Dissertations / Theses: 'Dioxin'

1

Jansson, Stina. "Thermal formation and chlorination of dioxins and dioxin-like compounds." Doctoral thesis, Umeå universitet, Kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1881.

Full text

Abstract:

This thesis contributes to an increased understanding of the formation of dioxins and dioxin-like compounds in combustion processes. Although emissions to air from waste incineration facilities have been greatly reduced by the use of efficient air pollution control measures, the resulting residues (ashes and filters) are highly toxic and are classified as hazardous waste. The main objective of the work underlying this thesis was to elucidate the formation and chlorination pathways of dioxins and dioxin-like compounds in waste combustion flue gases in the temperature range 640-200°C in a representative, well-controlled laboratory-scale reactor using artificial municipal solid waste. This could contribute to the reduction of harmful emissions to air and also reduce the toxicity of waste incineration residues, thus reducing or even eliminating the need for costly and potentially hazardous after-treatment. A comparison of four different quenching profiles showed that the formation of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) was rapid and mainly occurred in the 640-400°C temperature region, with high dependency on sufficient residence time within a specific temperature region. Prolonged residence time at high temperatures (450/460°C) reduced the PCDD yields, even at lower temperatures along the post-combustion zone. PCDD, PCDF and PCN (polychlorinated naphthalene) isomer distribution patterns indicated contributions from chlorophenol condensation as well as chlorination reactions for all three classes of compounds. The formation of PCDDs was largely influenced by chlorophenol condensation and to some extent by chlorination reactions. For the PCDFs, chlorine substitution adjacent to the oxygen bridges was unfavoured, as demonstrated by the notably lower abundance of 1,9-substituted congeners. This was supported by bidirectional orthogonal partial least squares (O2PLS) modelling. The variable with the greatest influence on the distribution of PCDD congeners was the relative free energy (RΔGf). The O2PLS models displayed distinct clusters, dividing most of the homologues into two or three sub-groups of congeners which seemed to correspond to the probability of origination from chlorophenol condensation. The effects of injection of aromatic structures into the flue gas differed for each class of compounds. Injection of naphthalene increased the formation of monochlorinated naphthalene but the remaining homologues appeared to be unaffected. This was probably due to insufficient residence time at temperatures necessary for further chlorination. Injected dibenzo-p-dioxin was decomposed, chlorinated and re-condensated into PCDDs and PCDFs, whereas injection of dibenzofuran and fluorene reduced the PCDD levels in the flue gas.
Denna avhandling fokuserar på olika aspekter som kan bidra till en ökad förståelse av bildning av dioxiner och dioxin-lika föreningar i förbränningsprocesser. Även om utsläppen till luft från sopförbränningsanläggningar har minskat kraftigt tack vare effektiva rökgasreningsmetoder, så återstår problemet med mycket giftiga rökgasreningsprodukter (askor och filter), vilka klassificeras som farligt avfall. Det huvudsakliga syftet med arbetet bakom denna avhandling var att klarlägga bildnings- och kloreringsvägarna för dioxiner och dioxin-lika föreningar i temperaturintervallet 640-200°C i rökgaser från sopförbränning. Detta kan möjliggöra lösningar för ytterligare emissionsminskningar och en avgiftning av biprodukterna från avfallsförbränning, vilket minskar eller till och med eliminerar behovet av kostsam och riskfylld efterbehandling. Realistiska och välkontrollerade försök har utförts i en lab-skalereaktor där en artificiell hushållssopa har förbränts. En jämförelse av fyra olika temperatur- och uppehållstidsprofiler visade att bildning av polyklorerade dibenso-p-dioxiner (PCDD) och dibensofuraner (PCDF) sker snabbt och huvudsakligen inom temperaturintervallet 640-400°C. Bildningen var starkt beroende av en tillräckligt lång uppehållstid inom ett visst temperaturområde. En förlängd uppehållstid vid höga temperaturer (>450°C) resulterade i minskade halter av PCDD, vilka förhöll sig låga även senare i efterförbränningszonen. Isomermönstren av PCDD, PCDF och PCN (polyklorerade naftalener) visade alla tecken på att härröra från både klorfenolkondensation och kloreringsreaktioner. PCDD-mönstret visade tydliga indikationer på bildning från klorfenoler, och till mindre grad bildning via klorering. För PCDF var klorsubstitution i positioner angränsande till syrebryggan missgynnad, vilket bekräftades av multivariat modellering (O2PLS). Den variabel som starkast påverkade bildningen av PCDD var relativa fria energin (RΔGf). Modellerna visade på en distinkt gruppering av PCDD- och PCDF-kongenerna i två eller tre grupper för varje kloreringsgrad, och föreslås vara relaterad till sannolikheten för respektive kongen att bildas via klorfenolkondensation. Injektion av aromatiska kolstrukturer i rökgaskanalen gav upphov till skilda effekter. Injektion av naftalen ökade bildningen av monoklorerad naftalen medan resterande homologer inte verkade påverkas, sannolikt på grund av för kort uppehållstid för ytterligare klorering. Dibenso-p-dioxin spjälkades sannolikt till fenoliska fragment som klorerades och sedan återkondenserades till PCDD och PCDF, medan dibensofuran och fluoren kraftigt reducerade PCDD-koncentrationerna.

APA, Harvard, Vancouver, ISO, and other styles

2

Ryu, Jae-Yong. "Dioxin formation on copper (II) chloride from chlorinated phenol, dibenzo-p-dioxin and dibenzofuran precursors." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19050.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Gao, Qiuju. "Dioxins and dioxin-like compounds in thermochemical conversion of biomass : formation, distribution and fingerprints." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-118861.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

4

Wirsing, Johann Michael. "Toxikokinetische Betrachtungen zu 2,3,7,8-Tetrachlordibenzo-p-dioxin." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960376666.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Lindebro, Maria. "Mechanisms of regulation of dioxin receptor function /." Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-231-0/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Högberg, Pi. "Disruption of vitamin A metabolism by dioxin /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-608-1/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Carpi, Donatella. "Effect of dioxin on bone cell proteome." Thesis, Open University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495997.

Full text

Abstract:

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) Is an endocrine disrupting environmental pollutant that affects bone tissue, although the mechanistic basis of such effect is far from clear. In this study a proteomic approach has been adopted to Investigate the disturbance of the osteogenic process evoked by TCDD In an in vitro osteoblast differentiation model of rat mesenchymal stem cells. Stem cells were isolated from bone marrow of femurs and tibias of rats. Progress of osteoblastic differentiation was monitored by measuring mRNA expression levels of differentiation markers from control and TCDD-treated cells after 3,7 and 10 days of culture In presence and absence of TCDD using quantitative RT-PCR.

