Study reveals more about DDT exposure's association with breast cancer risk

Exposure to dichlorodiphenyltrichloroethane (DDT) puts women at an increased risk of breast cancer through the age of 54, according to research published by the Journal of the National Cancer Institute.

DDT was commonly used as an insecticide before its agricultural use was banned in the United States in 1972. Prior research had determined that DDT exposure was associated with a significantly increased risk of premenopausal breast cancer for women first exposed to the chemical compound before puberty. The focus on this study, led by co-author Barbara A. Cohn, PhD, of Child Health and Development Studies (CHDS), was on women between the ages of 50 and 54.

The authors explored CHDS data from 153 breast cancer cases diagnosed at ages 50-54. The patients had all received obstetric care in the San Francisco East Bay area from 1959 to 1967. Surveillance of CHDS participants has continued to this day though the California Department of Motor Vehicles, California Department of Vital Statistics and California Cancer Registry.

Overall, the team found that DDT exposure was associated with an increased risk of postmenopausal breast cancer for all women, including women first exposed to DDT after infancy. This was different from the team’s research into premenopausal patients, when the association with an increased breast cancer risk was strongest for women exposed to DDT in utero or in their infancy.

“Risk depended on timing of first exposure and diagnosis age, suggesting susceptibility windows and an induction period beginning in early life,” the authors wrote. “DDT appears to be an endocrine disruptor with responsive breast targets from in utero to menopause.”