In the months since the Deepwater Horizon drilling rig exploded, and the well beneath spewed millions of gallons of crude into the Gulf of Mexico, BP has been accused of moving too slowly to clean its gigantic mess. Yet in one respect the oil giant acted swiftly. Shortly after the accident, BP began applying vast quantities of chemical dispersants in an effort to break up the torrent of oil from the mile-deep blowout. By mid-July, BP had released almost two million gallons of the dispersant Corexit.

BP and Corexit manufacturer Nalco claim that the chemicals will reduce the impact of the spill on coastal environments. Their lobbyists and executives say that the chemical is not only essential, but as harmless as dish soap.

But a fundamental question lingers like the petrochemical smell over the gulf: Is Corexit doing more harm than good? Dispersants, all agree, do not lessen the amount of oil in the environment. Rather, they break it into tiny drops that have different, but not necessarily less toxic properties.

"[Dispersants] make the oil more soluble in water, so it won't just sit on the surface," Jackie Savitz, senior scientist with Oceana told CNN. "Whether that's good or bad depends on whether you're a fish or a seabird."

But whether or not the dispersants work as promised, they are effective in other ways, critics charge. By breaking the peanut-butter thick sludge into tiny droplets, Nalco's Corexit has made the oil less visible, thereby disguising the full environmental impact of the spill, and helping BP limit its legal and financial liability. The availability of dispersants also gives the oil industry cover by allowing it to assure government agencies and the public that in the in the "unlikely" event of a spill, there is a quick, safe fix.

Out-of-Sight, Out-of-Mind

There are no accurate figures on how much oil has gushed from the mile-deep Macondo well since April 20, when the Deepwater Horizon, the drilling rig BP rented and directed, failed in an exploding firestorm of gas and oil and sank, killing 11 workers.

But from BP CEO Tony Hayward's May 17 statement that the environmental impact will be "very very modest," to BP's self-satirizing announcements that the amount of captured oil on a particular day exceeded the company's estimate of the amount leaking, BP has downplayed the volume of oil.

Aside from the public relations boon from low balling the flow, BP has a financial incentive: U.S.-government-imposed fines are based on quantity of oil released.

Still there is no way to hide the fact that, even if the well is capped for good, oil is spreading from Texas to Florida, and fouling a fragile, complex, and commercially lucrative environment.

BP has now applied an unprecedented almost one-million-and-counting gallons of chemical dispersants, some sprayed by the US Air Force from two C-130 Hercules cargo planes that can fly three missions a day, and cover up to 250 acres per flight.

And in an unprecedented experiment, a half million gallons of Corexit has been injected a mile deep at the blown-out well head. This untested technique has caused oil to become suspended in great plumes before it reaches the surface, further hiding the quantity of leaked oil. An added bonus of the deep sea application for BP is that marine life killed by the plumes dies out-of-sight, and sinks to the ocean floor, rather than grimly dying on camera in oil-coated misery.

"Right now there is a headlong rush to get this oil out-of-sight, out-of-mind," said Richard Charter, an expert on marine biology and oil spills who is a senior policy advisor for Marine Programs for Defenders of Wildlife and is chairman of the Gulf of the Farallones National Marine Sanctuary Advisory Council.

Corexit: How Much, How Toxic?

BP has used two dispersant formulations in the gulf -- Corexit 9500 and Corexit 9527. Both, according to the manufacturer Nalco Co., contain propylene glycol, which is used in antifreeze, de-icers and detergents. But the older formula, Corexit 9527A -- which contains 2-butoxy ethanol, a compound associated with headaches, vomiting, and reproductive problems at high doses -- is more toxic.

While state and federal agencies have been testing gulf seafood for oil, no one is conducting chemical testing for the presence of dispersants.

Numerous Corexit formulae including 9527 and 9500 were applied to the Alaska shore after the 1989 Exxon Valdez tanker disaster. Their efficacy in cleaning up the oil was limited, and the Alaska Community Action on Toxics later linked the chemicals to human health impacts including respiratory, nervous system, liver, kidney, and blood disorders.

Backing away from the Corexit 9527 formula, a Nalco press release parsed its words carefully (Emphasis added.): "COREXIT 9500 is the sole product we have been making for Gulf responders since the spill began. Limited quantities of COREXIT 9527 may have been drawn from existing dispersant stockpiles from around the world. COREXIT 9500 does not include the ingredient 2-butoxy ethanol, an ingredient in COREXIT 9527."

Given that the company admits selling BP 9527 for use in the gulf, "making" is obfuscating and "may" is just silly.

