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Among the factors implicated in amphibian global decline, agrochemicals have been gaining increasing attention. In order to evaluate the toxicity of a dimethoate-based insecticide on the early development of an autochthonous amphibian, Rhinella arenarum, continuous and 24 h pulse exposure bioassays were carried out. Lethal and sublethal effects, neurotoxicity and the ecological risk were assessed. Results demonstrate that larvae were more sensitive than embryos with 504 h-LC50 of 12.82 and 16.38 mg L-1, respectively. 24 h pulse experiments showed a high toxicity increment at early embryonic stages, while the sensitivity at later stages was high and constant. Dimethoate caused teratogenesis and several sublethal effects as morphological and behavioral alterations but also disruption in the metamorphic process. About neurotoxicity, dimethoate inhibited the activity of butyrylcholinesterase at 0.5 and 1 mg L-1 exposed larvae. The results obtained in this study as the risk assessment revealed that dimethoate represents a hazard on Rhinella arenarum survival and development but also a potential risk for the continuity of the populations of this species in agroecosystems.

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Dimethoate ([O,O-dimethyl S-(N-methylcarbamoylmethyl) phosphorodithioate]) is an organophosphate insecticide and acaricide widely used for agricultural purposes. Genotoxicity refers to the ability of a chemical agent interact directly to DNA or act indirectly leading to DNA damage by affecting spindle apparatus or enzymes involved in DNA replication, thereby causing mutations. Taking into consideration the importance of genotoxicity induced by dimethoate, the purpose of this manuscript was to provide a mini review regarding genotoxicity induced by dimethoate as a result of oxidative stress. The present study was conducted on studies available in MEDLINE, PUBMED, EMBASE, and Google scholar for all kind of articles (all publications published until May, 2020) using the following key words: dimethoate, omethoate, DNA damage, genetic damage, oxidative stress, genotoxicity, mutation, and mutagenicity. The results showed that many studies were published in the scientific literature; the approach was clearly demonstrated in multiple tissues and organs, but few papers were designed in humans. In summary, new studies within the field are important for better understanding the pathobiological events of genotoxicity on human cells, particularly to explain what cells and/or tissues are more sensitive to genotoxic insult induced by dimethoate.

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Background: The management of empty pesticide containers (EPC) in Bolivia has been recently promoted as a control strategy for dispersed pollution in surface and underground water bodies, as well as in soil. It comprises the rinsing and proper disposal or reuse of clean EPC. However, the rinsing transfers the hazard to water, which must be properly treated before being discharged. Methods: In this study, solar photo-Fenton at low Fe 2+ doses were tested at pilot plant scale in Cochabamba (Bolivia) for the removal of pesticides dimethoate and atrazine in their commercial form, spiked in river water. Results: The results demonstrated that solar photo-Fenton ([H 2O 2] 0 = 200 mg L -1) with Fe 2+ concentrations between 0.5 and 1.5 mg L -1 is an effective method to remove dimethoate and atrazine, at an initial concentration of 10 mg L -1 each. Efficiency increased when increasing Fe 2+ doses, achieving a removal over 99% of both pesticides after a solar irradiation period of 60 minutes (corresponding to an accumulated energy of 4.96 kJ L -1). Conclusions: The presence of high concentrations of natural components of river water, mainly organic and inorganic carbon species, would have contributed to hydroxyl radical scavenging, explaining, together with the low iron dose applied, the high energy (irradiation time) and high hydrogen peroxide concentration required to produce pesticide depletion. Additionally, the relatively low oxidant consumption and mineralization observed leave room for process optimization regarding oxidant and catalyst doses and warrant further studies on its coupling with biological or other post-treatments for the removal of transformation products.

