M.Sc. (Zoology) / Axenic cultures of Euglena gracilis in different basal medium concentrations, to simulate eutrophic conditions, were exposed to different concentrations of Monocrotophos and Dichlorvos to determine the effect of the pesticides on the growth reaction. The effect of the pesticides on the chlorophyll a content of test organisms exposed to equivalent toxicities of pesticides was determined. The amount of pesticide accumulated and me tabolised was determined by the choline esterase method and by gaschromatography. More pesticide was found to be accumulated and metabolised by organisms in the lower concentration of basal medium.

M.Sc. (Zoology) / Blood samples were obtained from 42 Cape (Gyps coprotheres) Vultures during the period 1990 to 1991. Nestlings were sampled at two natural localities namely the Scheerpoort and Manoutsa colonies. Samples from captive birds ranging in age from immature to mature were obtained from four locations which include the Johannesburg Zoo, Tygerberg Zoo, De Wildt Cheetah Research and Breeding Station and World of Birds. The main objective of the study was to describe the population genetic structure of G. coprotheres by means of a protein electrophoretic examination. The optimum electrophoretic conditions were determined for maximum resolution of the protein systems examined. Allele frequency data assessed at 34 structural gene loci were obtained. As measures of variability, the perc~ntage polymorphic loci and average heterozygosity were calculated for the Cape vulture and values obtained were 11.76\ and 0.021 respectively. Both of the latter values are less than half the values reported for the majority of other avian species. The electrophoretic data were utilised in two population genetic simulation programmes and it was determined that the variation present in the populations of G. coprotheres studied may disappear within the next 35 generations. The blood samples were also subjected to a toxicological examination. Concentrations of DDT and its derivatives were measured by gaschromatographic analyses. Biocide levels were detected in ppb and adjusted to ppm by a conversion factor of 150. Quantifiable levels of DDT, DOD and DOE were detected in 72.4\, 60.0% and 89.7% of the individuals respectively. DOE is one of the major metabolites of DDT and the discussion was focused on levels thereof.

Environmental toxicologists and public health officials are responsible for assisting in the identification, management, and mitigation of public health hazards. As a result, there is a continued need for robust analytical tools that can aid in the rapid quantification and characterization of chemical exposure. In the first research phase, we demonstrated that a current tool for estimating human organophosphate pesticide exposure, measuring dialkyl phosphate (DAPs) metabolites in urine as chemical biomarkers of pesticide exposure, could represent exposure to DAPs themselves and not to pesticides. We showed that DAPs are metabolically stable, have high oral bioavailability, and are rapidly excreted in the urine following oral exposure. Results suggest that DAP measurements may lead to overestimates of human organophosphate pesticide exposure. In the second phase of research, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) based analytical method was developed and validated for quantifying polycyclic aromatic hydrocarbons (PAHs) in biotic matrices with fat contents that ranged from 3 to 11%. Our method improved PAH recoveries 50 to 200% compared to traditional QuEChERS methods, performed as well or better than state of the art Soxhlet and accelerated solvent extraction methods, had sensitivity useful for chemical exposure assessments, and reduced sample preparation costs by 10 fold. The validated QuEChERS method was subsequently employed in a human exposure assessment. Little is known about how traditional Native American fish smoke-preserving methods impact PAH loads in smoked foods, Tribal PAH exposure, or health risks. Differences in smoked salmon PAH loads were not observed between Tribal smoking methods, where smoking methods were controlled for smoking structure and smoke source. PAH loads in Tribally smoked fish were up to 430 times greater than those measured in commercially available smoked fish. It is not likely that dietary exposure to non-carcinogenic PAHs at heritage ingestion rates of 300 grams per day poses an appreciable risk to human health. However, levels of PAHs in traditionally smoked fish may pose and elevated of risk of cancer if consumed at high rates over a life time. Accurately estimating PAH exposure in cases where aquatic foods become contaminated is often hindered by sample availability. To overcome this challenge, we developed a novel analytical approach to predict PAH loads in resident crustacean tissues based on passive sampling device (PSD) PAH measurements and partial least squares regression. PSDs and crayfish collected from 9 sites within, and outside of, the Portland Harbor Superfund site captured a wide range of PAH concentrations in a matrix specific manner. Partial least squares regression of crayfish PAH concentrations on freely dissolved PAH concentrations measured by PSDs lead to predictions that generally differed by less than 12 parts per billion from measured values. Additionally, most predictions (> 90%) were within 3-fold of measured values, while state of the art bioaccumulation factor approaches typically differ by 5 to 15-fold compared to measured values. In order to accurately characterize chemical exposure, new analytical approaches are needed that can simulate chemical changes in bioavailable PAH mixtures resulting from natural and/or remediation processes. An approach based on environmental passive sampling and in-laboratory UVB irradiation was developed to meet this need. Standard PAH mixtures prepared in-lab and passive sampling device extracts collected from PAH contaminated environments were used as model test solutions. UV irradiation of solutions reduced PAH levels 20 to 100% and lead to the formation of several toxic oxygenated-PAHs that have been previously measured in the environment. Site specific differences in oxygenated-PAH formation were also observed. The research presented in this dissertation can be used to advance chemical exposure estimation techniques, rapidly and cost-effectively quantify a suite of PAHs in biotic tissues, and simulate the effect of abiotic transformation processes on the bioavailable fraction of environmental contaminants. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from April 3, 2013 - April 3, 2014