Residue Dissipation Dynamics and Dietary Risk Assessment of Kasugamycin, Oxine-Copper, Dimethomorph, and Pyraclostrobin in Cucumber

In recent years, pesticides have been overapplied to prevent and control cucumber diseases, and high pesticide residues on cucumbers have become a growing concern. Therefore, the establishment of a rapid and reliable method for the detection of pesticide residues is particularly required to ensure the health of humans and livestock. This study optimized the determination method of pesticide residues in cucumber using a QuEchERS pretreatment combined with an ultrahigh performance liquid chromatography-tandem mass spectrometry. The optimized method achieved a spike recovery rate of 79.1–103.3% for the kasugamycin, oxine-copper, dimethomorph, and pyraclostrobin in cucumber, and the limit of quantification was 0.01 mg/kg. The optimized method was used to detect there residues in 12 regions. The dissipation half-lives of oxine-copper, dimethomorph, and pyraclostrobin were 1.64–2.19, 1.15, and 1.20–1.27 days, respectively. The final residue levels of these pesticides were all below the maximum residue limit. The dietary risk assessment showed that the daily intake of kasugamycin, oxine-copper, dimethomorph, and pyraclostrobin accounted for 0.7, 35.7, 23.7, and 20.5% of the daily allowable intake, respectively, which were all within acceptable ranges. This indicates that under the ecological conditions in China, these pesticides are safe under good agricultural practices. This study provides guidance for the comprehensive evaluation and scientific use of fungicide residues in the cultivation of vegetables cash crops such as cucumber.