Thesis (MTech. degree: Environmental Management.)--Tshwane University of Technology, 2012. / Determines the presence and levels of common brominated flame retardants (BFRs) in surface water and sediments in Jukskei River catchments with the aim of identifying potential pollution sources using Geographical Information System (GIS) land use map in order to provide baseline data required to protect water resources against such hazardous chemicals.

Thesis (DTech. degree: Environmental Management)--Tshwane University of Technology, 2012. / Discusses polybromobiphenyls (PBBs) and polybromodiphenyl ethers (PBDEs) are among brominated flame retardants commonly used as additive flame retardants and are now well-known pollutants. They can easily be released from household and office materials if present and tend to settle on dust. Of all the PBDEs congeners, the detection of BDE-209 is considerably more difficult than the lower congeners. Furthermore, there is no available data on the presence of PBBs and PBDEs in indoor dust in South Africa, and, therefore, it was deemed necessary to conduct the present study.

Thesis (Ph.D.)--University of Ottawa, 2008. / Includes bibliographies. Also available via the World Wide Web.

Thesis (Ph.D.)--University of Ottawa, 2008. / Includes bibliographies.

Os éteres de bifenilas polibromados (PBDEs) são largamente usados como retardadores de chama e têm sido detectados no sangue humano, tecido adiposo e leite materno devido às suas propriedades físico-químicas e bioacumuladoras e à sua elevada persistência no meio ambiente. Muitos estudos têm relatado toxicidade hepática relacionada à exposição aos PBDEs. Como efeitos citotóxicos são frequentemente associados à disfunção mitocondrial,no presente estudo, investigamos a toxicidade do BDE-47 em mitocôndrias isoladas de fígado de rato. Nos seguintes parâmetros: potencial de membrana mitocondrial, consumo de oxigênio, interação com a membrana mitocondrial, liberação de cálcio, inchamento mitocondrial e os níveis de ATP da suspensão mitocondrial com a finalidade de observar a capacidade do composto em interferir com a bioenergética da organela. Avaliou-se ainda a formação de espécies reativas de oxigênio (ROS), dos níveis de GSH/GSSG, níveis mitocondriais de grupos sulfidrila de proteínas e níveis mitocondriais de NAD(P)H com o intuito de analisar o estado redox mitocondrial. Os congêneres BDE-47 e BDE-99 foram avaliados em concentrações que variaram entre 0,1 e 50 ?mol/L. Os dois congêneres de PBDEsapresentaram toxicidade mitocondrial afetando todos os parâmetros que avaliam a bioenergética mitocondrial culminandoum uma depleção do ATP. Por outro lado, nos ensaios de avaliação do estresse oxidativo os PBDEs estudados não demonstraram qualquer efeito, no entanto, afetaram a cadeia respiratória mitocondrial, o que normalmente reflete em um acúmulo de espécies reativas de oxigênio. Estes resultados são explicados pelo mecanismo de ação destes compostos como retardante de chama, pois durante a combustão os retardantes de chama bromados realizam a neutralização de radicais livres (OHo e Ho). Conclui-se assim que os PBDEs podem levar à disfunção bioenergética e assim induzir a morte celular pela diminuição do ATP. Observou-se ainda que BDE-47 apresentou maior toxicidade do que o BDE-99 sobre os parâmetros estudados. / Polybrominated biphenyls ethers (PBDE) , widely used as flame retardants, have been detected in human blood, adipose tissue and breast milk due to their physicochemical and high bioaccumulative properties and environmental persistence. Many studies have reported liver toxicity related to exposure to PBDEs. As cytotoxic effects are often associated with mitochondrial dysfunction,in the present study, we investigated the toxicity of the BDE-47 and BDE-99 on isolated rat liver mitochondria. Assessing mitochondrial membrane potential, oxygen consumption, interaction with the mitochondrial membrane, calcium release, mitochondrial swelling and ATP levels of the mitochondrial suspension in order to observe the ability of the compounds to interfere with the bioenergetic organelle, and the formation of reactive oxygen species (ROS), GSH/GSSG levels, mitochondrial sulfhydryl groups and levels of mitochondrial NAD(P)H in order to analyze mitochondrial redox state. The congeners BDE-47 and BDE -99 were evaluated at concentrations ranging between 0.1 and 50 ?mol/L. Both PBDEs congeners showed mitochondrial toxicity affecting all parameters that assess mitochondrial bioenergetics and culminating with ATP depletion. On the other hand, no effect was observed in tests assessing oxidative stress, although they were able to inhibit the mitochondrial respiratory chain, which is usually reflected in an accumulation of reactive oxygen species. These results are explained by the mechanism of action of this compounds as flame retardants, because during the combustion brominated flame retardants perform the neutralization of free radicals (OHo and Ho). It follows that PBDEs can lead to mitochondrial dysfunction and thus induce bioenergetic cell death. It was also observed that The BDE-47 showed higher toxicity than BDE-99 in the studied model

Background: Polybrominated diphenyl ethers (PBDEs) are additive flame retardants which are found in household and commercial products. These chemicals have the potential to leach from the product into the environment. Human health effects include neurodevelopmental changes, low birth weight and thyroid hormone changes have also been reported, although continued research in this field is needed. Humans are exposed to PBDEs through various exposure pathways and recent studies have determined that exposure to household dust is also a significant route of exposure for humans. The purpose of this study was to access the risk for PBDE intake through an exposure assessment. Also, a laboratory protocol for the fractionation and determination of PBDEs in household dust was developed and evaluated. Methods: PBDE concentrations in indoor dust were measured and compared to previously published data on the topic. A laboratory protocol for fractionation of indoor dust and determination of PBDEs in indoor dust was developed. The new laboratory method was compared to a previously published lab procedure to determine its effectiveness. A p-value of <0.01 and 95% confidence intervals were used to determine statistical significance. Intake estimates were also determined for adults and children exposed at different rates. Results: PBDEs were detected in all the house dust samples with total concentrations (sum of 12 congeners) ranging from 2,870 to 50,642 ng/g dry mass. The averaged concentrations from the six replicate sieve fractions ranged from 106 to 5,697 ng/g dry weight. Daily dust intake rates, based on previously published estimates, range from 20 to 200 mg/day for children and 0.56 to 50 mg/day for adults. Low and high estimates of the daily intake of PBDEs in children and adults were calculated using the average concentration of total PBDEs found in house dust in this study. The exposure estimates for children were approximately 371 to 3,709 ng PBDEs daily based on a mean value of 18,546 ng/g dry weight. The estimate for adults was approximately 10.4 to 927 ng/g dry weight. Conclusions: The new laboratory protocol produces comparable results for QA/QC materials compared to a previously published protocol. Particulate size does not appear to be a significant factor in PBDE concentration and future analysis may only need dust particles to be sieved to one or two sizes (i.e. 500 um and 125 um). Based on the potential intake calculations for children and adults, dust appears to be a significant route of exposure for PBDEs and analysis of additional dust samples will broaden the scope of available data for this method.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 6 uppsatser.

Thesis (M.S.)--Villanova University, 2008. / Chemistry Dept. Includes bibliographical references.

Thesis (M.S.)--Villanova University, 2008. / Chemistry Dept. Includes bibliographical references.