Thesis (M.S.)--Bowling Green State University, 2006. / Document formatted into pages; contains xviii, 92 p. : ill. Includes bibliographical references.

Thesis (M.S.)--Bowling Green State University, 2006. / Document formatted into pages; contains ix, 85 p. : ill. Includes bibliographical references.

Thesis (M.S.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--University of Iowa, 2007. / Supervisor: Gabriele Ludewig. Includes bibliographical references (leaves 56-61).

Traditional assessments of contaminated sites require the collection and analysis of field media. Specifically, sediment analysis is used to determine type of contaminant as well as total contaminant concentrations (TCC). Although TCC can be used to determine if a site is contaminated, it is unable to adequately predict exposure and bioaccumulation in organisms. Biota-sediment accumulation factors were originally introduced to calculate and predict expected exposure to organisms based on sediment TCC. As they have been shown to be unreliable with field sediments, their use is limited. Alternatively, Tenax has been examined as a tool for measuring exposure to hydrophobic organic contaminants, where the Tenax extractable concentration is related to the bioaccumulated organism concentration. Although this relationship has been demonstrated in multiple studies, few have actually related the data from multiple sites to develop a standard model of Tenax accumulation. This research had two specific goals: Develop a literature based model of Tenax accumulation of polychlorinated biphenyl congeners (PCBs) and test it's applicability to field collected sediments from the Ottawa River (OR, Toledo OH, Chapter 2) and verify the use of the model in a highly-disturbed, post-dredge system, as well as the use of Tenax as an indicator of changes in bioavailability after dredging (Chapter 3). The literature-based complete Tenax model (TM) provided a strong model for the prediction of bioaccumulation in Lumbriculus variegatus (r2=0.91). When compared to the pre-dredge data from the OR, 95% of the data were encompassed by the CTM. No bias of the model was observed across homologue groups. Subsequently, the model was used with sediments collected after remediation via dredging from the OR. In this study, the CTM encompassed 73% of the data. Although all sites along the river were considered disturbed by the dredging, resuspension, and drift of sediments, data from sites that were less disturbed were better described by the model (86% versus 64% of dredged data). Overall, the CTM is recommended for use in the prediction of exposure and accumulation of PCBs in field sediments.

M.Tech. (Chemistry) / Please refer to full text to view abstract

M.S. / Bio-organic Chemistry / Single doses of tetrachlorobiphenyls, shown to be free of any chlorinated dibenzodioxins or dibenzofurans to a level of 1 ppm, were given to rhesus monkeys (Macaca mulatta) and the hepatic microsomal enzyme response measured periodically for 32 days. Liver biopsies, obtained by a closed needle technique, provided the tissue samples. Aryl hydrocarbon hydroxylase (measured as benzo[a]pyrene hydroxylase), aminopyrine - N - demethylase and cytochrome P-450 were measured on each sample. Animals treated with 25 mg/kg body weight of 2,5,2' ,5'- tetrachlorobiphenyl showed a marked increase in the demethylase activity, which peaked at 1 to 2 days after treatment, and had no effect on the x hydroxylase activity or the position of the absorption maximum of the CO difference spectrum of cytochrome P-450. This is phenobarbital like inductive behavior. The animals treated with 1 mg/kg body weight of 3, 4, 3’, 4’-tetrachlorobiphenyl showed a 3-methylcholanthrene type inductive profile. The hydroxylase activity was significantly increased and peaked at 2 days after treatment. The demethylase activity was not changed. The position of the cytochrome P-450 difference spectrum absorption maximum was shifted to 448 nm. The control animals received just the acetone / corn oil vehicle and showed no changes in any of the biochemical activities measured in the course of this experiment. This data supports the structure activity relationships, established in rats, for chlorobiphenyls as inducers of hepatic microsomal enzyme activity in rhesus monkeys.

Polychlorinated biphenyls (PCBs) are a class of bioactive chemical once used in industrial applications, but which now contaminate the world environment. PCBs are lipophilic with few natural degadatory mechanisms, and thus they accumulate in human and animal tissues, and are passed to subsequent generations via transfer between mother and offspring. Research has shown that PCBs can interfere with brain and sexual organ development, and adult sexual behaviors and reproduction. However, previous studies produced contradictory results based on the dose and method of administration, species, and the age at exposure. The research detailed in this thesis elucidates the effects of prenatal exposure to low levels of a commercial mixture of PCBs, Aroclor (A) 1221, on female reproductive function. The studies undertaken in this dissertation focus on three areas relevant to understanding long-term effects of PCBs on reproductive physiology in female rats: (1) developmental effects in two generations, (2) sexual behaviors in the first generation, and (3) gene expression in the first generation. In the first research section of this dissertation, the sexual and somatic development of PCB-exposed animals is investigated in first (F1) and second (F2) generation females. Dose-dependent effects are observed in both generations, and a greater number of endpoints are significantly affected in the F2, including circulating hormone levels and uterine and ovarian weight. The second research section of the dissertation explores whether sexual behaviors in the first generation of exposed animals are altered by A1221, using a paced mating paradigm designed to elucidate female-typical behaviors. Several salient behaviors are affected by PCB exposure, including likelihood to mate, mating trial pacing, and stress-related vocalizations. The third research chapter discusses the results of a genomewide microarray assay performed on the preoptic area of the brain. The preoptic area is a neuroendocrine control center implicated in regulation of reproductive physiology and behavior. Taken together, these results suggest that A1221 has long lasting and trans-generational effects on the development and behavior of exposed females, accompanied by altered gene expression in a neuroendocrine region of the brain. These findings have implications for female reproductive health and reproductive success in wildlife and humans.

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Environmental Sciences." Includes bibliographical references (p. 173-186).

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