Physicochemical Properties Of Pesticides Research Articles

Transfer of pesticides and metabolites in corn: Production, processing, and livestock dietary burden

Corn stover is widely used in livestock feed but has received limited attention regarding its potential risks. In this study, pesticide residues were monitored across 12 provinces in China, and terminal residues of four pesticides, chlorantraniliprole, thiamethoxam, epoxiconazole, and pyraclostrobin, were tested. In addition, the silage processing experiment was conducted. All processing factors (PF) were <1, indicating pesticide degradation. The physicochemical properties of pesticides, especially log P, were related to degradation efficiency. Pesticides with higher log P values showed higher PFs (0.43 to 0.85), indicating lower degradation efficiency. The dietary burden of livestock before and after silage processing was calculated using OECD livestock dietary burden calculator. Results showed that after silage fermentation, the dietary burden was reduced by 28.8 % to 79.2 %. Throughout the entire production and processing process, the fastest degradation of all pesticides in whole corn was primarily observed from the pesticide application time to the harvest time, with some pesticides also showing accelerated degradation during subsequent processing stages. Therefore, in actual production, especially for pesticides which are difficult to degrade, appropriate extension of the safety interval or selection of suitable processing methods can be taken to further reduce pesticide residues in agricultural products.

Modeling the impact of pesticide drift deposition on off-field non-target receptors

Pesticide application can result in residue drift deposition in off-field areas, which can be harmful to non-target organisms inhabiting adjacent off-field environments. In order to comprehend the impact of pesticide drift deposition on off-field non-target organisms, an integrated modeling approach was incorporated into the life cycle analysis perspective for the assessment of their exposure to pesticide residues and the characterization of their human toxicity and ecotoxicity potentials. The modeling assumption comprises four modeling scenarios: children & cattle & sensitive crops (tomatoes) based on exposure assessment, and the continent-scale human health toxicity & ecotoxicity under a life cycle analysis perspective. The simulation results for the nearby off-field exposure scenario revealed that pesticide dissipation kinetics in environments and drift deposition type were two important factors influencing non-target organisms' exposure to pesticide residues deposited in off-field environments. The continental scenario simulated via USEtox revealed that considering off-field drift deposition resulted in lower simulated human toxicity potentials of pesticides when compared to simulation results that did not consider drift deposition, given that pesticide residues remaining within the treated field contributed the most to overall human exposure. Taking drift deposition into account, on the other hand, could result in higher or lower simulated ecotoxicity potentials of pesticides than not taking drift deposition in off-field areas into account, depending on the physicochemical properties of pesticides. The proposed modeling approach, which is adaptable to drift deposition types and chemical species, can aid in investigating the off-field impacts of pesticide residues. Future research will incorporate spatiotemporal factors to characterize region-specific drift deposition functions and pesticide fate in off-field environments to conduct site-specific impact assessments.

Sorption and mobility assessment of tembotrione in soils of upper, trans and middle Gangetic plain zones of India.

The presence of undesired agrochemicals residues in soil and water poses risks to both human health and the environment. The behavior of pesticides in soil depends both on the physico-chemical properties of pesticides and soil type. This study examined the adsorption-desorption and leaching behavior of the maize herbicide tembotrione in soils of the upper (UGPZ), trans (TGPZ) and middle Gangetic plain zones of India. Soil samples were extracted using acetone followed by partitioning with dichloromethane, whereas liquid-liquid extraction using dichloromethane was used for aqueous samples. Residues of tembotrione and its metabolite TCMBA, {2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy) methyl] benzoic acid}, were quantified using liquid chromatography-tandem mass spectrometry. The data revealed that tembotrione adsorption decreased with increasing pH and dissolved organic matter but increased with salinity. The maximum adsorption occurred at pH4, 0.01m sodium citrate and 4g/L NaCl, with corresponding Freundlich constants of 1.83, 2.28 and 3.32, respectively. The hysteresis index <1 indicated faster adsorption than desorption. Leaching studies under different flow conditions revealed least mobility in UGPZ soil and high mobility in TGPZ soil, consistent with groundwater ubiquity scores of 4.27 and 4.81, respectively. Soil amendments decreased tembotrione mobility in the order: unamended > wheat straw ash > wheat straw > farm yard manure > compost. The transformation of tembotrione to TCMBA and its mobility in soil columns were also assessed.

