• Validation of laboratory toxicity data on pesticides for the field situation

      Hamers T; Notenboom J; Eijsackers HJP; ECO; WAU (Wageningen Agricultural University WAU, 1996-01-31)
      A literature study has been performed in order to compare field and laboratory terrestrial toxicity data. Pesticides were chosen as group of chemicals under consideration because of the availability of relative many field data. The goal of this comparison was to validate the applicability of laboratory toxicity data. These are used for ecotoxicological risk assessment of new and existing chemicals and for the derivation of ecologically grounded soil quality criteria. Starting point of the validation was the hypothesis that responses under field and laboratory conditions are similar and comparable. Distinction was made between absolute and relative toxicity data. Absolute data were defined as absolute, quantified responses at known doses. Relative data were defined as ranks of responses, i.e. ranks for the sensitivity of multiple taxonomical groups to a single pesticide or ranks for the toxicity of multiple pesticides to a single taxonomical group. For both absolute and relative toxicity data, general trends were found between field and laboratory results. Therefore, it was concluded that the hypothesis should not be rejected. On the other hand, these trends were too weak to allow for a realistic prediction of a field effect based on a laboratory L(E)C50 or NOEC. This was due to a too large heterogeneity between different field studies which did not allow for a pooling of all field data. Moreover, due to a lack of field experiments with multiple field concentrations, it was impossible to compare dose-response curves from field and laboratory experiments adequately. To improve the statistical foundation of the laboratory-field validation, the following recommendations were made: (1) to improve tuning between the test designs of field and laboratory experiments, by studying similar soil types, pesticide formulations and distributions, concentration ranges, test species, environmental conditions, exposure times and routes of exposure ; (2) to improve the exposure analysis in field experiments by analyzing the actual field depositions and concentrations of contaminants ; (3) to determine dose-response relationships in the field by performing field studies with multiple doses.