CARCINOGENICITY OF POTASSIUM BROMATE ADMINISTERED IN THE DRINKING-WATER TO MALE B6C3F(1) MICE AND F344 N RATS/

Ozone has been proposed for water disinfection because it is more effi cient than chlorine for killing microbes and results in much lower lev els of carcinogenic trihalomethanes than does chlorination. Ozone lead s to formation of hypobromous acid in surface waters with high bromine content and forms brominated organic by-products and bromate. The car cinogenicity and chronic toxicity of potassium bromate (KBrO3) was stu died in male B6C3F(1) mice and F344/N rats to confirm and extend the r esults of previous work. Mice were treated with 0, 0.08, 0.4, or 0.8 g /L KBrO3 in the drinking water for up to 100 wk, and rats were provide d with 0, 0.02, 0.1, 0.2, or 0.4 g/L KBrO3. Animals were euthanatized, necropsied, and subjected to a complete macroscopic examination. Sele cted tissues and gross lesions were processed by routine methods for l ight microscopic examination. The present study showed that KBrO3 is c arcinogenic in the rat kidney, thyroid, and mesothelium and is a renal carcinogen in the male mouse. KBrO3 was carcinogenic in rodents at wa ter concentrations as low as 0.02 g/L (20 ppm; 1.5 mg/kg/day). These d ata can be used to estimate the human health risk that would be associ ated with changing from chlorination to ozonation for disinfection of drinking water.