Health risk identification of typical groundwater using bioassays and chemical methods

The toxicity and associated health risks of typical contaminated groundwater were evaluated using bioassays, the SOS/umu test and the micronucleus assay, with a comparison of identified risks based on bioassay and chemical methods. An analysis of 15 water extracts showed that a lifetime cancer risk (LCR) value of 10(-6) was recorded for 47% of water extracts. These results indicated that some water extracts did not exhibit toxicity when analysed using one type of bioassay, yet they indicated high toxicity when analysed using another method. Our results also demonstrated that the LCR values from bioassays were generally greater (2.4-fold(max)) than those derived from chemical analysis, a finding indicating that risks can be underestimated or false-negative results can be obtained when only chemical-based methods or even just one bioassay is used. This study suggests that the use of multiple bioassays should be considered to be an efficient method and a comprehensive method should be established for risk assessment. Our findings also suggest that groundwater and freshwater in the studied area might pose significant health risks and exhibit toxicity.