Transfer of pesticide residue during tea brewing: Understanding the effects of pesticide's physico-chemical parameters on its transfer behavior

Pesticide application behavior in green tea cultivation and risk assessment of tea products: a case study of Rizhao green tea

Previous research on pesticides in green tea mainly focused on detection technology but lacked insights into pesticide use during cultivation. To address this gap, a survey was conducted among Rizhao green tea farmers. The survey results showed that most tea farmers were approximately 60 years old and managed small, scattered tea gardens (< 0.067 ha). Notably, tea farmers who had received agricultural training executed more standardized pesticide application practices. Matrine and thiazinone are the most used pesticides. A total of 16 types of pesticides were detected in the tested green tea samples, with 65% of the samples containing residues of at least one pesticide. Notably, higher levels of residues were observed for bifenthrin, cyfluthrin, and acetamiprid. The presence of pesticide residues varied significantly between seasons and regions. The risk assessment results indicated that the hazard quotient (HQ) values for all 16 pesticides detected in green tea were < 1, suggesting that these residue levels do not pose a significant public health concern.

Yolk-shell MOF-on-MOF hybrid solid-phase microextraction coatings for efficient enrichment and detection of pesticides: Structural regulation cause performance differences

Metal-organic frameworks (MOFs) based composites with different structure-activity relationships have been widely used in the field of organic pollutant adsorption and extraction. Here, two MOF-on-MOF composites with different structures (yolk-shell and core-shell) from homologous sources were prepared by a simple in-situ growth synthesis method and structural regulation. In order to verify the effect of composite structure on the extraction capacity, the adsorption performance of the yolk-shell structure (YS-NH2-UiO-66@CoZn-ZIF) and the core-shell structured (NH2-UiO-66@CoZn-ZIF) material were compared by using them as coating material of direct immersion solid-phase microextraction (DI-SPME) to enrich six pesticides in five matrices. The results showed that because of the unique hollow hierarchical structure, high specific surface area (930.68 m2 g-1), abundant and open active sites, and synergistic and complementary adsorption forces, YS-NH2-UiO-66@CoZn-ZIF composites had the maximum adsorption amount of 36.01-66.31 mg g-1 under the same experiment condition, which was 6.81%-34.26 % higher than that of NH2-UiO-66@CoZn-ZIF. In addition, the adsorption mechanism of the prepared materials was verified and elaborated through theoretical simulations and material characterization. Under the optimized conditions, the YS-NH2-UiO-66@CoZn-ZIF-coated SPME-HPLC-UV method had a wide linear range (0.241-500 μg L-1), a good linear correlation coefficient (R2 > 0.9988), a low detection limits (0.072-0.567 μg L-1, S/N = 3) and low quantification limits (0.241-1.891 μg L-1, S/N = 10). The relative standard deviations of individual fibers and different batches of fibers were 0.47-6.20 % and 0.22-2.48 %, respectively, and individual fibers could be recycled more than 104 times. This work provided a good synthetic route and comparative ideas for exploring the in-situ growth synthesis of yolk-shell composites with reasonable structure-activity relationships.

Emerging technologies for the removal of pesticides from contaminated soils and their reuse in agriculture

Pesticides are becoming more prevalent in agriculture to protect crops and increase crop yields. However, nearly all pesticides used for this purpose reach non-target crops and remain as residues for extended periods. Contamination of soil by widespread pesticide use, as well as its toxicity to humans and other living organisms, is a global concern. This has prompted us to find solutions and develop alternative remediation technologies for sustainable management. This article reviews recent technological developments for remediating pesticides from contaminated soil, focusing on the following major points: (1) The application of various pesticide types and their properties, the sources of pesticides related to soil pollution, their transport and distribution, their fate, the impact on soil and human health, and the extrinsic and intrinsic factors that affect the remediation process are the main points of focus. (2) Sustainable pesticide degradation mechanisms and various emerging nano- and bioelectrochemical soil remediation technologies. (3) The feasible and long-term sustainable research and development approaches that are required for on-site pesticide removal from soils, as well as prospects for applying them directly in agricultural fields. In this critical analysis, we found that bioremediation technology has the potential for up to 90% pesticide removal from the soil. The complete removal of pesticides through a single biological treatment approach is still a challenging task; however, the combination of electrochemical oxidation and bioelectrochemical system approaches can achieve the complete removal of pesticides from soil. Further research is required to remove pesticides directly from soils in agricultural fields on a large-scale.

On-site rapid detection of multiple pesticide residues in tea leaves by lateral flow immunoassay

The application of pesticides (mostly insecticides and fungicides) during the tea-planting process will undoubtedly increase the dietary risk associated with drinking tea. Thus, it is necessary to ascertain whether pesticide residues in tea products exceed the maximum residue limits. However, the complex matrices present in tea samples comprise a major challenge in the analytical detection of pesticide residues. In this study, nine types of lateral flow immunochromatographic strips (LFICSs) were developed to detect the pesticides of interest (fenpropathrin, chlorpyrifos, imidacloprid, thiamethoxam, acetamiprid, carbendazim, chlorothalonil, pyraclostrobin, and iprodione). To reduce the interference of tea substrates on the assay sensitivity, the pretreatment conditions for tea samples, including the extraction solvent, extraction time, and purification agent, were optimized for the simultaneous detection of these pesticides. The entire testing procedure (including pretreatment and detection) could be completed within 30 min. The detected results of authentic tea samples were confirmed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), which suggest that the LFICS coupled with sample rapid pretreatment can be used for on-site rapid screening of the target pesticide in tea products prior to their market release.

Neonicotinoids in tea leaves and infusions from China: Implications for human exposure

The ingestion of contaminated tea involves the risk of human exposure to residues of neonicotinoids (NEOs). Nevertheless, there is little empirical research about this topic; to bridge the current knowledge gap, we collected 220 samples of various tea products from four geographical areas in China, including unfermented green tea, semi-fermented white tea and oolong tea, completely fermented black tea, and post-fermented dark tea. A total of six NEOs were detected from the tea leaves and infusions, namely, dinotefuran (DIN), thiamethoxam (THM), clothianidin (CLO), imidacloprid (IMI), acetamiprid (ACE), and thiacloprid (THI). The detection frequencies (DFs) and concentrations of all target NEOs were relatively high across the investigated tea samples, and the DIN, IMI and ACE residues measured in some samples exceeded the maximum residue level (MRL) standards for the European Union. Samples representing the Jiangnan area exhibited greater levels of total target NEOs (∑6NEOs) than samples representing the Jiangbei area (p < 0.001). Moreover, dark tea samples were found to have far higher levels of NEO residues than green (p < 0.001), white (p < 0.05), or oolong (p < 0.001) samples. The health risks associated with exposure to NEO residues via tea were small for both children and adults in terms of acute, chronic, and cumulative dietary exposure risk assessments. The transfer rates (TRs) of NEOs observed in white, black, and dark tea infusions gradually decreased after the third brewing time. As such, it is recommended to only consume tea that has been brewed at least three times. The presented results not only describe the extent of NEO contamination in Chinese tea leaves and infusions, but also provide tea drinking guidelines for consumers.

