Study on degradation behaviour, residue distribution, and dietary risk assessment of propiconazole in celery and onion under field application

An updated status of currently used pesticides in India: Human dietary exposure from an Indian food basket

Currently used pesticides (CUPs) were introduced to have lower persistence and bioaccumulation, and lesser bioavailability towards non-target species. Nevertheless, CUPs still represent a concern for both human health and the environment. India is an important agricultural country experiencing a conversion from the use of obsolete organochlorine pesticides to a newer generation of phytosanitary products. As for other developing countries, very little is known about the transfer of CUPs to the human diet in India, where systematic monitoring is not in place. In this study, we analyzed ninety four CUPs and detected thirty CUPs in several food products belonging to five types: cereals and pulses, vegetables, fruits, animal-based foods, and water. Samples were taken from markets in Delhi (aggregating food produced all over India) and in the periurban area of Dehradun (northern India) (representing food produced locally and through more traditional practices). Overall, chlorpyrifos and chlorpropham were the most detected CUPs with a detection frequency of 33% and 25%, respectively. Except for vegetables and fruits, the levels of CUPs in all other food types were significantly higher in samples from Delhi (p < 0.05). Exposure dosage of CUPs through different food matrices was calculated, and chlorpropham detected in potatoes had the maximum exposure dosage to humans (2.46 × 10-6 mg/kg/day). Risk analysis based on the hazard quotient technique indicated that chlorpyrifos in rice (2.76 × 10-2) can be a concern.

Degradation Dynamics and Residue Analysis of Four Propiconazole Stereoisomers in "Fengtang" Plum during Storage by LC-MS/MS

Herein, an accurate and sensitive method was developed for detecting four stereoisomers of propiconazole in "Fengtang" plum by LC-MS/MS. The mean recovery of four propiconazole stereoisomers ranged from 79.42 to 104.10% at three adding levels with reasonable RSD of 1.54-11.68%, and the LOD and LOQ of the four stereoisomers was 0.0005 mg/kg and 0.004 mg/kg, respectively. In addition, the residue and selective degradation of propiconazole stereoisomers in plums were investigated by storage at 20 °C and 4 °C. The half-lives of propiconazole stereoisomeric during storage were 9.49-15.40 d at 20 °C, and 21.00-28.88 d at 4 °C. The degradation of (2R,4R)-propiconazole and (2R,4S)-propiconazole in stored plums was slightly slower than that of the corresponding enantiomers (2S,4S)-propiconazole and (2S,4R)-propiconazole. The total residues of propiconazole were 0.026-0.487 mg/kg in the plum storage period, and the water washing could remove 49.35% to 54.65% of the propiconazole residue in plum. The hardness of plums treated with propiconazole was generally higher than that of control in the middle and late stages of storage. The effects of propiconazole on the total soluble solid content of plums were different at 20 °C and 4 °C. This study provides a scientific reference for the food safety evaluation of the "Fengtang" plum after the application of propiconazole during the storage period.

Degradation and residues of mandipropamid in soil and ginseng and dietary risk assessment in Chinese culture

Mandipropamid, a new fungicide for oomycete disease, has a strong effect on the blight of many crops and has been registered for the treatment of ginseng blight in China. However, no maximum residue limit (MRL) of mandipropamid has been identified for ginseng, and there have been few related studies. We established and verified the analysis method of mandipropamid in ginseng using high-performance liquid chromatography-tandem mass spectrometry. The method has good linearity and accuracy in the range of 0.002-0.5 mg/kg. The average recovery of mandipropamid was 87.4-101.6%, and the standard deviation was 1.1-4.0. Mandipropamid in ginseng plants and soil rapidly degraded following first-order kinetics models. The degradation dynamics showed that the half-life of mandipropamid in ginseng plant and soil was 13.8-28.0 and 9.8-27.4 d, respectively. After the recommended dose of mandipropamid was applied once, the residual content of mandipropamid in fresh ginseng, dried ginseng, red ginseng, ginseng plant, and ginseng soil was < 0.01-0.185, < 0.01-0.265, 0.085-1.544, 0.075-4.800, and < 0.01-0.014 mg/kg, respectively. The dietary risk assessment of mandipropamid on ginseng showed that the risk quotient value was far less than 100%, indicating that the recommended dose of mandipropamid does not cause unacceptable risks to humans. After the recommended dose of mandipropamid was applied once, it did not cause unacceptable risks to humans. This study not only provides a reasonable spray dosage of mandipropamid to ginseng but also offers a reference for the establishment of MRLs in China.

