Maximum Permissible Concentrations (MPC's) for water and soil are derived for 46 volatile compounds. For 40 'inert' compounds MPC's for water are derived using an approach based on Quantitative Structure-Activity Relationshsips (QSAR's). By application of QSAR's NOEC values for 19 different organisms are obtained. This data-set is used as input form the extrapolation method of Aldenberg & Slob. For 6 specific acting compounds MPC's for water are derived using the more 'traditional approach. In this approach extrapolation methods are applied based on single species toxicity data. These data are obtained by an extensive literature search. In order to derive MPC's for soil the 'traditional' method is applied for all compounds because no QSAR's are available for terrestrial organisms. Only for 11 compounds a MPC can be derived because for the other compounds no toxicity data are available from literature.