12 Concluding remarks

Abstract

This chapter demonstrates that to perform the external cost assessment in as complete a way as possible, the work has to be developed and applied an extension of the impact pathway approach (IPA) termed WATSON (integrated WATer and SOil environmental fate, exposure and impact assessment model of Noxious substances). WATSON facilitates the coverage of exposures toward hazardous substances released into air, (fresh) water and soil through ingestion of various food items in a spatially-resolved pan-European setting. The approach comprises several special features that shall be recapitulated in the following includes the overall method relies on a coupled set of environmental fate models for air on the one hand and for soil and (fresh) water on the other. While the assessment for air has been adopted from the existing software tool EcoSense (European Commission, 2003d), the contaminants’ environmental fate in the terrestrial and aquatic environment is described with the help of a spatially-resolved climatological box model similar to Mackay level III/IV models (Mackay, 1991). Both fate models assume long-term average conditions for the description of the environment. In line with current political concern, the focus is laid on persistent substances such as heavy metals. In particular, the trace elements arsenic, cadmium, chromium and lead are investigated. The methodological development has, therefore, focused on this substance group that had been poorly addressed previously in the realm of multimedia modeling.