Assessment of the exposure of workers to the insecticide imidacloprid during application on various field crops by a hand-held power sprayer

Exposure assessment and risk assessment for imidacloprid were conducted for agricultural workers through mixing/loading and application with a power sprayer in four kinds of crop fields. The spray suspension was prepared with 10% wettable powder (250 g) for 5 min and applied on field crops for 1 h. A patch method and a personal air sampler with XAD-2 resin were used to monitor the dermal and inhalation exposure, respectively. In mixing/loading, the total dermal exposure on the whole body was 0.2 (cucumber) to 2.0 (apple) mg and the most exposed part of body was the hand (48-100% of total exposure). During the application of imidacloprid, whole dermal exposure was in the range of 2.9 (apple) to 9.5 (green pepper) mg. The primary sites exposed to pesticides were legs (51-79% of total exposure) in cucumber, green pepper, and paddy fields, whereas the primary sites were hands (35% of total exposure) in the apple field. The inhalation exposure was determined to be 0.2 (paddy) to 2.8 (cucumber) μg and 0.2 (paddy) to 3.0 (cucumber) μg during mixing/loading and application, respectively. The absorbable quantity of exposure and the margin of safety were determined for risk assessment. Workers were exposed through inhalation as 23-93 and 2-11% of the absorbable quantity of exposure during mixing and application, respectively. The margin of safety of all cases was much higher than 1, indicating the lowest possibility of risk.