Residue levels and risk assessment of pesticides in litchi and longan of China

A total of 57 pesticide residues were analyzed in 155 litchis and 153 longan samples collected from the three main producing provinces of China. They were studied by the QuEChERS extraction method based on analysis using ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS) and gas chromatography (GC) techniques. Health risks from litchis and longans for humans were evaluated by hazard quotient (HQ) and hazard index (HI). Sixteen different pesticides were detected in litchi samples. In longan samples, 19 different pesticides were detected. A total of 72% litchi samples and 52% longan samples contained at least one pesticide residue. Carbendazim, chlorbenzuron and diflubenzuron were found in 25.2%, 28.4%, and 34.8% of the litchi samples, respectively, and 21.6%, 11.8%, and 21.6% of the longan samples, respectively. The banned pesticides carbofuran and omethoate were detected in two litchi samples and one longan sample, respectively. Residue concentrations did not exceed the maximum residue levels (MRLs) in all litchi and longan samples except for carbofuran. Dietary risk assessment results showed that the chronic and acute dietary risks (HQ(c) and HQ(a)) of individual pesticides and the cumulative chronic dietary risks (HIc) of all pesticide residues for adults and children were all less than 100%. However, the cumulative acute dietary risk (HIa) of all pesticide residues from litchi samples for children was 99.85%, which was close to the unacceptable level and should be given more attention. The contributions of insecticide to HIc and HIa were 89.3% and 87.3% in litchi samples and 91.7% and 55.0% in longan samples.