... a procedure called COMMPS (combined monitoring-based and modelling-based priority setting) has been elaborated in collaboration with a consultant (Fraunhofer Institute for Environmental Chemistry and Ecotoxicology, Germany herein simply referred to as the Fraunhofer Institute). The basic idea is to rank substances for which sufficient data are available according to their relative risk to the aquatic environment in an automated manner and to apply expert judgement for the final selection of priority substances. ... The revised Fraunhofer study exploited about 750,000 surface water monitoring data items and about 70,000 sediments monitoring data items. Data were provided by all 15 Member States and by the European Union of National Associations of Water Suppliers and Waste Water Services (EUREAU). Modelling data were provided by the European Chemicals Bureau and are therefore fully compatible with the database used for the prioritisation of existing substances.