Occurrence, temporal variation, quality and safety assessment of pesticide residues on citrus fruits in China

Citrus is highly consumed in China and considered a major source of pesticide carrier in human diet. In this paper, pesticide residues in mandarins, tangerines and oranges from China were evaluated, as well as the quality and long-term dietary risks for the Chinese consumers. Temporal variations for eight MRL non-compliant pesticides were also investigated. 106 pesticides were analyzed using QuEChERS procedure and UPLC-MS/MS, GC-MS and GC methods. Forty different pesticides were detected in 86% of the 2922 samples from 2013 to 2018. Chlorpyrifos was the most frequently detected pesticide with a detection rate of 40%. Residues of eight pesticides in 3.8% of the total samples exceeded their MRLs. The most severely excessive pesticide was bifenthrin with 283% MRL. The occurrences and exceeding rates of eight pesticides presented clear temporal variations during the six harvesting years. Isocarbophos, carbofuran and triazophos were the main risk factors threatening the citrus safety pre-2015, whereas profenofos and bifenthrin gradually became dominant after 2016, coinciding with government control measures. The index of quality for residues (IqR) levels of 88% of the samples were below 1.0, which indicated a satisfactory quality of citrus fruits in China, although 70% of the samples contained two or more residues. The cumulative chronic dietary risks were acceptable for both the Chinese general population and children and would not pose health risks. However, more strictly enforced control measures for methidathion and isocarbophos, and reduced usage of triazophos, quinalphos, profenofos and bifenthrin should be pursued to further improve the safety of citrus fruits.