Study: Northeast's Higher Breast Cancer Rate Not Related to PCBs, DDT

A higher rate of breast cancer in the northeastern U.S. may not be the result of industrial chemicals, according to researchers Brigham and Women's Hospital and Harvard Medical School in Boston.

Scientists have speculated that PCBs and DDT might be responsible for the high breast cancer rates in the northeastern U.S., where death rates among women older than 50 have been reported to be as much as 50 percent higher than those of women living in the south.

DDT and PCBs, which can accumulate in fatty tissue and blood, were banned in the 1970s and studies have shown that the chemicals mimic the effects of estrogen by stimulating the growth of precancerous and cancerous breast cells in a laboratory setting.

Researchers analyzed five studies including 1,400 patients with breast cancer and more than 1,600 cancer-free people living in New York, Maryland and Connecticut, and found no link between DDT and PCBs and breast cancer, according to the study published in the Journal of the National Cancer Institute.

"The majority of the studies published to date do not support the hypothesis that elevated exposure to DDT and PCBs increases the risk of breast cancer," said the study.

Other sources: Journal of the National Cancer Institute, Reuters