The International Agency for Research on Cancer (IARC), the World Health Organization’s cancer research arm, has classified talc as “probably carcinogenic” to humans. This announcement has sparked widespread concern, but experts caution against viewing it as definitive proof of a cancer link.
The IARC’s classification is based on “limited evidence” that talc could cause ovarian cancer in humans, “sufficient evidence” of its carcinogenic effects in rats, and “strong mechanistic evidence” showing carcinogenic signs in human cells. The decision, made public on July 5, 2024, highlights the potential risks associated with talc, particularly when used in products like baby powder and cosmetics.
Talc, a naturally occurring mineral mined worldwide, poses the most significant risk during mining, processing, or product manufacturing. The IARC cited numerous studies consistently showing an increased rate of ovarian cancer in women who use talc on their genitals. However, the agency could not rule out the possibility of asbestos contamination in some talc products, which complicates the findings.
Kevin McConway, a statistician at the UK’s Open University, emphasized that the IARC’s evaluation aims to determine whether a substance has the potential to cause cancer under certain conditions. He warned that the observational nature of the studies means causation cannot be conclusively proven, and there isn’t a definitive “smoking gun” linking talc use to increased cancer risk.
This announcement follows closely on the heels of a $700 million settlement by Johnson & Johnson over allegations of misleading customers about the safety of its talcum-based products. Despite the settlement, Johnson & Johnson did not admit wrongdoing and had already withdrawn the product from the North American market in 2020.
Concerns about talc contamination with asbestos date back to the 1970s, with studies indicating a higher risk of ovarian cancer among talcum powder users. However, a comprehensive study in 2020 involving 250,000 women in the United States found no statistical link between genital talc use and ovarian cancer risk.
In addition to the talc classification, the IARC also categorized acrylonitrile, a chemical compound used in making polymers, as “carcinogenic to humans,” citing “sufficient evidence” of its association with lung cancer. Acrylonitrile is used in various consumer products and can be found in cigarette smoke and air pollution.