Published Date: 11/12/2002
Sewage sludges contain organic chemical contaminants from a variety of sources and at low concentrations. The European Union has proposed that limit values, relating to the application of sewage sludge to agricultural land, are established for some specific classes of compounds. This report presents a critical evaluation of the proposed EU limit values, examining how and why the standards have been derived, considering whether they are scientifically defensible, and the practical implications of trying to implement them. It is shown that the derivation of the proposed limit values has little scientific credibility. Further, it is shown that if the proposed limits are adopted for some chemical classes, the 'sludge-to-land' outlet will be seriously impacted, with little or no benefit to the quality of soils, crops and human exposure to the chemicals in question. The report presents a logical, step-wise approach for considering the fate, behaviour and significance of organic chemical contaminants in sludge-soil-foodchain transfer scenarios, which can be used to help derive scientifically defensible limits.