Browsing by Subject "Pollutants"
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Item Heavy metal and arsenic bioaccumulation in small mammals inhabiting the Anaconda Smelter Superfund Site, Montana(Texas Tech University, 2004-08) Reynolds, Kevin D.A key component in accurately assessing bioavailability of environmental metals at large National Priority List (NPL) sites is a reduction of uncertainty within exposure estimates. This reduction in uncertainty can be facilitated by collecting empirical data from individual animals inhabiting hazardous waste sites. Site-specific metal bioavailability data are also useful in supporting decisions regarding clean up and demediation, and regulators and scientists also support the use of these data in their exposure assessment models. However, rarely are data available to confirm modeled results. The primary objective of this study was quantifying the site-specific bioavailability and accumulation of heavy metals and arsenic in small mammals inhabiting a metals-contaminated NPL hazardous waste site in southwest Montana Deer mice (Peromyscus maniculatus) and northern pocket gophers (Thomomys talpoides) inhabiting areas contaminated with a gradient of heavy metals and arsenic were collected from the Anaconda Smelter SuperfUnd Site, Montana, USA. A total of 299 deer mice were collected in 1999 and 2000. Arsenic (As), cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn) were determined in blood, kidney, liver, mammary tissue, carcass, and stomach contents and compared to metal levels in the soils across six respective trapping grids established on spontaneously revegetated areas of the site. Among deer mouse stomach contents and tissues, only Zn and Cu were detected with regularity in all tissues. Lead and As were detected primarily in carcass samples, and Cd was detected most frequently in liver and kidney samples. Among all tissues analyzed, there were no differences (p > 0.05) between male and female mice for any of the metals except for Pb. When all mice were grouped by sex, there was a larger (p = 0.0380) proportion of female liver samples with detectable concentrations of Pb compared to males. Differences between adult and nonadult mice were mostly observed for Pb, Cd and As concentrations in kidney, liver and carcass samples.Item Indoor air quality in retail stores(2011-05) Rhodes, Joshua Daniel; Siegel, Jeffrey A.; Xu, YingRetail stores are understudied given the energy, occupant health, and potential sales impacts associated with poor indoor air quality (IAQ). There is also evidence of elevated pollutants in retail environments. This thesis is an exploration of the indoor air quality of retail stores. The first section of this thesis is a literature review on field investigations of the indoor air quality in retail buildings. Sixteen investigations report different measurements in 17 specific types of retail environments. Measurements vary depending on the specific investigation, but include VOCs, SVOCs, particles, microbiological species, and radon. When reported, indoor to outdoor ratios of almost all pollutants are greater than unity, suggesting the importance of indoor sources in retail environments. The second section of this thesis is an analysis of the whole store net emission factor for different retail environments. From the types of pollutants found in the retail store investigations, VOCs were the only pollutant group studied frequently enough to merit this analysis. The final section is an analysis of the potential for pollutant remediation strategies. Two methods, increasing air change rate and air cleaning, are considered with an analysis of the energy penalties associated with each.Item Oxidative destruction of organic contaminants utilizing ultrasound(Texas Tech University, 1996-08) Fahrenkrog-Hallman, Erin ElizabethMankind, over the many years of the industrial age, has made and utilized many useful chemicals. Not all of these chemicals are benign, and it becomes a particular problem when they come in contact with the environment. Whether or not the introduction of these chemicals into the environment was deliberate, mankind has a duty to address and solve these contamination problems.Item The effects of environmental pollutants on steroidogenesis and steroidogenic acute regulatory protein expression(Texas Tech University, 2001-05) Walsh, Lance PatrickMany environmental pollutants disrupt male reproductive function, inhibit steroid hormone biosynthesis, reduce serum testosterone levels, and decrease sperm counts. Although a disruption in steroidogenesis may underlie toxicant-induced reproductive toxicity, the mechanism by which these compounds inhibit steroid production remains unclear. The steroidogenic acute regulatory (StAR) protein mediates the rate-limiting and acutely-regulated step in steroidogenesis, the transfer of cholesterol from the outer to the inner mitochondrial membrane where die cytochrome P450 side chain cleavage (P450scc) enzyme initiates the synthesis of all steroid hormones. We hypothesized that environmental toxicants block steroidogenesis by disrupting StAR protein expression for several reasons: first, in contrast to the steroidogenic enzymes which have long half-lives and are chronically regulated, StAR protein is not an enzyme, is acutely regulated, its active form is highly labile and it must be continuously synthesized for steroid production to persist. Second, because StAR protein mediates the rate-limiting step in steroidogenesis, steroid production is very sensitive to disruptions in its expression. Finally, recent studies suggest that some environmental pollutants inhibit steroidogenesis by reducing cholesterol availability, implicating StAR protein as a potential target for these compounds. Using mouse MA-10 Leydig tumor cells, we studied the effects of acute exposure (<4 h) to the organochlorine insecticide lindane (y-hexachlorocyclohexane; HCH), the organophosphate insecticide Dimethoate, the herbicide Roundup, and the imidazole antifungal drugs econazole and miconazole on: (1) steroid production, (2) total cellular protein synthesis, (3) StAR and steroidogenic enzyme activity and expression, and (4) protein kinase A (PKA) activity. Our studies demonstrate that these toxicants reversibly inhibited steroidogenesis without causing cell toxicity or affecting PKA activity. While lindane and Dimethoate reduced StAR protein expression by reducing StAR mRNA levels. Roundup, econazole and miconazole reduced StAR protein levels post-transcriptionally. Although Roundup and Dimethoate inhibited P450scc activity, a reduction in StAR protein expression alone could account for the effects of these compounds on steroidogenesis, suggesting that the inhibition of P450scc activity in these instances has little physiological significance, its activity being distal to StAR function. Our studies strongly suggest that several different classes of environmental pollutants inhibit steroidogenesis by reducing StAR protein expression, thus supporting our hypothesis.