Although the United States and Europe banned DDT more than three decades ago, the pesticide lingers in the environmentand in some women's bodies. Toxicologist Corinne Charlier of the Sart Tilman Hospital in Liège, Belgium, and her colleagues recently found that women with breast cancer were five times more likely than healthy women to have DDT residues in their blood.
Previous studies have shown that chemicals derived from DDT can mimic the action of estrogen and related hormones. Excess estrogen promotes breast cancer. Charlier's study of 159 women suggests that traces of DDT carry the same risk. "If it does, it is only one factor, like a genetic mutation. In some women, the pesticide might induce breast cancer, but in other women, it alone is not sufficient," she says. The pesticide remains in the food chain because it can persist in the soil for decades and will eventually turn up in fish and grains. It is still used in developing countries, where it poses a threat not only to the local population but also to people who buy products from those countries.