Determination of Pesticide Residues in Selected Vegetables and Fruits From A Local Market of Lahore, Pakistan

Adsorption of trace heavy metals through organic compounds enriched biochar using isotherm adsorption and kinetic models

Trace heavy metals such as copper and nickel, when exceeds a certain level, cause detrimental effects on the ecosystem. The current study examined the potential of organic compounds enriched rice husk biochar (OCEB's) to remove the trace heavy metals from an aqueous solution in four steps. In 1st step, biochar' physical and chemical properties were analyzed through scanning electron microscope (SEM) and Fourier transforms infrared spectroscopy (FTIR). In the 2nd step, two biochar vis-a-vis glycine, alanine enriched biochar (GBC, ABC) was selected based on their adsorption capacity of four different metals Cr, Cu, Ni and Pb (chromium, copper, nickel, and lead). These two adsorbents (GBC, ABC) were further used to evaluate the best interaction of biochar for metal immobilization based on varying concentrations and times. Langmuir isotherm model suggested that the adsorption of Ni and Cu on the adsorbent surface supported the monolayer sorption. The qmax value of GBC for Cu removal increased by 90% compared to SBC (Simple rice husk biochar). The interaction of Cu and Ni with GBC and ABC was chemical, and 10 different time intervals were studied using pseud first and second-order kinetics models. The current study has supported the pseudo second-order kinetic model, which exhibited that the sorption of Ni and Cu occurred due to the chemical processes. The % removal efficiency with GBC was enhanced by 21% and 30% for Cu and Ni, respectively compared to the SBC. It was also noticed that GBC was 21% more efficient for % removal efficiency than the CBC. The study's findings supported that organic compound enriched rice husk biochar (GBC and ABC) is better than SBC for immobilizing the trace heavy metals from an aqueous solution.

Pesticides in vegetable production in Bangladesh: A systemic review of contamination levels and associated health risks in the last decade

This paper reviewed the published data on the levels of different pesticide residues in vegetables (tomato, eggplant, beans, gourds, cauliflower, cabbage, cucumber, potato, carrot, onion, red chilli, red amaranth, lady's finger, spinach, coriander, and lettuce) from Bangladesh in the last decade. Vegetable production in Bangladesh has increased tremendously (37.63%) compared to the last decades, along with its pesticide use. The most observed pesticide groups used in vegetable production were organophosphorus, pyrethroids, carbamate, organochlorine, nereistoxin analogue group, and neonicotinoids. More specifically, chlorpyrifos, dimethoate, diazinon, and malathion were the most used pesticides. More than 29% of the vegetable samples (1577) were contaminated with pesticide residue; among the contaminated samples (458), most cases (73%) exceeded the maximum residue limits (MRLs). The pesticide-contaminated vegetables were cucumber (51%), tomato (41%), cauliflower (31%), miscellaneous vegetables (36%), eggplant (29%), beans (23%), cabbage (18%), and gourds (16%). Among the pesticide-contaminated samples, vegetables with above MRL were gourds (100%), beans (92), tomato (78%), eggplant (73%), miscellaneous vegetables (69%), cucumber (62%), cabbage (50%), cauliflower (50%) (p < 0.05). It was also observed that a single vegetable was often contaminated with multiple pesticides, and farmers did not follow a proper withdrawal period while using pesticides. Hazard quotation (HQ>1) was observed in adolescents and adults in tomato, eggplant, beans, cauliflower, cabbage, cucumber, lady's finger, lettuce, and coriander. There was no health risk observed (HQ<1) in gourds, potato, carrot, onion, red chilli, red amaranth, spinach, and okra. The highest acute and chronic HQ (aHQ, cHQ) was observed for cypermethrin (bean) in adolescents (aHQ=255, cHQ= 510) and adults (aHQ=131, cHQ=263). It was also observed that these pesticides harmed air, soil, water, and non-target organisms. Nevertheless, the review will help the government develop policies that reduce pesticide use and raise people's awareness of its harmful effects.

