Occurrences of the Typical Agricultural Non-ionic Surfactants Tristyrylphenol Ethoxylates in Cherries ( Cerasus pseudocerasus), Peaches ( Amygdalus persica), and Kiwifruit ( Actinidia chinensis) and the Implications of Human Exposure in China

Dissipation and potential risk of tristyrylphenol ethoxylate homologs in peanuts by spraying and root irrigation: A comparative assessment

Peanuts, known for their nutritional value, health benefits, and delicious taste, are susceptible to agricultural chemical contamination, posing a challenge to the peanut industry in China. While tristyrylphenol ethoxylates (TSPEOs) have garnered attention for their widespread use in pesticide formulations, their dissipation and potential risks in peanuts remain a gap in knowledge. This study, unique in its focus on TSPEOs, investigates their dissipation and potential risks under two common application modes: spraying and root irrigation. The concentration of total TSPEOs in peanut plants was significantly higher when sprayed (435-37,693 μg/kg) than in root irrigation (24-1602 μg/kg). The dissipation of TSPEOs was faster in peanuts and soil when sprayed, with half-lives of 3.67-5.59 d (mean: 4.37 d) and 5.41-7.07 d (mean: 5.95 d), respectively. The residue of TSPEOs in peanut shells and soil were higher with root irrigation (8.9-65.2 and 25.4-305.1 μg/kg, respectively) than with spraying (5.4-30.6 and 8.8-146.5 μg/kg, respectively). These results indicated that the dissipation behavior of TSPEOs in peanuts was influenced by application modes. While the healthy and ecological risk assessments of TSPEOs in soil and peanut shells showed no risks, root irrigation might pose a higher potential risk than spraying. This research provides valuable data for the judicious application of pesticides during peanut cultivation to enhance pesticide utilization and reduce potential risks.

Occurrence and distribution of trisiloxane ethoxylates in citrus orchard soils in China: Analytical challenges

Trisiloxane ethoxylates (TSEOn) are widely used as agricultural surfactants due to their significant synergism with the active ingredients of pesticides, generally, including three typical end groups which are hydroxyl (TSEOn-H), methoxy (TSEOn-CH3), and acetoxy (TSEOn-COCH3), respectively. However, the potential ecotoxicological and endocrine-disrupting risks of TSEOn congeners have recently attracted ever-growing concern. Above all, there is limited research on the concentration levels of TSEOn in agroecosystems. This study, simultaneous analysis of 39 TSEOn oligomers in citrus orchard soils in China was implemented by the modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method detection limits (MDLs) and the method quantification limits (MQLs) for TSEOn were 0.003-0.07 μg/kg and 0.01-0.20 μg/kg, respectively. The recoveries for TSEOn oligomers in soils ranged from 81 % ∼ 106 % with related standard deviations (RSDs) < 7 %. This newly developed UPLC-MS/MS method with high sensitivity and stability allows us to successfully trace the occurrence of TSEOn congeners in the citrus orchard soils from 3 provinces and 1 municipality in China. The detected concentrations of TSEOn-H oligomers in the sampled soils ranged from 0.02 to 0.288 μg/kg (dry weight). The congener profiles of TSEOn-H were dominated by TSEOn-H (n = 6- 8) in the soils. Additionally, the total concentrations of TSEOn-H congeners (ΣTSEOn-H) in the soils were in the range of 0.03 to 1.49 μg/kg. A comparison of ΣTSEOn-H distribution among the different citrus orchard soils indicated a higher level of ΣTSEOn-H in the soil samples collected from Zhejiang Province. Notably, TSEOn-CH3 or TSEOn-COCH3 oligomers were not detected in the tested soils. To the best of our knowledge, this is the first report on the occurrence and distribution of TSEOn congeners in agricultural soils.

The Dissipation Behavior and Risk Assessment of Carbendazim Under Individual and Joint Applications on Peach (Amygdalus persica L.)

Dissipation, residue levels, and ingestion risks of carbendazim in peach (Amygdalus persica L.) were investigated with individual and joint applications in the present study. The dissipation kinetics of carbendazim, chlorpyrifos, prochloraz, and imidacloprid were evaluated by the first-order kinetics. When carbendazim was individually applied, the final residual concentration was 2.97 mg kg-1 and the half-life was 17.4 d. In the joint application of carbendazim with chlorpyrifos, prochloraz, and imidacloprid, the residual concentrations at 35 d after spraying were 7.16, 7.50, and 4.26 mg kg-1 and the half-lives were 30.8, 23.7, and 23.2 d, respectively, which showed an increase of 1.3-1.8 times compared with the single application of carbendazim. In addition, the effects of household processing of rinsing and peeling were investigated, and a high removal rate of 54.6% and 76.5% were found. Furthermore, the carbendazim ingestion risk assessment was conducted, which indicated that the acute health risk (aHI) and hazard quotient (HQ) of carbendazim were all within acceptable levels ranging from 21.7% to 40.9%. However, a higher ingestion risk of carbendazim was found under the joint application. This study provides some preliminary guidance for the joint application and risk assessment of carbendazim in peach, which is worth further investigation.