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A simple and rapid method for the determination of dimethoate in water was developed based on the monitoring of the complex formation between bis 5-phenyldipyrrinate of nickel (II) and the herbicide dimethoate. The method showed a short response time (10 s), high selectivity (very low interference from other sulfate and salts), high sensitivity (limit of detection (LOD) 0.45 µM, limit of quantitation (LOQ) of 1.39 µM), and a Kd of 2.4 µM. Stoichiometry experiments showed that complex formation occurred with a 1:1 relation. The method was applied to different environmental water samples such as lagoon, stream, urban, and groundwater samples. The results indicated that independently from the water source, the method exhibited high precision (0.25-2.47% variation coefficient) and accuracy (84.42-115.68% recovery). In addition, the method was also tested using an effluent from a wastewater treatment plant from Mexico; however, the results indicated that the presence of organic matter had a pronounced effect on the detection.

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Dimethoate (D) are among the most commonly used organophosphates insecticides in the world. To evaluate the toxicity of two D formulations were selected as test organisms tadpoles of Rhinella arenarum. This toad species has an extensive neotropical distribution and is easy to handle and acclimate to laboratory conditions. The tadpoles were exposed in an acute assay for 48 h to D soluble concentrates (DSC) and emulsifiable concentrates (DEC). The 48 h-LC50 (95% confidence limits) value of DSC was 57.46 mg L-1 (40.52-81.43) and to DEC was 12.76 mg L-1 (10.39-15.68). These differences in toxicity were statistically significant (p < 0.05). In both formulations, acetylcholinesterase), carboxylesterase, and glutathione-S-transferases enzyme activities varied significantly respect to those of control group (p < 0.05). The DEC formulation was the most toxic. These results would allow the assessment and characterization of potential ecological risks following the application of those formulations.

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BACKGROUND/AIM: The pesticide dimethoate (O-dimethyl-S- Nmethylcarbamoylmethyl phosphorodithioate) is able to induce severe acute toxicity in living organisms. The aim of this study was to evaluate the effects of ultraviolet radiation, alone or combined with exposure to dimethoate, on the rat skin. MATERIALS AND METHODS: A total of 38 Wistar female rats (Rattus norvegicus albinus), were distributed into four groups: A (n=9) control group, B (n=10) exposed to ultraviolet-B radiation (UV-B), C (n=10) exposed to UV-B followed by application of dimethoate (UV-B+AGRO) and group D (n=9) exposed to dimethoate (AGRO). Histological examination of the tissues, as well as immunohistochemistry for cleaved caspase 3, Ki-67 and COX-2 expression were performed to all groups. RESULTS: Animals submitted to UV-B exhibited hyperkeratosis with moderate cell atypia. Regarding exposure to UV-B+AGRO, the animals presented hyperkeratosis and atrophy, whereas in animals exposed to AGRO, only atrophy was noticed. The immunohistochemical results on skin revealed that UVB, AGRO and UVB+AGRO decreased cleaved caspase 3 and Ki-67 expression when compared to the control group (p<0.05). COX-2 expression decreased to UVB or AGRO groups compared to controls (p<0.05). CONCLUSION: UV-B or AGRO exposure is able to induce histopathological changes and altered expression of cleaved caspase-3 and Ki-67 in rat skin, thus being categorized as a risk condition for skin carcinogenesis.

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Sand was studied as a solid support in ultrasound-assisted matrix solid-phase dispersion (UA-MSPD) for the extraction of different pesticide classes, including organophosphates, carbamates, triazoles and pyrethroids from fruits and vegetables, with determination by GC-MS and LC-MS/MS. The performance of sand was compared with that of different types of classic solid supports and alternative natural materials from renewable sources. The best results were obtained using 0.5 g sample, 1 g sand as a solid support, 20 mg activated charcoal and 5 mL ethyl acetate as elution solvent. Recoveries ranged from 55 to 140% with an RSD ≤ 20%. LOQs varied from 0.005 to 0.5 mg kg-1 for all analytes. Thiamethoxam, captan, chlorpyrifos, dimethoate and pyrimethanil were found in strawberry samples at concentrations from 0.01 to 0.06 mg kg-1. Acephate and tebuconazole were found in a tomato sample at concentrations of 0.45 and 0.30 mg kg-1, respectively. The method developed was efficient, simple, cheap, robust, and environmentally friendly.

