Photodegradation of the novel herbicide pyraclonil in aqueous solution: Kinetics, identification of photoproducts, mechanism, and toxicity assessment.

Pyraclonil is a new type of pyrazole herbicide, whose photochemical fate in aqueous solution has not been reported yet. In this study, effects on the photolysis rate such as light source, pH, NO3-, Fe3+, fulvic acid (FA) and riboflavin (RF) were investigated. Pyraclonil photodegraded in pure water under both UV and simulated sunlight with half-lives of 32.29 min and 42.52 h, respectively. Under UV, the degradation rate of pyraclonil in pH 4 solution (0.0299 ± 0.0033 min-1) was about twice higher than that in pH 9 (0.0160 ± 0.0063 min-1). Under simulated sunlight, low concentration (0.1-1 mg/L) of FA, NO3-, Fe3+ and RF noticeably promoted the photodegradation of pyraclonil. Then, with the combination of experimental UPLC-Q-TOF/MS and computational calculation of density functional theory (DFT), fourteen transformation products (TPs) of pyraclonil were identified with possible mechanism of C-N bond cleavage, photorearrangement, demethylation, hydroxylation and oxidation. Additionally, acute toxicity assessment was conducted through ECOSAR prediction and laboratory bioassays. The prediction results indicated that toxicity of TP157 to daphnid and green algae was 1.3 and 1.4 times higher than that of the parent, respectively. The bioassay results indicated that toxicities of TP157 and TP263 to C. vulgaris were about 1.6 and 5.9 times higher than that of the parent, respectively. The results provided a reference for elucidating the potential hazards of pyraclonil to non-target organisms and promoting its rational use.

Multi-residue monitoring and dietary risk assessment of 17 pesticides and 3 related metabolites in rice and rice flour from markets in China.

Pesticide residues in rice have attracted widespread public attention in recent years. This research aimed to monitor the residues of 17 pesticides and their 3 metabolites in 120 samples of rice and rice flour collected from markets in China using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) pretreatment method combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The monitoring results showed that isoprothiolane, tricyclazole, fenoxanil, and tebuconazole were detected in the rice samples, with detection frequencies of 33.3%, 17.5%, 8.3%, and 2.5%, and concentrations ranging from 0.02 to 0.1 mg/kg (median = 0.04), 0.01 to 0.17 mg/kg (median = 0.14), 0.04 to 0.06 mg/kg (median = 0.05), and 0.01 to 0.02 mg/kg (median = 0.01), respectively. The residues of these four pesticides were all below their corresponding maximum residue levels (MRLs) set by China. Additionally, isoprothiolane, tricyclazole, fenoxanil, and tebuconazole were detected in rice flour samples, with detection frequencies of 74.2%, 55.0%, 5.0%, and 2.5%, and concentrations ranging from 0.01 to 0.1 mg/kg (median = 0.04), 0.01 to 0.04 mg/kg (median = 0.02), 0.01 to 0.06 mg/kg (median = 0.03), and 0.02 to 0.04 mg/kg (median = 0.03), respectively. Furthermore, the chronic dietary intake risk (HQc), the acute dietary intake risk (HQa), and cumulative dietary risk (HI) for all the detected pesticides were evaluated and found well below 100%, indicating that the dietary intake risks would not pose potential health risks.

Residue levels and risk assessment of acetamiprid-pyridaben mixtures in cabbage under various open field conditions.

