Détermination de Valeurs Guides Environnementales (VGE) mollusques alternatives aux Normes de Qualité Environnementale (NQE) définies dans la DCE

The Water Framework Directive (DCE 2000/60/CE), aims to achieve the good conditions (chemical and ecological) of different waters in Europe. The Environmental Quality Standards (EQS) are the tools used to evaluate the chemical condition waters. Initially, the EQS are defined for the water matrix, but with the analytical difficulties and low spatial and temporal representativity of water samples, the monitoring of contaminants must be carried out on alternative matrices, as mollusks and particularly the mussels. Among the 45 priority and dangerous priority substances establishes by the WFD 2013/39/UE, 25 substances are hydrophobic and bioaccumulable. The main goal of this study is to determine thresholds applicable in the mussels at least as protective as EQS in marine water. For it, the study takes place in three steps. First, the state of knowledge about the relations between the concentrations of contaminants in the marine water and mussels is realized through the description of bioconcentration factor (BCF) and bioaccumulation factor (BAF). There are several methods to determine available BCF or BAF: the BCF can be defined by experimental method or using Quantitative Activity-Structure Relationship (QSAR) models. The BAF can be determined in the field, in laboratory, by modelisation or using QSAR models. Second, a literature review is conducted to identify concentrations of contaminants data in the waters on metropolitan French coast (Cwater), and compare them with concentrations in mussels (Cmussels) obtained through French monitoring network (ROCCH and RINBIO), to determine field BAF (Cmussels /Cwater). In parallel, valid BCF were also determined according to different methods: experimental method and calculation by QSAR. Where possible, a comparison between BAF and BCF values was realized. The third step allows to list the results obtained for BCF or BAF for the 25 substances studied, and if necessary to propose the selection criteria, to set the value to remember. This value will be retained to determine the corresponding thresholds applicable to mollusks. This study allows to propose the thresholds for 23 of the 25 substances studied. It also highlights the need to define a methodology for the acquisition of available BAF and the lack of data to compare the concentrations in water and in mussels for the same substance.