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Environmental Health Insights 2022This study assessed concentrations of pesticide residues in fruits and vegetables from farm-to-fork in Kampala Metropolitan Area, Uganda. A total of 160 samples of fruit...
This study assessed concentrations of pesticide residues in fruits and vegetables from farm-to-fork in Kampala Metropolitan Area, Uganda. A total of 160 samples of fruit and vegetables collected from farms, markets, streets, restaurants and homes were analysed using liquid chromatography-tandem mass spectrometry; and Gas Chromatograph-Mass Spectrometer for dithiocarbamates. Multiple pesticide residues were detected in majority of the samples (95.6%). The proportions of the most frequently detected pesticides residue classes were organophosphates (91.3%), carbamates (67.5%), pyrethroids (60.0%) dithiocarbamates (48.1%) and neonicotinoids (42.5%). Among organophosphates, propotamophos, acephate, fonofos, monocrotophos and dichlorvos were the most detected active ingredients; aminocarb, methomyl and pirimicarb were the commonly detected carbamates; while imidacloprid, a neonicotinoid and lambda-cyhalothrin, pyrethroid were also highly detected. Twenty-seven pesticide were tested at all stages, of which the concentrations either decreased or increased along the chain. Multiple pesticide residues occurred in commonly consumed fruit and vegetables with decreasing or increasing concentrations from farm-to-fork.
PubMed: 35846167
DOI: 10.1177/11786302221111866 -
NanoImpact Jan 2022During emission, TiO nanoparticles (NPs) might meet various chemicals, including metal ions and organic compounds in aquatic environments (e.g., surface water,...
During emission, TiO nanoparticles (NPs) might meet various chemicals, including metal ions and organic compounds in aquatic environments (e.g., surface water, sediments). At environmentally safe concentrations, combinations of both TiO NPs and those chemicals might cause cocktail effects (i.e., mixture toxicity) to aquatic organisms. Previous models such as concentration addition and independent action require dose-response curves of single components in the mixtures to predict the mixture toxicity. Structure-activity relationship (QSAR) models might predict the toxicity of nano-mixtures without dose-response curves of single components in the mixtures. However, current quantitative structure-activity relationship (QSAR) models are mainly focused on predicting cytotoxicity (i.e., cell viability) of heterogeneous metallic TiO nanoparticles (NPs) or mixtures of TiO NPs and four metal ions (Cu, Cd, Ni and Zn). To minimize the experimental cost of nano-mixture risk assessment, in this study, we developed novel nano-mixture QSAR models to predict i) EC of 76 nano-mixtures containing TiO NPs and one of eight inorganic/organic compounds (i.e., AgNO, Cd(NO), Cu(NO), CuSO, NaHAsO, NaAsO, Benzylparaben and Benzophenone-3), to Daphnia magna(D. magna), and ii) immobilization of D. magna exposed to one of 98 mixtures containing TiO NPs and one of eleven inorganic/organic compounds (i.e., AgNO, Cd(NO), Cu(NO), CuSO, NaHAsO, NaAsO, Benzylparaben Benzophenone-3, Pirimicarb, Pentabromodiphenyl Ether and Triton X-100). The nano-mixture QSAR models were developed with mixture descriptors (D) combing quantum descriptors of mixture components (e.g., TiO NPs and its partners) by using different machine learning techniques (i.e., random forest, neural network, support vector machine, and multiple linear regression). Nano-mixture QSAR models built with the random forest algorithm and proposed mixture descriptors exhibited good performance for predicting logEC (Adj.R = 0.955 ± 0.003, RMSE = 0.016 ± 0.002, and MAE = 0.008 ± 0.001) and immobilization (Adj.R = 0.888 ± 0.011, RMSE = 11.327 ± 0.730, and MAE = 5.933 ± 0.442). The models developed in this study were implemented in a user-friendly application for assessing the aquatic toxicity of TiO based nano-mixtures.
Topics: Animals; Cadmium; Daphnia; Organic Chemicals; Quantitative Structure-Activity Relationship; Titanium; Water Pollutants, Chemical
PubMed: 35559889
DOI: 10.1016/j.impact.2022.100383 -
Chemosphere Mar 2023Due to their extensive use and high biological activity, insecticides largely contribute to loss of biodiversity and environmental pollution. The regulation of...
