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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Etude du lien entre l’exposition aux polluants organiques persistants et l’endométriose / Relationship between exposure to persistent organic pollutants and endometriosis

Ploteau, Stéphane 07 October 2016 (has links)
L’endométriose est une maladie gynécologique pour laquelle l’exposition à certains contaminants chimiques environnementaux est évoquée parmi les facteurs de risque associés. Les conclusions des études épidémiologiques existantes restent toutefois non convergentes. Leur hétérogénéité en termes de lésions décrites, de méthodologie et d’effectifs contribuent à ce constat, de même que l’étendue limitée des marqueurs d’exposition considérés dans ces études. Nous avons réalisé une étude cas-témoins appariés à partir d’une bio-collection de 113 patientes réunissant68 cas de patientes opérées d’endométriose profonde et 45 patientes témoins. Un ensemble unique de 78 polluants organiques persistants a été recherché, incluant dioxines, polychlorobiphényles, retardateurs de flamme polybromés, et pesticides organochlorés. Les niveaux d’exposition interne des sujets ont été mesurés à la fois dans les tissus adipeux pariétal et épiploïque ainsi que dans le sérum. La distribution de ces différents polluants au sein de ces trois compartiments a tout d’abord été caractérisée. Celle-ci a permis la prise en compte encore très rare de l’équilibre entre compartiments de stockage et compartiment circulant, ce rapport de concentration apparaissant comme un potentiel indicateur additionnel permettant d’affiner d’éventuels liens de causalité entre exposition chronique à des dangers chimiques et pathologie chez l’homme. Certains des contaminants ciblés sont ensuite apparus significativement associés à l’endométriose profonde, la stratification plus fine de notre population de cas indiquant un lien d’autant plus significatif en présence d’endométriome. Les mécanismes sous-jacents de cette association restent toutefois à élucider. / Endometriosis is a gynecological disease for whichexposure to some environmental chemicals is evocatedamong the associated risk factors. Epidemiological studies are however globally non convergent and finally fairly conclusive. Their heterogeneity in terms of lesion localization and sub-phenotype, methodology, size and nature of the populations studied, as well as the limited number of monitored markers of exposure contribute to this situation. We realized a matched case-control study based on a biocollection of 113 patients including 68 patients suffering of deep endometriosis and 45 controls. We characterized the internal exposure levels of an extended range of around 78 persistent organic pollutants (including dioxins, polychlorobiphenyls, brominated flame retardants and organochlorine pesticides). Internal level exposures were measured in three biological compartments (omental fat, subcutaneous fat and serum). First, the distribution of these chemicals was characterized within these compartments. These extended exposure data from deep infiltrating endometriosis patients are the first ones available for France and give a new insight about the equilibrium of chemicals between storage and circulating compartments that should be further considered as a potential indicator permitting to establish a possible association between a chronic exposure to chemical hazards and human pathology. Afterwards, some of the targeted chemicals appeared significantly associated with deep endometriosis. A sub-stratification of our case population indicated a more significant relationship with the presence of endometrioma. Underlying mechanisms remain to be determined.
32

Origin of Dioxins in Queensland: Investigations into the Distribution and Sources of Polychlorinated Dibenzo-P-Dioxins in the Queensland Terrestrial Environment

