An innovative methodological path to attribute the hazard property HP14 "ecotoxic" to waste using a weight of evidence approach

The criteria for the application of hazard property code HP14 "ecotoxicity" to waste assessment have been defined by the Council Regulation (EU) 2017/997. However, on the basis of available methodologies, its application may present some issues. Those can be referred to the preparation and representativeness of the sample to be analyzed, to the chemical evaluation by the summation method (CLP Regulation), to the toxicity thresholds of ecotoxicological tests and the evaluation of the real environmental impact of waste. In this work an integrated chemical and ecotoxicological approach, that relies on modified synthetic indices previously developed for dredging sediment management is proposed. The methodological procedure, assuming that the eluate represents the most relevant carrier of contaminant into the environment, was applied on eluates extracted from samples of 3 kinds of waste categories (car-fluff, fly-ash and sludges), introducing changes starting from the sample preparation and the targeted ecotoxicological and chemical analyses. The application of this approach allowed qualifying the sludge and part of fly-ash samples as "non ecotoxic", unlike the conventional method (CLP) under which all waste categories considered were found to be "ecotoxic". The new pathway for waste qualification, abandoning the classical tabular approach based on mere chemical concentrations and/or predetermined thresholds of toxicity (principle of the worst case), showed a greater discriminatory power among samples with different characteristics, and a more realistic and quantitative assessment of the environmental impact which can be caused by leaching of the waste.