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Identification and compartmentalization study of emerging EDCs in an impacted river system by using an EDA approach
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Edité par CCSD -
The last decade dealt with the increasing occurrence of emerging pollutants (e.g. hormones, pharmaceuticals) that trigger adverse effects in river systems. Thus, strategies for their identification are needed. Effect directed analysis (EDA) approach aims at identifying such adverse chemicals. Its current use is the most often restricted to dioxin (AhR), estrogen (ER) or androgen (AR) receptors pathways while recent evidences suggested that others signalling pathways (e.g. PXR) involved in endocrine regulation can be disrupted. Hence identifying environmental active pollutants on these other pathways will enhance risk knowledge on endocrine disruption in situ. We report here the use of a battery of in vitro reporter gene bioassays including classical and emerging pathways to characterize the contamination of both sediment and surface water (polar organic integrative sampler (POCIS) and semi permeable membrane device (SPMD)). This allowed to integrate a wide range of active chemicals and to assess their distribution between river compartments. To isolate and identify these chemicals, a two-step fractionation was then used. This overall approach was applied to a river site under mixed anthropogenic pressure where fish are impacted. The bioassay profiling revealed estrogenic, anti-androgenic, dioxin-like and PXR-like activities in sediment while very strong estrogenic and PXR-like activities were measured in POCIS as regard to what reported scientific litterature. Bioanalysis of SPMD extracts is under progress. A first fractionation of sediment extract led to 4 fractions. F3 (polar) exerted only strong estrogenic and PXR-like activity while dioxin-like was mainly detected in F1 and F2. This demonstrated the occurrence of semi-polar to polar ligands of ER and PXR in sediments. Then F3 was hyperfractionated, estrogenic activity was mainly detected at the same elution time as BPA and 17beta-E2 while PXR-like activity was mainly detected in less polar fractions. In summary, this study demonstrates the usefullness of an EDA approach based on a multireceptors/ muti-compartment approach to assess and identify a diversity of EDCs and to study their distribution between water compartment The active fractions will be investigated using accurate mass spectrometric techniques while further fractionation strategies will be adressed on POCIS extracts. Purification on purified nuclear receptor column will be also tested on active fractionation for an optimized identification.
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