Comprehensive Toxicity Evaluation of Environmental Water Using Various Bioassay Techniques

The present study was carried out to evaluate comprehensively the estrogenicity, immunotoxicity and mutagenicity of environmental water concentrates prepared by the XAD-2 resin column concentration method. This investigation focused on water from the river basin of Lake Biwa-Yodo River. Estrogenicity was detected by the yeast two-hybrid system and the measurement of alkaline phosphatase activity in human endometrial adenocarcinoma cell line (Ishikawa cells). Although the two methods differed in sensitivity and magnitude of estrogenic activity for lake water and river water containing endocrine-disrupting chemicals (EDCs), estrogenicity was detected in all sampling points except the Katsura River (Miyamae bridge). These results suggested the co-existence of materials with EDCs in environmental water, which inhibited the detection of estrogenic activity. Immunotoxicity was evaluated by the mouse splenic lymphocyte mitogenesis test using lipopolysaccharide and concanavalin A as specific mitogens for B cells and T cells, respectively. Some of the water samples showed specific depression effect on B cell and T cell mitogenesis. Furthermore, the Salmonella/microsome assay (Ames test) with TA98 and TA100 strain series was used to determine the mutagenicity. In all the sampling points, the direct/indirect-frameshift mutagenicity was detected. These results indicated that the yeast two-hybrid system and the measurement of alkaline phosphatase activity in Ishikawa cells, the lymphocyte mitogenesis test and the Ames test are important for evaluating comprehensively each endpoint because there is no relevance among these different toxicities.