971 resultados para  Toxicidade 


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Guava (Psidium guajava L.) is a plant often employed in popular medicine. Recently several studies have alerted about the toxicity of substances present in medicinal plants, which can pose risks to the human health. In this sense, the present work aimed to investigate the phytotoxic, cytotoxic and genotoxic action of three guava varieties - Paluma, Pedro Sato and Roxa (purple) - on the plant test system Lactuca sativa L. Thus, macro- and microscopic evaluations were carried out for five infusion concentrations (2.5, 5.0, 10.0, 20.0 and 40.0 g.L-1) prepared from each variety. Distilled water was used as negative control. Chromatographic and spectroscopic analysis by HPLC-PAD indicated that the chemical composition of the infusion of Roxa is different than that of the infusions of the varieties Paluma and Pedro Sato. It was observed that seed germination and root growth in L. sativa exposed to infusions decreased with increasing infusion concentration, regardless of the tested cultivar. For the mitotic index, no statistical differences were observed. On the other hand, a significant increase in the frequency of cell cycle alterations was verified, especially for the highest concentrations tested. The cytogenotoxic was significant. Therefore, guava should not be used indiscriminately in popular medicine.

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Pós-graduação em Química - IBILCE

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Pós-graduação em Engenharia Mecânica - FEG

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Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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the aims of this study were to determine imazapyr efficacy for floating macrophyte control and ecotoxicology for non-target organisms. For the floating macrophyte control efficacy tests were used the doses of 0,5; 1,0; 2,0; 2,5; 3,0; 3,5 and 4,0 L ha(-1) and a control with 10 replicates. The acute toxicology for non-target organisms was estimated by lethal concentration 50% (LC50 and EC50). The floating macrophyte control efficacy was over 90%. Imazapyr was classified as moderately toxic for the following biomarkers: L. minor, H. eques, B. rerio, P. caudimaculatus, P. canaliculata, and P. mesopotamicus and lightly toxic for A. caroliniana. Thus, imazapyr herbicide is a tool with great potential to be used on floating macrophyte control (E. crassipes, P. stratiotes e S. molesta) in Brazil and this practice can be evaluated by the use of application biomarkers.

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The aims of this research were to evaluate the acute toxicity (LC/EC50) and the environmental risk of toltrazuril (TOL) and florfenicol (FFC) for plant Lemna minor, snail Pomacea canalicuta, fish Piaractus mesopotamicus and Hyphessobrycon eques and the microcrustacean Daphnia magna. The organisms were acclimated in room bioassay with controlled temperature according to standard to each one. They were exposed at nominal concentrations in static system. For environmental risk (RQ) was used the estimated environmental concentration (EEC) that is the dosage indicate to treatment and the lethal or effective concentration (LC/CE50) from each drug in acute exposure. FFC showed LC50;7d of 97.03 mg L-1 for L. minor; >100.0 mg L-1 for P. mesopotamicus and H. eques and EC50;48h > 100.0 mg L-1 for P. canaliculata and D. magna, and it was classified low risk (RQ = 0.01) for all bioindicators. TOL howed LC50;7d >100.0 mg L-1 for L. minor, 3.72 mg L-1 for P. mesopotamicus; 6.22 mg L-1 for H. eques and CE50;48h of 7.59 mg L-1 for P. canaliculata and 18.57 mg L-1 for D. magna, and it was classified low risk (RQ = 0.01) for L. minor and high risk for P. mesopotamicus (RQ = 2.68), H. eques (RQ = 6.22), P. canaliculata (RQ = 1.31) and D. magna (RQ = 0.53). Lemna minor was the bioindicator indicating of FFC toxicity and H. eques, bioindicator of the TOL. FFC is safety however and the use of TOL necessaries cautions to treat the wastewater before discard on the environment.

