Alkyl PAH in crude oil cause chronic toxicity to early life stages of fish. Volume 1

In order to mitigate the risk to fisheries following an offshore oil spill, it is necessary to know the components of crude oil that are toxic. Chronic exposure of early life stages of fish to crude oil causes Blue Sac Disease, a syndrome characterized by induction of the cytochrome P450 (CYP1A) enzyme. In this study, effects-driven fractionation of Alaska North Slope Crude was used to identify the classes of compounds that cause CYP1A induction in juvenile rainbow trout and chronic toxicity to developing stages of Japanese medaka. Four fractions of compounds were created by low temperature vacuum distillation. This separated the constituents of oil according to their volatility within defined temperature ranges. The fractions were separated according to their boiling points. With a temperature range of 287-481 degrees C, fraction F3 was the only fraction as toxic as whole oil and induced CYPP1A enzymes of fish. Fractions containing specific classes of alkyl PAH were also collected. For all separations, the performance of the method was evaluated by the extent to which PAH were separated from aliphatics, resins and waxes, as well as by the quantitative recovery of mass in fractions and subfractions. The induction of CYP1A enzymes showed that PAH was present in all fractions that were highly toxic, but the toxicity tests indicated that not all fractions containing PAH were toxic. This research provided a scientific basis for comparing the risks of different crude oils based on chemical analyses that show the different proportions or amounts of PAH present. The results indicate which compounds of concern should be used to determine the extent and success of oil spill remediation, and provide a biological interpretation of chemical fingerprinting used to discriminate the sources of oil pollution. 15 refs., 1 tab