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Evidences for charge-transfer complex formation in the benzene adsorption on sulfated TiO2-a resonance Raman spectroscopy investigation

NODA, L. K.; ROSALES, R.; GONCALVES, N. S.; SALA, O.
Fonte: JOHN WILEY & SONS LTD Publicador: JOHN WILEY & SONS LTD
Tipo: Artigo de Revista Científica
ENG
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Benzene adsorbed on highly acidic sulfated TiO2 (S-TiO2) shows an intriguing resonance Raman (RR) effect, with excitation in the blue-violet region. There are very interesting spectral features: the preferential enhancement of the e(2g) mode (1595 cm(-1)) in relation to the a(1g) mode (ring-breathing mode at 995 cm(-1)) and the appearance of bands at 1565 and 1514 cm(-1). The band at 1565 cm(-1) is probably one of the components of the e(2g) split band, originally a doubly degenerate mode (8a, 8b) in neat benzene, and the band at 1514 cm(-1) is assigned to the 19a mode, an inactive mode in neat benzene. These facts indicate a lowering of symmetry in adsorbed benzene, which may be caused by a strong interaction between S-TiO2 and the benzene molecule with formation of a benzene to Ti (IV) charge transfer (CT) complex or by the formation of a benzene radical cation species. However, the RR spectra of the adsorbed benzene cannot be assigned to the benzene radical cation because the observed wavenumber of the ring-breathing mode does not have the value expected for this species. Moreover, it was found by ESR measurements that the amount of radicals was very low, and so it was concluded that a CT complex is the species that originates the RR spectra. The most favorable intensification of the band at 1595 cm(-1) in the RR spectra of benzene/S-TiO2 at higher excitation energy corroborates this hypothesis...

Prevenção da exposição ao benzeno no Brasil; Prevention against exposure to benzene im Brazil

Costa, Danilo Fernandes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/06/2009 PT
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A prevenção da exposição ao benzeno têm sido uma preocupação em diversos países desde o final do século XIX. Neste estudo foi feita uma recuperação do percurso histórico da utilização industrial do benzeno no Brasil, da produção técnico-científica sobre a saúde dos trabalhadores a ele expostos e dos conflitos sociais que tiveram maior repercussão, identificando com isto os elementos presentes nestes processos capazes de dar resposta à indagação central da investigação: se as restrições legais à exposição ao benzeno influenciaram positivamente na prevenção da exposição a esta substância no país. A experiência internacional serviu como contraponto, pois muitas situações que ocorreram nos países centrais se repetiram posteriormente nos países de industrialização tardia. Os resultados mostraram que, no Brasil e no mundo, pode-se dividir em quatro períodos a exposição a benzeno. Um período inicial, com pouco uso e quase sem notícias de casos. Um segundo momento em que a utilização aumenta de forma significativa e as exposições se tornam importantes: na experiência internacional este é um momento de ocorrência de muitos casos de Aplasia de Medula; no Brasil, apesar das exposições também altas...

Determinação eletroquímica de fenóis após processo de degradação de benzeno usando sensor à base de nanotubos de carbono-ftalocianina de cobalto; Electrochemical determination of phenols after the process of degradation of benzene using sensor based on carbon nanotubes-cobalt phtalocyanine

Santos, Deodato Peixoto dos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/02/2012 PT
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Episódios de contaminação envolvendo hidrocarbonetos de petróleo são relatados com bastante freqüência, principalmente em função dos acidentes envolvendo transporte e estocagem de combustíveis, dentre os quais se destacam o benzeno, tolueno, etilbenzeno e xileno (BTEX). Assim, não é surpreendente o grande número de trabalhos, atualmente disponíveis, relacionados à remediação de águas subterrâneas. Entretanto, é conhecido que a total mineralização de benzeno, na maioria das tecnologias utilizadas para remediação de solos e águas subterrâneas, não ocorre totalmente podendo formar compostos fenólicos altamente tóxicos. Por este motivo, este trabalho teve por finalidade a análise dos subprodutos formados a partir da degradação do benzeno, que são eles: hidroquinona, resorcinol, catecol, fenol, p-benzoquinona. Para este propósito, os compostos fenólicos formados foram medidos utilizando um eletrodo de carbono vítreo modificado com filme de nanotubos de carbono e ftalocianinas metalicas. Os compostos fenólicos também foram analisados por cromatografia liquida de alta eficiência com detector espectrofotométrico, espectrometria no UV/Visível. Os sensores eletroquímicos propostos mostraram-se altamente eletrocatalíticos e sensíveis na determinação dos derivados da oxidação do benzeno...

