Dissipation and dietary risk assessment of cyflumetofen, bifenazate and their metabolites in citrus in China

Abstract

Pesticides are routinely used to control pests. For many pesticides, however, information is unavailable concerning dissipation and dietary risk, posing a potential threat to human health. To overcome this shortcoming, we evaluated the dissipation and dietary risk of cyflumetofen and bifenazate as well as their metabolites 2-trifluoromethylbenzoic acid and bifenazate-diazene. A method to detect four components was developed by using ultra-high-performance liquid chromatography, whose precision and linearity were satisfactory. The limit of quantification for these compounds was 0.02 mg/kg, and recovery ranged for four spiked levels from 80% to 100%, with relative standard deviation values between 1.6% and 5.3%. Field trials were carried out in China, and levels of four substances were measured at several time points. A half-life (34.04 days) could be established for bifenazate in whole citrus. The terminal residues in citrus pulp were less than it in whole citrus. Moreover, the dietary risk assessment revealed an acceptable risk of two pesticides, whose risk quotients were 10.65% and 43.86% respectively suggesting 30 days as their preharvest intervals. This work provides a comprehensive evaluation of cyflumetofen, bifenazate and their metabolites in citrus, which can serve as a basis for the rational application of these pesticides in crop fields.