Can we easily read-across in ecotoxicity data ? A case study with two dreissenid species exposed to three psychotropic drugs
Résumé
Pharmaceuticals are a large family of organic compounds, widely distributed worldwide due to medical and veterinary uses. All these compounds in their original form, as well as their metabolites and degradation products, are considered as "contaminants of emerging concern", with still knowledge to acquire on their fate and effects on non-target aquatic organisms. Knowing more about the ecotoxicity of pharmaceuticals will allow environmental risk assessments to be improved, predictive modelling to be refine, and more focused management measures to be developed and implemented. Identifying approaches to read-across pharmaceutical safety information to non-target species represents a major research need to assess environmental hazards. The objective of our work is to compare the effects of three psychotropic compounds, either of the same therapeutic family or of similar chemical structure (i.e. testing of the “chemical read-across” approach), on two freshwater bivalves, Dreissena polymorpha and Dreissena rostriformis bugensis (i.e. testing of the “biological read-across” approach). Bivalves will be exposed for 14 days to sertraline, paroxetine (two antidepressants) and chlorphenamine (an antihistamine drug with similar chemical structure as sertraline) alone at two concentrations (0.5 and 5 µg/L). Mixture effects were also assessed. A targeted set of biomarkers will be studied, linked to important physiological functions, related to the neuroendocrine system, antioxidant defences, and energy metabolism, as well as proxys of bivalve’s ecological roles (filtration, oxygen consumption and mineral contents). Potential differences between males and females will also be assessed. Differences in the biological responses of the two species and the two sexes are likely, but similarities between the effects of the three compounds on the targeted biological functions can be expected. This ongoing work will determine the sizes of these differences and effects. Since the two dreissenid species are also invasive species, our work will also provide key elements in the understanding of the defence mechanisms of the two dreissenid species, that could be a relevant way to better predict their invasion dynamics.