Beyond the Drinking Water Directive: The use of reporter gene assays as an added tool for effect-based monitoring of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in drinking water sources.

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are legacy organic micropollutants (OMPs) that are sporadically detected in drinking water (DW) sources. The European Drinking Water Directive requires EU member states to monitor 5 PAHs in DW and its sources. The Dutch national regulations require 6 additional PAHs to be monitored and 7 polychlorinated biphenyls (PCBs). These indicator compounds act as representatives for large compound classes. PCBs alone comprise 209 congeners, it is evident that conventional chemical target analysis (GC-tQ-MS) alone is not sufficient to monitor these entire compound classes. This study investigated the application of reporter gene assays as effect-based methods (EBMs) to monitor PAHs and PCBs in DW sources. Herein, it was assessed what added value the bioassays can bring compared to the current approach of chemical target analysis for PCBs and PAHs. Regulated and non-regulated PAHs and PCBs were tested in four bioassays to determine the relative potency factors (RPFs) for these compounds. Non-regulated congeners were found to be active in the PAH-CALUX and anti-AR CALUX. An assessment of surface water (SW) spiked with standard mixtures containing PAHs and PCBs confirmed the predictable behavior of the PAH-CALUX. Moreover, the bioassay was able to detect AhR-mediated activity caused by non-regulated PAHs and PCBs, whereas this would have been missed by conventional chemical target analysis. Last, a field study was conducted in Dutch DW sources at six sampling moments. The PAH-CALUX detected AhR-mediated activity at all sampling moments and an ecological effect-based trigger (EBT) value was exceeded on multiple accounts. Combined application of GC-tQ-MS and the PAH-CALUX ensures compliancy with monitoring legislation and provides additional insights into potential hazards to humans and the environment.