Dynamic Residue Behavior and Risk Assessment of Thiamethoxam With Its Metabolite From Tea Production to Consumption

The entire fate of the widely used insecticide thiamethoxam from field cultivation, manufacturing to brewing were studied. A method to simultaneously detect thiamethoxam and its two metabolites, clothianidin and CGA265307, was developed. The field trial indicated a half-life of thiamethoxam at 3.2 days on tea leaves, meanwhile, generation of clothianidin was observed with the maximum accumulation of 0.0152 mg/kg after 1 day of thiamethoxam application. The processing factors (PFs) during tea manufacturing ranged from 0.16 to 1.36 and 0.72 to 1.27 for thiamethoxam and clothianidin, respectively. Notably, PFs for thiamethoxam and clothianidin were higher during microwave deenzymed green tea manufacturing than pan deenzymed green tea and traditional black tea. Both thiamethoxam and clothianidin showed high infusion factors during tea brewing, whereas the risk quotient indicated an acceptable dietary risk of thiamethoxam with clothianidin through tea consumption. These findings could facilitate a more accurate assessment of safety risks and better protect the health of tea consumers.