Modelling the pesticide transfer during tea and herbal tea infusions by the identification of critical infusion parameters

Pesticide residues in tea and herbal tea often exceed EU maximum residue limits. Consideration of the transfer of pesticides from the leaves (called transfer factors) to the brew is essential to assess the associated risk. This study identified infusion parameters influencing the transfer behaviour of 61 pesticides and elaborated a predictive model for pesticides with unknown transfer factors in black, green, herbal and flavoured teas. Tea type and the presence of flavours were the criteria that most influenced the pesticide transfer. Interestingly, infusion parameters that are individual and area dependent such as infusion time, temperature and water hardness, did not play a significant role. Beta regression models developed to characterise pesticide behaviour during infusion showed good predictions for most pesticides and revealed that log (P) was the main physico-chemical parameter to estimate the pesticide transfer. The transfer factors database and validated models are valuable tools for improving risk assessment.

Uptake and translocation of organic pollutants in Camellia sinensis (L.): a review

Camellia sinensis (L.) is a perennial evergreen woody plant with the potential for environmental pollution due to its unique growth environment and extended growth cycle. Pollution sources and pathways for tea plants encompass various factors, including atmospheric deposition, agricultural inputs of chemical fertilizers and pesticide, uptake from soil, and sewage irrigation. During the cultivation phase, Camellia sinensis (L.) can absorb organic pollutants through its roots and leaves. This review provides an overview of the uptake and translocation mechanisms involving the absorption of polycyclic aromatic hydrocarbons (PAHs), pesticides, anthraquinone (AQ), perchlorate, and other organic pollutants by tea plant roots. Additionally, we summarize how fresh tea leaves can be impacted by spraying pesticide and atmospheric sedimentation. In conclusion, this review highlights current research progress in understanding the pollution risks associated with Camellia sinensis (L.) and its products, emphasizing the need for further investigation and providing insights into potential future directions for research in this field.

Simultaneous Screening and Quantification of 479 Pesticides in Green Tea by LC-QTOF-MS

A high-throughput screening and quantification method for 479 pesticides in green tea was established based on solid-phase extraction combined with liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Pesticides were extracted from samples using an optimized SPE (TPT cartridges) procedure. LC-QTOF-MS in All Ions MS/MS scan mode acquired full MS data for quantification and product ion spectra for identification. LC-QTOF-MS quantification was achieved using matrix-matched standard calibration curves to achieve the optimal method accuracy. The method performance characteristics included the linearity, overall recovery, precision, and measurement uncertainty being evaluated. The validation results exhibited a good sensitivity with the LOQs of 5-55 µg/kg, which was satisfactory for their MRLs in China or the EU. The recoveries of more than 92.7% of the 479 pesticides in green tea were 70-120% at the three spiked levels with a precision of ≤20%. Finally, this method was employed to analyze 479 pesticides in 95 tea samples from markets in China. The test results of the tea samples showed that tolfenpyrad, buprofezin, and pyridaben were found with lower concentrations. The method has effectively improved the determination efficiency of pesticide residue screening by high-resolution mass spectrometry in green tea.

Effects of an organic diet intervention on the levels of organophosphorus metabolites in an adult cohort

Pesticides are a group of organic compounds used to control weeds or insect infestations in agriculture. Diet is the major route of human exposure to these compounds, which can cause serious health problems, even when the intake occurs at low concentrations. Hence, the consumption of organic food is an appropriate strategy to minimize the exposure to pesticides. A prospective, randomized study was conducted to assess the impact of an organic dietary intervention on the levels of urinary dialkyl phosphates (DAP). A screening of 204 pesticides was also carried out in order to confirm the absence of these compounds in organic food. The analytical results showed that only 20 of the 204 pesticides (9.8 %) had concentrations above the limit of quantification in one or more samples of the organic food consumed by the participants. It is substantially lower than the levels of pesticides found in other studies analysing conventional food, confirming the diet as suitable for the organic dietary intervention. A general reduction of most DAP metabolites in urine was found, being significant (p < 0.05) the decrease of dimethyl phosphate (DMP) (0.49 µg/g creatinine in Day 1 vs. 0.062 µg/g creatinine in Day 6), dimethyl thiophosphate (DMTP) (0.49 µg/g creatinine in Day 1 vs. 0.093 µg/g creatinine in Day 6) and diethyl phosphate (DEP) (0.28 µg/g creatinine in Day 1 vs. 0.12 µg/g creatinine in Day 6). In addition, the molar score for the total dimethyl DAP (ΣMP) and total dialkyl phosphate (ΣDAP) also showed significant differences after changing a conventional diet by an organic diet, being reduced from 0.008 µmol/g to 0.002 µmol/g for ΣMP and from 0.012 µmol/g to 0.003 µmol/g for ΣDAP. To the best of our knowledge, this is the first study that evaluates both the impact of an organic diet in the exposure to DAP and the levels of 204 pesticides in the organic food provided to the participants. In summary, the consumption of organic products decreases the dietary intake of pesticides, thus reducing also the potential adverse effects on human health.

The bitter side of teas: Pesticide residues and their impact on human health

Tea (Camellia sinensis) is one of the most widely consumed non-alcoholic beverages globally, known for its rich composition of bioactive compounds that offer various health benefits to humans. However, the cultivation of tea plants often faces challenges due to their high vulnerability to pests and diseases, resulting in the heavy use of pesticides. Consequently, pesticide residues can be transferred to tea leaves, compromising their quality and safety and potentially posing risks to human health, including hormonal and reproductive disorders and cancer development. In light of these concerns, this review aims to: (I) present the maximum limits of pesticide residues established by different international regulatory agencies; (II) explore the characteristics of pesticides commonly employed in tea cultivation, encompassing aspects such as digestion, bioaccessibility, and the behavior of pesticide transfer; and (III) discuss the effectiveness of detection and removal methods for pesticides, the impacts of pesticides on both tea plants and human health and investigate emerging alternatives to replace these substances. By addressing these critical aspects, this review provides valuable insights into the management of pesticide residues in tea production, with the goal of ensuring the production of safe, high-quality tea while minimizing adverse effects on human health.

Phenolic-based non-ionic deep eutectic solvent for rapid determination of water soluble neonicotinoid insecticides in tea infusion

Challenges were raised to established analytical method for monitoring water soluble neonicotinoid insecticide (NEOs) residues in tea infusion. Phenolic-based non-ionic deep eutectic solvent (NIDES) composed by a mixture of DL-menthol and thymol (molar ratio of 1:3) was applied to achieve the determination of selected NEOs. Factors influenced extraction efficiency have been evaluated and molecular dynamics approach was conducted aming to provide a new insight to explain its extraction mechanism. It is found that Boltzmann averaged solvation energy of NEOs was negatively correlated with extraction efficiency. The method validation results indicated good linearities (R² ≥ 0.99), sensitive LOQs (0.05 μg L^-1), high precisions (RSD < 11%) and satisfactory recoveries (57.7%∼98%) at 0.05 μg L^-1 ∼ 100 μg L^-1. The intake risk of NEOs in tea infusion samples were acceptable which residues in range of 0.1 μg L^-1 ∼ 3.5 μg L^-1 for thiamethoxam imidacloprid and thiacloprid. This method showed advantages of rapid, green, and easy operation.

