Nontarget Analysis of Drinking Water from Danish Waterworks: Profiling of Organic Micropollutants and Health Risk Screening

Quantitative nontarget analysis (qNTA) was used for a comprehensive screening of organic micropollutants (OMs) in groundwater-based drinking water, and their hazard and risk profiles were evaluated. Chemical structures were allocated for 278 features representing diverse chemical classes across the investigated 18 Danish waterworks, among which one is nonoperational. The micropollutant concentrations ranged from 0.03 to 1500 ng/L, with detection frequencies between 5 and 100%. In all of the waterworks in operation, the concentrations of pesticides and their metabolites were below 100 ng/L, the EU parametric value for drinking water. A quantitative risk screening of 87 OMs showed that they individually pose no immediate health risk for consumers, except some OMs whose risk screening was derived based on the threshold of toxicological concern. The remaining 191 micropollutants were qualitatively screened by the US-EPA’s Cheminformatics Hazard Module and revealed that 39 substances were categorized with “high” combined hazard score ratings. Additional work is needed to confirm compounds identified under probable structures (confidence levels of 2 and 3). The current study provided a snapshot of the prevalence of OMs in drinking water for human consumption, flagging those that can pose a potential hazard to humans and warrant follow-up investigations.