Intra-uterine exposure to saccharin and risk of bladder cancer in man.

Animal experiments show that rats fed saccharin are more likely to develop bladder tumours if they have been exposed to saccharin in utero through their mothers' food. The risk of bladder tumours in humans following in utero exposure to saccharin has not been evaluated previously. In Denmark the use of saccharin increased sharply during the second World War as a result of scarcity of sugar, and import and export figures indicate that saccharin consumption was on average 4-5 times higher during the war-time period than in the pre-war decade. The risk of bladder tumours at ages 20-34 was 1.0 (95% confidence interval 0.7-1.6) among men born in 1941-1945 compared with men born 1931-1940. Among women the risk was 0.3 (0.1-1.0). This study provides no evidence of an increased risk of human bladder cancer during the first 30-35 years of life associated with in utero saccharine exposure.