Predicted environmental concentrations to prioritize and determine geographical and temporal variation of 810 pharmaceuticals in wastewaters and rivers

Pharmaceuticals are considered emerging contaminants (ECs) due to their increasing presence in surface waters, largely caused by discharges from industries, domestic consumption and hospitals, and uncomplete elimination in wastewater treatment plants (WWTPs). Their persistence poses environmental risks making it crucial, yet challenging, to prioritize compounds for monitoring. Predicted Environmental Concentrations (PECs) offer a valuable tool for estimating pharmaceutical levels in WWTP effluents and river waters, based on consumption data, excretion rates, removal efficiencies, and hydrological factors. This study calculates the PEC for all prescribed pharmaceuticals (810 substances) from 2014 to 2021 in Catalonia (Spain) and determines the concentrations in WWTP effluents and surface waters. In 2021, out of 810 pharmaceuticals, 261 compounds had concentrations higher than the 10 ng L⁻¹ threshold posed by European medicines agency (EMA) as concentrations of risk and increased in PEC concentrations caused by increased consumption and water scarcity. The results show the usefulness of PECs for prioritizing pharmaceuticals in environmental monitoring programs and highlight the importance of region-specific data to determine time trends and geographical distributions. This approach supports the implementation of effective strategies for managing pharmaceutical contamination.