Drinking Water Quality Assessment by Nontargeted Analysis and Human Cytochrome P450 3A Enzyme Activity

Drinking water treatment plants (DWTPs) are primarily not designed to eliminate emerging organic contaminants, hence plenty of compounds are frequently determined in drinking waters, leading to unknown risks for human health. Nontarget analysis (NTA) combined with bioassays can provide a detailed assessment of water quality and treatment performance. In this study, an NTA and human cytochrome P450 3A (CYP3A) enzyme activity assay was conducted for raw and treated water samples from three DWTPs located within the Czech Republic. The results revealed significant mutual differences in the quality of raw and treated waters between the DWTPs. Although many compounds were apparently removed, additional features (51–72) were detected in treated water, indicating that transformation products might have been formed. Additionally, two potential disinfection byproducts were determined. Furthermore, dozens of chemicals were tentatively identified in raw and treated waters with high confidence at level 2, mostly pharmaceuticals, pesticides, and their respective metabolites. The enzyme activity of CYP3A was significantly inhibited in raw water samples from all DWTPs and in one treated water sample. These findings were in line with the results obtained from nontargeted analysis. The present findings demonstrate the usefulness of the CYP3A enzyme activity in revealing the possible impact on xenobiotic metabolism in DWTPs.