Combination of effect-based monitoring and targeted screening of (drinking)water II: Effect directed analysis of compounds responsible for bioassay activity

Bioassays are increasingly applied in the monitoring of chemical water quality. To determine whether elevated bioassay activities indicate a risk, identification of the active substances is needed. This study investigated the presence and fate of 10 biological activities detected by CALUX bioassays and chemical contaminants detected by targeted screening in sources and treatments of drinking water companies in the Dutch parts of the Rhine and Meuse catchments. This was reported in the accompanying article. As the correlations elucidated by the hierarchical cluster analysis approach did not in all cases reveal the causative compounds, effect directed analysis (EDA) was performed and reported in this article. By embedding the p53 and the Nrf2 CALUX bioassays (for genotoxicity and oxidative stress, respectively) in an earlier developed high throughput EDA platform, the identification of contributors to multiple different endpoints was achieved. The platform combined microfractionation, miniaturised bioassays and targeted screening using high resolution mass spectrometry, and was applied to eight samples. Natural and synthetic steroid hormones and their metabolites were identified as contributors to androgenic, estrogenic, glucocorticoid and progestogenic activities. Fourteen pesticides were found to contribute to anti-androgenic, anti-progestogenic and/or cytotoxic activities, underlining the increasing public concern of pesticide use. Two pharmaceuticals contributed to oxidative stress in the WWTP effluent sample. Although the p53 CALUX assay was successfully integrated in the EDA platform, is was not applied to water samples due to lack of detectable activity. The applied EDA platform proved to be powerful to identify bioactive compounds in water with a high endpoint coverage in a high throughput format. EDA creates an integrated and risk-based view on those contaminants that deteriorate chemical water quality.