The International Journal of Cancer 2003 (105) reports that male hairdressers were shown to have an increased risk of bladder cancer in the 60’s are now at normal levels. (The report didn’t say whether the rest of us had merely caught up although there was some suggestion that brilliantine was carcinogenic).
However, scalp and neck cancers were shown in Swedish data to be more prevalent amongst male hairdressers probably because they had a higher incidence of usage themselves.