If you use permanent hair dyes at least once a month you should
know about a 2001 study from researchers at the University of
Southern California that analyzed the association between hair
dying activity and bladder cancer.
There was no association between semi-permanent or temporary
hair dyes and bladder cancer. (See Safer Ways to Color Your
While the study was not a clinical cancer trial, it did make a
determination of those who are at highest risk from use of
* Women who use permanent, hair dyes once a month for 1 year or longer have twice the risk of bladder cancer.
* Women who use permanent hair dyes for 15 or more years at least monthly have three times the risk of bladder cancer using permanent dyes for 15 or more years when the dyes are used monthly or more frequently.
* Those who have worked as hair dressers or barbers for 10 years or more have five times the risk of bladder cancer.
The researchers note that the exposure of concern is to a family of chemicals called Arylamines, an ingredient in many oxidative hair dyes, which is a known risk factor for bladder cancer and found to cause cancer in experimental animals.
The study was considered of enough concern in Europe that the European Commission, a body that drafts legislation for the European Union, has changed their policy to demand information from manufacturers about ingredients contained in hair dyes. The United States does not required manufacturers to file data on ingredients or report cosmetic-related injuries.
Darker hair dyes cause higher risk because of the increased number of chemicals.