Health scare of the week Hair dye and breast cancer

Women who use permanent hair dye and chemical hair straighteners have a higher risk of developing breast cancer, according to a new study by the National Institutes of Health. After examining medical data and lifestyle surveys from 46,709 women ages 35 to 74, researchers found that white women who had used permanent hair dye in the previous year were 7 percent more likely to get breast cancer in the eight-year follow-up period. For black women, the increased risk was 45 percent. Use of chemical hair straighteners was linked to an 18 percent higher breast cancer risk in both black and white women. Researchers don’t know which of the 5,000 chemicals found in hair products might be of concern, or why there is such a racial disparity. It could be that products designed for black women contain more of the cancer-causing chemicals, or that differences in hair texture affect the amounts of dye that are applied. Still, the risk from these products is relatively low—scientists typically worry only when environmental exposures increase cancer risk by 100 percent or more. “These risks are potentially important,” co-author Alexandra White tells The New York Times, “but we know that a lot of different factors contribute to a woman’s risk of breast cancer.”

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