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.
