Corexit (often styled COREXIT) is a product line of oil dispersants used to dissolve oil spills. It is produced by Nalco Holding Company, which merged with Ecolab in 2011 and is associated with BP and Exxon. Oil that would normally rise to the surface of the water is emulsified into tiny droplets by the dispersant and remains suspended in the water and on the sea floor. Corexit was used in unprecedented quantities during the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. In 2012, a study found that Corexit increases the toxicity of oil by 52 times.
The use of Corexit is approved in the US by the U.S. Environmental Protection Agency (EPA). This decision was called into question in 2013 following a report by the Government Accountability Project alleging "devastating long-term effects on human health and the Gulf of Mexico ecosystem" stemming from the use of Corexit.
Corexit has been banned for use on oil spills in the UK since 1988. UK authorities have an approved list of products which must pass both "sea/beach" and "rocky shore" laboratory toxicity tests; Corexit did not pass the rocky shore test. The country of Sweden has also banned its use.
Deepwater Horizon oil spill
On May 19, 2010 the EPA gave BP 24 hours to choose less toxic alternatives to Corexit, selected from the list of EPA-approved dispersants on the National Contingency Plan Product Schedule, and begin applying them within 72 hours of EPA approval of their choices; or, if BP could not find an alternative, to provide a report on the alternative dispersants investigated and reasons for their rejection. BP took the latter option, sending its report the next day. On May 26, the EPA told BP to reduce the use of Corexit by 75%; surface use was prohibited unless a request for exemption in specific circumstances was granted, while subsurface use was capped at 15,000 gallons per day. After May 26 daily average use dropped instead to 9%, a little more than 23,000 gallons per day.
In April 2010, BP had bought up one-third of the world supply of Corexit. By late May 2010, BP had reportedly applied 800,000 US gallons total, but more accurate estimates run as high as 1,000,000 US gallons.
The end total figure was 1.84 million gallons of Corexit EC9500A and Corexit EC9527A, with roughly 58% sprayed from the air.
At the beginning of the Gulf spill, the proprietary composition was not public, but the manufacturer's own safety data sheet identified the main components as 2-butoxyethanol and a proprietary organic sulfonate with a small concentration of propylene glycol. Warnings from the Hazardous Substance Fact Sheet for 2-Butoxyethanol include: "Cancer Hazard: 2-Butoxy Ethanol may be a carcinogen in humans since it has been shown to cause liver cancer in animals. Many scientists believe there is no safe level of exposure to a carcinogen....Reproductive Hazard: 2-Butoxy Ethanol may damage the developing fetus. There is limited evidence that 2-Butoxy Ethanol may damage the male reproductive system (including decreasing the sperm count) in animals and may affect female fertility in animals". 2-butoxyethanol was identified as a causal agent in the health problems experienced by cleanup workers after the 1989 Exxon Valdez oil spill. According to the Alaska Community Action on Toxics, the use of Corexit during the spill caused people "respiratory, nervous system, liver, kidney and blood disorders".
In response to public pressure, the EPA and Nalco released the list of the six ingredients in Corexit 9500, revealing constituents including sorbitan, butanedioic acid, and petroleum distillates. Corexit EC9500A is made mainly of hydrotreated light petroleum distillates, propylene glycol and a proprietary organic sulfonate. According to the New York Times, "Nalco had previously declined to identify the third hazardous substance in the 9500 formula, but EPA's website reveals it to be dioctyl sodium sulfosuccinate, a detergent and common ingredient in laxatives". Environmentalists also pressured NALCO to reveal to the public what concentrations of each chemical are in the product; NALCO considered such information a trade secret, but shared it with the EPA.
Earthjustice and Toxipedia Consulting Services conducted the first analysis of the 57 chemicals found in Corexit formulas 9500 and 9527 in the summer of 2011. Results showed the dispersant could contain cancer-causing agents, hazardous toxins and endocrine-disrupting chemicals. The analysis found "5 chemicals are associated with cancer; 33 are associated with skin irritation from rashes to burns; 33 are linked to eye irritation; 11 are or are suspected of being potential respiratory toxins or irritants; 10 are suspected kidney toxins; 8 are suspected or known to be toxic to aquatic organisms; and 5 are suspected to have a moderate acute toxicity to fish”.
Chemist Wilma Subra expressed her concern about the danger of the Corexit-crude mixture, telling GAP investigators, “The short-term health symptoms include acute respiratory problems, skin rashes, cardiovascular impacts, gastrointestinal impacts, and short-term loss of memory....long-term impacts include cancer, decreased lung function, liver damage, and kidney damage.”