Acetamiprid and pyridaben are highly efficient insecticides widely used to protect leafy vegetables against various pests, such as Phyllotreta striolata, but analyses of their residual behaviors applied in mixtures in cabbage fields are primarily lacking. Herein, field trials were performed by spraying 50% acetamiprid-pyridaben wettable powder (50% WP) once at a dose of 150 g of active ingredient per hectare in 12 representative provinces of China under Good Agricultural Practices. The residues of acetamiprid and pyridaben were detected using modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) and liquid chromatography-tandem mass spectrometry, together with an assessment of their dietary risks. The average recoveries of the two insecticides were 84.6-104%, and the relative standard deviations were 0.898-10.1%. The residual concentrations of acetamiprid and pyridaben at the preharvest interval of 7 days were <0.364 and 0.972 mg/kg, respectively, and less than their maximum residue limits in cabbage (0.5 mg/kg for acetamiprid and 2 mg/kg for pyridaben) in China. The chronic and acute risk values of acetamiprid and pyridaben were 0.0787-33.3%, implying acceptable health hazards to Chinese consumers. In conclusion, applying 50% WP in cabbage fields under Good Agricultural Practices is acceptable. These results provide essential data for using mixtures of acetamiprid and pyridaben in cabbage fields.

Simultaneous determination of residues of multiple pesticides and their metabolites in citrus and orange juice from markets in China: residue levels and dietary risk assessment.

Consumers are becoming more concerned about pesticide residues in food. Since citrus represent a significant portion of the diet, it is appropriate to monitor the pesticide residues in citrus. In this paper, we modified a QuEChERS method combined with HPLC-MS/MS to investigate residue levels of 15 pesticides and 3 metabolites in citrus (whole fruit and pulp) and orange juice from the markets in China. And the dietary exposure risks were evaluated by using the hazard quotient (HQ) and hazard index (HI) methods based on deterministic and probabilistic models. The recoveries of the modified method ranged from 70 to 112% at three spike levels of 0.005-0.5 mg/kg with relative standard deviations of 1.0-18.1%. Pesticide residues were detected in 85.84% of the whole citrus and 40.00% of pulp, with concentrations ranging from 0.005 to 0.47 mg/kg, which did not exceed their maximum residue limits (MRLs) in China. The HQ (0.01-11.41%) and HI (0.07-16.2%) were both less than 100%, demonstrating that chronic, acute, and cumulative dietary risks were acceptable. Notably, the risk for children (1-6 years old, 1.96-16.2%) was higher than that for the general population (0.76-6.25%). The results of our study can provide a valuable reference for regular monitoring to protect public health and ensure pesticide management.

Dissipation patterns, residue analysis, and risk evaluation of hexaflumuron in turnip and cauliflower under Chinese growth conditions.

Hexaflumuron has been globally registered over 2 decades to control the pests in brassicaceous vegetables, while data on its dissipation and residues in turnip and cauliflower is scarce. Herein, field trials were carried out at six representative experimental sites to study the dissipation behaviors and terminal residues of hexaflumuron in turnip and cauliflower. The residual amounts of hexaflumuron were extracted using a modified QuEChERS and analyzed with liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), the chronic dietary risk to Chinese populations was evaluated, and the maximum residue limit (MRL) in cauliflower, turnip tubers, and turnip leaves was calculated by the OECD MRL calculator. The single first-order kinetics model was the best-fitted kinetics model for hexaflumuron dissipation in cauliflower. The indeterminate order rate equation and first-order multi-compartment kinetic model were the best formulae for hexaflumuron dissipation in turnip leaves. The half-lives of hexaflumuron ranged from 0.686 to 1.35 and 2.41 to 6.71 days in cauliflower and turnip leaves, respectively. The terminal residues of hexaflumuron in turnip leaves of 0.321-9.59 mg/kg were much higher than in turnip tubers of < 0.01-0.708 mg/kg and cauliflower of < 0.01-1.49 mg/kg at sampling intervals of 0, 5, 7, and 10 days. The chronic dietary risk of hexaflumuron in the preharvest interval of 7 days was lower than 100% and much higher than 0.01%, indicating acceptable but nonnegligible health hazards for Chinese consumers. Therefore, MRL values of hexaflumuron were proposed as 2, 0.8, and 10 mg/kg in cauliflower, turnip tubers, and turnip leaves, respectively.

Photodegradation of the Fungicide Isopyrazam in Aqueous Solution: Kinetics, Photolytic Pathways, and Aquatic Toxicity.

