Mapping temporal trends of pesticide use and identifying potential non-occupation population exposure using a...

Estimating pesticide exposure in environmental settings is complex due to limited data, evolving agricultural practices, and increasing use driven by weed resistance and genetically engineered crops. One of the most widely used herbicides, 2,4-D, is a concern for populations near agricultural fields due to its rapidly increasing use. We used a geospatial approach to show spatio-temporal trends of pesticide use and identify at-risk populations for non-occupational pesticide exposure. 2,4-D application on soybeans in Illinois during the years 2017, 2020 and 2023 were used. We calculated the rate of change on the county level using reported 2,4-D use and soybean crop area. Then we created a crop area, pesticide density buffer model using 1 km buffer zones correlated with 1000 m x 1000 m gridded census data to identify where populations were at risk of non-occupational exposure in Champaign County. Between 2017 and 2023, there was a median increase of 341% in 2,4-D application on soybeans in each county in Illinois. We found that 98.9-99.7% of the population of Champaign County lived within 1 km of at least 0.04 km² (10 acres) of soybean crops from 2017 to 2023. Using 4.4 kg of 2,4-D as a threshold within the 1 km buffer zone, 24.5% of the population was potentially exposed in 2017, this increased to 44.5% of the population in 2023. In 2017, the area where the most 2,4-D (30 kg) was applied to soybean crops represented 0.01% (14 people) of the population potentially exposed. Using 30 kg as a reference point, in 2023, 20.2% (~ 47,000 people) of the population were at potential risk of this level of exposure. Previous research has shown increasing 2,4-D agricultural use has been associated with increased 2,4-D physiological levels. We mapped at-risk populations for 2,4-D exposure due to 2,4-D application on soybeans that has increased from 2017 to 2023 using GIS. This is a cost-effective method that identifies areas to focus further studies.