Residue changes, degradation, processing factors and their relation between physicochemical properties of pesticides in peanuts during multiproduct processing

This study systematically investigates the residue changes, processing factors (PFs), and relation between the physicochemical properties of pesticides during peanut processing. Results revealed that peeling, washing, and boiling treatments removed partial or substantial pesticide residues from peanuts with PFs of 0.29–1.10 (most <1). By contrast, pesticides appeared to be partially concentrated during roasting, stir-frying, and deep-frying peanuts with PFs of 0.16–1.25. During oil pressing, 13 of the 28 pesticides were concentrated in the peanut oil (PF range: 1.06–2.01) and 25 of the pesticides were concentrated in the peanut meal (1.07–1.46). Physicochemical parameters such as octanol–water partition coefficient, degradation point, molecular weight, and melting point showed significant correlations with PFs during processing. Notably, log Kow exhibited strong positive correlations with the PFs of boiling, roasting, and oil pressing. Overall, this study describes the fate of pesticides during multiproduct processing, providing guidance to promote the healthy consumption of peanuts for human health.

Regulatory landscape of risk assessment of pesticide residues in processed foods in India: a perspective.

In India, the levels of pesticide residues in Raw Agricultural Commodities (RAC) are being subjected to adequate legal regulations, and the health-risks associated with them are determined from time to time adhering to global standards. Since RACs are generally consumed by humans as the processed foods (PF), it is imperative to monitor the levels of pesticide residues in them in order to approach a realistic analysis of dietary exposure and concomitant health risk assessment. In India, production and consumption of PFs have a rising trend and hence it is indispensable to monitor the residue levels of pesticides in largely consumed PFs. Depending on the processing methods and physicochemical properties of pesticides, the residue levels may decrease or increase in a PF when compared to the corresponding RAC. While obtaining data on processing factors (Pf), it is pragmatic to focus on those situations in which the residues get concentrated following the processing step. Currently, regulatory agencies of several countries and the CODEX have determined the levels of pesticide residues in processed agriculture commodities, arrived at the Pfs, and fixed the maximum residue levels. Since consumption of PFs in India has tremendously increased in recent times and there is paucity of data about their health risks/benefits, it is imminent to deliberate on the complexities associated with the issues of adopting the Pfs generated by other regulatory agencies and subsequently examine the possibilities of generating the required data on Pfs on a priority basis to enable a comprehensive risk assessment.

A Review on Adsorption and Desorption of Different Pesticides in Various Soil

Pesticides are important to the success of agriculture as well as an inevitable factor to maintain good public health. Over the years, the consumption of pesticides has increased manifold, particularly during the past two decades. However, this increase has caused great concern over the presence of residues or leftover pesticides in the environment. The understanding of adsorption and desorption behavior of different pesticides is an important phenomenon to describe the fate of pesticide in soil and other environmental compartment like water and sediment. The soil is considered as ultimate sink of pesticide as these were reached to soil directly or indirectly from the point/non-point sources. Adsorption–desorption processes are necessary in understanding pesticides retention behavior and its potential mobility within the soil. The behavior of pesticides in the soil depends on factors such as the physico-chemical properties of pesticides, the active surface of mineral, organic components and the amount of the pesticide applied. Henceforth, adsorption and desorption of soil applied pesticides needed to deal with greater sincerity. This review primarily ascertains dominant properties of pesticides including surface area, pH, surface functional groups, carbon content and aromatic structure and evaluate the adsorption and desorption of pesticide in agricultural soils. In addition, a vision for future research prospects has been anticipated by considering the pesticide bioavailability as residues in soil, influence of soil organic matter, clay content, pH and soil temperature on pesticide removal, pesticide properties and its behavior in soils.

National assessment of spatiotemporal loss in agricultural pesticides and related potential exposure risks to water quality in China

Pesticide loss during agricultural development has a serious effect on related water quality, and the critical concern is quantifying the potential exposure risks that pesticide loss pose to water quality at the national scale. In this study, an integrated assessment framework is proposed to scale emission factors from 232 monitoring plots to the national scale, while also considering the physicochemical properties of pesticides in dissolved or adsorbed forms. Based on the results of this study, the total pesticide emissions increased by 29.39% from 146.55 tons in 2004 to 189.62 tons in 2013 and the average loss intensities of insecticides, herbicides and fungicides were 35.25 g/km2, 44.24 g/km2 and 48.57 g/km2, respectively. Central and Southeastern China are identified as hotspots for pesticide loss, while the proportions of high or extremely high-risk areas mainly comprise >50% of farmland. In addition, single-field crops and single-crop rice are the major cropping patterns for pesticide loss in Northern and Southern China. Our results identify key areas for the management of pesticides at the national scale and have direct implications for environmental policies on reducing the potential exposure risk of agricultural pesticides to water quality.

