Study: Hair Dye, Chemical Straighteners May Increase Breast Cancer Risk

BOSTON (CBS) -- More than a third of women dye their hair and a new study from the National Institutes of Health (NIH) finds that regular use of these chemicals could put women at higher risk of breast cancer.

There has been concern that hair dye might promote cancer for some time but the data has been conflicting.

In this NIH study, researchers looked at data on more than 46,000 women whose sisters had been diagnosed with breast cancer.

They found that those who regularly used permanent hair dye were 9% more likely to develop breast cancer and those who regularly used chemical hair straighteners were 30% more likely to develop breast cancer than women who didn't use those products. The effect was considerably stronger in black women than white women.

Does this mean women should stop dyeing or straightening their hair? There's probably still not enough evidence to make that recommendation, but women, especially those at higher risk of breast cancer, may want to limit their use to minimize any potential harm.