Abstract

The study in this report was carried out in the frame of the project "Evaluation system for new chemical substances". The aim of the study was to present a general algorithm for risk-assessment on secondary poisoning of birds and mammals. Risk-assessment on secondary poisoning can be an asset to risk-assessment on direct poisoning in setting quality standards for the environment. The water - fish - fish-eating bird or mammal pathway was analyzed as an example of a secondary poisoning pathway. Parameters used for the algorithm are the bioconcentration factor for fish (BCF) and the no-observed effect concentration for the group of fish-eating birds and mammals (NOEC fish- eater). For the derivation of reliable BCF's preference is given to the use of experimentally derived BCF's over QSAR estimates. NOEC's for fish-eaters are dervied by extrapolating toxicity data on single species. Because, data on fish-eating species are seldom available, toxocity data on all bird and mammalian species were used. The proposed algorithm (MTR = NOEC fish-eater / BCF) was used to calculate maximum tolerable risk levels (MTR's) for the compounds: lindane, dieldrin, cadmium, mercury, PCB153 and PCB118. It was concluded that for mercury and dieldrin secondary poisoning of fish-eating birds and mammals can occur at levels in surface water below the MTR calculated by risk-assessment for aquatic organisms. Secondary poisoning of fish- eating birds and mammals is not likely to occur for cadmium at levels in water below the MTR calculated for aquatic organisms.