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Research Effort May Guide Regulation of Chemicals Linked to Breast Cancer

SAN DIEGO—An expert panel of researchers working with California's "green chemistry" initiative will release a report this spring that could help the state decide on stricter regulations for synthetic chemicals linked to some breast cancers, speakers said at the AAAS Annual Meeting.

Dioxin, bisphenol A, and similar chemicals can damage breast tissue, according to some reports, and a few studies have found higher rates of breast cancer among women exposed to high levels of these agents. But it's still unclear how the chemicals might trigger cancers, the scientists said, and which chemicals are the most toxic and should be regulated immediately.

"We lack hazard information on tens of thousands of chemicals that are in common use in the United States," said Megan Schwarzman, co-director of the California Breast Cancer and Chemicals Policy Project, who noted that more than 34 million metric tons of chemical products are produced or imported into the U.S. each day.

Under federal law, chemical producers don't have to release basic information about the use or potential health effects of their products, and chemicals stay on the market until regulators can prove that they are harmful, said Schwarzman, an environmental health researcher at the University of California, Berkeley.

The current system places the burden of risk on consumers, she said. "And you shouldn't have to have an advanced chemistry degree when you go to the grocery store."

The incidence of breast cancer in the U.S. "has skyrocketed," said Sarah Janssen, the project's co-director and staff scientist at the National Resources Defense Council. Breast cancer now affects one in eight women compared to one in 20 women a generation ago. Environmental factors--including a world awash in synthetic chemicals--may be behind the rise, Janssen said, since genetic changes happen too slowly to bring about such a dramatic trend.

The researchers are examining "critical windows" of breast tissue development, to find out when and how chemicals might prompt the development of cancer. Breast cancer "can take years to develop," said Suzanne Fenton, a researcher at the National Institute of Environmental Health, which may mean that some cancers have their roots in early toxic exposures.

At the same time, scientists need to know more about exactly which chemicals have the potential to be toxic for breast cells. Some agents that mimic the actions of estrogen are known to cause cancer, according to California Environmental Protection Agency scientist Lauren Zeise. But she warned that there are many other chemically-driven pathways to cancer, and it can be difficult to test for these pathways when "we are exposed to any particular agent in a sea of chemicals."

Recent regulatory changes in the European Union, which require the chemical industry to disclose more of the properties and hazards of their products, could result in a flood of new data to help solve some of these problems, the panelists agreed.