Risk for cancer of the urinary bladder among hairdressers in the Nordic countries.

Several studies have indicated an increased risk for cancer of the urinary bladder among hairdressers. In a Danish linkage between census data and cancer register data both male and female hairdressers have an elevated risk for bladder cancer. The risk for lung cancer is close to unity, indicating that occupational factors rather than smoking, may be responsible for the increased risk for bladder cancer among hairdressers. To evaluate this hypothesis we conducted a collaborative analysis of data from similar linkages in Finland, Norway, and Sweden. The combination of high risk for bladder cancer and low or no risk for lung cancer was not found in the other Nordic countries; however, statistically significant increased risks for both bladder and lung cancer were found among male hairdressers in both Norway and Sweden. The relative risks for bladder cancer were of the same magnitude as the relative risks for lung cancer.