Photodegradation behavior of a new fungicide isopyrazam in water under simulated sunlight and ultraviolet (UV) irradiation was studied. The photolysis half-life (t1/2) of isopyrazam in purified water was 195 h under simulated sunlight, which was decreased to 46-88 h, 28-51 h, and 13-18 h in the presence of NO3-, Fe3+, and riboflavin, respectively. UV irradiation accelerated the photolysis of isopyrazam with a half-life of 30 min and revealed varied degradation rates in acidic (0.011 min-1), neutral (0.024 min-1), and alkaline solutions (0.022 min-1). Nine transformation products under simulated sunlight and UV were found, and photolytic pathways were proposed to include cleavage of C-N bonds, hydroxylation, nitration, demethylation, dehydrofluorination, and photoisomerization. The acute toxicity of defluorinated isopyrazam (TP 4) and the chronic toxicity of isomerized isopyrazam (TP 9) to aquatic organisms were approximately twice that of isopyrazam. These findings provide insights into environmental risk assessment and management of water pollution.

Dissipation, residue distribution, and risk assessment of ethiprole and its metabolites in rice under various open field conditions.

BACKGROUND: Ethiprole has been registered to control planthoppers in rice fields for many years in Asia. However, its dissipation and residues in rice under natural field conditions and health hazards are largely unclear. In the present study, a modified QuEChERS (i.e. Quick Easy Cheap Effective Rugged Safe) and high-performance liquid chromatography-tandem mass spectrometry method was established to detect ethiprole and its metabolites, ethiprole amide and ethiprole sulfone, in brown rice, rice husks, and rice straw. The field experiments were implemented in 12 representative provinces of China under Good Agricultural Practices aiming to investigate the fate and terminal residues of ethiprole and its metabolites in rice. Finally, the dietary risk of ethiprole was evaluated. RESULTS: The average recoveries of these analytes in all matrices were 86.4-99.0% with a repeatability of 0.575-9.38%. The limits of quantification for each compound were 0.01 mg kg-1 . Dissipation of ethiprole followed the single first-order, first + first-order, and first-order multi-compartment kinetic models with a half-life of 2.68-8.99 days in rice husks. The dissipation half-life of ethiprole combining all metabolites was 5.20-16.2 days in rice husks. The terminal residues of ethiprole and its metabolites at preharvest intervals of 21 days were < 0.011, 0.25, and 0.20 mg kg-1 in brown rice, rice husks, and rice straw, respectively. Ethiprole amide was undetectable in all matrices, and the risk quotient of ethiprole was far less than 100%. CONCLUSION: Ethiprole rapidly converted to ethiprole sulfone in rice, and ethiprole and ethiprole sulfone mainly remained in rice husks and straws. The dietary risk of ethiprole was acceptable for Chinese consumers. © 2023 Society of Chemical Industry.

Residue levels of emamectin benzoate, imidacloprid and its major metabolites in cabbage from 12 regions in China and dietary risk assessment.

A modified quick, easy, cheap, effective, rugged and safe method combined with high-performance liquid chromatography-tandem mass spectrometry was established to investigate the residues of emamectin benzoate (EB), imidacloprid (IMI) and five IMI metabolites (IMI-olefin, IMI-urea, IMI-guanidine, 5-OH and 6-CNA) in cabbage. The average recoveries of the seven compounds in cabbage were 80-102%, with relative standard deviations < 8.0%. The limit of quantification for each compound was 0.01 mg kg-1 . Standardized residue tests were carried out in 12 areas of China under Good Agricultural Practice conditions. A 10% EB-IMI microcapsule suspension was applied once with the high recommended dosage (18 g a.i. ha-1 ) on cabbage. The residues of EB (<0.01 mg kg-1 ), IMI (<0.016 mg kg-1 ) and the sum of IMI and its metabolites (<0.068 mg kg-1 ) in cabbage with the recommended preharvest interval (7 days) were lower than the maximum residue limits in China. Based on residual data from fields, toxicology data and Chinese dietary patterns, dietary risk assessments were conducted. Both the chronic risk quotients (25.2-73.1%) and acute risk quotients (0.43-1.57%) of EB and IMI were below 100%, indicating no unacceptable public health risk for different populations. This study provides guidance on the rational application of these insecticides in cabbage.

