Abstract: BACKGROUND AND AIM: To explore the mutagenic effects of reclaimed water in Tianjin. MATERIALS AND METHODS:Reclaimed water in dry and rainy periods were collected. Reverse phase C-18 solid-phase extraction (RP-C18SPE) was used for the extraction of organic compounds from water samples. Ames test, cytokinesis-block micronucleus test and plasmid DNA breakage test was used to assess the damage of water samples on genetic materials. Moreover, PCR-DNA gene sequencing method was used to examine the mutatgenic effects of water samples on some exons of p53 gene. RESULTS: Ames test showed that after metabolism by S9 ,both untreated reclaimed water and treated reclaimed water, except untreated reclaimed water of rainy period, could induce mutation of TA98 and TA100 strains with dose-response relationship(P<0.05). Frameshift and base replacement mutation effects of urban reclaimed water were also found. There were three doses: 16.7,33.3 and 66.7 ml/ml(the denominator was original water) in micronucleus test, and the micronucleus number was only slightly increased at 66.7 ml/ml, but there was no significant difference compared with control group. DNA breakage test demonstrated that with increasing doses of urban reclaimed water, plasmid damage was also significantly enhanced(P<0.05). In addition , linear DNA appeared when plasmid was treated by dry period samples, and this phenomenon might be due to the different compounds of water sample extraction. Gene sequencing method testified that organic extraction of urban reclaimed water could induce mutation of p53 gene in human embryo liver cell(L-02 cell). CONCLUSION: Urban reclaimed water, which showed mutagenic effects in some extent, might pose potential hazards to environment and health.

Key words: reclaimed water, solid-phase extraction, mutation, p53 gene