Dissipation Residue Behaviors and Dietary Risk Assessment of Boscalid and Pyraclostrobin in Watermelon by HPLC-MS/MS

Assessment of the Dissipation Behaviors, Residues, and Dietary Risk of Oxine-Copper in Cucumber and Watermelon by UPLC-MS/MS

During production, agricultural products are often susceptible to potential harm caused by residual traces of pesticides. Oxine-copper is a broad spectrum and efficient protective fungicide widely used in the production of fruits and vegetables. The present study was carried out to profile the dissipation behaviors and residues of oxine-copper on cucumber and watermelon using QuEChERS pretreatment and UPLC-MS/MS. Its storage stability and dietary risk assessment were also estimated. The method validation displayed good linearity (R 2 ≥ 0.9980), sensitivity (limits of quantification ≤0.01 mg/kg), and recoveries (75.5-95.8%) with relative standard deviations of 2.27-8.26%. According to first-order kinetics, the half-lives of oxine-copper in cucumber and watermelon were 1.77-2.11 and 3.57-4.68 d, respectively. The terminal residues of oxine-copper in cucumber and watermelon samples were within <0.01-0.264 and <0.01-0.0641 mg/kg, respectively. Based on dietary risk assessment, the estimated long-term dietary risk probability value of oxine-copper in cucumber and watermelon is 64.11%, indicating that long-term consumption of cucumber and watermelon contaminated with oxine-copper would not pose dietary risks to the general population. The results provide scientific guidance for the rational utilization of oxine-copper in field ecosystems of cucumber and watermelon.

Cellulose Nanofiber Platform for Pesticide Sequestration in the Gastrointestinal Tract

Exploitation of nature-derived materials is an important approach to promote environmental sustainability. Among these materials, cellulose is of particular interest due to its abundance and relative ease of access. As a food ingredient, cellulose nanofibers (CNFs) have found interesting applications as emulsifiers and modulators of lipid digestion and absorption. In this report, we show that CNFs can also be modified to modulate the bioavailability of toxins, such as pesticides, in the gastrointestinal tract (GIT) by forming inclusion complexes and promoting interaction with surface hydroxyl groups. CNFs were successfully functionalized with (2-hydroxypropyl)-β-cyclodextrin (HPBCD) using citric acid as a crosslinker via esterification. Functionally, the potential for pristine and functionalized CNFs (FCNFs) to interact with a model pesticide, boscalid, was tested. Based on direct interaction studies, adsorption of boscalid saturated at around 3.09% on CNFs and at 12.62% on FCNFs. Using an in vitro GIT simulation platform, the adsorption of boscalid on CNFs/FCNFs was also studied. The presence of a high-fat food model was found to have a positive effect in binding boscalid in a simulated intestinal fluid environment. In addition, FCNFs were found to have a greater effect in retarding triglyceride digestion than CNFs (61% vs 30.6%). Overall, FCNFs were demonstrated to evoke synergistic effects of reducing fat absorption and pesticide bioavailability through inclusion complex formation and the additional binding of the pesticide onto surface hydroxyl groups on HPBCD. By adopting food-compatible materials and processes for production, FCNFs have the potential to be developed into a functional food ingredient for modulating food digestion and the uptake of toxins.

Residual Behavior and Dietary Risk Assessment of Chlorfenapyr and Its Metabolites in Radish

Chlorfenapyr, as a highly effective and low-toxicity insect growth regulation inhibitor, has been used to control cross-cruciferous vegetable pests. However, the pesticide residue caused by its application threatens human health. In this paper, the residue digestion and final residue of chlorfenapyr in radish were studied in a field experiment. The results of the dynamic digestion test showed that the half-life of chlorfenapyr in radish leaves ranged from 6.0 to 6.4 days, and the digestion rate was fast. The median residual values of chlorfenapyr in radish and radish leaves at 14 days after treatment were 0.12 and 3.92 mg/kg, respectively. The results of the dietary intake risk assessment showed that the national estimated daily intake (NEDI) of chlorfenapyr in various populations in China were 0.373 and 5.66 µg/(kg bw·d), respectively. The risk entropy (RQ) was 0.012 and 0.147, respectively, indicating that the chronic dietary intake risk of chlorfenapyr in radish was low. The results of this study provided data support and a theoretical basis for guiding the scientific use of chlorfenapyr in radish production and evaluating the dietary risk of chlorfenapyr in vegetables.

Dissipation and Residue of Metalaxyl-M and Azoxystrobin in Scallions and Cumulative Risk Assessment of Dietary Exposure to Hepatotoxicity

Metalaxyl-M and azoxystrobin have been used to control various fungal diseases on scallion and other crops. In view of the adverse toxic effects of both on the mammalian liver, it is necessary to conduct a cumulative risk assessment of their dietary exposure to consumers. The residues of metalaxyl-M and azoxystrobin on scallion were determined by a quick, easy, cheap, effective, rugged, and safe method (QuEChERS) combined with high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS). The half-lives were about 1.15 and 3.89 days, respectively, and the final residues after a seven-day harvest interval were <0.001−0.088 mg/kg and 0.190−4.687 mg/kg, respectively. The cumulative dietary risk quotient of the two fungicides to Chinese consumers calculated by the probability model is 13.94%~41.25%. According to the results of the contribution analysis, the risk posed by azoxystrobin is much greater than that of metalaxyl-M. Although metalaxyl-M and azoxystrobin do not pose a cumulative risk to Chinese consumers, the risk to children and adolescents is significantly higher than that to adults. This suggests that in future research, more consideration should be given to the cumulative risk of compounds to vulnerable groups.