Residue levels and dietary risk evaluation of prothioconazole-desthio and kresoxim-methyl in cucumbers after field application in twelve regions in China.

A commercial formulation called prothioconazole·kresoxim-methyl 50% water dispersible granule (WG), used to control the powdery mildew, is under registration for use on cucumbers. Therefore it is urgent to validate the reliability of the recommended good agricultural practices (GAP) conditions (187.5 g a.i. ha-1, three sprays with a 7-d interval, and a pre-harvest interval of 3 d) by conducting field trials in 12 regions in China, as required by national regulations, with a subsequent risk assessment. The residues of prothioconazole-desthio and kresoxim-methyl in field samples were determined using QuEChERS coupled with high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS). On the suggested pre-harvest interval (PHI, 3 d), the residual concentrations of prothioconazole-desthio (no maximum residue limit set in China) and kresoxim-methyl (maximum residue limit = 0.5 mg/kg) in cucumbers were 0.01-0.020 and 0.01-0.050 mg/kg, respectively. The acute risk quotients of prothioconazole-desthio in cucumbers were no higher than 0.079% for Chinese consumers. The chronic dietary risk quotient of kresoxim-methyl and of prothioconazole-desthio for different groups of consumers in China ranged from 2.3% to 5.3% and from 1.6% to 4.6%, respectively. Thus, prothioconazole·kresoxim-methyl 50% WG sprayed on cucumbers under the recommended GAP information can pose a negligible risk for Chinese consumers.

Residue analysis and dietary risk assessment of thiamethoxam, flonicamid and their metabolites in cucumber under field conditions in China.

Thiamethoxam and flonicamid are two representative insecticides of neonicotinoids which are used to treat cucumber aphids, causing food safety and human health problems. A 60% thiamethoxam-flonicamid commercial mixture water dispersible granule (WDG) is being prepared for registering in China, so it is essential to investigate the residue levels of these neonicotinoids and their metabolites in cucumber and evaluate the dietary risks of these insecticides. We developed a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of thiamethoxam and its metabolite clothianidin, flonicamid and its metabolites 4-trifluoromethylnicotinic acid (TFNA), 4-trifluoromethilnicotinamide (TFNA-AM), 4-(trifluoromethyl) nicotinol glycine (TFNG) in cucumber. Method validation indicated good selectivity, linearity (r ≥ 0.9996), accuracy (recoveries of 80-101%), precision (relative standard deviations (RSD) ≤ 9.1%), sensitivity (limits of detection (LOD), 0.28-1.44 × 10-3 mg/L; limits of quantification (LOQ), 0.01 mg/kg) and minor matrix effect (ME) ( ≤|± 5%|). In the terminal residue trials under good agricultural practice (GAP) conditions, the residue levels of six analytes in cucumber samples were ˂0.01-0.215 mg/kg after application trice with an interval of 7 days based on pre-harvest interval (PHI) of 3 days under the high recommended dosage of 54 g active ingredient/ha (g a.i./ha). Relevant toxicological, residual chemistry parameters and dietary consumption of the residents were applied to assess the potential risk of dietary exposure. The chronic and acute dietary exposure assessment risk quotient (RQ) values were less than 1. The above results indicated that the potential dietary intake risk of this formulation was negligible to consumers.

Residue levels and dietary risk assessment of fluopimomide, pyraclostrobin and its metabolite BF-500-3 in garlic ecosystems under field conditions.

