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Gamboa, Nadia. "DDT, a historical review." Revista de Química, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/100129.
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El DDT está íntimamente vinculado al siglo XX. Su producción, uso y comercialización están prohibidos por ser un contaminante organoclorado persistente controlado por el Convenio de Estocolmo.DDT is closely linked to the twentieth century. Its production, use and marketing are now banned because it is a persistent organochlorine pollutant controlled by the Stockholm Convention.
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Leone, Andrea D. "Enantiomeric composition of Chiral pesticides in soil and air from the U.S. cornbelt region." Youngstown State University / OhioLINK, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=ysu997192215.
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McDougal, Rebecca, and n/a. "DDT residue degradation by soil bacteria." University of Otago. Department of Microbiology & Immunology, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070914.142931.
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1,1,1-trichloro-2,2-bis(4-chlorophenyl)-ethane (DDT) residues (DDTr) are widespread and persistent environmental contaminants, and have been classed as priority pollutants by the United Nations Environment Programme (UNEP). DDTr are potent endocrine disrupting molecules, and have been associated with reproductive abnormalities in juvenile alligators and rats. Microorganisms that metabolise DDTr both aerobically and anaerobically have been isolated and characterised. Bacteria that degrade DDTr aerobically typically utilise a dioxygenase to initiate degradative reactions through ring-hydroxylation, and convert DDTr to 4-chlorobenzoate without further degradation. Terrabacter sp. strain DDE-1 was isolated from DDTr-contaminated soil from Canterbury, New Zealand, and aerobically degrades 1,1-dichloro-2,2-bis-(4-chlorophenyl)-ethylene (DDE) to 4-chlorobenzoate, when grown in the presence of biphenyl (BP). The intermediates of degradation were inferred to be the end products of dioxygenase activity. Sequencing of a large linear plasmid, pBPH-1, from strain DDE-1 identified a cluster of genes with high levels of sequence similarity to BP-degradation genes from Rhodococcus spp. and Pseudomonas spp. This plasmid is lost at high frequency producing the plasmid-cured strain MJ-2, which has lost the ability to degrade BP or DDE. The aim of this study was to confirm that DDE-degradation in strain DDE-1 is encoded by the bph operon located on pBPH-1. No genetic systems to study gene function in either DDE-1 or MJ-2 could be developed using an array of broad-host range vectors. However, heterologous expression of the bph genes in Rhodococcus erythropolis strain TA422 was successful, with the recombinant strain TA425, obtaining the ability to utilise BP and DDE as a sole source of carbon and energy. DDE-1 was shown to convert indole to indigo, but MJ-2 could not, indicating that the biphenyl dioxygenase located on pBPH-1 is responsible for this activity. The bph genes from strain DDE-1 also conferred the ability to produce indigo from indole on strain TA425, confirming successful expression of the functional biphenyl dioxygenase in this strain. Despite several attempts to show quantitative degradation in strain TA425 using gas chromatography, the results were inconclusive Further analysis is needed to provide unequivocal evidence of DDE-degradation by strain TA425. Attempts to express the bph genes in rhizosphere-colonising bacteria, such a Rhizobium spp. or Pseudomonas spp., were unsuccessful, as evidenced by the inability to produce indigo, hence the lack of a functional biphenyl dioxygenase. However, RT-PCR did indeed indicate that P. aeruginosa strain Fin1 produced a bphA1 transcript, indicating that an error is occurring post-transcriptionally in these strains, to prevent production of the functional enzyme.
New Zealand has recently been shown to contain hotspots of DDTr-contamination. The second aim of this study was to determine the prevalence of DDTr-degrading bacteria and to gain insight into the types of bacteria that inhabit sites contaminated with DDTr. To investigate this, culture-dependent and culture-independent techniques were employed. Enrichment for DDTr-degrading bacteria yielded species of Rhodococcus and Ralstonia using DDTr-overlayer plate assays. The polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) were used to amplify and analyse the 16S rDNA and 16S rRNA for the identification of dominant and active bacteria in soil samples. The results of this analysis identified bacteria such as Williamsia spp. and Gordonia spp. that degrade other types of pollutants. This analysis did not identify a predominance of Rhodococcus or Ralstonia spp., or other bacteria that have been shown to degrade DDTr. To identify ecologically relevant members of the bacterial communities in DDTr-contaminated soils, and potentially important metabolic pathways, identification of ring-hydroxylating dioxygenase (RHD) genes was performed. PCR and restriction fragment length polymorphism (RFLP) analysis were employed together with phylogenetic analyses. The results showed that the RHD genes identified, clustered separately to those genes previously characterised from cultivated bacteria. Among these genes, one phylogenetic group was most closely related to the dioxygenase genes from Ralstonia eutropha H850, which is potent PCB-degrading bacterium that possesses a dioxygenase with a wide substrate range for many types of heavily chlorinated, PCB congeners. The identification of a predominance of genes with similarity to phenyl-propionate dioxygenases has been not been recognised previously in soil studies.
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Sheeka, Hendrika Maria. "Design and synthesis of novel nucleotide pro-drugs as anti-HIV agents." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295004.
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Hedberg, Julia, and Maria Jernnäs. "DDT - Hero or Villain? : A Case Study on Perceptions of DDT for IRS in the Limpopo Province, South Africa." Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-106922.
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The debate regarding the advantages and disadvantages of using DDT for IRS has divided the scientific community. The health benefits of reducing malaria spreading are weighed against the potential health and environmental consequences of the chemical, and opinions also differ regarding the cost-effectiveness of the use of DDT. Global recommendations regarding use of DDT for IRS have been issued by the WHO, and the receipt of these on the local level is determined by the intended beneficiaries’ perception of legitimacy of the organisation. The WHO recommendations on DDT as well as interviews conducted with residents of a South African village and representatives for two South African NGOs have been reviewed using qualitative content analysis. This method was used to highlight different perceptions of and views on DDT use, as well as for examining the potential effect that the interviewees’ perception of international institutions’ legitimacy has on their views on DDT. This study shows that the controversy regarding DDT is not as prominent on the local level as on the global level, and that the perceptions of IRS with DDT differ between the WHO, the NGOs and the residents of the village. Further, this study shows that assessing legitimacy is dependent on a definition of “the people” in question, and that the accountability of authoritative actors on different levels needs to be evaluated further.
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Asp, Vendela. "In Vitro Studies of Adrenocorticolytic DDT Metabolites, with Special Focus on 3-methylsulfonyl-DDE." Doctoral thesis, Uppsala universitet, Ekotoxikologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122721.
