Occurrence, bioaccumulation, and ecological risks of pharmaceutical active compounds in an urbanized estuary on the São Paulo Coast, Brazil

This study aimed to evaluate the occurrence, bioaccumulation, and ecological risks of ten pharmaceutically active compounds (PhACs) in an urbanized estuarine system on the São Paulo coast, Brazil. Water samples were collected from two tributaries of the Itanhaém River (Guaú and Campininha Rivers), and liver and muscle tissues of Genidens genidens were analyzed to assess trophic transfer. Samples were processed by solid-phase extraction and analyzed using liquid chromatography–tandem mass spectrometry (LC–MS/MS). All ten target PhACs were detected in water from the Campininha River, with concentrations ranging from <MLOQ to 653.15 ng/L, while only five compounds were detected in the less urbanized Guaú River, with concentrations up to 7.69 ng/L. Benzoylecgonine, a cocaine metabolite, was the only compound detected in fish tissues, with concentrations reaching 1.49 ng/g in liver and 1.78 ng/g in muscle, indicating bioaccumulation and trophic transfer. Ecological risk assessment based on risk quotient (RQ) analysis revealed that losartan posed a high acute risk to crustaceans (RQ = 2.03), acetaminophen presented a high chronic risk to fish (RQ = 1.53), and caffeine and benzoylecgonine exhibited moderate risks to sensitive aquatic taxa. These findings demonstrate that PhACs occur ubiquitously in urban estuaries and may pose ecological risks even at nanogram-per-liter levels. The results highlight the need for improved wastewater management and reinforce the importance of incorporating pharmaceutical contaminants into coastal monitoring and regulatory frameworks. • First assessment of ten pharmaceuticals in an urban estuary on São Paulo coast • Caffeine, acetaminophen, losartan, and benzoylecgonine showed highest levels • Benzoylecgonine bioaccumulated in liver and muscle of Genidens genidens • Losartan posed high acute risk to crustaceans; acetaminophen high chronic risk to fish • Findings highlight need for improved wastewater management in coastal regions