Values are derived which can be used to set integrated environmental quality objectives (limit and target values) for 25 compounds with a potential for secondary poisoning. First, Maximum Permissible Concentrations (MPs) and Negligible Concentrations (NCs) are derived for water, sediment and soil based on direct effects on aquatic and soil organisms using extrapolation methods and on possible adverse effects due to secondary poisoning. Two foodchains are taken into account: an aquatic route (water --> fish or mussel --> fish- or mussel-eating bird or mammal), and a terrestrial route (soil --> earthworm --> worm-eating bird or mammal). Thereafter MPCs and NCs are harmonized using the equilibrium partitioning method. Secondary poisoning may be critical via the aquatic route for the following compounds: aldrin, cadmium DDT and derivates, dieldrin, endrin, all HCH isomers, penta- and hexachlorobenzene and methyl-mercury. For heptachlor, heptachlor epoxide and quintozene toxicity data for aquatic organisms as well as birds and mammals are too scarce to draw conclusions. Via the terrestrial route secondary poisoning may by critical for cadmium, copper, penta- and hexachlorobenzene and methyl-mecury. Due to scarcity of data (effects on soil organisms as well as toxicity data for birds and mammals) these results should be treated with caution. Also the method for assessing effects due to secondary poisoning via the terrestrial food-chain has several important limitations. The method applied in the present report to incorporate effects due to secondary poisoning is considered a first screening. For those compounds for which these effects may be critical more research is necessary, of which obtaining local and species specific information from field studies is most important.