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This study describes the in-silico design, synthesis, and evaluation of a cross-linked PVA hydrogel (CLPH) for the absorption of organophosphorus pesticide dimethoate from aqueous solutions. The crosslinking effectiveness of 14 dicarboxilic acids was evaluated through in-silico studies using semiempirical quantum mechanical calculations. According to the theoretical studies, the nanopore of PVA cross-linked with malic acid (CLPH-MA) showed the best interaction energy with dimethoate. Later, using all-atom molecular dynamics simulations, three hydrogels with different proportions of PVA:MA (10:2, 10:4, and 10:6) were used to evaluate their interactions with dimethoate. These results showed that the suitable crosslinking degree for improving the affinity for the pesticide was with 20% (W%) of the cross-linker. In the experimental absorption study, the synthesized CLPH-MA20 recovered 100% of dimethoate from aqueous solutions. Therefore, the theoretical data were correlated with the experimental studies. Surface morphology of CLPH-MA20 by Scanning Electron Microscopy (SEM) was analyzed. In conclusion, the ability of CLPH-MA20 to remove dimethoate could be used as a technological alternative for the treatment of contaminated water.

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There is a current tendency to develop and apply environmentally friendly techniques that meet the requirements of green analytical chemistry as an alternative to conventional analytical methods. For toxicity evaluation, these alternatives may be found in bioassays such as Tradescantia. This technique, developed in the 1980s, is highly sensitive to evaluate environmental mutagens, simple and cheap. In this paper, the sensibility of both the Tradescantia micronucleus bioassay (Trad-MCN) and the Tradescantia stamen hair bioassay (Trad-SH) were studied for carbaryl, dimethoate and iprodione, common agricultural and domestic pesticides that are currently used in Chile, which have never been tested with such bioassays. Biomonitor exposures were performed by capillary absorption for each individual pesticide over a wide range of concentrations, from maximum residue limits (trace levels) up to the application dose in agricultural fields. In addition, the organochloride 4,4'-DDE was included but only in the concentration range from 0.01mgL-1 to 1mgL-1, mimicking residue concentrations since it is not a commercial product but, rather, the main breakdown product of the persistent organochloride pesticide 4,4-DDT, whose use was discontinued in Chile in the 1980s. The Trad-MCN bioassay revealed a significant increase in micronucleus frequency at the early tetrads of meiotic pollen mother cells of the biomonitor Tradescantia pallida var. purpurea, induced by 4,4'-DDE (for 1mgL-1), dimethoate (for 40mgL-1, 200mgL-1, 400mg/L-1) and carbaryl (for 889mgL-1). Iprodione did not generate any significant change at the tested concentration. Meanwhile, the Trad-SH bioassay was carried out by analysis of the phenotype variations of the stamen hair cells of the Tradescantia clone KU-20 for the same pesticides and doses. This bioassay was not sufficiently sensitive for toxicity evaluation of most of the pesticides tested, with exception of dimethoate in low doses (2 and 5mg/L-1).

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The importance of fish as a protein source in food is unquestionable, but its role as an indicator of environmental contamination is also very important. This study aimed to analysis the livers of Nile tilapia (Oreochromis niloticus), collected from commercial cold-storages in two municipal districts in the State of Parana, for investigation of contamination by organophosphorus compounds and carbamates. It was collected 30 samples of Nile tilapias (O. niloticus) liver in the cold-storage A and 45 samples in the cold-storage B, totaling 75 samples. At each location were three visits, and at random, collected the samples from July 2006 to May 2007. For extraction and analysis of samples it was used the qualitative methodology of Thin Layer Chromatography (TLC). Patterns of organophosphate and carbamate used in the analysis of the TLC were respectively Dimethoate and Aldicarb. Of the samples tested were found cabarmate in seven samples, one of the samples collected in the cold-storage A and six collected in the cold-storage B. The organophosphate compound was found in fifteen samples from 75 samples, seven of the cold-storage A and eight samples from the cold-storage B.  The results infer the possibility of contamination of the tanks in the creation of farms and the need for constant monitoring for the presence of residues of pesticides in this important food matrix.

