In this report Maximum Permissible Concentrations (MPC) are derived for 9 trace metals based on ecotoxicological data. The elements are: antimony, barium, beryllium, cobalt, molybdenum, selenium, thallium, tin, and vanadium The study was carried out in the framework of the project "Setting integrated environmental quality objectives". For the aquatic environment MPCs could be derived for all trace elements. These values were based on toxicity data for freshwater as well as saltwater organisms. Also a comparison was made between the sensitivity of saltwater and freshwater organisms for these trace elements and some other metals. The conclusion could be drawn that in acute tests freshwater and saltwater organisms are equally sensitive but that freshwater organisms are more sensitive in chronic tests. It should be stated however that much more data were available for freshwater organisms. For the soil only for cobalt a MPC could be derived. For the other trace elements no reliable toxicity data were available. For sediment dwelling organisms no MPC could be derived because no toxicity data were available for benthic organisms exposed via the sediment. Secondary poisoning was taken into account for the routes water --> fish --> fish-eating bird or mammal and soil --> earth-worm --> worm-eating bird or mammal. A 'screening-method was used in which only information from reviews was used. Only for thallium and selenium data were available for the aquatic route. From these data it could be concluded that there was no risk for secondary poisoning for these metals.