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The DDT metabolite 3-methylsulfonyl-DDE (3-MeSO2-DDE) is bioactivated by cytochrome P450 11B1 (CYP11B1) in the adrenal cortex of mice and forms irreversibly bound protein adducts, reduces glucocorticoid secretion, and induces cell death selectively in cortisol-producing adrenocortical cells. 3-MeSO2-DDE has therefore been proposed as a lead compound for an improved adrenocortical carcinoma (ACC) therapy. The aims of this thesis were to (1) develop in vitro test systems based on murine and human adrenocortical cell lines and to (2) investigate the mechanisms behind 3-MeSO2-DDE toxicity in adrenocortical cells. The cytotoxic and endocrine-modulating effects of 3-MeSO2-DDE were compared to those of o,p′-DDD (mitotane), the current ACC therapy, and to those of several structurally analogous compounds in both murine and human cell lines. 3-MeSO2-DDE bioactivation and cytotoxicity proceeded in a similar manner in the murine adrenocortical Y-1 cell line as in mice in vivo. The effects were highly structure-specific. Moreover, 3-MeSO2-DDE formed irreversibly bound protein adducts and caused cell death also in the human H295R cell line, and was slightly more cytotoxic than o,p′-DDD. However, 3-MeSO2-DDE toxicity in human cells was not affected by the CYP11B1 inhibitor etomidate, suggesting that bioactivation in human cells is performed by additional/other enzyme(s) than CYP11B1. 3-MeSO2-DDE generated biphasic responses in cortisol and aldosterone secretion and in expression levels of the steroidogenic genes CYP11B1, CYP11B2, and StAR. Such hormesis-like responses were not seen for o,p′-DDD or the precursor DDT metabolite p,p′-DDE. In addition, the two o,p′-DDD enantiomers (R)-(+)-o,p′-DDD and (S)-(-)-o,p′-DDD exhibited slight differences in cytotoxic and endocrine-modulating activity in H295R cells. In conclusion, this thesis provides extended knowledge on the mechanisms of action of 3-MeSO2-DDE and points out important differences in effects between murine and human cells. Lead optimisation studies of 3-MeSO2-DDE using the herein presented in vitro test systems are ongoing.
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Rostant, Wayne Geoffrey. "Sex-specific effects of DDT resistance in flies." Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/10521.
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In D. melanogaster, resistance to DDT is conferred by the upregulation of a cytochrome P450 enzyme, CYP6G1. Resistant flies have tandemly duplicated Cyp6g1 alleles that possess the LTR (Long Terminal Repeat) of an Accord retrotransposon inserted in the cis-regulatory region, 291bp upstream of the transcription start site. This DDT resistance allele (DDT-R) has been shown to have pleiotropic fitness benefits for female flies in at least one genetic background and with evidence of sexually antagonistic selection at this locus. In this thesis, I first review the role of transposable elements in conferring insecticide resistance and the evidence to date regarding the pleiotropic effects of DDT-R in D. melanogaster. By conducting life history and behavioural tests on flies of two genetic backgrounds I examine the sex-specific effects of expressing DDT-R in the absence of DDT. Finally I develop a single locus population genetics model based on these sex-specific effects and test the model using replicate laboratory populations. The first main finding is that DDT-R incurred a male mating cost that depended on the genetic background in which DDT-R was found and that this cost coincided with strong epistasis between genetic background and DDT-R that influenced male size (Chapter 3). Following on from this result, it was confirmed that the effect of DDT-R on male size does contribute to lowered mating success but does not fully explain this fitness cost (Chapter4). Additionally, resistant males were found to have a lowered rate of courtship behaviour driven by aborted chasing of females and lower male-male aggression than susceptible males (Chapter 4). Fitness assays in wild caught strain females revealed that DDT-R confers a fecundity increase but unlike previous work, no offspring viability increases were detected (Chapter 5). Thus as with male costs, specific pleiotropic female fitness benefits to resistance depend on genetic background. Modelling of DDT-R using a simple single-locus approach (Chapter 6) provides, for the first time, a unifying explanation for past and present DDT-R frequencies in nature and in old laboratory populations. The model is consistent with an old origin for the original DDT-R mutation held at low equilibrium frequency through balancing selection of a sexually antagonistic nature. It is also consistent with continued near fixation of DDT-R long after discontinued use and matches empirical observations in laboratory populations of the Canton-S background.
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Garritson, Emily M. "DDT: Historical Framework, Current Uses, & Future Implications." Miami University Honors Theses / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1209157311.
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Cantillana, Tatiana. "Toxicologically important DDT metabolites : Synthesis, enantioselective analysis and kinetics." Doctoral thesis, Stockholms universitet, Institutionen för miljökemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-26952.
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DDT was extensively and globally used as a pesticide in agriculture and for malaria vector control from the 1940’s until the 1970’s. Due to its heavy use, DDT became ubiquitously distributed throughout the environment. DDT and several DDT metabolites are persistent organic pollutants. Two DDT metabolites, 3-MeSO2-DDE and o,p’-DDD have been proved to be tissue specific toxicants in the adrenal cortex. They are bioactivated to reactive intermediates which bind covalently to the adrenal cortex causing cell death. Due to its tissue specific toxicity o,p’-DDD has been used as a chemotherapy drug for adrenal cancer in humans. The efficacy and potency is however low and o,p’-DDD treatment is associated with serious side effects. 3-MeSO2-DDE has been suggested as a potential alternative therapeutic agent. A key aim of this thesis has been to improve the understanding of the kinetics of the two adrenocorticolytic compounds o,p’-DDD, its two enantiomers and 3-MeSO2-DDE. To meet this objective chemical synthesis and enantioselective analysis were required. Furthermore, in vitro toxicity of o,p’-DDD enantiomers and diastereomers were performed. An 11 step synthesis of 3-SH-DDE has been developed to promote both labelled and unlabelled synthesis of 3-alkylsulfonyl-DDE. Toxicokinetic studies showed that 3-MeSO2-DDE and o,p’-DDD were accumulated in tissues and retained in adipose tissue in minipigs. 3-MeSO2-DDE however had a twice as long biological t1/2 and a considerably lower Vd compared to o,p’-DDD. Suckling offspring were more exposed to 3-MeSO2-DDE than their mothers who were given 3-MeSO2-DDE orally. Interindividual differences in enantiomer kinetics in minipigs were observed suggesting polymorphism among the minipigs. Preparative isolation of the o,p’-DDD enantiomers is presented allowing determination of the absolute structures of the o,p’-DDD enantiomers by X-ray. The pure enantiomer of o,p’-DDD showed significant differences in toxicity in human adrenocortical cells.
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Ryan, Brendan J. "The microbial degradation of the DDT metabolite dichlorobenzophenone (DBP)." Thesis, University of Canterbury. Microbiology, 1995. http://hdl.handle.net/10092/8554.
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Soil samples which had been previously exposed to chlorinated aromatics were screened for ability to degrade dichlorobenzophenone (DBP). Of the samples tested soil from the Dow Elanco Agricultural Farm and soil from the AgResearch Winchmore Research Station showed apparent degradative capabilities. Degradation was not sustainable in these soil samples and a time scale study showed DBP was stable in soil over a 24 week period. Samples from Winchmore were further used to establish enrichment cultures capable of degrading DBP and its non-chlorinated analogue benzophenone (BP) through selection pressure. BP proved to be readily degraded but
DBP degradation was only achieved after fungal suppressants were used. Degradation of DBP was enhanced with the addition of yeast extract and sodium salicylate to the enrichment cultures. Degradation of DBP was confirmed by capillary gas chromatography and the detection of the metabolite p-chlorophenyl acetic acid by gas chromatography-mass spectroscopy and thin layer chromatography. The enrichment cultures established on DBP also extensively degraded BP, p-chlorobenzophenone and p-chlorobenzoic acid. When inoculated back into soil, the enrichment cultures degradative capabilities were significantly reduced due to competition from other organisms, availability of alternative carbon sources and the bioavailability of DBP due to binding to soil particles.
