Biomonitoring - relevance of bioassays in water treatment

Human-impacted surface, ground and drinking water can contain a complex mixture of micropollutants, such as pharmaceuticals, pesticides and industrial compounds. These potentially harmful chemicals are often found at low concentrations, and targeted chemical analysis cannot detect all the hazards present in a sample. Suspect screening and non-target analysis can identify a larger number of compounds but cannot provide information about the potential toxic effects of the micropollutant mixture. To detect these potentially toxic mixtures, effect-based monitoring using bioanalytical tools (i.e., in vitro bioassays and well plate-based in vivo assays) can be applied in parallel to chemical analysis.

Bioassays can account for mixture effects that targeted chemical analysis can miss and are risk-scaled as more potent chemicals have a greater effect in the assay. Consequently, effect-based methods have been recommended to complement chemical analysis in water quality monitoring. Bioassays based on different stages of cellular toxicity pathways including induction of xenobiotic metabolism, receptor-mediated effects, adaptive stress responses and apical effects have been widely applied to evaluate the effect of different water extracts. This raises questions about which bioassays to use and how many should be applied for water quality assessment.

The aim of this presentation is to identify bioassays commonly applied to water extracts and provide guidance on assay selection and subsequent interpretation. Examples will be given for how cell-based assays have been utilized to analyze important chemicals of concern, as well as complex mixtures. Data analysis including bioanalytical equivalent concentrations (BEQ), limit of detection (LOD) and effect concentration (EC) will be described.