APA, Harvard, Vancouver, ISO, and other styles

8

Cantrell, Susannah M. "Embryotoxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924870.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Gagnon, Melanie Line. "Mutagenicity and dioxin-like activity of biodiesel emissions." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27980.

Full text

Abstract:

Diesel emissions have been shown to elicit a variety of toxicological effects, and alternative fuels (i.e., biodiesel) are currently being assessed to determine their ability to reduce the risks of adverse health effects. Exhaust emissions were generated using ULSD and biodiesel blended fuels and extracts of diesel PM (i.e., filters and PUFs) were separated into polar aromatic and non-polar neutral compounds. Mutagenic activity was assessed using the Salmonella mutagenicity assay, and Ah-receptor agonism was assessed using the DRCALUX assay. Results indicate that organic extracts of diesel/biodiesel particles contain direct- and indirect-acting polar aromatic mutagens as well as polar and non-polar Ah-receptor agonists. The mutagenicity of direct-acting compounds decreases with increasing concentrations of biodiesel in the fuel; however, there is no change in the indirect-acting mutagenicity. Furthermore, the ability of polar and non-polar compounds to induce the Ah-receptor increases with increasing concentrations of biodiesel in the fuel. These results provide an initial framework for evaluating the toxicological hazards of biodiesel emissions.

APA, Harvard, Vancouver, ISO, and other styles

10

Stinchcombe, Stefan. "Mechanismen der Dioxin-vermittelten Tumorpromotion in der Nagerleber /." Wannweil : S. Stinchcombe, 1996. http://www.gbv.de/dms/bs/toc/215104293.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Danielsson, Conny. "Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-963.

Full text

Abstract:

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of struc-turally related chlorinated aromatic hydrocarbons, generally referred to as “dioxins” are of great concern due to their extreme toxicity and presence in all compartments of the environment. Since they occur at very low levels, their analysis is complex and challenging, and there is a need for cost-efficient, reliable and rapid analytical alternatives to the expensive methods in-volving use of gas chromatography high-resolution mass spectrometry (GC-HRMS). It is im-portant to routinely monitor food and feed items to detect contaminations at an early stage. For the regulation of dioxins and dioxin-like PCBs in food and feed according to current legis-lation, large numbers of samples have to be analysed. Furthermore, soils at many industrial sites are also contaminated with dioxins and need remediation. In order to optimize the cost-efficiency of reclamation activities it is important to acquire information about the levels and distribution of dioxins in the contaminated areas. The aim of the studies underlying this thesis was to investigate the potential of comprehen-sive two-dimensional gas chromatography with a micro-electron capture detector (GC × GC-µECD) as a cost-effective method for analysing dioxins and dioxin-like PCBs in food, feed, fly ash and contaminated soils. Quantification studies of dioxins and dioxin-like PCBs were con-ducted and results were compared with GC-HRMS reference data. Generally, there was good agreement between both the congener-specific results and data expressed as total toxic equiva-lents (TEQs). The developed GC × GC-µECD method meets the European Community (EC) requirements for screening methods for control of dioxins and dioxin-like PCBs in food and feed. The presented results also indicate that GC × GC-µECD has potential to be used as a routine method for the congener-specific analysis of 2,3,7,8-PCDD/Fs and dioxin-like PCBs in matrices such as food and feed, fly ash and soil. However, to fully exploit the potential of the GC × GC-µECD technique, it should be combined with a fast and cost-efficient sample preparation procedure. Therefore, a number of certified reference materials (CRMs) were extracted using a new shape-selective pressurized liquid extraction technique with integrated carbon fractionation (PLE-C), and the purified extracts were analysed for PCDD/Fs using GC × GC-µECD. The results compared well with the certified values of a fly ash and a sandy soil CRM, but they were much too high for a com-plex clay soil CRM. It was concluded that this combination of techniques was very promising for screening ash and highly permeable soils. Further assessments and method revisions are still required before GC × GC-µECD can be used on a routine basis, and available software packages need to be refined in order to accelerate the data-handling procedures, which currently restrict the sample throughput.

APA, Harvard, Vancouver, ISO, and other styles

12

Danielsson, Conny. "Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection /." Umeå : Department of Chemistry, Environmental Chemistry, Umeå University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-963.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Tran, Thi Tuyet Hanh. "Environmental health risk assessment of dioxin in foods and the sustainability of public health interventions at severe dioxin hot spots in Vietnam." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/84905/1/Thi%20Tuyet%20Hanh_Tran_Thesis.pdf.

Full text

Abstract:

This study assessed environmental health risk from dioxin in foods and sustainability of risk reduction programs at two heavily contaminated former military sites in Vietnam. The study involved 1000 household surveys, analysis of food samples and in-depth discussions with residents and officials. The findings indicate that more than 40 years after the war, local residents still experience high exposure to dioxin if they consume local high risk foods. Public health intervention programs were rated moderately to well sustained. Internal migration, and lack of clear, official guidance and sensitivity regarding dioxin issues were the main challenges for sustainability of prevention programs.

APA, Harvard, Vancouver, ISO, and other styles

14

Bunge, Michael. "Dioxin-dechlorierende Bakterien in anaeroben Kulturen aus kontaminierten Flusedimenten." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974119725.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Tsang, Jennifer Arr, and 曾昭雅. "Dioxin contamination in soil: remediation technology and environmental management." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31255644.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Ashley, Claire M. "Toxicology of dioxin in an invertebrate, Pacifastacus leniusculus (Dana)." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283656.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Maliji, Ghorban. "Immunotoxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the rat." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319022.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Hamilton, James A. (James Andrew). "The influence of environmental justice on the dioxin controversy." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39383.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Thompson, Zachary John. "Statistical Estimation of Physiologically-based Pharmacokinetic Models: Identifiability, Variation, and Uncertainty with an Illustration of Chronic Exposure to Dioxin and Dioxin-like-compounds." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4241.

Full text

Abstract:

