Personal use of hair dyes is very common, with estimates that 50% or more of women and 10% of men over age 40 color their hair. However, with social distancing guidelines in place amidst the ongoing pandemic, many people have foregone their regular hair salon appointments. As natural hair colors get rooted out, let’s cut to a layered question: do permanent hair dyes increase cancer risk?
Decades of research, conflicting results
Hair dyes come in three major varieties: oxidative (permanent), direct (semi-permanent or temporary), and natural dyes. Most hair dyes used in the US and Europe — both do-it-yourself dyes and those used in salons — are permanent dyes. They undergo chemical reactions to create pigment that deposits on hair shafts and may pose the greatest cancer risk.
People are exposed to chemicals in hair dyes through direct skin contact or by inhaling fumes during the coloring process. Occupational exposure to hair dye, as experienced by hairstylists, has been classified as probably cancer-causing. However, it remains unclear whether personal use of permanent hair dyes increases risk for cancer or cancer-related death.
Many studies have explored the relationship between personal hair dye use and risk of cancer or cancer-related death. Conflicting findings have resulted from imperfect studies due to small study populations, short follow-up times, inadequate classification of exposures (personal or occupational) or hair dye type (permanent versus non-permanent), and incomplete accounting of cancer-specific risk factors beyond permanent hair dye use.
Permanent hair dye does not appear to increase overall cancer risk, says recent study
In a recent study in The BMJ, researchers at Harvard Medical School evaluated personal hair dye use and risk of cancer and cancer-related death. The study authors analyzed survey data from 117,200 women enrolled in the Nurses’ Health Study, collected over 36 years beginning