Why have we not developed standards for sediments?

The standards developed for specific pollutants in water have been designed to be sufficiently protective of all aquatic compartments. This decision was taken because the availability of reliable toxicological data for sediment dwelling organisms is generally poor. In such cases the only basis for deriving standards in sediments is to use Partitioning Theory to predict the concentration. Most experts, including the EU Scientific Committee, consider the inherent inaccuracies of this approach to be unacceptably large. The EU Committee advised against its use for setting sediment standards for the priority substances.

UK Environment Agencies will continue to monitor water, sediment and/or biota where appropriate using the risk- based approach advocated in WFD. In some instances monitoring in sediment or biota may be more effective, for instance to illustrate trends, but the primary matrix for monitoring for compliance purposes will be water.