Risk assessment of human chemical exposure entails calculating the risk levels of exposure to individual chemical compounds at different sites of release, and is usually carried out for different exposure pathways specific to the site and scenario of the chemical release. The types of scenarios specific to environmental assessment are leaks from above-ground and underground fuel storage tank farms, and spills occurring during transportation of the fuel. If human exposure is solely considered as part of the risk assessment process, cancer risk levels and non-cancer risk levels are calculated. Essentially, environmental risk assessment process includes four main steps: Hazard Identification, Dose-Response Assessment, Exposure Assessment, and Risk Characterization. These steps are more challenging to carry out for fuels as fuels are muticomponent mixtures of unknown compounds. Therefore, a risk assessment methodology involving fractions of the fuels must be devised. One such methodology for petroleum-based fuels is known as the total petroleum hydrocarbon criteria working group (TPHCWG) methodology. One key aspect of this project is to test whether the TPHCWG methodology is relevant to aviation biofuels.