Molecules

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16 pages, 3434 KiB

Open AccessArticle

The Interaction of Pesticides with Humin Fractions and Their Potential Impact on Non-Extractable Residue Formation

by Aleksandra Ukalska-Jaruga, Romualda Bejger, Bożena Smreczak, Jerzy Weber, Lilla Mielnik, Maria Jerzykiewicz, Irmina Ćwieląg-Piasecka, Elżbieta Jamroz, Magdalena Debicka, Andrzej Kocowicz and Jakub Bekier

Molecules 2023, 28(20), 7146; https://doi.org/10.3390/molecules28207146 - 18 Oct 2023

Cited by 3 | Viewed by 858

Abstract

The constant influx of pesticides into soils is a key environmental issue in terms of their potential retention in the soil, thus reducing their negative impact on the environment. Soil organic matter (SOM) is an important factor influencing the environmental fate of these [...] Read more.

The constant influx of pesticides into soils is a key environmental issue in terms of their potential retention in the soil, thus reducing their negative impact on the environment. Soil organic matter (SOM) is an important factor influencing the environmental fate of these substances. Therefore, the aim of this research was to assess the chemical behavior of pesticides (flufenacet, pendimethalin, α-cypermethrin, metazachlor, acetamiprid) toward stable soil humin fractions (HNs) as a main factor affecting the formation of non-extractable residues of agrochemicals in soil. This research was conducted as a batch experiment according to OECD Guideline 106. For this purpose, HNs were isolated from eight soils with different physicochemical properties (clay content = 16–47%, pH_KCl = 5.6–7.7, TOC = 13.3–49.7 g·kg⁻¹, TN = 1.06–2.90 g·kg⁻¹, TOC/TN = 11.4–13.7) to reflect the various processes of their formation. The extraction was carried out through the sequential separation of humic acids with 0.1 M NaOH, and then the digestion of the remaining mineral fraction with 10% HF/HCl. The pesticide concentrations were detected using GC-MS/MS. The pesticides were characterized based on the different sorption rates to HNs, according to the overall trend: metazachlor (95% of absorbed compound) > acetamiprid (94% of absorbed compound) > cypermethrin (63% of partitioning compound) > flufenacet (39% of partitioning compound) > pendimethalin (28% of partitioning compound). Cypermethrin and metazachlor exhibited the highest saturation dynamic, while the other agrochemicals were much more slowly attracted by the HNs. The obtained sorption kinetic data were congruous to the pseudo-first-order and pseudo-second-order models related to the surface adsorption and interparticle diffusion isotherm. The conducted research showed that the processes of pesticide sorption, apart from physicochemical phenomena, are also affected by the properties of the pollutants themselves (polarity, K_OC) and the soil properties (SOM content, clay content, and pH_KCl). Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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12 pages, 1542 KiB

Open AccessArticle

Impact of Exposure to Pyraclostrobin and to a Pyraclostrobin/Boscalid Mixture on the Mitochondrial Function of Human Hepatocytes

by Mélina Carbone, Barbara Mathieu, Yasmine Vandensande and Bernard Gallez

Molecules 2023, 28(20), 7013; https://doi.org/10.3390/molecules28207013 - 10 Oct 2023

Cited by 2 | Viewed by 1088

Abstract

Fungicides are widely used in agriculture for crop protection. Succinate dehydrogenase inhibitors (SDHIs) and strobilurins inhibit mitochondria electron transport chain (ETC) in fungi, by blocking complex II and complex III, respectively. Questions regarding their selectivity of action for fungi have been raised in [...] Read more.

Fungicides are widely used in agriculture for crop protection. Succinate dehydrogenase inhibitors (SDHIs) and strobilurins inhibit mitochondria electron transport chain (ETC) in fungi, by blocking complex II and complex III, respectively. Questions regarding their selectivity of action for fungi have been raised in the literature, and we previously showed that boscalid and bixafen (SDHIs) alter the mitochondrial function of human hepatocytes. Here, we analyzed the impact of the exposure of human hepatocytes to pyraclostrobin, a fungicide belonging to the class of strobilurins. Using electron paramagnetic resonance (EPR), we observed a decrease in oxygen consumption rate (OCR) and an increase in mitochondrial superoxide levels after 24 h exposure to 0.5 µM concentration. As a consequence, the content in ATP amount in the cells was reduced, the ratio reduced/oxidized glutathione was decreased, and a decrease in cell viability was observed using three different assays (PrestoBlue, crystal violet, and annexin V assays). In addition, as SDHIs and strobilurins are commonly associated in commercial preparations, we evaluated a potential “cocktail” toxic effect. We selected low concentrations of boscalid (0.5 µM) and pyraclostrobin (0.25 µM) that did not induce a mitochondrial dysfunction in liver cells when used separately. In sharp contrast, when both compounds were used in combination at the same concentration, we observed a decrease in OCR, an increase in mitochondrial superoxide production, a decrease in the ratio reduced/oxidized glutathione, and a decrease in cell viability in three different assays. Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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22 pages, 3769 KiB

