WASHINGTON (CBS Local) -- Women who use permanent hair dye and chemical hair straighteners have a higher risk of developing breast cancer than women who don't use these products, according to a study released on Tuesday.
Researchers with the National Institutes of Health found that women who regularly used permanent hair dye in the year prior to enrolling in the study were 9 percent more likely than who women who didn't use hair dye to develop breast cancer.
The link was particularly evident among African-American women -- their use of permanent dye was associated with 45 percent higher breast cancer risk, while white women faced a 7 percent higher risk.
For heavy use of hair dye -- defined as once or more every five to eight weeks -- the risk increased to 60 percent for black women and 8 percent for white women.
The research team found little to no increase in breast cancer risk for semi-permanent or temporary dye use.
Hair straighteners were associated with 18 percent higher breast cancer risk for African American women while white women faced a 7 percent higher risk, fairly consistent across races.
Women who used the straighteners every five to eight weeks were 31 percent more likely to develop breast cancer.
The study, published online Wednesday in the International Journal of Cancer, used data from 46,709 women in the Sister Study, which recruited breast-cancer-free women whose sisters had been diagnosed with the disease.
Researchers say there's still not enough evidence make a firm recommendation on whether women should stop dying or straightening their hair, but it could be a way to lessen the risk of breast cancer.
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