MARLA  CONE, LA TIMES - 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. . . 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.
"Overall, exposure to mammary  gland carcinogens is widespread," the researchers wrote in a special supplement  to the journal Cancer. "These compounds are widely detected in human tissues and  in environments, such as homes, where women spend time.". . . 
The  researchers 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  chemicals are produced in volumes exceeding 1 million pounds annually in the  United States. Seventy-three are present in consumer products or are food  contaminants - 1,4-dioxane in shampoos, for example, or acrylamide in French  fries. Thirty-five are common air pollutants, 25 are in workplaces where at  least 5,000 women are employed, and 10 are food additives, according to the  reports.