The analysis of pesticides and fungicides in the inhibition of human and rat placental 3β-hydroxysteroid dehydrogenase activity: mode of inhibition and mechanism

3β-Hydroxysteroid dehydrogenase/steroid Δ^5,4-isomerase 1 (3β-HSD1) plays a critical role in the biosynthesis of progesterone from pregnenolone in the human placenta to maintain normal pregnancy. Whether they inhibit placental 3β-HSD1 and mode of inhibition remains unclear. In this study, we screened 21 pesticides and fungicides in five classes to inhibit human 3β-HSD1 and compared them to rat homolog 3β-HSD4. 3β-HSD activity was measured by catalyzing pregnenolone to progesterone in the presence of NAD⁺. Of the 21 chemicals, azoles (difenoconazole), thiocarbamates (thiram and ferbam) and organochlorine (hexachlorophene) significantly inhibited human 3β-HSD1 with half maximal inhibitory concentration (IC₅₀) values of 2.77, 0.24, 0.68, and 17.96 μM, respectively. We also found that difenoconazole, ferbam and hexachlorophene are mixed/competitive inhibitors of 3β-HSD1 while thiram is a mixed/noncompetitive inhibitor. Docking analysis showed that difenoconazole and hexachlorophene bound steroid-binding site. Difenoconazole and hexachlorophene except thiram and ferbam also significantly inhibited rat 3β-HSD4 activity with IC₅₀ of 1.12 and 2.28µM, respectively. Thiram and ferbam significantly inhibited human 3β-HSD1 possibly by interfering with cysteine residues, while they had no effects on rat 3β-HSD4. In conclusion, some pesticides potently inhibit placental 3β-HSD, leading to the reduction of progesterone formation.

Modified matrix solid phase dispersion-HPLC method for determination of pesticide residue in vegetables and their impact on human health: A risk assessment

The use of pesticides is unavoidable in agricultural practices. This class of chemicals is highly toxic for the environment as well as for humans. The present work was carried out to assess the presence of some pesticides (diafenthiuron, lufenuron, azoxystrobin, difenoconazole, and chlorothalonil) residues in five of the very commonly used vegetables (eggplant, capsicum, apple gourd, cauliflower, and sponge gourd). Matrix solid phase dispersion (MSPD) technique was used to extract the pesticides and subsequently their quantification was performed through high performance liquid chromatography (HPLC) coupled to ultraviolet-visible (UV-Vis) detector. The elution was accomplished at wavelength of 254 nm by injecting 20 µL of standards or samples into chromatographic system. The mobile phase consisted of acetonitrile and water (80:20 v/v), where the flow rate was adjusted at 1.0 ml/min. The linearity was good (R ² ≥ 0.994) over a concentration range from 20 to 100 μg/ml for the investigated pesticides. The low detection limits showed a quite appreciable potential of the method to detect (1.12-1.61 μg/L) and quantify (3.73-5.36 μg/ml) the pesticides under study. The accuracy was demonstrated in terms of percent recovery which ranged between 88.5% and 116.9% for all the pesticides under investigation. These results justify the suitability of the technique for the intended purpose. The concentration of difenoconazole in apple gourd (20.97 mg/kg), cauliflower (10.28 mg/kg), and sponge gourd (40.32 mg/kg) whereas diafenthiuron in cauliflower (0.66 mg/kg) exceeded the maximum residue level (MRLs) as defined by Food and Agriculture Organization of the United Nations and the World Health Organization (FAO/WHO). Target hazard quotient (THQ) values of difenoconazole and diafenthiuron (except for adults) were more than one which indicates the significant effect on human health on consumption of apple gourd, cauliflower, and sponge gourd.

A Label-Free Electrochemical Aptasensor Based on Zn/Fe Bimetallic MOF Derived Nanoporous Carbon for Ultra-Sensitive and Selective Determination of Paraquat in Vegetables

Paraquat (PQ) has high acute toxicity, even at low concentrations. For most people, the main pathway of exposure to PQ is through the diet. Therefore, the development of simple and efficient methods for PQ testing is critical for ensuring food safety. In this study, a new electrochemical detection strategy for paraquat is proposed based on the specific binding of PQ to its nucleic acid aptamer. Firstly, the Zn/Fe bimetallic ZIF derived nanoporous carbon (Zn/Fe-ZIF-NPC) and nickel hexacyanoferrate nanoparticles (NiHCF-NPs) were sequentially modified onto the glassy carbon electrode (GCE). NiHCF-NPs served as the signal probes, while Zn/Fe-ZIF-NPC facilitated electron transfer and effectively enhanced the sensing signal of NiHCF-NPs. Au nanoparticles (AuNPs) were then electrodeposited on the NiHCF-NPs/Zn/Fe-ZIF-NPC/GCE and then the thiolated aptamer was assembled on the AuNPs/NiHCF-NPs/Zn/Fe-ZIF-NPC/GCE via Au-S bonding. When incubated with PQ, the formation of PQ–aptamer complexes delayed the interfacial electron transport reaction of NiHCF-NPs, which caused a decrease in the current signals. As a result, simple and highly sensitive detection of PQ can be readily achieved by detecting the signal changes. A linear range was obtained from 0.001 to 100 mg/L with a detection limit as low as 0.34 μg/L. Due to the recognition specificity of the aptamer to its target molecule, the proposed method has excellent anti-interference ability. The prepared electrochemical aptasensor was successfully used for PQ assay in lettuce, cabbage and agriculture irrigation water samples with recoveries ranging from 96.20% to 104.02%, demonstrating the validity and practicality of the proposed method for PQ detection in real samples.

