From cells to organisms: an integrative assessment of pharmaceutical toxicity and mixture effects

Pharmaceuticals are ubiquitously detected in all environmental matrices and the continuous exposure of non-target aquatic species can impair their metabolic pathways, leading to unknown long-term effects. In this study, the ecotoxicological potential of 16 environmental pharmaceuticals and 7 mixtures (psychiatric, cardiovascular, lipid-lowering, non-steroidal antinflammatory drugs, and antidiabetics) were evaluated in 6 different biological models. In vivo ecotoxicological bioassays (algal growth inhibition, oyster and sea urchin embryotoxicity, bacterial bioluminescence inhibition) were combined to in vitro tests on fish hepatic (PLHC-1) and gill (RTgill-W1) cell lines. A quantitative Weight of Evidence approach was applied to better compare the biological significance of all tested experimental conditions. Results on ecotoxicological bioassays demonstrated different sensitivity of the tested species, with higher effects observed in terms of embryotoxicity and/or algal growth inhibition. Among cell lines, PLHC-1 exhibited selective toxicity towards specific active principles, whereas RTgill-W1 showed broader susceptibility. Psychiatric drugs were the most reactive therapeutic class in all biological models, whereas atenolol, naproxen, paroxetine, venlafaxine and carbamazepine-10,11-epoxide exhibited the greatest toxicity among all investigated compounds. Despite this study did not support a formal mixture-toxicity framework, mixture responses varied among combinations and models, and composition appeared more important than mixture size under the tested conditions. Overall, the selected biological models exhibited distinct species-specific response patterns following mixture exposure. By integrating measured effects into synthetic hazard indices, the quantitative Weight of Evidence approach demonstrated the potential of effect-based tools to prioritize future studies on environmental pharmaceuticals.