Eberle CE, et al. - Among participants (n = 46,709) from Sister Study (women ages 35–74) who had a sister with breast cancer but were breast cancer-free themselves, researchers assessed the link between hair dye and chemical relaxer/straightener use and breast cancer risk by ethnicity in this national prospective cohort investigation. They inquired about past 12-month hair product use via enrollment questionnaires. Participants were observed for a mean duration of 8.3 years, during which, 2,794 breast cancers were found. In relation to permanent dye use, they found 45% higher breast cancer risk in black women and a 7% higher risk in white women. Overall, any straightener use and personal use of permanent dye was related to a higher breast cancer risk, particularly among black women. In breast carcinogenesis, a possible role of chemicals in hair products was suggested.