Effects of subchronic exposure of rats to dichloramine and trichloramine in drinking water

The subchronic toxicity of 0.2-200 ppm dichloramine and 0.2-90 ppm trichlor amine in the drinking water of rats was investigated using biochemical, hem atological, and histopathological parameters. Animals in the highest dose g roups consumed 5-15% less fluid than controls with no significant decrease in body weight gain. No clinical signs of toxicity were observed in either case. Both males and females dosed with 90 ppm trichloramine had significan tly increased relative kidney/body weights and the females had increased he patic glutathione S-transferase and UPD-glucuronosyltransferase activities. No significant changes were detected in other xenobiotic metabolizing enzy mes or in serum biochemistry, urine biochemistry, or hematology. Both dichl oramine and trichloramine induced minimal to mild adaptive histopathologica l changes in thyroids and kidneys of animals of both sexes. Dichloramine, b ut not trichloramine, was associated with histological changes in the gastr ic cardia characterized by epithelial hyperplasia at concentrations of 2 pa m and above in the males and 200 ppm in the females. This study indicates t hat dichloramine produced mild histological effects at drinking water conce ntrations of >0.2 ppm in males (0.019 mg/kg/day) and >2 ppm in females (0.2 6 mg/kg/day) while trichloramine produced biochemical and mild histological effects at levels of >2 ppm both in males (0.23 mg/kg/day) and in females (0.29 mg/kg/day). (C) 2000 Academic Press.