Impacts of Pesticide Leaching in an LCA on the product development of pesticides.

Geisler G., S. Hellweg, and K. Hungerbuehler, Swiss Federal Institute of Technology, Zurich, Switzerland.

To include a life cycle perspecitve in the product development of pesticides, LCA is a suitable method. The LCIA of the use phase of the pesticide should consider the exposure of humans and ecosystems due to the leaching of pesticides to groundwater. Many site-, use- and substance specific factors influence these complex exposure pathways. In this study, the variability of exposure due to the leaching of pesticides to groundwater was assessed. An event tree was set up to determine scenarios of maximum and minimum exposure. This event tree is parametrised specifically for a given crop. For each scenario derived from the event tree, the mass of pesticide leached to 1 m depth in a field of 1 ha was simulated. We used the FOCUS-groundwater modelling framework for these calculations. The FOCUS-methodology, initially developed for Risk Assessment in the EU pesticide registration, ensured realistic and consistent model settings in all scenarios. The variability of the scenarios ranged from no leaching at all to leaching of around 5 % of the applied substance in worst cases, when substance properties, weather and soil type combined to favour the leaching of a pesticide. The scenario outcomes were underpinned by a literature review of field studies on pesticide leaching. Further, the fate of pesticides in the subsoil below 1 m and in the groundwater was and the exposure of humans and ecosystems were estimated. These scores can be used as a mid-point indicator in LCIA. The integration of the exposure scores into existing LCIA-methods is discussed. The leaching assessment is applied to a case-study of a pesticide life cycle, taking the perspective of a developer of pesticide active ingredients.