Kenichi KOSEKI

Evaluation of Drinking Water and Raw River Water by Ames Mutagenicity Assay in Shinano and Edo River System

Toshiya KOMATSU, Shuji HIMENO and Shoichi FUJITA

We measured the mutagen formation potential (MFP) of raw river water in three water purification plants in Shinano river system (Niigata Prefecture) and one plant in Edo river system (Tokyo Metropolitan Government), to investigate the level of mutagen precursor contained in drinking water source. This measurement was conducted by Ames mutagenicity assay using Salmonella typhimurium Strain TA100 without S9 mix and carried out monthly from March 2003 to February 2004. The means of MFP at Shinano river point ranged from 1340 to 1650 net rev./L, while the mean at Tokyo was 1780 net rev./L. We also measured the mutagenicity of drinking water in the same four plants to investigate the effect of water purification processes on the mutagenicity level. The means of mutagenicity at Shinano river point ranged from 970 to 1240 net rev./L, while the mean at Tokyo was 940 net rev./L. The mutagenicity level was lower in Tokyo, which was contrary to the MFP values. The fact was probably because advanced water treatment process composed of ozonation and activated carbon is introduced only in the plant in Tokyo. Results of this study suggest that the advanced process is effective for reducing mutagenicity level in drinking water.