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(M/EH068) Assessment of the environmental properties and effects of pesticide degradation products. Boxall, Alistair1, Beulke, Sabine1, Chen, Beining2, Norman, Steve3, 1 2 3 ABSTRACT- When released to the environment, pesticides may be degraded by micro-organisms and/or chemical processes. Under EU Directive 91/414/EEC, the environmental impact of selected pesticide transformation products needs to be assessed. Currently, the only approach to assessing the fate and effects of degradation products is to perform experimental studies (e.g. LC50 fish studies) on the compound(s) of interest. This is a drain on resources in terms of both cost and time. A more pragmatic approach could therefore be extremely useful, that could be used at lower tiers of the risk assessment process, the results acting as a trigger for future work. One possible alternative approach is to use data on the properties, fate and ecotoxicity of the parent compound along with modelling approaches to predict the environmental fate and effects of degradation products. A range of possible techniques is available, including: a) qualitative assessments of the metabolite molecule to assess pesticidal activity; b) the use of structure-property, structure-degradability and structure-activity relationships; c) a consideration of the relative uptake of the metabolite compared to the parent compound. This study, funded by the UK Ministry of Agriculture Fisheries and Food, is therefore being performed to assess the suitability of these different approaches. A framework has been developed for assessment of metabolites, combining experimental testing with predictive methods. This framework has been assessed using available data in the literature on the properties, ecotoxicity and fate of metabolites. Comparisons of predictions with available experimental data will be presented. It is hoped that additional data will be provided by the pesticide industry in the near future to allow a complete validation of the approaches. The results of the project will feed into discussions at the EU level. It is anticipated that the approaches could be used in the future to determine a) whether a particular transformation is a possible relevant metabolite; and b) if it is potentially relevant, what the most appropriate testing strategy would be. Key words: metabolite, QSAR, pesticide |
