Abstract

On April 20th, 2010, the Deepwater Horizon Oil Rig exploded in the Gulf of Mexico, causing 200 million gallons of oil to gush into the ocean. Efforts to contain the oil included applying nearly 2 million gallons of chemical dispersants to break it up. However, the toxicity of these dispersants is unknown. The objective of this study is to determine the toxicity of the two dispersants (Corexit® EC9500A and EC9527A) used in the Gulf on sperm whales. EC9527A was also used in small amounts in Alaska and was shown to be ineffective in the amounts used. Specifically, we determined the cytotoxicity of dispersants in sperm whale skin cells. 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. Further studies currently in progress are considering oil and dispersed oil 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).