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Spills can ocurr during oil productive chain and contaminate various environments due to the toxicity of monoaromatics hidrocarbons. Toluene stands out for being agressive to the nervous sistem and teratogenic, with high mobility and solubility in water, which facilitates environmental impact. Studies show that fungi are potential aromatic compounds assimilators, encouraging new researches about its use on the recovery of contaminated sites. This study aimed to select and characterize fungus with potential for biorremediation of toluene. 50 fungi were selected of the Collection of Microorganisms of Interest for Oil Gas and Biofuels, of UNESP Rio Claro, all of which were isolated from sites contaminated with monoaromatic hydrocarbons. Two trials were realized to select the microorganism with greater potential. The first test evaluated fungal growth under toluene saturated atmosphere. 24 fungi were chosen because its greater biomass production to participate in the next trial, the degradation in plates test, where the blue redox agente, DCPIP, indicates the degradation reaction, turning colorless. From this teste was possible to select one isolate which showed higher growth and stronger medium discoloration as the microorganism with the greatest potential to assimilate toluene. The Trichoderma cf. koningii had its potential evaluated through gas cromatography. The experiment proved the efficiency of the methodology, with positives results from the method validation and the effectiveness demonstrated of the LA-PHA-PACK bottles to prevent the volatilization of toluene during the 21 days of experiment. Being reliable its use for monitoring toluene decay associating it with degradation. This results are important because there aren't many methodologies and vials efficient to the purpose of this work. In the present study the degradation rates demonstrated no significant decay of the concentration of hydrocarbon. That may be related to the...

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Sabendo-se do potencial de toxicidade do mercúrio, mais especificamente de sua forma orgânica, o metilmercúrio (MeHg), faz-se necessária a busca por métodos analíticos eficientes e precisos para a determinação e especiação do metal. A técnica de difusão por gradiente em filmes finos (DGT) já vem sendo utilizada para tal fim de maneira eficiente tendo apresentado resultados satisfatórios em diversos estudos. Porém, a utilização de ligantes alternativos aos convencionais, que tornem a aplicação da técnica menos custosa em termos laborais e financeiros, faz-se importante para um monitoramento constante e eficiente do metilmercúrio no ambiente. No presente trabalho buscou-se avaliar o potencial da levedura Saccharomyces cerevisiae imobilizada em agarose em combinação com a poliacrilamida como agente difusivo para determinação seletiva de MeHg. Os resultados demonstraram-se positivo, com um coeficiente de difusão médio de 7,03 ± 0,77 x 10-6 cm2 s-1. Os resultados demonstraram também baixa influencia do pH, força iônica e outros íons na retenção do analito pelos dispositivos. As recuperações de Hg2+ demonstraram-se insatisfatórios, evidenciando a seletividade dos dispositivos

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O cádmio (Cd) é um metal tóxico considerado não essencial nos organismos. As principais vias de exposição e contaminação pelo metal vem de atividades antrópicas. Há evidências suficientes de que o Cd e seus compostos são carcinogênicos, tendo como principais órgãos afetados: rins, ossos, pulmões e próstata. No citosol o Cd pode estar na forma livre (genericamente, como complexos inorgânicos lábeis) ou ligado com metalotioneinas (genericamente, ligado a proteínas). A relação do Cd (livre ou lábil) com patogenicidades faz com que seja de grande importância a elaboração de métodos para especiação do metal. Este projeto teve como objetivo propor um método para determinação seletiva do Cd lábil em baixas concentrações (μg L-1) utilizando um substrato biológico como material sorvente (S. cerevisiae). A utilização da S. cerevisiae tem sido recomendada para pré-concentração e especiação de metais em água e materiais biológicos. No entanto, estes métodos não proporcionam limites de detecção (LD) suficientes para determinação seletiva de Cd lábil em algumas situações, particularmente quando se procura estabelecer uma relação desta fração do metal com algumas patogenicidades. O método desenvolvido consiste, basicamente, em amostrar o Cd lábil no citosol pela levedura. Depois de digestão ácida em sistema pressurizado (micro-ondas) e/ou da eluição, a espécie retida pela levedura foi determinada por ICP-MS. O uso da ICP-MS permitiu atingir LD suficientes para detecção de Cd, sendo para retenção 0,004 μg L-1 e para a eluição 0,003 μg L-1