Detection methods, migration patterns, and health effects of pesticide residues in tea

Due to its rich health benefits and unique cultural charm, tea drinking is increasingly popular with the public in modern society. The safety of tea is the top priority that affects the development of tea industry and the health of consumers. During the process of tea growth, pesticides are used to prevent the invasion of pests and diseases with maintaining high quality and stable yield. Because hot water brewing is the traditional way of tea consumption, water is the main carrier for pesticide residues in tea into human body accompanied by potential risks. In this review, pesticides used in tea gardens are divided into two categories according to their solubility, among which water-soluble pesticides pose a greater risk. We summarized the methods of the sample pretreatment and detection of pesticide residues and expounded the migration patterns and influencing factors of tea throughout the process of growth, processing, storage, and consumption. Moreover, the toxicity and safety of pesticide residues and diseases caused by human intake were analyzed. The risk assessment and traceability of pesticide residues in tea were carried out, and potential eco-friendly improvement strategies were proposed. The review is expected to provide a valuable reference for reducing risks of pesticide residues in tea and ensuring the safety of tea consumption.

The metabolism and dissipation behavior of tolfenpyrad in tea: A comprehensive risk assessment from field to cup

The metabolites of pesticides usually require rational risk assessment. In the present study, the metabolites of tolfenpyrad (TFP) in tea plants were identified using UPLC-QToF/MS analysis, and the transfer of TFP and its metabolites from tea bushes to consumption was studied for a comprehensive risk assessment. Four metabolites, PT-CA, PT-OH, OH-T-CA, and CA-T-CA, were identified, and PT-CA and PT-OH were detected along with dissipation of the parent TFP under field conditions. During processing, 3.11-50.00 % of TFP was further eliminated. Both PT-CA and PT-OH presented a downward trend (7.97-57.89 %) during green tea processing but an upward trend (34.48-124.17 %) during black tea manufacturing. The leaching rate (LR) of PT-CA (63.04-101.03 %) from dry tea to infusion was much higher than that of TFP (3.06-6.14 %). As PT-OH was no longer detected in tea infusions after 1 d of TFP application, TFP and PT-CA were taken into account in the comprehensive risk assessment. The risk quotient (RQ) assessment indicated a negligible health risk, but PT-CA posed a greater potential risk than TFP to tea consumers. Therefore, this study provides guidance for rational TFP application and suggests the sum of TFP and PT-CA residues as the maximum residual limit (MRL) in tea.

Phenylboronic acid-functionalized magnetic metal-organic framework nanoparticles for magnetic solid phase extraction of five benzoylurea insecticides

This research involves the construction of a phenylboronic acid-functionalized magnetic UiO-66 metal-organic framework (MOF) nanoparticle (CPBA@UiO-66@Fe₃O₄). Its design is primarily for the magnetic solid phase extraction (MSPE) of benzoylurea insecticides. An organic ligand, 2-amino terephthalic acid (2-ATPA), facilitated the introduction of amino groups while keeping the original crystal structure of UiO-66 intact. The constructed UiO-66 MOF showcases a porous structure and extensive surface area, thereby providing an optimal platform for further functionalization. The employment of 4-carboxylphenylboronic acid as a modifier notably amplified the extraction efficiency for benzoylureas. This improvement was due to the formation of B-N coordination and other secondary interactions. By integrating this with high-performance liquid chromatography (HPLC), we established a quantitative analytical method for benzoylurea insecticides. This method achieved a wide linear range (2.5-500 μg L^-1 or 5-500 μg L^-1), satisfactory recoveries (83.3-95.1%), and acceptable limits of detection (LODs: 0.3-1.0 μg L^-1). The developed method proved successful when applied to six tea infusion samples, representing China's six major tea categories. Semi-fermented and light-fermented tea samples demonstrated relatively higher spiking recoveries.

A liquid chromatography-time-of-flight/mass spectrometry method for analysis of pesticides and transfer behavior in Radix Codonopsis and Angelica sinensis decoctions

The safety of traditional Chinese medicine (TCM) has garnered considerable interest worldwide. In this study, a high-throughput method for the determination of 255 pesticide residues in decoctions of Radix Codonopsis and Angelica sinensis was developed using liquid chromatography-time-of-flight/mass spectrometry. The methodological verification demonstrated the accuracy and reliability of this method. The frequently detected pesticides in Radix Codonopsis and Angelica sinensis were determined to build a correlation between pesticide properties and the transfer rate of pesticide residues in their decoctions. Water solubility (WS) with a higher correlation coefficient (R) made a significant contribution to the accuracy of the transfer rate prediction model. The regression equations for Radix Codonopsis and Angelica sinensis were T = 13.64 log WS + 10.56 with a correlation coefficient (R) of 0.8617 and T = 10.66 log WS + 25.48 with a correlation coefficient (R) of 0.8072, respectively. This study provides preliminary data on the potential risk of exposure to pesticide residues in Radix Codonopsis and Angelica sinensis decoctions. Furthermore, as a case study on root TCM, this approach may serve as a model for other TCMs.

Assessing transfer of aluminum during tea brewing and associated population health risks

Tea is consumed widely around the world owing to its refreshing taste and potential health benefits. However, drinking tea is considered a major route for dietary aluminum exposure in areas where tea consumption is relatively large. To assess the health risk associated with drinking tea, the contamination level of aluminum was determined in 81 tea samples. The transfer rate of aluminum during tea brewing was investigated. Then based on the site-specific exposure parameters such as consumption data and body weight for six different subpopulations in Fujian, the exposure risks were estimated using a probabilistic approach. Results demonstrate that the contents of aluminum in green tea, white tea, oolong tea, and black tea were significantly different according to the one-way ANOVA analysis (p < 0.05). The transfer rate of aluminum were 32.6%, 31.6%, 26.3%, and 14% for white tea, black tea, oolong tea, and green tea, respectively. With respect to the oral reference dose, the exposure of inhabitants in Fujian to aluminum through drinking tea is under control (even at the 99th percentile).

