TP4 Toxicity of Complex Mixtures
204 Oregon Ballroom
1:20 PM - 4:40 PM, Tuesday
() EROD activity (CYP1A) inducing compounds in fractionated crude oil.
Khan, C1, Hollebone, B2, Wang, Z2, Ramachandran, S1, Clarke, L1, Hodson, P1, 1 Queen's University, Kingston, Ontario, Canada2 Environment Canada, Ottawa, Ontario, Canada
ABSTRACT- CYP1A induction, as measured by the EROD assay, is an effective biomarker of polycyclic aromatic hydrocarbon (PAH) uptake by fish. Crude oil is a major source of PAH in the aquatic environment. PAH are known to cause developmental malformations in the early life stages of fish and we have observed similar effects in larval fish exposed to crude oil in the laboratory. Due to the complex chemical make-up of crude oil, it is uncertain as to which constituents cause toxicity. This research is part of a Toxicity Identification and Evaluation (TIE) of different crude oils, to test the hypothesis that the toxicity of crude oil is due primarily to the PAH. Preliminary experiments compared the amount of bioavailable PAH among different crude oils, and illustrated whether chemical fractionation of these oils separated PAH and toxicity in the same fractions. Bioavailable PAH were measured by the extent of CYP1A induction in rainbow trout exposed to oil in water over 48 hours. Fractions of each oil were created by low temperature distillation, corresponding roughly to white gas, kerosene, coal tar/bitumen, and wax. Preliminary results show that whole oil induced hepatic EROD activity with an increase in exposure concentration. We found that the coal tar/bitumen fraction, the highest in PAH, accounted for most of the CYP1A induction in the whole oil. Trout exposed to the wax fraction of crude oil also exhibited moderate CYP1A induction. It is expected that further distillation of the coal tar/bitumen fraction will reveal alkylated phenanthrenes as the most potent CYP1A inducers. Following further fractionation, it is also expected that benzo(a)pyrene will account for all CYP1A induction in trout exposed to wax.
Key words: erod, cyp1a, oil, induction