Due to their extensive use and high biological activity, insecticides largely contribute to loss of biodiversity and environmental pollution. The regulation of insecticides by authorities is mainly focused on lethal concentrations. However, sub-lethal effects such as alterations in behavior and neurodevelopment can significantly affect the fitness of individual fish and their population dynamics and therefore deserve consideration. Moreover, it is important to understand the impact of exposure timing during development, about which there is currently a lack of relevant knowledge. Here, we investigated whether there are periods during neurodevelopment of fish, which are particularly vulnerable to insecticide exposure. Therefore, we exposed zebrafish embryos to six different insecticides with cholinergic mode of action for 24 h during different periods of neurodevelopment and measured locomotor output using an age-matched behavior assay. We used the organophosphates diazinon and dimethoate, the carbamates pirimicarb and methomyl as well as the neonicotinoids thiacloprid and imidacloprid because they are abundant in the environment and cholinergic signaling plays a major role during key processes of neurodevelopment. We found that early embryonic motor behaviors, as measured by spontaneous tail coiling, increased upon exposure to most insecticides, while later movements, measured through touch-evoked response and a light-dark transition assay, rather decreased for the same insecticides and exposure duration. Moreover, the observed effects were more pronounced when exposure windows were temporally closer to the performing of the respective behavioral assay. However, the measured behavioral effects recovered after a short period, indicating that none of the exposure windows chosen here are particularly critical, but rather that insecticides acutely interfere with neuronal function at all stages as long as they are present. Overall, our results contribute to a better understanding of risks posed by cholinergic insecticides to fish and provide an important basis for the development of safe regulations to improve environmental health.
Topics: Animals; Insecticides; Zebrafish; Diazinon; Cholinergic Agents; Phenotype
PubMed: 36646183
DOI: 10.1016/j.chemosphere.2023.137874 -
Journal of Chromatography. A Oct 2021The low-cost set-up is based on the flexible microfluidic breadboard approach. To avoid the use of electrically driven devices at the high voltage injection end of the...
The low-cost set-up is based on the flexible microfluidic breadboard approach. To avoid the use of electrically driven devices at the high voltage injection end of the capillary pneumatically actuated pumps and valves are employed. It is coupled to the mass spectrometer with a sheathless electrospray obtained in an electrodeless interface configuration. This simplification is achieved by carrying out the analysis in two distinct steps, firstly the separation without the formation of an electrospray, and secondly detection in which the electrospray is created while pumping out the content of the capillary. The performance of the instrument was tested by analysing three benzalkonium ions and the four pesticides pyrifenox, pirimicarb, cyprodinil and pyrimethanil. Detection limits between 0.36 and 0.76 µM and peak reproducibilities between 5.2% and 6.6% (50 µM standards) were obtained for the latter.
Topics: Electrophoresis, Capillary; Pesticides; Reference Standards; Spectrometry, Mass, Electrospray Ionization
PubMed: 34537661
DOI: 10.1016/j.chroma.2021.462533 -
International Journal of Molecular... Mar 2022Glutathione transferases (GSTs; EC 2.5.1.18) form a group of multifunctional enzymes that are involved in phase II of the cellular detoxification mechanism and are...
Glutathione transferases (GSTs; EC 2.5.1.18) form a group of multifunctional enzymes that are involved in phase II of the cellular detoxification mechanism and are associated with increased susceptibility to cancer development and resistance to anticancer drugs. The present study aims to evaluate the ligandability of the human GSTM1-1 isoenzyme (hGSTM1-1) using a broad range of structurally diverse pesticides as probes. The results revealed that hGSTM1-1, compared to other classes of GSTs, displays limited ligandability and ligand-binding promiscuity, as revealed by kinetic inhibition studies. Among all tested pesticides, the carbamate insecticide pirimicarb was identified as the strongest inhibitor towards hGSTM1-1. Kinetic inhibition analysis showed that pirimicarb behaved as a mixed-type inhibitor toward glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB). To shine a light on the restricted hGSTM1-1 ligand-binding promiscuity, the ligand-free crystal structure of hGSTM1-1 was determined by X-ray crystallography at 1.59 Å-resolution. Comparative analysis of ligand-free structure with the available ligand-bound structures allowed for the study of the enzyme's plasticity and the induced-fit mechanism operated by hGSTM1-1. The results revealed important structural features of the H-site that contribute to xenobiotic-ligand binding and specificity. It was concluded that hGSTM1-1 interacts preferentially with one-ring aromatic compounds that bind at a discrete site which partially overlaps with the xenobiotic substrate binding site (H-site). The results of the study form a basis for the rational design of new drugs targeting hGSTM1-1.
