Neonicotinoid residues in commercial Japanese tea leaves produced by organic and conventional farming methods

Collins Nimako; Anri Hirai; Takahiro Ichise; Osei Akoto; Shouta M M Nakayama; Kumiko Taira; Kazutoshi Fujioka; Mayumi Ishizuka; Yoshinori Ikenaka

doi:10.1016/j.toxrep.2021.09.002

Neonicotinoid residues in commercial Japanese tea leaves produced by organic and conventional farming methods

Toxicol Rep. 2021 Sep 15:8:1657-1664. doi: 10.1016/j.toxrep.2021.09.002. eCollection 2021.

Authors

Affiliations

¹ Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Hokkaido, Japan.
² Chemistry Department, Kwame Nkrumah University of Science and Technology, Ghana.
³ Department of Anesthesiology, Tokyo Women's Medical University Center East, Tokyo, Japan.
⁴ Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, United States.
⁵ Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa.
⁶ One Health Research Center, Hokkaido University, Hokkaido, Japan.
⁷ Translational Research Unit, Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Hokkaido University, Hokkaido, Japan.

Abstract

The current study sought to assess the residual levels of neonicotinoid insecticides (NEO) in organic and conventional green tea leaves produced in Japan. A total of 103 tea leaves (thus, 42 organic and 61 conventional), were sampled from grocery stores in Japan. Concentrations of NEOs in the tea leaves were quantified using LC-MS/MS; and the data was used to estimate maximum daily intakes of NEOs within the Japanese population. Seven native NEO compounds and one NEO metabolite were detected in both organic and conventional tea leaves. Detection frequencies (%Dfs) of NEOs in the tea samples (n = 103) were found in the decreasing order; thiacloprid (84.47 %) > dinotefuran (74.76 %) > imidacloprid (69.90 %) ≈ clothianidin (69.90 %) > dm-acetamiprid (63.11 %) > thiamethoxam (58.25 %) > acetamiprid (4.85 %) > nitenpyram (1.94 %). About 94.20 % of the tea leaves contained two or more NEO compounds simultaneously. The %Dfs of NEOs were relatively lower in organic tea leaves, compared to the conventional tea leaves. Various percentile concentrations of NEOs were far lower in organic tea leaves, compared to the conventional tea leaves. The maximum daily intakes of NEOs through consumption of tea (MDIgt) were also lower for organic tea leaves, compared to the conventional tea samples.

Keywords: ADI, acceptable daily intake; Conventional tea leaves; Df, detection frequency; JAS, Japanese Agricultural Standards; LC-ESI/MS/MS, Liquid chromatography-mass spectrometry/mass spectrometry; LOD, limit of detection; LOQs, Limits of quantitation; MAFF, Ministry of Agriculture, Forestry and Fisheries of Japan; MDIgt, maximum daily intakes of NEOs via consumption of green tea leaves; MRLs, minimum residual levels; MRM, multiple-reaction monitoring; NEO, neonicotinoid insecticide; Neonicotinoid insecticide; Organic tea leaves; t1⁄2, half-life.