Dissipation behavior, residue distribution and dietary risk assessment of cyromazine, acetamiprid and their mixture in cowpea and cowpea field soil

BACKGROUND Cyromazine and acetamiprid are widely applied as pesticides in agriculture, causing increasing concerns about their residues in crops. In this study, cyromazine, acetamiprid and their mixture were applied to cowpea to investigate their degradation dynamics and perform a dietary risk assessment. RESULTS The dissipation behavior of cyromazine and acetamiprid in the single- and mixed-pesticide groups followed first-order kinetics, with a linear correlation coefficient of 0.910 to 0.987. The half-lives of cyromazine and acetamiprid were 1.56-11.18 days in the four different matrices. The half-life of cyromazine in the mixed-pesticide group was similar to or even shorter than that in the single-pesticide group. The highest levels of cyromazine and acetamiprid in cowpea occurred with a preharvest interval of 7 days and after two or three applications. These levels are below the maximum residue limits recommended by the Chinese Ministry of Agriculture for cyromazine and acetamiprid in cowpea. The risk quotient of cyromazine and acetamiprid ranged from 0.0018 to 0.0418, and the national estimated short-term intake values of the cyromazine and acetamiprid were far below the acute reference dose as recommended by the European Food Safety Authority. CONCLUSION These results suggest that the use of cyromazine and acetamiprid and a cyromazine-acetamiprid mixture in cowpea is safe under the Good Agricultural Practices for Chinese fields, and the use of a cyromazine-acetamiprid mixture affords even better results than the application of cyromazine alone. Moreover, the residue dynamics information will support the label claims for the application of cyromazine, acetamiprid and a cyromazine-acetamiprid mixture to cowpea fruit. (c) 2020 Society of Chemical Industry