Migration behavior and dietary exposure risk assessment of pesticides residues in honeysuckle (Lonicera japonica Thunb.) based on modified QuEChERS method coupled with tandem mass spectrometry

The honeysuckle was widely appreciated as tea beverage owing to the biological activities and the unique aroma and flavor. It is in urgent requirement to explore the migration behavior and dietary exposure as the pesticide residues would bring about potential risks through honeysuckle intake. The optimized QuEChERS procedure coupled with the HPLC-MS/MS and GC-MS/MS methods were employed to determine 93 pesticide residues of seven classifications including carbamates, pyrethroid, triazoles, neonicotinoids, organophosphorus, organochlorine, and others for 93 honeysuckle samples from four primary production bases. As a result, 86.02% of the samples were contaminated by at least one pesticide. Unexpectedly, the banned pesticide of carbofuran was also identified. The migration behavior of metolcarb was the highest, whereas thiabendazole contributed less risk to the infusion with relative lower transfer rate. Both the chronic and acute exposure yielded low risk for human health with five high risk pesticides of dichlorvos, cyhalothrin, carbofuran, ethomyl, and pyridaben. Besides, this study provides foundation of dietary exposure risk assessment for honeysuckle and other likewise products.

Pesticides, trace elements and pharmaceuticals in tea samples available in Belgian retail shops and the risk associated upon acute and chronic exposure

Over the last decade, the consumption of tea and herbal tea has gained more and more popularity across the globe, but the potential presence of chemical contaminants (e.g. pesticides, trace elements, synthetic drugs) may raise health concerns. This study analysed selected teas available in Belgian retail stores and performed a risk assessment for these samples. No chemical adulteration could be detected in dry tea material. More than 38% of the dry leaves samples contained at least one pesticide exceeding the maximal residue level (MRL) set by the EU. However, further risk assessment, based on the values of pesticide residues and the toxic trace elements encountered in the brew, demonstrate that the consumption of these teas will not give rise to health concerns. Nonetheless, attention should be given to the leaching potential of nickel from teas and the presence of arsenic in brews from algae containing teas.

Distribution pattern, removal effect, transfer behavior of ten pesticides and one metabolite during the processing of grapes

Grapes' growth and processing conditions have various effects on pesticides with different physicochemical properties. Therefore, it is important for the healthy human diet to investigate pesticide residue behavior. To explore the relationship between pesticide residue behavior and physicochemical properties, the distribution of ten pesticides and one metabolite on grape peel and pulp was examined and the results showed that pesticides with low octanol-water partition coefficient (Kow) were more likely to be transferred to the pulp as the harvest interval increases. The removal methods were ranked according to pesticide removal effectiveness as follows: peeling > ozone water washing > tap water washing. Furthermore, the logKow played a key role in pesticide transfer rates during the juicing and winemaking. Notably, drying was the process of increasing pesticide residues. Additionally, the prediction models for the PFs of the pesticides in the juicing and winemaking processes were constructed as PFj = 0.952-0.116logKow (r = 0.886) and PFw = 0.736-0.143logKow (r = 0.959) by stepwise regression analysis. The prediction models recommended that Kow could be used to predict pesticide residues in grape juice and wine, which can predict the effect of pesticide physicochemical properties on PFs.

Residue behaviors, processing factors and transfer rates of pesticides and metabolites in rose from cultivation to consumption

The presence of pesticide residues in rose makes it necessary to pay special attention to the proper cultivation to consumption. In this study, the inherent regularity of residue behaviors, processing factors and transfer rates of pesticides and potential metabolites during rose planting, drying and brewing was researched. The half-lives in the bud, corolla and leaf were 0.5-2.9, 0.3-1.7 and 2.6-25.9 d, respectively. Residues were more distributed in leaf, followed by corolla, bud and root. Systemic pesticides could appear in the root 1 day after application, and non-systemic pesticides were not detected in the root. The effect of sun and oven drying (80 °C) was more significant in promoting the degradation of cyazofamid, bifenazate, thiamethoxam and imidacloprid. The processing factors (PFs) of other pesticides were > 1. Our results showed that the transfer rate of residues during brewing was negatively correlated exponentially with Log Kow and positively logarithmically correlated with melting point and water solubility. The transfer rate of residues and antioxidant capacity in infusion were significantly affected by different brewing conditions.

Concentrations, generation and risk characterization of phthalimide in tea-derived from folpet or not?

The fungicide folpet is rapidly degraded into phthalimide (PI) during both thermal processing and analytical procedures in sample preparation; thus, its residue definition has been modified into the sum of itself and PI. Tea is one of the world's most popular nonalcoholic beverages, where folpet is not listed as an applicable pesticide. To demonstrate how serious false-positives and overestimation in dietary risk are caused by the application of a new residue definition, the residue pattern of PI in made tea and processed tea leaves, along with its transfer rate during tea brewing and corresponding dietary risk, were investigated in the present study. The results revealed that PI residue in tea ranged from <10 μg/kg to 180 μg/kg with a median value of 10 μg/kg, 7.3 % of which was over the maximum residue limit established by EU (100 μg/kg, expressed as folpet). The PI residue in green tea was obviously higher than that in black, dark and oolong tea. Simulated heating experiments revealed that PI can arise from improper heating of folpet-free fresh tea leaves, and thus green tea bears a higher risk for its manufacturing employing a comparatively higher temperature. The transfer rate of PI during tea brewing was 104 ± 14 %. Nevertheless, the risk of PI through drinking tea was negligible to humans depending on the risk quotient (RQ) value, which was significantly lower than 1.

Dissipation pattern and conversion of pyrrolizidine alkaloids (PAs) and pyrrolizidine alkaloid N-oxides (PANOs) during tea manufacturing and brewing

Pyrrolizidine alkaloids (PAs) and pyrrolizidine alkaloid N-oxides (PANOs) are toxic secondary metabolites in plants, and one kind of main exogenous pollutants of tea. Herein, the dissipation pattern and conversion behavior of PAs/PANOs were investigated during tea manufacturing and brewing using ultra high-performance liquid chromatography tandem mass spectrometry. Compared with PAs (processing factor (PF) = 0.73-1.15), PANOs had higher degradation rates (PF = 0.21-0.56) during tea manufacturing, and drying played the most important role in PANOs degradation. Moreover, PANOs were firstly discovered to be converted to corresponding PAs especially in the time-consuming (spreading of green tea manufacturing and withering of black tea manufacturing) and high-temperature tea processing (drying). Moreover, higher transfer rates of PANOs (≥75.84%) than that of PAs (≤56.53%) were observed during tea brewing. Due to higher toxicity of PAs than PANOs, these results are conducive to risk assessment and pollution control of PAs/PANOs in tea.

Residue degradation, transfer and risk assessment of pyriproxyfen and its metabolites from tea garden to cup by ultra performance liquid chromatography tandem mass spectrometry

BACKGROUND

Tea is one of the most popular drinks in the world. The growth of tea plant is inseparable from the control of pesticides on diseases and pests. Pyriproxyfen is used as a pesticide substitute to control insect pests in tea gardens, but little is known about its residue degradation. Here, we performed an integrative study of the degradation and metabolism of pyriproxyfen from the tea garden to the cup.

RESULTS

The dissipation half-life of pyriproxyfen during tea growth was 2.74 days, and five metabolites PYPAC, PYPA, DPH-Pyr, 5''-OH-Pyr, and 4'-OH-Pyr were generated. The total processing factors for pyriproxyfen in green tea and black tea were 2.41-2.83 and 2.77-3.70, respectively. The residues of pyriproxyfen and its metabolites were affected by different processing steps. The total leaching rates of pyriproxyfen from green tea and black tea into their infusions were 9.8-12.3% and 5.3-13.8%, respectively. The leaching rates of the five metabolites were higher than that of pyriproxyfen and increased the intake risk.

