A coalition of members of Congress, health professionals, and women’s advocates yesterday sent a letter to Pres. Clinton demanding more money for research into potential environmental causes of breast cancer. The group wants further research into factors that might increase risk for the disease, including exposure to some fuels, plastics, detergents, pesticides, and pharmaceutical drugs. Such research could home in on synthetic substances that mimic the behavior of estrogen in breast tissue, the group said. “We’ve identified 200 man-made chemicals so far that we are carrying in our breasts and our breast milk and passing on to our children. Are our breasts becoming reservoirs for toxics?” asked Andrea Martin, a coalition member and breast cancer survivor.