Patterns of pharmaceutical contamination in streams of European cities across urbanisation gradients: Potential impacts on One Health

Pharmaceuticals are Contaminants of Emerging Concern, with known effects on aquatic organisms such as increased mortality and reproduction inhibition. This study aimed to provide a comprehensive overview on occurrence of pharmaceuticals in European urban streams, and to assess the patterns and factors influencing their qualitypresence in the water. Sixteen pharmaceuticals from 6 therapeutic groups were detected in 102 sites sampled in 2022–2023 within 5 European cities (Coimbra-Portugal, Toulouse-France, Benevento-Italy, Ghent-Belgium, and Oslo-Norway). Pharmaceuticals and their mixtures were observed in 91 % and 79 % of the sites, respectively. Irbesartan, bisoprolol and carbamazepine were found in more than 50 % of the sites. Acetaminophen had the highest median concentration (near 1 μg/L). Toulouse had the higher total pharmaceutical concentration, followed by Ghent, Benevento, Coimbra and Oslo. Contaminants from the European Union Watch List (ofloxacin, propranolol, fluoxetine) were detected. The pharmaceutical patterns differed among cities, except between Coimbra and Oslo. The contamination by pharmaceuticals, considering all sites, was predicted by population and tree cover densities, but also by morphological condition, riparian zone, water pollution and imperviousness within some of the cities. This study reveals a high contamination of urban streams by pharmaceuticals, which could lead to risks for the health of aquatic organisms and humans.