Abstract
Recent toxicity information on dichloroacetic acid, one of drinking water disinfectant by-products was evaluated and the tolerable daily intake (TDI) via an oral administration was re-estimated. There are several new informations including metabolism, carcinogenicity and genotoxicity studies since the latest establishment of WHO drinking water quality guideline at 1992 was pronounced.
For general toxicity, TDI was calculated as 12.5 μg·kg-1·d-1 from LOAEL of 125 mg·kg-1·d-1, based on neurotoxicity in rats, divided by uncertainty factor of 10000. In addition to the evidence of carcinogenesis in the mouse liver, a recent chronic study demonstrated that dichloroacetic acid is also carcinogenic in the rat liver. Because there is no strong evidence for dichloroacetic acid-induced genotoxicity, TDI for carcinogenesis was considered as 3.6 μg·kg-1·d-1 from carcinogenic NOAEL of 3.6 mg·kg-1·d-1, divided by uncertainty factor of 1000. For reproductive/developmental toxicity, TDI was estimated as 104 μg·kg-1·d-1 from LOAEL of 31.25 mg·kg-1·d-1, based on testicular toxicity in rats, divided by uncertainty factor 300.
