Dissipation, residues, and dietary risk assessment of difenoconazole in field-planted spinach, wax gourd, and summer squash in China

In the present study, a solid phase extraction coupled with gas chromatography-mass spectrometry to detect difenoconazole residues in spinach, wax gourd, and summer squash was developed. In addition, field trials were conducted to investigate the dissipation and residue behavior of difenoconazole in six representative regions across China for each studied vegetable, and the dietary risk for Chinese consumers was evaluated using risk quotient methods. The average recoveries of difenoconazole in the three matrices were 81.5-97.8%, and relative standard deviations were 4.0-10.2%. Difenoconazole rapidly dissipated in spinach, wax gourd, and summer squash with half-lives of 2.3-5.9 days. The terminal residues of difenoconazole ranged from 0.029 to 4.74 mg/kg in spinach at 3, 5, and 7 days, < 0.01 to 0.036 mg/kg in wax gourd at 5, 7, and 14 days, and < 0.01 to 0.12 mg/kg in summer squash at 5, 7, and 10 days, which were all much lower than the maximum residue limits in China. The dietary risk assessment revealed that the potential risks of difenoconazole for Chinese consumers were acceptable. The risks for children were significantly higher. Therefore, the proposed preharvest intervals for managing difenoconazole in spinach, wax gourd, and summer squash were 3, 5, and 5 days, respectively.