To evaluate the residue levels of fluopimomide, pyraclostrobin and its metabolite BF-500-3 in garlic ecosystems, supervised garlic field trials with a commercial formulation (pyraclostrobin·fluopimomide 30% suspension concentrate (SC)) were conducted in six regions of China according to the Good Agricultural Practices (GAP). The residues of fluopimomide, pyraclostrobin and BF-500-3 in field samples were determined using a QuEChERS method combined with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The average recoveries of all target compounds were 76-94% with relative standard deviations (RSDs) of 1.0-14.5% and limits of quantitation (LOQs) of 0.002 mg/kg. At the recommended pre-harvest interval (PHI, 10 days), the residues of fluopimomide, pyraclostrobin and BF-500-3 were below 0.16, 0.77 and 0.12 mg/kg in garlic chive; below 0.027, 0.22 and 0.002 mg/kg in garlic scape; and below 0.002, 0.002 and 0.002 mg/kg in garlic, respectively. Dietary intake risks were calculated using risk quotients (RQs) based on field residual data, toxicological data and dietary patterns. The chronic dietary risk quotients (RQc) of pyraclostrobin and fluopimomide were 48.42% and 0.36%, respectively. The acute dietary risk quotients (RQa) of pyraclostrobin in garlic were 0.06-0.15%. These results indicated a low dietary risk for consumers. This study could provide scientific guidance for the application of pyraclostrobin and fluopimomide in garlic.

Fate and dietary risk assessment of pyriproxyfen, dinotefuran, and its metabolites residues in tomato across different regions in China.

Registration of a new formulation called 30% suspension concentrate (30% SC, pyriproxyfen 10% + dinotefuran 20%) to inhibit the occurrence of whitefly in tomato is currently under review in China, so it is necessary to research the residue behavior and dietary risk of pyriproxyfen and dinotefuran in tomato under field conditions. According to Good Agricultural Practices (GAP), the formulation was sprayed once at the dosage of 112.5 g a.i./ha (active ingredient/hectare) at the initial stage of the occurrence of tomato whitefly and the recommended pre-harvest interval (PHI) for sampling was 5 days. Meanwhile, the residues of pyriproxyfen, dinotefuran, and the metabolites of dinotefuran in tomato samples were determined using QuEChERS (quick, easy, cheap, effective, rugged, and safe) and high-performance liquid chromatography-tandem mass spectrometry. The results showed that the terminal residue levels of the analytes detected in tomato samples were below 0.19 mg/kg for pyriproxyfen and 0.25 mg/kg for dinotefuran at the recommended PHI (5 days), which were lower than the maximum residue limits of China. The dietary risk assessment was also carried out based on field trial results, toxicological data, and Chinese dietary pattern. Both the chronic risk quotients (≤ 26.59%) and acute risk quotients (≤ 1.14%, general population, > 1 year) of pyriproxyfen and dinotefuran were far below 100%, indicating a low risk to consumers' health. The paper will be conducive to provide guidance for the rational application of these insecticides on tomato.

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

Fungicides containing active ingredients of boscalid and pyraclostrobin have been widely applied in watermelon disease control. To provide data for avoiding health hazards caused by fungicides, we investigated its terminal residues and evaluated the dietary risk. In this work, watermelon samples were collected from field sites in six provinces and analyzed with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The average recoveries of boscalid and pyraclostrobin in the watermelon matrix were 97-108% and 93-103%, respectively, with the relative standard deviations (RSDs) ≤ 9.1%. The limits of quantifications (LOQs) were 0.01 and 0.005 mg/kg for boscalid and pyraclostrobin. Twenty-one days after applying the test pesticide with 270 g a.i./ha, the terminal residues of boscalid and pyraclostrobin were all below 0.05 mg/kg and below the maximum residue limits (MRLs) recommended by European Food Safety Authority (EFSA). According to the national estimated daily intake (NEDI), the risk quotients (RQs) of boscalid and pyraclostrobin were 48.4% and 62.6%, respectively. That indicated the pesticide evaluated in watermelon exhibited a low dietary risk to consumers. All data provide a reference for the MRL establishment of boscalid in watermelon for China.

RPS4XL encoded by lnc-Rps4l inhibits hypoxia-induced pyroptosis by binding HSC70 glycosylation site.

