On 31 Janury 2012, the European Commission published its proposal for the revision of Directives 2000/60/EG and 2008/105/EG regarding priority substances in the field of water policy. In this proposal, the current list of priority substances is supplemented with 15 new substances. Also, for 4 existing substances tightened environmental quality standards are proposed. A comprehensive (re)assessment of the priority substances list preceded this proposal. It concerns the following groups of substances: Plant protection product substances, Substances used in biocidal products, Industrial chemicals, Combustion by-products, Pharmaceutical substances.