Comprehensive tracer studies on the environmental behavior of pesticides

Lysimeters using appropriate sizes and methodology has substantial potential to improve risk assessment. This potential for futural improvement of the basis for risk assessment includes, in addition to the assessment of the fate of pesticides in soils and groundwater contamination, comprehensive studies for effects on flora, fauna and mesofauna as well as effects in the aquifer. Major use of lysimeters at present practically is limited to fate and leaching investigations. In the fate assessments mostly concentrations are considered, but the loading concept - with respect to critical loads - may be a complementary alternative. Practical use of lysimeters in pesticides registration basically is following a realistic worst case scenario concept. Generic sets of scenarios considering data statistics and experimental uncertainties would provide improved bases for comprehensive risk assessments and for variations in time at one site, as well as for variations in time and space for regions. I n the following, examples are given for other uses of lysimeters. The examples include one concerning accumulation in soil from multiple applications, one on lysimeter toxicity testing to improve the information on the ecotoxicological potential of residues in soil and examples on indirect use of lysimeter data for the estimation of exposure in different regions (sensitivity of regions for pesticides leaching).