Topics: Binding Sites; Crystallography, X-Ray; Glutathione; Glutathione Transferase; Humans; Kinetics; Ligands; Pesticides; Xenobiotics
PubMed: 35408962
DOI: 10.3390/ijms23073606 -
Journal of Insect Science (Online) 2013The aphids Sitobion avenae (Fabricius) and Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphidiae) are serious pests on grain crops and usually coexist on late period of... (Comparative Study)
Comparative Study
The aphids Sitobion avenae (Fabricius) and Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphidiae) are serious pests on grain crops and usually coexist on late period of wheat growth in China. Bioassays showed that R. padi was more susceptible than S. avenae to pirimicarb that is used for wheat aphid control, and the determination of acetylcholinesterase (AChE, EC 3.1.1.7) sensitivity showed that the sensitivity of AChE to pirimicarb was significantly higher in R. padi than in S. avenae ( Lu and Gao 2009 ). AChE is the target enzyme of the carbamates, including pirimicarb, hence, to understand the mechanism responsible for the tolerance difference to carbamate insecticides of S. avenae and R. padi, we purified AChE from both aphid species using procainamide affinity column and characterized the AChE. The purification factor and yield from S. avenae (234.7-fold and 92.9%) were far higher than that from R. padi 17.3-fold and 13.9%. The results of substrate and inhibitor specificities of purified enzyme from both S. avenae and R. padi indicated that the purified enzyme was a typical AChE. The crude AChE extract from S. avenae was 5.4-, 4.3- and 8.1-fold less sensitive to inhibition by pirimicarb, methomyl and thiodicarb, respectively, than that from R. padi, whereas for the purified AChE, S. avenae was only 1.6-, 1.3- and 1.7-fold less sensitive to inhibition by pirimicarb, methomyl and thiodicarb, respectively, than R. padi. This suggests that eserine and BW284C51 may bind with other proteins, such as carboxylesterase, in the crude extract to reduce their inhibition against AChE. These results are useful for planning the chemical control of aphids on wheat.
Topics: Acetylcholinesterase; Animals; Aphids; Kinetics; Substrate Specificity
PubMed: 23879406
DOI: 10.1673/031.013.0901 -
Nanomaterials (Basel, Switzerland) Aug 2022A three-steps sol-gel method was used to obtain a CuO/SnO/WO heterostructure powder, deposited as film by spray pyrolysis. The porous morphology of the final...
A three-steps sol-gel method was used to obtain a CuO/SnO/WO heterostructure powder, deposited as film by spray pyrolysis. The porous morphology of the final heterostructure was constructed starting with fiber-like WO acting as substrate for SnO development. The SnO/WO sample provide nucleation and grew sites for CuO formation. Diffraction evaluation indicated that all samples contained crystalline structures with crystallite size varying from 42.4 Å (CuO) to 81.8 Å (WO). Elemental analysis confirmed that the samples were homogeneous in composition and had an oxygen excess due to the annealing treatments. Photocatalytic properties were tested in the presence of three pesticides-pirimicarb, S-metolachlor (S-MCh), and metalaxyl (MET)-chosen based on their resilience and toxicity. The photocatalytic activity of the CuO/SnO/WO heterostructure was compared with WO, SnO, CuO, CuO/SnO, CuO/WO, and SnO/WO samples. The results indicated that the three-component heterostructure had the highest photocatalytic efficiency toward all pesticides. The highest photocatalytic efficiency was obtained toward S-MCh (86%) using a CuO/SnO/WO sample and the lowest correspond to MET (8.2%) removal using a CuO monocomponent sample. TOC analysis indicated that not all the removal efficiency could be attributed to mineralization, and by-product formation is possible. CuO/SnO/WO is able to induce 81.3% mineralization of S-MCh, while CuO exhibited 5.7% mineralization of S-MCh. The three-run cyclic tests showed that CuO/SnO/WO, WO, and SnO/WO exhibited good photocatalytic stability without requiring additional procedures. The photocatalytic mechanism corresponds to a Z-scheme charge transfer based on a three-component structure, where CuO exhibits reduction potential responsible for O production and WO has oxidation potential responsible for HO· generation.
PubMed: 35957078
DOI: 10.3390/nano12152648 -
Foods (Basel, Switzerland) Aug 2023In this study, a new approach to pesticide permeation through the apple peel into the pulp is discussed. The tested compounds can be classified, based on mode of action,...
