Ecotoxicological testing of waste materials: State of the art and future developments

In the European Union, the hazard properties of wastes have to be determined according to the Commission Regulation (EU) N° 1357/2014. However, this document does not specify how the HP 14 property (Ecotoxic) has to be tested and assessed. In fact, there are two, approaches for this task: 1. Evaluation according to the CLP-approach, which defines the rules for the classification of chemical mixtures. In that case, the hazard of a waste is calculated according to its chemical composition, based on summation of classified components. The main problem of such an approach is that waste samples usually contain many, often unknown chemicals. 2. Ecotoxicological testing of waste samples, using standard ISO methods originally developed for the assessment of contaminated water or soils. An early version of this approach has successfully been used in an international ringtest. Recently, a strategy that combines both approaches described above has been proposed. The waste assessment starts with the evaluation of existing information on the chemical composition and the summation method is carried out according to the CLP regulation. If sufficient data on the composition are available the assessment can be finalized after this step. Also when the waste is already classified based on partial data, no further assessment is needed. In all other cases ecotoxicological tests have to be performed. First an assessment of the ecotoxicity of the waste eluates using aquatic tests, has to be done. If the waste sample is not classified as hazardous based on its aquatic toxicity, the ecotoxicity of the solid waste material is tested using terrestrial tests. The waste is classified as hazardous or non-hazardous when limit values for hazardous chemicals (in step 1) of for toxicity (in steps 2 and 3) are exceeded or not. Based on experiences of 20 years of waste testing, a test battery has been selected, consisting of three aquatic and three terrestrial tests (per compartment one microbial, one plant and one invertebrate species). Using the approach described so far and using examples from our own research in France, Germany and Belgium we will show that this strategy of combining an initial CLP-classification with ecotoxicological tests as a second step is scientifically sound, practical and easy to perform. However, open research questions still remain (e.g. the identification of threshold values, or the consistency of this assessment with the List of Waste)