| Popis: |
The impact of secondary poisoning on the Maximum Permissible Concentrations (MPCs) and Negligible Concentrations (NCs) of cadmium, copper and mercury in water, sediment and soil have been evaluated. Field data on accumulation of these elements by fish, mussels and earthworms were used to derive MPCs and NCs for birds and mammals for which these organisms are a food source. Accumulation by aquatic and terrestrial biota seems to be negatively correlated with external concentrations. The correlations lacked in strength and too few data on external concentrations for fish and mussels were available to draw conclusions. The scientific justification for using location-specific BCFs in the estimation of risk limits therefore still has to be established. Secondary poisoning of birds and mammals via fish or mussels may contribute to the risks of cadmium and mercury for the aquatic ecosystem. MPCs for copper in water derived with or without the inclusion of secondary poisoning are similar, although this conclusion is based on field data for mussels only. For the terrestrial compartment, inclusion of secondary poisoning does not lead to major changes in the MPCs for cadmium and copper. As toxicity data on soil organisms are hardly available, conclusions for mercury cannot be drawn. Further research into the accumulation of cadmium, copper and mercury by aquatic organisms is recommended. Data collection should include measurements in animals and water from the same location. For mercury, the determination of field BCFs should also include investigations into the relative contribution of methyl-mercury to the total mercury concentration in soil, water, sediment and animals living in these compartments. |