Open AccessArticle

Soil Organic Matter Composition and pH as Factors Affecting Retention of Carbaryl, Carbofuran and Metolachlor in Soil

by Irmina Ćwieląg-Piasecka

Molecules 2023, 28(14), 5552; https://doi.org/10.3390/molecules28145552 - 20 Jul 2023

Cited by 4 | Viewed by 1202

Abstract

The majority of studies concerning the environmental behavior of hydrophobic pollutants in soil consider soil organic matter (SOM) content as a main factor influencing chemical retention, whereas the composition of SOM and its individual fraction share are often neglected. In the present paper, [...] Read more.

The majority of studies concerning the environmental behavior of hydrophobic pollutants in soil consider soil organic matter (SOM) content as a main factor influencing chemical retention, whereas the composition of SOM and its individual fraction share are often neglected. In the present paper, carbaryl, carbofuran and metolachlor retention by loamy sand and loam topsoil materials is compared and referred to humic acids (CHA) and the residual carbon (CR) content of SOM. Additionally, the sorption-desorption behavior of agrochemicals in soils was tested at a pH of three to seven. Calculated isothermal parameters point to favorable, spontaneous and physical pesticide sorption. Groundwater ubiquity score (GUS) indexes confirmed the low leaching ability of metolachlor on soils and moderate of carbofuran. The high affinity of carbaryl to CR may explain its pronounced sorption in loam soil and the lowest percolation potential. Carbofuran retention in soils was associated with montmorillonite (Mt) and CR fractions. Meanwhile, metolachlor uptake was related to humic acid and Mt content of the soils. Lower pH enhanced retention of the agrochemicals, except for carbaryl sorption in sandy loam soil. Results of this study highlight that SOM composition and mutual share of individual organic carbon fractions alongside pH may play a crucial role in predicting non-ionic pesticide behavior in soil. Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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13 pages, 6321 KiB

Open AccessArticle

Using Glyphosate on Guarana Seedlings in the Amazon

by Bruna Nogueira Leite Konrad, Sara Cruz Pinheiro, Carla Coelho Ferreira, Evandro Konrad Hoffmann and Sônia Maria Figueiredo Albertino

Molecules 2023, 28(13), 5193; https://doi.org/10.3390/molecules28135193 - 04 Jul 2023

Cited by 1 | Viewed by 810

Abstract

The seed yield of guarana (Paullinia cupana H.B.K. var. sorbilis) is affected by weeds. Management is difficult for Amazon farmers and ranchers, owing to the hot and humid climate prevailing in the region, which makes mechanical control inefficient and leads farmers to [...] Read more.

The seed yield of guarana (Paullinia cupana H.B.K. var. sorbilis) is affected by weeds. Management is difficult for Amazon farmers and ranchers, owing to the hot and humid climate prevailing in the region, which makes mechanical control inefficient and leads farmers to the decision to use herbicides. Herbicide damage to this species is unknown. The objective of this study was to evaluate glyphosate damage to the development and quality of guarana seedlings. The treatments consisted of glyphosate doses at concentrations of 0, 126, 252, 540, 1080, 2160 and 3240 g a.e. ha⁻¹ and were evaluated for 60 days, in two applications. Analyses were performed for biometrics, seedling development, anthracnose and Injury characteristics. Glyphosate caused symptoms of Injury in all doses applied, but lower doses did not interfere with seedling growth and development. There was a correlation between anthracnose severity and increased glyphosate dose. When applied correctly, glyphosate can be an integrated weed management tool for use in guarana crops. Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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14 pages, 3715 KiB

Open AccessArticle

Enantioselective Toxic Effects of Prothioconazole toward Scenedesmus obliquus

by Qingqing Xiang, Ying Zhou and Chengxia Tan

Molecules 2023, 28(12), 4774; https://doi.org/10.3390/molecules28124774 - 15 Jun 2023

Cited by 1 | Viewed by 797

Abstract

Prothioconazole (PTC) is a broad-spectrum triazole fungicide with one asymmetric center and consists of two enantiomers, R-(−)-PTC and S-(+)-PTC. To address the concern of its environmental safety, the enantioselective toxic effects of PTC on Scendesmus obliquus (S. obliquus) were [...] Read more.

