be misinterpreted. He pointed out that the agency aims to determine whether a substance may potentially cause cancer under unspecified conditions, rather than conclusively proving such a link. He emphasized that observational studies cannot establish causation, stating, “there isn’t a smoking gun that the talc use causes any increased cancer risk.”
Johnson & Johnson’s Settlement
This announcement coincided with US pharmaceutical and cosmetics giant Johnson & Johnson agreeing to a $700 million settlement over allegations that it misled customers regarding the safety of its talc-based products. Although the company did not admit any wrongdoing in the settlement, it did withdraw the product from the North American market in 2020.
Concerns about talc contamination with asbestos, often found in proximity to talc deposits, emerged in the 1970s, leading to studies that indicated a higher risk of ovarian cancer among users of talcum powder. However, a summary of research conducted in 2020, involving 250,000 women in the United States, found no statistical link between talc use on the genitals and ovarian cancer risk.
Acrylonitrile
On the same day, the IARC also classified acrylonitrile, a chemical used in polymer production, as “carcinogenic to humans,” the highest level of warning. The agency cited “sufficient evidence” linking acrylonitrile to lung cancer. Polymers made with acrylonitrile are found in various products, from clothing fibers and carpets to plastics, and it is also present in cigarette smoke and air pollution.
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