Parental exposure to propiconazole at environmentally relevant concentrations induces thyroid and metabolism disruption in zebrafish (Danio rerio) offspring: An in vivo, in silico and in vitro study

Propiconazole is used against fungal growth in agriculture and is released into the environment, but is a potential health threat to aquatic organisms. Propiconazole induces a generational effect on zebrafish, although the toxic mechanisms involved have not been described. The aim of this study was to investigate the potential mechanisms of abnormal offspring development after propiconazole exposure in zebrafish parents. Zebrafish were exposed to propiconazole at environmentally realistic concentrations (0.1, 5, and 250 μg/L) for 100 days and their offspring were grown in control solution for further study. Heart rate, hatching rate, and body length of hatched offspring were reduced. An increase in triiodothyronine (T₃) content and the T₃/T₄ (tetraiodothyronine) ratio was observed, indicating disruption of thyroid hormones. Increased protein level of transthyretin (TTR) in vivo was consistent with the in silico molecular docking results and T₄ competitive binding in vitro assay, suggests higher binding affinity between propiconazole and TTR, more than with T₄. Increased expression of genes related to the hypothalamus-pituitary-thyroid (HPT) axis and altered metabolite levels may have affected offspring development. These findings emphasizes that propiconazole, even on indirect exposure, represents health and environmental risk that should not be ignored.

Effect of propiconazole on plastic film microplastic degradation: Focusing on the change in microplastic morphology and heavy metal distribution

With the rapid increase in the use of plastic films, microplastic (MP) pollution in agricultural soils has become a global environmental problem. Propiconazole is widely used in agriculture and horticulture; however, its role in plastic film degradation remains elusive. Butylene adipate-co-terephthalate (PBAT) and polyethylene (PE) films were used to analyze the effects of propiconazole on plastic film and MP degradation. We identified the surface morphologies of PBAT and PE at different propiconazole concentrations and soil pH values, as well as the adsorption and release characteristics of heavy metals during the degradation process via scanning electron microscopy, Fourier transform infrared spectroscopy and inductively coupled plasma mass spectrometry. Propiconazole accelerated the degradation of MPs, adsorption of heavy metals (Ni and Zn), and release of Sn at low concentrations (≤40 mg/kg); however, these effects were evidently absent at a high concentration (120 mg/kg). Furthermore, MPs were more prone to degradation in acidic or alkaline soils than in neutral soil when they coexisted with propiconazole. Hence, we suggest that PBAT and PE plastic films may not be suitable for application in acidic and alkaline soils with propiconazole, because of shorter rupture time and more heavy metal adsorption. PBAT degraded faster, absorbed and released more heavy metals than PE. Under all tested conditions, the heavy metal contents in MPs gradually approached those in soil, which proves that MPs are carriers of heavy metal pollutants. These results may help in assessing the impact of MPs on soil environments and provide a theoretical basis for the standardized propiconazole and plastic film usage.

Residue and Risk Assessment of Imidacloprid and Chlorantraniliprole in Open Field and Greenhouse Celery

ABSTRACT

The residue levels and risk assessment of imidacloprid (IMI) and chlorantraniliprole (CAP) in celery grown under open field and greenhouse cultivation were investigated. Both pesticides were used through foliar application and soil drench application at the recommended dose (RD) and 10-fold recommended dose (10RD). The half-lives of IMI and CAP in celery were 1.9 to 5.8 days and 4.3 to 6.5 days after foliar application, respectively, and the dietary risk quotients of IMI and CAP were 14.8 to 18.3% and 1.0 to 1.2%, respectively. For soil drench application, the half-lives of IMI and CAP in soil were 17.5 to 28.5 days and 15.1 to 23.7 days, respectively. Celery plants were able to absorb both insecticides from the soil. The highest concentrations of IMI in celery plants were 0.12 to 0.24 mg kg-1 (RD) and 0.34 to 0.39 mg kg-1 (10RD), and those for CAP were 0.0081 to 0.015 mg kg-1 (RD) and 0.028 to 0.057 mg kg-1 (10RD). Based on the highest residues of IMI and CAP in celery, the dietary risk quotients of IMI and CAP were 15.0% (RD) to 15.6% (10RD) and 1.0% (RD and 10RD) after soil drench application, respectively. The observed bioconcentration factors were 1.38 to 2.11 (IMI) and 0.35 to 0.48 (CAP), indicating that celery accumulated IMI more easily than CAP. The foliar and soil applications of IMI and CAP in celery at the RD and 10RD do not pose a safety risk to consumers.