A importância dos peixes como fonte protéica na alimentação humana é indiscutível, porém seu papel como indicador de contaminação ambiental também é muito relevante.  O presente trabalho objetivou a análise de fígados de Tilápia do Nilo (Oreochromis niloticus), coletados em frigoríficos comerciais de dois municípios do Estado do Paraná para averiguação de contaminação pelos compostos organofosforados e carbamatos. Coletou-se 30 amostras de fígado de Tilápia do Nilo (O. niloticus) no frigorífico A e 45 amostras no frigorífico B, totalizando 75 amostras analisadas. Em cada local foram realizadas três visitas, e de forma aleatória, coletadas as amostras no período de julho de 2006 a maio de 2007. Para extração e análise das amostras utilizou-se a metodologia qualitativa de Cromatografia em Camada Delgada (CCD). Os padrões de organofosforado e carbamato utilizados na análise de CDD foram respectivamente o Dimetoato e Aldicarb. Nas amostras analisadas foi encontrado o praguicida cabarmato em sete amostras, sendo uma das amostras coletada no frigorífico A e seis coletadas no frigorífico B. O composto organofosforado foi encontrado em quinze amostras das 75 amostras analisadas, sendo sete amostras do frigorífico A e oito das amostras do frigorífico B. Os resultados obtidos inferem na possibilidade da contaminação dos tanques de criação nas pisciculturas e da necessidade de monitoramen

RESUMEN

The importance of fish as a protein source in food is unquestionable, but its role as an indicator of environmental contamination is also very important. This study aimed to analysis the livers of Nile tilapia (Oreochromis niloticus), collected from commercial cold-storages in two municipal districts in the State of Parana, for investigation of contamination by organophosphorus compounds and carbamates. It was collected 30 samples of Nile tilapias (O. niloticus) liver in the cold-storage A and 45 samples in the cold-storage B, totaling 75 samples. At each location were three visits, and at random, collected the samples from July 2006 to May 2007. For extraction and analysis of samples it was used the qualitative methodology of Thin Layer Chromatography (TLC). Patterns of organophosphate and carbamate used in the analysis of the TLC were respectively Dimethoate and Aldicarb. Of the samples tested were found cabarmate in seven samples, one of the samples collected in the cold-storage A and six collected in the cold-storage B. The organophosphate compound was found in fifteen samples from 75 samples, seven of the cold-storage A and eight samples from the cold-storage B.  The results infer the possibility of contamination of the tanks in the creation of farms and the need for constant monitoring for the presence of residues of pesticides in this important food matrix.

A importância dos peixes como fonte protéica na alimentação humana é indiscutível, porém seu papel como indicador de contaminação ambiental também é muito relevante.  O presente trabalho objetivou a análise de fígados de Tilápia do Nilo (Oreochromis niloticus), coletados em frigoríficos comerciais de dois municípios do Estado do Paraná para averiguação de contaminação pelos compostos organofosforados e carbamatos. Coletou-se 30 amostras de fígado de Tilápia do Nilo (O. niloticus) no frigorífico A e 45 amostras no frigorífico B, totalizando 75 amostras analisadas. Em cada local foram realizadas três visitas, e de forma aleatória, coletadas as amostras no período de julho de 2006 a maio de 2007. Para extração e análise das amostras utilizou-se a metodologia qualitativa de Cromatografia em Camada Delgada (CCD). Os padrões de organofosforado e carbamato utilizados na análise de CDD foram respectivamente o Dimetoato e Aldicarb. Nas amostras analisadas foi encontrado o praguicida cabarmato em sete amostras, sendo uma das amostras coletada no frigorífico A e seis coletadas no frigorífico B. O composto organofosforado foi encontrado em quinze amostras das 75 amostras analisadas, sendo sete amostras do frigorífico A e oito das amostras do frigorífico B. Os resultados obtidos inferem na possibilidade da contaminação dos tanques de criação nas pisciculturas e da necessidade de monitoramen