Q & A Library

You may be referring to a report issued in March 2008 by the Breast Cancer Fund, a nonprofit group that believes that the upswing in breast cancer in the United States since World War II is linked to the growing number of synthetic chemicals in use as well as to increased radiation exposure. The report, which offers no new evidence, estimates that more than 80,000 chemicals are in use with another 1,000 or so being introduced every year.

Although the group recognizes the recently reported drop in breast cancer incidence, attributed mainly to declining use of hormone replacement therapy, it maintains that data linking radiation and environmental chemicals to breast cancer are "compelling." And it suggests that a critical factor in breast cancer risk may be exposure to endocrine-disrupting chemicals during childhood, adolescence and in the womb.

Rates of other diseases have also been rising with increased exposure to many of the chemicals discussed in the report, including birth defects and developmental disorders, childhood cancers, and asthma. Again, we have no proof of a causal relationship, just worrisome coincidence.

We have no conclusive evidence that environmental chemicals are responsible for the increase in breast cancer, either - although those 400-plus studies cited in the report testify to the fact that researchers suspect a connection and have been looking for a link. (Obesity, a recognized risk factor for breast cancer, also has risen markedly in the same time period.)

We may never know for sure exactly what causes breast cancer. I discussed this report with Ruby Senie, Ph.D., a breast cancer epidemiologist at Columbia University in New York. Given the huge number of synthetic chemicals to which we are likely exposed "in combinations too numerous to imagine," Dr. Senie says, "There is no way that any epidemiologic study can adequately assess breast cancer risk due to any specific potential carcinogen."

The chemicals won't go away any time soon, so it's up to you to protect your health by eating foods high in antioxidants. Select organic varieties when it comes to foods that tend to have high pesticide residues. (For guidance, check the Web site of the Environmental Working Group at www.ewg.org.) Take a good quality antioxidant multivitamin-mineral every day as insurance against dietary gaps. The long-term solution may be more and better regulation of the chemicals in our environment, but that will come only if we, as citizens, demand it.

Andrew Weil, M.D.