Roughly five million liters of dispersants have now been used to break up the oil spilling into the Gulf of Mexico, making this the largest use of such chemicals in U.S. history. If it continues for 10 months, as long as Mexico's Ixtoc 1 blowout in 1979 in the same region, the Macondo well disaster has a good chance of achieving the largest global use of these chemicals, surpassing 10 million liters.

And there is no doubt that dispersants are toxic: Both types of the dispersal compound COREXIT used in the Gulf so far are capable of killing or depressing the growth of a wide range of aquatic species, ranging from phytoplankton to fish. "It's a trade-off decision to lessen the overall environmental impact," explained marine biologist Jane Lubchenco, director of the National Oceanic and Atmospheric Administration (NOAA), at a press conference on May 12. "When an oil spill occurs, there are no good outcomes."

The trade-off in this case is the addition of toxic chemicals in a bid to protect the marshes of Louisiana and the beaches of Florida. But the U.S. Environmental Protection Agency (EPA), for one, has become concerned about the toxicity of the most-used dispersant at the Gulf of Mexico spill—COREXIT 9500—and ordered BP to look at alternatives. (COREXIT 9527 was used earlier during the spill, but it was discontinued because it was considered too toxic.)

The problem? The EPA's industry-generated data is unclear as to the relative toxicity of various dispersants. "If you think the data on COREXIT is bad, try to find any decent toxicology data on the alternatives," says toxicologist Carys Mitchelmore of the University of Maryland's Chesapeake Biological Laboratory, who helped write a 2005 National Research Council (NRC) report on dispersants. "I couldn't compare and contrast which one was more toxic than the other based on that."

Dispersed oil
Both COREXIT 9500 and 9527 are produced by Naperville, Ill.–based Nalco, a company better known for its water purification work with the oil industry. "For every barrel of oil produced, 3.5 barrels of water are produced," explains chemist Mani Ramesh, chief technology officer for Nalco. "That needs to be treated before it can be released. That water treatment has been a core area for us."

But at the same time Nalco keeps busy cleaning the oil industry's water, it also provides COREXIT, a product to minimize the impact of any oil that spills into the water. Developed in a joint venture with ExxonMobil, the compound is largely made at facilities in Sugarland, Tex., and Garyville, La. The company expects to sell some $40-million worth of COREXIT as a result of the latest spill. "What the dispersant process enables is to prevent the oil from reaching the shore and converts that oil to easy food for naturally occurring microbes," Ramesh says. "If the oil reaches the shore the decomposition rate of oil is so low it would remain on the shore for probably 100 years."

By last week, the EPA and Nalco had both released the ingredient list for COREXIT 9500 in response to widespread public concern. Its constituents include butanedioic acid (a wetting agent in cosmetics), sorbitan (found in everything from baby bath to food), and petroleum distillates in varying proportions—and it decomposes almost entirely in 28 days. "All six [ingredients] are used in day-to-day life—in mouthwash, toothpaste, ice cream, pickles," Ramesh argues. "We believe COREXIT 9500 is very safe."

The U.S. Centers for Disease Control and Prevention agrees, noting in a document for health professionals that "the dispersants contain proven, biodegradable and low-toxicity surfactants," which are "detergentlike" and "in low toxicity solvents."

However, those solvents—petroleum distillates—are also known animal carcinogens, according to toxicology data, and make up 10 to 30 percent of a given volume of COREXIT. And those same everyday products can be deadly to wildlife. "It's the same products in Dawn dishwasher soap," Mitchelmore notes, which is being used widely to clean up oiled birds and other animals. "I wouldn't want to put a fish in Dawn dishwashing soap either. That would kill it."

As a result, the EPA ordered BP to stop spraying dispersants on the oil slick on May 26. The EPA also ordered BP to look for less toxic alternatives on May 20, and the company responded in a letter dated that same day that "BP continues to believe that COREXIT EC9500A is the best alternative." The dispersant continues to be sprayed onto the ongoing oil spill.

No alternative
One reason BP can make such claims is due to a lack of clear data on any of the alternative dispersants. As part of the National Contingency Plan required for offshore drilling, one of 18 EPA-approved dispersants must be on hand to handle spilled oil. Each of those dispersants has been preapproved for use, and each of those dispersants has been tested—by the companies that make them—for toxicity using representative species of estuarine shrimp (Mysidopsis bahia) and fish (Menidia beryllina). Specifically, these animals are exposed to a mix of one liter of dispersant for every 10 liters of heavy fuel oil in water.

