EROD activity (CYP1A) inducing compounds in fractionated crude oil

This study tested the hypothesis that toxicity of crude oil is caused, in large part, by polycyclic aromatic hydrocarbons (PAH). Crude oil is a major source of PAH in aquatic ecosystems. Although it is known that PAHs cause developmental deformations in the early life stages of fish and larvae, it is not known which constituents of oil cause toxicity. Cytochrome CYP1A induction as measured by ethoxyresorufin-O-deethylase (EROD) activity, is an effective biomarker of PAH uptake in fish. This study compared the amount of bioavailable PAH among different crude oils to determine if chemical fractionation of the oils separates PAH and toxicity in the same fraction. Bioavailable PAH was determined by the extent of CYP1A induction in rainbow trout exposed to hydrocarbon-polluted water over a 48 hour period. The results showed that the whole oil induced hepatic EROD activity with an increase in exposure concentration. The coal tar/bitumen fraction probably accounted for all the observed CYP1A induction in the oil. 15 refs., 5 tabs., 2 figs