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.