Re-examination of the genotoxic activity of water taken from the Songhua River in P. R. China.

The Songhua River, in northeast China, has heavy organic contamination due to domestic sewage and industrial wastewater. Thus, it is important to further determine its genotoxic activity, which is a potential hazard for human health. Short-term genotoxic bioassays using Salmonella, the cytokinesis-block micronucleus cytome assay, and mouse liver cell comet assay were employed to further examine the genotoxic activity of diethyl ether extracts of water samples taken from the Songhua River. Ames test results showed that there were still frame-shift mutagens, both direct and indirect, in water samples at doses of 5.0 or 7.0 L water equivalent/plate. The mutagenicity seems to be less when compared with the results from 2002 to 2003. A dose-response relationship was also obtained between DNA damage in mouse liver cells by comet assay and micronuclei formation by CBMN assay. These results indicate that the water samples showed genotoxic activity with a mutagenic potency. 88 and 104 compounds, respectively, were identified in summer and winter water sample extracts by gas chromatography-mass spectrometry analysis. Four priority pollutants listed by the United States Environmental Protection Agency and six priority pollutants listed by the Chinese Environment Protection Agency were found in summer or winter water samples, respectively. The results indicate that the diethyl ether extracts of surface water samples taken from the Songhua River still show genotoxic activity (≥3.0 L water). The risks of potential carcinogenicity for human health in the Songhua River should be studied further.

Reproductive toxicity of perchlorate in rats.

Perchlorate, as an oxidizer, has many applications such as explosives and pyrotechnics, especially in rocket propellants and missile motors. Because it was found in water including wells and drinking water in the US, its effect on human health was being noted. However, the reproductive toxic effect on perchlorate is still unclear. In present study, the effects of repeated exposure to perchlorate on reproductive toxicity were evaluated in Wistar rats. The rats were treated orally with perchlorate at doses of 0.05, 1.00 or 10.00 mg/kg body weight (b.w.) daily for 8 weeks. The levels of T3 and T4 hormones in the rat serum were detected by radioimmunoassay kit. The indexes of reproduction, percentage of organ in body weight (%) and frequency of abnormal sperm cells were also analyzed in this study. DNA damage in testicular cells was evaluated by Comet assay. The levels of MDA, GSH and SOD were examined in testicle tissues of rats by ELISA. The expression of c-fos and fas protein was examined in testicle tissues by immunohistochemistry. The results showed that perchlorate did not affect the body weight of rats. Perchlorate also significantly decreased indexes of live birth and weaning in the groups of 1.00 and 10.00 mg/kg, and viability index only in the 10.00 mg/kg group (P < 0.05). Perchlorate also significantly decreased the serum level of T3 in male rats of 1.00 and 10.00 mg/kg groups, increased the rate of sperm abnormality (10.00 mg/kg), potentially caused DNA damage in testicular cells and altered the status of oxidative stress in male rats. In addition, because of the increase in the expression of fas and c-fos protein in testicle tissues, perchlorate could induce apoptosis in spermatogenesis. Thus, these findings indicate that perchlorate could cause DNA damage in testicular tissues and reduce testicular spermatogenic ability, resulting in reproductive toxicity.