Fumigants escaped from soil to air after applications may cause exposure in humans including applicators and bystanders, and the exposure levels may be proportional to fumigant emission rates. To that end, the Exposure Assessment Section of the California Department of Pesticide Regulation use field monitoring studies to determine the fumigant emission rates for assessing both occupational and residential bystander exposures. Specifically, this analysis reviewed emission studies of the five most commonly used fumigants in California: 1,3-dichloropropene, chloropicrin, methyl bromide, metam-sodium and potassium N-methyldithiocarbamate. These studies were grouped into different categories depending on their application (e.g., broadcast shank) and tarp methods (e.g., totally impermeable film). The corresponding study reports were reviewed for data completeness, quality and usability for human exposure assessment. This analysis found that different fumigants exhibit different emission patterns over time, and for each fumigant examined, the highest emission did not always occur on the first day after the application. Application and tarp methods also influenced the emission rates. In addition, time-weighted averages of the measured emission rates were calculated and could be used in air dispersion modeling and bystander exposure assessment. This review summarizes current knowledge on fumigant field emissions, and can serve as surrogate data when emission information for a particular fumigant is not available. Results of this analysis also yielded several suggestions that may be considered in future field emission studies to improve the data usability for human exposure assessment.

Review of fumigant field emission studies for human exposure assessment

2019 Fall National Meeting

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