Neonicotinoid Residues in Tea Products from China: Contamination Patterns and Implications for Human Exposure

Abstract

Neonicotinoids (NEOs) are a class of systemic insecticides widely used in agriculture owing to their high efficacy and selectivity. As one of the most globally consumed beverages, tea may represent a potential dietary source of pesticide residues. However, limited research has examined NEO contamination in tea and its implications for human exposure, highlighting the need for further investigation. Therefore, this study comprehensively evaluated the residue characteristics, processing effects, and human exposure risks of six NEOs-dinotefuran (DIN), imidacloprid (IMI), acetamiprid (ACE), thiamethoxam (THM), clothianidin (CLO), and thiacloprid (THI)-in Chinese tea products. According to the findings, the primary pollutants, ACE, DIN, and IMI, accounted for 95.65% of the total NEO residues in 137 tea samples, including green, oolong, white, black, dark, and herbal teas. The highest total target NEO (∑₆NEOs) residue level was detected in oolong tea (mean: 57.86 ng/g). Meanwhile, IMI exhibited the highest residue level (78.88 ng/g) in herbal tea due to the absence of high-temperature fixation procedures. Concentrations of DIN in 61 samples (44.5%) exceeded the European Union's maximum residue limit of 10 ng/g. Health risk assessment indicated that both the chronic hazard quotient (cHQ) and acute hazard quotient (aHQ) for adults and children were below the safety threshold (<1). However, children required special attention, as their exposure risk was 1.28 times higher than that of adults. The distribution of NEO residues was significantly influenced by tea processing techniques, such as full fermentation in black tea. Optimizing processing methods (e.g., using infrared enzyme deactivation) and implementing targeted pesticide application strategies may help mitigate risk. These results provide a scientific foundation for enhancing tea safety regulations and protecting consumer health.

Keywords: health risk; human exposure; neonicotinoids; residue characteristics; tea; tea processing.

Figure 1

(A) Comparison of the measured levels of six NEOs and ∑₆NEOs across tea samples. (B) Spearman’s correlation coefficients for different NEO compounds in all tea samples are shown; boxplot ranges from minimum to maximum values; three horizontal lines represent the 25th, 50th, and 75th percentiles; “*” indicates significance at p < 0.05, “**” at p < 0.01, and “***” at p < 0.001; NEOs: neonicotinoids; DIN: dinotefuran; THM: thiamethoxam; CLO: clothianidin; IMI: imidacloprid; ACE: acetamiprid; THI: thiacloprid; ∑₆NEOs: sum concentration of all target NEOs.

Figure 2

Average concentrations (ng/g) of different NEOs across various tea types; DIN, IMI, and ACE represent dinotefuran, imidacloprid, and acetamiprid, respectively; NEOs refer to neonicotinoids; ∑₆NEOs represents the sum concentration of all target NEOs.