Abstract

Two major oil crises in United States history, the 1989 Exxon-Valdez oil spill in Alaska and the 2010 Deepwater Horizon Oil Rig explosion in the Gulf of Mexico, drew attention to the need for toxicological experiments on oil, chemical dispersants, and chemically dispersed oil. We are still learning from effect these spills had on wildlife. However, little data is known about the toxicity of these substances in marine mammals. The objective of this study is to determine the toxicity of the two dispersants (Corexit® EC9500A and EC9527A), Alaskan and Gulf oil, as well as chemically dispersed oil. Cells were treated with and without S9 fractions with cofactors, because fibroblast cells do not readily express cytochrome p450 enzymes necessary to metabolize the chemicals. The EC9500A data show that dispersants are cytotoxic to sperm whale skin cells. Specifically, 50, 250, 500 and 1000 ppm EC9500A induced 89, 73, 46 and 7 percent relative survival, respectively. S9-mediated metabolism increased toxicity inducing 78, 60, 38 and 4 percent relative survival, respectively. The EC9527A data show that it is less cytotoxic than EC9500A. Specifically, 50, 250 and 500 ppm EC9527A induced 99, 99 and 80 percent relative survival, respectively. S9-mediated metabolism increased EC9527A toxicity induced by approximately 20 percent. Oil experiments were performed using the water accommodated fraction of oil (WAF). The Alaskan WAF does not appear to be cytotoxic to sperm whale skin cells. Chemically dispersed Alaskan oil experiments are in progress. Further studies also in progress are considering oil and dispersed oil from the Gulf of Mexico and determining the genotoxic effect of dispersants and oil in sperm whale cells.

Acknowledgements

This research is supported by The Environmental Protection Agency's Undergraduate Research Opportunities Fellowship (CFW), NIEHS grant ES016893 (JPW) and Maine Center for Toxicology and Environmental Health (JPW).

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