The preparatory work for the list of priority substances took place over two years and involved the development of an advanced priority setting method and collecting and evaluating extensive data sets. A study project was commissioned by the DG Environment in co-operation with the German Federal Environment Agency. In addition, a expert advisory group consisting of experts from Member State, EFTA countries, the Scientific Committee of Eco-Toxicity, Toxicity and the Environment (SCTEE), the European Chemicals Bureau and stakeholders from industry, water suppliers and environmental groups met in early 1998 for the first time to discuss an advanced methodology for the priority setting of substances dangerous to the aquatic environment.
A combined monitoring-based and modelling-based priority setting (COMMPS) procedure was developed. In the application of the COMMPS procedure about 820 000 monitoring data from waters and sediments from all Member States were evaluated and data for more than 310 substances on production, use and distribution in the environment were used for modelling if the available monitoring information was insufficient. The consultant presented a first draft in July 1998 and a revised draft final version in April 1999. After reviewing the quality and the statistical assessment of the data it was recognised by all involved parties that the COMMPS procedure was scientifically sound and the proposal from the consultant formed a good basis for first proposal under the Water Framework Directive. The Commission invited all parties in the expert advisory meeting to send comments. In preparing the final Commission proposal these comments were taken into account leading to some changes in relation to the proposal by the consultant.
The final COMMPS report "Study on the prioritisation of substances dangerous to the aquatic environment"can be ordered. The main part "Revised proposal for a list of priority substances in the context of the water framework directive (COMMPS procedure)" can downloaded as a PDF files (Report - 480K; Annex - 880K).
The Commission proposed a procedure for the identification of priority hazardous substances outlined in the Working Document (ENV/191000/01 of 16 January 2001). The proposed procedure in the Working Document groups the proposed 32 priority substances according to their "level of concern" taking particular account of their "level of hazard". The procedure is based on the best available knowledge. The main emphasis was put on available "hazard assessments", in particular work carried out under the OSPAR Strategy with regard to Hazardous Substances, the classification and labelling of dangerous substances under Council Directive 67/548/EEC and the Protocol on POPs under the UN-ECE Convention on Long-Range Transboundary Air Pollution. Furthermore, the procedure considered the finalised risk assessments made under Council Regulation (EEC) No. 793/93 and Council Directive 91/414/EEC and the information under the regulations of pollution by certain dangerous substances discharged into the aquatic environment under Council Directive 76/464/EEC and its five 'daughter' directives. The above-mentioned information was used to group the priority substances into clusters with increasing "levels of concern".
For the final assignment of a priority substance, "additional considerations" were considered to confirm or reject the status of the substance. The "additional considerations" included other relevant Community legislation or relevant international agreements, the production and use of the substance, the socio-economic impacts of a cessation or phase-out and the suspected endocrine disrupting potential of the substance. The final qualitative assessment of the socio-economic costs related to the identification of substances for inclusion as priority hazardous substances was carried out in the study "Socio-Economic Impacts of the Identification of Priority Hazardous Substances under the Water Framework Directive", conducted by RPA December 2000 (Report).