A modelling approach for the prioritization of chemicals under the water framework directive

This is the report of a feasibility study in which a model-based prioritisation methodology was developed in support of the implementation of the Water Framework Directive. The approach focuses on aquatic ecosystems and takes into account the intrinsic hazards of chemicals as well as their exposure levels.. The prioritisation approach also takes into account hazards due to secondary poisoning, bioaccumulation through the food chain and potential human health effects, e.g. due to consumption of fish or drinking water. A list comprising 2034 compounds provided by Member States, Stakeholders and Non-Governmental Organisations was evaluated according to pre-defined hazard and exposure criteria. Then 78 compounds considered to be “of high concern” were analysed and ranked in terms of their PEC/PNEC risk ratio (Predicted Environmental Concentration/Predicted No-Effect Concentration). In the interests of reproducibility, the tools employed in a model-based prioritisation process should ideally be freely accessible; however in this study this was not entirely possible due to the tight schedule and the fact that some estimation/calculation procedures were not available and thus needed to be developed. Nevertheless, the proposed approach constitutes a first step in for the establishment of an open modular tool that could eventually be used to support future prioritisation exercises.