Abstract: Purpose : To explore the mutagenicity of organic ext ract s of tap water in a certain city in mice. Methods : Each 200 L of water was collected separately from Huai river source water , water of clarifying filt ration , chlorinated tap water and reservoir’s water. After being adsorbed and concent rated , water samples were poured into mouse stomaches. Micronucleus frequency in mouse thoracic bone-marrow polychromatic erythrocyte ( PCE) and sperm deformity rate were determined. Results : Mutagenicity of some degree were determined from Huai river source water and chlorinated tap water. The order of mutagenic intensity was as follows ; chlorinated tap water > reservoir’s water > source water > water of clarifying filteration. Conclusions : The source water was contaminated by organic mutagens. After coagulation and precipitation , mutagenicity of source water decreased because some mutagenic organic chemicals could be removed. While chlorination increased mutagenicity of tap water.

Key words: water pollution, organic extract, mutagenicity, mouse