Asked to define "limited quantities," Nalco senior manager for external communications, Charlie Pajor, said he didn't know. Corexit 9527, he said, was drawn from global stores, and used to fill the gap until Nalco could produce more of the "improved" Corexit 9500. Nor would Pajor say how much of the 9527 formula was available around the world, or has been sold or manufactured in the ten or so years that the Corexit 9500 went on the market.

At the time of the spill, Nalco had only "10,000 gallons of Corexit on hand," he told CorpWatch - roughly a day's worth - so Nalco quickly began ramping up production.

By April 28, eight days after the blowout, "Responders had already used about 56,000 gallons of oil dispersant," according to Chemical News & Intelligence, and, given the limited supply of the Corexit 9500, presumably much of that was the more toxic 9527 formula.

In mid-May, EPA head Jackson said she didn't know for sure how much of each formulation was deployed, but she understood that use so far had been "roughly 50/50." At that point, BP had dispersed at least 400,000 gallons of Corexit.

Garbage In, Garbage Out

Although Nalco had marketed Corexit 9500 since the mid-1990s and the 9527 formula even longer, there is a paucity of good independent data on their short- and long-term effects on the environment, on humans, and on sea life.

Nonetheless, by April 22, even before the extent of the leak became apparent, the EPA had authorized the use of 100,000 gallons of dispersants. Almost 50 days later, public and congressional pressure forced the agency to finally release the ingredients (but not the proportions used) in two Nalco formulae.

The use of dispersants to mitigate oil spills rests on two assumptions-one accurate and the other unproven. The accurate rational is that dispersants break up oil. Under some circumstances, treated oil becomes more biodegradable.

The second assumption -the unproven rational for using dispersants - is that breaking up spilled crude is effective in mitigating the oil's long- and short-term impact, and is less toxic to the environment than other approaches in similar circumstance.

"Decision-making about dispersants," Carys Mitchelmore told the New Orleans Time Picayune, is undermined by “fundamental, basic questions that have not been addressed. Like is it really true that oil is more degradable by bacteria when it's in the small oil droplet form, and is dispersed oil less damaging to birds and marine mammals? There's all kind of conflicting science on both of those questions." Mitchelmore is an associate professor of environmental toxicology and chemistry at the University of Maryland's Chesapeake Biological Laboratory.

As with most chemicals used in the U.S., most of the research data on Corexit comes from industry rather than independent research. In 2009, the nonpartisan Government Accountability Office criticized the EPA for failing to adequately assess risks from thousands of toxic chemicals.

“Under current law, only a few short-term aquatic toxicity tests of dispersants are required … and the EPA is not mandated to assess the safety of dispersants or their ingredients,” charged the non-profit environmental coalition, Safer Chemicals, Healthy Families.

"We're basically rolling the dice with the use of chemical dispersants in the Gulf," said Richard Denison, an Environmental Defense Fund scientist.

In addition to concerns about the safety and efficacy of the dispersants themselves is evidence that the interaction of the dispersants and the oil creates a toxic synergy worse than any of the ingredients alone.

"[A] mixture of oil and dispersant gives rise to a more toxic effect on aquatic organisms than oil and dispersants do alone," suggested a study for the Swedish Environmental Protection Agency. "The research on toxicity of oils mixed with dispersants has, however, shown high toxicity values even when the dispersant per se was not very toxic."

A 1999 report on Corexit 9500 for the Alaska Department of Environmental Conservation Division of Spill Prevention and Response found that under some conditions: "Following dispersant use … the toxicity of the resulting oil residue (on an oil mass basis) may be increased."

Concerned about toxicity, the UK has banned Corexit for off-shore use in the North Sea. The dangers of off-shore use in the Gulf of Mexico include killing fish larvae - including those of imperiled Atlantic bluefin tuna which spawn in the region -- threatening filter-feeders, and disrupting the viability of the region's ecosystem by destroying organisms low on the food chain that sustain larger marine creatures.

Serious as concerns about surface application are, they are dwarfed by the unknowns in applying dispersants far below the surface where water temperatures hover above freezing. A 2006 study found that oil droplets treated with a chemical dispersant did not degrade nearly as fast in frigid water.

Conflicting Data, Research Holes

Lisa Jackson, head of the Environmental Protection Agency (EPA,) which has approved the unprecedented quantities and uses of dispersants, has delivered mixed messages. At one point she asserted that "We know that dispersants are less toxic than oil. We know that surface use of dispersants decreases the risk to shorelines and organisms at the surface when they are properly applied."

But she also acknowledged that, "none of the testing that was done prior to this incident was what I'd call extensive, and geared toward the long-term effects or effects in the sub-sea."

The EPA also acknowledged that no studies had been carried out on how long Corexit 9500 persists in the environment-perhaps even after the oil it was meant to control has biodegraded. "We are currently unaware of published scientific information in the peer-reviewed literature about the biodegradation of the dispersant itself," the agency website noted.