Yet, the results of those tests vary wildly, from toxic impacts occurring at levels of just 2.6 parts per million for COREXIT to 100 ppm for another dispersant, NOKOMIS 3-F4. That suggests to experts that the tests which showed lower toxicity may have employed heavy fuel oil that had lost its potency. After all, volatile organic compounds in oil evaporate quickly when exposed to air and can even wash off in water. "These are order of magnitude differences," Mitchelmore notes. "A lot of that can relate to how those tests were set up."

Adds Nalco toxicologist Sergio Alex Villalobos, "If the oil is aged, then the oil loses its toxicity. Using an oil that is not very toxic, if you disperse that oil you are going to get very favorable numbers. Do those numbers really exist?"

EPA, for its part, did not show the best understanding of toxicological data in making its recommendations, urging BP to use dispersants with less than a certain cutoff of toxicity (pdf). Of course, in toxicology the lower the concentration the more toxic a given substance is. "They completely got that wrong," Mitchelmore says. EPA is now undertaking its own toxicology testing of COREXIT and Louisiana crude oil, but results are pending.

Nevertheless, just 20 ppm of COREXIT 9500—or one drop in 2.5 liters of water—inhibits growth of Skeletonema costatum, a Gulf of Mexico diatom, according to toxicology test data presented in the 2005 NRC report. It appears to inhibit the phytoplankton's ability to perform photosynthesis, specifically blocking part of the biochemistry that enables the photosystem II complex, Villalobos says. "Skeletonema seems to fall among the most sensitive ones," he says. "Like many aquatic plants, these are organisms that are resilient, that tend to come back even though you wipe them out in some cases chemically."

COREXIT is also not approved for use in U.K. waters because it fails the so-called "limpet test". That test involves spraying the dispersant and oil on rocks and seeing if limpets (a type of small mollusk) can still cling to them, a test which COREXIT and many other dispersants with slippery surfactants fail. "This is not a product for rocky shores," Villalobos says. "These are only for open sea waters."

Novel use
Of course, in the case of the oil spewing from BP's Macondo well in the Gulf of Mexico, COREXIT is being used in another unapproved way. A wand from one of the remote-operated robots has sprayed more than 1.5 million liters of dispersants directly onto the escaping oil and natural gas roughly 1,500 meters beneath the ocean's surface. "I don't think anybody knows what would happen by applying the dispersants at depth," Ramesh says. "We do not have any knowledge that would allow us to predict what would happen."

In addition to creating subsurface plumes (and providing a rich feast for oil-eating microbes), it remains unclear what kind of dosage of dispersed oil sea life throughout the water column is facing. NOAA measurements show that levels reach 100 ppm of dispersed oil in the first half-meter of water, dropping to 12.5 ppm at 10 meters and unknown levels even deeper. "There isn't any information on what is the environmentally relevant level of dispersant," Mitchelmore notes. "Dispersed oils are going to be toxic, particularly in the top 10 meters that contains all the sensitive life stages. Anything that has sensitive membranes can be affected by dispersants and dispersed oil."

Sunlight falling on the dispersed oil may make the problem worse through a phenomenon known as phototoxicity. Compounds in the oil act as a catalyst to transfer some of the sun's energy into oxygen, converting the latter to a more reactive state that can literally burn up cells. And as fish and other sea life ingest the dispersed oil, it can be broken down into more toxic by-products. "What do these things break down into?" Mitchelmore says. "In toxicology it's quite often not the original compound that's the toxic entity."

Ultimately, the problem is that too little is known about the dispersants and the dispersed oil. "Given that this is a billion-dollar industry, why were those data gaps not filled?" Mitchelmore asks. "The whole issue regarding limited toxicity data—that's not just common to dispersants, that's common to tens of thousands of chemicals we're putting out into the environment daily."

After all, it was only after decades of using bisphenol A, polybrominated flame retardants and other chemicals that significant concerns began to manifest. In effect, usage replaced safety testing—and that's exactly what is happening with dispersants and the massive spill in the Gulf. Different regulation of chemicals and the chemical industry might forestall toxicological mysteries like those surrounding dispersants—and their thousands of chemical cousins—in the future.

