Occupational bladder cancer and cigarette smoking in West Yorkshire.

This paper reports the preliminary findings of a case-controlled study of bladder cancer in parts of West Yorkshire. The first 991 cases have been analysed and the results of the occupational exposure for 5 occupations are reported. There is an increased risk of bladder cancer associated with smoking cigarettes in both males and females. These results take both the age and the year of diagnosis into account and are statistically significant. Chemical industry workers and printers have been shown statistically to have a high risk ratio, whereas leather workers, hairdressers and dye-users have a statistically insignificant risk ratio. For process workers in the dye manufacturing industry the length of service is significantly correlated with the risk of bladder cancer and so is the age at which a man first becomes a process worker.