May 14, 2007 in Nation/World

Chemicals linked to animal breast cancer

Marla Cone Los Angeles Times

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Washington Post

More than 200 chemicals – many found in urban air and everyday consumer products – cause breast cancer in animal tests, according to a compilation of scientific reports published today.

Writing in a publication of the American Cancer Society, researchers concluded that reducing exposure to the compounds could prevent many women from developing the disease. The research team analyzed a growing body of evidence that linked environmental contaminants to breast cancer, the leading killer of U.S. women in their late 30s to early 50s.

Experts say that family history and genes are responsible for a small percentage of breast cancer cases but that environmental or lifestyle factors such as diet are probably involved in the vast majority.

The scientists said data were too incomplete to estimate how many breast cancer cases might be linked to chemical exposures.

Reviewing hundreds of existing studies and databases, the team produced what it called “the most comprehensive compilation to date of chemicals identified as mammary carcinogens.”

They named 216 chemicals that induce breast tumors in animals. Of those, people are highly exposed to 97, including industrial solvents, pesticides, dyes, gasoline and diesel exhaust compounds, cosmetics ingredients, hormones, pharmaceuticals, radiation and a chemical in chlorinated drinking water.

Toxicologists say that other mammals, such as rats and mice, often develop the same tumors as humans do, and that animal tests are efficient means of testing the effects of chemicals. Environmental regulators, however, often want conclusive human data before taking action.

Twenty-nine of the breast carcinogens are produced in volumes exceeding 1 million pounds annually in the United States. Seventy-three are in consumer products, such as 1,4-dioxane in shampoos, or are food contaminants, such as acrylamide in French fries. Thirty-five are common air pollutants, 25 are in work places where at least 5,000 women are employed, and 10 are food additives, according to the reports.

The three reports and a commentary were compiled by researchers from the Silent Spring Institute, a women’s environmental health institute in Newton, Mass.; Harvard’s Medical School and School of Public Health in Boston; the Roswell Park Cancer Institute in Buffalo, N.Y.; and the Keck School of Medicine at the University of Southern California.

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