Avaliação citogenética e molecular de trabalhadores intoxicados pelo benzeno; Cytogenetic and molecular evaluation of workers poisoned by benzene

Santos, Deise Nascimento Crispim dos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/11/2012 PT
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O benzeno é um hidrocarboneto aromático produzido pela combustão de produtos naturais. A exposição ocupacional ao benzeno é caracterizada por ambientes industriais que o empregam em seus processos produtivos. Nos laboratórios de indústria do petróleo ele é utilizado em forma pura para análise, e está presente como contaminante em derivados, como gasolina, hexano, querosene, tolueno, entre outros. No Brasil o valor recomendado pela legislação como limite de exposição ambiental ao benzeno é de 1ppm. O câncer hematológico é considerado um dos principais fatores de risco para a saúde dos trabalhadores expostos ao benzeno e a utilização de biomarcadores no monitoramento destes profissionais tem sido sugerida em diferentes países. O presente trabalho teve como objetivo avaliar diferentes biomarcadores em sangue periférico de trabalhadores homens, cronicamente expostos ao benzeno em refinarias e siderurgia (18 deles com diagnóstico de intoxicação), que estavam afastados de suas funções por períodos que variaram de cinco meses a 27 anos, com idade média de 46,8 ± 9,33 anos comparado com um grupo controle composto também de 20 homens, selecionados em Bancos de Sangue (idade média de 45,7 ± 8,00 anos), com diferentes ocupações não correlacionadas ao agente em estudo. Em ambos os grupos foram realizados hemograma completo...

Determinação do ácido trans, trans-mucônico urinário por chromatografia líquida de alta eficiência visando a biomonitorização de trabalhadores expostos ao benzeno; Determination of trans, trans-muconic acid by liquid chromatografia high efficiency aiming biomonitoring of workers exposed to benzene

Martins, Isarita
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/12/1999 PT
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O benzeno é um solvente comprovadamente cancerígeno e, para substâncias com tal característica, não há limites de exposição considerados seguros. Em vista disso, as discussões internacionais e nacionais visam a diminuir, cada vez mais, os níveis de exposição ocupacional permitidos. O ácido trans, trans-mucônico (ttAM) , um produto de biotransformação do benzeno, tem sido preconizado como um bioindicador sensível da exposição ao solvente. Este trabalho foi desenvolvido com o propósito de validar método capaz de detectar o ttAM em urina de indivíduos expostos ao benzeno, bem com estabelecer o melhor período de coleta das amostras. A técnica escolhida foi a cromatografia líquida de alta eficiência (CLAE) com coluna de fase-reversa, Lichrosorb RP 18, e detector de ultra-violeta. O método mostrou-se linear entre 0,2 a 5,0 mg/L (r2 = 0,9943). Os limites de detecção e de quantificação obtidos foram, respectivamente, 0,1 e 0,2 mg/L. A porcentagem de recuperação absoluta média foi de 77,1% e de inexatidão de 27,9%. Os coeficientes de variação médios foram, para a precisão intra-ensaio 7,7 % e, para a interensaio 10,6%. O analito permaneceu estável na matriz por um período de 6 semanas para a concentração de 0...

Desenvolvimento de metodologia analítica para a determinação de indicador biológico de exposição ao benzeno; Development of analytical methodology for the determination of biological marker of exposure to benzene

Coutrim, Mauricio Xavier
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 08/10/1998 PT
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Os limites de exposição ocupacional ao benzeno, um agente carcinogênico, vêm diminuindo drasticamente nos últimos anos. Por outro lado, a concentração de benzeno em ambientes não ocupacionais tem aumentado devido à emissão biogênica e antropogênica, como exaustão de motores a gasolina e fumaça de cigarro. Indicadores Biológicos de Exposição (IBE) são utilizados como ferramentas importantes na avaliação da exposição humana ao benzeno. Com a diminuição dos limites de exposição, se faz necessário o desenvolvimento de metodologias analíticas com sensibilidade adequada para a determinação de IBE em fluidos biológicos que se correlacionem com baixas concentrações de benzeno absorvido pelo organismo. A utilização do fenol urinário como IBE ao benzeno, embora reconhecida mundialmente, tem a desvantagem de não apresentar boa correlação com a concentração de benzeno ambiental quando esta é menor do que 10 ppm (32 mg/m3). Os ácidos trans,trans-mucônico e S-fenilmercaptúrico, metabólitos do benzeno encontrados na urina, estão entre os compostos mais estudados como IBE ao benzeno. Neste trabalho, o ácido trans,trans-mucônico foi determinado na urina de indivíduos expostos ao benzeno utilizando as técnicas de Eletroforese Capilar (CE) e HPLC...