Dicationic Ionic Liquids of Herbicide 2,4-Dichlorophenoxyacetic Acid with Reduced Negative Effects on Environment.

Due to high volatility and water solubility, 2,4-dichlorophenoxyacetic acid (2,4-D) can easily enter into the atmosphere and water bodies by volatilization, drift, leaching, or runoff, which results in potential threats to the environment and human health. The physicochemical properties of pesticides can be regulated by preparing their ionic liquids. In this work, a series of dicationic ionic liquids (DILs) of 2,4-D were prepared to reduce its environmental risk and enhance herbicidal activity. The solubility, octanol-water partition coefficient, surface tension, and volatilization rate results of DILs showed that these properties could be optimized by choosing appropriate countercations. Compared to 2,4-D ammonium salt, DILs have lower volatility, water solubility, and surface tension as well as higher lipophilicity. Benefiting from optimized physicochemical properties, DILs HIL8-12 exhibited better herbicidal activity against three typical broadleaf weeds than 2,4-D ammonium salt, and their fresh weight inhibition rates increased by 2.74-46.84%. The safety assessment experiment indicated that DILs were safer to wheat than commercialized forms of 2,4-D. The DILs could reduce the environmental risk of 2,4-D caused by high volatility and water solubility and would be potential alternatives to its commercialized formulations.

Tebuconazole and Azoxystrobin Residue Behaviors and Distribution in Field and Cooked Peanut.

Residue behaviors of tebuconazole and azoxystrobin in field condition and the variation of their residue levels during the boiling process were evaluated. The terminal residues of peanut kernels were determined by using a modified QuEChERS method (quick, easy, cheap, effective, rugged, and safe) by means of the optimization of the novel purification procedure with multiwalled carbon nanotubes (MWCNTs) and Fe3O4-magnetic nanoparticle (Fe3O4-MNP) in the presence of an external magnetic field, and the terminal residues were all at trace level at harvest time. The residues in shells were detected as well to investigate the distribution in peanuts. Tebuconazole and azoxystrobin residue levels varied before/after boiling in kernels and shells to different degrees due to various factors, such as the modes of action and physicochemical properties of pesticides. The residues have been transferred from peanut into the infusion during boiling with the higher percentage of azoxystrobin as its lower logKow. The processing factors (PFs) for tebuconazole and azoxystrobin after processing were <1, indicating that home cooking in this study could reduce the residue levels in peanut. Risk assessment showed there was no health risk for consumers.

Pesticide contamination in groundwater bodies in the Júcar River European Union Pilot Basin (SE Spain).

The change from a traditional agricultural model to a modern, more productive one, coupled with population growth, has entailed an increased consumption of water, fertilizers and pesticides. This transformation has led to a greater risk of groundwater contamination. This study has analysed for this purpose a total of 314 samples (period 2010-2013). In addition, 332 samples from the Mancha Oriental groundwater body (period 2001-2003) were also examined in order to gain a better perspective on the temporal evolution of pesticides in groundwater bodies. Using this database, this study aims to characterize pesticide pollution and to examine possible processes. Triazine herbicides are the most common pesticides found and also appear in the highest concentrations, with terbuthylazine having a noteworthy concentration of 900ng/L. The irrigated agriculture and the physicochemical properties of pesticides are the most important factors influencing the concentration and type of pesticides that can reach groundwater. The spatial distribution of nitrate and pesticides do not correspond as they would if the two behaved similarly. Pesticides can completely biodegrade before reaching the saturated zone, but it is also possible that their degradation products have not been analysed and, therefore, their concentrations are underestimated.

Sorption and desorption of indaziflam degradates in several agricultural soils

Processes regulating pesticide fate in the environment are influenced by the physicochemical properties of pesticides and soils. Sorption and desorption are important processes as they regulate the movement of pesticides in soil. Although sorption-desorption is widely studied for herbicides, studies involving their metabolites in soil are scarce. Sorption and desorption of indaziflam metabolites (indaziflam-triazinediamine (FDAT), indaziflam-triazine-indanone (ITI) and indaziflam-carboxilic acid (ICA)) were investigated in six Brazilian (BRA) soils and three United States (USA) soils with different physicochemical properties. The Freundlich equation described sorption of the metabolites for all soils (R2 > 0.98; 1/n ~ 1). Sorption order (Kf) was ITI > ICA > FDAT. Mean values of Kf,oc were 453, 289, and 81 (BRA) and 444, 48, and 48 (USA) for metabolites ITI, ICA, and FDAT respectively. Desorption was hysteretic for all metabolites in all soils. These results suggest that these metabolites fall in the classification range of mobile to moderately mobile in soils.

