The soil fumigant 1,3-Dichloropropene (1,3-D) is used to control nematodes in high valued fruit and vegetable crops in the USA and globally, and is currently undergoing registration review at the USEPA. One of the conditions of the re-registration is to monitor 1,3-D concentrations in ambient air in high fumigant use areas for the purpose of estimating bystander exposure. Dow AgroScience has developed and validated a computer modeling framework (SOFEA3) to simulate 1,3-D concentrations in ambient air based on grower product use data. SOFEA3 predicts acute and chronic pesticide concentrations in air for large air sheds resulting from representative agronomic practices, and has recently been updated to include EPAs regulatory air dispersion model AERMOD. SOFEA3 is being used to simulate 1,3-D concentrations in four high fumigant demand areas in the USA, the Southwest, Pacific Northwest, mid-Atlantic coastal states, and the Southeast coastal plain. The model is parameterized with product use data including field location, treated field area, mass of 1,3-D applied and depth of application. Agronomic data are essential for characterizing the 1,3-D source strength in the model, and were obtained from growers in the defined study regions. Weather data for each region were obtained from state or federal meteorological stations. Modeled 1,3-D concentrations in high use areas in WA, NC and FL are consistent with the concentrations measured and modeled in ambient air in Merced, CA. The modeled short- and long-term 1,3-D concentrations in ambient air will be used to assess human exposure and risk.

SOFEA3 modeling of 1,3-dichloropropene concentrations in ambient air in high fumigant use areas of the United States

256th National Meeting (2018)

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