Low concentrations of pharmaceuticals: action and reaction of freshwater invertebrates – Pharma_CARE

Pharma_CARE focuses on three compounds with psychotropic effects found in aquatic environments and with a high potential for biological effects: the antidepressants Sertraline and Paroxetine, and an antihistaminic drug Chlorphenamine. We will study the fate of these compounds within organisms (e.g. metabolism, tissue distribution, accumulation) after exposure to the compound alone or in mixture. We will also assess their biological effects via a multi-marker approach at different levels of biological organization, from molecular, individual and population effects to functional effects such as oxygen consumption.

The first key results at this stage are the strong inter-species differences in both the bioaccumulation of the pharmaceutical compounds of interest and the biological effects observed. Intra-species stress management, i.e. between males and females, was also highlighted, with males reacting more strongly to exposure. These differences are visible at all the scales studied. These results have been presented at national and international conferences.

The results of the Pharma_CARE project will provide new insights into the potential environmental impacts of compounds with psychotropic effects on freshwater ecosystems. 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.

Posters have been presented at various national and international conferences, and publications are in progress. These scientific productions cover the first results obtained on the impact of compounds with psychotropic effects on two species of freshwater bivalves of the Dreissena genus.

Currently, more than 3000 active ingredients (APIs) are used for medical and veterinary purposes. Of a very varied nature, they are logically detected in the environment, with the contamination of aquatic ecosystems now established worldwide. By definition, these APIs are biologically active at low doses, and their continuous release gives them a pseudo-persistent nature implying a chronic exposure of organisms. Despite the large amount of literature already published on their (eco)toxicity, many knowledge gaps still remain, especially about their long-term ecotoxicity at low concentrations and their mechanisms of action on non-target aquatic organisms. In this context, ionizable compounds at environmental pH, more easily bioaccumulated, are of particular interest. Recognising that it would unfeasible to monitor and assess all these compounds, it is necessary to identify those of most concern, and to test read-across hypotheses (RAH) to fill data gaps for the others. Chemical RAH implies that compounds belonging to the same therapeutic family and/or with similar chemical structures will induce the same biological effect. Similarly, the biological RAH states that compounds will induce similar biological effects across species if species if their molecular targets have been conserved. However, the validity of these hypotheses remains to be demonstrated for aquatic invertebrates that have most of these molecular targets but whose functional roles are not fully known.
The Pharma_CARE project aims to study the fate in organisms (accumulation, tissue distribution and metabolism) of APIs identified as priorities by several authors, as well as their chronic effects at environmental concentrations, in order to highlight similarities and differences in pharmacokinetic and pharmacodynamic properties between compounds (chemical RAH) and to test these properties in different molluscs (biological RAH). We propose to focus on 3 neuroendocrine disruptors: two antidepressants (sertraline and paroxetine) and an antihistamine (chlorphenamine, similar chemical structure to sertraline), and on 3 molluscs, key species in freshwater ecosystems but with different bioecological traits: 2 bivalves (Dreissena polymorpha and Dreissena rostriformis bugensis) and a gastropod (Limnaea stagnalis). The combination of non-targeted metabolome analyses by NMR and mass spectrometry will provide reliable information on the molecular effects of these APIs. In addition, a targeted set of biomarkers will be considered in relation to major physiological functions (e.g. neuroendocrine and immune systems, osmoregulation, energy metabolism), which may be disturbed according to available (pre)clinical information. The integration of metabolomic data and biomarker responses will provide a more comprehensive view of the health status of exposed organisms. The use of mass spectrometry imaging and LIBS, which are new in ecotoxicology, will also provide information on the tissue distribution of metabolites, APIs and inorganic elements. This information is essential for a better understanding of ecotoxicological mechanisms. This project, combining targeted and non-targeted approaches, will therefore provide fundamental and original data on (i) the modifications of metabolomic signatures and drug-response phenotypes induced by chronic exposure to these APIs, (ii) the mechanisms involved in the response of molluscs and the factors that influence them (e.g. seasons, bioecological traits). It will provide environmental managers and policy makers with information that can be directed towards hazard classification of APIs, their prioritising as well as risk assessments of impacts in contaminated environments.