The evaluation of the hazardous nature of a waste is frequently based on total composition in many jurisdictions, while for most cases the chemical form of the constituents and the release pathways that may result in exposure of man and organisms under conditions of handling, transport, disposal or beneficial use are the most important factors controlling potential environmental impact. Thus, leaching assessment related to possible management scenarios rather than total content can provide a much more robust basis for evaluating health risks and environmental risks for waterborne pathways. Standardized characterisation leaching tests based on intrinsic characteristics of a material provide a new foundation for needed decisions. Chemical speciation modelling using characterisation testing results provides a means to identify mechanisms controlling constituent release, including mineral or sorptive phases, and thus insights into the long-term release behaviour of the material and approaches to reducing potential impacts. (C) 2011 Elsevier B.V. All rights reserved.