Pesticide Residues in Greenhouse Leafy Vegetables in Cold Seasons and Dietary Exposure Assessment for Consumers in Liaoning Province, Northeast China

Excessive pesticide application in greenhouses leads to elevated levels of pesticide residues, especially in cold seasons, thereby posing a potential dietary exposure risk to the residents' health. This study aimed to investigate 65 pesticides in 469 leafy vegetable samples collected from greenhouses in Liaoning province between October 2018 and May 2020. Overall, the pesticide levels in 96.4% (452/469) of the samples were below the MRLs established by the Codex Alimentarius Commission. The detection rate of 65 pesticides ranged from 0.2% to 11.9%. Multiple pesticide contamination was common, with dimethomorph being the most recurrent contaminant. The dietary risk assessment study revealed obvious differences in chronic and acute exposure risk values. The chronic risk quotients (RQcs) for leafy vegetable samples were 0.001%-3.993%, indicating an acceptable public health risk for the residents. As two leafy vegetables highly consumed in cold seasons in northeast China, the acute risk quotients (RQas) of Chinese cabbage samples were significantly lower than 100%; however, pakchoi samples exhibited RQa values ranging from 0.159% to 580.529%, showing an unacceptable acute dietary risk. This highlights that, compared to the chronic dietary risks, the potential acute dietary risks induced by the pesticides are higher in greenhouse-grown leafy vegetables during cold seasons.