In this study, a new approach to pesticide permeation through the apple peel into the pulp is discussed. The tested compounds can be classified, based on mode of action, as systemic (boscalid, cyprodinil, pirimicarb, propiconazole and tebuconazole) or contact (captan, cypermethrin and fludioxonil) pesticides. The barrier effect was assessed using a Franz flow-type vertical diffusion cell system. A residue analysis was performed using a modified quick, easy, cheap, efficient, rugged and safe (QuEChERS) extraction method coupled to gas chromatography with tandem mass spectrometry (GC-MS/MS). The limits of detection (LODs) ranged between 2.6 µg kg (pirimicarb) and 17 µg kg (captan), with the coefficient of variability (CV) lower than 6%, while recoveries ranged from 85% (boscalid) to 112% (captan) at 0.1 and 1 mg kg spiked levels. The highest peel penetration was observed for pirimicarb, captan and cyprodinil, with cumulative permeations of 90, 19 and 17 µg cm, respectively. The total absorption was in the range from 0.32% (tebuconazole) to 32% (pirimicarb). Only cypermethrin was not quantitatively detected in the pulp, and its use can be recommended in crop protection techniques. The obtained results indicate that molecular weight, octanol-water partition coefficient and water solubility are important parameters determining the process of pesticide absorption.
PubMed: 37685153
DOI: 10.3390/foods12173220 -
Occupational and Environmental Medicine Nov 2000The dominant route of occupational exposure to pesticides in horticulture is dermal. However, preventive measures are seldom used when handling plant cultures recently...
OBJECTIVES
The dominant route of occupational exposure to pesticides in horticulture is dermal. However, preventive measures are seldom used when handling plant cultures recently treated with pesticides, thus causing significant dermal exposure and potential absorption. Assessment of exposure often depends on biological monitoring of blood or urine samples. The skin often acts as a temporary reservoir for chemicals before absorption. Failure to consider the lag time between dermal exposure and appearance of pesticide or metabolites in the general circulation may lead to false conclusions about assessment of exposure.
METHODS
In an experimental model in which in vitro static diffusion cells were mounted with human skin, dermal penetration of three extensively used pesticides (methiocarb, paclobutrazol, pirimicarb) was evaluated.
RESULTS
Pirimicarb and paclobutrazol had comparable rates of dermal penetration and lag times of around 18 hours. Methiocarb had a considerably shorter lag time. Dermal penetration continued for extended periods after exposure had ended.
CONCLUSIONS
With lag times sometimes considerably longer than a normal working day, biological monitoring at the end of exposure may seriously underestimate the actual exposure. There may be implications for regulatory guidelines, which often require only 24 hour observation periods.
Topics: Adult; Aged; Aged, 80 and over; Female; Humans; In Vitro Techniques; Insecticides; Methiocarb; Middle Aged; Occupational Exposure; Permeability; Plant Growth Regulators; Skin; Skin Absorption; Time Factors; Triazoles
PubMed: 11024196
DOI: 10.1136/oem.57.11.734 -
Insects Sep 2023The invasive apricot aphid ( Matsumura) is an important pest of apricot trees ( L.). In the presented study, laboratory bioassays using treated leaf disks of apricot...
The invasive apricot aphid ( Matsumura) is an important pest of apricot trees ( L.). In the presented study, laboratory bioassays using treated leaf disks of apricot were conducted to test the efficacy of twelve insecticides according to the maximum field dose. Additionally, dose-response curves were established for selected insecticides, and the effects on colony development were evaluated. Furthermore, a field trial was conducted to investigate the effectiveness of commonly used insecticides in apricot cultivation. The dose-response curves showed LC values ranging from 0.08 mg/L for flupyradifurone, 0.15 mg/L for acetamiprid, 0.70 mg/L for etofenprox, 1.89 mg/L for sulfoxaflor, 2.64 mg/L for pirimicarb, 3.97 mg/L for deltamethrin, up to 6.79 mg/L for tau-fluvalinate. These aforementioned insecticides resulted in mortality rates ranging from 95 to 100% at the field dose. Azadirachtin, flonicamid, and pyrethrins showed mortality rates of 27 to 45%. Spirotetramat reduced the colony development and decreased the number of infested shoots by 86%. Spinosad, which is not recommended against aphids, showed minimal impact; reducing the number of exuviae in nymphs in the colony development bioassay. It can be concluded that the majority of the tested insecticides are effective against .
PubMed: 37754715
DOI: 10.3390/insects14090746