On a conference call with reporters, EPA Administrator Lisa Jackson announced that the EPA would take steps to “significantly scale back” the use of dispersants, the toxic chemicals being used to break up oil at or below the surface. “We believe we can ramp down the overall use of dispersants because the sub-sea use appears to be having a positive effect… I think we can reduce them by as much as half or I believe 75%,” Jackson said. Rear Admiral Mary Landry has been monitoring dispersant use in recent days and believes that BP has been reducing their usage.

However, BP continues to use Corexit, the same dispersant deemed too toxic to continue to use in the Gulf of Mexico. In response to BP blowing off the 72-hour window to come up with an alternative product, instead defending their use of Corexit, EPA Administrator Jackson announced herself “not satisfied” with BP’s justification for using Corexit, saying that “they seemed more interested in defending their official decisions than exploring other options.” But rather than ban Corexit, EPA will now perform their own scientific experiments on dispersants, aimed at finding the least toxic option.

It’s a bit jarring that EPA doesn’t have data on dispersants at the ready before now, but Rear Admiral Landry explained that nobody anticipated the chemical product would ever need to be used in this scale and scope, even when she authorized pre-approval of their use.

Dispersants have been found to cause illnesses in fishermen, particularly lung damage and potential brain lesions. This is why, according to Jackson, they would rather use sub-sea dispersants in smaller numbers than large amounts on the shore. Jackson believes they have the authority to stop all dispersant use whenever they deem it necessary, but they aren’t doing it at this time. Landry added that sub-sea dispersant use was needed to prevent flammable gas coming to the surface of the water, and impede emergency operations.

Jackson disputed the view that EPA made an order to switch dispersants last week, saying that she doubted BP’s ability to come up with an alternative without approval. “We’re not satisfied that BP has done an extensive enough analysis of dispersant options.”

Calling the disaster “one of the greatest environmental challenges of our time,” Jackson stressed that the first priority was to stop the flow of oil at the bottom of the Gulf. BP has delayed their latest option on that, the “top kill” approach to shut down the well.

See also Marcy Wheeler on a potential alternative to Corexit.