Katherine Reeves Lends Expertise to International Agency for Research on Cancer

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Katherine Reeves and the IARC Monographs working group in Lyon, France

Professor of Epidemiology Katherine Reeves traveled to Lyon, France, in June to join a working group for the International Agency for Research on Cancer (IARC), the specialized cancer agency of the World Health Organization. 

The team looked at studies on the carcinogenicity of three chemicals: butyl benzyl phthalate, dibutyl phthalate and diisononyl phthalate, substances common in everyday items ranging from PVC and cable coatings to dust and personal care products. Worldwide studies have clearly demonstrated ubiquitous exposure to the chemicals among the general population, with more regular occupational exposure occurring among workers involved in automobile, PVC film and plastic manufacturing and processing, and recycling activities, as well as service-based occupations such as nail salon workers and health-care workers.

Reeves was a member of the working group of 23 scientists from 13 countries who met to finalize their evaluation for the latest IARC Monograph. Their findings, reported in The Lancet, indicated that these chemicals are “possibly carcinogenic,” based on “strong” mechanistic evidence in experimental systems, but more research is needed regarding their impact on humans.

“There is definitely support from these laboratory studies and these animal studies that these agents can act in ways that we know can be carcinogenic,” Reeves said. “However, the study in humans is insufficient. And so, there's an opportunity for future research to hopefully give more information within humans as to whether or not these agents are carcinogens.”

Many of the human studies focused on any connection between phthalates and breast cancer, but the small number of these studies limits drawing conclusions, Reeves said.

For nearly 50 years, the IARC Monographs program has been a premier global resource for identifying agents that can cause cancer. The identification of carcinogenic hazards is a necessary initial step in cancer prevention. National and international authorities and organizations use information on causes of cancer to support actions to reduce human exposure to carcinogens. More than 1000 agents have been evaluated to date in the Monographs program.

“I think the work we did was incredibly important and very thorough and thoughtful, and people really worked hard to evaluate these agents in a way that was fair and rigorous,” she said. “Just as a scientist, it was a great experience to be able to be part of that process.”