HIGHLIGHTS

Four Propiconazole Stereoisomers: Stereoselective Bioactivity, Separation via Liquid Chromatography-Tandem Mass Spectrometry, and Dissipation in Banana Leaves

In this study, we evaluated the stereoselective bioactivity of four propiconazole stereoisomers against the causal agents of the banana leaf spot disease (Curvularia lunata and Colletotrichum musae). We also evaluated the stereoselective degradation of the stereoisomers in banana leaves under field test conditions. The Superchiral S-OX column successfully separated the four propiconazole stereoisomers. X-ray single-crystal diffraction confirmed that the absolute configuration of the cis-stereoisomer-(+)-A of propiconazole was (2R,4S)-propiconazole and that of the cis-stereoisomer-(-)-A of propiconazole was (2S,4R)-propiconazole. In vitro antibacterial results revealed that (2R,4S)-(+)-propiconazole had the highest activity against the two target plant fungi. In this study, a new and efficient high-performance liquid chromatography tandem mass spectrometry method was developed for the determination of the four stereoisomeric residues of propiconazole in banana leaves. The mean recoveries of the method for the stereoisomers were 76.3-103% with relative standard deviations of 1.25-11.4%. The four propiconazole stereoisomers had a detection limit of 0.002-0.006 mg/kg and a limit of quantification of 0.02-0.03 mg/kg in banana leaves. Propiconazole-(-)-B and propiconazole-(-)-A degraded slightly faster than their corresponding enantiomers propiconazole-(+)-B and propiconazole-(+)-A in banana leaves collected from three typical banana production areas.

Antibody Generation and Rapid Immunochromatography Using Time-Resolved Fluorescence Microspheres for Propiconazole: Fungicide Abused as Growth Regulator in Vegetable

Propiconazole (PCZ) is a fungicide popularly used to prevent and control wheat and rice bakanae disease, etc. However, it was recently found to be illegally employed as a plant regulator to induce thick stems and dark green leaves of Brassica campestris, a famous vegetable in Guangdong, South China. Due to a lack of available recognition molecules to the target analyte, it is still a big challenge to establish a rapid surveillance screening method. In this study, a novel chiral hapten was rationally designed, and an artificial immunogen was then prepared for the generation of a specific antibody against propiconazole for the first time. Using the obtained antibody, a highly sensitive time-resolved fluorescence microspheres lateral flow immunochromatographic assay (TRFMs-LFIA) was established with a visual limit of detection of 100 ng/mL and a quantitative limit of detection of 1.92 ng/mL for propiconazole. TRFMs-LFIA also exhibited good recoveries ranging from 78.6% to 110.7% with coefficients of variation below 16%. The analysis of blind real-life samples showed a good agreement with results obtained using HPLC-MS/MS. Therefore, the proposed method could be used as an ideal screening surveillance tool for the detection of propiconazole in vegetables.

Monitoring residue levels and dietary risk assessment of thiamethoxam and its metabolite clothianidin for Chinese consumption of Chinese kale

BACKGROUND

Thiamethoxam is widely used to control pests in Chinese kale, popularly consumed leafy vegetables. The potential risk to the environment and human health has aroused much public concern. Therefore, it is important to investigate the degradation behavior, residue distribution and dietary risk assessment of thiamethoxam in Chinese kale.

RESULTS

A sensitive analytical method for determination of thiamethoxam and its metabolite clothianidin residue in Chinese kale was established and validated through a quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The recoveries were 85.4-101.2% for thiamethoxam and 79.5-108.1% for clothianidin, with the relative standard deviations (RSDs) of 0.9-10.2% and 1.8-6.0%, respectively. For the dissipation kinetics, the data showed that thiamethoxam in Chinese kale was degraded with the half-lives of 4.1 to 4.5 days. In the terminal residue experiments, the residues of thiamethoxam were 0.017-0.357 mg kg^-1 after application 2-3 times with a preharvest interval (PHI) of 7 days under the designed dosages. The chronic and acute dietary exposure assessment risk quotient (RQ) values of thiamethoxam in Chinese kale for different Chinese consumers were 0.08-0.19% and 0.05-0.12%, respectively, and those of clothianidin were 0.01-0.04% and 0.02-0.04%, respectively, all of the RQ values were lower than 100%.

