Subchronic toxicity evaluation of potassium bromate in Fischer 344 rats

• Male F344 rats exposed to 400 mg/L potassium bromate in drinking water had increased kidney weights.
• Hyaline droplets were observed in renal tubules of F344 rats exposed to 200–400 mg/L potassium bromate in drinking water.
• There were no KBrO3-related microscopic findings in the lung, liver, thyroid, and tunica vaginalis.
• A NOEL of 100 mg/L KBrO3 (8.1 mg/kg/day) was selected based on the absence of microscopic alterations in the kidney.

Male F344 rats were exposed to potassium bromate (KBrO3) in drinking water at concentrations of 0, 5, 20, 100, 200, or 400 mg/L for 2 or 13 weeks. Endpoints evaluated included clinical observations, body weights, serum chemistry, gross pathology, organ weights, and select tissue histopathology (kidney, lung, liver, thyroid, and tunica vaginalis). Weekly body weight and water consumption means were similar between KBrO3 and control groups throughout the study. Increases in kidney weights were observed in rats of the 400 mg/L group following 2- or 13-weeks exposure. Hyaline droplets were observed in renal tubules of rats of the 200 and 400 mg/L groups following 2 weeks exposure and in rats of the 400 mg/L group at 13 weeks. There were no KBrO3-related microscopic findings in the lung, liver, thyroid, and tunica vaginalis at the 2- and 13-week time points. A no observed effect level of 100 mg/L KBrO3 (8.1 mg/kg/day) was selected based on the absence of microscopic alterations in the kidney.