Exposure and risk assessment of insecticide methomyl for applicator during treatment on apple orchard

Abstract

Exposure and risk assessments were conducted to evaluate safety of speed spayer (SS) and power sprayer (PS) used for treatment of insecticide methomyl in apple orchard on the operator. Dermal patches, gloves, socks, and masks were used to monitor the potential dermal exposure, and personal air monitor with XAD-2 resins was used to evaluate the potential inhalation exposure. Validation of methods for limit of detection, limit of quantitation, recovery, reproducibility, linearity of calibration, trapping efficiency, and breakthrough tests were performed to obtain reasonable results for quantitative exposure study of methomyl. During application of methomyl, PS resulted in more dermal exposure than SS. Important contaminated parts of body were upper arms, thigh, chest, shin, hand, forearm, and head for both SS and PS. Exposure rate was 44–176 mL/h. Although the level of inhalation exposure was very low during application, relatively higher level was observed for PS than for SS. During mixing/loading, more dermal exposure occurred by SS than that of PS probably due to drift of wettable powder (WP) formulation. Exposure was mostly observed on hand, and 99.9% of hand exposure to soluble liquid formulation (215 mg) in PS was from spill of liquid formulation on gloves. However, the body exposure ratio to total mixing/loading amount and inhalation exposure during mixing/loading was very low. Margin of safety in risk assessment was much larger than 1 in all cases, indicating low risk.