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No description available.

Dichloro-diphenyl-trichlorethane (DDT) is a chemical used in malaria control through indoor residual spraying (IRS) and has saved numerous lives in the past six decades. DDT use is restricted/banned under the Stockholm Convention on Persistent Organic Pollutants. Passive air sampling using polyurethane foam was conducted in South Africa to evaluate the presence and trends of DDT and its metabolites. Three sampling sites were used, namely, Barberspan Nature Reserve (rural agricultural), Vanderbijlpark (urban industrial) and Molopo Nature Reserve (isolated nature reserve). Sampling was conducted for a period of one year in 2008. Back trajectories from the three sampling sites were generated using HYSPILT to determine the sources of DDT metabolites to the sampling areas. Forward trajectories were also generated to determine the movement, distribution, and fate of DDT from the areas under Indoor residual spray of DDT for malaria control in South Africa and Swaziland. Chemical analysis was conducted by the RECETOX (Mazaryk University) in the Czech Republic. DDT metabolites (o,p’-DDE, p’p’-DDE, o.p’-DDD, p,p’-DDD, o,p’-DDT p,p’-DDT) were analysed using a GC-ECD (HP 5890). Vanderbijlpark had the highest concentrations of DDT metabolites throughout the year. Barberspan had the second highest concentration and Molopo the least. Seasonal changes in concentration were much the same at the three sites. %p,p’-DDT of ΣDDT is consistent with IRS spraying months in South Africa and Swaziland. A combinations of backward and forward trajectories, together with the temporal pattern of change of the %p,p’-DDT of ΣDDT support the deduction that DDT sampled from the three study sites (to some degree) came from IRS areas in South Africa and Swaziland. The presence of DDT in Molopo Nature Reserve and Barberspan is evidence of long-range transportation over dry semi-desert areas. Back-trajectories indicate the possible source of DDT were the IRS areas in the provinces of Limpopo, Mpumalanga, and KwaZulu-Natal. Some air masses to the sampling sites came from the sprayed areas. The forward trajectories also revealed that the DDT sprayed during IRS could undergo LRT. The DDT metabolites were able to travel to neighbouring countries such as Mozambique, Namibia, Zimbabwe and Botswana. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Dichloro-diphenyl-trichlorethane (DDT) is a chemical used in malaria control through indoor residual spraying (IRS) and has saved numerous lives in the past six decades. DDT use is restricted/banned under the Stockholm Convention on Persistent Organic Pollutants. Passive air sampling using polyurethane foam was conducted in South Africa to evaluate the presence and trends of DDT and its metabolites. Three sampling sites were used, namely, Barberspan Nature Reserve (rural agricultural), Vanderbijlpark (urban industrial) and Molopo Nature Reserve (isolated nature reserve). Sampling was conducted for a period of one year in 2008. Back trajectories from the three sampling sites were generated using HYSPILT to determine the sources of DDT metabolites to the sampling areas. Forward trajectories were also generated to determine the movement, distribution, and fate of DDT from the areas under Indoor residual spray of DDT for malaria control in South Africa and Swaziland. Chemical analysis was conducted by the RECETOX (Mazaryk University) in the Czech Republic. DDT metabolites (o,p’-DDE, p’p’-DDE, o.p’-DDD, p,p’-DDD, o,p’-DDT p,p’-DDT) were analysed using a GC-ECD (HP 5890). Vanderbijlpark had the highest concentrations of DDT metabolites throughout the year. Barberspan had the second highest concentration and Molopo the least. Seasonal changes in concentration were much the same at the three sites. %p,p’-DDT of ΣDDT is consistent with IRS spraying months in South Africa and Swaziland. A combinations of backward and forward trajectories, together with the temporal pattern of change of the %p,p’-DDT of ΣDDT support the deduction that DDT sampled from the three study sites (to some degree) came from IRS areas in South Africa and Swaziland. The presence of DDT in Molopo Nature Reserve and Barberspan is evidence of long-range transportation over dry semi-desert areas. Back-trajectories indicate the possible source of DDT were the IRS areas in the provinces of Limpopo, Mpumalanga, and KwaZulu-Natal. Some air masses to the sampling sites came from the sprayed areas. The forward trajectories also revealed that the DDT sprayed during IRS could undergo LRT. The DDT metabolites were able to travel to neighbouring countries such as Mozambique, Namibia, Zimbabwe and Botswana. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

