Corexit (often styled COREXIT) is a product line of oil dispersants used during oil spill response operations. It is produced by Nalco Holding Company, an indirect subsidiary of Ecolab. Corexit was originally developed by the Standard Oil Company of New Jersey. Corexit is typically applied by aerial spraying or spraying from ships directly onto an oil slick. On contact with the dispersant, oil that would otherwise float on the surface of the water is emulsified into tiny droplets and sinks or (in the unusual case of sub-surface application) remains suspended in the water. In theory this allows the oil to be more rapidly degraded by bacteria (bioremediation) and prevents it from accumulating on beaches and in marshes.Davies, L.; Daniel, F.; Swannell, R.; Braddock, J. Biodegradability of Chemically-dispersed Oil. Report produced for the Minerals Management Service (MMS), Alaska Department of Environmental Conservation (ADEC) and the United States Coast Guard (USCG). March 2001. http://dec.alaska.gov/spar/perp/r_d/aeat.pdf (accessed May 7, 2012)
Corexit was used in unprecedented quantities during the 2010 Deepwater Horizon oil spill in the Gulf of Mexico and became the largest use of such chemicals in the United States. In addition to spraying the dispersant onto the surface slick, it was used in an untested, off-label manner when BP injected it at the broken well-head, roughly below the surface. Researchers continue to examine the effects and effectiveness of Corexit. Studies have so far indicated that the dispersant is toxic to marine life. Corexit has been shown to exert a synergistic effect when mixed with oil, increasing its toxicity.
Ownership Corexit was originally developed by the Standard Oil Company of New Jersey (SONJ) also known as Esso (phonetically derived from the acronym SO). The company later merged with Humble Oil to form Exxon, which is now part of ExxonMobil.
In 2011, Corexit became the property of Ecolab, following a merger between Ecolab and Nalco Holding Company. As of 2015, Corexit is owned by Ecolab and is manufactured by Nalco Company, an indirect subsidiary of Ecolab.
Use
Dispersants are mixtures of surfactants and solvents that are commonly used to break up floating oil slicks into small droplets, which are submerged underwater. This reduces shoreline accumulation but increases the amount of oil underwater. This also increases the surface area of the oil and, in theory, accelerates the destruction of oil by naturally occurring bacteria. Dispersants are themselves a form of pollution that can be toxic to marine life, and the increased activity of bacteria from their presence can deplete oxygen in nearby waters, causing further harm to marine life. There are important trade-offs that must be considered in their use, such as the relative level of toxicity of the dispersant versus the relative toxicity of the spilled oil, to ensure that dispersant use mitigates an oil spill rather than making the problem worse.Is Using Dispersants on the BP Gulf Oil Spill Fighting Pollution with Pollution? Scientific American. Biello, 2010
Corexit products have been used in oil spill response activities since the late 1960s. Early products in the line included Corexit 7664 and Corexit 8666. Corexit 9527 is one of the first modern concentrate dispersants and has been in use since the mid 1970s. Corexit 9500 was designed to replace Corexit 9527. In 2002, Corexit 9527 and Corexit 9500 were the only two chemical dispersants stockpiled in large quantities in the U.S.A.
An estimated of chemicals were used in response to the supertanker SS Torrey Canyon oil spill in the United Kingdom in 1967. The incident harmed marine life and triggered the first significant international public discussions about chemical dispersants' toxicity including the costs and benefits of its deployment.
1968–1988 In April 1968, 300 barrels of Corexit were shipped to the scene of the stricken tanker Esso Essen off the African coast. 125 barrels of it was sprayed onto the slick by aircraft over two days, after which the slick was dispersed. Corexit was later used in response to the sinking of the Greek tanker Andron off the west African coast. Following these events, Humble Oil and Refining Co. and the Enjay Chemical Company (a subsidiary of the Standard Oil Company of New Jersey) each announced the development of Corexit 7664, describing it as non-toxic to marine life- even to shrimp at concentrations of 1% per volume of seawater. Ecotoxicological studies had been undertaken by the Institute of Marine Science at the University of Miami. Corexit 7664's point of difference was described by research chemist Dr Edward Corino to be its water base, where previous dispersants had been hydrocarbon-based and highly toxic. James Avery, Humble Oil and Refining Company's public relations representative for the eastern region confirmed that following the Torrey Canyon oil spill, another spill in the Fore River from a tanker en route to Weymouth, south of Boston hastened Corexit 7664's development.
