Oil dispersant does not pose environmental threat, early EPA findings suggest

By Juliet Eilperin
Wednesday, June 30, 2010; 9:01 PM

The Environmental Protection Agency released its first round of testing results on the toxicity of oil dispersants Wednesday, saying initial findings suggest that the dispersant BP is using in the Gulf of Mexico is less harmful than oil and does not pose as significant an environmental threat as the spill does.

In a telephone news conference, EPA's assistant administrator for research and development, Paul Anastas, emphasized that it was "too early to draw conclusions" about the long-term impact of Corexit 9500, the dispersant BP has applied to break up oil spewing from the downed Deepwater Horizon rig. The agency has yet to analyze the impact of dispersants mixed with oil and instead just tested the application of eight types of dispersants to marine animals in a lab setting.

"We need more data to decide whether it's necessary to switch dispersants," Anastas said, adding: "All of the dispersants are roughly equal in toxicity, and all of them are less toxic than oil. . . . It's important to remember that oil is enemy number one in this crisis."

But environmentalists questioned the kind of testing EPA conducted, noting that its scientists applied the chemical compounds to mature marine life and then examined the impact either 48 or 96 hours later, instead of observing what would happen after repeated applications.

Alaska-based activist Riki Ott noted that "fresh oil and fresh dispersant are being released constantly" in the gulf, so the lab results could not capture that sort of repeated exposure. "Right off the bat it's more toxic than a standard, static test," Ott said, adding that EPA officials did not test the impacts on "young life forms" such as juveniles and larvae, which are more vulnerable to toxic chemicals.

Richard Denison, a senior scientist at the Environmental Defense Fund, wrote in a blog post that the lab results did not shed new light on dispersants' impact, in part because they were tested in isolation.

"So, what did we learn today? Not too much new," he wrote, adding, "What is most remarkable about the data EPA released today is how similar they are to the industry-supplied data on the dispersants by themselves that were previously made available on EPA's Web site."

Researchers tested the dispersants on mysid shrimp and inland silverside fish. None of the dispersants appeared to disrupt the animals' endocrine activity, according to the results, and EPA issued a statement saying it found "JD-2000 and Corexit 9500 were generally less toxic to small fish and JD-2000 and SAF-RON GOLD were least toxic to mysid shrimp."

In late May, EPA directed BP to find another, less toxic dispersant than Corexit 9500, but the company refused to do so, arguing that it could not find an adequate substitute in sufficient quantities. Both EPA and the Coast Guard instructed BP to reduce its use of dispersants by 75 percent, and the company has cut its application of Corexit 9500 by 68 percent from its peak over the past month.

EPA will embark on a second round of testing to evaluate the toxicity of different concentrations of Louisiana Sweet Crude Oil alone and combinations of the oil with each of the eight dispersants.

"It's crucial that we get this other data on the dispersant with the oil," Anastas said, adding that the agency also needs to examine issues such as why it has no maximum toxicity threshold for products that make it onto the federal government's list of accepted dispersants. "This tragedy, this event, at the scope and the scale of this event, has raised important questions about how these previously existing regulations need to be reexamined."

He added that while questions have been raised about whether the dispersants are settling on the sea floor or remaining suspended in the water, testing suggested that they break down "within weeks" when used on the surface and "within weeks or months" when applied to the colder waters below.

"We are seeing no data that there are dispersants that are persisting in the water column," he said.

Still, Ott questioned why the federal government was allowing such widespread use of chemicals in the ocean.

"What we need to do in an oil spill situation is do no more harm," she said. "Putting toxic solvents on top of an already toxic substance is doing more harm."

An EPA spokesman, Brendan Gilfillan, said, "The tests conducted by EPA -- which involved two species which are native to the gulf -- were based on standard scientific acute toxicity test protocols."

© 2010 The Washington Post Company