Assessment of human exposure to environmental chemicals is inherently subject to uncertainty and variability. There are data gaps concerning the inventory, source, duration, and intensity of exposure as well as knowledge gaps regarding pharmacokinetics in general. These gaps result in uncertainties in exposure assessment. The uncertainties compound further with variabilities due to population variations regarding stage of life, life style, and susceptibility, etc. Use of physiologically-based pharmacokinetic (PBPK) models promises to reduce the uncertainties and enhance extrapolation between species, between routes, from high to low dose, and from acute to chronic exposure. However, fitting PBPK models is challenging because of a large number of biochemical and physiological parameters to be estimated. Many of these model parameters are non-identifiable in that their estimates cannot be uniquely determined using statistical criteria. In practice some parameters are fixed in value and some determined through mathematical calibration or computer simulation. These estimated values are subject to substantial uncertainties. The first part of this paper illustrates the use of iteratively-reweighted-nonlinear-least-squares for fitting pharmacokinetic (PK) models, highlighting some common difficulties in obtaining statistical estimates of non-identifiable parameters and use bootstrap confidence interval to quantify uncertainties. Statistical estimation of parameters in physiologically based pharmacokinetic (PBPK) models is a relatively new area of research. Over the past decade or so PBPK models have become important and valuable tools in risk assessment as these models are used to describe the absorption, distribution, metabolism, and excretion of xenobiotics in a biological system such as the human or rat. Because these models incorporate information on biological processes, they are well equipped to describe the kinetic behaviors of chemicals and are useful for extrapolation across dose routes, between species, from high-to-low-doses, and across exposure scenarios. A PBPK model has been developed based on published models in the literature to describe the absorption, distribution, metabolism, and excretion of Dioxin and dioxin like compounds (DLCs) in the rat. Data from the National Toxicology Program (NTP) two year experiment TR-526 is used to illustrate model fitting and statistical estimation of the parameters. Integrating statistical methods into risk assessments is the most efficient way to characterize the variation in parameter values. In this dissertation a Markov Chain Monte Carlo (MCMC) method is used to estimate select parameters of the system and to describe the variation of the select parameters.

APA, Harvard, Vancouver, ISO, and other styles

20

Furness, Sebastian George Barton. "Novel mechanisms for activation of the dioxin (Aryl-hydrocarbon) receptor /." Title page, table of contents and summary only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phf988.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Petrulis, John R. "Mechanistic studies of the interactive toxicology of dioxin-like compounds." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ35811.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Shoven, Heather A. "Monitoring Dioxin Levels in Maine Rivers with Semipermeable Membrane Devices." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/ShovenHA2001.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Kazlauskas, Arunas. "Regulation of dioxin receptor function by the Hsp90 chaperone complex /." Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-176-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Öberg, Mattias U. L. "Health risk assessment of dioxin-like compounds in complex samples /." Stockholm : Karolinska inst, 2003. http://diss.kib.ki.se/2003/91-7349-692-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Hill, Adrian James. "Embryonic and larval responses to dioxin exposure in teleost fish." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272721.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Yeung, Chiu Wai. "Neurotoxicological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on cultured neurons." HKBU Institutional Repository, 2004. http://repository.hkbu.edu.hk/etd_ra/529.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Zhang, Qi. "The study of novel dioxin antagonist-euxanthone and its derivatives." HKBU Institutional Repository, 2003. http://repository.hkbu.edu.hk/etd_ra/507.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Leblanc, Alix. "Effets d’un mélange de polluants organiques persistants sur le métabolisme hépatique." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05P629/document.

Full text

Abstract:

Des études épidémiologiques ont montré que l’exposition à certains xénobiotiques est associée à une augmentation de la prévalence des maladies métaboliques. L’Homme est exposé à des mélanges de xénobiotiques de manière chronique et inévitable. Nous avons étudié les effets de l’interaction de deux xénobiotiques sur le métabolisme du foie, organe majeur de détoxification de l’organisme. Nous avons choisi deux perturbateurs endocriniens et polluants organiques persistants, qui activent des voies de signalisation différentes: la 2, 3, 7, 8 tétrachlorodibenzo-p-dioxine (TCDD), agissant via le récepteur aux hydrocarbures aromatiques (AhR), et l’α-endosulfan, un pesticide organochloré, qui peut agir via la voie du récepteur aux oestrogènes (ER) ou du récepteur X aux pregnanes (PXR). Notre objectif est de déterminer l’effet du mélange de ces polluants par rapport à chaque polluant isolé sur la régulation de certaines voies du métabolisme hépatique in vitro dans la lignée hépatocytaire humaine, HepaRG. Dans une première publication, une étude du transcriptome de cellules HepaRG différenciées a été effectuée. Ces cellules ont été exposées pendant 30 heures à 25nM de TCDD, 10μM d’α-endosulfan, ou au mélange. Nous avons observé que le mélange inhibe fortement l’expression de certains gènes impliqués dans le métabolisme glucidique et dans celui des alcools. Dans une seconde étude, nous avons donc étudié le mécanisme d’action du mélange sur le métabolisme glucidique. L’expression de deux gènes de la néoglucogenèse hépatique, le transporteur de glucose 2 (Glut2) et la glucose 6 phosphatase (G6Pc), est réduite de plus de 80% par le mélange. L’expression d’autres gènes du métabolisme glucidique (pyruvate kinase, glycogène synthase, glycogène phosphorylase, pyruvate déhydrogénase 2) est aussi diminuée, suggérant que le mélange peut affecter ce métabolisme de manière significative. De plus, la production de glucose diminue de 80% avec le mélange dans des conditions néoglucogéniques. En condition glycolytique, l’oxydation du glucose en CO2 diminue de 30% après 72 heures d’exposition au mélange. Un traitement à plus long terme (8 jours) avec des doses plus faibles des polluants (0.2 à 5nM de TCDD, 3μM d’α-endosulfan) diminue aussi l’expression de la G6Pc et de Glut2. Nous avons montré que la TCDD active bien la voie du AhR, et que le ER est impliqué dans l’action de l’α-endosulfan. Dans la troisième partie de cette thèse, nous avons étudié la régulation de plusieurs enzymes impliquées dans le métabolisme de l’alcool (alcool déshydrogénases, ADHs, cytochrome P450 2E1, CYP2E1) après l’activation du AhR. Les agonistes du AhR entrainent la diminution de l’expression des ARNm des ADH1, 4, 6 et du CYP2E1 et des protéines correspondantes. Nous avons montré que cette régulation utilise la voie génomique du AhR. De plus, cet effet est également observé après traitement de 8 jours par de faibles doses de TCDD. L’exposition chronique de l’Homme à de faibles doses de xénobiotiques en mélange pourrait affecter le métabolisme glucidique hépatique et contribuer, en partie, au développement du syndrome métabolique
Epidemiological studies have shown that exposure to certain xenobiotics is associated with an increased prevalence of metabolic diseases. Humans are exposed to mixtures of xenobiotics in a chronic and inevitable way. We studied the effects of the interaction of two xenobiotics on metabolism in the liver, the major organ for detoxification in the body. We chose two endocrine disruptors and persistent organic pollutants which activate different signaling pathways: 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), which uses the AhR (Aryl hydrocarbon receptor) pathway, and α-endosulfan, an organochlorine pesticide, which acts via the PXR (pregnane X receptor) and/or the ER (estrogen receptor) pathway. Our aim was to determine the effects of this pollutant mixture, as compared to each pollutant alone, on the regulation in vitro of some hepatic metabolism pathways in the human hepatic cell line, HepaRG. In the first publication, a transcriptomic study of differentiated HepaRG cells was performed. The cells were exposed for 30h to 25nM TCDD, to 10 µM α-endosulfan or to the mixture. We observed that the mixture strongly inhibited the expression of some genes involved in the metabolism of glucose and alcohol. In the second study, we studied the mechanism of action of the mixture of pollutants on the metabolism of glucose. The expression of two genes involved in hepatic gluconeogenesis, glucose transporter 2 (GLUT2) and glucose-6-phosphatase (G6Pc), were reduced 80% by the mixture. The expression of other glucose metabolism genes (pyruvate kinase, glycogen synthase, glycogen phosphorylase, pyruvate dehydrogenase 2) also was decreased suggesting that the mixture might impact markedly carbohydrate metabolism. Furthermore, glucose production decreased 40% with the mixture under gluconeogenic conditions. Under glycolytic conditions, the oxidation of glucose into CO2 decreased 30% after 72h of exposure of the cells to the mixture. Long-term treatment (8 days) with lower doses (0.2 to 5 nM TCDD, 3 µM α-endosulfan) similarly decreased G6Pc and GLUT2 expression. We showed that TCDD activated the AhR pathway, and that ER was partly involved in the α-endosulfan effect. In the third part of this thesis, we studied the regulation of several enzymes involved in the metabolism of alcohol (alcohol dehydrogenase, ADH, cytochrome P450 2E1, CYP2E1) after activation of AhR. AhR agonists led to a decrease in the amounts of mRNAs for ADH1, 4, 6 and CYP2E1 and the corresponding proteins. We showed that this regulation uses the AhR genomic pathway. Furthermore, this effect was also observed after 8 days of treatment with lower doses of TCDD. Chronic exposure of individuals to low doses of xenobiotics in mixtures might significantly affect hepatic carbohydrate metabolism and be a contributing factor for the development of the metabolic syndrome