A Cheminformatics Study Regarding the Human Health Risks Assessment of the Stereoisomers of Difenoconazole

Difenoconazole is a chemical entity containing two chiral centers and having four stereoisomers: (2R,4R)-, (2R,4S)-, (2S,4R)- and (2S,4S)-difenoconazole, the marketed product containing a mixture of these isomers. Residues of difenoconazole have been identified in many agricultural products and drinking water. A computational approach has been used to evaluate the toxicological effects of the difenoconazole stereoisomers on humans. It integrates predictions of absorption, distribution, metabolism, excretion and toxicity (ADMET) profiles, prediction of metabolism sites, and assessment of the interactions of the difenoconazole stereoisomers with human cytochromes, nuclear receptors and plasma proteins by molecular docking. Several toxicological effects have been identified for all the difenoconazole stereoisomers: high plasma protein binding, inhibition of cytochromes, possible hepatotoxicity, neurotoxicity, mutagenicity, skin sensitization potential, moderate potential to produce endocrine disrupting effects. There were small differences in the predicted probabilities of producing various biological effects between the distinct stereoisomers of difenoconazole. Furthermore, there were significant differences between the interacting energies of the difenoconazole stereoisomers with plasma proteins and human cytochromes, the spectra of the hydrogen bonds and aromatic donor–acceptor interactions being quite distinct. Some distinguishing results have been obtained for the (2S,4S)-difenoconazole: it registered the highest value for clearance, exposed reasonable probabilities to produce cardiotoxicity and carcinogenicity and negatively affected numerous nuclear receptors.

Impact of sonolytic ozonation (O3/US) on degradation of pesticide residues in fresh vegetables and fruits: Case study of Faisalabad, Pakistan

High pesticide residues in fresh produce is a serious food safety issue. This study was aimed at assessing the pesticides residues in some important vegetables and fruits marketed in Faisalabad, Pakistan and the impact of sonolytic ozonation (O₃/US) treatment in removing these contaminants. From a short grower's survey, five registered and mostly used pesticides (acetamiprid, carbendazim, imidacloprid, thiacloprid and thiamethoxam) were identified. A time optimization trial of O₃/US application (05, 10 and 15 min) on okra, showed that 10 min treatment significantly reduced three identified chemicals (thiamethoxam 100 %, imidacloprid and thiacloprid 97.17 %), without any adverse effect on its quality. In follow up trial, five fresh vegetables (cauliflower, chillies, cucumber, spinach and tomato) three fresh fruits (grapes, guava and peach) collected from three markets of Faisalabad, were pooled together to have uniform samples. Vegetables and fruits were treated with O₃/US for 10 and 6 min, respectively, along with control (simple tap wash) for determining the impacts on pesticides degradation. Samples were processed for extraction, clean up and analysis using HPLC-UV-Vis in isocratic mode. The data revealed the presence of five mentioned chemicals, with an accumulative mean residue of 9.006 and 1.921 µg/g in tested vegetables and fruits, respectively. After subjecting to O₃/US, the accumulative chemical residues were reduced to 3.214 µg/g (64.313 %) and 1.064 (44.6 %) in treated vegetables and fruits respectively. Irrespective of fresh produce, the mean residues of thiamethoxam, imidachloprid, acetamiprid and thiachloprid and carbendazim were reduced by 99.3 %, 52.6 %, 65.2 %, 87.3 % and 72% respectively. It was concluded that sonolytic ozonation treatment was effective in significant reduction of pesticide residues from vegetables and fruits and thus can be employed as a good food safety practice at culinary level to reduce the associated health hazardous risks.