In vivo CYP2E1 phenotyping as a new potential biomarker of occupational and experimental exposure to benzene

Piccoli, P.; Carrieri, M.; Padovano, L.; Di Mare, M.; Bartolucci, G. B.; Fracasso, M. E.; Lepera, J. S.; Manno, M.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 29-33
ENG
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Assessing CYP2E1 phenotype in vivo may be important to predict individual susceptibility to those chemicals, including benzene, which are metabolically activated by this isoenzyme. Chlorzoxazone (CHZ), a specific CYP2E1 substrate, is readily hydroxylated to 6-OH-chlorzoxazone (6-OH-CHZ) by liver CYP2E1 and the metabolic ratio 6-OH-CHZ/CHZ in serum (MR) is a specific and sensitive biomarker of CYP2E1 activity in vivo in humans. We used this MR as a potential biomarker of effect in benzene-treated rats and, also, in humans occupationally exposed to low levels of benzene. Male Sprague-Dawley rats (375-400 g b.w.) were treated i.p. for 3 days with either a 0.5 ml solution of benzene (5 mmol/kg b.w.) in corn oil, or 0.5 ml corn oil alone. Twenty-four hours after the last injection, a polyethylene glycol (PEG) solution of CHZ (20 mg/kg b.w.) was injected i.p. in both treated and control animals. After 2, 5.10,15, 20,30,45, 60, 90, 120, 180, and 240 min from injection, 0.2 ml blood was taken from the tip tail and stored at -20 degrees C until analysis. A modified reverse phase HPLC method using a 5 mu m Ultrasphere C18 column equipped with a direct-connection ODS guard column, was used to measure CHZ and its metabolite 6-OH-CHZ in serum. No statistically significant difference in the MR was observed...

Assessment of the Removal Capacity, Tolerance, and Anatomical Adaptation of Different Plant Species to Benzene Contamination

Campos, Valquiria de; Souto, L. S.; Medeiros, Thales Augusto de Miranda; Toledo, S. P.; Sayeg, I. J.; Ramos, R. L.; Shinzato, M. C.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 12
ENG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 12/05595-0; Processo FAPESP: 12/05982-3; Processo FAPESP: 12/08337-1; Processo FAPESP: 12/24832-2; The medium most directly affected by anthropic contamination is soil and, hence, groundwater (saturated and unsaturated zones). In the phytoremediation process, the direct absorption of soil contaminants through the roots is a surprising pollutant removal mechanism. Plants can act as a natural filter of shallow groundwater contamination, controlling and reducing the vertical percolation of contaminants into the soil, and after reaching the level of the water table, the roots can absorb contaminants dissolved in the water, thus reducing the size of the plume and protecting receptor sites (water supply wells, rivers, lakes) from possible contamination. In the first phase of the research, assays were performed to evaluate the tolerance of plant species to the direct injection of a benzene solution into the roots. Subsequent experiments involved direct absorption and spraying. The aim of this study was to evaluate the potential for tolerance and reaction to high levels of benzene. Three plant species were used...

Human risk assessment of benzene after a gasoline station fuel leak

Santos,Miriam dos Anjos; Tavora,Bruno Esteves; Koide,Sergio; Caldas,Eloisa Dutra
Fonte: Faculdade de Saúde Pública da Universidade de São Paulo Publicador: Faculdade de Saúde Pública da Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 EN
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OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L) since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals). The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk). Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.

Increased Mitochondrial DNA Copy Number in Occupations Associated with Low-Dose Benzene Exposure

