If BP had followed the Environmental Protection Agency directive to switch to a less toxic dispersant, the company should've already been applying a different dispersant to the Gulf oil spill by now. Instead, over the weekend, BP told the EPA that it was going to continue to use Corexit, which, as we've noted, failed key toxicity tests and was banned in the U.K. for use on oil spills more than a decade ago.

From BP's refusal letter:

"COREXIT was the only dispersant that was available immediately, in sufficiently large quantities, to be useful at the time of the spill ... Based on the information that is available today, BP continues to believe that COREXIT was the best and most appropriate choice at the time when the incident occurred, and that COREXIT remains the best option for subsea application."

The Corexit dispersants used by BP have been on the EPA's list of products previously approved for use on oil spills. But one of them, Corexit 9500A, contains a compound that is linked to headaches, vomiting and reproductive problems.

We've reached out to the EPA to ask what the agency will do about BP's refusal to comply with its directive. Where the EPA goes from here will give a window into how much authority the federal government has--and is willing to exercise--in its oversight of the cleanup, an issue on which the Obama administration continues to receive criticism.

On Sunday, Interior Secretary Ken Salazar warned BP that "if we find they're not doing what they're supposed to be doing, we'll push them out of the way appropriately."

The New York Times points out that this doesn't quite jibe with what the Coast Guard has said (or, for that matter, what White House spokesman Robert Gibbs has said) about BP's  necessarily taking the lead:

Mr. Salazar's position conflicted with one laid out several hours earlier, by the commandant of the United States Coast Guard, Adm. Thad W. Allen, who said that the oil conglomerate's access to the mile-deep well site meant that the government could not take over the lead in efforts to stop the leak.

As we reported last week, EPA officials are considering whether to bar BP from receiving government contracts, which could cost the company billions, but such a move would require investigators to find a widespread culture of noncompliance within the company.

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