APA, Harvard, Vancouver, ISO, and other styles

29

Hajizadeh, Yaghoub. "Influence of PAH, SO2 and NH3 on Dioxin Formation, and the Effectiveness of Waste Derived Activated Carbons on Control of Dioxin Emissions from Waste Incineration." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534431.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

GUILBOT, Kelly. "Determination of dioxins in Cretaceous strata from the South of Sweden. : Can the environmental anthropogenic pollutant dioxin be of natural origin ?" Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-25916.

Full text

Abstract:

Eleven sediment samples from different geological layers and four fossils from the South of Sweden were collected and estimated to be 80 million years old (approximately late of Cretaceous period). The samples were analyzed for polychlorinated dibenzo-p dioxins (PCDD/Fs) to investigate whether these samples are likely to contain dioxins from a natural formation. For over thirty years, the scientific community has discussed the possibility of a natural formation of dioxins. Several hypothesis have been put forward, but often rejected by the evidence of a source of anthropogenic pollution in the samples. In order to answer this issue, two types of analyses have been performed : high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) and elemental analyzer-isotopic ratio mass spectrometry (EA-IRMS). HRGC/HRMS provides information about the source of dioxins comparing the distribution of all PCDD/Fs to experimental isotopic patterns from past publications. δ13C of organic carbon gives information about the nature of carbon present in soils and can be helpful to trace paleoclimates.

APA, Harvard, Vancouver, ISO, and other styles

31

Kolluri, S. K. [Verfasser]. "Search for Ah (dioxin) receptor target genes which mediate dioxin toxicity: induction of P27sup(k)ⁱsup(p)¹ cell cycle inhibitor and N-myristoyltransferase2 / S. K. Kolluri." Karlsruhe : KIT-Bibliothek, 1999. http://d-nb.info/1198220112/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Herve, Jessica. "Cytochrome P4501A induction by dioxin-like compounds in avian hepatocyte cultures." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28333.

Full text

Abstract:

In this study, the potencies of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 2,3,7,8-tetrachlorodibenzofuran (TCDF) to induce cytochrome P4501A (CYP1A) were determined. The concentration-dependent effects of TCDD, PeCDF and TCDF on ethoxyresorufin O-deethylase (EROD) activity, CYP1A4 mRNA and CYP1A5 mRNA expression were measured in primary hepatocyte cultures of chicken (Gallus gallus), ring-necked pheasant (Phasianus colchicus), Japanese quail (Corturnix japonica ), and herring gull (Larus argentatus) embryos exposed for 24h. The results demonstrated that PeCDF was as potent as TCDD to induce CYP1A in chicken hepatocytes, but that PeCDF was more potent than TCDD in ring-necked pheasant, Japanese quail and herring gull hepatocytes. Moreover, the chicken was the most sensitive species to CYP1A induction by TCDD or TCDF, but all species were approximately equisensitive to CYP1A induction by PeCDF. Together these results showed that all species do not respond the same way to different DLCs, suggesting that interactions between a DLC and a species are structure- and cell type-dependent. These results raise interesting questions concerning the molecular mechanism of action of DLCs and the toxic equivalency factors that are broadly assigned to all avian species.

APA, Harvard, Vancouver, ISO, and other styles

33

Lees, Michael. "Characterising the mechanism of activation of the bHLH/PAS Dioxin Receptor /." Title page, summary and contents only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phl4873.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Ward, David Barry. "The detoxification of dioxin contaminated APC residue by energy efficient sintering." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370082.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Rebourcet, Diane. "Caractérisation des effets d'une exposition in utéro à la dioxine sur le système reproducteur du rat : identification de gènes cibles testiculaires : implication du récepteur AHR dans la physiologie testiculaire de la souris." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10077.

Full text

Abstract:

