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

Improved analysis of 230 pesticide residues in three fermented soy products by using automated one-step accelerated solvent extraction coupled with GC-MS/MS

Consumer concerns over healthy diets are increasing as a result of the toxicity and persistence of pesticide residues in foodstuffs. Developing sensitive and high-throughput monitoring techniques for these trace residues is seen as an essential step in ensuring food safety. An automatic and sensitive multi-residue analytical method was developed and validated for the simultaneous determination of 230 compounds, including pesticides and their hazardous metabolites, in fermented soy products. The method included preparing the sample using on-line extraction and clean-up system based on accelerated solvent extraction (ASE), then determining the analytes using GC-MS/MS techniques. The homogenized samples (soy sauce, douchi, and sufu) were automatically extracted at 80 °C and 10.3 MPa and at the same time, in situ cleaned by 300 mg of primary secondary amine (PSA) combined with 20 mg of hydroxylated multi-walled carbon nanotubes in an extraction cell. The method obtained excellent calibration linearity (r > 0.9220) and a satisfactory analysis of the targeted compounds, which were evaluated with matrix-matched calibration standards over the range of 5-500 μg L-1. The limit of detections (LODs) of analytes were in the range of 0.01-1.29 μg kg-1, 0.01-1.39 μg kg-1, and 0.01-1.34 μg kg-1 in soy sauce, douchi, and sufu, respectively. The limit of quantifications (LOQs), which defined as the lowest spiking level, were set at 5.0 μg kg-1. The recoveries were within 70-120 % for over 95 % of the analytes, and the relative standard deviations (RSDs) were below 13.6 %. Moreover, a positive detection rate of 47 % were obtained when the proposed method was used on 15 real fermented soy products. These results suggested that the developed high-throughput method is highly feasible for monitoring of these target analytes in trace level.

Spatial distribution and ecological-health risks associated with herbicides in soils and crop kernels of the black soil region in China

Herbicides are vital inputs for food production; however, their associated risks and hazards are pressing concerns. In black soil, the cumulative toxic effects of compound herbicides and potential risks to humans are not yet fully understood. Thus, this study conducted a comprehensive investigation to assess herbicide residue characteristics and the associated ecological health risks in representative black soil regions where major food crops (maize, soybean, and rice) are cultivated. Findings revealed that the soil harbored a collective presence of 29 herbicides, exhibiting total concentrations ranging from 111.92 to 996.14 μg/kg dry weight (dw). This can be attributed to the extensive use of herbicides over the years and their long half-lives, which results in the accumulation of multiple herbicide residues in the soil. Similarly, the total herbicide levels in maize, soybean, and rice kernels were 1173-61,564, 1721-9342, and 3775-8094 ng/kg dw, respectively. Multiple herbicide residues at all monitored sites were attributed to continuous crop barriers in soybean fields and the adoption of soybean and maize crop rotations. Notably, herbicides pose ecological risks in the black soil region, exhibiting high-risk levels of 79 %, 24 %, and 14 % at the sites monitored for oxyfluorfen, clomazone, and butachlor, respectively. Carcinogenic atrazine exhibited low- and medium-risk levels in 34 % and 63 % of soil samples, respectively. These results can serve as a scientific basis for establishing herbicide residue thresholds in agricultural soils within black soil areas and for implementing effective control measures to prevent herbicide contamination in agricultural ecosystems.

Remediation of fomesafen contaminated soil by Bacillus sp. Za: Degradation pathway, community structure and bioenhanced remediation

Fomesafen is a diphenyl ether herbicide used to control the growth of broadleaf weeds in bean fields. The persistence, phytotoxicity, and negative impact on crop rotation associated with this herbicide have led to an increasing concern about the buildup of fomesafen residues in agricultural soils. The exigent matter of treatment and remediation of soils contaminated with fomesafen has surfaced. Nevertheless, the degradation pathway of fomesafen in soil remains nebulous. In this study, Bacillus sp. Za was utilized to degrade fomesafen residues in black and yellow brown soils. Fomesafen's degradation rate by strain Za in black soil reached 74.4%, and in yellow brown soil was 69.2% within 30 days. Twelve intermediate metabolites of fomesafen were identified in different soils, with nine metabolites present in black soil and eight found in yellow brown soil. Subsequently, the degradation pathway of fomesafen within these two soils was inferred. The dynamic change process of soil bacterial community structure in the degradation of fomesafen by strain Za was analyzed. The results showed that strain Za potentially facilitate the restoration of bacterial community diversity and richness in soil samples treated with fomesafen, and there were significant differences in species composition at phylum and genus levels between these two soils. However, both soils shared a dominant phylum and genus, Actinobacteriota, Proteoobacteria, Firmicutes and Chloroflexi dominated in two soils, with a high relative abundance of Sphingomonas and Bacillus. Moreover, an intermediate metabolite acetaminophen degrading bacterium, designated as Pseudomonas sp. YXA-1, was isolated from yellow brown soil. When strain YXA-1 was employed in tandem with strain Za to remediate fomesafen contaminated soil, the degradation rate of fomesafen markedly increased. Overall, this study furnishes crucial insights into the degradation pathway of fomesafen in soil, and presents bacterial strain resources potentially beneficial for soil remediation in circumstances of fomesafen contamination.

