Conclusions of the workshop: harmonization of leaching/extraction tests for environmental risk assessment

Leaching/extraction tests are widely used for the assessment of the release of contaminants from different matrices, e.g., leaching tests for waste materials, single extractions for soil and compost materials and sequential extractions for sediments. Extraction procedures are also undertaken for evaluating plant uptake and the effects of landfill applications. In many instances, such schemes are included in national regulations or are considered in the framework of normalizing bodies such as CEN or ISO. If no efforts are made for harmonizing these procedures a multiplicity of tests will result. It is clear that this variety of schemes will not allow the data to be compared worldwide and will hence, create problems for the interpretation of data by the different regulatory bodies. Different groups of analysts (i.e., waste, compost, soil and sediment scientists) often follow radically different approaches, terminologies and data interpretations. Closer relationships between these groups would certainly encourage joint efforts for harmonizing these procedures which could, in some cases, be adapted for different matrices for a given purpose (e.g., assessment of release or soil fertility). At this stage, it was deemed necessary to discuss critically possible strategies to harmonize leaching and extraction schemes for environmental risk assessment and a workshop was held on 4 June, 1994, with participants covering different fields of expertise. The discussions allowed recommendations to be made regarding possible approaches to improve the present situation through, e.g., the creation of networks, interlaboratory studies prior to the adoption of standardized procedures, field validation of leaching/extraction schemes and production of reference materials certified for specified leaching/extraction conditions. This paper gives a summary of the round-table discussions. An outline of the programme along with the panel of experts participating in this workshop is given in the Appendix.