Carugno, Michele; Pesatori, Angela Cecilia; Dioni, Laura; Hoxha, Mirjam; Bollati, Valentina; Albetti, Benedetta; Bonzini, Matteo; Fustinoni, Silvia; Cocco, Pierluigi; Satta, Giannina; Zucca, Mariagrazia; Merlo, Domenico Franco; Cipolla, Massimo; Bertazzi,
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
EN_US
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Background: Benzene is an established leukemogen at high exposure levels. Although low-level benzene exposure is widespread and may induce oxidative damage, no mechanistic biomarkers are available to detect biological dysfunction at low doses. Objectives: Our goals were to determine in a large multicenter cross-sectional study whether low-level benzene is associated with increased blood mitochondrial DNA copy number (mtDNAcn, a biological oxidative response to mitochondrial DNA damage and dysfunction) and to explore potential links between mtDNAcn and leukemia-related epigenetic markers. Methods: We measured blood relative mtDNAcn by real-time polymerase chain reaction in 341 individuals selected from various occupational groups with low-level benzene exposures (> 100 times lower than the Occupational Safety and Health Administration/European Union standards) and 178 referents from three Italian cities (Genoa, Milan, Cagliari). Results: In each city, benzene-exposed participants showed higher mtDNAcn than referents: mtDNAcn was 0.90 relative units in Genoa bus drivers and 0.75 in referents (p = 0.019); 0.90 in Milan gas station attendants, 1.10 in police officers, and 0.75 in referents (p-trend = 0.008); 1.63 in Cagliari petrochemical plant workers...

NMR characterization of 13C-Benzene sorbed to natural and prepared charcoals

Smernik, R.; Kookana, R.; Skjemstad, J.
Fonte: Amer Chemical Soc Publicador: Amer Chemical Soc
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
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We investigated how the NMR properties of uniformly 13C-labeled benzene molecules are influenced by sorption to charcoals produced in the laboratory and collected from the field following wildfires. Uniformly 13C-labeled benzene was sorbed to two charcoals produced in the laboratory at 450 and 850 degrees C. The chemical shift of benzene sorbed to the higher-temperature charcoal was 5-6 ppm lower than that of benzene sorbed to the lower-temperature charcoal. This difference was attributed to stronger diamagnetic ring currents (which cause a shift to lower ppm values) in the more condensed or "graphitic" high-temperature charcoal. The chemical shift of benzene sorbed to two charcoals collected from the field following wildfires indicated a degree of charcoal graphitization intermediate between that of the two laboratory-prepared charcoals. Variable contact time and dipolar dephasing experiments showed that the molecular mobility of sorbed benzene molecules increased with increasing charcoal graphitization, and also increased with increasing benzene concentration. We propose that the chemical shift displacement of molecules sorbed to charcoal could be used to identify molecules sorbed to black carbon in heterogeneous matrixes such as soils and sediments...

General model for molecular interactions in a benzene dimer

Tran-Duc, T.; Thamwattana, N.; Cox, B.; Hill, J.
Fonte: Sage Publications Inc Publicador: Sage Publications Inc
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
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Modelling molecular interactions in a benzene dimer is a typical example of a class of problems involving aromatic molecules. Although many studies on the benzene dimer have been carried out both theoretically and experimentally and energetically favorable structures of a benzene dimer have been found, an investigation of all equilibrium structures of a benzene dimer has not so far been done. Previously, the present authors investigated the interaction energy and geometries of a benzene dimer for the special case in which only one rotational angle is used to describe the relative position between two benzene molecules. In general, two rotational angles are necessary to describe the most general relative orientation. Here, we apply the same approach in which the discrete atomic structure of a benzene molecule is replaced by two continuous rings of atoms, namely an inner carbon ring and an outer hydrogen ring with average constant atomic densities and the molecular interaction forces are calculated from the Lennard-Jones potential function. An analytical expression for the interaction energy is obtained which we use to determine all equilibrium structures of a benzene dimer as well as to determine those domains in which certain configurations are more favorable than others. Our results show that parallel...

Dynamics of benzene molecules situated in metal-organic frameworks

Chan, Y.; Hill, J.
Fonte: Baltzer Sci Publ BV Publicador: Baltzer Sci Publ BV
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
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In this paper, we investigate the gyroscopic motion of a benzene molecule C6H6, which comprises an inner carbon ring and an outer hydrogen ring, and is suspended rigidly inside a metal-organic framework. The metal-organic framework provides a sterically unhindered environment and an electronic barrier for the benzene molecule. We model such gyroscopic motion from the inter-molecular interactions between the benzene ring and the metal-organic framework by both the Columbic force and the van der Waals force. We also capture additional molecular interactions, for example due to sterical compensations arising from the carboxylate ligands between the benzene molecule and the framework, by incorporating an extra empirical energy into the total molecular energy. To obtain a continuous approximation to the total energy of such a complicated atomic system, we assume that the atoms of the metal-organic framework can be smeared over the surface of a cylinder, while those for the benzene molecule are smeared over the contour line of the molecule. We then approximate the pairwise molecular energy between the molecules by performing line and surface integrals. We firstly investigate the freely suspended benzene molecule inside the framework and find that our theoretical results admit a two-fold flipping...