Prior to the 2010 Gulf spill, the majority of studies performed on Corexit tested for effectiveness in dispersing oil, rather than for toxicity. The manufacturer's safety data sheet states "No toxicity studies have been conducted on this product," and later concludes "The potential human hazard is: Low." According to the manufacturer's website, workers applying Corexit should wear breathing protection and work in a ventilated area.
Compared with 12 other dispersants listed by the EPA, Corexit 9500 and 9527 are either similarly toxic or 10 to 20 times more toxic. In a preliminary EPA study of eight different dispersants, Corexit 9500 was found to be less toxic to some marine life than other dispersants and to break down within weeks, rather than settling to the bottom of the ocean or collecting in the water. None of the eight dispersants tested were "without toxicity", according to an EPA administrator. During the 2010 spill, the ecological effect of mixing the dispersants with oil was unknown, as was the toxicity of the breakdown products of the dispersant.
Rhode Island Sen. Sheldon Whitehouse claimed the EPA was "woefully unprepared" to make the decision to allow BP's use of Corexit. He noted that EPA's "approved" list of dispersants required only that the manufacturer nominate itself and provide data proving its efficacy. The dispersant manufacturer must provide its own toxicity data, however no threshold exists that would disqualify a dispersant.
Nalco spokesman Charlie Pajor said that oil mixed with Corexit is "more toxic to marine life, but less toxic to life along the shore and animals at the surface" because the dispersant allows the oil to stay submerged below the surface of the water. Corexit causes oil to form into small droplets in the water; fish may be harmed when they eat these droplets. According to its Material safety data sheet, Corexit may also bioaccumulate, remaining in the flesh and building up over time. Thus predators who eat smaller fish with the toxin in their systems may end up with much higher levels in their flesh. The influence of Corexit on microbiological communities is a topic of ongoing research.
Corexit 9527, considered by the EPA to be an acute health hazard, is stated by its manufacturer to be potentially harmful to red blood cells, the kidneys and the liver, and may irritate eyes and skin.
Like 9527, 9500 can cause hemolysis (rupture of blood cells) and may also cause internal bleeding. According to BP data, 20 percent of offshore workers had levels of 2-Butoxyethanol two times higher than the level certified as safe by the Occupational Safety and Health Administration.
According to the EPA, Corexit is more toxic than dispersants made by several competitors and less effective in handling southern Louisiana crude.
During a Senate hearing on the use of dispersants, Senator Lisa Murkowski asked EPA administrator Lisa P. Jackson whether Corexit use should be banned, stating she didn't want dispersants to be "the Agent Orange of this oil spill".
According to a NALCO manual obtained by GAP, Corexit 9527 is an “eye and skin irritant. Repeated or excessive exposure ... may cause injury to red blood cells (hemolysis), kidney or the liver.” The manual adds: “Excessive exposure may cause central nervous system effects, nausea, vomiting, anesthetic or narcotic effects.” It advises, “Do not get in eyes, on skin, on clothing,” and “Wear suitable protective clothing.” For Corexit 9500 the manual advised, “Do not get in eyes, on skin, on clothing,” “Avoid breathing vapor,” and “Wear suitable protective clothing.” Neither the protective gear, nor the manual were distributed to Gulf oil spill cleanup workers, according to FOIA requests obtained by GAP.
In late 2012, a study from Georgia Tech and Universidad Autonoma de Aguascalientes, Mexico reported that Corexit used during the BP oil spill had increased the toxicity of the oil by 52 times. The leader of the study, Roberto-Rico Martinez (UAA), said “Dispersants are pre-approved to help clean up oil spills and are widely used during disasters....but we have a poor understanding of their toxicity. Our study indicates the increase in toxicity may have been greatly underestimated following the Macondo well explosion”.
A study released by Florida State University and Utrecht University, Netherlands in November 2012, found Corexit made oil sink faster and more deeply into the beaches, and possibly groundwater supplies. The researchers found that Corexit 9500A allowed the toxic components of crude oil (PAHs) to permeate sand where, due to a lack of sunlight, degradation is slowed. The authors explained, "The causes of the reduced PAH retention after dispersant application has several reasons: 1) the dispersant transforms the oil containing the PAHs into small micelles that can penetrate through the interstitial space of the sand. 2) the coating of the oil particles produced by the dispersant reduces the sorption to the sand grains, 3) saline conditions enhance the adsorption of dispersant to sand surfaces, thereby reducing the sorption of oil to the grains".
A 2012 study clearly suggests that Corexit is highly toxic to early life stages of coral. From the paper, "Even at a low concentration (0.86 ppm) of oil-dispersant mixture diluted over 96 hours, most of the mountainous star coral did not survive".