CONCLUSION

Thiamethoxam in Chinese kale was rapidly degraded following first-order kinetics models. The dietary risk of thiamethoxam and clothianidin through Chinese kale was negligible to consumers. The results from this study are important reference for Chinese governments to developing criteria for the safe and rational use of thiamethoxam, setting maximum residue levels (MRLs), monitoring the quality safety of agricultural products and protecting consumer health. © 2021 Society of Chemical Industry.

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.

Pesticide Residue Behavior and Risk Assessment in Celery after Se Nanoparticles Application

This study investigates pesticide levels in celery, and compares their degradation, dissipation, distribution, and dietary risk after spraying with selenium (Se) nanoparticles. Abamectin, imidacloprid, acetamiprid, thiamethoxam, and lambda-cyhalothrin were sprayed at 1.6, 6.8, 2.0, 1.0, and 0.7 g a.i. ha⁻¹ followed by a 2 g·ha⁻¹ Se nanoparticle application during the growing period. Thiamethoxam, abamectin, imidacloprid, lambda-cyhalothrin, and acetamiprid in celery degraded following a first order kinetic model after 2 g·ha⁻¹ Se nanoparticles application. With the exception of acetamiprid, the half-lives of thiamethoxam, abamectin, imidacloprid, and lambda-cyhalothrin were reduced from 2.4, 0.5, 1.2, 4.2 days without Se nanoparticles application to 1.4, 0.2, 0.9, 3.7 days with the addition of Se nanoparticles (2 g·ha⁻¹), respectively. The chronic dietary exposure risk probability (RQc) and the acute dietary exposure risk probability (RQa) of celery after Se nanoparticles application were within acceptable limits for consumption except for abamectin.

Recent Advances in Bioactive Compounds, Health Functions, and Safety Concerns of Onion (Allium cepa L.)

Onion (Allium cepa L.) is a common vegetable, widely consumed all over the world. Onion contains diverse phytochemicals, including organosulfur compounds, phenolic compounds, polysaccharides, and saponins. The phenolic and sulfur-containing compounds, including onionin A, cysteine sulfoxides, quercetin, and quercetin glucosides, are the major bioactive constituents of onion. Accumulated studies have revealed that onion and its bioactive compounds possess various health functions, such as antioxidant, antimicrobial, anti-inflammatory, anti-obesity, anti-diabetic, anticancer, cardiovascular protective, neuroprotective, hepatorenal protective, respiratory protective, digestive system protective, reproductive protective, and immunomodulatory properties. Herein, the main bioactive compounds in onion are summarized, followed by intensively discussing its major health functions as well as relevant molecular mechanisms. Moreover, the potential safety concerns about onion contamination and the ways to mitigate these issues are also discussed. We hope that this paper can attract broader attention to onion and its bioactive compounds, which are promising ingredients in the development of functional foods and nutraceuticals for preventing and managing certain chronic diseases.

Residue changes and processing factors of eighteen field-applied pesticides during the production of Chinese Baijiu from rice

The fate of eighteen pesticides in field-collected rice samples during Chinese Baijiu production was systematically studied. The results indicated that steeping decreased flonicamid residue by 73.2% due to its high water-solubility and low octanol/water partition coefficient. The steaming step reduced pesticide residues by 32.0%-75.3% through evaporation or thermal degradation. After steaming, the pesticide residues were further reduced by 39.8-74.2% in fermentation which might be caused by biological degradation. In addition, distillation was shown to be most effective, responsible for greater than 90% losses of the remaining pesticide residues. The processing factors (PFs) were generally lower than 1 for different processes and the whole procedure. These results revealed that the procedure of Chinese Baijiu production could dramatically decrease residues of all the eighteen pesticides. Overall, this study provide important references for monitoring pesticide residue levels during the production of Chinese Baijiu from rice, and ensuring proper risk assessment from pesticide contamination.