Researchers have found that 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. The study, published in the International Journal of Cancer, suggests that breast cancer risk increased with more frequent use of these chemical hair products.

"Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent," said study author Alexandra White from the National Institute of Environmental Health Sciences (NIEHS) in the US.