Prothioconazole (PTC) is a broad-spectrum triazole fungicide with one asymmetric center and consists of two enantiomers, R-(−)-PTC and S-(+)-PTC. To address the concern of its environmental safety, the enantioselective toxic effects of PTC on Scendesmus obliquus (S. obliquus) were investigated. PTC racemates (Rac-PTC) and enantiomers exhibited dose-dependent acute toxicity effects against S. obliquus at a concentration from 1 to 10 mg·L⁻¹. The 72 h-EC50 value of Rac-, R-(−)-, and S-(+)-PTC is 8.15, 16.53, and 7.85 mg·L⁻¹, respectively. The growth ratios and photosynthetic pigment contents of the R-(−)-PTC treatment groups were higher than the Rac- and S-(+)-PTC treatment groups. Both catalase (CAT) activities and esterase activities were inhibited in the Rac- and S-(+)-PTC treatment groups at high concentrations of 5 and 10 mg·L⁻¹, and the levels of malondialdehyde (MDA) were elevated, which exceeded the levels in algal cells for the R-(−)-PTC treatment groups. PTC could disrupt the cell morphology of S. obliquus and induce cell membrane damage, following the order of S-(+)-PTC ≈ Rac-PTC > R-(−)-PTC. The enantioselective toxic effects of PTC on S. obliquus provide essential information for its ecological risk assessment. Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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13 pages, 929 KiB

Open AccessArticle

Residues and Dietary Risk Assessment of Prohexadione-Ca and Uniconazole in Oryza sativa L. and Citrus reticulata Blanco by Liquid Chromatography-Tandem Mass Spectrometry

by Hui Ye, Yuqin Luo, Yanjie Li, Xiangyun Wang, Hongmei He, Jinhua Jiang, Jianzhong Yu and Changpeng Zhang

Molecules 2023, 28(6), 2611; https://doi.org/10.3390/molecules28062611 - 13 Mar 2023

Viewed by 1609

Abstract

A simple and sensitive method for the simultaneous quantitation of prohexadione-Ca and uniconazole in the field experiment of Oryza sativa L. and Citrus reticulata Blanco was established using solid-phase extraction (SPE) with polymer anion exchange (PAX) and Florisil followed by LC-MS/MS. The method [...] Read more.

A simple and sensitive method for the simultaneous quantitation of prohexadione-Ca and uniconazole in the field experiment of Oryza sativa L. and Citrus reticulata Blanco was established using solid-phase extraction (SPE) with polymer anion exchange (PAX) and Florisil followed by LC-MS/MS. The method demonstrated excellent linearity (R² > 0.999 0), trueness (recoveries between 95~105%), precision (CVs between 0.8~12%), sensitivity, and repeatability (LOQ of 0.05 and 0.01 mg/kg, respectively). Residue tests were conducted in the field at 12 representative sites in China, revealing final concentrations of prohexadione-Ca and uniconazole in brown rice, rice hull, and rice straw to be below 0.05 mg/kg, while in whole citrus fruit and citrus pulp, they were below 0.01 mg/kg. These were below the maximum residue limits specified in China. The chronic dietary risks of prohexadione-Ca and uniconazole in rice crops and citrus fruits were calculated to be 0.48% and 0.91%, respectively. Our research suggests that the chronic risk associated with the daily consumption of rice crops and citrus fruit at the recommended dosage is acceptable. Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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12 pages, 1386 KiB

Open AccessArticle

Method Validation for Multi-Pesticide Residue Determination in Chrysanthemum

by Xinru Wang, Zihan Wang, Jiawei Yu, Luchao Wu, Xinzhong Zhang, Fengjian Luo, Zongmao Chen and Li Zhou

Molecules 2023, 28(3), 1291; https://doi.org/10.3390/molecules28031291 - 29 Jan 2023

Cited by 1 | Viewed by 1472

Abstract

The chrysanthemum can be consumed in various forms, representing the “integration of medicine and food”. Quantitative analysis of multi-pesticide residues in chrysanthemum matrices is therefore crucial for both product-safety assurance and consumer-risk evaluation. In the present study, a simple and effective method was [...] Read more.

