Occurrence, fate, and probabilistic risk assessment of fipronil residues in Chinese tea

The objective of this study was to determine the occurrence of fipronil and its three metabolites in tea samples collected from 2011 to 2018 in China, where the use of fipronil in agriculture had been banned since 2009. Among the 726 tea samples, the total fipronils (EFIPs, non-detected (ND)- 140 mu g/kg) were dominated by the parent compound fipronil (ND-80.6 mu g/kg) and its major metabolites fipronil desulfinyl (ND-36.9 mu g/kg) and fipronil sulfone (ND-24.2 mu g/kg), while fipronil sulfide (ND-6.78 mu g/kg) contributed little to the total. A total of 20.0 % and 30.7 % of the tea samples detected EFIPs residues exceeded the maximum residue limits of 0.005 and 0.002 mg/kg set by the European Union and Japan, respectively. The average concentration of EFIPs decreased by 22 times during the three survey periods. By the probabilistic model, the chronic exposure risk of Chinese tea consumers was less than 25 % of the acceptable daily intake of fipronil, and a ten-fold decrease was observed within eight years. The EFIPs residues in tea were within a low health risk for Chinese tea consumers. This was the first study to provide the basic information on the occurrence and the temporal variation of fipronil in tea samples from China.