Prange, Joelle, n/a January 2004 (has links)
Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are persistent organic pollutants of global concern as they are persistent, toxic and can biomagnify through the food chain. PCDD/Fs are generally regarded as trace contaminants in a number of chemical products and they are formed as by-products from various industrial, chemical and combustion processes. The pollution with PCDD/Fs occurs with the release of these chemicals into the environment, resulting in the contamination of various compartments including; air, soil, sediment and biota. Studies that have investigated the distribution of PCDD/Fs in the environment suggest that the highest concentrations of these pollutants are found in locations with a history of industrial or chemical PCDD/F sources. Queensland is the north-eastern state of Australia. Queensland has a low population density, few industrial activities and is considered predominantly rural. Therefore it was somewhat surprising that elevated concentrations of PCDD/Fs (in particular the higher chlorinated PCDDs) have been observed in soil and sediments samples collected from various locations along the Queensland coast. The concentrations of PCDDs in Queensland samples were comparable to or higher than concentrations in similar matrices from highly polluted regions elsewhere. To investigate the origin of PCDDs in Queensland, the geographical distribution of PCDD/Fs in topsoil was investigated in the coastal and inland environments to provide information on the potential sources and to estimate the extent of the PCDD contamination. Distinct east-west gradients were detected in topsoil collected from bushland areas across the state with elevated PCDD concentrations confined to the coastal region. Within the coastal region, the contamination could not be associated with specific land uses. In fact, the PCDD/F congener profile was similar in the majority of samples from the coastal region, with a dominance of the higher chlorinated PCDDs (in particular OCDD), whereas PCDFs were low or below the limit of detection. The similarity in the PCDD/F congener profiles in the soils along the coastal region indicated that a source of PCDDs of similar origin has resulted in the contamination of soil extending more than 3000 km and estimations suggest that more than 50 tonnes of OCDD is stored in the topsoil of Queensland.s coastal region. Investigation into the vertical distribution of PCDDs in Queensland coastal soils revealed elevated concentrations of PCDDs, (in particular OCDD) in soils to at least 3.5 m. These results indicated that the extent of the PCDD contamination is significantly greater than anticipated and it was estimated that there is in the order of 3 000 tonnes of OCDD stored in Queensland's coastal soils. The specific PCDD/F congener profile in Queensland coastal soils is unlike known PCDD/F source profiles which led to the suggestion that some yet unidentified formation mechanism may have resulted in the contamination. Potential natural sources of PCDD/Fs, including forest fires, geogenic and biogenic processes were assessed as possible origins for the PCDD contamination in Queensland. Elevated concentrations of PCDDs were detected in the atmosphere during a 'prescribed burn'. This study demonstrated that although forest fires influence atmospheric PCDD/F concentrations substantially, forest fires are not the source of PCDDs in Queensland; rather they are an important mechanism for the redistribution of PCDDs and may have attributed to the widespread PCDD contamination. In this study geological materials (oil shale and kaolin) were analysed as a proxy to assess a geogenic origin of PCDDs. Elevated concentrations of PCDDs were observed in the kaolin samples, however similar and higher concentrations were detected in surface and sub-surface soils, suggesting that specific geogenic formation processes investigated are not the source of PCDDs in Queensland. A preliminary indication for a biogenic origin of PCDDs was identified during the anaerobic incubation of sugarcane irrigation sediments. An increase in the concentration of OCDD in the anaerobic treatment, compared to the control was observed after incubation for 90 days. In these same experiments, a dechlorination of OCDD to lower chlorinated (1,4,6,9-substituted) PCDDs was also observed. Similar transformation processes were observed in other anaerobic environments in Queensland, which led to the suggestion that a biogenic formation of PCDDs (possibly from a precursor) may be responsible for the origin of PCDDs in Queensland.
33

Dioxins in the Marine Environment: Sources, Pathways and Fate of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Queensland, Australia

Gaus, Caroline, n/a January 2003 (has links)
Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans(PCDFs) are two groups of lipophilic, persistent organic pollutants that are produced as by-products of various anthropogenic and industrial processes. Due to their relatively high toxic potencies and potential to bioaccumulate and biomagnify in organisms and through the food chain, the contemporary widespread distribution of these compounds is a concern to the health of the environment, wildlife and humans. This study determined the distribution, pathways and fate of PCDD/Fs in the coastal zone of Queensland, Australia, including the inshore marine environment of the World Heritage Great Barrier Reef Marine Park. This ecosystem supports unique fauna and flora such as the marine herbivorous mammal dugong (Dugong dugon) and its food source, seagrass. Elevated PCDD/Fs were present in soils and sediments along the entire Queensland coastline. Highest concentrations were found in soil from agricultural irrigation drains and in sediments near the mouths of major rivers. Elevated concentrations were associated with rural and urban types of land-use, and PCDD/Fs were present even in locations remote from anthropogenic activities. PCDD/F congener-specific analysis revealed an unusual profile in all samples, dominated by OCDD, with PCDFs present in low concentrations or below the limit of detection. Distinct HxCDD isomer patterns were observed, with the 1,2,3,7,8,9-HxCDD/1,2,3,4,6,7-HxCDD isomer pair dominating the 2,3,7,8-substituted HxCDDs. Similar congener and isomer characteristics were reported in sediments, soil and clay samples from other continents, but could not be attributed to any known source. Possible PCDD/F sources in Queensland were assessed using segmented estuarine sediment cores, for which radiochemical chronologies were established for each depth. Variations of PCDD/F concentrations in the sediment cores over several centuries of depositional history were relatively small. Elevated PCDD levels were still present in sediment slices from the early 17th century. PCDD/F homologue profiles in sediments deposited during the last 350 years were almost identical and correlated well to the characteristic profiles observed in surface sediments and soils from the entire Queensland coastline. These results suggested the presence of an unidentified PCDD source prior to the production of commercial organochlorine products. To investigate the formation of the unusual PCDD/F profiles, congener and isomer specific analyses were undertaken in soils, sediments and dated sediment cores. The results demonstrated that specific transformation processes in the environment have resulted in the observed PCDD profile characteristics. Dechlorination of OCDD was proposed to result in distinct 1,4-pattern characteristics (i.e. formation of isomers chlorinated in the 1,4,6,9-positions). Consequently, the environmental samples do not reflect the signatures of the original source. An alternative hypothesis to natural formation is discussed evaluating these processes and their implications for possible source contributions. This hypothesis explores the potential for the influence of anthropogenic PCDD precursors (e.g. pentachlorophenol) during the 1940s to 1990s. Transport of PCDD/Fs from the land-based source via impacted tributary river systems, and subsequent deposition processes are proposed to result in PCDD/F accumulation in the inshore marine ecosystem. The extent of the sediment PCDD/F contamination governs the concentrations in the extensive inshore marine seagrass meadows of Queensland. Partitioning processes in the sediment-seagrass system lead to increased toxic equivalency (TEQ) in the seagrass, compared to sediment.The relationship between contaminated inshore sediments, seagrass and dugongs were evaluated using six dugong habitat regions along the coastline. PCDD/F body burdens in dugongs are governed by sediment (and seagrass) PCDD/F concentrations in their habitat. High seagrass (and incidental sediment) ingestion rates, selective retention of toxicologically potent congeners and relatively low PCDD/F elimination capacities in dugongs are proposed to result in elevated PCDD/F concentrations and TEQ levels in adult animals. Transfer efficiencies of 4 and 27% of maternal TEQ levels to foetuses and calves (respectively) during gestation and lactation result in relatively high exposure potentials to offspring. Compared to no-observed-adverse-effect-levels in other mammals, and based on the results of this study, a tolerable daily intake (TDI) of 10-24 pg TEQ kg-1 day-1 was estimated for dugongs. The results of the present study found that dugongs from some regions along the coastline of Queensland exceed this TDI by up to 20 fold, suggesting that these populations may be at risk from PCDD/F contamination in their habitat. These results have important implications for the health of the environment, wildlife and humans and were used to develop a conceptual understanding of the sources, pathways and fate of dioxins in Queensland, Australia.
34