Different dissipation potential and dietary risk assessment of tristyrylphenol ethoxylates in cowpea ecosystem in China

Tristyrylphenol ethoxylates (TSPEOn) are widely used as inert ingredients in pesticide formulations in the world. However, the information on the dissipation behavior of different homologs TSPEOn in agro-products is lacking. To investigate the dissipation behavior of TSPEOn, a cowpea field experiment treated with TSPEOn at different doses was carried out in Guangdong province, China. Different 24 TSPEO homologs were all detected in cowpea from the field terminal residue experiments, and the total concentrations of TSPEO homologs in cowpea were 40.0–1,374 μg/kg. The dissipation half-lives of 24 TSPEO homologs in soil were 1.51–2.35 times longer than those in cowpea. The long-chain homologs TSPEOn were dissipated faster than the short-chain homologs TSPEOn, suggesting a homolog-specific degradation of the TSPEOn in the cowpea ecosystem. The characteristic bimodal profiles of TSPEOn (n = 6–29) differing from that of the commercial TSPEOn were observed in the cowpea terminal residues experiment, indicating that the long-chain TSPEOn would degrade to short-chain TSPEOn in cowpea and soil. The acute and chronic dietary exposure risks of ΣTSPEOn in cowpea are within acceptable margins for human consumption across different ages and genders. But the health risks to children should be noticed in future.

Impact of pesticide formulation excipients and employed analytical approach on relative matrix effects of pesticide determination in strawberries

Relative matrix effects between an ambient mass spectrometric technique known as coated blade spray (CBS) and liquid chromatographic separation approach when applied to multiresidue pesticide analysis in strawberry samples are explored. Acceptable slope relative standard deviations (RSD <15 %) were observed for the 9 compounds under study for both CBS-MS/MS (2.2-12.6 %) and LC-MS/MS (2.8-12.9 %) approaches. The findings signify both the elimination of relative matrix effects with the sample preparation and matrix match calibration with internal standard correction methods employed along with no matrix effect compromise made when using the direct-to-MS approach. Similarly, slopes of pesticides spiked from commercially available formulations (containing one or two pesticides) were found to not differ significantly from slopes generated with multiresidue pesticide standards (containing 24 additional pesticides besides the target 9 analytes) with either technique, highlighting the resistance of the employed methods to the excipients present in pesticide formulations in large amounts.

Dissipation and risk assessment of forchlorfenuron and its major metabolites in oriental melon under greenhouse cultivation

Forchlorfenuron is a widely used plant growth regulator. The uptake of forchlorfenuron and its major metabolites poses a potential risk for human health. However, little is known about the dissipation of forchlorfenuron and its major metabolites in agricultural food. In this study, the metabolite 4-hydroxyphenyl-forchlorfenuron was first identified in oriental melon, which exhibited the highest level of residues of 4.42-5.12 μg/kg on the 4-7th days after application. Forchlorfenuron was found to be dissipated rapidly in melon at the recommended application rates, with half-lives ranging from 1.20 to 1.33 days. The rate of dissipation of 4-hydroxyphenyl-forchlorfenuron was greater than that of metabolism from forchlorfenuron in the oriental melon. However, the other metabolite, 3-hydroxyphenyl-forchlorfenuron, was not detected in oriental melon. The risk assessment showed that the acute and chronic dietary exposure risks of forchlorfenuron in oriental melon were 0.0011-0.0037% and 0.06-0.12%, respectively, suggesting little health risk to Chinese consumers.

The degradation and metabolism of chlorfluazuron and flonicamid in tea: A risk assessment from tea garden to cup

Degradation and metabolism of chlorfluazuron and flonicamid from tea garden to cup were simultaneously investigated by a modified QuEChERS method coupled with UPLC-MS/MS quantification. The dissipation half-lives of chlorfluazuron, flonicamid, and total flonicamid (the sum of flonicamid and its metabolites TFNG, TFNA, and TFNA-AM) in fresh tea leaves during tea growth were 6.0 d, 4.8 d, and 8.1 d, respectively. TFNG and TFNA were generated during tea growth. After tea processing, the residues of chlorfluazuron, flonicamid, and its metabolites in black tea were higher than those in green tea. The average processing factors of chlorfluazuron, flonicamid, and total flonicamid in black tea were 2.54, 3.02, and 2.87, respectively, while in green tea they were 2.40, 2.93, and 2.79, respectively. TFNG, TFNA, and TFNA-AM were formed rapidly during the drying step. Considering the influence of water content at various processing steps, the average loss rates of chlorfluazuron, flonicamid, and total flonicamid residue from fresh tea leaves to black tea were 16.7%, 33.8%, and 20.7%, respectively, and 29.6%, 14.0% and 18.2%, respectively, in the case of green tea. The highest leaching rates of chlorfluazuron, flonicamid, and total flonicamid during tea brewing were 6.8%, 97.0%, and 97.4%, respectively, in black tea infusion, and 6.0%, 98.9%, and 98.6%, respectively, in green tea infusion. The metabolites, especially TFNG, had a higher leaching rate during tea brewing. The migration of chlorfluazuron from fresh leaves to tea infusion was low, and the migration of flonicamid was high. The RQc and RQa of chlorfluazuron and total flonicamid were less than 1. This result indicates that the potential dietary intake risk of chlorfluazuron from tea is negligible. However, the risk of total flonicamid intake is three times higher than that of chlorfluazuron. There is a potential risk of intake of flonicamid and its metabolites in tea for human consumption.

