“…As for the genotoxicity of tap water, Urano et al (1995) performed the Ames mutagenicity test, which is one of the typical genotoxicity tests along with the umu test, for Japanese tap water samples concentrated using a solid-phase extraction method, and they reported results ranging from less than 470 to 9,200 net rev./L. Since then, however, there have been few reports on how the genotoxicity of tap water has changed, and no investigations have reported the occurrence of genotoxicity nationwide using the standardized umu test.…”