Influence of leaching conditions for ecotoxicological classification of ash

•All investigated leaching conditions significantly influenced the toxic potential.•H-14 classification should include leaching and ecotoxicological testing.•Leaching conditions is a crucial task to consider in deciding H-14 classification. The Waste Framework Directive (WFD; 2008/98/EC) states that classification of hazardous ecotoxicological properties of wastes (i.e. criteria H-14), should be based on the Community legislation on chemicals (i.e. CLP Regulation 1272/2008). However, harmonizing the waste and chemical classification may involve drastic changes related to choice of leaching tests as compared to e.g. the current European standard for ecotoxic characterization of waste (CEN 14735). The primary aim of the present study was therefore to evaluate the influence of leaching conditions, i.e. pH (inherent pH (∼10), and 7), liquid to solid (L/S) ratio (10 and 1000L/kg) and particle size (