L'homme de par son environnement se trouve exposé de manière chronique à un mélange de substances faiblement dosées. Cette exposition est particulièrement préoccupante pour la santé humaine. En effet, certaines substances sont susceptibles d'interagir et de perturber le système endocrinien, ce sont les perturbateurs endocriniens (PE). Les dioxines, appartenant aux PE, sont des sous-produits non désirés d'un grand nombre de procédés industriels. Les données de la littérature décrivent un impact des dioxines sur le développement et la fonction de reproduction des mâles, cependant les mécanismes d'action ne sont pas totalement élucidés. Les travaux présentés dans ce manuscrit ont porté sur la mise en évidence des effets d'une exposition in utero à la TCDD sur l'appareil reproducteur mâle et sur l'identification de marqueurs d'exposition au niveau testiculaire chez le rat. Nous montrons une baisse transitoire des réserves spermatiques chez le jeune adulte, ce défaut disparaît chez l'animal adulte. Par ailleurs, si peu de gènes s'avèrent différentiellement exprimés dans le testicule après une exposition, nous mettons en évidence que deux chémokines Ccl5 (régulé négativement) et Cxcl4 (stimulé) pourraient être de bons marqueurs d'exposition. Nous avons reproduit ces effets in vitro dans des cultures primaires de cellules de Leydig de souris adultes. En parallèle, les effets de cette exposition à la dioxine ont été analysées chez les femelles (S. Magre). La dioxine étant un PE, nous avons comparé les profils transcriptomiques de testicules et d'ovaires afin de mettre en évidence les gènes communs ou sexe-spécifiques. Nous présentons également la caractérisation du phénotype de l'appareil reproducteur mâle de souris invalidée pour le récepteur aryl hydrocarbone (AhR). L'étude de la physiologie du testicule au cours du développement et des réserves spermatiques et deux analyses transcriptomiques testiculaires ont ainsi été initiées
Mankind and wildlife are exposed chronically and at low doses to a cocktail of substances. Studies of these molecules are of major concern, as some have shown ability to interact and disrupt endocrine system. Dioxins are undesired by-products of combustion processes originating from industrial activity. Its impact on development and male reproduction has been documented in many studies. However its mechanism of action is still not clearly understood. Data described in this manuscript highlights the effect of an in utero exposure to TCDD on male reproductive function. Dioxin induced a decrease of spermatic reserve in the young adult. This defect was transitory as adult showed normal reserve. Next, we identified sensitive dioxin genes differentially expressed in testes. Beside few genes differentially expressed, we identified 2 chemokines : Ccl5, down-regulated and Cxcl4, up-regulated. Ccl5 is expressed in Leydig cells whereas Cxcl4 is found in both Leydig and Sertoli cells. This result is confirmed by an in vitro study. Dioxin impact on female reproductive function was also studied (S. Magre). As dioxin is an endocrine disruptor, we initiated the identification of common or sex-specific gene in ovaries and testis exposed in utero. To do so, we compared transcriptomic profile of these 2 tissues focusing on chemokine and cytochrome gene expression pattern. Herein is also presented the results concerning the reproductive phenotype of male knocked-out (KO) for AhR. Testicular physiology and spermatic reserve were examined and two transcriptomic analyses were achieved

APA, Harvard, Vancouver, ISO, and other styles

36

Hedman, Björn. "Dioxin emissions from small-scale combustion of bio-fuel and household waste." Doctoral thesis, Umeå University, Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-593.

Full text

Abstract:

Denna avhandling behandlar rökgasutsläpp av persistenta organiska föroreningar, framförallt dioxiner, vid förbränning av fasta biobränslen och torrt hushållsavfall i relativt små anläggningar (5-600 kW) utan avancerad rökgasreningsteknik.

Samförbränning av avfall och biobränsle i effektiva mindre biobränslepannor testades som en alternativ strategi till den vanligen förekommande storskaliga hanteringen och förbränningen fast hushållsavfall. Medan storskalig förbränning av avfall ger investeringsmässiga fördelar med rökgasreningsteknik etc. kan små lokala anläggningar ha transportmässiga fördelar och möjligheter till utnyttjande av lokala biobränsletillgångar. Källsorterat, torrt, brännbart hushållsavfall insamlades från hushåll i glesbygd och samförbrändes i brikettform med energigräset rörflen i 150-600 kW biobränslepannor. Endast undantagsvis understeg dioxinemissionerna gällande gränsvärden för avfallsförbränning och nivåerna av väteklorid i rökgas översteg gränsvärdena flerfaldigt. Det bedömdes att någon form av extra rökgasrening är nödvändig för att säkerställa nivågränserna. Dioxiner hittades också i det eldade avfallet, framförallt i textilfraktionen. Dioxinmängderna i rökgaserna var oftast lägre än i det ingående bränslet.

Intermittent pelletseldning gav oväntat höga utsläpp av dioxiner med en emissionsfaktor på 28 ng(WHO-TEQ)/kg. Vedeldning i en modern miljömärkt villapanna gav betydligt lägre utsläpp av dioxiner än eldning i en gammal kombipanna och eldning med full lufttillförsel, som kan jämföras med användning av ackumulatortank, resulterade i upp till 90% minskning av utsläpp av dioxiner jämfört med eldning med reducerat lufttillskott (’pyreldning’). Eldning av plastavfall i en vedpanna gav höga utsläpp av dioxiner.

Okontrollerad förbränning av trädgårdsavfall och hushålls avfall i tunna eller som öppen eld ’bakgårdsbränning’, gav stora variationer i utsläppsnivåer som bara delvis kunde kopplas till avfallsinnehåll. Resultaten visar att denna typ av förbränning kan vara en betydande källa till dioxiner i miljön, och ett emissionsfaktorintervall på 4-72 ng (WHO-TEQ)/kg föreslås för bedömningar av utsläpp från backgårdsbränning av avfall med låga eller måttliga klorhalter.

En sammanfattande slutsats av alla försök är att dioxin utsläpp beror på komplicerade samband mellan bränsleinnehåll och förbränningsbetingelser. Bränslen med mycket höga klorhalter av ger oftast högre utsläpp av dioxiner än bränslen med låga klorhalter medan små skillnader döljs av variationer i förbränningsbetingelser.

This thesis deals with emissions of persistent organic pollutants, primarily dioxins, from the combustion of solid biofuels and dry combustible household waste in relatively small facilities, 5-600 kW, without advanced air pollution controls.

Co-combustion of waste and biofuel in effective small boilers was tested as an alternative to prevailing large-scale management and combustion strategies for handling municipal solid waste. This approach includes no advanced air pollution control systems, but offers two advantages: limiting transport and providing scope to use local biofuel resources. Source-sorted, dry, combustible household waste was collected from households in a sparsely populated area and co-combusted as briquettes together with reed canary-grass in 150-600 kW biofuel boilers. Most trials showed difficulties to meet regulative limits for the emissions of dioxins valid for incineration of MSW and the regulated limits for emissions of hydrochloric acid were exceeded manifold. It was concluded that additional flue-gas cleaning will be needed to ensure that emissions are sufficiently low. Dioxins were also found in the waste, especially in the textile fraction. The mass of dioxins in the flue-gas emissions was generally lower than the mass in the fuel input.

Intermittent combustion of wood pellets in a residential boiler resulted in an unexpectedly high dioxin emissions factor of 28 ng (WHO-TEQ)/kg fuel. Combustion of wood in a modern environmentally certified boiler yielded considerably lower dioxin emissions than combustion in an old boiler, and combustion with a full air supply, i.e. with use of heat storage tank, resulted in up to 90% reductions in dioxin emission factors compared to combustion with reduced air supply. Combustion of plastic waste in a residential wood boiler resulted in high emissions of dioxins.

Tests of uncontrolled combustion of garden and household waste in barrels or open fires, ‘backyard burnings’, resulted in emissions with large variations that could only be partly correlated to the waste constituents. The results imply that this may be an important source of dioxins in the environment and an emission factor range of 4-72 ng (WHO-TEQ)/kg is suggested for estimating emissions from backyard burnings of lightly and moderately chlorine-contaminated waste.

A summarized conclusion from all of the experiments is that predicting emission levels from waste contents is not straightforward (except that fuels with very high chlorine levels will usually result in high levels of dioxins in flue-gas emissions). Moderate differences in chlorine levels will usually be masked by the effect of variations in combustion conditions.