Occurrences of eight common-used pesticide adjuvants in ten vegetable species and implications for dietary intake in North China

Pesticide adjuvants (PAs) are important components of pesticide products. However, limited information is available regarding their occurrences in foodstuffs. Herein, eight common-used PAs were investigated in vegetables in North China in 2014-2016. The residue levels of total PAs in vegetables from markets and farms were 500 and 661 μg/kg, respectively. The highest residues of total PAs were found in cauliflowers (average: 1.53 × 10³ μg/kg, market vegetables) and spinaches (average: 3.72 × 10³ μg/kg, farm vegetables), respectively. In addition, Tristyrylphenol ethoxylates (TPE) dominated the total 8 PAs concentrations in most vegetable species. Moreover, the risk assessment showed that the human health risks associated with TPE and nonylphenol (NP) exposure via vegetables for adults were acceptable, and the estimated daily intakes (EDIs) of other six PAs were in the range of <0.010-0.89 μg/kg bw/day, which were less likely to pose a threat to human health.

Dissipation and dietary risk assessment of tristyrylphenol ethoxylate homologues in cucumber after field application

The potential for tristyrylphenol ethoxylates (TSPEOs) residues to contaminate crops or be released into the environment is of increasing concern, as they are toxic to living organisms. This study determined the dissipation of TSPEO homologues in cucumber under field conditions. TSPEOn (n = 6-29) dissipated more rapidly in cucumber than in soil samples, with half-lives of 1.80-4.30 d and 3.73-6.52 d, respectively. Short-chain TSPEOn (n = 6-11) persisted for longer than other oligomers in soil. Concentrations of the final residues (∑TSPEOs) in cucumber and soil were 24.3-1349 μg/kg and 47.3-1337 μg/kg, respectively. TSP15EO or TSP16EO was the dominant oligomer, with concentrations of 2.30-150 μg/kg. The risk assessment showed that the acute and chronic dietary exposure risks of ∑TSPEOs in cucumber were 0.03-0.57% and 0.05-0.39%, respectively, suggesting little or no health risk to Chinese consumers.

How does substrate hydrophobicity affect the morphological features of reconstituted wax films and their interactions with nonionic surfactant and pesticide?

HYPOTHESIS

Surfactants are widely used in agri-sprays to improve pesticide efficiency, but the mechanism underlying their interactions with the surface wax film on plants remains poorly understood. To facilitate physical characterisations, we have reconstituted wheat cuticular wax films onto an optically flat silicon substrate with and without octadecyltrimethoxysilane modification to control surface hydrophobicity.

EXPERIMENTS

Imaging techniques including scanning electron microscopy (SEM) unravelled morphological features of the reconstituted wax films similar to those on leaves, showing little impact from the different substrates used. Neutron reflection (NR) established that reconstituted wax films were comprised of an underlying wax film decorated with top surface wax protrusions, a common feature irrespective of substrate hydrophobicity and highly consistent with what was observed from natural wax films. NR measurements, with the help of isotopic H/D substitutions to modify the scattering contributions of the wax and solvent, revealed different wax regimes within the wax films, illustrating the impact of surface hydrophilicity on the nanostructures within the wax films.

FINDINGS

It was observed from both spectroscopic ellipsometry and NR measurements that wax films formed on the hydrophobic substrate were more robust and durable against attack by nonionic surfactant C₁₂E₆ solubilised with pesticide Cyprodinil (CP) than films coated on the bare hydrophilic silica. Thus, the former could be a more feasible model for studying the wax-surfactant-pesticide interactions.

Dissipation Profiles of Tristyrylphenol Ethoxylate Homologs in Lettuce under Greenhouse and Field Conditions

Tristyrylphenol ethoxylates (TSPEOs) have been increasingly used in pesticide formulations as inert ingredients in China, but little information exists on the dissipation behavior of TSPEOs in foodstuffs. In this work, a rapid method for measuring TSPEO homologs in lettuce using QuEChERS and HPLC-MS/MS was established. This method was used to study the dissipation and distribution profiles of TSPEOs in lettuce. TSPEO homologs degraded rapidly under greenhouse and field conditions, with half-lives of 2.18-5.39 and 1.82-5.52 days, respectively. TSPEOn (n = 6-9) were relatively persistent in the field. The distribution profiles showed an obvious difference between the two conditions. TSPEOn (n = 14-18) degraded to shorter-chain TSPEOs with time, and a two-peak (TSP16EO and TSP10EO) homolog distribution profile occurred between 7 and 14 days of treatment under greenhouse conditions. This work improves the understanding of the dissipation behavior of TSPEO homologs in lettuce.