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Aug 2, 2010 2:55 PM by Melissa Canone

Dispersant is Less Toxic Than Oil Alone

WASHINGTON (AP) - A new federal study of chemical dispersants
used to break up oil in the Gulf of Mexico shows that when mixed
with oil, the dispersant is less toxic to aquatic life than oil
alone.
The study also show that when mixed with oil, the dispersant
used in the Gulf, Corexit 9500A, is no more or less toxic than oil
mixtures with other chemical dispersants approved for use in oil
spills.
The Environmental Protection Agency released the study results
Monday as the Obama administration defended itself against
assertions that officials allowed oil giant BP to use excessive
amounts of chemical dispersants whose threat to sea life remains
unknown.
Congressional investigators charge that the Coast Guard
routinely approved BP requests to use thousands of gallons per day
of Corexit despite a federal directive to use the chemical
sparingly.
The Coast Guard approved 74 waivers over a 48-day period after
the Environmental Protection Agency order, according to documents
reviewed by the investigators. Only in a small number of cases did
the government scale back BP's request.
EPA Administrator Lisa Jackson said in a statement that
officials have long acknowledged use of dispersants presents
environmental trade-offs. The agency took steps to ensure that
other response efforts were used instead of dispersants and
dramatically cut dispersant use in late May, she said.
Dispersants were last used July 19, four days after a temporary
cap was placed on the leaking Macondo well, and dispersant use
dropped by 72 percent from peak volumes following a joint EPA-U.S.
Coast Guard directive to BP in late May, Jackson said.
Paul Anastas, EPA assistant administrator for research and
development, said he was surprised to learn that the mixture of
dispersant and oil was about the same toxicity as the oil alone.
That result shows that use of the dispersant "seems to be a
wise decision, and that the oil itself is the hazard that we're
concerned about," Anastas said. He called the oil that spewed into
the Gulf for nearly three months "Enemy No. 1."
While the chemical dispersant was effective at breaking up the
oil into small droplets so that it could be more easily consumed by
bacteria, the long-term effects to aquatic life are unknown. That
environmental uncertainty has led to several spats between BP and
the government over the use of dispersants on the water's surface
and deep underwater when oil was spewing out of the well.
Rep. Edward Markey, D-Mass., said more than 1.8 million gallons
of toxic dispersants were used to break up the oil as it came out
of the well and after it reached the ocean surface.

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