Wikipedia
Composition
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-butoxyethanol and a proprietary
organic sulfonate with a small concentration of
propylene glycol.
[15][16]
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.
[3] Corexit EC9500A is mainly comprised of
hydrotreated light petroleum distillates,
propylene glycol and a proprietary organic
sulfonate.
[17] 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.
[18] 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.
[19] Often referred to as docusate sodium, this chemical is the active ingredient in several stool-softener laxatives.
Toxicity
The relative toxicity of Corexit and other dispersants are difficult to determine due to a scarcity of scientific data.
[3] 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."
[20] According to the manufacturer's website, workers applying Corexit should wear breathing protection and work in a ventilated area.
[21] Compared with 12 other dispersants listed by the EPA, Corexit 9500 and 9527 are either similarly toxic or 10 to 20 times more toxic.
[7] 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.
[22] 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.
[22]
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.
[23][14] 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.
[24] 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".
[16] Like 9527, 9500 can cause
hemolysis (rupture of blood cells) and may also cause internal bleeding.
[4]
According to the EPA, Corexit is more toxic than dispersants made by several competitors and less effective in handling southern Louisiana crude.
[25] On May 20, 2010, the EPA ordered
BP to look for less toxic alternatives to Corexit, and later ordered BP to stop spraying dispersants, but BP responded that it thought that Corexit was the best alternative and continued to spray it.
[3]
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.'
[26] 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.
[27] Corexit 9500 causes oil to form into small droplets in the water; fish may be harmed when they eat these droplets.
[4] According to its
Material safety data sheet, Corexit may also
bioaccumulate, remaining in the flesh and building up over time.
[28] Thus predators who eat smaller fish with the toxin in their systems may end up with much higher levels in their flesh.
[4]