Simple colorimetric screening of paraquat residue in vegetables evaluated by localized surface plasmon resonance of gold nanoparticles

The contamination of paraquat in vegetables is widely connected with human health risks, leading to the research interest in developing a paraquat sensing system. This work reports a simple detection method of paraquat based on the electrostatic interaction of paraquat and the negatively charged gold nanoparticles (AuNPs), resulting in the changes of colors from red to blue and the shifting of localized surface plasmon resonance (LSPR) peaks of AuNPs. The limit of detection concentration (C_LOD ) of this system was 100 μM paraquat. Moreover, among eight cationic salts tested, NaCl was selective to enhance the detection sensitivity of the system, resulting in the reduction of C_LOD to 0.10 μM. This system selectively detected paraquat, but not other tested herbicides (ametryn, atrazine, glyphosate, and 2,4-D-dimethyl ammonium). The paraquat-spiking experiment in kale demonstrated the significant recovery rate of paraquat at 96.0-103.0%, and the relative standard deviations were less than 4%. The developed system was efficient for screening contaminated paraquat in vegetables under unwashed and washed conditions. Three out of five unwashed vegetables had a significant level of paraquat as determined by LSPR values. These results suggested the potential application of this system for a simple screening of contaminated paraquat in vegetables. Simple paraquat-screening system was developed based on the negatively charged gold nanoparticles. The limit of paraquat detection of this system was 0.10 μM. This system was potentially used for a simple screening of contaminated paraquat in vegetables.

Non-thermal technologies: Solution for hazardous pesticides reduction in fruits and vegetables

Pesticide residues in the food above the maximum permissible residual limit (MRL) for safe consumption are a severe concern today. Though unit operations employed in domestic and industrial-scale processing of foods such as high-temperature decontamination and chemical washings degrade the agrochemicals and reduce toxicity, eliminating pesticides from the fresh and raw fruits and vegetables with the retainment of nutritional and organoleptic attributes demand appropriate non-thermal technologies. In this review, the potential of novel technologies like the pulsed electric field, high-pressure processing, irradiation, ozone, ultrasonication, and cold plasma for the reduction of pesticides in fruits and vegetables have been discussed in terms of their mechanism of action, playing around factors, advantages, and limitations. All the reviewed non-thermal technologies exhibited promising effects on pesticide degradation with their unique mechanism of action. Also, these techniques' potential to reduce the pesticides below MRLs and yield nontoxic metabolites in fruits and vegetables were analyzed. However, investigating the impact of the technologies on the nutritional and organoleptic quality profile of the commodities at the processing conditions causing noticeable pesticide reduction and the pathways of degradation reactions of various pesticides with each emerging technology should be studied to enhance the applicability.

Assessment of Health Risk due to Pesticide Residues in Fruits, Vegetables, Soil, and Water

The present study was conducted to assess the contamination and health risk due to the presence of pesticides in fruits and vegetables. A total of six vegetable samples, 3 fruit samples, 7 soil samples, and 6 water samples were collected from three different sampling points. High-performance liquid chromatography using acetonitrile and water solvent system was employed for the quantitative and qualitative analysis. The pesticides having the highest health risk in vegetables were Bifenthrin and Difenoconazole as their health risk index was found to be exceeding the cut off value of 1. Imidacloprid was found in all vegetable samples but had no associated health risk, as all the health risk indices for imidacloprid were below the cut off value of 1. The pesticide Glyphosate detected in only one sample had no health risk associated with it. Health risks in fruits were the highest for Amamectin, Bifenthrin, and Difenoconazole and were crossing the threshold limit of 1. The results reveal the health risk indices of Bifenthrin and Difenoconazole range from 7.8 to 12.46 in vegetables and from 2.704 to 30.454 in fruits, hence, posing a serious threat to human health. Amamectin, although detected in only fruit and water samples, had the highest health risk of 30.454. Imidacloprid and Glyphosate found in every fruit sample had no associated health risk. The results revealed the presence of pesticides in water, soil, fruit, and vegetable samples. Consumers utilizing these vegetables and fruits are under potential health risks due to the presence of pesticides in soil and water. Practical Applications. In this study, an analytical method for detecting pesticides in a variety of environmental matrices including fruits, vegetables, water, and the soil is presented and the health risk associated with the presence of pesticides in a wide range of fruits and vegetables is assessed. It is highly significant because in developing countries agricultural activities contribute majorly toward the total gross domestic product and pesticides are extensively used to control, prevent, devastate, and diminish any harmful pest that destroys crops.