The chrysanthemum can be consumed in various forms, representing the “integration of medicine and food”. Quantitative analysis of multi-pesticide residues in chrysanthemum matrices is therefore crucial for both product-safety assurance and consumer-risk evaluation. In the present study, a simple and effective method was developed for simultaneously detecting 15 pesticides frequently used in chrysanthemum cultivation in three matrices, including fresh flowers, dry chrysanthemum tea, and infusions. The calibration curves for the pesticides were linear in the 0.01–1 mg kg⁻¹ range, with correlation coefficients greater than 0.99. The limits of quantification (LOQs) for fresh flowers, dry chrysanthemum tea, and infusions were 0.01–0.05 mg kg⁻¹, 0.05 mg kg⁻¹, and 0.001–0.005 mg L⁻¹, respectively. In all selected matrices, satisfactory accuracy and precision were achieved, with recoveries ranging from 75.7 to 118.2% and relative standard deviations (RSDs) less than 20%. The validated method was then used to routinely monitor pesticide residues in 50 commercial chrysanthemum-tea samples. As a result, 56% of samples were detected with 5–13 pesticides. This research presents a method for the efficient analysis of multi-pesticide residues in chrysanthemum matrices. Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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13 pages, 1422 KiB

Open AccessArticle

A Nationwide Study of Residual Fate of Fluxapyroxad and Its Metabolites in Peanut Crops Across China: Assessment of Human Exposure Potential

by Xi Wang, Li Chen, Xin Ren, Shanshan Kang, Wei Li and Zenglong Chen

Molecules 2023, 28(1), 194; https://doi.org/10.3390/molecules28010194 - 26 Dec 2022

Viewed by 1729

Abstract

Elaborating on the residual fate of fluxapyroxad and its metabolites based on their nationwide application was vital to protect the human population from their hazardous effects. In this study, a rapid and sensitive analytical method was developed to trace fluxapyroxad and two of [...] Read more.

Elaborating on the residual fate of fluxapyroxad and its metabolites based on their nationwide application was vital to protect the human population from their hazardous effects. In this study, a rapid and sensitive analytical method was developed to trace fluxapyroxad and two of its metabolites in peanut matrices using an ultrahigh chromatography method coupled with mass spectrometry (UHPLC–MS/MS) within 3.5 min. The occurrence, pharmacokinetic degradation and terminal magnitudes of fluxapyroxad were reflected in the original deposition of 8.41–38.15 mg/kg, half–lives of 2.5–8.6 d and final concentrations of 0.004–37.38 mg/kg in peanut straw. The total concentrations of fluxapyroxad in peanut straw (0.04–39.28 mg/kg) were significantly higher than those in peanut kernels (<0.001–0.005 mg/kg) and an obvious concentration effect was observed in fresh (0.01–11.56 mg/kg) compared dried peanut straw (0.04–38.97 mg/kg). Fluxapyroxad was demethylated to 3–(difluoromethyl)–N–(3′,4′,5′–trifluoro[1,1′–biphenyl]–2–yl)–1H–pyrazole–4–carboxamide (M700F008, 0.02–5.69 mg/kg) and further N–glycosylated to 3–(difluoromethyl)–1–(ß–D–glucopyranosyl)–N–(3′,4′,5′–triflurobipheny–2–yl)–1H–pyrzaole–4–carboxamide (M700F048, 0.04–39.28 mg/kg).The risk quotients of the total fluxapyroxad for the urban groups were significantly higher than those for the rural groups, and were both negatively correlated with the age of the groups, although both acute (ARfD%, 0.006–0.012%) and chronic (ADI%, 0.415–1.289%) risks are acceptable for the human population. The high-potential health risks of fluxapyroxad should be continuously emphasized for susceptible toddlers (1–3 years), especially those residing in urban areas. Full article

(This article belongs to the Special Issue Environmental Fate and Residue, Toxicity, and Risk Assessment of Pesticides)

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