Proposed development of Sediment Quality Guidelines under the European Water Framework Directive: a critique.

The Water Framework Directive is the most important piece of water legislation in Europe for many years and will substantially influence the environmental regulation of chemicals, including human and veterinary pharmaceuticals. The development of Sediment Environmental Quality Standards (EQSs) is called for by the Directive, and proposals have been made for achieving this. However, these proposals are technically controversial and could have considerable logistical consequences. This paper describes the background to the Directive and lists questions that must be answered before Sediment EQS derivation is undertaken. Possible answers to these questions are then provided. The main problems with current proposals to the EC are that mandatory 'pass/fail' standards assume that approaches for setting sediment standards are more reliable than is the case, and that suspended sediments are a more appropriate sampling medium than settled sediments for assessing the general risk of sediment-bound chemicals to wildlife.