Fumigant Emission Physical Factors and Measures for Mitigating Exposure Incidences

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the U.S. Environmental Protection Agency (EPA) evaluates and periodically re-evaluates the potential risks of pesticides to humans, wildlife, and plants. In its evaluation or registration process, EPA may develop precautionary labeling language for pesticide products to reduce potential risks to human health and the environment. The Agency also considers other exposure mitigation measures such as buffer zones for chemicals that have the potential to drift, run off, or leach onto land or water bodies.

For fumigant pesticides, the major exposure pathway is volatilization. Understanding the volatilization process for fumigants is therefore key for reducing potential exposure to bystanders and non-target organisms. In this presentation, the author will discuss factors that influence the onset of volatilization such as surface boundary conditions and atmospheric factors, including temperature inversions. In addition, the state of the science and the feasibility of utilizing currently available tools to support situational mitigation measures will be examined. Currently, these tools include the National Weather Service warnings, which are based on numerical weather prediction models (i.e., MM5, WRF, NAM, or GFS), and regional airshed forecasting programs.