CONCLUSION

To ensure safe consumption, the recommended maximum residue limit value of pyriproxyfen in tea can be set to 5 mg kg^-1 and the pre-harvest interval can be set to 5 days. © 2022 Society of Chemical Industry.

Dissipative behavior, residual pattern, and risk assessment of four pesticides and their metabolites during tea cultivation, processing and infusion

BACKGROUND

In recent years, metabolic products of pesticides have gained much attention due to their substantial characteristics as organic pollutants. So far, the behavior and metabolite levels of pesticide metabolites in crops have not been characterized well. In the present study, four registered pesticides (imidacloprid, diafenthiuron, malathion and chlorothalonil) were applied on tea plants in Fujian and Sichuan to characterize their metabolites residue pattern and dietary risk.

RESULTS

Four pesticides dissipated first-order kinetics in the fresh tea leaves with the half-lives of 1.4-3.8 days. Nine metabolites were detected in the fresh tea leaves and green tea after processing. The metabolites residues showed an increasing trend first and then declined after treatment, and reached the maximum near the half-lives of pesticide. Compared with the parent pesticide, the total residue and acute risk (included the metabolites) increased by 1.7-105.2 times. Some metabolites, especially those whose parent pesticides have high water solubility and low Log Kow, will be more easily transferred to tea infusion.

CONCLUSION

Pesticides were metabolized rapidly on tea plants after application, but the production of metabolites increased the health risk of tea consumption. These results could provide insights to use the pesticides in tea gardens and risk monitoring after application. © 2022 Society of Chemical Industry.

Residue levels, household processing evolution and risk assessment of chlorothalonil, SDS-3701, metalaxyl and dimethomorph in Dendrobium officinale Kimura et Migo

Dendrobium officinale, a minor crop with medicinal and edible value, is increasingly entering people's diets, but the pesticide residues on it have received little attention. In this work, field trials were conducted under good agricultural practice (GAP) conditions to investigate the residues of chlorothalonil, SDS-3701, metalaxyl and dimethomorph in D. officinale, then the evolution of these pesticides after household processing were studied. The results indicated that chlorothalonil, SDS-3701, metalaxyl and dimethomorph were 2.41-30.12, 0.20-1.23, 0.07-0.80, 0.19-7.90 mg kg^-1 respectively in stems at recommended preharvest interval (PHI, 30 d). Washing and soaking removed the pesticides in fresh stems with the processing factors (PFs) of 0.41-1.14 and 0.12-1.13, respectively. In brewing test, the transfer rates (TRs) of pesticides in dry stems decreased from the first time (4.27-95.40%) to the third time (3.89-15.57%). Intake risk assessments were also conducted and the risk quotients (RQs) were no more than 27.02% for all compounds in different samples, which indicated acceptable risks for consumers. As effective risk-reducing home processing methods, washing, soaking and multiple brewing were suggested in this work, hoping to help consumers with diet safety.

Transfer behavior of pesticides from honeysuckle into tea infusions: Establishment of an empirical model for transfer rate prediction

Affected by some external conditions and internal factors, pesticides can be transferred from tea into its infusion, causing subsequent damage to humans as tea infusion is generally consumed. This study aimed to explore the inherent regularity in transfer behavior of 23 pesticides belonging to different classes from honeysuckle to its tea infusion, and to understand the effects of external brewing conditions and internal physicochemical parameters of the pesticides on their transfer rates. Results indicated that the transfer rates (Rt) of pesticides from honeysuckle into tea solutions increased with prolonged brewing time, or adding a cover on a container, but decreased with increasing the times of infusion. In addition, the transfer potential of these pesticides greatly depended on their physicochemical properties but not their type. The pesticides with high water solubility and low water partition coefficient (LogKow, e.g., omethoate) were more easily transferred into tea infusions than those with low water solubility and high LogKow (e.g., chlorpyrifos). Compared the tea brewing in a covered container, the empirical models obtained in an uncovered cup predicted the transfer behavior and drinking risk of pesticides potentially introduced into honeysuckle and its tea infusion. The linear equation was as follow: Rt = 10.756 LogWS + 7.517, R = 0.8771. In practice, honeysuckle should be brewed in an uncovered cup within a short brewing time, and the first tea infusion should be abandoned to reduce the transfer percentage of pesticides. This study provided beneficial references for pesticide application in honeysuckle plantation to establish realistic maximum residue limits of multi-pesticides in honeysuckle tea and related products.

Nanotechnology-based approaches applied to nutraceuticals

Nutraceuticals and food industries are opening to a tremendously upcoming technology in the field of "Nano science". A new prospect has been defined by nanotechnology by conferring modified properties of nanomaterials and its application in the development of nanoformulations, nutritional supplements and food industry. Nanomaterials reveal exclusive properties because of their small size and high surface/volume ratio; thus, they have a complete application in nutraceuticals and food sector. In the existent review article, we obligate to present a comprehensive outline of the application of nanomaterials in development of advanced nano-based nutraceuticals with enhanced bioavailability, solubility, improved encapsulation efficiency, increased stability, sustained and targeted drug delivery, protection against degradation and microbial contamination and with improved pharmacological activity. It also highlights the importance of nanomaterials as nanosensors/nano-bio sensors for encapsulating peptides, antibodies, enzymes, etc. and in the food packaging industry and its future application. Thus, the review aims to focus on the benefits and new dimensions provided by nanomaterials and nanotechnology in health sectors by improving treatment strategies and quality of life.

Dissipation behavior and risk assessment of tolfenpyrad from tea bushes to consuming

The dissipation behavior of tolfenpyrad, a widely used pyrazole insecticide in tea plantations, was investigated during tea bushes growing, manufacturing and brewing. Tolfenpyrad dissipated fast on the tea bushes with the half-lives of 1.8-2.3 days. Manufacturing processes of green tea and black tea further reduced the tolfenpyrad residue by 3.5%-36.4%. The average processing factors (PFs) of tolfenpyrad ranged from 0.68 to 1.40 and 0.84 to 1.30 during the processing of green tea and black tea, respectively. Then a low infusion factor of 9.8%-19.9% was observed during the brewing of made tea, as the water solubility of tolfenpyrad was only 0.087 mg/L. Therefore, more than 96% of the initial deposition of tolfenpyrad was dissipated and not accessible for consuming. Results of the risk quotient (RQ) assessment also indicated a negligible health risk by tea consumption. Results from this study indicated that the residue of tolfenpyrad can be reduced by proper field management, manufacturing and brewing processes, where field dissipation and brewing were key steps to minimize its risks. Data of this study could also provide guidance for rational application of tolfenpyrad in tea plantations.

