Those who’ve followed the Gulf spill coverage know that early on in the BP disaster, before there was any real public discussion of the potential health and environmental trade-offs, BP began spraying dispersants in the Gulf with the knowledge and approval of the EPA and the Coast Guard.

How exactly those dispersants came to be approved was the subject of a hearing today before a Senate Environment and Public Works subcommittee.

As we’ve reported, the EPA already had a list of authorized dispersants on the National Contingency Plan Product Schedule. To get on that list, manufacturers must submit information on a dispersant’s effectiveness and toxicity. Here's how we explained it earlier:

The toxicity tests are part of the listing criteria only in the sense that they must be done and the paperwork must be filed with the EPA. But there’s no maximum toxicity for products to be included on the EPA’s list.

The EPA does make clear that just because a product is on the authorized list does not mean it can automatically be applied to an oil spill—it needs additional approval. But what today’s hearing revealed is that none of those additional layers of approval compared the toxicity of different dispersants or tried to distinguish which dispersants might be preferable.

(As we now know, even though the EPA’s official position is that the dispersants are roughly equal in toxicity, a mixture of oil and dispersant can range from "slightly toxic" to "highly toxic" depending on the dispersant.)

So when the spill occurred, a team of government agencies and state officials (also known as a regional response team) "preapproved" the EPA's entire list of dispersants—once again, without evaluating the toxicity of individual dispersants. The Coast Guard’s federal on-scene coordinators then gave BP the final nod to go ahead and apply one of the products, Corexit, in the Gulf.

"There was no examination done of which might be better or worse," Sen. Sheldon Whitehouse said at the hearing. "They just took the entire list and said, ‘You’re all in.’" He added, "I can’t think of another circumstance in which a regulatory agency approves something for use without actually coming to a formal decision that it is safe to be used."

"I think that’s a really good point," said David Westerholm, head of the National Oceanic and Atmospheric Administration’s Office of Response and Restoration. "They didn’t preselect any given dispersant. Once it made the list, they had to treat that list as a collective."

The EPA concurred.

"Senator, you’re making an extremely important point," said Paul Anastas, a top scientist at the EPA. Anastas said his agency was working on reforming the approval process for products on its authorized list.

Representatives of the EPA and NOAA also spoke on bioaccumulation, downplaying fears that the chemicals in dispersants would accumulate in aquatic life and that toxicity would be magnified higher up in the Gulf food chain. They acknowledged, however, that this, too, should have been considered beforehand.

"We should have a series of tests to more definitively prove that" dispersants don’t bioaccumulate, and then use that as part of the listing criteria for the contingency plan, Westerholm said.

Both NOAA and the EPA have put out rosy reports this week about activity in the Gulf.

NOAA reported today that the "vast majority of the oil from the BP oil spill has either evaporated or been burned, skimmed, recovered from the wellhead or dispersed using chemicals."

The EPA announced this week that because most of the dispersant-oil mixtures it tested were around the same toxicity as the oil alone—or "moderately toxic"—the choice to use them, overall, had been effective, and "a wise decision." It also said that oxygen levels in the Gulf, though low, had not fallen below levels of concern.

On those oxygen levels, the Houston Chronicle reported Tuesday that scientists measuring the "dead zone" off the coast of Texas say that this year, the low-oxygen area is larger than they have ever measured.

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