NIH Study Links Hair Dyes, Straighteners To Breast Cancer Risk; Causation Piece Remains Lacking

Analyzing data from around 47,000 women enrolled in its Sister Study, the National Institute of Environmental Health Sciences found that regular users of permanent hair dye were 9% more likely to develop breast cancer compared with less frequent users. The increased probability reached 60% for African American women who dye their hair every five to eight weeks. Industry and NGO EWG respond.