Multi-residue analytical method development and risk assessment of 56 pesticides and their metabolites in tea by chromatography tandem mass spectroscopy

A modified QuEChERS method coupled to chromatography tandem mass spectroscopy was established and used to identify 56 pesticides and 21 metabolites residues in tea samples. The average recoveries for the target compounds ranged from 71% to 109% with RSDs of 1-17%. Pesticides and metabolites residues in 248 tea samples from China were investigated by the developed method, and the dietary intake risk for consumers was estimated. The results showed that 36 pesticides and 14 metabolites were detected with concentrations of 0.0050-7.7 mg/kg. There are unlikely to present a public health concern for Chinese consumers. The acute risk of pesticides would be exaggerated when calculated by the residue level in tea instead of tea infusion. The unauthorized and banned pesticide contributed to the chronic and acute hazard index by 68% and 36%, respectively. The cumulative risk of residual pesticides and their metabolites on human health deserve further attention.

Residue behavior, transfer and risk assessment of tolfenpyrad, dinotefuran and its metabolites during tea growing and tea brewing

BACKGROUND

Tolfenpyrad and dinotefuran are two representative pesticides used for pest control in tea gardens. Their application may bring about a potential risk to the health of consumers. Therefore, it is essential to investigate the residue behavior, transfer and risk assessment of tolfenpyrad, dinotefuran and metabolites from tea garden to teacup.

RESULTS

An effective analytical method was established and validated to simultaneously determine tolfenpyrad, dinotefuran and its metabolites (DN and UF) in tea. The average recoveries of tolfenpyrad, dinotefuran, DN and UF were in the range 72.1-106.3%, with relative standard deviations lower than 11.8%. On the basis of the proposed method, the dissipation of tolfenpyrad and dinotefuran in fresh tea leaves followed first-order kinetics models with half-lives of 4.30-7.33 days and 4.65-5.50 days, respectively. With application amounts of 112.5-168.75 g a.i. ha^-1 once or twice, the terminal residues of tolfenpyrad and total dinotefuran in green tea were lower than 19.6 and 7.13 mg kg^-1 , respectively, and below their corresponding maximum residue limits . The leaching rates of tolfenpyrad and total dinotefuran during the tea brewing were in the ranges 1.4-2.3% and 93.7-98.1%, respectively.

CONCLUSION

Tolfenpyrad and dinotefuran in tea were easily degraded. The RQ_c and RQ_a values for tolfenpyrad were 37.6% and 5.4%, which were much higher than for dinotefuran at 24.7% and 0.84%, respectively. The data indicated that there was no significant health risk in tea for consumers at the recommended dosages. The results provide scientific data regarding the reasonable use of tolfenpyrad and dinotefuran aiming to ensure safe tea consuption. © 2021 Society of Chemical Industry.

Dissipation of Chlorpyrifos in Bottled Tea Beverages and the Effects of (-)-Epigallocatechin-3-Gallate

ABSTRACT

Bottled tea beverages (BTB) are popular for the health benefits and convenience. Because chlorpyrifos (CP) is commonly used as a biomarker for exposure, as well as a pesticide in the field, it is important to determine the dynamics of CP dissipation in BTB to better perform risk assessments. This study focused on the dynamic behavior of CP for 22 days by fortifying bottled green tea, dark tea, and oolong tea beverages with the parent chemical and analyzing the degradation products. Photoinduction was used to generate the two transient intermediates: the reactive oxygen species from H2O2 and the triplet excited state of CP from the parent chemical in water were designed to observe the effects of (-)-epigallocatechin-3-gallate (EGCG) on the dissipation and transformation of CP. The results indicated that the CP degraded in BTB and the main products were detected. The half-life values of CP illustrated that EGCG increased the dissipation of CP by combination with CP and inhibited the generation of CP-oxon by scavenging the emerged oxidant, the reactive oxygen species, and interfering with the transformation of the triplet excited state of CP. This work suggests EGCG could play various roles in the dissipation and transformation of CP. Thus, a comprehensive identification of CP degradation should be performed when assessing the exposure risk in drinking BTB.

HIGHLIGHTS

Residue pattern of chlorpyrifos and its metabolite in tea from cultivation to consumption

BACKGROUND

Chlorpyrifos (CPF) is a broad-spectrum organophosphorus pesticide widely used to control tea geometrid (Ectropis oblique) and tea green leafhoppers (Empoasca pirisuga Matsumura) in tea trees. The major metabolite of CPF in water, plants, and animals is 3,5,6-trichloro-2-pyridinol, which is more toxic than CPF. However, the dissipation pattern of CPF in tea is unknown.

RESULTS

An optimized QuEChERS sample preparation method combined with ultra-performance liquid chromatography-tandem mass spectrometry was applied to determine the residues of chlorpyrifos and its metabolite in tea during tea planting and green tea processing. During tea planting, the sum of chlorpyrifos and its metabolite dissipated rapidly with a half-life of 1.93 days for tea shoots. The residues of chlorpyrifos and its metabolite in made green tea were 96.89 and 35.88 μg kg^-1 on the seventh day. The values for processing factors of chlorpyrifos and its metabolite were all less than 1, showing that each green tea manufacturing step was responsible for the reduction. The transfer rates of chlorpyrifos and its metabolite from made green tea to its infusion were 0.68-4.62% and 62.93-71.79%, respectively.

CONCLUSION

The risk of chlorpyrifos was negligible to human health based on the hazard quotient, which was 7.4%. This study provides information relevant to the reasonable application of chlorpyrifos in tea planting and is potentially helpful for tea exporting and importing countries to establish harmonized maximum residue limits. © 2020 Society of Chemical Industry.

Nontarget and high-throughput screening of pesticides and metabolites residues in tea using ultra-high-performance liquid chromatography and quadrupole-orbitrap high-resolution mass spectrometry

A Sin-QuEChERS, coupled to UHPLC Q-Exactive Orbitrap MS, was used for nontargeted high-throughput rapid screening and quantitative analysis of residual pesticides and metabolites in green teas. The sample was extracted with 0.1% formic acid in acetonitrile with shaking, salted out and centrifuged, and purified with Sin-QuEChERS Nano solid phase extraction column; with Full MS/ddMS2 as the data collection mode, the database containing 384 pesticides combined with Trace Finder 3.0 software, In the absence of standard products, rapid screening and confirmation of potential pesticide residues in tea samples with accurate mass, isotope abundance ratio, secondary fragment ions, etc. 20 pesticides were used as quality controls to verify the screening method, and the linearity of these pesticides was between 1 and 200 μg/L, and the correlation coefficients were all greater than 0.9922. Moreover, the LOQ was between 0.002 and 0.01 mg/kg. The average recoveries of spiked tea samples were 74%-111%. Efficiency and reliability of this method were investigated by the analysis of 38 Chinese green tea samples. 18 potential residual pesticides were detected by non-targeted screening. The researchers then conducted a quantitative analysis of the 18 potential residual pesticides.