Surfrider Foundation released preliminary results of their study "State of the Beach" in which they found that Corexit appears to make it tougher for microbes to digest the oil. From the report: The use of Corexit is inhibiting the microbial degradation of hydrocarbons in the crude oil and has enabled concentrations of the organic pollutants known as PAH to stay above levels considered carcinogenic by the NIH and OSHA. Through the use of 'newly developed' UV light equipment, researchers were able to detect PAH's in sand and on human skin. Corexit, they said, allows these toxins to absorb into the skin and cannot be wiped off. The mixture of Corexit and crude absorbs into wet skin faster than dry.
In 2012, researchers for the Minnesota Department of Natural Resources found evidence of petroleum compounds and Corexit components in the eggs of nesting pelicans that had migrated to the Gulf of Mexico and back to Minnesota. Because Corexit is an endocrine disruptor, researchers said the chemicals can disrupt hormone balance and affect embryo development.
When oil is dispersed, it is distributed in three dimensions (in the water column) rather than just two (on the surface). USF scientists found that the untested undersea application of the dispersant created abundant oil plumes in the middle of the Gulf of Mexico. In 2013 it was reported that everywhere the plumes had drifted, a massive die-off was left in the wake. Millions of amoeba-like creatures called foraminifera, the basis of the Gulf food chain, were killed by the plume.
A study of 247 BP oil spill clean-up workers, released in September 2013 by the American Journal of Medicine, showed the workers were at an increased risk of developing cancer, leukemia and other illnesses. The study concluded that "clean-up workers exposed to the oil spill and dispersant experienced significantly altered blood profiles, liver enzymes, and somatic symptoms.
According to the EPA, Corexit EC9500A (formerly "Corexit 9500") was 54.7% effective, while Corexit EC9527A was 63.4% effective in the dispersion of Louisiana crude. The EPA lists 12 other dispersants as being more effective in dealing with oil in a way that is safe for wildlife.
Evidence from researchers at Woods Hole Oceanographic Institute showed Corexit did not degrade as promised. Studies conducted in January 2011 indicated that the 800,000 gallons of Corexit applied at BP's Macondo well-head "did nothing to break up the oil and simply drifted into the ecosystem".
In April 2012, Center for Biological Diversity, the Surfrider Foundation, and Pacific Environment filed a lawsuit against the EPA and the U.S. Coast Guard, claiming the agencies failed to adequately study the chemicals in Corexit and dispersed oil with regard to environmental effects.
U.S. District Judge Carl Barbier in December 2012 dismissed all claims against the manufacturer of Corexit, stating that such claims would become an "obstacle to federal law". Barbier held that Nalco did not determine how and in what quantities Corexit was administered during the Deepwater Horizon oil spill.
EPA whistleblower Hugh Kaufman gave an interview to Democracy Now during the height of the Deepwater Horizon Oil Spill news coverage and explained his views on the use of Corexit, saying "EPA now is taking the position that they really don’t know how dangerous it is, even though if you read the label, it tells you how dangerous it is. And, for example, in the Exxon Valdez case, people who worked with dispersants, most of them are dead now. The average death age is around fifty. It’s very dangerous, and it’s an economic — it’s an economic protector of BP, not an environmental protector of the public."
Marine toxicologist Riki Ott blamed BP for poisoning locals with Corexit, which she alleges they used to hide their responsibility. In August 2010 she wrote an open letter to the Environmental Protection Agency alleging that dispersants were still being used in secret and demanding that the agency take action. The letter was published in the Huffington Post. Ott told Al Jazeera, "The dispersants used in BP's draconian experiment contain solvents, such as petroleum distillates and 2-butoxyethanol. Solvents dissolve oil, grease, and rubber. It should be no surprise that solvents are also notoriously toxic to people, something the medical community has long known."
- PAUL QUINLAN of Greenwire (2010-05-13). "Less Toxic Dispersants Lose Out in BP Oil Spill Cleanup". NYTimes.com. Retrieved 2010-06-10.
- Gaelin Rosenwaks (June 5, 2010). "Oil spill's environmental costs". torontosun.com. Toronto Sun. Retrieved June 25, 2010.
- Corexit: Deadly Dispersant in Oil Spill Cleanup - Government Accountability Project
- Why Is the Toxic Dispersant Used After BP's Gulf Disaster Still the Cleanup Agent of Choice in the US? | Mother Jones
- David Biello (18 June 2010). "Is Using Dispersants on the BP Gulf Oil Spill Fighting Pollution with Pollution?". scientificamerican.com. Scientific American. Retrieved 19 June 2010.
