Toxicology and carcinogenesis studies of bromochloroacetic acid (CAS No. 5589-96-8) in F344/N rats and B6C3F1 mice (drinking water studies).

BACKGROUND: Bromochloroacetic acid occurs as a by-product of water disinfection. We studied the effects of bromochloroacetic acid in drinking water on male and female rats and mice to identify potential toxic or cancer-related hazards.

METHODS: We gave drinking water containing 250, 500, or 1,000 mg of bromochloroacetic acid per liter of water to groups of 50 male and female rats and mice for 2 years. Control animals received the same tap water with no chemical added. At the end of the study tissues from more than 40 sites were examined for every animal.

RESULTS: Survival was similar for rats and female mice receiving bromochloroacetic acid and the controls; survival of 1,000 mg/L male mice was less. Male rats receiving bromochloroacetic acid had increased rates of malignant mesotheliomas. Adenomas of the large intestine were seen in both male and female rats receiving the highest concentration of bromochloroacetic acid. Exposed female rats also had increased incidences of multiple fibroadenomas of the mammary gland. Slightly increased incidences of liver hepatocellular adenomas in male and female rats and pancreatic islet adenomas in male rats were also observed in exposed animals. Male and female mice exposed to bromochloroacetic acid had increased rates of a variety of liver cancers.

CONCLUSIONS: We conclude that bromochloroacetic acid in the drinking water caused mesothelioma in male rats, multiple fibroadenomas of the mammary gland in female rats, and adenomas of the large intestine in both male and female rats. Adenomas of the liver in male and female rats and of the pancreatic islets in male rats may also have been related to bromochloroacetic acid exposure. We conclude that bromochloroacetic acid caused liver cancer in male and female mice.