[Study on the bladder calculi and bladder cancer induced by terephthalic acid in rats]

The carcinogenicity and calculogenesis of terephthalic acid on bladder was investigated. Terephthalic acid at doses of 5000, 500 and 50 mg/kg body weight/d were administrated to SD rats for 90 days consecutively. Control animals received normal feeds. Bladder calculi were induced in 5000 mg/kg (10/17) and 500 mg/kg (2/18) group. Calculi incidence of male rats was higher than that of female rats in 5000 mg/kg dose group. Bladder transitional cell cancer (4/17), atypical hyperplasia (5/17) and single hyperplasia (7/17) could be observed in 5000 mg/kg group. Atypical hyperplasia (10/18) and single hyperplasia (5/18) could be observed in 500 mg/kg group. Single hyperplasia (10/17) could be observed in 50 mg/kg group. The controls were normal except 1 case of single hyperplasia (1/18). There was a positive correlation between pathologic changes and dosage, but no significant correlation between pathologic changes and calculi incidence. Those rats without calculi produced some changes too, but no squamous metaplasia and carcinoma happened. The results suggested that under the study conditions, squamous cell carcinogenicity might be induced by terephthalic acid, and the calculi might not be the major factor inducing cancer.