British Petroleum officials say that its latest attempt to stop the flood of oil gushing into the Gulf of Mexico is working, amid new questions about the safety of the chemicals used to break up the oil already in the environment.
With the "top kill" attempt well underway, Coast Guard Admiral Thad Allen seconded BP's take, saying that the gushing oil from the well has at least temporarily stopped, although some pressure from the well remains.
The top kill method, which relies on pumping thousands of gallons of heavy mud into the well shaft in order to stanch the flow of oil, was widely seen as a last-ditch effort to contain what is now officially the largest oil spill in U.S. history.
While hopes run high for stopping the flow of any additional oil into the Gulf, significant challenges remain for cleaning up the 17 million to 39 million gallons that have already polluted the ocean and the coasts of Louisiana, Alabama and Florida to date.
BP has relied on massive quantities of two types of an oil dispersant called Corexit to break up the oil into what it calls more easily broken-down portions. The chemicals, Corexit 9527A and Corexit 9500, are known to be hazardous to aquatic life and to humans.
Corexit 9527A is the older product, and considered more toxic. According to its Material Safety Data Sheet [PDF], it contains a chemical called 2-butoxyethanol -- at a level of between 30 percent and 60 percent by weight (the public information on these products is maddeningly inexact). Since writing the post last week, I've come upon the entry for 2-butoxyethanol on the website of Haz-Map, a service of the National Library of Medicine that provides "information about the health effects of exposure to chemicals."
This is not charming stuff, according to Haz-Map:The EPA has since gone on to say that the use of Corexit 9527 has since been discontinued, because the existing supply has all been used in the Gulf.
Severe hemoglobinuria and changes in the lungs, kidneys, and liver are seen in mice after 7-hour lethal concentration studies. Volunteers showed no evidence of adverse effects other than mucous membrane irritation after 8 hour exposures to 200 ppm. ... For ethylene glycol ethers, there is limited positive evidence of spontaneous abortions and decreased sperm counts in humans and strong positive evidence of birth defects and testicular damage in animals.
Today, Nalco released a statement affirming the safety of Corexit. The statement reads in part:
COREXIT 9500, the only dispersant Nalco is manufacturing to help break up the oil spilling into the Gulf of Mexico, is a simple blend of six well-established, safe ingredients that biodegrade, do not bioaccumulate and are commonly found in popular household products, the company said today. The COREXIT products do not contain carcinogens or reproductive toxins. All the ingredients have been extensively studied for many years and have been determined safe and effective by the EPA.
The release goes on to compare the chemicals to chemicals in household products, including:
• One ingredient is used as a wetting agent in dry gelatin, beverage mixtures, and fruit juice drinks.
• A second ingredient is used in a brand-name dry skin cream and also in a body shampoo.
A third ingredient is found in a popular brand of baby bath liquid.
I spoke with Richard Denison, a senior scientist at the Environmental Defense Fund, about the chemicals, and particularly about Nalco's disclosure today.
"It raises as many questions as it answers," Denison said. "The assurances that these are in common household products is not much of an assurance," he added, because there's not much testing required of chemicals used in household products."
With regards to Corexit in particular, Denison said that even though it has been tested -- though not nearly to the extent that would vindicate its safety, or even to the extent that Nalco implies in its statement today -- those tests are not necessarily applicable to how humans and wildlife are encountering the chemical.
"The biggest problem is that the vast majority of testing done on these chemicals is that when it is done, it is at best limited to very short-term, acute toxicity tests," Denison said. "The concern here is not [short-term exposure] nearly as much as longer-term chronic toxicity. The dispersants are going to get diluted, spread out over a large area, and effects they're likely to exert would be due to relatively long exposrues over a long period of time."
But over the course of the last week, BP and the EPA have been engaged in a slow-motion showdown over Corexit and less toxic alternatives. After calling on BP to use a different, less toxic dispersant, BP essentially declined, saying that there weren't other dispersants on the market that meet the triple demands of effectiveness, safety and availability.
The government conceded the battle this week, saying that despite concerns about its safety, none of the other 18 dispersants cleared for use in the U.S. were available in the needed quantity.
Which is not to say that there aren't more effective and less toxic than Corexit: The EPA has found that "Corexit ranks far above dispersants made by competitors in toxicity and far below them in effectiveness in handling southern Louisiana crude."
For now, the only good news is that the top kill process seems to have had some success, although it could be another day or two before BP or the EPA can say for sure that it's stopped the flow of oil.
But even if the well gets plugged, there still remains an enormous cleanup process, one sure to cost billions of dollars and last for years or decades. And without knowing exactly what chemicals have been used to disperse the oil that has already spilled, the environmental impacts may never be known.
Denison said there's only one solution for that particular quandary: Nalco should release a full ingredient list for Corexit, as well as disclose any material testing data it has.
"In our view, there needs to be the ability, given the scale and the magnitude of the use here for independent testing of the risks of the material at use here," Denison said. "It's not sufficient to rely on the word of the producer of the dispersant as to its risks."