Permanent hair dye, straighteners may increase breast cancer risk, NIH study suggests

Women who use permanent hair dye and chemical hair straighteners could have a higher risk of developing breast cancer, scientists at the National Institutes of Health found in a study published Wednesday. 

The study, published in the International Journal of Cancer, suggests that breast cancer risk increased with more frequent use of the chemical hair products, according to an NIH press release

"Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent," said corresponding author Alexandra White, Ph.D., head of the NIEHS Environment and Cancer Epidemiology Group. "In our study, we see a higher breast cancer risk associated with hair dye use, and the effect is stronger in African American women, particularly those who are frequent users."

FILE: A woman had her hair cut and colored at a beauty salon in Santa Monica, California on March 18, 2015.

Researchers at the National Institute of Environmental Health Sciences (NIEHS), which is part of NIH, used data from 46,709 women in the Sister Study and found that women who regularly used permanent hair dye in the year prior to enrolling in the study were 9 percent more likely to develop breast cancer than women who didn’t use hair dye. 

Among African American women, using permanent dyes every five to eight weeks or more was associated with a 60 percent increased risk of breast cancer, compared with an 8 percent increased risk for white women, according to the NIH release. 

The research team found little to no increase in breast cancer risk for semi-permanent or temporary dye use.

“An intriguing finding was the association between the use of chemical hair straighteners and breast cancer,” the NIH release said. 

White and colleagues found that women who used hair straighteners at least every five to eight weeks were about 30 percent more likely to develop breast cancer. While the association between straightener use and breast cancer was similar in African American and white women, straightener use was much more common among African American women, researchers found. 

Co-author Dale Sandler, Ph.D., chief of the NIEHS Epidemiology Branch, cautioned that although there is some prior evidence to support the association with chemical straighteners, the results need to be replicated in other studies.

"We are exposed to many things that could potentially contribute to breast cancer, and it is unlikely that any single factor explains a woman’s risk. While it is too early to make a firm recommendation, avoiding these chemicals might be one more thing women can do to reduce their risk of breast cancer," Sandler said when asked if women should stop dyeing or straightening their hair.