Investigating benzene-initiated DNA double-strand breaks and recombination after acute and in utero exposure in mice

Lau, Annette Anling
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 1470412 bytes; application/pdf
EN; EN
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Benzene is an ubiquitous pollutant and industrial solvent that has been identified as a human leukemogen. Early exposure to environmental carcinogens such as benzene has been postulated to play a role in the etiology of childhood leukemia, however the association remains controversial. Genotoxic agents such as benzene can cause an increase in the frequency of DNA double-strand breaks, which may remain unrepaired or result in the initiation of DNA recombinational repair mechanisms. The first objective was to investigate the induction of DNA double-strand breaks following in utero treatment to 200 mg/kg and 400 mg/kg benzene i.p. using the phosphorylated histone γ-H2A.X as a marker. Using immunoblotting, treatment with benzene did not increase the formation of γ-H2A.X in bone marrow cells of adult C57Bl/6N male mice and in maternal bone marrow, fetal liver, and post-natal bone marrow cells following in utero exposure to 200 mg/kg or 400 mg/kg benzene throughout gestational days 7 to 15. Secondly, the study investigated the induction of micronuclei following in utero exposure to benzene. Acute exposure to 400 mg/kg benzene resulted in a statistically significant increase in the percentage of micronucleated cells in adult male bone marrow cells. In utero exposure to 400 mg/kg benzene throughout gestational days 7 to 15 also caused a statistically significant increase in the percentage of micronucleated cells in maternal bone marrow and post-natal bone marrow cells. Fetal liver cells also demonstrated a statistically significant increase in the percentage of micronucleated cells following 200 mg/kg and 400 mg/kg benzene. The third objective was to investigate the initiation of DNA recombination following in utero exposure to benzene using the pKZ1 mutagenesis mouse model as a surrogate marker for non-homologous end joining activity. Adult pKZ1 mouse tissue yielded no recombination events; however...

Investigating the Mechanisms of Toxicity of Benzene and its Metabolite Benzoquinone and the Role of Sulforaphane as a Potential Protective Agent in CD-1 Mouse Development

Philbrook, Nicola
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
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Benzene is an environmental pollutant and a known human leukemogen. It is also suspected to be associated with in utero-initiated leukemia. However, the mechanisms of benzene-mediated toxicity and carcinogenicity in both adults and fetuses are not well understood. Two main research hypotheses were tested in this thesis work. The first was that exposure to the benzene metabolite, benzoquinone, leads to increased levels of reactive oxygen species (ROS) and DNA damage in cultured mouse fetal liver cells, and that epigenetic changes in CD-1 mouse fetal livers would result from in vivo exposure to benzene. The second was that exposure to the phytochemical, sulforaphane (SFN), would induce detoxification enzymes in CD-1 mouse fetal livers in vitro and in vivo, and that this would confer protection against benzene-induced cellular damage. Our data demonstrated that exposure to benzoquinone increased ROS levels, increased DNA damage, and altered DNA repair gene expression in cultured CD-1 mouse fetal liver cells. Additionally, although we found that SFN induced various metabolizing enzymes involved in the detoxification of benzene metabolites, SFN did not protect against the deleterious effects of benzene found in this study. In a separate study...

Investigating the role of reactive oxygen species in transplacental benzene carcinogenesis

Badham, Helen J
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 13312436 bytes; application/pdf
EN; EN
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The incidence of childhood leukemia is increasing, especially in urbanized areas. It is hypothesised that transplacental exposure to environmental carcinogens, such as benzene, plays a role in the etiology of childhood cancers. The studies in this thesis investigated mechanisms of transplacental benzene tumourigenesis focusing on the role of reactive oxygen species (ROS). Initially, we investigated the effect of maternal benzene exposure on fetal erythroid progenitor cell number and the role of ROS in benzene metabolite-induced dysregulation of erythropoiesis. In the CD-1 mouse, in utero benzene exposure caused significant alterations in female fetal liver erythroid progenitor cell numbers at gestational day 16 and postnatal day 2. Using an in vitro chicken erythroblast cell line capable of erythropoiesis, we found that hydroquinone significantly inhibited erythropoiesis and this effect was prevented by pretreatment with PEG-superoxide dismutase. The second objective investigated the role of ROS in dysregulated fetal hematopoietic progenitor cell growth after maternal benzene exposure in C57Bl/6N mice. In utero exposure to benzene caused changes in fetal hematopoietic progenitor cell numbers, an increase in levels of fetal liver intracellular ROS...