Dioxins and dioxin-like compounds in thermochemical conversion of biomass : formation, distribution and fingerprints

Gao, Qiuju January 2016 (has links)
In the transition to a sustainable energy supply there is an increasing need to use biomass for replacement of fossil fuel. A key challenge is to utilize biomass conversion technologies in an environmentally sound manner. Important aspects are to minimize potential formation of persistent organic pollutants (POPs) such as dioxins and dioxin-like compounds. This thesis involves studies of formation characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) in microwave-assisted pyrolysis (MAP) and torrefaction using biomass as feedstock. The research focuses are on their levels, distributions, fingerprints (homologue profiles and isomer patterns) and the underlying formation pathways. The study also included efforts to optimize methods for extracting chlorinated aromatic compounds from thermally treated biomass. The overall objective was to contribute better understanding on the formation of dioxins and dioxin-like compounds in low temperature thermal processes. The main findings include the following: Pressurized liquid extraction (PLE) is applicable for simultaneous extraction of PCDDs, PCDFs, PCNs, polychlorinated phenols and benzenes from thermally treated wood. The choice of solvent for PLE is critical, and the extraction efficiency depends on the degrees of biomass carbonization. In MAP experiments PCDDs, PCDFs and PCNs were predominantly found in pyrolysis oils, while in torrefaction experiments they were mainly retained in solid chars with minor fractions in volatiles. In both cases, highly chlorinated congeners with low volatility tended to retain on particles whereas the less chlorinated congeners tended to volatize into the gas phase. Isomer patterns of PCDDs, PCDFs and PCNs generated in MAP were more selective than those reported in combustion processes. The presence of isomers with low thermodynamic stability suggests that the pathway of POPs formation in MAP may be governed not only by thermodynamic stabilities but also by kinetic factors. Formation of PCDDs, PCDFs and PCNs depends not only on the chlorine contents in biomass but also the presence of metal catalysts and organic/metal-based preservatives. Overall, the results provide information on the formation characteristics of PCDDs, PCDFs and PCNs in MAP and torrefaction. The obtained knowledge is useful regarding management and utilization of thermally treated biomass with minimum environmental impact.
35

Toxicidade equivalente da atmosfera por dioxinas, furanos e bifenilas policloradas,com uso de duas técnicas de coleta, passiva e ativa / Equivalent toxicity of the atmosphere for dioxins, furans and polychlorinated biphenyls, using two air sampling techniques, passive and active

