Bioavailability and biological effects of chemicals - Novel tools in risk assessment of mixtures in agricultural and contaminated soils

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The proposed strategic institute program focuses on emerging issues within terrestrial ecotoxicology that represent cutting edge research at the interface between environmental chemistry, toxicology and ecology. Pollutants released from industry and housh olds, as well as chemicals that are applied on agricultural sites to combat pests enter the soil as mixtures and represent an often unknown number of the 30,000 to 70,000 chemicals that are in daily use in Europe. However, authorities often use a chemical -by-chemical approach, focusing on a single media, a single source, and a single toxic endpoint to assess environmental risks. This program will therefore contribute in the development of methods for assessing the cumulative risks from combined exposures to multiple chemical stressors. What is more the program seeks to elucidate the the relationship between concentrations in soil, bioavailability for and effects on different kinds of soil living organisms. Insight in this relationship is considered as a prerequisite for understanding and modelling of the combined effect of mixtures is soil. Novel methods will be developed and evaluated that measure actual exposure of chemicals to soil organisms. By including bioavailability in exposure and effect assessm ent uncertainty in risk assessment will be reduced. An important subject of the institute program is the implementation of molecular techniques within the field of genomics in ecotoxicological research to investigate effects on diversity of soil fungi. Mo lecular techniques will also be used to unravel the mode of action of agricultural and industrial chemicals for relevant soil organisms.