Measuring Leaf Penetration and Volatilization of Chlorothalonil and Epoxiconazole Applied on Wheat Leaves in a Laboratory-Scale Experiment.

Estimation of pesticide volatilization from plants is difficult because of our poor understanding of foliar penetration by pesticides, which governs the amount of pesticide available for volatilization from the leaf surface. The description of foliar penetration is still incomplete because experimental measurements of this complex process are difficult. In this study, the dynamics of leaf penetration of C-chlorothalonil and C-epoxiconazole applied to wheat leaves were measured in a volatilization chamber, which allowed us to simultaneously measure pesticide volatilization. Fungicide penetration into leaves was characterized using a well-defined sequential extraction procedure distinguishing pesticide fractions residing at different foliar compartments; this enabled us to accurately measure the penetration rate constant into the leaves. The effect of pesticide formulation was also examined by comparing formulated and pure epoxiconazole. We observed a strong effect of formulation on leaf penetration in the case of a systemic product. Furthermore, the penetration rate constant of formulated epoxiconazole was almost three times that of pure epoxiconazole (0.47 ± 0.20 and 0.17 ± 0.07, respectively). Our experimental results showed high recovery rates of the radioactivity applied within the range of 90.5 to 105.2%. Moreover, our results confirm that pesticide physicochemical properties are key factors in understanding leaf penetration of pesticide and its volatilization. This study provides important and useful parameters for mechanistic models describing volatilization of fungicides applied to plants, which are scarce in the literature.

Efeito do processamento industrial e doméstico de alimentos nos níveis de resíduos de agrotóxicos

Pesticide residues in food pose a great risk to public health due to the harmful effects they can cause. Due to the use of pesticides in food production, as well as through environmental contamination, residues can be found in fresh, cooked and processed foodstuffs. Most food is consumed after industrial or household processing, such as washing, peeling, thermal treatments and sterilization. Several studies have shown that these procedures may, in some cases, reduce residue levels. The efficiency of residues removal depends on the processing involved and the physicochemical properties of pesticides, such as stability and interaction with food. This review aims to highlight the results of studies on the effects of various processes on the levels of pesticide residues in different food, especially the removal efficiency of the compounds. This information is useful to assess the possibility of minimizing the risk of consumer exposure to pesticide residues in foods, becoming an important tool for food safety.

Sorption of selected pesticides on soils, sediment and straw from a constructed agricultural drainage ditch or pond

Buffer zones such as ponds and ditches are used to reduce field-scale losses of pesticides from subsurface drainage waters to surface waters. The objective of this study was to assess the efficiency of these buffer zones, in particular constructed wetlands, focusing specifically on sorption processes. We modelled the sorption processes of three herbicides [2-methyl-4-chlorophenoxyacetic acid (2,4-MCPA), isoproturon and napropamide] and three fungicides (boscalid, prochloraz and tebuconazole) on four substrates (two soils, sediment and straw) commonly found in a pond and ditch in Lorraine (France). A wide range of Freundlich coefficient (K fads) values was obtained, from 0.74 to 442.63 mg(1 - n) L (n) kg(-1), and the corresponding K foc values ranged from 56 to 3,725 mg(1 - n) L (n) kg(-1). Based on potential retention, the substrates may be classified as straw >> sediments > soils. These results show the importance of organic carbon content and nature in the process of sorption. Similarly, the studied pesticides could be classified according to their adsorption capacity as follows: prochloraz >> tebuconazole-boscalid > napropamide >> MCPA-isoproturon. This classification is strongly influenced by the physico-chemical properties of pesticides, especially solubility and K oc. Straw exhibited the largest quantity of non-desorbable pesticide residues, from 12.1 to 224.2 mg/L for all pesticides. The presence of plants could increase soil-sediment sorption capacity. Thus, establishment and maintenance of plants and straw filters should be promoted to optimise sorption processes and the efficiency of ponds and ditches in reducing surface water pollution.

Rapid and Simple Analysis of Pesticides Persisting on Green Pepper Surfaces Swabbing with Solvent-Moistened Cotton

A rapid and simple nondestructive extraction (NDE) method that includes wiping off of systemic neonicotinoid insecticides has been developed to streamline sample pretreatment procedures conducted before chromatographic determination. Pesticide residues were extracted from green pepper surfaces by swabbing them with absorbent cotton moistened with acetone or acetonitrile. After spraying of pesticides, the extraction rate decreased gradually, except for thiacloprid. Presumably, extraction rates depend on the physicochemical properties of pesticides, especially water solubility. It was thought that the applicability of the proposed method greatly depended on the systemic speed of each pesticide, and water solubility was placed as the index that was important to making certain. Direct analysis of some insecticides persisting on sample surfaces has been possible only by extraction before chromatographic determination. These findings indicate strongly that the proposed NDE method has collateral conditions, but it appears promising for on-site pretreatment for pesticide residue analysis.

