Corexit
Encyclopedia
Corexit is a product line of solvent
s primarily used as a dispersant for breaking up oil slicks. It is produced by Nalco Holding Company
which is associated with BP
and Exxon
. Corexit was the most-used dispersant in the Deepwater Horizon oil spill
in the Gulf of Mexico, with COREXIT 9527 having been replaced by COREXIT 9500 after the former was deemed too toxic. Oil that would normally rise to the surface of the water is broken up by the dispersant into small globules that can then remain suspended in the water.
. The Environmental Protection Agency (EPA) had pre-approved both forms of Corexit for uses in emergencies such as the Gulf oil spill. Corexit 9580 was used during the 1989 Exxon Valdez oil spill
disaster in Alaska.
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, citing safety and availability concerns with alternatives. Sea Brat 4, the only effective alternative that is available in quantities large enough for the spill and is less toxic, was rejected by BP because of the risk that components would break down into nonylphenol
, which persists in the environment and is toxic to marine life.
BP had used Corexit EC9500A and Corexit EC9527A by late May, applying 800000 gallons (3,028,329.6 l) total, but more accurate estimates run as high as 1000000 gallons (3,785,412 l) underwater. By late April 2010, Nalco, the maker of Corexit, says that it has been deploying only Corexit 9500.
and a proprietary organic
sulfonate
with a small concentration of propylene glycol
.
, butanedioic acid, and petroleum distillates. Corexit EC9500A is made mainly of hydrotreated
light petroleum distillates, propylene glycol
and a proprietary organic sulfonate
. Environmentalists also pressured Nalco to reveal to the public what concentrations of each chemical are in the product; Nalco considers that information to be a trade secret
, but has shared it with the EPA. Propylene glycol is a chemical commonly used as a solvent or moisturizer in pharmaceuticals and cosmetics, and is of relatively low toxicity. An organic sulfonate (or organic sulfonic acid salt) is a synthetic chemical detergent
, that acts as a surfactant
to emulsify oil and allow its dispersion into water. The identity of the sulfonate used in both forms of Corexit was disclosed to the EPA in June 2010, as dioctyl sodium sulfosuccinate
.
The first analysis of the 57 chemicals found in Corexit formulas 9500 and 9527 was conducted by Earthjustice
and Toxipedia Consulting Services in the summer of 2011. Results showed the dispersant could contain cancer-causing agents, hazardous toxins and endocrine-disrupting chemicals.
Corexit 9527, considered by the EPA to be an acute health hazard, is stated by its manufacturer to be potentially harmful to red blood cell
s, the kidney
s and the liver
, and may irritate eyes and skin. The chemical 2-butoxyethanol, found in Corexit 9527, was identified as having caused lasting health problems in workers involved in the cleanup of the Exxon Valdez oil spill.
According to the Alaska Community Action on Toxics, the use of Corexit during the Exxon Valdez oil spill caused people "respiratory, nervous system, liver, kidney and blood disorders".
Like 9527, 9500 can cause hemolysis
(rupture of blood cells) and may also cause internal bleeding.
According to the EPA, Corexit is more toxic than dispersants made by several competitors and less effective in handling southern Louisiana crude. On May 19, 2010, the EPA ordered BP
to change to a different dispersant than Corexit, or to produce a report within 24 hours on alternatives considered 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 dispersants; 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.
Reportedly Corexit may be toxic to marine life and helps keep spilled oil submerged. There is concern that the quantities used in the Gulf will create 'unprecedented underwater damage to organisms.' 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 9500 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.
in three (in the water).
In handling Louisiana crude Corexit EC9500A (formerly called Corexit 9500) was 54.7% effective, while Corexit EC9527A was 63.4% effective. The EPA lists 12 other types of dispersants as being more effective in dealing with oil in a way that is safe for wildlife. One of those tested was Dispersit
, which was 100% effective in dispersing Gulf oil but is more toxic to inland silverside
and shrimp
than Corexit.
Evidence from researchers at Woods Hole Oceanographic Institute shows 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".
Alternative dispersants which are approved by the EPA are listed on the National Contingency Plan Product Schedule and rated for their toxicity and effectiveness.
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
s primarily used as a dispersant for breaking up oil slicks. It is produced by Nalco Holding Company
Nalco Holding Company
Nalco Holding Company supplies water treatment and process improvement services, chemicals and equipment programs for industrial and institutional markets. These products and services are marketed in some cases to prevent corrosion, contamination and the buildup of harmful deposits...
which is associated with BP
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
and Exxon
Exxon
Exxon is a chain of gas stations as well as a brand of motor fuel and related products by ExxonMobil. From 1972 to 1999, Exxon was the corporate name of the company previously known as Standard Oil Company of New Jersey or Jersey Standard....
