Fungicidas usados en cereales de invierno y su potencial riesgo en el ambiente

Winter cereals in Uruguay, particularly wheat and barley, are highly important crops. Their yield and quality can be affected by diseases, with the primary management strategy being the use of foliar fungicides. However, these fungicides may have unintended impacts on non-target organisms and environmental compartments. The objective of this study was to identify the potential environmental risks associated with fungicide applications in Uruguay for disease control in wheat and barley. The specific goals were to assess exposure, hazard, and environmental risk at a national level and estimate these risks in four farms located in the country's main winter cereal-producing region. To evaluate the potential risk, active ingredients were selected based on data from INIA and the DGSA. Their physicochemical properties were analyzed to characterize exposure. The hazard was assessed by examining toxicity in species from soil, water, and air compartments, using data provided by the Pesticide Properties Database from the Agriculture & Environment Research Unit. In the selected farms, Toxic Units (TU) were calculated for terrestrial, aquatic, and aerial organisms during the 2021/2022, 2022/2023, and 2023/2024 seasons, identifying which scenario presented the highest potential risk. Of the active ingredients studied, 14% showed a high probability of persisting in the soil compartment, influenced by their composition. These conditions, combined with predisposing climatic factors, determine the environmental impact by affecting fungicide degradation and transfer to other compartments. As a result, 39% could be found in both soil and/or aquatic environments, while 14% were specifically identified in the aquatic compartment. The remaining 32% were likely to degrade in either environment. Regarding hazard characterization, the potential toxicological effects on mammals, earthworms, birds, bees, fish, invertebrates, and algae were determined. In terms of the farm study, the one that planted wheat and barley across all seasons, with the highest number of applications and doses, exhibited the greatest potential risk to all studied organisms. This study enabled the characterization of the hazard and environmental fate of fungicides used for disease control in winter cereals in Uruguay. The results highlight the need to intensify efforts to thoroughly characterize exposure, allowing for better risk estimation and the adoption of sustainable practices and/or mitigation measures.