Mitchelmore, who has testified five times to Congress on dispersants since the spill, lamented that the available data on dispersants were an industry-supplied jumble that didn't parse, according to the Times-Picayune: "When I looked at that contingency table, I just couldn't believe it. I thought I must be seeing things, because surely they can't be posting this data," she said.

"There's research out there that shows that dispersed oil is more toxic than the oil itself, and then there are studies that say it's the same," she told McClatchy-Tribune News Service. "The big questions are: What are the long-term or delayed effects, and how will the different routes of oil exposure due to dispersant use affect exposed organisms? Those are topics that really haven't been looked at in detail and were highlighted in the NRC report."

 The 2005 National Research Council report that Mitchelmore worked on summarized current information on dispersants, and called for more research on the effects of dispersant and dispersed oil and on how they impact marine life.

The EPA, which recognizes Corexit as a toxin, had left that research to industry. On May 13, facing charges that safer alternatives to Corexit were available, Jackson said that BP was free to decide which of the 18 agency-approved dispersants it wanted to use. "Our regular responsibilities say, if it's on the list and they want to use it, then they are preauthorized to do so," she said.

Then in a May 20 directive, the EPA announced it "requires BP to identify a less toxic alternative - to be used both on the surface and under the water at the source of the oil leak - within 24 hours and to begin using the less toxic dispersant within 72 hours of submitting the alternative

"BP is using this dispersant in unprecedented volumes and, last week, began using it underwater at the source of the leak -- a procedure that has never been tried before. Because of its use in unprecedented volumes, and because much is unknown about the underwater use of dispersants, EPA wants to ensure BP is using the least toxic product authorized for use."

The company balked at stopping Corexit use, and the EPA, lacking solid research on alternative dispersants, caved. The agency admitted that it could not readily find an effective and safer alternative to Corexit since data in the National Contingency Plan Product Schedule was provided by the companies themselves, and had been criticized as unreliable.

The EPA was reluctant to challenge BP. "If you're going to tie our hands, then we don't own this spill," BP Vice President David Rainey had warned at a May 12 meeting with state officials on BP's dispersant plans, according to Alan Levine, Louisiana secretary of Health and Hospitals and the Jindal administration's point man.

In a corner, Jackson told BP to "establish an overall goal of reducing dispersant application by 75 percent from the maximum daily amount." That careful wording allowed BP to use the day of highest dispersal - 70,000 gallons - as the benchmark. Jackson was then able to accurately (but misleadingly) claim that BP had reduced dispersant use 68 percent. In fact the average daily use has only gone down slightly from 24,700 gallons before the directive to 22,600 after it.

Good News, Bad News

In the first month of the spill, Nalco stock spiked, and estimated sales of Corexit garnered $40 million. Next quarter sales will be released on July 27. Watching with envy, other dispersant manufacturers have cried foul, and linked the exclusive use of Corexit to Nalco's close relationship to BP, rather than to the products' superiority.

Nalco board member Rodney F. Chase, is a nearly four-decade veteran of BP, most recently as a managing director and deputy group chief executive. (A former Exxon Mobil Corp. president is also on Nalco's board of directors.)

"It's a chemical that the oil industry makes to sell to itself, basically," Richard Charter, a senior policy adviser for Defenders of Wildlife, was quoted in a May 13 Greenwire blog.

Members of the U.S. Congress have also questioned BP's exclusive use of Corexit. "Why would you use something that is much more toxic and much less effective, other than you have a corporate relationship with the manufacturer?" asked Jerrold Nadler, a Democrat from New York, during a May 19 committee hearing on the disaster.

"When we came out with a safer product [Dispersit], we thought people would jump on board," said U.S. Polychemical Corp head Bruce Gebhardt in an interview with Greenwire. "That's not the case. We were never able to move anyone of any size off the Corexit product," "We're just up against a giant." His company, Gebhardt said, could make 60,000 gallons a day of Dispersit, which "was formulated to outperform Corexit, and got EPA approval 10 years ago."

BP was still using only Corexit on June 30 when the EPA released tests that determined the eight dispersants it researched "have roughly the same impact on aquatic life." In fact, several were rated slightly less toxic than Corexit.[i]

"We are not making any such recommendation [to tell BP to switch products] at this time," Paul Anastas, EPA's assistant administrator for research and development said in a conference call with reporters. "We will need to have this additional testing of the dispersants plus the oil."

The good news, the EPA concluded, is that the dispersants are no more toxic than the spilled oil. The bad news is that the dispersants are no less toxic than the spilled oil that continues to poison the gulf waters, shores, wildlife, and human livelihoods.