Contamination of water with drugs - the response of phytoplankton

Human xenobiotic emissions exert a notable effect on aquatic organisms. However, there is a paucity of information concerning the chronic effects of drugs on aquatic microorganisms. Furthermore, the majority of studies to date have considered the toxicity of individual compounds in isolation rather than in complex mixtures found in the environment. The present investigation sought to assess the chronic impact of amoxicillin, bisoprolol, diclofenac, ketoprofen, sulfadiazine, and tramadol on three species of aquatic primary producers: Chlorella vulgaris, Desmodesmus armatus, and Trichormus variabilis for both individual compounds and their mixture. The obtained findings demonstrated significant inhibition of the growth of all tested strains, alteration in antioxidant enzyme activity, and morphological changes in their cells. The nature of the effects of the compounds in the tested mixture was additive. Furthermore, the ecological risk associated with exposure to the tested substances was assessed. The risk was determined to be high for ketoprofen and drugs mixture, medium for amoxicillin, diclofenac, and sulfadiazine, and low for bisoprolol and tramadol. The results of this study have revealed the ecotoxicological risks posed by the tested drugs to photosynthetic microorganisms, and have also offered insights into the biochemistry and cell morphology of the microorganisms in question. In addition, the findings of this study indicate that the exclusive reliance on the EC₅₀ parameter in the evaluation of the impact of xenobiotics on non-target organisms represents a remarkably constrained approach. This is attributable to the fact that it fails to provide insight into the changes that occur at the cellular level.