Francisco, Ana Paula 13 June 2017 (has links)
Introdução: Dioxinas, furanos e bifenilas policloradas são poluentes tóxicos para a saúde humana incluindo riscos de incidência de cânceres, efeitos de neurodesenvolvimento, lesões dérmicas, cloroacne. Estes compostos são poluentes orgânicos persistentes (POPs) que podem ser transportados de longas distâncias da fonte de emissão e se bioacumular em ecossistemas. A atmosfera poluída foi recentemente classificada como carcinogênica para os seres humanos pela Organização Mundial da Saúde, mostrando a importância de sua caracterização, principalmente para compostos tóxicos. Entretanto, técnica de coleta ativa tem custo elevado para POPs, e existem poucos estudos de calibração que validem a substituição. Objetivos: Avaliar a toxicidade equivalente da atmosfera por dioxinas, furanos e bifenilas cloradas, utilizando técnicas de coleta ativa e passiva, e verificar gradiente de concentração nos ambientes urbano, urbano/industrial e de background. Método: Amostras de ar foram coletadas, utilizando coletores ativos e passivos, durante dois períodos consecutivos de quatro meses: de setembro a dezembro de 2014 (período 1) e de maio a agosto de 2015 (período 2) em três cidades de São Paulo, SP, em ambientes urbano, urbano/industrial e de background. Todas as amostras foram extraídas com solução de tolueno:acetona (9:1) em Soxhlet por 24 h e padrões marcados (13C12-PCDD/Fs e 13C12-PCBs) foram adicionados em cada amostra antes do processo de extração. Os extratos foram purificados em coluna de sílica mista (40 por cento H2SO4 e 10 por cento AgNO3) seguida por coluna de alumina. O procedimento analítico foi realizado utilizando HRGC/HRMS (High Resolution Gas Chromatograph/High Resolution Mass Spectrometer) operando em ionização de impacto de elétrons com energia de 35 eV no modo SIM (Select Ion Monitoring) e resolução de 10.000. Resultados mostraram que: (1) existe variação sazonal para concentrações de PCDD/Fs no ar entre os períodos 1 e 2 (p=0,03), enquanto as concentrações de dl-PCBs não foram estatisticamente diferentes nestes períodos (p=0,52); (2) existe gradiente de concentração de PCDD/Fs e dl- PCBs que aumenta na seguinte ordem: background<urbano<urbano/industrial, porém não foi encontrada diferença significante entre as concentrações dos locais urbano e urbano/industrial para as amostras da coleta ativa; (3) as concentrações de PCDD/Fs e dl-PCBs das amostras do coletor ativo variaram de 9,34 a 221 fg TEQ/m³ no período 1, e entre 7,76 a 453 fg TEQ/m³ no período 2; nas amostras dos coletores passivos estas concentrações variaram de 6,11 a 32,2 fg TEQ/m³ no período 1, e entre 48,6 e 298 fg TEQ/m³ no período 2; (4) a estimativa da taxa de coleta utilizando duas abordagens diferentes mostrou discrepâncias. Conclusões: Os resultados dos coletores ativos e passivos estão em boa concordância em termos de tendências espacial e temporal, assim como os perfis de congêneres e grupos homólogos, a coleta passiva com disco de PUF mostrou-se como uma técnica adequada para determinação de PCDD/Fs e dl-PCBs / Introduction: Dioxins, furans and polychlorinated biphenyls are toxic pollutants for human health including risks of cancer incidence, neurodevelopmental effects, dermal lesions, chloracne. These compounds are persistent organic pollutants (POPs) that can be transported to long distances from the emission source and they are bioaccumulated in ecosystems. Recently, the outdoor air pollution were classified as carcinogenic to humans by the World Health Organization, showing the importance of its characterization for toxic compounds. However, active air monitoring has a high cost for POPs, and there is a few calibration studies which support that substitution. Objective: To assess the equivalent toxicity of the atmosphere regarding the measurement of dioxins, furans and polychlorinated biphenyls, using active and passive air samplers, and to evatuate the contrasting concentrations at urban, urban/industrial and background sites. Method: Air samples were collected, using active and passive samplers, over two consecutive periods of four months: from September to December 2014 (period 1) and from May to August 2015 (period 2) at three cities in São Paulo, SP, covering urban, urban/industrial and background sites. All samples were extracted with toluene:acetone (9:1) in a Soxhlet apparatus for 24 hours and surrogate standards (13C12-PCDD/F and 13C12-PCBs) were spiked on each sample media prior to extraction procedure. The extracts were purified on an silica column (40 per cent H2SO4 and 10 per cent AgNO3) followed by an alumina column. The analytical procedure was carried out using HRGC/HRMS (High Resolution Gas Chromatograph/High Resolution Mass Spectrometer) operating in electron impact ionization with an energy of 35 eV in SIM (selected ion monitoring) mode and 10.000 resolution power. Results show that (1) there are seasonal variations for PCDD/F concentrations in air between period 1 and 2 (p=0.03), whereas dl-PCB levels were not statistically different (p=0.52) in those periods. (2) PCDD/F and dl-PCB air levels are in the following order: background <urban <urban/industrial for both active and passive samplers; (3) PCDD/F and dl-PCB concentrations in active air samples ranged from 9.34 to 221 fg TEQ/m³ in period 1, and between 7.76 and 453 fg TEQ/m³ in period 2; in the passive air samples, these concentrations ranged from 6.11 to 32.2 fg TEQ/m³ in period 1, and between 48.6 and 298 fg TEQ/m³ in period 2; (4) the estimation of sampling rate using two approachs for PCDD/Fs showed differences. Conclusions: Passive and active air sampling results are in good agreement in spatial terms and temporal trends, as are the congener and homologue profiles, showing that passive air sampling of PUF disk is a powerful sampler for PCDD/F and dl-PCB measurements
36