Outdoor and indoor benzene evaluation by GC-FID and GC-MS/MS

Sousa, José A.; Domingues, Valentina F.; Rosas, Mónica S.; Ribeiro, Susana; Alvim-Ferraz, Maria da Conceição M.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2011 ENG
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The evaluation of benzene in different environments such as indoor (with and without tobacco smoke), a city area, countryside, gas stations and near exhaust pipes from cars running on different types of fuels was performed. The samples were analyzed using gas chromatography (GC) with flame ionization detection (FID) and tandem mass spectrometric detection (MS/MS) (to confirm the identification of benzene in the air samples). Operating conditions for the GC-MS analysis were optimized as well as the sampling and sample preparation. The results obtained in this work indicate that i) the type of fuel directly influences the benzene concentration in the air. Gasoline with additives provided the highest amount of benzene followed by unleaded gasoline and diesel; ii) the benzene concentration in the gas station was always higher than the advisable limit established by law (5 μg m−3) and during the unloading of gasoline the achieved concentration was 8371 μg m−3; iii) the data from the countryside (Taliscas) and the urban city (Matosinhos) were below 5 μg m−3 except 5 days after a fire on a petroleum refinery plant located near the city; iv) it was proven that in coffee shops where smoking is allowed the benzene concentration is higher (6 μg m−3) than in coffee shops where this is forbidden (4 μg m−3). This method may also be helpful for environmental analytical chemists who use GC-MS/MS for the confirmation or/and quantification of benzene.

Prevenção da exposição ao benzeno no Brasil; Prevention against exposure to benzene in Brazil

Costa, Danilo Fernandes
Fonte: Universidade de São Paulo. Faculdade de Medicina Publicador: Universidade de São Paulo. Faculdade de Medicina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; DTR2; Formato: application/pdf
Publicado em 07/12/2009 POR
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A prevenção da exposição ao benzenotêm sido uma preocupação em diversos países desde o final do século XIX. Neste estudo foi feita uma recuperação do percurso histórico da utilização industrial do benzeno no Brasil, da produção técnico-científica sobre a saúde dos trabalhadores a ele expostos e dos conflitos sociais que tiveram maior repercussão, identificando com isto os elementos presentes nestes processos capazes de dar resposta à indagação central da investigação: se as restrições legais à exposição ao benzeno influenciaram positivamente na prevenção da exposição a esta substância no país. A experiência internacional serviu como contraponto, pois muitas situações que ocorreram nos países centrais se repetiram posteriormente nos países de industrialização tardia. Os resultados mostraram que, no Brasil e no mundo, pode-se dividir em quatro períodos a exposição a benzeno. Um período inicial, com pouco uso e quase sem notícias de casos. Um segundo momento em que a utilização aumenta de forma significativa e as exposições se tornam importantes: na experiência internacional este é um momento de ocorrência de muitos casos de Aplasia de Medula; no Brasil, apesar das exposições também altas...

Bacterial population dynamics and separation of active degraders by stable isotope probing during benzene degradation in a BTEX-impacted aquifer

ABURTO,Arturo; BALL,Andrew S.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2009 EN
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The activity and diversity of a groundwater bacterial community was studied during the degradation of benzene in samples from a BTEX-contaminated aquifer (SIReN, UK) through the use of denaturing gradient gel electrophoresis (DGGE), followed by excision and sequencing of dominant bands. Rapid aerobic benzene degradation occurred in all samples, with 60-70 % degradation of benzene. DGGE analysis revealed that unique, stable bacterial communities were formed in each sample. Pseudomonas putida and Acidovorax delafieldii were identified in groundwater samples 308s and W6s respectively, suggesting they are the important taxa involved in the degradation of benzene. Further work based on stable isotope probing (SIP) of RNA using 13C benzene was carried out. Prominent bands were identified as Acidovorax and Malikia genera; the latter is very similar to the benzene-degrader Hydrogenophaga, which confirms the presence of active benzene degraders in the groundwater samples. The identification of the prominent communities provides knowledge of the bioremediation processes occurring in situ and the potential to enhance degradation. This study highlights the potential of combining community fingerprinting techniques, such as DGGE, together with SIP.

Human risk assessment of benzene after a gasoline station fuel leak

Santos,Miriam dos Anjos; Tavora,Bruno Esteves; Koide,Sergio; Caldas,Eloisa Dutra
Fonte: Faculdade de Saúde Pública da Universidade de São Paulo Publicador: Faculdade de Saúde Pública da Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 EN
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OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L) since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals). The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk). Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.