Dissipation, Metabolism, Accumulation, Processing and Risk Assessment of Fluopyram and Trifloxystrobin in Cucumbers and Cowpeas from Cultivation to Consumption

Dissipation, accumulation, distribution and risk assessment of fungicides in greenhouse and open-field cowpeas

Pesticide residues in cowpeas have raised worldwide concern. However, only a few studies have focused on pesticide accumulation and distribution in greenhouse and open-field cowpeas. Field trial results suggest that difenoconazole, dimethomorph, thifluzamide and pyraclostrobin dissipated faster in open fields (mean half-lives, 1.72-1.99 days) than in greenhouses (2.09-3.55 days); moreover, fungicide residues in greenhouse cowpeas were 0.84-8.19 times higher than those in the open-field cowpeas. All fungicides accumulated in the greenhouse and open-field cowpeas after repeated spraying. Fungicide residues in old cowpeas were higher than those in tender cowpeas, and residues in the upper halves of cowpea pods were higher than those in the lower halves. In addition, cowpeas distributed in the lower halves of the plants had higher fungicide residues. Our findings suggest that greenhouse cultivation contributed to the pesticide residues in cowpeas after repeated spraying, although the levels of dietary health risks remained acceptable under both cultivation scenarios.

Greenhouse cultivation enhances pesticide bioaccumulation in cowpeas following repeated spraying

Understanding pesticide residue patterns in crops is important for ensuring human health. However, data on residue accumulation and distribution in cowpeas grown in the greenhouse and open field are lacking. Our results suggest that acetamiprid, chlorantraniliprole, cyromazine, and thiamethoxam residues in greenhouse cowpeas were 1.03-15.32 times higher than those in open field cowpeas. Moreover, repeated spraying contributed to the accumulation of pesticide residues in cowpeas. Clothianidin, a thiamethoxam metabolite, was detected at 1.04-86.00 μg/kg in cowpeas. Pesticide residues in old cowpeas were higher than those in tender cowpeas, and the lower half of the plants had higher pesticide residues than did the upper half. Moreover, pesticide residues differed between the upper and lower halves of the same cowpea pod. Chronic and acute dietary risk assessments indicated that the human health risk was within acceptable levels of cowpea consumption. Given their high residue levels and potential accumulation, pesticides in cowpeas should be continuously assessed.