Use of hair dyes may increase risk for breast cancer among certain women, new research suggests.

Specifically, dark brown or black hair dye was associated with a 51 percent increased overall risk of developing breast cancer among African American women, and a 72 percent increased risk of estrogen receptor positive breast cancer among African Americans. What’s more, the use of chemical relaxers or straighteners was associated with a 74 percent increased risk among Caucasians, with some differences in breast cancer risk observed by estrogen receptor status.

The research appears in the June 2017 online issue of Carcinogenesis.

The study included 4,285 African American and Caucasian women with breast cancer cases and controls aged 20 to 75 who were recruited from New York City and ten New Jersey counties through 2014 and were participants in the Women’s Circle of Health Study were analyzed. The New Jersey State Cancer Registry was involved in identification of breast cancer cases in New Jersey. Researchers collected socio-demographics and established probable breast cancer risk factors, including: family and personal health history, prenatal exposures, reproductive history and hormone use, and lifestyle exposures (e.g., hair product use, tobacco smoke exposure, alcohol consumption, physical activity, vitamin use) from all participants. They also collected breast tumor characteristics from all breast cancer patients in the study.

Although more research is needed to prove any cause-effect relationship, these novel findings provide support of a relationship between the use of some hair products and breast cancer risk, conclude researchers from Rutgers University, Roswell Park Cancer Institute, Massachusetts General Hospital and Moffitt Cancer Center.  “Our findings highlight the need for further examinations of the link between the use of hair products as important exposures that may contribute to the development of breast cancer, as well as ways to reduce the associated risks.”