Identification of trihalomethanes in drinking water and assessment of their toxicity, mutagenicity and carcinogenicity

Dichlorobromomethane (DCMB) and dibromochloromethane (DBCM) isolated from chlorinated drinking water were tested for toxicity, mutagenicity and carcinogenicity. Both agents proved mutagenic in a "dessicator" modification of the Ames test using Salmonella typhimurium TA98 and TA100 in the presence of exogenous metabolic activation. In aquarium Danio rerio fish tests, LD50/30 was 250 mg/l for both compounds. Both agents induced hepatocellular carcinoma in fish: DCMB--in 11 out of 29 animals (at 16.5 weeks) and DBCM--in 3 out of 16 (at 26.5 weeks). These data merit further investigation of the agents' carcinogenicity in chronic experiments in rodents.