Scientists told a Senate panel today that the chemical dispersants BP poured into the Gulf of Mexico to dilute the oil from its ruptured well seem to have disappeared.
But scientists add that out-of-sight doesn't mean out-of-mind, and they point out that the long-term effects of these chemicals remain a mystery. BP put almost 2 million gallons of dispersants into the Gulf.
Republican Sen. John Barrasso of Wyoming said the circumstances made for a tough choice. "They leave responders with a Catch-22 -- either you're blamed for dumping chemicals in the Gulf or you allow the oil to devastate the Gulf."
Barrasso spoke at a hearing by a panel of the Senate Committee on Environment and Public Works, which is weighing new legislation to regulate the use of chemical dispersants.
Those dispersants -- BP used two kinds of a chemical called Corexit -- are toxic and government scientists say cleanup workers were warned and took safety precautions. As for the dangers of wildlife exposed to it? Nobody really knows.
"What we do know right now is this: we aren't seeing dispersants in our monitoring results," said Paul Anastas, a chemist at the Environmental Protection Agency. The EPA has looked in deep water, as well as along the Gulf coastline -- and no dispersants showed up.
But scientists who study marine life point out that the lack of dispersants in tests doesn't mean the chemicals haven't affected marine life in the gulf. Among those scientists is toxicologist Ronald Kendall at Texas Tech University, who implored the senators not to think that the worst is over.
"This is uncharted territory," he said. "We need science now."
Kendall said what's happening in the Gulf right now is a huge, uncontrolled experiment. "Did we really understand the environmental toxicology of such a massive use in the deep water of a substance such as Corexit? And I say, we did not."
Tests by EPA performed since the spill show that the Corexit dispersant is slightly less toxic than the oil itself. When it mixes with the oil, the combination is no more toxic than oil itself. And by now, Corexit is highly diluted in a vast body of water.
But "toxic" is a hard thing to pin down. Tests done before and after the spill looked at short-term effects of dispersants on only a few species of fish and shrimp. Many of those were done by the manufacturer, not by government regulators.
The EPA's Anastas acknowledged that science's work is just beginning.
"I am not suggesting that we have perfect knowledge. I am not suggesting that we don't need more information and more monitoring," he said. "I am actually saying straight out that it is important to keep on asking these hard questions."
A lot of marine scientists are asking those questions and wondering where the money will come from to answer them, especially once the drama in the Gulf goes the way of the oil slicks.
"We cannot just sweep this under the rug and say 'OK, we're collecting all the oil and it's going away. We don't have that much to worry about any more,'" says Dana Wetzel, a chemist who's spent years studying dispersants at the Mote Marine Laboratory in Florida. "I contend that that's so absolutely wrong."
A lot of oil wasn't collected or burned off and could remain under the Gulf in great clouds of oil and dispersant. Wetzel says the potential long term effects of this chemical cocktail on everything from coral reefs to whale sharks are unknown.
"Will they reproduce as they normally would?" she asked. "Will they have the same number of offspring? It doesn't end there. Will those offspring reproduce? Is their immune system compromised?"
The government and BP are hiring scientists to figure these things out, but because their findings may figure in lawsuits against BP, not all the results may be made public. [Copyright 2010 National Public Radio]