Do hair dyes cause cancer?
Permanent hair dyes produced before 1980 contained ingredients that are now known to cause cancer. These were eliminated from dyes produced in the United States in 1979, when industry-wide changes in the formulation of hair dyes were instituted. It has generally been assumed that personal use of today’s hair dyes is safe, even though there is some evidence that at least one cancer causing agent–known as 4-ABP–can be present in some dyes or dye-lots. It is not a deliberate ingredient, but an unintentional by-product of the manufacturing process. Another problematic chemical–known as 2,3-Naphthalenediol–was banned from hair dyes in Europe in 2006, but may be present in some US hair products. Because of continued concerns about the potential risks of such chemicals, along with the observation that the incidence of a type of cancer known as lymphoma has doubled in the last 20 years–while the popularity of permanent hair dyes has also increased–scientists have investigated whether hair dye