Two organisms capable of degrading BP as sole carbon source were isolated and identified as a Rhodococcus spp. and a Streptomyces spp. BP degradative capabilities were not maintained by these organisms and lost when subculturing on nutrient media
Three presumptive DBP degraders were isolated and presumptively identified as two separate Streptomyces spp. and a Pseudomonas vesicularis. Of the three none were able to degrade DBP as sole carbon source in liquid culture although the P. vesicularis was able to co-metabolise DBP with the addition of yeast extract and sodium salicylate.
Preliminary genetical studies of the P. vesicularis isolated were carried out.
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Sheikh, Sohail Hamid. "Investigations of molecular fluorescence based measurement of DDT residues." Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267496.
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Ahmed, Mohamed Saifelislam Abdelgadir. "Run-Up Distance From Deflagration to Detonation In Fast Flames." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34592.
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In the process of deflagration-to-detonation transition (DDT) in reactive gases, the flame typically accelerates first to the choked flame condition (known as a Chapman-Jouguet deflagration), where it propagates at the sound speed with respect to the product gases. Subsequently, the choked flame may transit to a detonation. In the present study, the transition length from choked flames to detonations was measured experimentally in laboratory-scale experiments in methane, ethane, ethylene, acetylene, and propane with oxygen as oxidizer. The choked flames were first generated following the quenching of an incident detonation after its interaction with cylindrical obstacles with two different blockage ratios, 75\% and 90\%. Comparison with a recently proposed model confirms that these are Chapman-Jouguet deflagrations. The subsequent acceleration was monitored via large-scale time-resolved shadowgraphy. The mechanism of transition was found to be through the amplification of transverse waves and hot spot ignition from local Mach reflections. The transition length was found to correlate very well with the mixture's sensitivity to temperature and pressure fluctuations. These fluctuations could be connected to a unique parameter (X), introduced by Radulescu. The parameter is the product of the non-dimensional activation energy (Ea/RT) and the ratio of chemical induction to reaction time (ti/tr). Mixtures with a higher X were found to be more prompt to hot spot ignition and amplification of the fast flame into detonations. The run-up distance for unstable mixtures was found to be much shorter than anticipated from a model neglecting the fluctuations in a 1-D framework. The run-up distance was also correlated to the detonation cell size, yielding LDDT ~ 7 - 50 cells, with the proportionality coefficient depending on X and the obstacle blockage ratio. Finally, a unique correlation for the run-up distance is proposed, yielding LDDT ~ 3000 c tr, where c is the sound speed in the shocked non-reacted gas, valid for large X.
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Van, Tonder Jacob John. "Development of an in vitro mechanistic toxicity screening model using cultured hepatocytes." Thesis, University of Pretoria, 2011. http://hdl.handle.net/2263/24162.
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In vitro testing includes both cell-based and cell-free systems that can be used to detect toxicity induced by xenobiotics. In vitro methods are especially useful in rapidly gathering intelligence regarding the toxicity of compounds for which none is available such as new chemical entities developed in the pharmaceutical industry. In addition to this, in vitro investigations are invaluable in providing information concerning mechanisms of toxicity of xenobiotics. This type of toxicity testing has gained popularity among the research and development community because of a number of advantages such as scalability to high throughput screening, cost-effectiveness and predictive power. Hepatotoxicity is one of the major causes of drug attrition and the high cost associated with drug development poses a heavy burden on the development of new chemical entities. Early detection of hepatotoxic agents by in vitro methods will improve lead optimisation and decrease the cost of drug development and reduce drug-induced liver injury. Literature highlights the need for a cellbased in vitro model that is capable of assessing multiple toxicity parameters, which assesses a wider scope of toxicity and would be able to detect subtle types of hepatotoxicity. The present study was aimed at developing an in vitro procedure capable of mechanistically profiling the effects of known hepatotoxin dichlorodiphenyl trichloroethane (DDT) and its metabolites, dichlorodiphenyl dichloroethylene (DDE) and dichlorodiphenyl dichloroethane (DDD) on an established liver-derived cell line, HepG2, by evaluating several different aspects of cellular function using a number of simultaneous in vitro assays on a single 96 well microplate. Examined parameters have been suggested by the European Medicines Agency and include: cell viability, phase I metabolism, oxidative stress, mitochondrial toxicity and mode of cell death (apoptosis vs. necrosis). To further assess whether the developed method was capable of detecting hepatoprotection, the effect of the known hepatoprotectant, N-acetylcysteine, was determined. Viability decreased in a dose-dependent manner yielding IC50 values of 54 μM, 64 μM and 44 μM for DDT, DDE and DDD, respectively. Evaluation of phase I metabolism showed that cytochrome P4501A1 activity was dose-dependently induced. Test compounds decreasedlevels of reactive oxygen species, and significantly hyperpolarised the mitochondrialmembrane potential. Assessment of the mode of cell death revealed a significant elevation of caspase-3 activity, with DDD proving to be most potent. DDT alone induced dosedependent loss of membrane integrity. These results suggest that the tested compounds produce apoptotic death likely due to mitochondrial toxicity with subsequent caspase-3 activation and apoptotic cell death. The developed in vitro assay method reduces the time it would take to assess the tested parameters separately, produces results from multiple endpoints that broadens the scope of toxicity compared to single-endpoint methods. In addition to this the method provides results that are truly comparable as all of the assays utilise the same batch of cells and are conducted on the same plate under the exact same conditions, which eliminates a considerable amount of variability that would be unavoidable otherwise. The present study laid a solid foundation for further development of this method by highlighting the unforeseen shortcomings that can be adjusted to improve scalability and predictive power.Thesis (PhD)--University of Pretoria, 2011.
Pharmacology
unrestricted
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Yayo, AdulSalami. "Characterisation of glutathione S-transferase-based DDT resistance in Anopheles arabiensis." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439501.
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Kantachote, Duangporn. "The use of microbial inoculants to enhance DDT degradation in contaminated soil." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phk165.pdf.
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Tran, Van Nam. "Adsorption statique de PCB et de DDT sur charbons actifs en milieux aqueux." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10301.