APA, Harvard, Vancouver, ISO, and other styles

37

Lundgren, Kjell. "Properties and analysis of dioxin-like compounds in marine samples from Sweden." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-24.

Full text

Abstract:

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) have been assigned toxic equivalency factors (TEFs). These compounds are today routinely analysed with sophisticated analytical techniques. In a near future, there might be other dioxinlike compounds such as polychlorinated naphthalenes (PCNs), alkyl-polychlorodibenzofurans (R-PCDFs), and polychlorinated dibenzothiophenes (PCDTs) added to this list of toxic dioxin-like compounds. It is therefore important to have a readiness to analyse these new compounds in environmental samples. In this study, a multi-residue non-destructive analytical method for the analyses of these planar dioxin-like compound classes was developed. The use of HPLC PX-21 carbon column fractionation enabled the separation of interfering PCBs from coplanar PCBs and other planar dioxin-like compounds of interest. The obtained planar fraction containing the dioxin-like compounds was analysed using high-resolution GC-MS. Levels of PCNs in surface sediments and settling particulate matter in the northern Baltic Sea were determined. The concentrations of PCNs in background surface sediments were approximately 1 ng/g dw and the estimated PCN fluxes were similar to the pre-industrial levels determined in Europe. The PCN congener patterns in the surface sediments suggest that the PCNs deposited in the Baltic Sea originate from similar sources. Bioaccumulation of PCNs in a benthic food chain (sediment, amphipod, isopod, and four-horned sculpin) from the Gulf of Bothnia was studied. The results indicated that only a few PCN congeners biomagnified. The highest biomagnification factors (BMFs) were found for 2,3,6,7-substituted congeners and those lacking adjacent hydrogen-substituted carbon atoms. The calculated biota to sediment accumulation factors (BSAFs) showed that the tetra- and penta- CNs exhibited BSAF values higher than one, while BSAFs for the more chlorinated PCNs were less than one. A general difference between the northern and southern parts of the Gulf of Bothnia could be seen in the samples, with the lowest PCN and total PCB concentrations being found in the north and the highest in the south. This gradient is related to distance from the more industrialised and populated regions in the southern parts of Sweden and Finland, and central Europe. Analysis of R-PCDFs in crustacean samples from the Swedish west coast was performed using HRGC-MS/MS. The ΣR-PCDFs in these samples were present at concentrations up to 10 times higher than the ΣPCDFs. The relatively high concentrations of R-PCDFs in the crab samples demonstrate that these compounds bioaccumulate. The fate of a pollutant in the environment and the toxicity of a compound are governed by its physicochemical properties. The information found in a data set of properties can predict a compound’s mode of action. The following physicochemical properties for 87 PCDFs were measured: ultra-violetadsorption, relative retention times on two common gas chromatographic stationary phases, and relative mass spectrometric response factors using EI- and NCI- modes.

APA, Harvard, Vancouver, ISO, and other styles

38

Kümmling, Karen Elizabeth. "Dioxin and furan concentrations in Fraser River and Fraser River Estuary sediment." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ35904.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Hedman, Björn. "Dioxin emissions from small-scale combustion of bio-fuel and household waste /." Umeå : Department of Chemistry, Umeå University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-593.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Yeager, Ronnie Lee. "Red light therapy an innovative approach to attenuating dioxin-induced embryo toxicity /." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3264315.

Full text

Abstract:

Thesis (Ph.D.)--Indiana University, Dept. of Environmental Science, 2007.
Source: Dissertation Abstracts International, Volume: 68-05, Section: B, page: 2924. Adviser: Diane S. Henshel. "Title from dissertation home page (viewed Jan. 24, 2008)."

APA, Harvard, Vancouver, ISO, and other styles

41

Chu, Po-han, and 朱柏翰. "Using PCP and dioxin to induce dioxin-degrading genes expression in Pseudomonas mendocina NSYSU." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/85253034491475450798.

Full text

Abstract:

碩士
國立中山大學
生物科學系研究所
104
Pseudomonas mendocina strain NSYSU was isolated from a dioxin-contaminated soil in 2002. Previous studies showed that this strain could degrade various dioxins under aerobic and anaerobic conditions. We also found the efficiency of dioxin-degrading could be enhanced after pentachlorophenol (PCP) inducing. Preliminary studies showed that P. mendocina NSYSU might contain nine dioxin-degrading genes including dechlorination and ring-cleavage genes. Therefore in this study, we used real-time PCR to detect the expression of these dioxin-degrading genes after inducing by PCP, OCDD, and OCDF. The results showed P. mendocina NSYSU contains two ring-cleavage genes (Pmen_0474, Pmen_2526) and five dechlorination genes (Pmen_0392, Pmen_1621, Pmen_3718, Pmen_4219, Pmen_4457). The PCP induction study revealed that the expression of these 7 dioxin-degrading genes boosted 5.58 folds at 0.5~5.5 hours after inducing by 40 ppm PCP. The OCDD induction study showed that the expression of these 7 dioxin-degrading genes increased 3.69 folds at 10~14.5 hours after inducing by 0.1 ppm OCDD. For the OCDF induction study, the results showed that the expression of these 7 dioxin-degrading genes slightly increased 1.79 folds at 11~15 hours after inducing by 0.1 ppm OCDF. In summary, the expression of all these 7 dioxin-degrading genes was successfully induced by PCP, OCDD and OCDF under aerobic conditions, in which PCP performed the best induction effect.

APA, Harvard, Vancouver, ISO, and other styles

42

Wang, Yao-Chih, and 王耀志. "The concentration of dioxin in eggs and blood after dioxin exposure in laying poultry." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/2d2qkw.

Full text

Abstract:

