Women who regularly use permanent hair dyes or chemicals to relax and straighten their hair may have an increased risk of breast cancer, according to a new study published in the International Journal of Cancer. The heightened risk especially affects African American women, according to researchers.
For the study, researchers from the National Institute of Environmental Health Sciences used data from 46,709 women from the ongoing Sister Study. While the researchers found little to no increase in breast cancer risk associated with semi-permanent or temporary dye use, they did find that women who regularly used permanent hair dye in the year prior to enrolling in the study were 9% more likely to develop breast cancer than women who did not use these products.
Among African American women, though, the risk was significantly higher: Using permanent dyes every couple of months or more frequently was associated with a 60% increased risk of breast cancer as compared to an 8% increased risk for white women.
Additionally, women who used chemical hair straighteners at least every five to eight weeks were about 30% more likely to develop breast cancer. The association between straightener use and breast cancer was similar among races, but straightener use was more common among African American women, with about 75% of black women in the study reporting that they use chemical straighteners.
“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, head of the NIEHS Environment and Cancer Epidemiology Group in a news release. “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.”
Hair dye is very common in the United States, with an estimated one-third of women above 18 using the product, according to the study. Hair products can also contain thousands of chemicals, including some, like aromatic amines, that have endocrine-disrupting properties, White told NPR.
So, should women stop using chemical hair dyes and straighteners?
The study’s co-author, Dale Sandler, chief of the NIEHS Epidemiology Branch, says more research still needs to be done.
“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,” Sandler said in the news release. “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.”
Does this study give you pause about using chemical hair dyes or straighteners?