A nitroreductase DnrA catalyzes the biotransformation of several diphenyl ether herbicides in Bacillus sp. Za

Diphenyl ether herbicides, typical globally used herbicides, threaten the agricultural environment and the sensitive crops. The microbial degradation pathways of diphenyl ether herbicides are well studied, but the nitroreduction of diphenyl ether herbicides by purified enzymes is still unclear. Here, the gene dnrA, encoding a nitroreductase DnrA responsible for the reduction of nitro to amino groups, was identified from the strain Bacillus sp. Za. DnrA had a broad substrate spectrum, and the K_m values of DnrA for different diphenyl ether herbicides were 20.67 μM (fomesafen), 23.64 μM (bifenox), 26.19 μM (fluoroglycofen), 28.24 μM (acifluorfen), and 36.32 μM (lactofen). DnrA also mitigated the growth inhibition effect on cucumber and sorghum through nitroreduction. Molecular docking revealed the mechanisms of the compounds fomesafen, bifenox, fluoroglycofen, lactofen, and acifluorfen with DnrA. Fomesafen showed higher affinities and lower binding energy values for DnrA, and residue Arg244 affected the affinity between diphenyl ether herbicides and DnrA. This research provides new genetic resources and insights into the microbial remediation of diphenyl ether herbicide-contaminated environments. KEY POINTS: • Nitroreductase DnrA transforms the nitro group of diphenyl ether herbicides. • Nitroreductase DnrA reduces the toxicity of diphenyl ether herbicides. • The distance between Arg244 and the herbicides is related to catalytic efficiency.

Perfluoroalkyl Group-Covered Organosilica Films for the Sensitive Detection of Sulfonylurea Herbicides in Laser Desorption/Ionization Mass Spectrometry

Simple and rapid screening of agrochemicals greatly contributes to food and environmental safety. Matrix-free laser desorption/ionization mass spectrometry (LDI-MS) is an effective tool for high-throughput analysis of low-molecular-weight compounds. In this study, we report a UV-laser-absorbing organosilica film for the sensitive detection of various sulfonylurea herbicides using LDI-MS. Organosilica films with fluoroalkyl groups on the organic part are fabricated, followed by additional modification of the silica moiety with a fluoroalkyl coupling agent to cover the film surface with hydrophobic fluoroalkyl groups. Nanoimprinting is conducted to impart nanostructures on the film surface to enhance the LDI performance. The fabricated nanostructured organosilica films accomplish sensitive detection of cyclosulfamuron and azimsulfuron at concentrations as low as 1 fmol μL^-1. The applicability of the nanostructured organosilica films is confirmed by the recovery of cyclosulfamuron and ethametsulfuron-methyl from pea sprouts (Pisum sativum) hydroponically grown in herbicide-spiked water at concentrations of 0.5 ppm.

Target gene mutation and enhanced metabolism confer fomesafen resistance in an Amaranthus retroflexus L. population from China

Amaranthus retroflexus L., a troublesome annual dicotyledonous weed species, is highly competitive with soybean (Glycine max L.). A single-dose herbicide-resistance screening assay identified an A. retroflexus population with suspected resistance to fomesafen. Whole-plant dose-response assays demonstrated that the resistant population (2492) was resistant to protoporphyrinogen oxidase (PPO)-inhibiting herbicides (50.6-fold fomesafen resistance and > 8.1-fold lactofen resistance) compared to a susceptible (S) population. PPX2 gene sequence analysis showed an Arg₁₂₈Gly amino acid substitution in the 2492 population. Moreover, pretreatment of malathion and the fomesafen metabolic assays through HPLC-MS demonstrated enhanced fomesafen metabolism in the 2492 population. Additionally, the 2492 population was 10.4-fold more resistant to the ALS-inhibiting herbicide imazethapyr and 16.8-fold more resistant to thifensulfuron-methyl than the S population. ALS gene sequence analysis showed an Ala₂₀₅Val amino acid substitution in the 2492 population. This population of A. retroflexus has coexisting target-site resistance and non-target-site mechanisms for resistance to fomesafen. Multiple herbicide resistance may mean it is necessary to adjust weed management strategies to better control the resistant population.

Dissipation and Distribution of Prochloraz in Bananas and a Risk Assessment of Its Dietary Intake

BACKGROUND

As a systematic fungicide, prochloraz is often used to control banana freckle disease, and it is significant to assess the safety and risk of prochloraz.

METHODS

The dissipation kinetics and distribution of prochloraz in bananas were measured by high-performance liquid chromatography (HPLC).

