CONCLUSIONS OF THE WORKSHOP - HARMONIZATION OF LEACHING EXTRACTION TESTS FOR ENVIRONMENTAL RISK ASSESSMENT

Leaching/extraction tests are widely used for the assessment of the re lease of contaminants from different matrices, e.g., leaching tests fo r waste materials, single extractions for soil and compost materials a nd sequential extractions for sediments. Extraction procedures are als o undertaken for evaluating plant uptake and the effects of landfill a pplications. In many instances, such schemes are included in national regulations or are considered in the framework of normalizing bodies s uch as CEN or ISO. If no efforts are made for harmonizing these proced ures a multiplicity of tests will result. It is clear that this variet y of schemes will not allow the data to be compared worldwide and will hence, create problems for the interpretation of data by the differen t regulatory bodies. Different groups of analysts (i.e., waste, compos t, soil and sediment scientists) often follow radically different appr oaches, terminologies and data interpretations. Closer relationships b etween these groups would certainly encourage joint efforts for harmon izing these procedures which could, in some cases, be adapted for diff erent matrices for a given purpose (e.g., assessment of release or soi l fertility). At this stage, it was deemed necessary to discuss critic ally possible strategies to harmonize leaching and extraction schemes for environmental risk assessment and a workshop was held on 4 June, 1 994, with participants covering different fields of expertise. The dis cussions allowed recommendations to be made regarding possible approac hes to improve the present situation through, e.g., the creation of ne tworks, interlaboratory studies prior to the adoption of standardized procedures, field validation of leaching/extraction schemes and produc tion of reference materials certified for specified leaching/extractio n conditions. This paper gives a summary of the round-table discussion s. An outline of the programme along with the panel of experts partici pating in this workshop is given in the Appendix.