Modeling the implications of policy reforms on pesticide risk for Switzerland

Growing public awareness of the negative effects of pesticides on the environment, ecosystems, and human health has led governments to set targets for reducing pesticide risk. Switzerland introduced in 2023 two new policy measures to reduce pesticide risk by 50 % by 2027: (1) voluntary direct payment programs supporting pesticide -reduced and pesticide -free but non -organic cropping systems for most crops on arable land, and (2) restrictions of harmful pesticides for farmers managing under Swiss cross -compliance standards. This study aims to (1) develop a method to assess pesticide risk on a national scale and (2) carry out an ex -ante impact assessment to predict whether these policies can effectively reduce pesticide risks in Switzerland. Therefore, we introduced crop -specific pesticide quantities and pesticide risk scores into a sample of 1907 bio-economic farm optimization models. The models were used to predict farmers' adoption decisions regarding voluntary direct payment programs from 2019 to 2030. By combining the bio-economic farm optimization models with an agent -based modeling approach, we assessed the evolution of pesticide -related risks at the national level. Simulations for pesticide risk from 2019 to 2022 reflected the observed pesticide risk monitored by the Swiss government. In surface waters and semi -natural habitats, achieving the target depends on reducing pyrethroids, a class of insecticides with high -risk potential. Further, we highlight significant uncertainty in projecting the risk potential for surface waters and semi -natural habitats due to uncertainty about the amounts of pyrethroid used for different crops. The results underline the need for comprehensive datasets on pesticide use in Switzerland.