Predicting pharmaceutical concentrations and assessing risks in the aquatic environment using PERK: A case study of a catchment area in South-West England.

The aim of this study was to introduce a model to predict pharmaceuticals concentrations in the aquatic environment and their environmental impacts using the Risk Quotient (RQ) approach. The model was trained using: (i) high resolution dataset on pharmaceuticals' concentration in wastewater and receiving environment in a river catchment, (ii) understanding of pharmaceuticals' discharge points in the catchment, (iii) fate of pharmaceuticals during wastewater treatment and in the receiving environment, (iv) high resolution per-postcode pharmaceutical prescription data. A total of 41 pharmaceuticals were evaluated, with successful predictions achieved for concentrations falling within the range of 0.7 (influent: 37 %, effluent: 39 %, river: 29 %) to 1 % (influent: 56 %, effluent: 58 %, river: 48 %) of the measured values. Importantly, our risk assessment demonstrates significant environmental risks associated with specific pharmaceuticals, with strong alignment (86 %) between assessments based on predicted and measured data, underscoring the reliability of our model in assessing environmental risks. The observed variability in predicted and measured concentrations underscores the necessity for ongoing model refinement, particularly in regions with notable discrepancies such as wastewater treatment plant (WWTP) C. Overall, our study illustrates the intricate dynamics of pharmaceutical contamination in aquatic ecosystems, emphasizing the crucial need for continued research in this field.