- Gulf of Mexico clean-up makes 2010 spill 52-times more toxic; Mixing oil with dispersant increased toxicity to ecosystems
- Study: Mixing oil with dispersant made the BP oil spill worse | Science Recorder
- GT | Newsroom - Gulf of Mexico Clean-Up Makes 2010 Spill 52-Times More Toxic
- Exposure of Oysters, Crabs, Shrimp, and Red Snapper to Corexit 9500:
- Juliet Eilperin. "Post Carbon: EPA demands less-toxic dispersant". views.washingtonpost.com (The Washington Post). Retrieved June 26, 2010.
- New York Times, "less toxic dispersants lose out in BP oil spill cleanup", May 13, 2010
- Mark Guarino (May 15, 2010). "In Gulf oil spill, how helpful – or damaging – are dispersants?". CSMonitor.com. Christian Science Monitor. Retrieved 26 June 2010.
- In Gulf Spill, BP Using Dispersants Banned in U.K. - ProPublica
- Oil spill treatment products approved for use in the United Kingdom. Marine Management Organisation. May 18, 2010. Retrieved June 13, 2010.
- Corexit: Deadly Dispersant in Oil Spill Cleanup | Climate Science Watch
- "National Contingency Plan Product Schedule". Environmental Protection Agency. 2010-05-13. Retrieved 2010-05-21.
- "Dispersant Monitoring and Assessment Directive - Addendum 2".
- "BP response to EPA Monitoring and Assessment Directive - Addendum 2"
- BP Used Much Dispersant Despite E.P.A. Directive of Rarely - NYTimes.com
- "EPA Dispersant Monitoring and Assessment Directive ‐ Addendum 3"
- CNN.com - Transcripts
- Chemicals Meant To Break Up BP Oil Spill Present New Environmental Concerns - ProPublica
- Corexit: An Oil Spill Solution That Is Worse Than The Problem?
- Paul Quinlan (2010-05-24). "Secret Formulas, Data Shortages Fuel Arguments Over Dispersants Used for Gulf Spill". New York Times. Retrieved 2010-05-24.
- Juliet Eilperin (2010-05-20). "Post Carbon: EPA demands less-toxic dispersant". Washington Post. Retrieved 2010-05-20.
- What BP Doesn’t Want You to Know About the 2010 Gulf Spill - Newsweek and The Daily Beast
- Microsoft Word – 0275.doc. (PDF). Retrieved 2011-04-07.
- "Chemicals Meant To Break Up BP Oil Spill Present New Environmental Concerns". ProPublica. Retrieved 2010-05-07.
- Schor, Elana (9 June 2010). "Ingredients of Controversial Dispersants Used on Gulf Spill Are Secrets No More". The New York Times (The New York Times Company). Retrieved 2010-07-02.
- Elana Schor (June 9, 2010). "Ingredients of Controversial Dispersants Used on Gulf Spill Are Secrets No More". nytimes.com (New York Times). Retrieved June 25, 2010.
- Nalco Releases Additional Technical Information About COREXIT
- "Safety Data Sheet Product Corexit EC9500A". Nalco. p. 1. Retrieved 2010-05-16.
- Schor, Elana (2010-06-09). "Ingredients of Controversial Dispersants Used on Gulf Spill Are Secrets No More". The New York Times.
- Anne Mulkern (June 25, 2010). "Maker of Controversial Dispersant Used in Gulf Oil Spill Hires Top Lobbyists". nytimes.com (New York Times). Retrieved June 25, 2010.
- Pensacola News Journal: Archives
- Impact of Gulf Spill's Underwater Dispersants Is Examined - NYTimes.com
- Oil dispersants used in Gulf of Mexico spill causing alarm | al.com
- "Safety Data Sheet Product Corexit EC9500A". Nalco. pp. 5–6. Retrieved June 11, 2010.
- Sanjay Gupta (June 10, 2010). "Anderson Cooper 360: Blog Archive - How will the oil spill affect my health?". cnn.com. Retrieved June 25, 2010.
- CNN Wire Staff (June 30, 2010). "Dispersants appear to break up in Gulf, EPA says". CNN.com (CNN). Retrieved July 1, 2010.
- EPA official defends role of dispersants in Gulf of Mexico oil spill response | NOLA.com
- "Nalco dispersant makes oil more toxic to marine life, group says". dailyherald.com. Daily Herald. June 15, 2010. Retrieved June 25, 2010.
- Bill Riales (June 18, 2010). "BP Dispersant Getting Independent Lab Test". wkrg.com. WKRG News 5. Retrieved June 25, 2010.
- Fulmer, P. A.; Hamdan, L. J.: Effects of COREXIT EC9500A on bacterial communities influenced by the Deepwater Horizon oil spill, AGU Fall Meeting Abstracts, December 2010
- Corexit 9527 - National Library of Medicine HSDB Database
- Shelley DuBois (June 15, 2010). "Company profile of NALCO, maker of Corexit for BP oil spill". cnn.com (Fortune). Retrieved June 25, 2010.
- "Material Safety Data Sheet: Corexit EC9527A". NALCO. May 11, 2010. Retrieved May 30, 2010. "may cause injury to red blood cells (hemolysis), kidney or the liver"
- "Less toxic dispersants lose out in bp oil spill cleanup", The New York Times, May 13, 2010
- Courthouse News Service
- Review Of The Use Of Dispersants In Response To The Deepwater Horizon Oil Spill
- Use of Dispersants in Gulf Oil Spill, Researchers Panel - C-SPAN Video Library
- BP oil spill dispersants may have hurt Gulf of Mexico food chain, study finds | NOLA.com
- Chemical Dispersant Made BP Oilspill 52 Times More Toxic | Mother Jones
- PLOS ONE: Dispersants as Used in Response to the MC252-Spill Lead to Higher Mobility of Polycyclic Aromatic Hydrocarbons in Oil-Contaminated Gulf of Mexico Sand
- How attempts to clear up the Deepwater Horizon spill may have made it WORSE | Mail Online
- Deepwater Horizon oil, dispersant toxic to coral in Keys - Tampa Bay Times
- PLOS ONE: Toxicity of Deepwater Horizon Source Oil and the Chemical Dispersant, Corexit® 9500, to Coral Larvae
- Did BP's oil-dissolving chemical make the spill worse? | HeraldTribune.com
- Did BP's oil-dissolving chemical make the spill worse? | HeraldTribune.com
- BP's Corexit Oil Tar Sponged Up by Human Skin | Mother Jones
- BP oil spill residue found on pelicans in Minn. | Minnesota Public Radio News
- "Tests suggest Minn. pelicans exposed to oil contaminants in Gulf | Minnesota Public Radio News". Minnesota.publicradio.org. 2012-11-28. Retrieved 2013-04-22.
- BP Mix of Toxins Soaked Up by Wet Skin : Discovery News
- USF scientists confirm underwater plumes came from BP spill - Tampa Bay Times
- Submerged oil plumes suggest gulf spill is worse than BP claims | Environment | The Guardian
- Three years after BP oil spill, USF research finds massive die-off | Tampa Bay Times
- BP Oil Spill Cleanup Workers Are At Higher Risk Of Sickness, Cancer | ThinkProgress
- Environmental Protection Agency, NCP Product Schedule, Accessed May 16, 2010
- Environmental Protection Agency, NCP Product Schedule, Accessed May 16, 2010
- Michael J. Hemmer, Mace G. Barron, and Richard M. Greene (June 30, 2010). "Comparative Toxicity of Eight Oil Dispersant Products on Two Gulf of Mexico Aquatic Test Species". Retrieved August 30, 2011.
- Did BP's oil-dissolving chemical make the spill worse? | HeraldTribune.com
- Numerical study suggests subsea injection of chemicals didn't prevent oil from rising to sea surface
- Is Using Dispersants on the BP Gulf Oil Spill Fighting Pollution with Pollution?: Scientific American
- EPA sued over chemical dispersants used in BP oil spill, 2 years later | abc7news.com
- Groups sue EPA, Coast Guard over dispersants use - San Jose Mercury News
- Judge tosses claims against dispersant maker | The Advertiser | theadvertiser.com
- EPA Whistleblower Accuses Agency of Covering Up Effects of Dispersant in BP Oil Spill Cleanup
- Experts: Health Hazards in Gulf Warrant Evacuations
- "Riki Ott: An Open Letter to US EPA, Region 6". Huffington Post. Retrieved 2010-09-05.
- US points to 'gross negligence' by BP - Americas - Al Jazeera English
- Hertsgaard, Mark (April 22, 2013). "What BP Doesn’t Want You to Know About the 2010 Gulf Spill". Newsweek. The Daily Beast.
- "Crude Solution" Australian 60 Minutes (August 18, 2013) on the health effects of Corexit
- "The 'mess' that oil made" Al Jazeera Inside Story on BP's use of Corexit during the Deepwater Horizon oil spill
- EPA Whistleblower Accuses Agency of Covering Up Effects of Dispersant in BP Oil Spill Cleanup - video by Democracy Now!
- TED Talks video on toxicity of Corexit - Susan Shaw