Aspectos técnicos e ambientais da incineração de resíduos sólidos urbanos: considerações sobre a proposta para São Paulo / Technical and environmental aspects on the incineration of urban solid waste: considerations on the proposal for São Paulo city

Gripp, William Gomes 22 June 1998 (has links)
A tecnologia de incineração no gerenciamento de resíduos sólidos urbanos é empregada de maneira intensa em diversos países do mundo. No Brasil, além da sua utilização eventual em resíduos de serviços de saúde, há uma proposta para implantação de duas usinas de grande porte visando ao tratamento térmico de resíduos sólidos domiciliares na cidade de São Paulo. Através de uma revisão bibliográfica sobre o tema, são apresentados os principais parâmetros técnicos e ambientais desta tecnologia, entre eles os mecanismos de combustão e de formação de poluentes, os tipos de equipamentos empregados, as formas de manejo e disposição de cinzas e escórias e os métodos de controle e redução de emissões atmosféricas como gases ácidos, material particulado e metais pesados. Também é feita uma revisão do atual conhecimento técnico-científico sobre dioxinas e furanos relativamente à incineração de resíduos sólidos urbanos. A partir desta base teórica pesquisada e da análise dos Estudos de Impacto Ambiental e dos Relatórios de Impacto Ambiental das usinas de incineração de Santo Amaro e Sapopemba, conclui-se que tais incineradores, na forma como são propostos, não apresentam o nível tecnológico necessário para atender às normas de operação e emissão de poluentes vigentes em países onde há legislação regulando esta atividade. / The incineration technique on the management of municipal solid waste is intensely used in several countries. In Brazil, besides an occasional utilization on medical services waste, there is a proposal for the implantation of two large facilities for the thermal treatment of domestic solid waste in São Paulo city. Through a review on this theme, we present here the main technical and environmental parameters on this technology, including the combustion and the pollutant generation mechanisms, types of equipment, management and disposition of fly and bottom ashes and the main control and reduction methods of atmospheric pollution like acid gases, particulates and heavy metals. The state of the art on the present technical-scientific knowledge on dioxins and furans connected to the incineration of urban solid waste is presented. On this theoretical basis and on the analysis of the environmental impact assessment and environmental impact report on the Santo Amaro and Sapopemba facilities, we conclude that the incineration systems, as in the proposal, do not present the technologic level necessary to obey the operation and pollutant emission rules on the countries where this activities are controlled.
37

Toxicidade equivalente da atmosfera por dioxinas, furanos e bifenilas policloradas,com uso de duas técnicas de coleta, passiva e ativa / Equivalent toxicity of the atmosphere for dioxins, furans and polychlorinated biphenyls, using two air sampling techniques, passive and active

