Incorporation of biomagnification in procedures for environmental risk assessment and standard setting

Abstract

Recently methods have been developed in the Netherlands to assess quality standards for the environment. Maximum permissible concentrations have been derived for direct exposure to environmental media. In 1991 two simple foodchains were analyzed at the RIVM. - Water --> Fish --> Fish-eating birds and/or mammals - Soil --> Worm --> Worm-eating birds and/or mammals. A general algorithm was provided to include secondary poisoning (exposure to contaminated food) in setting quality standards for the environment. The aim of this report is to give recommendations for future research and a concept for a more complicated terrestrial food chain: Soil --> Plant, worm, insect, etc. --> Small bird, small mammal --> Bird and beast of prey. A more precise description of the effects of compounds in the environment and of the factors influencing ecological and toxic effects are given. An overview of existing models dealing with biomagnification is presented. It is proposed to use a food web model based on aggregated groups of animals and plants. Since many species may be present within the system, e.g. plants, worms, insects, etc. and to a less extent in the group of small mammals and birds, it is proposed to aggregate the organisms in these levels in functional groups to reduce the complexity of the system. From this report it is apparent that the following correction factors for the toxicity data should be part of the model - laboratory versus field, - normal versus extreme conditions, caloric conversion, - food assimilation efficiency, pollutant assimilation efficiency and - relative sensitivity. It is recommended to use data from laboratory studies for building the model and to use field data for the validation of the model. Although it is possible to carry out the risk assessment with for instance constant bioaccumulation factors or other parameters, it is recommended also to consider these parameters as stochastic parameters.<br>