Dissipation Behavior and Risk Assessment of Three Pesticide Residues Under Combined Application in Greenhouse-Grown Cabbage

Field residue trials were conducted in greenhouse-grown cabbage at both recommended and double dosages to evaluate the degradation dynamics and dietary risks of three pesticides (azoxystrobin, thiamethoxam, and carbendazim). In this study, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method combined with liquid chromatography tandem mass spectrometry was developed to measure the residues of three pesticides in cabbage. The mean recoveries of three pesticides in cabbage were 82.5–104.2%, with relative standard deviations of 2.1–5.2%, meeting the requirements of residual analysis. Based on first-order kinetics, the half-lives of the three pesticides in cabbage were 11.55–33.00 d under field conditions. The health risks associated with three pesticides in cabbage were evaluated using the risk quotient (RQ) method and the EFSA PRIMo 3.1 model. In the final residue experiment, the dietary exposure risks of azoxystrobin and thiamethoxam were all acceptable for children and adults regardless of the dosage or pre-harvest intervals, with the risk quotient (RQ) ranging from 0.040 to 0.363 and 0.022 to 0.417, respectively. However, carbendazim intake posed unacceptable health risks for consumers, with RQ significantly exceeding 1. The EFSA PRIMo 3.1 model also indicated high %ADI values for carbendazim, consistent with the RQ results. Given the significant residual risk associated with carbendazim in cabbage, limiting its use on this crop is recommended.