Risk assessment of a mixture of pharmaceuticals and personal care products (PPCPs) in thermal waters of Kütahya, Türkiye

The increasing global consumption of pharmaceuticals and personal care products (PPCPs) and their persistence in the environment have raised concerns about their potential ecological and human health risks, especially in aquatic systems. Thermal waters, widely used for therapeutic and agricultural purposes, remain underexplored regarding PPCP contamination. This study presents a comprehensive environmental risk assessment (ERA) of 104 PPCPs in thermal waters from 22 sampling points across nine geothermal fields in Kütahya, Türkiye. A total of five PPCPs (caffeine, DEET, ephedrine, carbamazepine, and chlorphenamine) were quantified using a validated LC-MS/MS method. Caffeine exhibited the highest detection frequency (100%) and maximum concentration (43.191 ng L^-1), followed by DEET (90.9%) and ephedrine (77.2%). Risk quotients (RQs) were calculated based on predicted no-effect concentrations (PNECs) derived from ECOSAR v2.2, and the mixture risk quotient (MRQ) approach was applied to assess the cumulative ecological risks of PPCP mixtures. The results indicate that although most individual compounds pose low to medium ecological risk levels (RQ < 1), MRQ values exceeded concern thresholds (MRQ > 1) in several locations, suggesting potential chronic threats, especially to algae and invertebrates. No significant correlation emerged between PPCP levels and water parameters, indicating their persistence. Geological and hydrogeological factors, such as fault-controlled mixing between shallow and deep aquifers, were identified as pathways for contamination. These findings highlight the need for regulatory oversight of PPCPs in thermal waters and recommend safeguards, such as isolating well intakes from shallow aquifers, to reduce ecological and health risks.