Airborne residues resulting from use of methyl parathion, molinate and thiobencarb on rice in the sacramento valley, California

In connection with requirements of California's Toxic Air Contaminant Act, 24-h ambient air samples were collected using an XAD-4 resin trap technique capable of simultaneously collecting methyl parathion, methyl paraoxon, molinate and thiobencarb. Sampling was conducted on rooftops of public buildings located in four towns in two counties where methyl parathion, molinate and thiobencarb were used in significant quantities, and at a background site located in a county where no use occurred, for four intervals each week for 5 weeks during the springtime application period of 1986. Satisfactory recoveries (greater than 66%) were obtained from dynamic spiking experiments, and the precision from field replicates was consistently less than 50% relative standard deviation using a protocol designed to accommodate a large number of samples. Daily maximum average concentrations (and the range in averages for all sites over the 19 and 20 sampling days in the two-county use area) were 25.7 ng/m3 (0.2-6.2 ng/m3) for methyl parathion, 3.1 ng/m3 (<0.5-0.8 ng/m3) for methyl paraoxon, 1,720 ng/m3 (60-650 ng/m3) for molinate and 250 ng/m3 (12.9-67.8 ng/m3) for thiobencarb. Concentrations correlated well with reported uses of methyl parathion and molinate in the general vicinity of the sampling sites. The likely sources of observed residue levels, based upon the method of application and pesticide physicochemical properties, were spray drift during application for methyl parathion, vapor-phase oxidation of parent thion for methyl paraoxon, and postapplication volatilization from field water for molinate and thiobencarb.

AIRBORNE RESIDUES RESULTING FROM USE OF METHYL PARATHION, MOLINATE AND THIOBENCARB ON RICE IN THE SACRAMENTO VALLEY, CALIFORNIA

In connection with requirements of California's Toxic Air Contaminant Act, 24-h ambient air samples were collected using an XAD-4 resin trap technique capable of simultaneously collecting methyl parathion, methyl paraoxon, molinate and thiobencarb. Sampling was conducted on rooftops of public buildings located in four towns in two counties where methyl parathion, molinate and thiobencarb were used in significant quantities, and at a background site located in a county where no use occurred, for four intervals each week for 5 weeks during the springtime application period of 1986. Satisfactory recoveries (greater than 66%) were obtained from dynamic spiking experiments, and the precision from field replicates was consistently less than 50% relative standard deviation using a protocol designed to accommodate a large number of samples. Daily maximum average concentrations (and the range in averages for all sites over the 19 and 20 sampling days in the two-county use area) were 25.7 ng/m3 (0.2-6.2 ng/m3) for methyl parathion, 3.1 ng/m3 (<0.5-0.8 ng/m3) for methyl paraoxon, 1,720 ng/m3 (60-650 ng/m3) for molinate and 250 ng/m3 (12.9-67.8 ng/m3) for thiobencarb. Concentrations correlated well with reported uses of methyl parathion and molinate in the general vicinity of the sampling sites. The likely sources of observed residue levels, based upon the method of application and pesticide physicochemical properties, were spray drift during application for methyl parathion, vapor-phase oxidation of parent thion for methyl paraoxon, and postapplication volatilization from field water for molinate and thiobencarb.

A chamber for measuring volatilization of pesticides from model soil and water disposal systems

A chamber for measuring volatilization of pesticides from model soil pit and evaporation pond disposal systems gave 72–86% recoveries of volatilized chemical for six pesticides. Volatilization measurements from a glass surface and from water correlated well with pesticide physico-chemical properties and previously published work.

Distribution, transport, and fate of the insecticides malathion and parathion in the environment.

The environmental dynamics of pesticides are influenced largely by the various factors operating in the environment and the physicochemical and biological properties of pesticides. In the broad sense, the environment is divided into four major components, namely, atmosphere (air), hydrosphere (water), lithosphere (soil), and biosphere (biota), each possessing its own physical and chemical and/ or biological properties. The biotic and abiotic elements in each component influence the dynamics of pesticides. The environmental dynamics of pesticides are further influenced by the physicochemical properties of pesticides. Such properties of pesticides as hydro- or lipo-philicity, partition coefficients, adsorption or chemiosorption, vapor pressure, and volatility determine the ultimate fate of pesticides in the living and nonliving portions of the sytems.