Time- and dose-dependent development of potassium bromate-induced tumors in male Fischer 344 rats

Potassium bromate (KBrO3) is a rodent carcinogen and a nephro- and neurotox icant in humans. KBrO3 is used in cosmetics and food products and is a by-p roduct of water disinfection by ozonization. KBrO3 is carcinogenic in the r at kidney, thyroid, and mesothelium and is a renal carcinogen in the male m ouse. The present study was designed to investigate the relationship of tim e and dose to bromate-induced tumors in male Fischer 344 (F344) rats and to provide some insight into the development of these tumors. KBrO3 was disso lved in drinking water at nominal concentrations of 0, 0.02, 0.1, 0.2, and 0.4 gn and administered to male F344 rats as the sole water source for 12, 26, 52, 78, or 100 wk. Renal cell tumors were present after 52 wk of treatm ent only in the high-dose group. Mesotheliomas developed after 52 wk of tre atment on the tunica vaginalis. Mesotheliomas were present at sites other t han the testicle after 78 wk of treatment, indicating that their origin was the testicular tunic. Thyroid follicular tumors were present as early as 2 6 wk in 1 rat each from the 0.1- and 0.2-g/L groups. The present study can be used as a basis for the determination of dose-time relationships of tumo r development for a better understanding of KBrO3-induced cancer.