Occurrence of pesticides in white tea and a corresponding risk exposure assessment for the different residents in Fujian, China

White tea has been of increasing public interest worldwide owing to its health benefits. Based on 2 years of surveillance, the long-term and cumulative chronic exposure risks of pesticide residues through white tea drinking were assessed for different subpopulations in Fujian, China. Twenty-five different pesticides were found, and 74.8% of samples contained at least one pesticide residue. The most frequently detected pesticide was bifenthrin with detection rates of 61.6%. Risk assessment was performed using both the deterministic approach and semiprobabilistic model under the best-case and the worst-case scenarios. The results demonstrated that the dietary risks were extremely low for six different subpopulations in which the risks for adults over the age of 41 were relatively higher. The risk ranking scheme indicated that isocarbophos and triazophos were considered to be of medium risk. The different use suggestions for the 25 positive pesticides are proposed to further minimize the exposure risk to consumer health. PRACTICAL APPLICATION: Tea is the second most popular nonalcoholic beverage throughout the world. Pesticides are used to improve the yield of tea. Pesticide residues in tea could be one of the exposure pathways for consumers. Monitoring residual levels and assessing the health risk assessment in tea are thus in an urge.

Simultaneous multi-determination of pesticide residues in black tea leaves and infusion: a risk assessment study

This study aimed to investigate the concentration of 33 pesticide residues in 60 black tea samples collected from Iran, determine their transfer rate, and assess their health risk during brewing. Pesticide extraction and analysis were performed by using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and gas chromatography/tandem mass spectrometry (GC-MS/MS), respectively. The limits of detection (LOD) and the limits of quantification (LOQ) of pesticides were ranged 0.1-7.26 and 0.8-24 μg/kg for dried tea leaves and 0.03-3.1 and 0.09-10 μg/L for the tea infusion, respectively. The levels of pesticide residue in 52 (86.67%) out of 60 tea samples were above the LOD (0.1-7.26 μg/kg). Twenty four (40%) of the samples contained pesticides in a concentration higher than the maximum residue limit (MRL) set by the European Commission (EC). Seven out of 33 validated pesticides were detected in dried tea leaf samples that only four of seven, including buprofezin, chlorpyrifos, hexaconazole, and triflumizole, were transferred into tea infusion, demonstrating that the concentrations of pesticides in infusion were raised during brewing. The risk assessment study for detected pesticides in the tea infusion samples indicated that this beverage consumption was safe for consumers, while the mean residue of some pesticides in positive samples was higher than the MRL; therefore, periodic control of these pesticides should be regularly implemented.

The degradation and metabolism of chlorfluazuron and flonicamid in tea: A risk assessment from tea garden to cup

Degradation and metabolism of chlorfluazuron and flonicamid from tea garden to cup were simultaneously investigated by a modified QuEChERS method coupled with UPLC-MS/MS quantification. The dissipation half-lives of chlorfluazuron, flonicamid, and total flonicamid (the sum of flonicamid and its metabolites TFNG, TFNA, and TFNA-AM) in fresh tea leaves during tea growth were 6.0 d, 4.8 d, and 8.1 d, respectively. TFNG and TFNA were generated during tea growth. After tea processing, the residues of chlorfluazuron, flonicamid, and its metabolites in black tea were higher than those in green tea. The average processing factors of chlorfluazuron, flonicamid, and total flonicamid in black tea were 2.54, 3.02, and 2.87, respectively, while in green tea they were 2.40, 2.93, and 2.79, respectively. TFNG, TFNA, and TFNA-AM were formed rapidly during the drying step. Considering the influence of water content at various processing steps, the average loss rates of chlorfluazuron, flonicamid, and total flonicamid residue from fresh tea leaves to black tea were 16.7%, 33.8%, and 20.7%, respectively, and 29.6%, 14.0% and 18.2%, respectively, in the case of green tea. The highest leaching rates of chlorfluazuron, flonicamid, and total flonicamid during tea brewing were 6.8%, 97.0%, and 97.4%, respectively, in black tea infusion, and 6.0%, 98.9%, and 98.6%, respectively, in green tea infusion. The metabolites, especially TFNG, had a higher leaching rate during tea brewing. The migration of chlorfluazuron from fresh leaves to tea infusion was low, and the migration of flonicamid was high. The RQc and RQa of chlorfluazuron and total flonicamid were less than 1. This result indicates that the potential dietary intake risk of chlorfluazuron from tea is negligible. However, the risk of total flonicamid intake is three times higher than that of chlorfluazuron. There is a potential risk of intake of flonicamid and its metabolites in tea for human consumption.

Residue dissipation, transfer and safety evaluation of picoxystrobin during tea growing and brewing

BACKGROUND

Picoxystrobin is a new osmotic and systemic broad-spectrum methoxyacrylate fungicide with a good control effect on tea anthracnose, so it has been proposed to spray picoxystrobin before the occurrence and onset of tea anthracnose during tea bud growth in order to protect them. However, there are few reports about the residue analysis method, field dissipation, terminal residue and risk assessment of picoxystrobin in tea. And there is no scientific and reasonable maximum residue limit of picoxystrobin in green tea.

RESULTS

A rapid and sensitive analysis method for picoxystrobin residue in fresh tea leaf, green tea, tea infusion and soil was established by UPLC-MS/MS. The spiked recoveries of picoxystrobin ranged from 73.1% to 111.0%, with relative standard deviations from 1.8% to 9.2%. The limits of quantitation were 20 μg kg^-1 in green tea, 8 μg kg^-1 in fresh tea leaves and soil and 0.16 μg kg^-1 in tea infusion. The dissipation half-lives of picoxystrobin in fresh tea leaf and soil were 2.7-6.8 and 2.5-14.4 days, respectively. And the maximum residue of picoxystrobin in green tea was 15.28 mg kg^-1 with PHI at 10 days for terminal test. The total leaching rate of picoxystrobin during green tea brewing was lower than 35.8%.

CONCLUSIONS

According to safety evaluation, the RQc and RQa values of picoxystrobin in tea after 5 to 14 days for the last application were significantly lower than 1. Therefore, the maximum residue limit value of picoxystrobin in tea that we suggest to set at 20 mg kg^-1 can ensure the safety of tea for human drinking. © 2020 Society of Chemical Industry.

A Review on Prediction Models for Pesticide Use, Transmission, and Its Impacts

The lure of increased productivity and crop yield has caused the imprudent use of pesticides in great quantity that has unfavorably affected environmental health. Pesticides are chemicals intended for avoiding, eliminating, and mitigating any pests that affect the crop. Lack of awareness, improper management, and negligent disposal of pesticide containers have led to the permeation of pesticide residues into the food chain and other environmental pathways, leading to environmental degradation. Sufficient steps must be undertaken at various levels to monitor and ensure judicious use of pesticides. Development of prediction models for optimum use of pesticides, pesticide management, and their impact would be of great help in monitoring and controlling the ill effects of excessive use of pesticides. This paper aims to present an exhaustive review of the prediction models developed and modeling strategies used to optimize the use of pesticides.