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L’adsorption solide-liquide des PCB et des DDT constitue un moyen efficace pour leur récupération des eaux polluées à condition d’avoir une meilleure connaissance du mécanisme impliqué. Les cinétiques d’adsorption statique ont été principalement réalisées à 25 °C avec le2-PCB, un mélange de tétra-, penta- et hexa-CB et le 4,4’-DDT sur 3 charbons actifs (CA) en poudre différents par le précurseur (houille, bois) et le mode d’activation (H2O, H3PO4) dans l’eau, en présence ou non d’éthanol. Les résultats marquants ont été les suivants : L’adsorption du polluant sur le CA est d’autant plus favorisée que sa solubilité dans la phase liquide est plus faible. Ainsi, l’adsorption du polluant hydrophobe est très augmentée dans l’eau pure. L’adsorption des polluants favorisée par la microporosité développée est essentiellement un phénomène de surface où interviennent les forces de Van der Waals. Une bonne adéquation entre la taille des molécules et la largeur moyenne des pores en forme de fentes montre un confinement maximum des molécules dans la microporosité. L’interaction π−π entre adsorbat et adsorbant, favorisée par le nombre de Cl n’est pas à exclure. Enfin, nous avons montré par la cinétique dans les conditions initiales que l’adsorption y est limitée par le transfert de masse externe. Les modélisations par diffusion superficielle homogène (HSDM), conduisant aux coefficients de diffusion superficielle interne, ont montré que la cinétiqued’adsorption est presque complètement gouvernée par la diffusion intraparticulaireThe solid-liquid adsorption of PCBs and DDT is an effective process for the recuperation of wastewaters but a better understanding of the involved mechanism is required. In this study, the static adsorption kinetics were mainly carried out at 25 ° C for 2-PCB, a mixture of tetra-, penta-and hexa-CB, and 4,4 '-DDT onto three different powdered activated carbons (AC) of the precursor (coal, wood) and the activation mode (H2O, H3PO4) in water, with or without ethanol. The prominent results were as follows: The adsorption of the pollutant on the AC is favored if its solubility in the liquid phase is lower. As a result, the adsorption of the hydrophobic pollutant is significantly increased in pure water. Moreover, the adsorption of pollutants favored by the developed microporosity is a surface phenomenon which involved the Van der Waals forces. A good fit between the size of molecules and the average width of the slit-shape pores gave a maximum confinement of molecules in the micropores. The π−π interaction between adsorbate and adsorbent, favored by the number of Cl, is not excluded. Finally, by studying the kinetics of the initial conditions, we found that the adsorption is limited by the external mass transfer. The internal surface diffusion coefficients estimated from applying the homogeneous surface diffusion models (HSDM) showed that the adsorption kinetics are almost completely governed by the intra-particle diffusion
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Castañeda, Chávez Maria del Refugio. "Evaluation des niveaux de contamination de l’huître Crassostrea virginica par le DDT et ses métabolites." Brest, 2006. http://www.theses.fr/2006BRES2020.
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Dans l’état de Veracruz, l’activité ostréicole se réalise sur une surface lagunaire de 107000 dont 1425 sont des bancs ostréicoles et cette ressource est exploitée par 14 organisations connues comme coopératives ostréicoles. Ces systèmes présentent actuellement des problèmes de surexploitation, de gestion aquacole inadéquate, d’écologie et de contamination chimique et micro-biologique. La présence de cette dernière a un effet direct sur l’huître Crassostrea virginica qui est la base de la production nationale, représentant 26000 tonnes/Ha/an. A partir de 1993, le secrétariat de la santé (SSA) a recommandé l’application de la NOM-031-SSA1993, qui préconise l’application de méthodes d’épuration ou de purge avant la consommation du mollusque bivalve. Néanmoins, cette norme ne considère point l’effet de l’application de ces méthodes vu la présence de polluants chimiques tels que les pesticides dans les systèmes lagunairesIn Veracruz, the oyster activity is made in a surface to lagoons of 107 000 you have of which 1425 you have are of oysters banks and the resource is operated by means of 14 organizations known like oysters cooperatives. In these systems they at the moment appear a problematic one of on operation of the resource, inadequate acuicola handling, ecological problems and chemical and microbiological contamination; mainly the presence of this completes has a direct influence in the American oyster C. Virginica (Gmelin, 1742), that is the base of the production at national level contributing 26. 000 ton/ha/años. As of the 1993, the Secretary (SSA), recommends the application of the NOM-031-SSA1993, in which me application of methods of bled purification is recommended before the consumption of bivalvos moluscos or, nevertheless this NOM, does not consider the possible effect of the use of these methods in the presence of chemical polluting agents as lagoons is the case of the plaguicidas in the systems and in the organism. Objectif of this work was to evaluate me levels of contamination by DDT and their metabolites in virginica C. In Seeing. Mexico; the study was divided in three stages: In the first stage its relation with the parameters of average like temperature and the salinity was evaluated biological cf the oyster and during an annual cycle in two systems lagoon; Tamiahua and Vega de Alatorre; I am observed in Fertile Vega de Alatorre that the behavior of the temperature is similar to me one of Tamiahua
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Nirwal, Amardeep Singh. "Environmental behaviour and fate of dichlorodiphenyltrichloroethane, DDT, residues in a terrestrial arctic ecosystem." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63347.pdf.
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Mbongwe, Bontle. "Fate and persistence of DDT and its metabolites in the Okavango Delta, Botswana." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ67838.pdf.
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Kere, Nathan Kumamusa. "Permethrin impregnated bednets and DDT residual spraying : multicentre comparative trial in Solomon Islands." Thesis, London School of Hygiene and Tropical Medicine (University of London), 1992. http://researchonline.lshtm.ac.uk/682344/.
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A malaria intervention comparative trial was carried out in Solomon Islands between 1987 and 1992, involving 7 pairs 14 communities, with 29,182 people. Seven communities were given bed nets impregnated with permethrin annually at 0.5g/m2, and the others sprayed biannually with DDT at dosage 2g/m2. Each pair was evaluated for about two years, by measuring entomological indices, prevalence of infection, incidence of infection, and levels of community compliance. An intensive differential cost analysis of both interventions was done in one pair of the communities and an analysis on cost and benefit of PCD mechanism was done in three pairs. Anopheles farauti, the main vector, (A. punctulatus, an inland vector became very rare with interventions), maintained the early evening biting peak and high outdoor biting. The highest transmission potential was indoor with high parity (54.1%) and sporozoite rate (1.42%). It avoided contact on DDT sprayed surface and was not killed even though it was still sensitive with a 75.1% mortality. There were neither changes in biting density, nor parous rates with DDT spraying. Permethrin impregnated bed nets reduced biting density by an estimated 53.69%. The parous rate indoor was reduced by 11.64% when compared with that in the comparison area, and those caught in the bed nets area did not have any sporozoites. Prevalence of infection, by quarterly prevalence surveys revealed a 21.2% difference between the intervention areas after two years. The most significant decline was in the under 10 year old group (p<0.01) in permethrin treated bed nets, including in infants (p<0.05). The decline was especially marked with Plasmodium falciparum. There were increases in the DDT area, including P. falciparum in the younger age groups. DDT spraying did not have any effect on the incidence of infection. Permethrin impregnated bed nets reduced malaria incidence, by an estimated 49%. This reduction was particularly significant however on children under ten years old (p<0.0001) and marked with P. falciparum. Compliance with DDT declined by 30% but with bednets it remained high above 85%. These results confirmed that permethrin impregnated bednets are more effective than DDT residual spraying in controlling malaria in Solomon Islands. The operational costs for DDT spraying was $8.53 and impregnated bed nets $3.85 per capita per year. The mean cost of processing and examining a PCD slide is $0.40. These cost indices took account of all materials, personnel and administration involved. It took a mean of 6.1 days from the time the smear was taken to the time examined (SE = 0.21,95%CI 5.71 to 6.53 days). It would take twice this time for a result to be received by the health workers managing patients. Only 20% of blood slides could contribute to patient management. Based on these findings, all that is necessary is to make blood smears of patients less than 10 years of age for epidemiological evaluation of vector control interventions in malaria programme. This will save scarce resources at primary health care level. Making blood slides of everyone would not further add significant information and benefit, at an extra cost. The only exceptions are, those critically ill with malaria, complicated malaria and a patient suspected to have drug resistant malaria. Permethrin impregnated bednets are a cost effective way to control malaria in primary health care and the most cost benefit way to evaluate vector control intervention is careful monitoring of PCD results, especially with P. falciparum malaria of children under 10 years old.
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Sullivan, Joseph P. "Blood characteristics as predictors of reproductive success in quail species exposed to DDT." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/37409.
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Lindström, Veronica. "Adrenocorticolysis induced by 3-MeSO2-DDE : mechanisms of action, kinetics and species differences /." Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8180.
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藤村, 佳樹, and 新太 片山. "土壌中の細菌に対する DDT の分配." 日本農薬学会, 1993. http://hdl.handle.net/2237/10912.
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Fisher, Dean R. "Fate of DDT, 2,4-D and 2,4,5-T during bioremediation of pesticide-contaminated soils." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0026/MQ51065.pdf.
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Chu, Wing Kei. "Accumulation and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L." HKBU Institutional Repository, 2004. http://repository.hkbu.edu.hk/etd_ra/530.
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Elia, Andrew James Carleton University Dissertation Biology. "Effects of DDT on central nervous system activity in the cockroach, Periplaneta americana (L.)." Ottawa, 1989.
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Wang, Wentian. "Models of CJ Deflagrations and Their Transition to Detonations from the Interaction of a Detonation Wave with a Perforated Plate." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39411.
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The last stage of a deflagration-to-detonation transition (DDT) process involves the propagation and acceleration of a fast flame. This process is currently poorly understood. The difficulties lie in its complex structure, which is turbulent and involves multi-dimensional gasdynamic phenomena. Previous experimental studies have established these fast flames from the interaction of a detonation wave with a row of obstacles or porous plate. Two main questions remain unsolved: 1) What is the propagation speed of the fast flame obtained in these configurations and 2), Which factors dominate the occurrence of the DDT phenomenon? To answer these questions, two models have been constructed in the present work.
Firstly, a quasi-1D gasdynamic model is proposed for estimating the transmitted reaction front speed and the strength of the transmitted shock. By alternately assuming a Chapman-Jouguet (CJ) deflagration or an inert shock, the model estimated the transmitted shock speeds. The comparison with extensive experimental data for a range of hydrocarbon fast flames revealed that the burning velocity required for transition to detonation was the CJ value.
Secondly, a numerical shock-induced ignition model, which can impose mechanical fluctuations from a driven piston, was established in order to investigate the ignition and acceleration process, thereby clarifying the other question of interest. The results from the simulations indicated that the mechanical fluctuations can play an important role in triggering DDT by means of promoting the local ignition and amplification of the reaction front stemming from such ignition. It was also found that the maximum amplification effects occur with a fluctuation period between the non-fluctuated ignition delay and the time scale of chemical energy deposition. The inert simulation results show that two types of gasdynamic effects from the fluctuations were vital to the hot-spot formation. These hot spots make significant contribution to the detonation initiation.
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Taurozaitė, Kristina. "Buvusių pesticidų sandėlių teritorijų užterštumo pesticidų likučiais vertinimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2008~D_20101125_185309-65271.
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Kristina Taurozaitė Buvusių pesticidų sandėlių teritorijų užterštumo pesticidų likučiais vertinimas Santrauka Didžiausia tarša pesticidais stebima dirvožemyje ir požeminiuose gruntiniuose vandenyse, pesticidų kapinynų aplinkvietėse ir buvusių pesticidų sandėlių gaisravietėse, o pagrindiniai taršos pesticidais židiniai yra pesticidų sandelio gaisrai ir pesticidų kapinynai. Pesticidų sukeltas neigiamas poveikis aplinkai yra negrįžtamas, o tai pasireiškia įvairiais išsigimimais, nukrypimais ir ligomis žmonėms, gyvūnams bei augalijai. Iš atliktų dirvožemio bei grunto tyrimų Marijampolio ir Tryškių pesticidų sandeliuose 0,0 – 0,3 m gylyje nustatyta, kad kai kurių pesticidų koncentracijos viršija HN 60:2004 nustatytas DLK vertes nuo 1 iki 1460 kartų Marijampolio pesticidų sandelyje, o Tryškių pesticidų sandelyje nuo 1,5 iki 3600 kartų. Tuo tarpu tų pačių pesticidų koncentracijos grunto bandiniuose iš 0,9 – 1,0 m gylio sumažėja ir DLK viršijamos tik nuo 1 iki 38 kartų Marijampolio pesticidų sandelyje ir iki 144 kartų Tryškių pesticidų sandelyje. Iš atlikus gruntinio vandens tyrimų buvo nustatyta, kad Tryškių pesticidų sandėlio teritorijoje požeminis (gruntinis) vanduo yra smarkiai užterštas pesticidais. Jo tarša atskirais pesticidais skirtingais normatyviniais aktais nustatytas DLK viršija iki 96 kartų Tryškių ir iki tūkstančių kartų Marijampolio pesticidų sandelių teritorijose. Todėl galima teigti, kad Marijampolio pesticidų sandelio teritorijoje gruntinis vanduo užterštas labiau... [toliau žr. visą tekstą]Kristina Taurozaitė The estimation of existed pesticides dumps contamination with pesticides residues Summary The biggest pollution of the pesticides is fixed in soil and ground water areas of the pesticides dumps and sites after a fire of the pesticides warehouses. The main sources of the pollution of the pesticides are fire of the warehouses of the pesticides and pesticides dumps. The negative impact on environment of pesticides is irreversible, causing various degenerations, aberrations and diseases to animals and plants. It was estimated that in Marijampolio and Tryškių pesticides dumps, concentration of some pesticides exceeds HN 60:2004 stated MCL (maximum concentration levels) values from 1 to 1460 times in Marijampolio pesticide dump while in Tryškių pesticides dump from 1,5 to 3600 times. Whereas the same concentration in ground samples in 0,9 -1.0 depth declines and MCL exceed just from 1 to 38 times in Marijampolio pesticides dumps, and to 144 times in Tryškių pesticides dumps. In Tryškių and Marijampolio pesticides dumps soil and ground analyses were made. It was estimted that ground water in Tryškių pesticide dump area is polluted deeply by pesticides. Its pollution of separate pesticides by different normative act stated MCL exeeds to 96 times in Tryškių and to 1000 times in Marijampolio pesticides dumps areas. That is why ground water of Marijampolio pesticides dumps areas is poluted more than in Tryškių pesticides dumps area. Analytically analyzed pesticides... [to full text]
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Romano, Massimiliano. "Experimental investigation on the sensitization of hydrocarbon-oxygen mixtures to DDT via cool flame oxidation." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33992.
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The effect of cool flame partial oxidation on the detonation sensitivity of a hydrocarbon fuel was investigated experimentally. The detonation sensitivity was quantified by measuring the run-up distance required for a deflagration to transit to a detonation wave (DDT) in a rough tube. Fuel rich pentane-oxygen mixtures at subatmospheric initial pressures were studied. Subsequent to the injection of the mixture into the heated detonation tube, the mixture underwent cool flame oxidation after a well controlled delay time, as it was determined by the temperature of the tube. Typical delays ranged from 0.7 to 2 seconds (depending on temperature) and were reproducible to within one hundred milliseconds. This permitted to spark-ignite the mixture in the detonation tube at various stages of its cool flame process. The results show that increasing mixture temperature from room temperature to values below the cool flame region (below 250°C) resulted in an increase in run-up distance. However, as the mixture begins to undergo cool flame oxidization a significant reduction in the run-up distance was obtained (as large as 50%). The sensitization effect was found to occur only at the initial stage of the cool flame oxidation reaction. If the mixture is ignited at times long after the onset of cool flame, the mixture was found to be desensitized and the run-up distance increased. The sensitizing effect of the cool flame partial oxidation may be attributed to the presence of peroxides and free radicals associated with the initial cool flame process. However these radical species are consumed as the cool flame reaction proceeds and the mixture becomes insensitive again.
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Kucher, Sebastian Verfasser], Jan [Akademischer Betreuer] [Schwarzbauer, and Sven [Akademischer Betreuer] Sindern. "Environmental fate of DDT-related compounds in aquatic systems / Sebastian Kucher ; Jan Schwarzbauer, Sven Sindern." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1180392124/34.
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Antunes, Paulo José Freire. "Accumulation of PCB congeners and DDT compounds in fish: influence of size and reproductive cycle." Doctoral thesis, Instituto de Ciências Biomédicas Abel Salazar, 2008. http://hdl.handle.net/10216/9316.
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Kucher, Sebastian [Verfasser], Jan [Akademischer Betreuer] Schwarzbauer, and Sven [Akademischer Betreuer] Sindern. "Environmental fate of DDT-related compounds in aquatic systems / Sebastian Kucher ; Jan Schwarzbauer, Sven Sindern." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1180392124/34.
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Somerville, Michael Francis. "DDt concentrations in soils in sprayed and unsprayed areas of two towns in southern Belize." [Pensacola, Fla.] : University of West Florida, 2009. http://purl.fcla.edu/fcla/etd/WFE0000194.
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Thesis (M.S.)--University of West Florida, 2009.Submitted to the Dept. of Environmental Studies. Title from title page of source document. Document formatted into pages; contains 119 pages. Includes bibliographical references.
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Antunes, Paulo José Freire. "Accumulation of PCB congeners and DDT compounds in fish: influence of size and reproductive cycle." Tese, Instituto de Ciências Biomédicas Abel Salazar, 2008. http://hdl.handle.net/10216/9316.
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Siu, Ka-yan Sky. "DDT as a malarial vector control method and its potential risks to human reproductive health and neonatal development." View the Table of Contents & Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/record/B3847864X.
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Rondon, Mariza Grimmer de Almeida. "Estudo das alterações hematológicas e bioquímicas em população exposta a resíduos de pesticidas organoclorados: inquérito na cidade dos meninos, município de Duque de Caxias, 2004." reponame:Repositório Institucional da FIOCRUZ, 2007. https://www.arca.fiocruz.br/handle/icict/5065.
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Previous issue date: 2007Este é um estudo descritivo exploratório sobre as alterações hematológicas ebioquímicas causadas pela exposição crônica a resíduos de pesticidas organoclorados da população de Cidade dos Meninos, Município de Duque de Caxias, Estado do Rio de Janeiro.Foi observado aumento da prevalência de anemia, em especial entre os homens,com aumento proporcional ao aumento dos níveis de contaminação, e ao maior número de contaminantes, leucocitose e neutropenia. Em relação às provas de função hepática, houve aumento significativo da y-GT, em ambos os sexos, com prevalências maioresnas mulheres. As prevalências são também maiores nos indivíduos que declararam não fazer uso de bebidas alcoólicas, independentemente do sexo.
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Sibali, LL, JO Okonkwo, and C. Zvinowanda. "Determination of DDT and Metabolites in Surface Water and Sediment Using LLE, SPE, ACE and SE." Springer Science, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001502.
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Abstract
Surface water and sediment samples collected
from Jukskei River in South Africa, were subjected to
different extraction techniques, liquid–liquid (LLE), solidphase
extraction (SPE), activated carbon extraction (ACE)
and soxhlet extraction (SE) for sediment. The samples were
extracted with dichloromethane, cleaned in a silica gel
column and the extracts quantified using a Varian 3800
GC-ECD. The percentage recovery test for 2,40DDT, DDE
and DDD and 4,40DDT, DDE and DDD in water ranged
from 80%–96% and 76%–95% (LLE); 56%–76% and
56%–70% (SPE) and 75%–84% (ACE), respectively; while
that recoveries for sediment samples varied from 65%–
95% for 2,40DDT, DDE and DDD and 80%–91% for
4,40DDT, DDE and DDD. The high recoveries exhibited by
ACE compared very well with LLE and SE. This was not
the case with SPE which exhibited the lowest value of
recoveries for both 2,4 and 4,40DDD, DDE and DDT
standard samples. The mean concentrations of DDT and
metabolites ranged from nd-1.10 lg/L, nd-0.80 lg/L, nd-
1.21 lg/L and 1.92 lg/L for LLE, SPE, ACE and SE,
respectively. The total DDT (2,40 and 4,40-DDT) in water
and sediment samples ranged from 1.20–3.25 lg/L and
1.82–5.24 lg/L, respectively. The low concentrations of
the DDT metabolites obtained in the present study may
suggest a recent contamination of the river by DDT.
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Mello, Leonardo Henriques. "Histórico deposicional de Poluentes Orgânicos Persistentes em testemunhos sedimentares do ecossistema estuarino da Ilha do Marajó (Pará - Brasil)." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/21/21137/tde-22022017-181101/.
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A distribuição espacial e o histórico deposicional de poluentes orgânicos persistentes (POPs) em sedimentos foram avaliados no ecossistema marino-estuarino da Ilha do Marajó, Pará. Os pesticidas predominantes nos sedimentos da camada superficial foram os HCHs (<0,04 e 0,90 ng g-1) e DDTs (<0,02 - 2,72 ng g-1), em peso seco. PCBs e PBDEs não foram detectados. HCHs predominaram no Estuário do Rio Paracauari indicando uso recente provavelmente relacionado à atividade madeireira. DDTs foram detectados na Praia do Pesqueiro e nos testemunhos sedimentares (<0,02 - 12,31 ng g-1 peso seco) do Mercado, Fazenda e Paracauari. Os valores máximos de DDT ocorreram entre 1982 e 2008 e são associados com campanhas de saúde púbica. Há uma redução gradativa até o presente que coincide com a substituição do DDT por piretróides. A razão ΣDDDs / ΣDDEs, predominantemente < 1, indicou a ocorrência de processos decomposicionais aeróbicos. No geral, as condições ambientais não favorecem o acúmulo de pesticidas nos sedimentos, sendo que os valores estão abaixo do limite provável para causar efeitos adversos exceto para HCHs no Estuário do Rio Paracauari. O presente trabalho estabeleceu a distribuição de POPs na Ilha do Marajó e poderá contribuir para o processo de gestão costeira e ambiental da região.The spatial distribution and depositional history of persistent organic pollutants (POPs) in sediments were evaluated in marino-estuarine ecosystem of Marajó Island, Pará. The predominant pesticides in sediments of the surface layer were HCHs (<0.04 and 0, 90 ng g-1) and DDTS (<0.02 to 2.72 ng g-1) by dry weight. PCBs and PBDEs weren\'t detected. HCHs predominated in Paracauari Estuary indicating recent use probably related to logging. DDTs were detected in Praia do Pesqueiro and sediment cores (<0.02 to 12.31 ng g-1 dry weight) Mercado, Fazenda and Paracauari. Maximum levels of DDT residues occurred between 1982 and 2008 and are associated with pubic health campaigns. There is a gradual reduction up to the present which coincides with the substitution of the DDTs by pyrethroids. The ratio ΣDDDs / ΣDDEs predominantly < 1 indicated the occurrence of decomposicional processes under aerobic conditions. Overall, the environmental conditions do not favor the accumulation of pesticides in sediments, and the values are below the threshold likely to cause adverse effects except for HCHs in Paracauari Estuary. This work established the distribution of POPs in Marajó Island and could contribute to the process of coastal and environmental management in the region.
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Morodi, Thabiso John. "To spray or not to spray with DDT to control malaria : a case study in environmental ethics." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53698.
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Thesis (MPhil)--Stellenbosch University, 2003.Full text to be digitised and attached to bibliographic record.
ENGLISH ABSTRACT: This assignment is devoted to an in depth analysis of the pro- and the contra-positions in the long-standing and costly debate about the question whether to spray with DDT or not in the fight against malaria. I argue that the dilemma whether or not to spray with DDT is born out of a political agenda, hype, exaggeration and misinformation of the first order. Radical environmentalists appear to insist that DDT is a principal contributor of environmental degradation, and the major cause of death amongst wildlife and humans. Worse still, many Western people seem to be under the impression that mosquitoes cannot cause so much human misery as purported, and that malaria is caused by some kind of plant form of life, or even a virus. The proponents of DDT, on the other hand, appear to be convinced that DDT is a saviour of humankind, and argue that the horrors associated with DDT are exaggerated and baseless, as they are not backed by scientific inquiry. Proponents of DDT also believe that anything that is overused may kill, even ordinary table salt. Inthis assignment, both of these positions are scrutinized. On the basis of an historical overview in Chapter I of the history of the use of DDT, and the emergence of the debate about DDT in the wake of Rachel Carson's Silent Spring (1962), Chapter 2 is devoted to an evaluation of seven basic arguments against the use of DDT, while in Chapter 3 six arguments for the use of DDT are weighed. In Chapter 4 a resolution of the dilemma is proposed in which a case is made for a limited use of DDT only for indoor spraying of huts and houses against malaria mosquitoes until such time as a less dangerous alternative for DDT is found that can be used as effectively in the fight against malaria. As such, this case is informed by the strong moral conviction that we cannot allow poor people of colour to die because of a general ban on the use of DDT. Further research on this ethical debate is encouraged.
AFRIKAANSE OPSOMMING: Hierdie werkstuk is toegespits op 'n in-diepte analise van die pro- en kontra-posisies in die voortslepende, asook duur debat oor die gebruik van DDT al dan nie in die bekamping van Malaria. Ek argumenteer dat die dilemma rondom die vraag of DDT gebruik moet word of nie, aangewakker word deur politieke agendas, sensasie, oordrywing en foutiewe informasie van die eerste orde. Radikale omgewingsgesindes dring oënskynlik daarop aan dat die gebruik van DDT 'n hoof-oorsaak is van die agteruitgang van die omgewing, asook 'n primêre oorsaak van dood onder wild en mense. Erger nog, dit wil voorkom of heelwat Westerse mense onder die indruk is dat muskiete nie werklik soveel menslike lyding kan veroorsaak as wat voorgegee word nie, en dat malaria eerder veroorsaak word deur 'n sekere soort plantvorm van lewe, of selfs deur 'n virus. Die voorstaanders van DDT, aan die ander kant, is klaarblyklik oortuig dat DDT 'n redder van die mensdom is, en argumenteer dat die gruwels wat geassosieer word met DDT 'n grondelose oordrywing is, aangesien dit nie deur wetenskaplike ondersoek gesteun word nie. Voorstaanders van DDT glo verder dat enige stof wat in oormaat gebruik word, die dood kan veroorsaak, selfs gewone tafelsout. In hierdie werkstuk word albei hierdie posisies krities bestudeer en bespreek. Op grond van 'n historiese oorsig in Hoofstuk 1 oor die gebruik van DDT, en die ontstaan van die debat oor DDT na aanleiding van Rachel Carson se Silent Spring (1962), word Hoofstuk: 2 gewy aan 'n evaluasie van sewe basiese argumente teen die gebruik van DDT, terwyl in Hoofstuk 3 ses argumente vir die gebruik van DDT oorweeg word. In Hoofstuk 4 word 'n voorstel gemaak vir die resolusie van die dilemma deur 'n saak uit te maak vir die beperkte gebruik van DDT, nl. slegs vir binneshuise gebruik in hutte en huise teen malaria-muskiete tot tyd en wyl 'n minder gevaarlike alternatief vir DDT gevind word wat net so effektief sal wees in die stryd teen malaria. As sulks word hierdie studie gerugsteun deur die sterk morele oortuiging dat ons nie kan toelaat dat mense van kleur sterf as gevolg van 'n algemene verbod op die gebruik van DDT nie. Verdere navorsing oor hierdie etiese debat word aangemoedig.
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BRUN, ALEXANDRA. "Etude de l'expression de cytochromes p450, analyse de la resistance au ddt d'une souche de drosophila melanogaster." Nice, 1996. http://www.theses.fr/1996NICE4985.
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Les cytochromes p-450 sont des enzymes qui sont impliquees dans le metabolisme endogene et exogene, notamment dans la detoxication des xenobiotiques. La premiere partie de la these porte sur l'etude de l'expression et de l'inductibilite de deux cytochromes p-450 chez drosophila melanogaster. La souche resistante raleigh ddt#r exprime constitutivement le gene cyp6a2 a un niveau eleve alors qu'il est inductible dans la souche sensible canton s. L'analyse de l'inductibilite, realisee par la mesure d'activites enzymatiques et par le suivi de l'expression en northern et western blot apres traitement des drosophiles par des inducteurs dont l'effet est connu chez les vertebres, a permis de montrer que le mecanisme de regulation des genes codant des cytochromes p-450 chez les insectes est different de celui des vertebres. Deux voir trois voies differentes d'induction de l'expression du gene cyp6a2 ont ete identifiees et mettent en evidence la complexite de la regulation des cytochromes p-450 chez les insectes. L'hybridation in situ d'arnm et l'immunohistologie ont localise l'expression de cyp6a2 dans les corps gras pericuticulaires, le tube digestif et les tubes de malpighi aussi bien dans la souche sensible induite par le phenobarbital, le prochloraze, l'aminopyrine ou la rifampicine que dans la souche resistante raleighddt#r. Dans cette derniere souche, la regulation spatiale est conservee alors que la regulation quantitative est alteree. La deuxieme partie de la these porte sur l'analyse du mecanisme de resistance au ddt de la souche raleigh ddt#r. La resistance de cette souche est multifactorielle avec au moins deux facteurs dont l'un a ete localise en position 54,4 +/- 0,9 cm du centromere sur le chromosome ii, position proche du locus qui porte cyp6a2, et le facteur responsable de la surexpression de genes codant des cytochromes p-450. Le sequencage de l'allele de cyp6a2 de raleigh ddt#r a permis de mettre en evidence deux substitutions qui se situeraient a l'entree du canal hydrophobe du cytochrome p-450 11a1 et qui pourraient donc jouer un role dans l'accessibilite du substrat a l'helice fixant l'heme
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FRANCIOSA, HELENE. "Les glutathion s-transferases : fonctions et roles dans la resistance au ddt. etude moleculaire chez musca domestica." Nice, 1994. http://www.theses.fr/1994NICE4740.
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C'est pour mieux comprendre les roles physiologiques des gst (deux familles chez la mouche domestique, gst1 et gst2) et l'implication de ces gst dans la resistance au ddt que cette etude a ete entreprise. L'adnc codant pour la gst2 de la mouche domestique a ete clone par transcription-reverse et reaction de polymerisation en chaine (rt-pcr). La sequence codante a ete soumise a la banque de donnee genbank/embl (code d'acces: u02616). Les gst ont ete immunolocalisees: la gst1 est situee dans les hemocytes, alors que la gst2 est presente dans les muscles du vol et dans les aires corticales du cerveau et du ganglion thoracique. Deux arnm de longueurs differentes codent pour la gst2 et semblent exprimes differenciellement en fonction des localisations de l'enzyme. Les gst auraient des fonctions physiologiques differents: la gst1 metaboliserait les xenobiotiques transportes par l'hemolymphe, alors que la gst2 protegerait les tissus a fort metabolisme aerobie de l'action des peroxydes. La localisation des gst montre qu'elles sont interposees entre les points d'entrees et les cibles des insecticides pour lesquels elles peuvent conferer une resistance. Les gst d'une souche de mouche domestique resistante au ddt ont ete etudiees pour examiner l'intervention de ces enzymes dans la dehydrochlorination du ddt en dde. En effet, ces mouches metabolisent de facon accrue le ddt en un produit non toxique, le dde. Cette metabolisation in vitro necessite un cofacteur: le glutathion. Ni la sequence, ni l'expression de la gst1 ne sont modifiees, alors que l'expression et la sequence (val 220-ala) de la gst2 le sont. L'implication de ces modifications dans la resistance sera a determiner
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Frische, Kerstin [Verfasser]. "Investigations on the environmental fate and contamination potential of DDT-residues in river sediment and its implication for DDA pollution of corresponding surface waters / Kerstin Frische." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018206469/34.
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Harries, Julie Elizabeth. "A study of the extent of estrogenic contamination of English inland waters." Thesis, Brunel University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336703.
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Ladonni, H. "Genetics and biochemistry of insecticide resistance in Anopheles stephensi." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384428.
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Shirley, Matt, and n/a. "Characterisation of an 84 kb linear plasmid that encodes DDE cometabolism in Terrabacter sp. strain DDE-1." University of Otago. Department of Microbiology & Immunology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20060804.094902.
Full textAbstract:
DDT, an extremely widely used organochlorine pesticide, was banned in most developed countries more than 30 years ago. However, DDT residues, including 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), still persist in the environment and have been identified as priority pollutants due to their toxicity and their ability to bioaccumulate and biomagnify in the food chain. In particular, DDE was long believed to be "enon-biodegradable"e, however some microorganisms have now been isolated that are able to metabolise DDE in pure culture. Terrabacter sp. strain DDE-1 was enriched from a DDT-contaminated agricultural soil from the Canterbury plains and is able to metabolise DDE to 4-chlorobenzoic acid when induced with biphenyl. The primary objective of this study was to identify the gene(s) responsible for Terrabacter sp. strain DDE-1�s ability to metabolise DDE and, in particular, to investigate the hypothesis that DDE-1 degrades DDE cometabolically via a biphenyl degradation pathway. Catabolism of biphenyl by strain DDE-1 was demonstrated, and a biphenyl degradation (bph) gene cluster containing bphDA1A2A3A4BCST genes was identified. The bphDA1A2A3A4BC genes are predicted to encode a biphenyl degradation upper pathway for the degradation of biphenyl to benzoate and cis-2-hydroxypenta-2,4-dienoate and the bphST genes are predicted to encode a two-component signal transduction system involved in regulation of biphenyl catabolism. The bph gene cluster was found to be located on a linear plasmid, designated pBPH1. A plasmid-cured strain (MJ-2) was unable to catabolise both biphenyl and DDE, supporting the hypothesis that strain DDE-1 degrades DDE cometabolically via the biphenyl degradation pathway. Furthermore, preliminary evidence from DDE overlayer agar plate assays suggested that Pseudomonas aeruginosa carrying the strain DDE-1 bphA1A2A3A4BC genes is able to catabolise DDE when grown in the presence of biphenyl.
A second objective of this study was to characterise pBPH1. The complete 84,054-bp sequence of the plasmid was determined. Annotation of the DNA sequence data revealed seventy-six ORFs predicted to encode proteins, four pseudogenes, and ten gene fragments. Putative functions were assigned to forty-two of the ORF and pseudogenes. Besides biphenyl catabolism, the major functional classes of the predicted proteins were transposition, regulation, heavy metal transport/resistance, and plasmid maintenance and replication. It was shown that pBPH1 has the terminal structural features of an actinomycete invertron, including terminal proteins and terminal inverted repeats (TIRs). This is the first report detailing the nucleotide sequence and characterisation of a (linear) plasmid from the genus Terrabacter.
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Hellebrandt, Aniko. "The potential of biodegradation on 1, 1, 1-trichloro-2, 2-bis (p-chlorophenyl) ethane, based upon co-metabolism of indigenous bacteria." Thesis, Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-10339.
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The purpose of this project is to evaluate the potential of a bioreactor system to degrade DDT based upon co-metabolism of indigenous bacteria. The study was performed with soil samples spiked with four different concentrations of DDT. The prepared sludge was circulated at a steady rate of revolution per minute in bioreactors with added M8 solution, cabbage leaf extract and molasses. The experiment was carried out for 7 days and chemical analysis and toxicity testing was accomplished at the beginning and the end of the experiment. The chemical analysis was essential to support the conclusions of the ecotoxicology tests. Ecotoxicology test was performed for the assessment of the toxicity (in terms of bioavailable measures) of the sludge samples, and was carried out with the Ostracodtoxkit sediment toxicity test, with the freshwater benthic crustacean test species Heterocypris incongruens. As part of the project the potential of the bioremediation method phytoremediation have been studied. Brassica Juncea seeds have been cultivated in the soil spiked with four different concentrations of DDT for one month, under stable circumstances. Growth of the plants was measured at the end of the experiment, and a chemical analysis was carried out. A thorough literature review was carried out for both the bioreactor and the phytoremediation experiments in order to obtain information about methods and theoretical background. The ecotoxicology tests and the chemical analysis showed increased p,p’- DDT concentrations in the bioreactors I. and II. at the end of the 7 day experiment, the reasons of which are not known, and require further studies.-
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Maguire, Steve. "Sustainable development, strategy & substitution, lessons from a study of the process of eliminating DDT from the economy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0010/NQ52175.pdf.
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Siu, Ka-yan Sky, and 蕭加欣. "DDT as a malarial vector control method and its potential risks to human reproductive health and neonatal development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3972458X.
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Gupta, Yashi. "Understanding the Role of Macrophage Migration Inhibitory Factor (MIF) and its Homologue D-Dopachrome Tautomerase (DDT) in Cancer." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1497113473427922.
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Chung, Ming Kei. "Assessment of phytotoxic effects of PAHs and DDTs in solid-phase system using microalgal bioassays." HKBU Institutional Repository, 2005. http://repository.hkbu.edu.hk/etd_ra/628.
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