Due to different directives on the national and the European level it is necessary to analyse the fate of chemicals in the environment using exposure models. By combining the results of these models with ecotoxicity data the risk assessment is performed. Usually, this analysis is performed based on EUSES (EC (1996),EC (2003a)). It calculates the fate of chemicals based on generic scenarios. Generic scenarios do not represent real local situations, but reflect average situations for a given region, e.g. “the EU” or “Nordrhein-Westfalen”. The aim of the model is to estimate conservative concentrations for the different environmental  compartments in the respective region. In the year 2003 a new version of EUSES was released to consider the new version of the Technical Guidance Documents(EC (2003b)).