The chemical being used in the Gulf of Mexico to help disperse the onslaught of oil is no more toxic than oil itself, according to a preliminary government study.

The Environmental Protection Agency (EPA) released peer reviewed results from the first round of its own independent toxicity testing on eight oil dispersants last week, including Corexit, the dispersant BP is currently using in the Gulf. The agency found all eight to be within the range of “practically non-toxic” to “slightly toxic.”

Approximately 1.69 million gallons of Corexit has been used–applied both subsea and at the surface. The chemical breaks up the oil, making it easier for microbes to further break it down, but many questions remain about the chemical’s toxicity in the food chain and the long term effect to the environment.
  
EPA’s results indicated that none of the eight dispersants tested, including Corexit, displayed biologically significant endocrine disrupting activity. Scientists focused on dispersant toxicity for small fish and mysid shrimp. Corexit proved to be slightly less toxic than oil for small fish. 

“While this is important information to have, additional testing is needed to further inform the use of dispersants,” said the agency in a statement, which noted that the agency has yet to conduct similar tests looking at the impacts of dispersant when mixed with oil.

Though more data is needed, EPA officials continue to emphasize the important role the dispersant plays in responding to the ongoing oil leak.

“The decision EPA and the Coast Guard made to authorize the use of dispersants was a difficult choice, but one suited to the emergency that we are facing,” said Dr. Anastas, EPA’s assistant administrator for the Office of Research and Development, on a recent call with reporters. “With a spill of this size and scope, dispersants are useful in breaking up the oil and preventing its spread — particularly to fragile wetlands.”

According to the agency, the next phase of testing will look at acute toxicity of dispersants when mixed with Louisiana Sweet Crude oil. The results from the second phase will likely be more telling, as most, if not all, of the dipsersant curretly in the Gulf is intermixed with oil.  The agency also announced last week it is conducting additional studies to better understand endocrine activity.