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

Residue pattern and risk assessment of validamycin A and spinosyn A in tea using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry

Validamycin A (VA) and spinosyn A (SA) have been utilized as antibiotic pesticides in tea plantations for the control of pests and diseases. Both pesticides pose significant risks to human health and have been listed as key controlled new pollutants in China. So far, there have been few reports for the risk assessment of antibiotic pesticides in tea. In this study, a hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry (HILIC-MS/MS) method was developed for the simultaneous detection of VA and SA residues in tea. Method validation demonstrated good accuracy and precision. During tea planting, SA and VA in tea shoots degraded fast, with the half-life of 0.36 to 0.43 days for SA and 0.72 to 0.92 days for VA. SA and VA in tea shoots degraded fast initially and then followed by a slower phase. Both SA and VA degraded rapidly during the withering and drying stages. Compared to green tea, the degradation rates of both pesticides were faster during black tea manufacturing. Transfer rates of VA and SA from tea into infusions had transfer rates of 76.7 % to 99.5 % and 1.5 % to 2.7 %, respectively. The chronic risk quotient (RQc) < 1 for both antibiotic pesticides indicated negligible consumer risk from tea.

Chitosan-oligosaccharide alleviates chlorpyrifos-induced biochemical and developmental toxicity and reduces its accumulation in wheat (Triticum aestivum L.)

Chlorpyrifos (CHP) contamination affects agricultural land and poses significant risks to plants and humans. Chitosan-oligosaccharide (COS) enhances plant resilience under stress and boosts the activity of enzymes metabolizing exogenous substances. This study aimed to explore the potential and mechanism of COS in mitigating CHP phytotoxicity and reducing CHP accumulation through both pot and field experiments. The results indicated that CHP exposure caused oxidative stress and decreased photosynthesis by 18.5 % in wheat. COS up-regulated the expression of antioxidant enzyme genes in CHP-stressed plants, resulting in a 12.1 %-29.4 % increase in antioxidant enzyme activity, which resulted in an 11.3 %-12.8 % reduction in reactive oxygen species (ROS) and an 11.5 %-14.7 % reduction in malondialdehyde (MDA) content in leaves and roots, respectively. Additionally, COS increased chlorophyll content by 6.6 % by regulating genes related to chlorophyll metabolism, enhancing photosynthesis by 13.6 %. COS also reduced CHP uptake and accelerated its metabolism by upregulating CYP450, GST, and lignin biosynthesis-related genes. Wheat treated with COS exhibited a 26.7 %-28.7 % reduction in grains' CHP content, resulting in a lower health risk index (HRI). These findings provide novel insights into the potential of COS in alleviating CHP phytotoxicity and reducing its accumulation.

Assessing environmental and human health risks: Insight from the enantioselective metabolism and degradation of fenpropidin

Fenpropidin (FPD), a widely employed chiral fungicide, is frequently detected in diverse environments. In an in vitro rat liver microsomes cultivation (RLMs), the metabolism exhibited the order of R-FPD > S-FPD, with respective half-lives of 10.42 ± 0.11 and 12.06 ± 0.15 min, aligning with kinetic analysis results. CYP3A2 has been demonstrated to be the most significant oxidative enzyme through CYP450 enzyme inhibition experiments. Molecular dynamics simulations unveiled the enantioselective metabolic mechanism, demonstrating that R-FPD forms hydrogen bonds with the CYP3A2 protein, resulting in a higher binding affinity (-6.58 kcal mol-1) than S-FPD. Seven new metabolites were identified by Liquid chromatography time-of-flight high-resolution mass spectrometry, which were mainly generated through oxidation, reduction, hydroxylation, and N-dealkylation reactions. The toxicity of the major metabolites predicted by the TEST procedure was found to be stronger than the predicted toxicity of FPD. Moreover, the enantioselective fate of FPD was studied by examining its degradation in three soils with varying physical and chemical properties under aerobic, anaerobic, and sterile conditions. Enantioselective degradation of FPD occurred in soils without enantiomeric transformation, displaying a preference for R-FPD degradation. R-FPD is a low-risk stereoisomer both in the environment and in mammals. The research presented a systematic and comprehensive method for analyzing the metabolic and degradation system of FPD enantiomers. This approach aids in understanding the behavior of FPD in the environment and provides valuable insights into their potential risks to human health.

Pest recognition in microstates state: an improvement of YOLOv7 based on Spatial and Channel Reconstruction Convolution for feature redundancy and vision transformer with Bi-Level Routing Attention

Introduction

In order to solve the problem of precise identification and counting of tea pests, this study has proposed a novel tea pest identification method based on improved YOLOv7 network.

