Exposure to hair dyes, especially dark ones, raises the risk of certain types of the disease, notably bladder cancer, they said. The latest working group report of the International Agency for Research on Cancer said positive cancer tests in rats led to the withdrawal of some of the dyes earlier. The group also looked at the personal use of hair dyes but decided there was ''inadequate'' evidence to come to a judgment as to whether or not it would lead to an increased cancer risk.
Dr Robert Baan and colleagues from the France-based agency said many studies were carried out on cancer in hairdressers, beauticians and barbers.
''A small, but consistent, risk of bladder cancer was reported in male hairdressers and barbers,'' their report said.