Genotoxicity Evaluation of Irrigative Wastewater from Shijiazhuang City in China

In the present study, the wastewater sample collected from the Dongming discharging river in Shijiazhuang city was analysed using both chemical analysis and biological assays including the Salmonella mutagenicity test, micronucleus test and single-cell gel electrophoresis. Chemical analysis of the sample was performed using gas chromatography mass spectrometry and inductively coupled plasma mass spectrometry. The Salmonella mutagenicity test was performed on Salmonella typhimurium TA97, TA98, TA100 and TA102 strains with and without S9 mixture. The mice received the wastewater in natura through drinking water at concentrations of 25%, 50%, and 100%. One group of mice was exposed for 2 consecutive days, and the other group of mice was exposed for 15 consecutive days. To establish the levels of primary DNA damage, single-cell gel electrophoresis was performed on treated mouse liver cell. The concentrations of chromium and lead in the sample exceeded the national standard (GB20922-2007) by 0.78 and 0.43-fold, respectively. More than 30 organic compounds were detected, and some of the detected compounds were mutagens, carcinogens and environmental endocrine disrupters. A positive response for Salmonella typhimurium TA98 strain was observed. Mouse exposure via drinking water containing 50% and 100% of wastewater for 15 consecutive days caused a significant increase of MN frequencies in a dose-response manner. Mouse exposure via drinking water containing 50% and 100% of wastewater for 15 consecutive days caused a significant increase of the Olive tail moments in a dose-response manner. All the results indicated that the sample from the Dongming discharging river in Shijiazhuang city exhibited genotoxicity and might pose harmful effects on the local residents.