Reporting from Atlanta — The Environmental Protection Agency issued a study Wednesday that found that the dispersant being used by BP in the Gulf of Mexico, as well as seven alternative mass-produced dispersants, all fell within the range of "practically non-toxic" to "slightly toxic."
The conclusions, although preliminary, appear to support BP's contention that there is little difference between Corexit 9500 and other dispersants available on the market, an argument the oil giant used in rebuffing EPA's order in May to stop using the chemical.
But the study offered little relief to environmentalists and ocean scientists concerned about the unprecedented amounts of dispersant being sprayed into the gulf in an attempt to mitigate BP's massive oil leak. Equally important, they say, are studies that would measure the toxicity of the Louisiana sweet crude as it mixes with the dispersants.
In a conference call with reporters, Paul Anastas, EPA's assistant administrator for research and development, said the agency was working on such a study. Before making any alterations to its current policy, he said, "we will need to have this additional testing of the dispersants plus the oil."
Dispersants bond to oil molecules and separate them from water molecules, somewhat similar to the way dish soap pulls apart oil and water in a kitchen sink, according to Nalco, Corexit's Illinois-based manufacturer. The dispersed oil then can be broken down more easily by microorganisms in the ocean.
On May 20, the EPA ordered BP to stop spraying Corexit 9500 in the water and find a less-toxic alternative. But the oil company refused, saying the product continued to be "the best product for subsea application." To date, the company has sprayed 1.6 million gallons of dispersant on the ocean's surface and at the site of the blown-out well a mile underwater.
The study released Wednesday measured the effect of Corexit 9500 and seven other dispersants on two Gulf of Mexico species, the mysid shrimp and the tiny inland silverside fish. The results, the agency stated, "indicated that none of the eight dispersants tested, including the product in use in the gulf, displayed biologically significant endocrine disrupting activity."
Disruption of the endocrine system, a sensitive set of regulating glands and hormones, can lead to reproductive problems for numerous species.
Richard Charter, a senior policy advisor for marine programs for the nonprofit group Defenders of Wildlife, said the results of EPA's studies were "inconclusive." He said the federal government needed to investigate whether the use of dispersants has helped form the subsea masses of oil detected by government and academic researchers. Charter and others fear that the oil, when pushed underwater, cannot be defended by the miles of boom laid out to catch oil floating on the surface.
"A fundamental question is…did the behavior of the oil through the use of dispersants make things more complicated at the shoreline response end?"
Other scientists worry about the effect of the oil-dispersant mix on sea life below the surface, including tiny plankton and large marine mammals.
Lisa Suatoni, a senior scientist with the Natural Resources Defense Council, said the "really interesting questions" would be answered after EPA looks at the toxicity of the oil-dispersant mix. But she was concerned that the agency will test its effects only on the same shrimp and fish, hardly representative of the staggering biodiversity in the Gulf of Mexico.
The report was released on a day when another key aspect of the spill response — the use of skimmer boats — was stymied by big swells kicked eastward by Hurricane Alex, which was expected to strengthen from a Category 1 to a Category 2 hurricane Wednesday before spinning into the northeast coast of Mexico, according to meteorologists at AccuWeather.com.
U.S. Coast Guard Petty Officer Kelly Parker said all near-shore skimmers in Louisiana were sent to port because of the high waves, and were expected to take back to the water Friday. A spokeswoman for the response effort in Mississippi, Alabama and Florida said no skimming had been performed in those states.
In Washington, top Obama administration officials, including Interior Secretary Ken Salazar, Coast Guard Adm. Thad Allen and Energy Secretary Steven Chu met with BP officials Wednesday afternoon at the Interior Department to discuss whether they should remove the containment cap atop the broken well and replace it with a better-fitting one.