Residue behavior, transfer and risk assessment of tolfenpyrad, dinotefuran and its metabolites during tea growing and tea brewing

Tolfenpyrad and dinotefuran are two representative pesticides used for pest control in tea gardens. Their application may bring about a potential risk to the health of consumers. Therefore, it is essential to investigate the residue behavior, transfer and risk assessment of tolfenpyrad, dinotefuran and metabolites from tea garden to teacup.An effective analytical method was established and validated to simultaneously determine tolfenpyrad, dinotefuran and its metabolites (DN and UF) in tea. The average recoveries of tolfenpyrad, dinotefuran, DN and UF were in the range 72.1-106.3%, with relative standard deviations lower than 11.8%. On the basis of the proposed method, the dissipation of tolfenpyrad and dinotefuran in fresh tea leaves followed first-order kinetics models with half-lives of 4.30-7.33 days and 4.65-5.50 days, respectively. With application amounts of 112.5-168.75 g a.i. ha-1 once or twice, the terminal residues of tolfenpyrad and total dinotefuran in green tea were lower than 19.6 and 7.13 mg kg-1 , respectively, and below their corresponding maximum residue limits . The leaching rates of tolfenpyrad and total dinotefuran during the tea brewing were in the ranges 1.4-2.3% and 93.7-98.1%, respectively.Tolfenpyrad and dinotefuran in tea were easily degraded. The RQc and RQa values for tolfenpyrad were 37.6% and 5.4%, which were much higher than for dinotefuran at 24.7% and 0.84%, respectively. The data indicated that there was no significant health risk in tea for consumers at the recommended dosages. The results provide scientific data regarding the reasonable use of tolfenpyrad and dinotefuran aiming to ensure safe tea consuption. © 2021 Society of Chemical Industry.