RESULTS

The results showed that the fortified recoveries in bananas were 83.01-99.12%, and the relative standard deviations (RSDs) were 2.45-7.84%. The half-life of prochloraz in banana peel (3.93-5.60 d) was significantly lower than it was in whole banana (8.25-10.80 d) and banana pulp (10.35-12.84 d). The terminal residue of prochloraz in banana fruits was below the maximum residue level (MRL, China) at pre-harvest intervals (PHI) of 21 d. Moreover, the residue of prochloraz in banana peel was always 1.06-7.71 times greater than it was in banana pulp. The dietary risk assessment results indicated that the prochloraz residue in bananas at PHI of 21 d was safe for representative populations. (4) Conclusions: We found that a 26.7% prochloraz emulsion oil in water (EW) diluted 1000-fold and sprayed three times under field conditions was safe and reliable, providing a reference for the safe application of prochloraz in bananas.

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.

Ethanol-ammonium sulfate system based modified quick, easy, cheap, effective, rugged and safe method for the determination of four neonicotinoid pesticide and metabolite residues in two canned fruits

As the pesticide and its metabolite residues in processed fruits could become a significant route of human exposure. The work presented herein focuses on developing a feasible quick, easy, cheap, effective, rugged and safe method with improved extraction and cleanup system for the determination of imidacloprid, acetamiprid, thiamethoxam and clothianidin (metabolite of thiamethoxam) in canned fruits. The low toxic solvent ethanol was used to extract the analytes, and ammonium sulfate was used to promote the phase separation. Moreover, the carboxylated multi walled carbon nanotube was acted as the clean-up sorbent for removal of high solubility impurities. The proposed method was validated with fortified real samples at different concentration levels (20∼200 μg kg^-1 ). Recoveries obtained from three spiked levels (20, 50, 200 μg kg^-1 ) were ranged from 74.9% to 86.4% with relative standard deviations of the intra-day and inter-day in the range of 0.8 to 5.5% and 2.0 to 7.1%, respectively. Limit of detections were ranged from 0.2 to 0.5 μg kg^-1 and 0.2 to 0.6 μg kg^-1 for orange and peach, respectively. The results demonstrated that the proposed method could be considered appropriate, comparatively lower toxic for the analysis of neonicotinoid pesticide residues in canned fruit. This article is protected by copyright. All rights reserved.

Dissipation behaviour, residue analysis, and dietary safety evaluation of chlorfenapyr on various vegetables in China

Chlorfenapyr has been widely used in recent years to control a variety of pests on fruit and vegetables. Cabbage, leek, asparagus, and chive are four of the most common green foods consumed word wide; their pesticide residue issues have also received more attention. Therefore, studies on the residue analysis, degradation evaluation and dietary risk assessment based on the complete residue definition of chlorfenapyr on these four vegetables were essential and urgently needed. A reliable analytical method was developed and applied to simultaneously determine the content of chlorfenapyr and its metabolite tralopyril residues on the four vegetables. Recoveries were satisfactory (84%-110% for chlorfenapyr; 83%-106% for tralopyril) at a spiked level of 0.01-1 mg/kg, with intraday precision (n = 5) and interday precision (n = 15) ranging from 1.6% to 8.9% and from 2.4% to 9.1%, respectively. The limits of quantification (LOQs) were all 0.01 mg/kg. On the basis of supervised field trials, the degradation half-lives of chlorfenapyr were 1.2-9.8 days. Chlorfenapyr rapidly degraded on asparagus, but persisted much longer on chive. The terminal concentration of chlorfenapyr residues varied from <0.01 to 0.84 mg/kg. Additionally, the risk quotients (RQs) ranged from 4.7% to 13.8%, suggesting that chlorfenapyr had a negligible risk for chronic dietary intake of these crops. This study was thus significant in evaluating the degradation rate and quality safety of chlorfenapyr on various vegetables and promoted the development of maximum residue limits.

Phosphate-triggered ratiometric fluoroimmunoassay based on nanobody-alkaline phosphatase fusion for sensitive detection of 1-naphthol for the exposure assessment of pesticide carbaryl

The excessive use of carbaryl has resulted in the risk of its exposure. In this study, we isolated six nanobodies (Nbs) from a camelid phage display library against the biomarker of carbaryl, 1-naphthol (1-NAP). Owing to its characteristics of easy genetic modifications, we produced a nanobody-alkaline phosphatase (Nb-CC4-ALP) fusion protein with good stability. A dual-emission system based ratiometric fluoroimmunoassay (RFIA) for quick and highly sensitive determination of 1-NAP was developed. Silicon nanoparticles (SiNPs) was used as an internal reference and for aggregation-induced emission enhancement (AIEE) of gold nanoclusters (AuNCs), while AuNCs could be quenched by MnO₂ via oxidation. In the presence of ALP, ascorbic acid phosphate (AAP) can be transformed into ascorbic acid (AA), the later can etch MnO₂ to recover the fluorescence of the AuNCs. Based on optimal conditions, the proposed assay showed 220-fold sensitivity improvement in comparison with conventional monoclonal antibody-based ELISA. The recovery test of urine samples and the validation by standard HPLC-FLD demonstrated the proposed assay was an ideal tool for screening 1-NAP and provided technical support for the monitoring of carbaryl exposure.