Exposure, Risk Assessment and Predictive Exposure Model Development for Agricultural Operator in Representative Crop Fields

Abstract

Korea predictive model for the estimation of agricultural operator exposure has been developed on the basis of new exposure data to improve the current agricultural operator exposure and risk assessment in the Korea. The new operator exposure model represents current application techniques (speed sprayer and power sprayer) and practices in representative crop fields (apple orchard and rice field). 30 replicate exposure studies conducted between 2010 and 2012 were evaluated for the new model. Exposure and risk assessment were conducted for agricultural applicators during preparation of spray suspension and application with speed sprayer and power sprayer on crop fields. Several exposure matrices, including patches, cotton gloves, socks, masks and XAD-2 resin were used to measure the potential exposure for workers. The analytical methods were fully validated to guarantee the precision and accuracy of analysis. As a major factor contributing to the exposure of operators, the amount of active ingredient used per day was identified. Other parameters such as formulation type, density of the canopy were selected as factors for sub-scenarios. Accordingly, 75 percentile of exposure dose was calculated for mixing / loading and application according to scenario, and it was derived as exposure factor of Korean model. In vitro metabolism of kresoxim-methyl was conducted with human liver microsome. Two metabolites were identified. The screening test for identifying which recombinant CYP involved with metabolism of kresoxim-methyl was conducted with 10 human cDNA-expressed CYP isoforms. Eight rCYPs (except 2A6, 2E1) contributed to metabolism of kresoxim-methyl.