Behavior
Behavior
Behavior
Scientific insight and expert advice on behavior, personality traits and why we act how we do.
Link between hair dye and breast cancer is possible, says new report
A new report is raising concerns about permanent hair dyes and chemical straighteners used by millions of women. It found a possible link between those products and an increased risk of breast cancer. NBC News medical contributor Dr. Natalie Azar joins TODAY to tell you what you need to know.