. Corexit was the most-used dispersant in the Deepwater Horizon oil spill
Deepwater Horizon oil spill
The Deepwater Horizon oil spill is an oil spill in the Gulf of Mexico which flowed unabated for three months in 2010, and continues to leak fresh oil. It is the largest accidental marine oil spill in the history of the petroleum industry...
in the Gulf of Mexico, with COREXIT 9527 having been replaced by COREXIT 9500 after the former was deemed too toxic. Oil that would normally rise to the surface of the water is broken up by the dispersant into small globules that can then remain suspended in the water.
Use
In 2010, Corexit EC9500A and Corexit EC9527A were used in large quantities in the Deepwater Horizon oil spillDeepwater Horizon oil spill
The Deepwater Horizon oil spill is an oil spill in the Gulf of Mexico which flowed unabated for three months in 2010, and continues to leak fresh oil. It is the largest accidental marine oil spill in the history of the petroleum industry...
. The Environmental Protection Agency (EPA) had pre-approved both forms of Corexit for uses in emergencies such as the Gulf oil spill. Corexit 9580 was used during the 1989 Exxon Valdez oil spill
Exxon Valdez oil spill
The Exxon Valdez oil spill occurred in Prince William Sound, Alaska, on March 24, 1989, when the Exxon Valdez, an oil tanker bound for Long Beach, California, struck Prince William Sound's Bligh Reef and spilled of crude oil. It is considered to be one of the most devastating human-caused...
disaster in Alaska.
On May 19, 2010 the EPA gave BP
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
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
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
could not find an alternative, to provide a report on the alternative dispersants investigated and reasons for their rejection. BP took the latter option, citing safety and availability concerns with alternatives. Sea Brat 4, the only effective alternative that is available in quantities large enough for the spill and is less toxic, was rejected by BP because of the risk that components would break down into nonylphenol
Nonylphenol
Nonylphenol is a family of closely related organic compounds, a subset of the alkylphenols. This collection of compounds is a precursor to commercially important detergents...
, which persists in the environment and is toxic to marine life.
BP had used Corexit EC9500A and Corexit EC9527A by late May, applying 800000 gallons (3,028,329.6 l) total, but more accurate estimates run as high as 1000000 gallons (3,785,412 l) underwater. By late April 2010, Nalco, the maker of Corexit, says that it has been deploying only Corexit 9500.
Corexit 9527
The proprietary composition is not public, but the manufacturer's own safety data sheet on Corexit EC9527A says the main components are 2-butoxyethanol2-Butoxyethanol
2-Butoxyethanol is an organic solvent with the formula BuOC2H4OH . It is a colorless liquid with a sweet, ether-like odour. It is a butyl ether of ethylene glycol...
and a proprietary organic
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
sulfonate
Sulfonate
A sulfonate is a salt or ester of a sulfonic acid. It contains the functional group R-SO2O-.- Sulfonate salts:Anions with the general formula RSO2O− are called sulfonates. They are the conjugate bases of sulfonic acids with formula RSO2OH. As sulfonic acids tend to be strong acids, the...
with a small concentration of propylene glycol
Propylene glycol
Propylene glycol, also called 1,2-propanediol or propane-1,2-diol, is an organic compound with formula C3H8O2 or HO-CH2-CHOH-CH3...
.
Corexit 9500
In response to public pressure, the EPA and Nalco released the list of the six ingredients in Corexit 9500, revealing constituents including sorbitanSorbitan
Sorbitan is a mixture of chemical compounds derived from the dehydration of sorbitol. The mixture can vary, but usually consists of 1,4-anhydrosorbitol, 1,5-anhydrosorbitol and 1,4,3,6-dianhydrosorbitol...
, butanedioic acid, and petroleum distillates. Corexit EC9500A is made mainly of hydrotreated
Hydrodesulfurization
Hydrodesulfurization is a catalytic chemical process widely used to remove sulfur from natural gas and from refined petroleum products such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils...
light petroleum distillates, propylene glycol
Propylene glycol
Propylene glycol, also called 1,2-propanediol or propane-1,2-diol, is an organic compound with formula C3H8O2 or HO-CH2-CHOH-CH3...
and a proprietary organic sulfonate
Sulfonate
A sulfonate is a salt or ester of a sulfonic acid. It contains the functional group R-SO2O-.- Sulfonate salts:Anions with the general formula RSO2O− are called sulfonates. They are the conjugate bases of sulfonic acids with formula RSO2OH. As sulfonic acids tend to be strong acids, the...
. Environmentalists also pressured Nalco to reveal to the public what concentrations of each chemical are in the product; Nalco considers that information to be a trade secret
Trade secret
A trade secret is a formula, practice, process, design, instrument, pattern, or compilation of information which is not generally known or reasonably ascertainable, by which a business can obtain an economic advantage over competitors or customers...
, but has shared it with the EPA. Propylene glycol is a chemical commonly used as a solvent or moisturizer in pharmaceuticals and cosmetics, and is of relatively low toxicity. An organic sulfonate (or organic sulfonic acid salt) is a synthetic chemical detergent
Detergent
A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...