Pyroptosis is involved in pulmonary hypertension (PH); however, whether this process is regulated by long non-coding RNAs (lncRNAs) is unclear. Some lncRNAs encode peptides; therefore, whether the regulation of pyroptosis in PH depends on lncRNAs themselves or their encoded peptides needs to be explored. We aimed to characterize the role of the peptide RPS4XL encoded by lnc-Rps4l and its regulatory mechanisms during pyroptosis in PH. Transgenic mice overexpression of lnc-Rps4l was established to rescue the inhibition of hypoxia-induced pyroptosis in pulmonary artery smooth muscle cells (PASMCs). An adeno-associated virus 9 construct with a mutation in the open reading frame of lnc-Rps4l was used to verify that it could inhibit hypoxia-induced PASMCs pyroptosis through its encoded peptide RPS4XL. Glutathione S-transferase (GST) pull-down assays revealed that RPS4XL bound to HSC70, and microscale thermophoresis (MST) was performed to determine the HSC70 domain that interacted with RPS4XL. Through glycosylation site mutation, we confirmed that RPS4XL inhibited hypoxia-induced PASMCs pyroptosis by regulating HSC70 glycosylation. Our results showed that RPS4XL inhibits pyroptosis in a PH mouse model and hypoxic PASMCs by regulating HSC70 glycosylation. These results further clarify the important mechanism of vascular remodeling in PH pathology.

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 consumed by people, but the pesticide residues on it have received little attention. In this work, field trials were conducted under good agricultural practice conditions to investigate the residues of chlorothalonil, SDS-3701, metalaxyl, and dimethomorph in D. officinale; then the evolution of these pesticides after household processing was studied. The results indicated that chlorothalonil, SDS-3701, metalaxyl, and dimethomorph were 2.41-30.12, 0.20-1.23, 0.07-0.80, and 0.19-7.90 mg kg-1 , respectively, in stems at recommended preharvest interval (30 days). Washing and soaking removed the pesticides in fresh stems with processing factors 0.41-1.14 and 0.12-1.13, respectively. In the brewing test, the transfer rates 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 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.

Estimation of residue levels and dietary risk assessment of cyproconazole and azoxystrobin in cucumber after field application in China.

Residue field trials in cucumber were conducted for the safe use of a commercial formulation of cyproconazole·azoxystrobin 28% suspension concentrate (SC 294 g a.i. ha-1, three applications at a 7-day interval) in the year 2018, in China. To determine the residues of cyproconazole and azoxystrobin in cucumber, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed using high-performance liquid chromatography coupled with tandem mass spectrometry. This validated method was applied to analyze cucumber samples collected from 12 specified regions. At the 3-day interval to harvest, the highest residue (HR) of azoxystrobin was 0.150 mg kg-1, which was lower than the maximum residue limit (MRL; 0.5 mg kg-1) permitted in China, and the HR of cyproconazole was 0.084 mg kg-1, for which no MRL value has been set in China. The chronic risk quotient values of cyproconazole and azoxystrobin for Chinese adults at a 3-day interval to harvest were 2.56% and 13.72%, respectively. The acute risk quotient values of cyproconazole in cucumber were specified as 5.52% for children (1-6 years old) and 2.83% for the adults (> 18 years old) in China. These results indicate that cyproconazole·azoxystrobin 28% SC sprayed on cucumber at the pre-harvest interval of 3 days has no significant potential risk for Chinese consumers.

Residual levels and dietary risk assessment of bifenthrin and dinotefuran and its major metabolites in open wheat field conditions.

