Investigating the Mutagenicity of Polycyclic Aromatic Compounds from the Athabasca Oil Sands Region in River Otters and a Mammalian Cell Line

Abstract

Mining operations have led to an increase in polycyclic aromatic compound (PAC) concentrations in the Alberta oil sands area. However, the toxicity of most PACs and PAC mixtures is not well characterized. Some PACs and PAC mixtures are known to be mutagenic, though there is limited research on the genotoxicity of PACs from the Alberta oil sands to wildlife. This thesis tested the hypothesis that anthropogenic sources of PACs from the Alberta oil sands are mutagenic to wildlife. The objectives were: 1) to determine whether wildlife with increased exposure to PACs had increased mutations, and 2) to determine whether an anthropogenic source of PACs is mutagenic in a controlled lab setting. For the first objective, we used a single-molecule polymerase chain reaction (SM-PCR) assay to detect microsatellite mutations in river otters with differing liver tissue PAC concentrations in the Athabasca oil sand region (AOSR; Alberta, Canada). For objective two, an in vitro mammalian mutagenicity assay with the FE1 MutaMouse epithelial cell line (FE1) was used to determine the mutagenic potential of a bitumen extraction by-product, tailings pond bitumen. We found that PAC exposure in the AOSR was positively correlated with elevated microsatellite mutations in river otters. From the in vitro study, tailings pond bitumen extracts did not induce lacZ mutations in the FE1 cells. Differences in detection methods between the two assays and PAC profiles between the otter tissue and tailings pond bitumen are suspected reasons for contradictory results. Further investigation of the different sources and PAC profiles within the AOSR environment and wildlife food web will provide insights on what types of PACs are mutagenic. Cytotoxicity, observed following exposure to tailings pond bitumen extracts, also suggests other toxicity pathways should be considered when investigating the toxicity of bitumen from the AOSR. Overall, this thesis provided data on the potential mutagenicity of PACs in the AOSR, which can be used to elucidate potential molecular mechanisms of toxicity in wildlife exposed to oil processing contaminants.