Ana Paula Francisco 13 June 2017 (has links)
Introdução: Dioxinas, furanos e bifenilas policloradas são poluentes tóxicos para a saúde humana incluindo riscos de incidência de cânceres, efeitos de neurodesenvolvimento, lesões dérmicas, cloroacne. Estes compostos são poluentes orgânicos persistentes (POPs) que podem ser transportados de longas distâncias da fonte de emissão e se bioacumular em ecossistemas. A atmosfera poluída foi recentemente classificada como carcinogênica para os seres humanos pela Organização Mundial da Saúde, mostrando a importância de sua caracterização, principalmente para compostos tóxicos. Entretanto, técnica de coleta ativa tem custo elevado para POPs, e existem poucos estudos de calibração que validem a substituição. Objetivos: Avaliar a toxicidade equivalente da atmosfera por dioxinas, furanos e bifenilas cloradas, utilizando técnicas de coleta ativa e passiva, e verificar gradiente de concentração nos ambientes urbano, urbano/industrial e de background. Método: Amostras de ar foram coletadas, utilizando coletores ativos e passivos, durante dois períodos consecutivos de quatro meses: de setembro a dezembro de 2014 (período 1) e de maio a agosto de 2015 (período 2) em três cidades de São Paulo, SP, em ambientes urbano, urbano/industrial e de background. Todas as amostras foram extraídas com solução de tolueno:acetona (9:1) em Soxhlet por 24 h e padrões marcados (13C12-PCDD/Fs e 13C12-PCBs) foram adicionados em cada amostra antes do processo de extração. Os extratos foram purificados em coluna de sílica mista (40 por cento H2SO4 e 10 por cento AgNO3) seguida por coluna de alumina. O procedimento analítico foi realizado utilizando HRGC/HRMS (High Resolution Gas Chromatograph/High Resolution Mass Spectrometer) operando em ionização de impacto de elétrons com energia de 35 eV no modo SIM (Select Ion Monitoring) e resolução de 10.000. Resultados mostraram que: (1) existe variação sazonal para concentrações de PCDD/Fs no ar entre os períodos 1 e 2 (p=0,03), enquanto as concentrações de dl-PCBs não foram estatisticamente diferentes nestes períodos (p=0,52); (2) existe gradiente de concentração de PCDD/Fs e dl- PCBs que aumenta na seguinte ordem: background<urbano<urbano/industrial, porém não foi encontrada diferença significante entre as concentrações dos locais urbano e urbano/industrial para as amostras da coleta ativa; (3) as concentrações de PCDD/Fs e dl-PCBs das amostras do coletor ativo variaram de 9,34 a 221 fg TEQ/m³ no período 1, e entre 7,76 a 453 fg TEQ/m³ no período 2; nas amostras dos coletores passivos estas concentrações variaram de 6,11 a 32,2 fg TEQ/m³ no período 1, e entre 48,6 e 298 fg TEQ/m³ no período 2; (4) a estimativa da taxa de coleta utilizando duas abordagens diferentes mostrou discrepâncias. Conclusões: Os resultados dos coletores ativos e passivos estão em boa concordância em termos de tendências espacial e temporal, assim como os perfis de congêneres e grupos homólogos, a coleta passiva com disco de PUF mostrou-se como uma técnica adequada para determinação de PCDD/Fs e dl-PCBs / Introduction: Dioxins, furans and polychlorinated biphenyls are toxic pollutants for human health including risks of cancer incidence, neurodevelopmental effects, dermal lesions, chloracne. These compounds are persistent organic pollutants (POPs) that can be transported to long distances from the emission source and they are bioaccumulated in ecosystems. Recently, the outdoor air pollution were classified as carcinogenic to humans by the World Health Organization, showing the importance of its characterization for toxic compounds. However, active air monitoring has a high cost for POPs, and there is a few calibration studies which support that substitution. Objective: To assess the equivalent toxicity of the atmosphere regarding the measurement of dioxins, furans and polychlorinated biphenyls, using active and passive air samplers, and to evatuate the contrasting concentrations at urban, urban/industrial and background sites. Method: Air samples were collected, using active and passive samplers, over two consecutive periods of four months: from September to December 2014 (period 1) and from May to August 2015 (period 2) at three cities in São Paulo, SP, covering urban, urban/industrial and background sites. All samples were extracted with toluene:acetone (9:1) in a Soxhlet apparatus for 24 hours and surrogate standards (13C12-PCDD/F and 13C12-PCBs) were spiked on each sample media prior to extraction procedure. The extracts were purified on an silica column (40 per cent H2SO4 and 10 per cent AgNO3) followed by an alumina column. The analytical procedure was carried out using HRGC/HRMS (High Resolution Gas Chromatograph/High Resolution Mass Spectrometer) operating in electron impact ionization with an energy of 35 eV in SIM (selected ion monitoring) mode and 10.000 resolution power. Results show that (1) there are seasonal variations for PCDD/F concentrations in air between period 1 and 2 (p=0.03), whereas dl-PCB levels were not statistically different (p=0.52) in those periods. (2) PCDD/F and dl-PCB air levels are in the following order: background <urban <urban/industrial for both active and passive samplers; (3) PCDD/F and dl-PCB concentrations in active air samples ranged from 9.34 to 221 fg TEQ/m³ in period 1, and between 7.76 and 453 fg TEQ/m³ in period 2; in the passive air samples, these concentrations ranged from 6.11 to 32.2 fg TEQ/m³ in period 1, and between 48.6 and 298 fg TEQ/m³ in period 2; (4) the estimation of sampling rate using two approachs for PCDD/Fs showed differences. Conclusions: Passive and active air sampling results are in good agreement in spatial terms and temporal trends, as are the congener and homologue profiles, showing that passive air sampling of PUF disk is a powerful sampler for PCDD/F and dl-PCB measurements
38

Exploring the role and the function of Aryl Hydrocarbon Receptor (AhR) and Aryl Hydrocarbon Nuclear Translocator (ARNT) in T cells

Rosenzweig, Ella January 2012 (has links)
The Aryl Hydrocarbon Receptor (AhR) and the Aryl Hydrocarbon Nuclear Translocator (ARNT) play a role in mediating transcriptional responses to environmental pollutants, including the highly toxic compound 2,3,7,8-tetrachlorodibenzo -p-dioxin (TCDD) but also endogenous physiological ligands. More recent studies have also indicated that the AhR plays a role in the immune system notably in effector Th17 cells where it seems to be critical for the production of the IL-22 cytokine. It is known that AhR ligands such as dioxins can suppress CD8 T cell mediated antiviral immune responses but it is not known whether this reflects a direct role of the AhR in CD8 T cells.Accordingly, one objective of the present study was to explore AhR and ARNT expression in CD8 T cells. The initial strategy was to probe AhR and ARNT expression by western blot analysis. A second approach was to develop a mouse model that would fate mark single lymphocytes that have activated AhR signaling pathways. A third strategy was to examine the impact of deletion of AhR and ARNT on CD8 T-cell function.The data show that AhR and ARNT expression in CD8 T cells is limited to immune activated effector cells and these transcription factors are not expressed in naïve CD8 T cells. There are only low levels of AhR complexes in conventional CD8 positive cytotoxic T cells. To investigate AhR function at the single cell level we developed a mouse model to fate mark cells that have activated AhR signaling. In this model a mouse expressing Cre recombinase ‘knocked in’ to the CYP1A locus (CYP1A1Cre+/-) was backcrossed to the R26REYFP reporter mouse. In R26REYFP mice, a gene encoding EYFP is knocked into the ubiquitously expressed Rosa26 locus preceded by a loxP flanked stop sequence. CYP1A1 expression is controlled by AhR/ARNT complexes and the concept of our model was that cells that express AhR and ARNT complexes and are triggered with AhR ligands will express Cre recombinase and delete the loxP flanked stop sequence in the R26REYFP reporter locus and hence begin to express YFP.In vitro experiments demonstrated the validity of this AhR reporter model. The in vitro data reveal that expression of functional AhR/ARNT complexes occurs during Th17 and Tc17 cell differentiation but only a very low frequency of cytotoxic T cells activates the AhR. In vivo data found no evidence for AhR activation during T cell development in the thymus but show strong evidence for activation of AhR/ARNT signaling in innate lymphocytes in the gut. The ARNT transcription factor is highly expressed in cytotoxic T cells. These cells do not express functional AhR complexes, yet we considered that ARNT might play a role in CD8 T cell biology because of its ability to dimerise with the transcription factor Hif-1a. Our studies of T cells lacking ARNT expression revealed that in CD4 T cells the ARNT transcription factor regulates IL-17 and IL-22 production. In CD8 T cells we discovered that Hif-1a/ARNT signaling controls glycolysis in immune activated cells by sustaining expression of glucose transporters and multiple rate limiting glycolytic enzymes. ARNT was not required for CD8 T cell proliferation but was required for immune activated CD8 T cells to normally differentiate to express perforin and granzymes and to acquire the migratory program of effector T cells. Importantly, we discovered that Hif-1a/ARNT signaling is regulated by mTOR (mammalian target of rapamycin) thus revealing a fundamental mechanism linking nutrient sensing and transcriptional control of CD8 T-cell differentiation.
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A Town Slowly Burned: Life and Death in a Small Louisiana Town

Bush, Victoria C. 18 May 2018 (has links)
When Tori Bush’s father died of chemical causes related to Agent Orange, she found herself obsessed with tracing dioxins, one of the main ingredient of Agent Orange in other American communities. She began to visit and interview residents of Mossville, Louisiana, a small town on the border of Texas, which has fourteen petrochemical facilities surrounding the town. The residents also had been exposed to dioxins. Grief and anger connected Tori to this story, but it is far larger—is the right to a healthy natural environment a part of our American citizenship?
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Estudio bibliométrico de la producción científica sobre dioxinas a través de las bases de datos Pubmed e I.M.E. (1997-2003)

Peña-Rey Lorenzo, Isabel 20 December 2004 (has links)
Introducción .Las dioxinas, son compuestos organoclorados que se acumulan en la cadena alimentaria, generando diversos problemas de salud. En el año 1997 fueron declarados carcinógenos humanos. Su principal fuente de producción son las incineradoras de residuos sólidos. Objetivos del estudio:Analizar la producción cientifica sobre dioxinas en los últimos 7 años; conocer la distribución de los articulos en las revistas, estudiar su distribución geográfica e idiomas, analizar la productividad de los autores, las pautas de firmas por autor y trabajo en equipo, la calidad de los articulos y el impacto de las revistas que publican sobre el tema, la existencia de los colegios invisibles y las enfermedades que más carga de enfermedad producen en los paises que publican sobre el tema. Material y método. Se utilizaron las bases de datos PubMed e Índice Médico Español (IME). Se crearon nuevas bases de datos en Reference Manager v.10 y se analizaron con SPSS v. 11.0 Se utilizó la base de datos Science Citation Index-Expanded para el estudio de las citas y Journal Citation Reports (JCR) para el estudio de la calidad de las revistas. Se aplicaron las leyes de Solla Price, la ley de Bradford y la ley de Lotka; se estudiaron el Índice de productividad y el de Transitoriedad de los autores, el Índice de Impacto y el Índice de Inmediatez de las revistas. Se hizo un control de la calidad de los articulos siguiendo los Requisitos de Uniformidad para Manuscritos enviados a Revistas Biomédicas del Comité Internacional de Directores de Revistas Médicas (CIDRM).Se analizaron y representaron los componentes de los colegios invisibles a través del estudio de las citas. Se estudió la morbi-mortalidad y la carga de enfermedad de las enfermedades que según la OMS existen en los paises más afectados por estos compuestos. Resultados Se encontraron 3.522 articulos. El número de articulos por año publicado se adecua a la Ley de Solla Price, con un coeficiente de correlación cercano a 1. De las 641 revistas que publican sobre el tema el núcleo de las zonas de Bradford lo compone la revista Chemosphere con 446 articulas, en el otro extremo hay 313 revistas que publican 1 solo articulo en los 7 años del estudio. El autor que más publica es Peterson con 42 artículos. La ecuación de Lotka se adapta a nuestro estudio. Las revistas que más publican tienen mayor factor de impacto. No hay diferencias en la calidad de los artículos publicados entre las que más y menos publican. Las tres enfermedades que producen mayor carga de enfermedad según la OMS en los paises productores de información sobre dioxinas son las enfermedades neuropsiquiátricas, cardiovasculares y neoplasias. Conclusiones: Se muestra la dispersión de la literatura cientifica en orden creciente. La mayoría de los artículos pertenecen a revistas publicadas en el pais de origen de la base de datos. Del análisis de los autores se reconocen grupos de investigación siendo los que más publican los que más se citan, y los que trabajan en conjunto. Los artículos con más de 7 autores son los que predominan al final del estudio. Las revistas que más artículos publican tienen con más frecuencia factor de impacto medido por JCR. La calidad de los artículos no difiere entre los autores más o menos prolíficos. No existe relación entre la publicación de artículos sobre dioxinas en los paises y una mayor prevalencia o incidencia de ciertos cánceres. Las enfermedades que más carga de enfermedad producen probablemente se deben a la presencia de otros factores más que a las dioxinas. / Introduction Dioxins were declared as human carcinogenic substances in 1997. They accumulate in food, and they can genera te health problems. The main dioxins producers are salid waste incinerators. Objectives: to analyse the scientific production about dioxins in the last 7 years, describing the distribution in journals, geographic distribution and the publication languages. To analyse the productivity of authors, the pattern of signatories / authors, the work teams and the relationship with burden of disease. Methods Sources of date: PubMed, I.M.E. (Spanish Medical Index) and Science Citation Index-Expanded databases. Data were analysed with SPSS 11.0 and Reference Manager 10.0 programs. Solla Price, Bradford and Lotka modeis were applied; the productivity index was computed; the Impact Factor and the Immediacy Index of journals were studied. A quality control of papers was done, taking into account the Uniform Requirements for Manuscript Submitted to Biomedical Journals of the International Commitee of Medical Journal Editors. Components of Invisible Colleges were assessed. Scientific production was linked to burden of disease produced by dioxins. Results 3522 articles were found. The number of articles published each year is fitted to Solla Price model, with a correlation coefficient clase to 1. The Bradford nucleus is the journal Chemosphere, with 446 articles. One author published 42 articles. The equation is fitted to Lotka's one, with an exponential change of -0.5. The most publisher journals have algo higher Impact Factor. No differences of quality of articles were founded among journals according to the number of published papers. Neuro-psychiatric and cardiovascular disorders and tumors were founded as the three groups that produce majar burden of disease in countries with higher information production on dioxins. Conclusions It has been shown the scientific literature dispersion. Majority of papers belong to journals edited in the origin country of database. Research groups of authors have be en found. Specialisation of some journals of Nucleus and 1st Bradford Zone has been shown. Burden of disease of some countries is not explained by contamination.

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