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In the context of the European legislation on chemicals (existing, new chemicals and biocides) a risk assessment for the environment and human health is performed. A technical guidance document (TGD), in support of Commission Directive 93/67/EEC on risk assessment for new notified substances and Commission Regulation (EC) No1488/64 on risk assessment for existing substances has been developed in 1996 and was recently adapted for the marine environment. The methodological concept is based on the relation between a value representing the contamination level of a chemical substance in the environment (exposure assessment) and a value representing its effects on the environment (effects assessment). The exposure value is expressed as PEC for "Predicted Environmental Concentration" and the effect value is defined as the PNEC, for "Predictive No effect Concentration". The risk characterisation is represented by the value of the PEC/PNEC ratio. The recent adaptation of the technical guidance document lead to two different aquatic assessments: one for the inland compartment and one for the marine compartment. This adaptation was conducted during two years and is the result of the co-operation of the European Commission and the OSPAR Convention. The main adaptations of the document to the marine environment concern the dilution rate in the water compartment, the behaviour of the substances, biodegradation, the local and regional exposure assessment scenario, effects assessment and secondary poisoning. A specific part dealing with PBT substances (Persistent, Bioaccumulable and Toxic) was also added. The initial concept of the guidance was however the same as for the inland environment. The document was used in the context of a specific study in France: "Environmental risk assessment of chemical releases of nuclear installations in Nord-Cotentin, France". The chemical releases of industrial sites were mainly composed of metals and a few organic chemicals. The releases of 27 substances in the marine environment were assessed. Limits and uncertainties of the methodology were underlined regarding, in particular, the determination of PNEC and the lack of ecotoxicological data for the marine environment., La législation européenne sur les produits chimiques (substances existantes, substances nouvelles, biocides) impose une évaluation du risque chimique afin d'assurer la protection de la santé humaine et celle de l'environnement.Un document guideméthodologique européen, appelé " Technical Guidance Document" (TGD) a été élaboré en 1996 pour permettre la mise en oeuvre d'une telle procédure qui soit commune à l'ensemble des États membres de l'Union européenne. Le concept méthodologique utilisé consiste à mettre en relation l'évaluation de la contamination du milieu, exprimée en concentration prévisible, baptisée PEC (" Predicted Environmental Concentration") et l'évaluation des effets, exprimée en terme de concentration prévisible sans effets, baptisée PNEC (" Predicted No-Effect Concentration"). La caractérisation du risque est basée sur la valeur du rapport PEC/PNEC. La révision du document guide européen a conduit à scinder la procédure d'évaluation du risque environnemental dans les milieux aquatiques en deux chapitres distincts, l'un concernant le milieu continental, le second spécifiquement le milieu marin. Ce travail d'adaptation du TGD au milieu marin a été mené durant deux ans dans le cadre d'une collaboration entre la Commission européenne et la Convention OSPAR. La première version de ce document constitue un document de référence pour l'évaluation du risque chimique en milieu marin. Sans remettre en question le concept méthodologique de base, les modifications apportées pour adapter le TGD au milieu marin concernent : le comportement des substances, la biodégradation, l'évaluation de l'exposition et les scénarios d'émission envisagés à l'échelle locale et régionale, l'évaluation des effets, l'évaluation de l'empoisonnement secondaire chez les prédateurs viale transfert trophique et la protection du milieu marin vis-à-vis des substances PBT (persistantes, bioaccumulables et toxiques). Dans le cadre de l'évaluation des risques environnementaux des rejets chimiques des installations nucléaires du Nord-Cotentin, cette méthodologie a été utilisée sur 27 substances parmi lesquelles quelques organiques et un grand nombre de métaux. Les premiers résultats de cette étude mettent en évidence les limites et les incertitudes de la méthode notamment dans la détermination des PNEC en milieu marin où les données écotoxicologiques sont faibles.

CLARA project ("Calculations Bound To Aquatic Spills in seawater") aims to develop an operational software that models the fate and effects of chemical substances when spilled accidentally into seawater. The marine risk assessment unit (ARC) contributes towards this project. ARC unit is in charge of the physico-chemical and ecotoxicological database of the model. During this project, Predicted No Effect Concentrations (PNECs) of 33 pure chemical substances have been determined to protect pelagic organisms living in estuarine and marine waters. Two types of PNECs were determined : PNECs based on short-term ecotoxicity data, within the context of accidental spills, and PNECs based on long-term ecotoxicity data. Bibliographic search was made as exhaustive as possible to collect ecotoxicity data for each substance. Then, methodological appraisal was carried out to validate or invalidate ecotoxicity data. Valid data were finally used to derive PNECs, according to hazard assessment principles within risk assessment method described in the Technical Guidance Document (EC, 2003). An obvious lack of marine ecotoxicity data for the 33 substances of concern in CLARA project has been underlined after examination.