In February 1969, following application tests in Montreal, Quebec, Canada, the Imperial Oil company announced that it had equipped its fleet of tankers and barges with Corexit for the purpose of dispersing oil spills.
In February 1970, Corexit was deployed by aircraft onto an oil slick leaking from the stricken tanker Arrow in Nova Scotia, Canada. A month later, Chevron used Corexit and another chemical dispersant called Cold Clean on and beneath an oil platform off the Louisiana coast during a spill in the Gulf of Mexico. Corexit 9527 was applied to spilled oil in Galveston, Texas in August 1984 but was said to have failed. of Corexit was air-dropped onto oil which leaked from the SS Puerto Rican as it sank off San Francisco later that year.
1989–2015 Corexit 9580 was used during the 1989 Exxon Valdez oil spill disaster in Alaska. Corexit 7764 and Corexit 9527 were both used during the 1992 Port Bonython oil spill in South Australia.Page J. R. "Report on the oil spill from the tanker "Era" at Port Bonython and on the pollution response operations – Report No: DMH 1594/92" The South Australian State Committee of the National Plan to Combat Pollution of the Sea by Oil, South Australia (1992). 45,000 litres of Corexit 9500 and 9527 were used in the response to the Montara oil spill off Australia's north-west shelf in 2009 and 2,000 litres of Corexit 9527 were used after the Chinese bulk carrier Shen Neng was grounded on Australia's Great Barrier Reef in 2010. Corexit EC9500A and Corexit EC9527A were used during the 2010 Deepwater Horizon oil spill.
More recently, Corexit has been used in Trinidad. In July 2014, a video released by Anonymous alleged that Corexit 9500 had been used in response to the Petrotrin oil spill, where 8,000 barrels of oil leaked into the Guaracara River. The President of Petrotrin, Khalid Hassanali denied this claim but confirmed that Corexit had been used one mile off-shore near Pointe-à-Pierre.
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: Deadly Dispersant in Oil Spill Cleanup – Government Accountability Project
Of the eight European countries in the Bonn Agreement, France, Germany, and the Netherlands have provisions to use Corexit 9500 in an oil spill. Belgium and Norway do not have lists of approved dispersants, but Belgium has a stockpile of Corexit 9527. The UK and Denmark keep lists of approved dispersants and have not approved of Corexit. Sweden does not use dispersant at all.
Deepwater Horizon oil spill Approximately one week following the incident, subsidiaries of BP formally requested Nalco Company (an indirect subsidiary of Nalco Holding Company) to supply large quantities of Corexit 9500. Corexit 9500 was listed on the U.S. EPA National Contingency Plan Product Schedule and authority and direction for its use was provided by responding federal agencies. Nalco immediately provided available quantities of Corexit and increased production to supply the product to BP's subsidiaries.
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. BP's response to dispersant alternatives was judged to be deficient by both the EPA and the US Coast Guard, requiring EPA to perform its own analysis on the relative toxicity of dispersants. Their peer-reviewed conclusions on August 2, 2010 found that Corexit 9500A was generally neither more nor less toxic than the other available dispersants, and that dispersant-oil mixtures were not generally more nor less toxic to test species than oil alone. 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 per day. After May 26 daily average use decreased 9%, an average of slightly more than per day.
On July 15, 2010, BP announced that it had capped the leaking well, and the application of dispersants by the response effort ceased shortly thereafter.
The total used in the event was of Corexit EC9500A and Corexit EC9527A, with roughly 58% sprayed from the air.What BP Doesn't Want You to Know About the 2010 Gulf Spill – Newsweek and The Daily Beast
Composition and Occupational Health Hazards
Corexit 9527 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".
Corexit 9500 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.
Toxicity
Corexit is banned in the United Kingdom due to concerns about possible adverse health effects on people using it.