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Background: The synthetic insecticide DDT (dichlorodiphenyltrichloroethane) has been speculated to increase breast cancer risk due to its environmental persistence, levels of bioaccumulation in breast adipose tissue, and endocrine disrupting actions. Epidemiological studies have had inconsistent findings, however a study in MMTV-neu mice determined that localized, developmental exposure to the reported anti-androgen p,p' DDE accelerated mammary tumor development. This study tested the potential cancer-promoting actions of p,p' DDE, the most prevalent and persistent DDT metabolite. <br>Objectives: To identify and characterize the expression of p,p' DDE -regulated genes to determine how developmental exposure may influence mammary tissue to promote tumor formation. Methods: For localized delivery, ELVAX 40P pellets containing various doses of p,p' DDE, hydroxyflutamide (another anti-androgen), and mixtures of p,p' DDE with other congeners like o,p' DDE and p,p' DDT were implanted into the mammary fatpads of prepubertal female mice. p,p' DDE-regulated genes were identified by microarray analysis and analyzed by real time RT-PCR. <br>Results: Lipid-adjusted levels of p,p' DDE in mammary adipose tissue and serum in young mice were within the ranges of human exposure. p,p' DDE significantly upregulated casein gamma (csn1s2a ), keratin 18 (krt18) and interferon-induced protein 44 (ifi44) genes in mammary tissue. These genes were similarly, but not significantly regulated by hydroxyflutamide. The dose of p,p' DDE that caused early tumor onset in a previous study resulted in unique expression for all three genes and concentrations of p,p' DDE also influenced gene responses for the mixtures. However, no qualitative changes were observed in gland morphology. Significant upregulation of transforming growth factor beta (tgfb1) and downregulation of interleukin 10 (il10) in splenic leukocytes indicated that localized delivery of p,p' DDE to the mammary gland also influences systemic immune responses. Significant upregulation of il10 by p,p' DDE and hydroxyflutamide suggest that some of p,p' DDE actions may be through its anti-androgenic activity. <br>Conclusions: Relevant human exposure levels of p,p' DDE induce significant increases in expression of csn1s2a, krt18 and ifi44. This activity as well as those induced by other doses, ratios and hydroxyflutamide suggest p,p' DDE actions may involve anti-androgenic activity and influence local and systemic effects in a HER2+ breast cancer mouse model. / Mylan School of Pharmacy and the Graduate School of Pharmaceutical Sciences / Pharmacology-Toxicology / PhD / Dissertation

Although the pesticide DDT has been banned from use in Canada for more than three decades, DDT still persists in Canadian farmlands at detectable levels. Much effort, such as incineration, thermal desorption, and bioremediation, has been used to remediate DDT contaminated soils, but so far it is either too expensive or impractically slow. In this study, a three-year period of field trials was performed to investigate phytoremediation of DDT contaminated soil. In the field trials, millet, fall rye, sugar beet, potato, and pumpkin, treated with plant growth-promoting rhizobacteria (PGPR) were planted on two sites. As well, untreated plants were planted as a control. Plant growth, and 4,4’-DDT plus 4,4’-DDE concentrations in plant tissues and soil were monitored regularly. Comparing the plant growth between PGPR treated and untreated, PGPR significantly promoted the plant growth. On site 1, the root length and root weight of fall rye treated with PGPR were 16% and 44% greater, respectively, compared to the untreated plants. The root and shoot dry weights of millet treated with PGPR were 38% and 47% greater than those untreated plants. Root dry weight of sugar beet treated with PGPR was increased by 74% compared to untreated sugar beet. A significant effect of growth promotion was also observed in pumpkin and potato treated with PGPR. Following plant growth, DDT detection in plants was performed. 