Abstract

On April 20, 2010, an explosion on the Deepwater Horizon oil rig led to the deaths of 11 workers and the release of over 206 million gallons of crude oil over the course of 87 days. The resulting size of this spill was estimated to cover as much as 28,959 square miles. In response to this oil disaster, relief efforts focused on eliminating the oil as quickly as possible. The primary relief response was the application of over 1.8 million gallons of chemical dispersants sprayed on the ocean surface and injected near the well head. There has been a lot of concern for the Gulf of Mexico ecosystem following this disaster, largely focused on the impacts of the oil and dispersants while the threat of genotoxic metals in the oil has gone largely overlooked. Genotoxic metals, such as chromium and nickel, break DNA and can accumulate in tissues of exposed organisms resulting in longer exposures. We collected skin biopsies from free ranging sperm whales in the Gulf of Mexico during the summers of 2010 (immediately after the spill), 2011 and 2012, many of which were encountered in areas where the oil slick occurred. We found chromium and nickel levels ranged from 0.24–8.46 ppm in crude oil from oil slicks, tar balls from Gulf beaches, and oil from the Deepwater Horizon riser. Samples collected from 2010 in the months following the well head being capped showed chromium and nickel levels ranging from 0.4–94.63 ppm. Mean levels of chromium and nickel in Gulf of Mexico sperm whales were significantly higher than the global average from sperm whales collected prior to the spill. Given the known toxicity of these metals in vertebrates, their presence in the oil, and their elevated levels in the whales, we believe metal exposure is an important overlooked concern for the Deepwater Horizon oil disaster.

Acknowledgements

This work was supported by the University of Southern Maine, the Maine Center for Toxicology and Environmental Health. Ocean Alliance, The Albemarle Corporation, the Campbell Foundation, the Ocean Foundation, Quiznos, NIEHS grant ES016893 J. Wise Sr., PI), ARO grant # W911NF-09-1-0296 (J. Wise Sr., PI) and the many individual and anonymous Ocean Alliance and Wise Laboratory donors.

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