Advancing emission and impact modeling for agricultural pesticides under tropical conditions, to improve scientific foundation of the environmental evaluation of tropical agri-food systems

The use of pesticides in agriculture leads to environmental and human health impacts, particularly in tropical regions where pedoclimatic conditions favorable to pests and diseases, encourage their use all year round. Life Cycle Assessment (LCA), an ISO-standardized methodology is widely applied to quantify the environmental performance of agri-food systems but generally do not account properly for impacts due to pesticide applications. A bibliographic review identified the characteristics that determine pesticide emissions and related impacts under tropical conditions, and assessed to what extent Life Cycle Inventory (LCI) and Life Cycle Impact Assessment (LCIA) models need to be adapted to better account for these conditions. The main goal of the thesis was to advance emission and impact modeling for agricultural pesticides under tropical conditions for improving scientific foundation of the environmental evaluation of tropical agri-food systems. First, we identified with a sensitivity analysis on the pesticide emission model PestLCI Consensus, aspects that needed be developed in priority. Then, the initial emission distribution was refined by developing a consistent set of foliar interception fractions as function of crop characteristics and spraying techniques for crops grown under tropical conditions. In addition, based on a literature review, measures of drift from application methods were extracted from experimentations specifically conducted in tropical conditions. Thanks to these developments, a consistent set of pesticide emission fractions were provided for direct use by LCA practitioners. A consistent coupling of pesticide LCI-LCIA models was proposed for all agricultural contexts including human toxicity due to exposure to pesticide residues in crops. The proposition was tested successfully on an LCA of an open-field tomato produced in Martinique (French West Indies) by parametrizing the model to the local conditions. Moreover, to evaluate the environmental sustainability of agricultural practices a framework was proposed to account for ground cover management in the modeling of pesticide emissions. These methodological, scientific and operational advances constitute an important step toward a more reliable modeling of field pesticide emissions, including emission to the consumed part of the crop, and their consistent conversion into (eco)-toxicity impacts, as part of LCA for agri-food systems in tropical regions. To improve further the assessment of agricultural pesticides in LCA, especially for tropical conditions, a better consideration of rain-related processes in pesticide emission model is needed.