Methods

This method used MPDIoU to optimize the original loss function, which improved the convergence speed of the model and simplifies the calculation process. Replace part of the network structure of the original model using Spatial and Channel reconstruction Convolution to reduce redundant features, lower the complexity of the model, and reduce computational costs. The Vision Transformer with Bi-Level Routing Attention has been incorporated to enhance the flexibility of model calculation allocation and content perception.

Results

The experimental results revealed that the enhanced YOLOv7 model significantly boosted Precision, Recall, F1, and mAP by 5.68%, 5.14%, 5.41%, and 2.58% respectively, compared to the original YOLOv7. Furthermore, when compared to deep learning networks such as SSD, Faster Region-based Convolutional Neural Network (RCNN), and the original YOLOv7, this method proves to be superior while being externally validated. It exhibited a noticeable improvement in the FPS rates, with increments of 5.75 HZ, 34.42 HZ, and 25.44 HZ respectively. Moreover, the mAP for actual detection experiences significant enhancements, with respective increases of 2.49%, 12.26%, and 7.26%. Additionally, the parameter size is reduced by 1.39 G relative to the original model.

Discussion

The improved model can not only identify and count tea pests efficiently and accurately, but also has the characteristics of high recognition rate, low parameters and high detection speed. It is of great significance to achieve realize the intelligent and precise prevention and control of tea pests.

Magnetic Relaxation Switching Immunosensors via a Click Chemistry-Mediated Controllable Aggregation Strategy for Direct Detection of Chlorpyrifos

Chlorpyrifos (CPF) is the most frequently found organophosphate pesticide residue in solid food samples and can cause increasing public concerns about potential risks to human health. Traditional detection signals of such small molecules are mostly generated by target-mediated indirect conversion, which tends to be detrimental to sensitivity and accuracy. Herein, a novel magnetic relaxation switching detection platform was developed for target-mediated direct and sensitive detection of CPF with a controllable aggregation strategy based on a bioorthogonal ligation reaction between tetrazine (Tz) and trans-cyclooctene (TCO) ligands. Under optimal conditions, this sensor can achieve a detection limit of 37 pg/mL with a broad linear range of 0.1-500 ng/mL in 45 min, which is approximately 51-fold lower than that of the gas chromatography analysis and 13-fold lower than that of the enzyme-linked immunosorbent assay. The proposed click chemistry-mediated controllable aggregation strategy is direct, rapid, and sensitive, indicating great potential for residue screening in food matrices.

Persistence behavior of chlorpyrifos and biological toxicity mechanism to cucumbers under greenhouse conditions

Chlorpyrifos, a broadly utilized insecticide, inhibits many cellular and physiological processes in plants. Here, the phyto-toxicity of chlorpyrifos on cucumber plants, as well as the dissipation kinetics of chlorpyrifos in leaves, were investigated. Those results showed that chlorpyrifos accumulated primarily in the leaves under normal agrochemical spraying conditions with the half-lives among 2.48-4.59 days. Residues of the primary metabolite, 3,5,6-trichloro-2-pyridinol (TCP), rapidly accumulated in plant tissues and soil with chlorpyrifos degradation. The application amount of chlorpyrifos had a significant effect on the persistence of chlorpyrifos and TCP in both plant and soil environments. Chlorpyrifos generated excessive reactive oxygen species (ROS) and malondialdehyde (MDA), which led to oxidative damage. High chlorpyrifos stress even inhibited antioxidant enzymes. The photosynthetic system and gas exchange were suppressed, which ultimately lead to inefficient light use under chlorpyrifos stress. Morphological results revealed that chlorpyrifos induced membrane damage and harmed organelles such as mitochondria and chloroplast. Noninvasive micro-test technology (NMT) showed that chlorpyrifos promoted intracellular Ca²⁺ influx and efflux of H⁺ and K⁺. The Ca²⁺ influx was significantly stimulated after both high and low chlorpyrifos treatment with the minimum value of - 336.33 pmol·cm^-2·s^-1 at 258 s and - 155.68 pmol·cm^-2·s^-1 at 288 s, respectively. Chlorpyrifos stress reversed the H⁺ influx to an efflux in cucumber mesophyll with the mean value of 0.45 ± 0.03 pmol·cm^-2·s^-1 and 0.19 ± 0.03 pmol·cm^-2·s^-1 in cucumber plants under low and high chlorpyrifos stress. High chlorpyrifos stress dramatically increase K⁺ efflux in cucumber leaves by 13.68 times higher than the control. We suggest that ion homeostasis destruction, accompanied by ROS, resulted in oxidative damage to the mesophyll cell of cucumber seedlings.

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.