4,4’-DDT and 4,4’-DDE were found in plant tissues of fall rye, millet, sugar beet, and pumpkin. The concentrations of 4,4’-DDT and 4,4’-DDE in fall rye roots were 0.61 and 0.59 μg/g, respectively. In pumpkin tissues at harvest, 4,4’-DDT and 4,4’-DDE concentrations were 0.67 and 1.64 μg/g in roots, 1.06 and 2.05 μg/g in the lower stems, and 0.2 and 0.32 μg/g in the upper stems. The data indicated that it is feasible to phytoremediate DDT from contaminated soil. In addition, 4,4’-DDT concentrations in soils with different plant species were determined. In millet plot on site 1, 4,4’-DDT concentration in rhizosphere soil dropped by 41% in 2006 compared to 4,4’-DDT concentration at t0. In sugar beet plot on site 1, 28% of 4,4’-DDT dropped in rhizosphere soil in 2007. In pumpkin plot on site 1, 4,4’-DDT in rhizosphere soil was decreased by 22% in 2007. The results show that 4,4’-DDT concentration in rhizosphere soil was significantly lower than the initial level of DDT. Based on the data of 4,4’-DDT in soils and plant tissues, a mass balance was constructed and calculated. The preliminary mass balance shows that the total amount that DDT decreased in rhizopshere soil approximately equals to the total amount of DDT accumulated in plant tissues. This indicates that phytoextraction is the mechanism of DDT phytoremediation. In addition, PGPR promoted plant growth and then enhanced the phytoremediation efficiency of DDT. Therefore, the research indicates that PGPR assisted phytoremediation has a great potential for remediation of DDT and other chlorinated aromatics from impacted soil.

Although the pesticide DDT has been banned from use in Canada for more than three decades, DDT still persists in Canadian farmlands at detectable levels. Much effort, such as incineration, thermal desorption, and bioremediation, has been used to remediate DDT contaminated soils, but so far it is either too expensive or impractically slow. In this study, a three-year period of field trials was performed to investigate phytoremediation of DDT contaminated soil. In the field trials, millet, fall rye, sugar beet, potato, and pumpkin, treated with plant growth-promoting rhizobacteria (PGPR) were planted on two sites. As well, untreated plants were planted as a control. Plant growth, and 4,4’-DDT plus 4,4’-DDE concentrations in plant tissues and soil were monitored regularly. Comparing the plant growth between PGPR treated and untreated, PGPR significantly promoted the plant growth. On site 1, the root length and root weight of fall rye treated with PGPR were 16% and 44% greater, respectively, compared to the untreated plants. The root and shoot dry weights of millet treated with PGPR were 38% and 47% greater than those untreated plants. Root dry weight of sugar beet treated with PGPR was increased by 74% compared to untreated sugar beet. A significant effect of growth promotion was also observed in pumpkin and potato treated with PGPR. Following plant growth, DDT detection in plants was performed. 4,4’-DDT and 4,4’-DDE were found in plant tissues of fall rye, millet, sugar beet, and pumpkin. The concentrations of 4,4’-DDT and 4,4’-DDE in fall rye roots were 0.61 and 0.59 μg/g, respectively. In pumpkin tissues at harvest, 4,4’-DDT and 4,4’-DDE concentrations were 0.67 and 1.64 μg/g in roots, 1.06 and 2.05 μg/g in the lower stems, and 0.2 and 0.32 μg/g in the upper stems. The data indicated that it is feasible to phytoremediate DDT from contaminated soil. In addition, 4,4’-DDT concentrations in soils with different plant species were determined. In millet plot on site 1, 4,4’-DDT concentration in rhizosphere soil dropped by 41% in 2006 compared to 4,4’-DDT concentration at t0. In sugar beet plot on site 1, 28% of 4,4’-DDT dropped in rhizosphere soil in 2007. In pumpkin plot on site 1, 4,4’-DDT in rhizosphere soil was decreased by 22% in 2007. The results show that 4,4’-DDT concentration in rhizosphere soil was significantly lower than the initial level of DDT. Based on the data of 4,4’-DDT in soils and plant tissues, a mass balance was constructed and calculated. The preliminary mass balance shows that the total amount that DDT decreased in rhizopshere soil approximately equals to the total amount of DDT accumulated in plant tissues. This indicates that phytoextraction is the mechanism of DDT phytoremediation. In addition, PGPR promoted plant growth and then enhanced the phytoremediation efficiency of DDT. Therefore, the research indicates that PGPR assisted phytoremediation has a great potential for remediation of DDT and other chlorinated aromatics from impacted soil.