, that acts as a surfactant
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
to emulsify oil and allow its dispersion into water. The identity of the sulfonate used in both forms of Corexit was disclosed to the EPA in June 2010, as dioctyl sodium sulfosuccinate
Dioctyl sodium sulfosuccinate
Dioctyl sodium sulfosuccinate or docusate sodium – often referred to as DSS, Aerosol OT or AOT – is a common ingredient in consumer products, especially laxatives of the stool softener type...
.
Toxicity
The relative toxicity of Corexit and other dispersants are difficult to determine due to a scarcity of scientific data. 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 another 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 products tested are "without toxicity", according to an EPA administrator, and the ecological effect of mixing the dispersants with oil is unknown, as is the toxicity of the breakdown products of the dispersant.The first analysis of the 57 chemicals found in Corexit formulas 9500 and 9527 was conducted by Earthjustice
Earthjustice
Earthjustice is a non-profit public interest law firm based in the United States that specializes in cases protecting natural resources, safeguarding public health, and promoting clean energy...
and Toxipedia Consulting Services in the summer of 2011. Results showed the dispersant could contain cancer-causing agents, hazardous toxins and endocrine-disrupting chemicals.
Corexit 9527, considered by the EPA to be an acute health hazard, is stated by its manufacturer to be potentially harmful to red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s, the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
s and the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
, and may irritate eyes and skin. The chemical 2-butoxyethanol, found in Corexit 9527, was identified as having caused lasting health problems in workers involved in the cleanup of the Exxon Valdez oil spill.
According to the Alaska Community Action on Toxics, the use of Corexit during the Exxon Valdez oil spill caused people "respiratory, nervous system, liver, kidney and blood disorders".
Like 9527, 9500 can cause hemolysis
Hemolysis
Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid...
(rupture of blood cells) and may also cause internal bleeding.
According to the EPA, Corexit is more toxic than dispersants made by several competitors and less effective in handling southern Louisiana crude. On May 19, 2010, the EPA ordered BP
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
to change to a different dispersant than Corexit, or to produce a report within 24 hours on alternatives considered 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 dispersants; 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.
Reportedly Corexit may be toxic to marine life and helps keep spilled oil submerged. There is concern that the quantities used in the Gulf will create 'unprecedented underwater damage to organisms.' 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 9500 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
Material safety data sheet
A Material Safety Data Sheet is a form with data regarding the properties of a particular substance....
, 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.
Effectiveness
The oil film will be dispersed in small droplets which intermix with the seawater. The oil is then not only distributed in two dimensions (on the surface) but is dispersedDispersion (chemistry)
A dispersion is a system in which particles are dispersed in a continuous phase of a different composition . See also emulsion. A dispersion is classified in a number of different ways, including how large the particles are in relation to the particles of the continuous phase, whether or not...
in three (in the water).
In handling Louisiana crude Corexit EC9500A (formerly called Corexit 9500) was 54.7% effective, while Corexit EC9527A was 63.4% effective. The EPA lists 12 other types of dispersants as being more effective in dealing with oil in a way that is safe for wildlife. One of those tested was Dispersit
Dispersit
Dispersit SPC 1000 or Dispersit is a dispersant used for oil spills, produced by U.S. Polychemical Corporation.-Composition:It combines a predominately oil-soluble surfactant with a predominately water-soluble surfactant and a co-solvent for coupling a mixture of the predominately oil-soluble...
, which was 100% effective in dispersing Gulf oil but is more toxic to inland silverside
Inland silverside
The inland silverside, Menidia beryllina, is a neotropical silverside native to eastern North America, and introduced into California. It is a fish of estuaries and freshwater environments....
and shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
than Corexit.
Evidence from researchers at Woods Hole Oceanographic Institute shows 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".
Alternatives
UK authorities have an approved list of products which must pass both "sea/beach" and "rocky shore" laboratory toxicity tests, following a review of approval procedures over a decade ago. Corexit did not pass the rocky shore test when submitted for renewal of its inclusion on the list, and was dropped. Although it has been omitted from the approved list since 1998, existing stocks which pre-date the removal may be permitted for use away from rocky shorelines, subject to prior approval.Alternative dispersants which are approved by the EPA are listed on the National Contingency Plan Product Schedule and rated for their toxicity and effectiveness.
External links
- EPA Whistleblower Accuses Agency of Covering Up Effects of Dispersant in BP Oil Spill Cleanup - video by Democracy Now!Democracy Now!Democracy Now! and its staff have received several journalism awards, including the Gracie Award from American Women in Radio & Television; the George Polk Award for its 1998 radio documentary Drilling and Killing: Chevron and Nigeria's Oil Dictatorship, on the Chevron Corporation and the deaths of...
- video by TED Talks
- Nalco Oil Dispersants Corexit product page
- Aerial Dispersant Delivery System (ADDS Pack) Dosage Rates
- U.S. National Library of Medicine: Hazardous Substances Databank – Corexit 9500 and 9527