Saccharin was reported to cause urinary bladder cancer in male rats when fed at high doses in a two-generation study, which led to a ban on the use of saccharin in Canada. However, no carcinogenic effect has been observed in other animal experiments conducted with mice, hamsters, or monkeys. Furthermore, numerous epidemiological studies have indicated that there was no relationship between saccharin consumption and the risk of bladder cancer in the human population. Sodium saccharin produces urothelial bladder tumors in rats by the formation of a urinary calcium phosphatecontaining precipitate, which is not relevant to humans because of critical interspecies difference in urine composition. Consequently, in 1999 IARC (International Agency for Research on Cancer) concluded that saccharin and its salts cannot be classified as to their carcinogenicity in humans. In 2010, the EPA (Environmental Protection Agency) of the United States removed saccharin from its list of hazardous substances. It is expected that the use of saccharin in foods might be expanded because saccharin is currently considered safe.