碩士
國立屏東科技大學
動物科學與畜產系所
106
Dioxin-like compounds(DLCs) is an environmental contamination object. Produced through burning process and are highly lipophilicity. It cause bioaccumulation by entering the food chain. According to researches shows that the speed of dioxin decomposition in animals will be different with races, body fat content, breast feeding and laying eggs. But the correlation level should use other measure methods to ensure. The purpose of this research is to estimate the correlation between different poultry by measuring the dioxin concentration in blood and eggs of red-feathered chickens and brown Tsaiya ducks. In this trail we use two animals. In red-feathered chickens, dioxin group was fed with the dioxin contamination feed (5.17 ng TEQ/kg diet) for 14 days and the diet was replaced by clean diet for another 28 days. In brown Tsaiya ducks, dioxin group were fed one capsule (754 pg TEQ/per) daily for 14 days. Following 14 days, the trial continued without the feeding capsules until 70 days. In this trail we use these two data to run a cross match up, in order to ensure the correlation between different poultry of dioxin accumulation in blood and eggs. The results shows that in growth performance and laying frequency, both birds in abdominal weight shows a significant decrease (P < 0.05). In the result of blood biochemistry, brown Tsaiya ducks in total protein shows a significant decrease in dioxin group (P < 0.05). In the result of dioxin accumulation in blood between both poultry shows in 27.43 pg TEQ/g fat and 30.35 pg TEQ/g fat respectively. In the results of proportion of dioxin congeners shows in both birds are 4 and 5 chlorinated congeners took the major part, means that in both birds the low chlorinated congeners in blood will took the main proportion. In the results of dioxin bioconcentration factor shows in red-feathered chickens 5 and 6 chlorinated congeners has the higher BCF, and in Brown tsaiya ducks 6 chlorinated congeners has the higher BCF. It means both poultry has different sensitiveness to dioxin congeners. In the result of dioxin accumulation in blood between both poultry shows in 13.50 pg TEQ/g fat and 50.00 pg TEQ/g fat respectively. In the results of proportion of dioxin congeners shows in chickens is 4 and 5 chlorinated congeners took the major part, but in ducks is 6 chlorinated congeners took the major part. At last is the results of dioxin clearance rate shows the clearance rate will follow the days increase with an increase. By the day of 42, most of the congeners will reach 80% of clearance rate. To sum up the results, in this trail both of the birds will occur a significant loss in abdominal fat. Brown Tsaiya ducks compares to red-feathered chicken will have a higher sensitivity in blood biochemistry. In blood chickens will have a higher bioaccumulation in 5 and 6 chlorinated congeners, ducks is 6 chlorinated congeners. In eggs chickens will have a higher bioaccumulation in 6 chlorinated congeners, ducks is 4 and 5 chlorinated congeners. And the results of dioxin clearance rate both birds shows lower level in low chlorinated congeners.

APA, Harvard, Vancouver, ISO, and other styles

43

Allgeier, Sarah Hicks. "Dioxin and signaling pathways in prostate development." 2007. http://www.library.wisc.edu/databases/connect/dissertations.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Gong, Xin-cheng, and 龔信誠. "Isolation and characterization of dioxin biotransformation bacteria." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/94722977541780474015.

Full text

Abstract:

碩士
國立中央大學
環境工程研究所
98
The objective of this study was to isolate the indigenous dioxin-degrading bacteria of Taiwan. Also, the characteristics of these bacteria were investigated after isolation followed by culture enrichment and strains acclimation. Three soil samples were gathered from the downstream of the announced dioxin and contamination site. The analytical results of PCDDs/PCDFs and their isomer concentration in all samples confirmed the dioxin contamination of the sampling site with the highest total toxic equivalence of 2450 ng-TEQ/kg of the contaminants. Four bacteria strains which can survive in dioxin media were isolated after sub-culture inoculation. The four strains were identified as Achromobacter xylosoxidans, Ochrobactrum anthropi, Ralstonia mannitolilytica and Agromyces sp.. It was found that all of the strains are gram’s negative in the morphology. In addition, Ochrobactrum anthropi and Agromyces sp. demonstrated the largest configuration with length 2 μm and width 1 μm. Particularly, Agromyces sp. had closest relationship to the PCP-degrading bacterium Mycobacterium chlorophenolicum PCP-1 according to phylogenetic analysis (bootstrap value = 95). The microbial growth kinetics showed that Achromobacter xylosoxidans and Ochrobactrum anthropi had the maximum specific growth rate of 0.115 h-1. Ralstonia mannitolilytica had the smallest half-saturation constants of 43.2 mg/L, meaning least dependence of substrate. Ochrobactrum anthropi has the greatest substrate inhibition coefficient of 0.948 mg/L. However, the microbial growth tests revealed that adding extra carbon source of glucose (1000 mg/L) to the culture medium containing high dioxin concentration (10 μg/kg 2,3,7,8-TCDD) would decrease the growth inhibition. Achromobacter xylosoxidans, Ochrobactrum anthropi, Agromyces sp. could degrade 2,3,7,8-TCDD at lag phase, whereas Ralstonia mannitolilytica decomposed it primarily at log phase. It was also observed that Agromyces sp. had the maximum 2,3,7,8-TCDD degradation efficiency (97%). The results of proteome analysis suggested that two primary proteome molecular weight of 40 and 50kDa for Achromobacter xylosoxidans and Ochrobactrum anthropi had changed during degradation of 2,3,7,8-TCDD. By contrast, 120 kDa proteome of Ralstonia mannitolilytica as well as 20 and 120 kDa proteome of Agromyces sp. would increase when 2,3,7,8-TCDD was degraded.

APA, Harvard, Vancouver, ISO, and other styles

45

Lin, Yi-Chun, and 林奕鈞. "The Effect of Dioxin Exposure on Production Performance, Blood Biochemistry, Tissue Dioxin Distribution and Antioxidant Product of Brown Tsaiya Ducks." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/z8j6ty.

Full text

Abstract:

碩士
國立屏東科技大學
動物科學與畜產系所
105
Dioxin-like compounds are a group of toxic compounds that cannot be easily decomposed, can accumulate in the environment, and can cause bioaccumulation through the food chain. Studies on how dioxin-like compounds are metabolized in ducks have been conducted rarely. Therefore, the purpose of the present study was to explore the effect of oral intake of dioxin like compounds on the production performance, blood biochemistry, dioxin bioaccumulation in tissues, and antioxidant contents in eggs and liver of Brown Tsaiya ducks. In present experiment, 50 Brown Tsaiya ducks at 25 weeks old age had been randomly assigned into control and dioxin groups. Ducks were given commercial feed 110 gram per day, water was provided ad libitum and the eggs were collected and weighed every day. In the first 14 days, ducks in the dioxin group were fed a dioxin capsule per day. At day 2, 14, 28, 42, and 70 after dioxin exposure, 5 ducks of each group were sacrificed. The liver, spleen, breast meat, thigh meat, and abdominal fat were removed and weighed. The production performance, blood biochemistry, dioxin bioaccumulation, and antioxidant contents in eggs and liver were conducted. The results showed that feed intake, laying frequency and egg weight presented non-significant difference among treatments. At whole experiment period the abdominal fat and thigh weight in dioxin group was significantly lower than the control group (P < 0.05). In dioxin group, the triglyceride concentration in blood was significantly higher than that in the control group in whole experiment period (P < 0.05). For dioxin distribution in tissues, the bioconcentration factor (BCF) was negatively correlated with the degree of chlorination. However, dioxin clearance rate was positively correlated with the degree of chlorination. The lipid peroxidation ability in liver showed that dioxin treatment did not significantly increase the TBARS content in liver than in the control group. However, in egg yolk dioxin treatment significantly increased the lipid peroxidation level (P < 0.05). The total GSH content in liver and eggs showed that dioxin treatment significantly increase the GSH content in liver, but in egg white dioxin treatment showed significantly lower the GSH content than in the control group(P < 0.05). The amount of vitamin E in egg yolk of Brown Tsaiya ducks at whole experiment period revealed significantly lower than in the control group (P < 0.05). To sum up, after dioxin exposure, the concentration of triglyceride in sera increased, the thigh weight decreased. The lipid peroxidation capacity and antioxidant contents in liver and eggs revealed that the concentration of TBARS showed no significant difference among dioxin and control groups in liver. However, in eggs, dioxin treatment significantly affected (P < 0.05) the TRARS, total GSH content and vitamin E concentration than in the control group.

