Fate of Clothianidin and Phoxim in Fresh Corn and Corn Grain: Storage Stability and Human Health Risk Assessment

Corn is a critically important agricultural crop, with different parts consumed at specific growth stages—notably, fresh corn and corn grain. The field residue behaviors of clothianidin and phoxim in fresh corn and corn grain were investigated by using a QuEChERS technique combined with UPLC-MS/MS, and the dietary exposure risks of the insecticides were evaluated. Field trials were conducted under the recommended application conditions (2250 g active ingredient per hectare of 2% clothianidin and phoxim granules, applied once) at 12 agricultural regions across China under various climatic conditions to study the residue levels of pesticides. The samples were collected at harvest of fresh corn and corn grain, separately. The results indicated that the residues of the phoxim remained stable in all samples stored at −20 °C for 6 months (180 days). At harvest, the concentrations of clothianidin in fresh corn ranged from