With increasing oil exploration and ship traffic in the U.S. Arctic, there is concern about the increased potential for an oil spill event in this region of the world. Baseline exposure levels of oil-spill related contaminants are lacking for marine mammals, particularly endangered or threatened populations (e.g., ice seals, bowhead whales). Identification of the appropriate tissues/fluids to assess recent exposure of marine mammals to oil components must be determined, as well as the type of oil spill-related contaminant (e.g., parent polycyclic aromatic hydrocarbons (PAHs), metabolites of PAHs). To help address these data gaps, various matrices of Arctic marine mammals will be collected during subsistence harvests and from fresh dead stranded animals over the next year and these samples will be analyzed for oil-spill related compounds. These tissues will also be analyzed for additional oil-spill related components after the methods have been developed and validated. Under the guidance of NOAA Fisheries Office of Protected Resources, we will collaborate with the National Institute of Standards and Technology to develop and test appropriate standard reference materials and control materials for these analyses to ensure that the chemical contaminant data generated for this project are of known and acceptable quality. Concentrations of PAHs and alkylated PAHs in Arctic marine mammal tissues.