APA, Harvard, Vancouver, ISO, and other styles

46

Moffat, Ivy D. "Mechanisms of Genetic Resistance To Dioxin-induced Lethality." Thesis, 2008. http://hdl.handle.net/1807/11119.

Full text

Abstract:

Dioxins are environmental contaminants that raise concern because they are potent and persistent. The most potent dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), causes a wide variety of biochemical and toxic effects in laboratory animals and in humans. Major toxicities of TCDD are initiated by their binding to the AH receptor (AHR), a ligand-activated transcription factor that regulates expression of numerous genes. However, the specific genes whose dysregulation leads to major toxicities such as wasting, hepatotoxicity, and lethality are unknown. The objective of this thesis research was to identify the molecular mechanisms by which dioxins cause lethality. To this end, a powerful genetic rat model was utilized – the Han/Wistar (Kuopio) rat which is highly resistant to dioxin toxicity due to a major deletion in the AHR’s transactivation domain (TAD) leading to 3 potential AHR variant transcripts. We found that insertion-variant transcripts (IVs) are the dominant forms of AHR expressed in H/W rats, constitutively and after TCDD treatment. Gene expression array analysis revealed that the total number of TCDD-responsive genes in liver was significantly lower in H/W rats (that carry the TAD deletion) than in dioxin-sensitive rats (that carry wildtype AHR). Genes that are well-known to be AHR-regulated and dioxin-inducible  such as CYP1 transcripts  remained responsive to TCDD in H/W rats; thus the TAD deletion selectively interferes with expression of a subset of hepatic genes rather than abolishing global AHR-mediated responses. Genes that differed in response to TCDD between dioxin-sensitive rats and dioxin-resistant rats are integral parts of pathways known to be disrupted by dioxin treatment such as protein synthesis/degradation, fatty acid transport/metabolism, and apoptosis. These genes are worthy candidates for further mechanistic studies to test their role in major dioxin toxicities. Numerous differentially-regulated genes were downregulated; however, microRNAs, which downregulate mRNA levels in other systems, likely play no role in downregulation of mRNAs by dioxins in adult liver and are unlikely to be involved in hepatotoxicity. Findings in this research support the hypothesis that H/W rats are resistant to TCDD lethality because the TAD deletion prevents the AHR from dysregulating specific mRNA transcripts but not hepatic miRNAs.

APA, Harvard, Vancouver, ISO, and other styles

47

Marcheterre, Line. "Fate of octachlorodibenzo-p-dioxin in small ponds." 1985. http://hdl.handle.net/1993/28753.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Chang, Yu-Hsin, and 張宇欣. "The Application of SOM on Dioxin Fingerprint Matching." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/11465123126965498405.

Full text

Abstract:

碩士
國立臺灣大學
環境工程學研究所
95
Nowadays, with fast development of industry in Taiwan, dioxin pollution events take place more often. The methods usually used for identifying pollution sources are bounded, and take a lot of time to analyze the results. To find out pollution sources effectively, a dioxin fingerprint matching model based on SOM Toolbox is built in this study. The half-lives of dioxin and the scenario of multiple pollution are also considered to investigate the influence of them on dioxin fingerprints. The main advantages of SOM dioxin fingerprint matching model are as follows: a) it is able to find out the dioxin pollution sources in the short time and from the limited information; b) by using U-matrix to visualize the SOM results, no other means are needed to help analyzing the topologies; c) there is no need to transform the variables to some linear functions, so that no information would be missed; and d) because of the concept of ‘neighborhood’, the spatial information of samples are displayed well. However, when there are more than two pollution sources, and the contribution of these sources are similar, SOM can’t identify exactly which the sources are. Moreover, the decay of dioxin in air, plants and soil doesn’t have any obvious influence on fingerprints, but it is the basis for judging whether there are only one or more than two pollution sources. On the other hand, the half-lives of dioxin in water and human blood are influential on fingerprints and may cause error of identifying pollution sources. As deduced from here, dioxin decay data and residence time in media both play very important roles in affecting the changes of dioxin fingerprints. As a result, the more local and complete decay data is gained, and the more specific the transportion of dioxin is known, the more accurate the dioxin fingerprint matching will be.

APA, Harvard, Vancouver, ISO, and other styles

49

Liao, Chen-yuan, and 廖振淵. "Degradation of Dioxin in Fly Ashes via Pyrolysis." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/64440340148960078514.

Full text

Abstract:

碩士
國立中央大學
環境工程研究所
98
The major fly ash sources in Taiwan include municipal solid waste incinerators (MSWIs), electric arc furnaces (EAFs) and secondary metal smelting processes. Because fly ashes contain high concentration of dioxin and heavy metal, they belong to hazardous waste and have to be treated before its releases. Fly ashes account for 62% of total hazardous industrial waste in Taiwan, and fly ashes are mostly treated with stabilization/solidification in Taiwan, resulting in the increase of fly ash volume. So how to efficiently lower the toxicity in fly ashes, reducing the stabilization/solidification fly ashes volume are the most important issue in Taiwan. This study is motivated to understand the fly ash characteristics and construct a pyrolysis system for degrading dioxins in the fly ashes. The fly ashes investigated in this study include municipal solid waste incinerators fly ashes, electric arc furnaces fly ashes, Waelz process fly ashes and secondary copper smelting fly ashes. The results show that the dioxin removal efficiency is higher as the reaction time gets longer or temperature gets higher. At 3 hour, 400oC, 100% nitrogen flow, the dioxin removal efficiency is 98.1% in MWI fly ashes, 26% in secondary copper smelting fly ashes, 72% in EAF fly ashes; it shows that MWI fly ash has the highest dioxin removal efficiency. The dioxin removal efficiencies do not change significantly whether the system contains the flow or not. Dioxin formation is observed when the flow contains 5% oxygen, and the secondary copper smelting fly ashes is of the highest formation. The dioxin removal efficiency achieved by adding Ca(OH)2 is higher than that of adding CaO.

APA, Harvard, Vancouver, ISO, and other styles

50

Lu, Jin Rong, and 呂進榮. "Analysis of dioxin related compound in environmental samples." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/67801529616294311089.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Dioxin'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles