Made available in DSpace on 2014-12-17T15:01:16Z (GMT). No. of bitstreams: 1 DannielleJS.pdf: 1624896 bytes, checksum: 0e96250738f2bfbc525b251adc249965 (MD5) Previous issue date: 2008-12-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The decontamination of the materials has been subject of some studies. One of the factors that it increases the pollution is the lack of responsibility in the discarding of toxic trash, as for example the presence of PCB (Polychlorinated Biphenyls) in the environment. In the Brazilian regulations, the material contaminated with PCB in concentrations higher than 50 ppm must be stored in special places or destroyed, usually by incineration in plasma furnace with dual steps. Due to high cost of the procedure, new methodologies of PCBs removal has been studied. The objective of this study was to develop an experimental methodology and analytical methodology for quantification of removal of PCBs through out the processes of extractions using supercritical fluid and Soxhlet method, also technical efficiency of the two processes of extraction, in the treatment of contaminated materials with PCBs. The materials studied were soils and wood, both were simulated contamination with concentration of 6.000, 33.000 and 60.000 mg of PCB/ kg of materials. Soxhlet extractions were performed using 100 ml of hexane, and temperature of 180 ?C. Extractions by fluid supercritical were performed at conditions of 200 bar, 70?C, and supercritical CO2 flow-rate of 3 g/min for 1-3 hours. The extracts obtained were quantified using Gas chromatography-mass spectrometry (GC/MS). The conventional extractions were made according to factorial experimental planning technique 22, with aim of study the influence of two variables of process extraction for the Soxhlet method: contaminant concentration and extraction time for obtain a maximum removal of PCB in the materials. The extractions for Soxhlet method were efficient for extraction of PCBs in soil and wood in both solvent studied (hexane and ethanol). In the experimental extraction in soils, the better efficient of removal of PCBs using ethanol as solvent was 81.3% than 95% for the extraction using hexane as solvent, for equal time of extraction. The results of the extraction with wood showed statistically it that there is not difference between the extractions in both solvent studied. The supercritical fluid extraction in the conditions studied showed better efficiency in the extraction of PCBs in the wood matrix than in soil, for two hours extractions the obtain percentual of 43.9 ? 0.5 % for the total of PCBs extracted in the soils against 95.1 ? 0,5% for the total of PCBs extracted in the wood. The results demonstrated that the extractions were satisfactory for both technical studied / A descontamina??o de materiais tem sido tema de v?rios estudos. Um dos fatores que aumenta a polui??o ? a falta de responsabilidade no descarte do lixo t?xico, como por exemplo, a presen?a de PCBs (Bifenilas policloradas) no meio ambiente. Nos regulamentos brasileiros, o material contaminado com PCBs nas concentra??es acima de 50 ppm deve ser armazenado em lugares especiais ou ser destru?do, geralmente por incinera??o em forno de plasma com duplo est?gio. Devido ao custo elevado deste processo, novas metodologias para remo??o de PCBs est?o sendo pesquisadas. O objetivo deste estudo foi desenvolver uma metodologia experimental e anal?tica para a quantifica??o da remo??o de PCBs de materiais contaminados atrav?s de extra??o pelo m?todo Soxhlet e por flu?do supercr?tico, como tamb?m avaliar e comparar a efici?ncia t?cnica dos dois processos de extra??o. Os materiais avaliados foram: solo e madeira ambos contaminados com PCBs via contamina??o simulada. Os materiais foram contaminados com a concentra??o de 6.000, 33.000 e 60.000 mg de ?leo Ascarel/ kg de material. A extra??o pelo m?todo Soxhlet foi realizada usando 100 mL de solvente org?nico (hexano ou etanol), 180 ?C e press?o atmosf?rica. A extra??o com flu?do supercr?tico foi realizada nas seguintes condi??es: 200 bar, 70 ?C e 3 g de CO2 / min. Os extratos obtidos foram quantificados usando a cromatografia gasosa acoplada a um espectr?metro de massa (CG-EM). Foram realizadas extra??es pelo m?todo convencional usando a t?cnica de planejamento fatorial 22, com a finalidade de estudar os efeitos da concentra??o inicial de contaminante e o tempo de extra??o no percentual de remo??o de PCBs. As extra??es pelo m?todo Soxhlet foi eficiente para extra??o de PCBs em solo e em madeira para os dois solventes em estudo (hexano e etanol). Nos experimentos de extra??o em solos, o melhor percentual de remo??o de PCBs usando etanol como solvente foi de 81,3% e 95% para a extra??o que usa hexano como solvente, com o mesmo tempo de extra??o. Os resultados dos ensaios de extra??o com madeira, mostraram que estatisticamente n?o h? diferen?a entre as extra??es mudando o solvente. A extra??o por fluido supercr?tico nas condi??es estudadas teve melhor desempenho para extrair PCBs na matriz madeira do que no solo. Em duas horas de extra??o foi obtido percentual de 43,9 ? 0,5 % para a soma do total de PCBs extra?do no solo contra 95,1 ? 0,5 % para a soma total de PCBs extra?do na madeira. Os resultados foram satisfat?rios para ambas as t?cnicas de extra??o estudadas

Devido à alta toxicidade, a produção e comercialização dos PCBs (Polychlorinated Biphenyls - Bifenilas Policloradas) estão proibidas no mundo todo. Esses compostos foram utilizados principalmente como base de misturas comerciais em óleos dielétricos para transformadores e capacitores. Hoje existem diversas áreas contaminadas com essas substâncias que são de difícil degradação ocasionada pela sua elevada estabilidade térmica e química. Há diversos estudos sobre diferentes técnicas de tratamento de áreas contaminadas por PCBs. A técnica proposta nesse trabalho foi a de oxidação química através do reagente de Fenton. Para isso, foi simulado em laboratório experimentos de tratamento de solo contaminados artificialmente por ascarel (mistura comercial de PCBs). A oxidação foi realizada segundo a técnica do planejamento experimental fatorial de dois níveis e duas variáveis. Manteve-se constante a concentração do contaminante - em torno de 6000 mg de PCB/ kg de solo - e variou-se a concentração de Fe2+ (0,04 a 0,1 mol/L) e H2O2 (2,07 a 4,15 mol/L). Os ensaios foram realizados ainda nos seguintes tempos de reação: 0, 5, 24 e 48 horas. A análise dos dados foi realizada através de cromatografia gasosa acoplada a um espectrômetro de massa - GC/MS. Dos resultados, concluiu-se que o experimento cuja concentração do reagente de Fenton era 4,15 mol/L de H2O2 e 0,04 mol/L de Fe2+, apresentou melhor percentual de remoção, em torno de 76% para o pentaclorobifenila, 67% para o hexaclorobifenila e 72% para o heptaclorobifenila. Além disso, observou-se que, dentro da região experimental estudada, o efeito da concentração de íons ferrosos foi mais significativo do que o causado pela concentração de peróxido de hidrogênio e que o mesmo tem um efeito negativo pois aumentando a concentração dos íons ferrosos diminui-se a remoção dos contaminantes. / Production and trading of polychlorinated biphenyls (PCBs) are prohibited at whole world due to their high toxicity. They were used mainly as dielectric oils for transformers and capacitors. Recently there are many contaminated areas with these compounds. The high thermic and chemistry stability of PCBs are responsible for their hard degradation. Many studies have been conducted about several techniques of soil remediation. The main purpose of this research is to study chemical oxidation using Fenton\'s reagent to soils treatment. It was simulated in laboratory experiments of soil treatment which was artificially contaminated with Ascarel (PCBs commercial mixture). Process oxidation was made according to factorial experimental planning technique of two levels and two variables (22). The contaminant concentration was constant - 6000 mg PCB/ kg soil - and it was varied the Fe2+ concentration (0,04 mol/L to 0,10 mol/L) and H2O2 concentration (2,07 mol/L to 4,15 mol/L). The times reaction of experiments were: 0, 5, 24 and 48 hours. It was used gas chromatography coupled with mass spectrometer - GC/MS. The better result shown removal rate of 76% to pentachlorobiphenyl, 67% to hexachlorobiphenyl and 72% to heptachlorobiphenyl, experimental conditions were Fe2+ concentration of 0,04 mol/L and H2O2 concentration of 4,15 mol/L. Besides it was observed that studied region the concentration effect of ferrous ions was more significant than concentration effect of hydrogen peroxide. The concentration effect of ferrous ions was negative on system because removal rate of contaminants decreases when [Fe2+] increases.

Objectives were to: (1) assess toxicity of polychlorinated biphenyls on Eisenia foetida, in terms of survival (LC5O/LD5O), and suppression of coelomocytes to form secretory (SR) and erythrocyte rosettes (ER) with, and to phagocytize rabbit erythrocytes; and (2) compare results with those of Lumbricus terrestris to assess relative sensitivities to PCB. Using 5-d filter paper contact exposure protocol, LC50 and LD50 were 30.4 cg/cm2 and 4450 cg/g dry mass, respectively. Nominal PCB exposure concentrations of 5.0 and 10.0 pg/cm2 resulted in tissue levels of 1389 and 2895 pg/g dry mass causing a significant reduction in SR formation by 18 and 52%, respectively. ER formation and phagocytosis were reduced significantly (52 and 61%) only at the higher tissue concentration. Compared to reported data on lethality and immunomodulation in L. terrestris, E. foetida appears to be more resistant.

No description available.

This paper uses the case of Polychlorinated Biphenyls (PCBs) to examine the dynamics of the public policy cycle in Canada. A process approach is applied to examine the principal stages of the cycle: problem identification, agenda-setting, decision-making, and implementation. In examining these stages, the factors that drive the policy cycle and those that impede its progress are identified. The regulatory history of PCBs is traced to demonstrate some of the complexities of the policy cycle. As one of the better known hazardous wastes in Canada, PCBs have been the catalyst for the introduction of new toxic chemical regulations throughout the 1970s and 1980s. Since the late 1970s, regulatory policies have been developed and implemented for PCB use and handling. After major PCB accidents occurred during the second half of the 1980s, regulations were introduced for their transport, storage and disposal. This case study provides seven major conclusions: (1) before the right policy solution is found and implemented, several stages in the cycle may need to be repeated; (2) public perception is a key determinant of the policy problem; (3) focusing events are a critical factor in setting the agenda; (4) decision-making often takes an incremental approach due to incomplete information and divided policy jurisdictions; (5) successful implementation, particularly in divided jurisdictions, requires sympathetic officials who are supportive of the enabling legislation; (6) constituency group support is a necessary condition for policy implementation; and (7) to deal with public concerns which may impede the implementation process, officials need political and managerial skills. / Arts, Faculty of / Political Science, Department of / Graduate

No description available.

IntroductionEndocrine disrupting chemicals (EDCs) are agents, found either singly or used in mixtures, that disrupt the endocrine system or its production of hormones and may cause adverse effects in the exposed individuals or populations and, in the case of pregnant women, their offspring. It is presumed that maternal thyroid hormones contribute to fetal brain development. The EDCs that could impair maternal thyroid hormone function might result in subtle deficits in neurodevelopmental outcomes in children. Polychlorinated biphenyls (PCBs) are a class of EDCs produced in the past century and are still found in the environment. This dissertation aims to explore, elaborate, and embellish the associations between prenatal exposure to PCBs, the metabolites associated with PCBs, and child cognitive and motor development. The next aim of this dissertation is to explore the associations between prenatal exposure to PCBs, the metabolites associated with PCBs, and maternal thyroid hormones. Five chapters are included in this dissertation: First, an introduction to PCBs and specific aims; second, a systematic review of the literature, including the studies where prenatal exposure to PCBs or the hydroxylated PCB metabolites (OH-PCBs) and their relationship with various domains of children's neurodevelopment were investigated; third, an empirical study of exploring the associations between prenatal exposure to a mixture of PCB, OH-PCBs and children cognitive and motor skills measured in different ages; fourth, an empirical study of investigating the associations between prenatal exposure to a mixture of PCB, OH-PCBs and maternal thyroid hormones with potential for investigating the mediation of possible associations observed in the third chapter by maternal thyroid hormone concentrations; fifth, a discussion of the findings, implications for public health research, and practice and conclusions. Materials and Methods The systematic review included peer-reviewed studies indexed in several repositories (N=71 studies) from the inception of the repositories. This systematic review of the studies measured the PCBs directly in prenatal or immediately after delivery in maternal serum, cord blood, placenta, or breast milk. The empirical studies used the data available on mothers and children from "Child Health and Development Studies." Eleven PCB congeners and five OH-PCB metabolites were measured in the maternal serum post-partum among a random subset of the participants. I used a mixture analysis, Bayesian Kernel Machine Regression (BKMR), and generalized linear models (GLM) to assess the association between concentrations of PCB congeners and OH-PCB metabolites measured three days post-partum and children's cognitive and motor skills scores at age five, and cognitive skills measured at a follow-up at ages 9-11. BKMR and GLM were also used to explore the associations between PCB congeners and OH-PCB metabolites and maternal free thyroxine (FT4) and thyroid-stimulating hormone (TSH). Results The systematic review found that prenatal exposure to PCBs was possibly associated with poor cognitive development and poor attention in early and middle childhood. The evidence regarding motor development, behavior, and other neurodevelopmental outcomes were not conclusive at any stage in childhood. There was an indication for sex-specific associations with worse cognition and attention scores among boys. There was also evidence in individual studies regarding the possible association between prenatal exposure to OH-PCBs and neurodevelopmental outcomes. There were significant differences between the studies in markers of exposure, exposure assessment timing, outcome assessment, and the methodological approaches to assess the association. In the second empirical study, I found that in the crude and adjusted BKMR models among the OH-PCB metabolites, cognitive skills test scores at age five increased with each decile increase in the mixture of OH-PCB metabolites compared to when all of the metabolites were fixed at their 50th percentile among all the children and the boys and girls. These associations were largely driven by OH-PCB153 and OH-PCB146, metabolites associated with the congener PCB153. In the third empirical study, among OH-PCB metabolites attributed to PCB congeners, I observed suggestive evidence for a positive association with maternal FT4, particularly in the highest percentile of exposure to overall OH-PCB metabolites. I did not observe an association between exposure to the mixture of PCB congeners and Maternal FT4 or TSH. Nonetheless, the overall patterns suggested a positive association between exposure to PCB congeners and maternal FT4.No associations of the overall mixture of PCBs and OH-PCB metabolites were observed with maternal TSH concentrations in the BKMR models. Nonetheless, in single metabolite risk estimates, I found that 3’-OH-PCB138 was positively associated with maternal TSH values when the 3’-OH-PCB138 was fixed at its 90th percentile compared to when it was in its 10th percentile, fixing all the other congeners in their 10th, 50th, and 90th percentiles. Finally, there was an indication of a possible antagonistic interaction between 4-OH-PCB107 and 3’-OH-PCB-138 in the association of OH-PCBs with maternal FT4 such that 3’-OH-PCB138 tended to have a positive association with maternal FT4 when 4-OH-PCB107 was fixed in the 90th percentile and tended to have a negative association with maternal FT4 when 4-OH-PCB107 was fixed in their 10th percentile when all the other metabolites were fixed in their median value. Conclusions There were patterns of positive associations of OH-PCB metabolites with the children’s cognitive outcomes and maternal FT4 and maternal TSH. Nonetheless, the observed associations were weak in magnitude, often including the null value. The BKMR allowed me to explore and investigate the interactions between different components of the mixture and the overall mixture effect on the outcomes. My dissertation indicated the necessity of a holistic approach to address the impact of exposure to environmental toxins, specifically due to the detected findings regarding interactions between OH-PCB metabolites.

Estrogen-regulated synthesis of vitellogenin (Vg), a yolk-protein precursor required for reproduction, was monitored to explore the potential antiestrogenic effects of the coplanar polychlorinated biphenyl (PCB), 3,3',4,4',5,5'-hexachlorobiphenyl (3,4,5-HCB), in juvenile rainbow trout (Oncorhynchus mykiss). The effects of 17β-estradiol on 3,4,5-HCB induction of cytochrome P4501A (CYP1A) were also examined. Trout were injected with 3,4,5-HCB (0.25, 2.5, 25, 50, or 100 mg/kg) or a vehicle control, and after 10 weeks, they were sampled or injected with 17β-estradiol (0.1 mg/kg). Markers of vitellogenesis, such as liver somatic index, hepatic estrogen- binding sites, and plasma Vg concentrations, in 17β-estradiol-treated fish were not affected by 3,4,5-HCB. Maximal induction of CYP1A protein and mRNA occurred at doses above 2.5 mg/kg, and 17β-estradiol reduced CYP1A protein content at a single dose (0.25 mg 3,4,5-HCB/kg). Ethoxyresorufin-O-deethylase (EROD) activity was induced by 3,4,5-HCB doses of between 0.25 and 2.5 mg/kg, but induction was reduced at higher doses, indicating that 3,4,5-HCB suppressed CYP1A catalytic activity. In 3,4,5-HCB/17β-estradiol-treated fish, plasma estradiol was significantly reduced at 100 mg 3,4,5-HCB/kg, but the depression was not associated with CYP1A induction or with other antiestrogenic effects. Although CYP1A was induced, 3,4,5-HCB did not interfere with vitellogenesis, which suggests that the PCB congener is not a potent antiestrogen in rainbow trout.

For more than 50 years, heavy metal exposure during pre- or post-natal ontogeny has been known to produce long-lived hyperactivity in rodents. Global brain injury produced by neonatal hypoxia also produced hyperactivity, as did (mainly) hippocampal injury produced by ontogenetic exposure to X-rays, and (mainly) cerebellar injury produced by the ontogenetic treatments with the antimitotic agent methylazoxymethanol or with polychlorinated biphenyls (PCBs). More recently, ontogenetic exposure to nicotine has been implicated in childhood hyperactivity. Because attention deficits most often accompany the hyperactivity, all of the above treatments have been used as models of attention deficit hyperactivity disorder (ADHD). However, the causation of childhood hyperactivity remains unknown. Neonatal 6-OHDA-induced dopaminergic denervation of rodent forebrain also produces hyperactivity - and this model, or variations of it, remain the most widely-used animal model of ADHD. In all models, amphetamine (AMPH) and methylphenidate (MPH), standard treatments of childhood ADHD, typically attenuate the hyperactivity and/or attention deficit. On the basis of genetic models and the noted animal models, monoaminergic phenotypes appear to most-closely attend the behavioral dysfunctions, notably dopaminergic, noradrenergic and serotoninergic systems in forebrain (basal ganglia, nucleus accumbens, prefrontal cortex). This paper describes the various pharmacological models of ADHD and attempts to ascribe a neuronal phenotype with specific brain regions that may be associated with ADHD.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2012. / Polychlorinated biphenyls (PCBs) are known harmful chemicals which require urgent remediation, monitoring and assessment in the environment. The predominant current methods used to analyze PCBs involve expertise and are cost intensive. Most of these methods are chromatographic based techniques which are difficult to sustain in Africa due to the expensive nature of the instrument, costly running expenses and skilled labour required. These limitations face Africans, who are the most affected by the presence of PCBs in their environment as a result of improper disposal and usage of these compounds.