How toxic is oil? Investigating specific receptor-mediated toxic effects of crude and refined oils

Crude oils and refined oil products are major pollutants of the environment. Large oil spills, such as the recent blowout of the Deepwater Horizon in the Gulf of Mexico, raise concerns about the long term health effects of petroleum hydrocarbon exposure on wildlife and humans. In the environmental risk assessment of oils, narcosis (the disruption of an organism’s membrane structure) is the only mode of action assumed to determine the toxicity of petroleum hydrocarbons. However, several crude oils, refined products, offshore drilling produced waters, and oil-sands process affected water display endocrine disruptive properties in both in vitro and in vivo systems. Unfortunately, the available information is fragmentary in the sense that only a few oil types have been tested in only one type of in vitro assay at a single time point, the causative compounds have not been identified, and the bioaccumulation potential of the in vitro active chemicals has not been determined. Therefore, the aims of the research presented in this thesis were to identify the possible endocrine disruptive properties of different, environmentally-relevant crude oils and refined oil products in a battery of in vitro bioassays, identify the chemical classes responsible for the observed effects, and link the in vitro-observed effects to the hydrophobicity (and thus the bioaccumulation potential) of these chemical classes.