Corexit Makes Oil Spills Worse, Not Better, Scientists Find

By Kiley Kroh, crossposted from ThinkProgress Green.  In yet another alarming glimpse at the long-term effects of the BP disaster, the preliminary findings of two new studies show that the nearly two million gallons of toxic dispersants applied to the more than 200 million gallons of oil that gushed from its exploded rig may have been more damaging to the ecosystem as a whole than the oil alone.

The government approved application of the dispersants in an attempt to prevent oil and tar mats from washing into the marshes along the coast. BP maintained the dispersants would break down the oil and allow more of it to be eaten by bacteria that would consume some of the most harmful products in the oil -– “just like dish soap on grease.” But initial experiments conducted by Wade Jeffrey, a biologist with the University of West Florida’s Center for Environmental Diagnostics and Bioremediation, point to the opposite. After adding BP oil to seawater and combining with Corexit, Jeffrey found that the chemicals did not have their intended effect:

"The way we’re doing the experiment, the Corexit does not seem to facilitate the degradation of the oil."

In fact, Jeffrey found that the combination of Corexit and oil was more toxic to phytoplankton in the sample than oil alone and did not prompt the oil-eating bacteria to consume the oil any faster.

A similar study, conducted by Susan Laramore of Florida Atlantic University’s Harbor Branch Oceanographic Institute and also released last week, looked at the effects of the oil-Corexit mixture on slightly larger species, including conch, oysters and shrimp. Early results point to the same conclusion – that the oil and dispersant mixture is more toxic than the oil alone. Laramore notes that her study runs directly counter to the assurances BP and others presented to the public when making the case for dispersant use:

"These results are backwards of what the oil companies are reporting."

In the immediate aftermath of the spill, BP quickly stockpiled and deployed massive quantities of Corexit with the aim of keeping the oil from fragile marshlands – and out of the public eye. As E&E News uncovered, the chemical is manufactured by “a company that was once part of Exxon Mobil Corp. and whose current leadership includes executives at both BP and Exxon.” According to EPA data, “Corexit ranks far above dispersants made by competitors in toxicity and far below them in effectiveness in handling southern Louisiana crude.”

The oil giant simultaneously worked to convince an uneasy public that the chemicals, previously untested at such depths, would naturally biodegrade. In an official statement last year, BP called the chemical “one of the most well-studied dispersants” and asserted that it would rapidly biodegrade, in many cases in a matter of days. Even when it became clear the company was using the chemicals in “unprecedented volumes” and the EPA demanded BP find a less toxic alternative, the oil giant refused to comply, calling Corexit “the best option for subsea application.”

Both the Jeffrey and Laramore studies, however, clearly debunk BP’s claims that the materials would prove benign. Frustrated by the lack of federal response to their requests for a less-toxic alternative and no longer willing to subject its coasts and citizens to the harmful chemicals, the state of Louisiana has taken matters into its own hands – the senate is moving forward this week with a bill that would effectively ban the use of dispersants in responding to oil spills in Louisiana waters.

Kiley Kroh is the Associate Director for Ocean Communications at the Center for American Progress.