Do Hair Relaxers Cause Breast Cancer?

• Position: BLACK FEMALES

The lifetime risk of developing breast cancer is similar among black and white women in the U.S., but African-American females disproportionately are affected by aggressive breast cancer subtypes, such as estrogen receptor-negative tumors, which often are diagnosed at a younger age and have a higher mortality rate.

Epidemiologists long have wondered about what environmental factors could be at play. One such question has centered on whether chemical hair relaxing products, oils, and leave-in conditioners-more commonly used by black women than white women--may contain compounds with estrogens or endocrine-disrupting chemicals that could influence breast cancer risk. Few studies have investigated the possible link.

"While there is biologic plausibility that exposure to some components contained in hair relaxers might increase breast cancer risk, the evidence from research to date continues to be inconsistent," says Kim-berly Bertrand, assistant professor at Boston University's School of Medicine and an epidemiologist at the Slone Epidemiology Center.

Bertrand and a team of public health researchers analyzed data from the Black Women's Health Study...