To evaluate the residual levels of bifenthrin and dinotefuran, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) and high-performance liquid chromatography-tandem mass spectrometry method for simultaneous detection of bifenthrin and dinotefuran and its major metabolites in wheat was developed and validated. Dietary risk assessments were further performed based on the relevant residual data from 12 wheat fields, toxicology data and dietary patterns. In wheat grain and straw, the recoveries of all analytes ranged from 77 to 102% with the relative standard deviation <9.7% and the limit of quantitation 0.05 mg kg-1 . The highest terminal residue of bifenthrin in wheat grain was 0.069 mg kg-1 and dinotefuran was 0.34 mg kg-1 . Residual concentrations of bifenthrin and dinotefuran decreased to <0.05 and 0.15 mg kg-1 at 21 days (pre-harvest interval), respectively. The chronic risk quotient ranged from 6.4 to 62.7% and the acute risk quotient varied from 0.38 to 17.73%. The chronic and acute dietary risks caused by the terminal residues of the two insecticides were negligible for Chinese populations. The recommended pre-harvest interval was proposed to ensure safe wheat consumption. These data could provide a scientific reference to establish the Chinese maximum residue limit of dinotefuran in wheat.

Residues and Safety Evaluation of Etoxazole, Bifenazate and Its Metabolite Bifenazate-diazene in Citrus Under Open-Field Conditions.

The residues of bifenazate (sum of bifenazate and bifenazate-diazene) and etoxazole in whole citrus and pulp collected from twelve regions of China were monitored and their chronic dietary risk to consumer were also evaluated. The citrus samples were extracted by a QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, and analyzed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The average recoveries of target compounds were ranged from 83 to 100% with relative standard deviations (RSDs) of 0.59-11.8%. The limits of quantification (LOQs) for three analytes were 0.01 mg/kg. At the interval to harvest of 20 and 30 days, the residues of total bifenazate and etoxazole were from below 0.02 to 0.26 mg/kg and from below 0.01 to 0.30 mg/kg in citrus samples. The chronic risk quotients (RQs) were below 100%, indicating no unacceptable risk to consumers.

Evaluation of Dissipation Behavior, Residues, and Dietary Risk Assessment of Fludioxonil in Cherry via QuEChERS Using HPLC-MS/MS Technique.

The chemical fungicide fludioxonil is widely used to control post-harvest fungal disease in cherries. This study was implemented to investigate the dissipation behaviours and residues of fludioxonil on cherries. A reliable and efficient analytical method was established. Cherry samples from four product areas were analyzed by QuEChERS and HPLC-MS/MS methods with acceptable linearity (R2 > 0.99), accuracy (recoveries of 81-94%), and precision (relative standard deviation of 2.5-11.9%). The limits of quantification (LOQs) and limits of detection (LODs) of cherries were 0.01 mg/kg and 0.005 mg/kg. The dissipation of fludioxonil on cherries followed first order kinetics with half-lives of 33.7-44.7 days. The terminal residues of fludioxonil were all lower than 5.00 mg/kg, which is the MRL recommended by the European Commission. According to Chinese dietary patterns and terminal residue distributions, the risk quotient (RQs) of fludioxonil was 0.61%, revealing that the evaluated cherries exhibited an acceptably low dietary risk to consumers.

Residues and dietary intake risk assessments of clomazone, fomesafen, haloxyfop-methyl and its metabolite haloxyfop in spring soybean field ecosystem.

Soybean is an important oilseed crop, but weed can have a significant effect on soybean yield. Clomazone, fomesafen, and haloxyfop-methyl are high-efficacy herbicides, and the combination of these herbicides shows an ideal effect on weed control. However, the residues of these herbicides and their impacts on human health are still largely unknown. In the current study, a rapid, sensitive, and selective method using modified QuECHERS procedure combined with HPLC-MS/MS was established to detect these herbicides in soybean matrices. The limits of quantification were 0.01, 0.01 and 0.025 mg/kg for haloxyfop-methyl, haloxyfop and fomesafen, and 0.005, 0.005 and 0.0125 mg/kg for clomazone in green soybean, soybean grain, and straw, with the average recoveries ranging from 80% to 107%. The terminal residues of the target compounds were all below the corresponding limits of quantification. The dietary risk assessment showed that the risk quotient values were far below the acceptable human consumption levels.