Abstract
The Ames mutagenicity levels of tap water at 23 cities in Japan were investigated during a year for indicating the need of evaluation and control of gene toxicity of tap water. The mutagenicity values were ranged from under the detection limit to 9,200 net rev.·l-1, and their difference was about 30 times. The mutagenicity values higher than 3,000 net rev.·l-1 were about one fourth of them. There was no significant relation between the mutagenicitv of tap water and the kinds of the water treatment process or the water source except ground water. The mutagenicity values tended to be higher in winter and spring, and their annual means at each city were ranged from 290 net rev.·l-1 to 4,400 net rev.·l-1. It means that there is 15 times difference of the gene injury risk in these areas. Furthermore, the relations between the mutagenicity values and the conventional water qualities were not clear. Consequently, it was indicated that the Ames mutagenicity was available for evaluation and control of water safety in addition to the conventional water qualities. Especially, the mutagenicity of tap water should be evaluated and controlled in the area where the mutagenicity was clearly higher (above 3,000 net rev.·l-1) than the other areas.