"We're using an awful lot of dispersants," said EPA administrator Lisa Jackson during the same May 12 press briefing on the chemical's use at which NOAA's Lubchenco spoke. "This is going on longer than one might have known on day three or four. We're still dealing with a constant release of fresh oil and we need to continue to disperse."

22 Comments

1. 1. frgough 04:59 PM 6/18/10

   Typical over the top rhetoric by SA. No, it is NOT a given that the dispersants are toxic. SOME studies have shown the POSSIBILITY of toxicity in CERTAIN types of plants and animals.
   
   And, of course, let's just ignore the willful scientific malpractice on the part of SA in pretending oil and dispersants are as eternal as God and will exist in the oceans ten million years from now.
   
   SA. Doing Pravda proud.

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2. 2. quincykim 06:14 PM 6/18/10

   Given the lack of specifics regarding toxicity of the dispersants, their ability to mask the extent of the plume, not to mention the existence of natural oil-eating microbes, the decision to use dispersants seems shortsighted and ultimately counterproductive. It replaces a known problem with an unknown mix, without having enough knowledge to see past the "it doesn't look so yucky now" stage.
   
   Equating SA with Pravda is overblown and pointless, but I've noticed that this author (David Biello) has a history of writing emotional, poorly documented articles, which is not in the SA tradition of old.

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3. 3. msavage 09:39 PM 6/18/10

   How about, Bottom Line&supply respirators for workers!! Please learn from my experience and do not end this spill cleanup with workers as BP's Collateral Damaged.
   
   My letter to Gulf residents.
   http://www.urbanconservancy.org/letters/gulf-coast-cleanup-caution-urged
   
   The crude oil is toxic, and anyone who cleans the oily Gulf beaches needs to know the danger.
   http://www.lvrj.com/news/exxon-valdez-oil-risks-spur-warning-for-gulf-cleanup-crews-93258964.html
   
   My name is Merle Savage, a female general foreman during the Exxon Valdez oil spill (EVOS) beach cleanup in 1989. I am one of the 11,000+ cleanup workers, who is suffering from health issues from that toxic cleanup, without compensation from Exxon.
   
   Dr. Riki Ott visited me in 2007 to explain about the toxic spraying on the beaches, and informed me that Exxon's medical records that surfaced in litigation by sick workers in 1994, had been sealed from the public, making it impossible to hold Exxon responsible for their actions. http://video.google.com/videoplay?docid=5632208859935499100
   
   Beach crews breathed in crude oil that splashed off the rocks and into the air -- the toxic exposure turned into chronic breathing conditions, central nervous system problems, neurological impairment, chronic respiratory disease, leukemia, lymphoma, brain tumors, liver damage, and blood disease. http://www.silenceinthesound.com/stories.shtml
   
   My web site is devoted to searching for EVOS cleanup workers who were exposed to the toxic spraying, and are suffering from the same illnesses that I have. Our summer employment turned into a death sentence for many  and a life of unending medical conditions for the rest of Exxons Collateral Damaged.
   
   

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4. 4. Semiahmoo 10:37 PM 6/18/10

   At most, all the dispersants do is spread the dirt around. It doesn't magically disappear into the aether. The dispersants are poisonous or at the very least, irritating to whatever wildlife still exists. The dispersants do, however, make a great deal of money for the petrochemical companies that produce them. Are they made by a BP subsidiary? Dispersants mobilize the spill, allowing it to spread much farther than it would have. Bad idea from all angles.

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5. 5. Marshman 07:50 AM 6/19/10

   My gut feeling is that the main purpose of using dispersants was to conceal the magnitude of the leak from the public. One of BP's liabilities is to pay ~$300 or more per barrel leaked, so "dispersing" it would make it difficult to account for. With dispersants, the oil sinks and actually more easily avoids booms and skimming, and winds up in marshes anyway, as well as sinking into the deep beyond our ability to collect. My guess is that this treatment has only compounded the problem. I can only imagine the horrific impact this is going to have on marine life, and how it will all wind up in the food chain.

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6. 6. tranche 08:14 PM 6/19/10

   Does Sciam moderate comments? The comment by Hyperstig would be something I would assume a magazine of this regard should put a hold on.

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7. 7. JoeyC in reply to Marshman 10:35 PM 6/19/10

   Correct you are.

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8. 8. JoeyC in reply to Semiahmoo 10:46 PM 6/19/10

   It is a given they are extremely toxic to almost all marine life, any study that has demonstrated anything different is not legit and serves the manufactures bottom line. Yes you are correct they are not Eternal, of course SA never said they were. But the effect will be felt in our ocean for hundreds of years. Funny how quickly mankind will sell his morals for a buck.

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9. 9. JoeyC 11:26 PM 6/19/10

   Everything BP does serves their bottom line...net profits. When you take that into account it becomes all to clear why toxic dispersants are used......they will save money by using them. How can this save them money? By keeping the horrendous impact to our enviroment hidden under the oceans rather then thrown in our faces by the media as it hits the beaches. Under the water, in the undersea currents it will go somewhere else and BP can go, "I dunno"....plausible deniabilty, way harder for anyone to prove where it came from. So we loose a gulf, some wetlands, a reef or two, in a thousand years you won't even be able to tell....almost. It was worth it so as BP should show a greater profit....right? Sick. Sick. Sick.

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10. 10. frgough in reply to JoeyC 05:43 PM 6/20/10

    "It is a given they are extremely toxic to almost all marine life, any study that has demonstrated anything different is not legit and serves the manufactures bottom line. Yes you are correct they are not Eternal, of course SA never said they were. But the effect will be felt in our ocean for hundreds of years. Funny how quickly mankind will sell his morals for a buck."
    
    
    Part one is a shoot the messenger fallacy. I can play that game, too: Any study claiming dispersants are extremely toxic to all marine life are the result of leftist green nazis in universities.
    
    And, no, the effects will not be felt for hundreds of years. Try less than ten. Go look at some pictures of Prince William Sound.

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11. 11. frgough 05:46 PM 6/20/10

    Ignorance is the true crisis in our society today. It allows propagandists to manipulate the populace.
    
    Dispersants are NOT used to "hide" the magnitude of the spill, but rather to decrease the surface area to volume ratio so that the natural elements in ocean water that continually break down the millions of gallons of crude oil that leak from the ocean floor in natural seeps can more effectively eliminate this particular spill. It's standard technique to break up a slick in ocean environments and allow them to biodegrade more quickly.
    
    Oh. Wait. You didn't know oil was biodegradeable?

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12. 12. Shackdarn 09:03 PM 6/20/10

    Anonymous comments from Tony Hayward (paraphrase: "Corexit is harmless! I put it in my breakfast oatmeal for extra zip!") and Sarah Palin (quantum theory explications) in the same thread.
    
    Who knew SA got such prestigious traffic?

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13. 13. JoeyC 10:10 PM 6/20/10

    To those who should try to say BP used dispersants to help natural microbiological activity help break down the oil are really not even worth debating with as they know little in regards to the facts. Kinda like Sarah Palin and death panels. Staying on the surface actually helps the microbes responsible for breaking down the oil which takes hundreds of years. Lot's of different compounds in crude oil. As far as Prince Willam Sound goes you just have to dig a little to still find oil a thick layer on the shore according to the locals.

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14. 14. earthspeakorg 11:00 PM 6/20/10

    I believe the dispersants come with instructions to wear protective gear and not to breathe the fumes. BP is not giving workers masks or even allowing workers to wear them. Dispersants also were not intended to be used for such a long time or such a large amount. EPA is dropping the ball on this one! Does our government serve the people or the corporate masters?

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15. 15. earthspeakorg 11:03 PM 6/20/10

    I believe the dispersants come with instructions to wear protective gear and not to breathe the fumes! Also, do not think they were ever intended to be used for so long or on such a large amount. EPA is really dropping the ball on this one!

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16. 16. galaxy_man in reply to earthspeakorg 08:58 AM 6/22/10

    The more I learn about the practices and policies of the EPA, the more I come to believe they never had the ball to begin with.

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17. 17. Fabrice LOTY 12:07 PM 6/22/10

    In the face of such catastrophe, it is appropriate to structure adequate technical response capabilities.
    As a result, the coming generations inheriting a weakened environment will also inherit the ability to mitigate the risk of further, unsustainable damages. This is the minimum agreement the industry should comply with.
    For instance, is it not possible to equip submersible robots with dispersing capability? Working near the point of impact, they would disperse oil within an already polluted area, thus sparing wetlands sizable damages, perceived or substantial.
    

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18. 18. udaybhawalkar 01:07 AM 7/4/10

    Dropping BioSanitizer Ecochips in the affected area, will start ecoremediation reactions that will convert the pollution into food(and oxygen) for the aquatic ecology. For details, please see www.biosanitizer.org
    
    This technology has been developed by Dr Uday Bhawalkar from India, 'in collaboration with nature'. Nature has evolutionary experience of 4.5 billion years, so we should consult nature whenever we get overwhelmed with such pollution problems.
    
    The technology has been well demonstrated in field conditions, in India as well as in several other countries, over the past 24 years.
    
    The BioSanitizer Ecochips are insoluble bio-catalyst, so do not introduce any extra pollution. They just 'convert pollution into resources', using laws of nature.

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19. 19. Vag Shantharam Shenai 11:22 PM 7/6/10

    There is an original approach possible where the leaked oil is transformed into fish food. BIOSANITIZER is an innovation of Dr. Uday Bhawalkar of the Bhawalkar Ecological Research Institute in Pune, India. I have personally witnessed its use in sewage plants of Nashik city and a golf course and seen the floating oil go below detectable limit. I urge those readers to go to his website www.wastetohealth.com and understand that the possibility is real and should be used as its non toxic, and even absorbs carbon dioxide when healing the issue. yours sincerely, Vag Shantharam Shenai

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20. 20. daffy 07:29 AM 7/9/10

    the problem is, in the main, organic and therefore the solution has to be organic if load on the vitiated environment is not to increase.
    have used biosanitiser (soil bio-technology product, made in india) to produce oxygen from the air, eliminating the oxygenating pump in a fish tank. apart from remediating sewage/sullage/kitchen waste and eradicating pests, the killer biosanitiser apps is the near-elimination of odour from the loo of a rail terminus in mumbai with a million-plus bladders going through twice a day:-)
    imho, biosanitiser will 'crack' the problem, mitigate the damage and correct the disturbed ecology fastest. any altruist willing to put eu 100,000 down the drain, er.. pacific ocean, for a test run may become the planet's saviour.

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21. 21. Bisphenol-A 12:37 AM 8/3/10

    With or without Corexit (see: Safety Date Sheet http://www.deepwaterhorizonresponse.com/posted/2931/Corexit_EC9527A_MSDS.539295.pdf ), it's doubtful oil would all 'rise' at wellhead subsurface pressures. The temperatures also factor in, as they do with Corexit's unspecified added warnings re heat.
    
    The mixture is said to be more toxic than either oil or Corexit alone, with no studies re temps or salinity. The methane releases just asphyxiate marine life.
    
    So, the evaporation of the Gulf also is worrisome. To liken Corexit to Dawn dish soap is ridiculous. Dish soap does not result in rectal bleeding, membrane damage, etc. (See: Safety Data Sheet.)
    
    Please check: Loop current broken
    Gianluigi Zangari
    Frascati National Laboratories (LNF) - National Institute of Nuclear Physics (INFN)
    Frascati 00044, Via E. Fermi, 40, ITALY
    
    http://www.sott.net/articles/show/212458-Gulf-of-Mexico-Loop-Current-Broken-Risk-of-Global-Climate-Change-By-BP-Oil-Spill-
    
    http://www.associazionegeofisica.it/OilSpill.pdf
    
    The migratory birds are on their way to the Gulf now.

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22. 22. Bisphenol-A 01:10 AM 8/3/10

    Project "Deep Spill" - A joint industry project (JIP) was formed between the MMS and 23 different oil companies to conduct this research. The project consisted of an experimental release of oil and gas conducted in June 2000 off the coast of Norway. Mixtures of crude oil and natural gas, diesel oil and natural gas, as well as only natural gas were released at approximately 800 meters water depth. The goal was to simulate a blowout or pipeline rupture in deep water and obtain data to verify the predictions of a deep water blowout model being developed under a separate contract.
    
    It is already known through laboratory experiments that oil and gas behave differently under the high pressures and low temperatures of deep water than at shallower depths. The results obtained from the experiments will provide baseline data to help establish new and validate existing spill management computer models that would be used to guide clean-up efforts in the unlikely event of an accidental release during actual drilling and production operations.
    
    http://www.boemre.gov/tarprojects/377.htm
    
    This is before the Bush administration deregulated the oil & gas industry. There was no risk assessment for this project, no relief wells, a faulty BOP, a cheap cap, single barrier cement casing (Halliburton), insufficient centralizers (6 not 21), cronyism with MMS, RIK kickbacks, to name a few criminally negligent practices.

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