A Dissipation Pattern of Gibberellic Acid and Its Metabolite, Isogibberellic Acid, during Tea Planting, Manufacturing, and Brewing

As a widely used plant growth regulator, the gibberellic acid (GA₃) residue in tea has potential risk for human health. Herein, the degradation of GA₃ and its conversion into main metabolites were investigated during tea planting, manufacturing, and brewing using ultrahigh-performance liquid chromatography tandem mass spectrometry. The metabolite iso-GA₃ was first discovered during the tea production chain and identified using Q-Exactive Orbitrap mass spectrometry. GA₃ dissipated following first-order kinetics in tea shoots with half-lives ranging from 2.46 to 2.74 days. It was degraded into iso-GA₃ in tea shoots, which had a longer residual period than GA₃. Meanwhile, external application of GA₃ could increase the proportion of growth-promoting endogenous phytohormones and lead to rapid growth of tea plants. During tea manufacturing, iso-GA₃ was quickly and massively converted from GA₃. Fixing (heat at 220-230 °C) played an important role in the dissipation of GA₃ and iso-GA₃ during green tea manufacturing, but there were high residues of iso-GA₃ in black tea. High transfer rates (77.3 to 94.5%) of GA₃ and iso-GA₃ were observed during tea brewing. These results could provide a practical reference for food safety in tea and other agricultural products and the guidance for scientific application of GA₃ in tea planting.

Temporal variation analysis and risk assessment of neonicotinoid residues from tea in China

The extensive use of neonicotinoids (NEOs) has caused the release of wide-ranging of residues to the environment and food, and their potential health risks are now receiving more attention. In this study, three surveys were conducted to obtain the overall profiles of NEO residue levels (seven NEOs and one metabolite) in Chinese tea over a period of seven years. A total of 726 tea samples were tested, and nearly 87% of the samples were found to have detectable NEO residues. The overall average detection frequency of acetamiprid was the highest, reaching 73%. Imidacloprid residues in 4.6% of the samples exceeded the Chinese maximum residue limits, whereas clothianidin and nitenpyram had been detected in Chinese tea samples since 2014. The applications of thiacloprid and thiamethoxam gradually increased, and some tea samples with high residue levels appeared in China. These findings signal the replacement of new and old varieties of NEOs in China. Both long- and short-term cumulative exposures to NEOs were calculated based on optimistic and pessimistic models recommended in the EFSA guidelines. In the three survey periods, the average total imidacloprid-equivalent concentrations were 484.63, 1713.36, and 1148.34 μg/kg, respectively. Combined with the refined point estimates and probabilistic models used in this study, the hazard quotients of NEO residues in tea for Chinese tea consumers were found to be low and within the bounds of safety.

Residue reduction and risk evaluation of chlorfenapyr residue in tea planting, tea processing, and tea brewing

The chlorfenapyr residues in the entire tea chain, i.e., in tea planting, tea processing, and tea brewing, were systematically investigated. The degradation rate constants of chlorfenapyr in the tea plants ranged from 0.2460 to 0.2870 with the half-life of 2.4-3.0 days, and 87.5-89.9% of the chlorfenapyr in tea shoots dissipated in the interval of 7 days. In the processing process of both black tea and green tea, the chlorfenapyr residue decreased by 59.1-67.6% compared with the residue in tea shoots due to high vapor pressure (1.2 × 10^-2 mPa 25 °C), and drying was the key step that dissipated the chlorfenapyr. A low leaching efficiency of 2.2-3.4% from tea leaves to tea infusion, resulted in low water solubility (0.14 mg L^-1 25 °C), indicated that >90% of the residual chlorfenapyr was eliminated before the intake of tea infusion. On the basis of these results, an extremely large proportion of the chlorfenapyr deposited on tea shoots was degraded during tea planting, tea processing, and tea brewing, and the health risk was reduced primarily in the first and the last step rather than during tea processing. The remaining 0.2% chlorfenapyr sprayed on the tea shoots represents a negligible health risk based on the RQ assessment. The pesticides with high vapor pressure and low water solubility were more recommended in tea garden for pest control.

Systematic probabilistic risk assessment of pesticide residues in tea leaves

Multiple pesticide residues are frequently present in tea leaves and while the majority of residues satisfy Taiwan's current health regulations, there are potential health effects from pesticide exposure that are of great concern for tea drinkers. We undertook a systematic probabilistic risk assessment of 59 pesticides in tea leaves from 1629 tea leaf samples obtained by Taiwan's Food and Drug Administration in two monitoring surveys in 2015. Bayesian statistics used a Markov Chain Monte Carlo approach to estimate posterior distributions of pesticide residues in tea leaves, lifetime average daily doses and hazard quotients (HQs) of evaluated pesticides. We classified 95th percentile values of HQs into three categories: 0 < HQ < 0.5, 0.5 ≤ HQ ≤ 1 and 1 < HQ. The 95th percentiles of HQs for triazophos (3.39), carbofuran (2.04) and endosulfan (1.80) exceeded 1 in the adult population; the HQ for 3-OH carbofuran was 0.97 and was less than 0.5 for the remaining 55 pesticides. The health risk posed by pesticide residues for tea drinkers is negligible, if triazophos, carbofuran, endosulfan, and 3-OH carbofuran residues satisfy regulatory standards. However, five legacy pesticides, DDT, methomyl, carbofuran, dicofol and endosulfan, were identified. To reduce uncertainties, this study combined Bayesian statistics with a mode of action approach for systematic risk assessment of co-exposure to multiple pesticide residues in tea leaf samples. Measuring pesticide transfer rates will improve the quality of future risk assessments concerning residues in tea leaves. Appropriate management of pesticides in Taiwanese tea farms and monitoring of pesticide residues in imported tea is warranted to protect Taiwan's tea drinkers.

Method validation for bifenthrin emulsifiable concentrate and uncertainty calculation using gas chromatographic approach

Background

Bifenthrin is the third-generation synthetic pyrethroid insecticide having an effective control on the pest of cotton, vegetable, and fruits. This study is focused on the validation of the test procedure for the quantitative determination of bifenthrin contents in the emulsifiable concentrate and measurement of uncertainty. The purpose of this validation procedure is to demonstrate that it is suitable for the intended use. This was determined by gas chromatography with a flame ionization detector (FID). The estimation was carried out on Shimadzu GC equipped with TRB-5 (95% dimethyl, 5% diphenyl polysiloxane) column using a nitrogen carrier gas.

Results

Different parameters of validation (precision, accuracy, linearity, specificity, selectivity, and robustness) were executed. All steps of method validation were performed, and its uncertainty is determined. The method is simple, selective, accurate, precise, cost-effective, and suitable. The validation parameters are based on harmonized guidelines on the validation of the analytical test method.

Conclusions

Pesticide formulation bodies can use this method for the qualitative and quantitative determination of bifenthrin different formulations. These data verify that the method is validated, and all results are in an acceptable limit. The method is developed on GC. Moreover, the analysis time is also short as compared to that of HPLC. The developed method is simple reliable and has a realistic approach.