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Corexit is a product line of solvents produced by Nalco Holding Company.

Contents

[hide]

[edit] Use

One variant was used in the 1989 Exxon Valdez disaster in Alaska. In 2010, Corexit EC9500A and Corexit EC9527A were used in unprecedentedly large quantities in the Deepwater Horizon oil spill.[1] On May 19, 2010 the Environmental Protection Agency 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[2], and begin applying them within 72 hours of EPA approval of their choices.[3] BP has used Corexit 9500A and Corexit 9527A thus far, applying 800,000 US gallons (3,000,000 l) total[4], including the company’s estimate of 55,000 US gallons (210,000 l) underwater.[5]

[edit] Composition

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 sulfonic acid salt with a small concentration of propylene glycol.[6][7] Corexit EC9500A is mainly comprised of hydrotreated light petroleum distillates, propylene glycol and a proprietary organic sulfonic acid salt.[8] Propylene glycol is a chemical commonly used as a solvent or moisturizer in pharmaceuticals and cosmetics. An organic sulfonic acid salt is a synthetic chemical detergent, such as dodecyl benzene sulfonate used in laundry detergents, that acts as a surfactant to emulsify oil and allow its dispersion into water.

[edit] 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 but is dispersed in three.

Corexit EC9500A (formerly called Corexit 9500) was 54.7% effective in handling Louisiana crude, while Corexit EC9527A was 63.4% effective in handling the same oil.[9][10]

[edit] Toxicity and alternatives

The safety data sheet states “The potential human hazard is: High.”

According to the Alaska Community Action on Toxics, the use of Corexit during the Exxon Valdez oil spill caused “respiratory, nervous system, liver, kidney and blood disorders” in people.[
7]
According to the EPA, Corexit is more toxic than dispersants made by several competitors and less effective in handling southern Louisiana crude.[11] However, the oil from Deepwater Horizon is not believed to be typical Louisiana crude.

Reportedly Corexit is toxic to marine life and helps keep spilled oil submerged. The quantities used in the Gulf will create ‘unprecedented underwater damage to organisms.’[12] 9527A is also hazardous for humans: ‘May cause injury to red blood cells (hemolysis), kidney or the liver’.[13]

Alternative dispersants which are approved by the EPA are listed on the National Contingency Plan Product Schedule[14] and rated for their toxicity and effectiveness.[15]

[edit] See also

[edit] References

  1. ^ New York Times, “less toxic dispersants lose out in BP oil spill cleanup”, May 13, 2010
  2. ^ “National Contingency Plan Product Schedule”. Environmental Protection Agency. 2010-05-13. http://www.epa.gov/emergencies/content/ncp/product_schedule.htm. Retrieved 2010-05-21. 
  3. ^ “Dispersant Monitoring and Assessment Directive – Addendum”. Environmental Protection Agency. 2010-05-20. 
  4. ^ Paul Quinlan (2010-05-24). “Secret Formulas, Data Shortages Fuel Arguments Over Dispersants Used for Gulf Spill”. New York Times. http://www.nytimes.com/gwire/2010/05/24/24greenwire-secret-formulas-data-shortages-fuel-arguments-o-9112.html. Retrieved 2010-05-24. 
  5. ^ Juliet Eilperin (2010-05-20). “Post Carbon: EPA demands less-toxic dispersant”. Washington Post. http://views.washingtonpost.com/climate-change/post-carbon/2010/05/epa_demands_less_toxic_dispersant.html. Retrieved 2010-05-20. 
  6. ^ “Safety Data Sheet Product Corexit® EC9527A”. http://www.deepwaterhorizonresponse.com/posted/2931/Corexit_EC9527A_MSDS.539295.pdf. Retrieved 2010-05-16. 
  7. ^ a b “Chemicals Meant To Break Up BP Oil Spill Present New Environmental Concerns”. ProPublica. http://www.propublica.org/article/bp-gulf-oil-spill-dispersants-0430. Retrieved 2010-05-07. 
  8. ^ “Safety Data Sheet Product Corexit® EC9500A”. http://www.deepwaterhorizonresponse.com/posted/2931/Corexit_EC9500A_MSDS.539287.pdf. Retrieved 2010-05-16. 
  9. ^ Environmental Protection Agency, NCP Product Schedule, Accessed May 16, 2010, http://www.epa.gov/swercepp/web/content/ncp/products/corex950.htm
  10. ^ Environmental Protection Agency, NCP Product Schedule, Accessed May 16, 2010, http://www.epa.gov/swercepp/web/content/ncp/products/corex952.htm
  11. ^ New York Times, May 13, 2010, Less toxic dispersants lose out in bp oil spill cleanup, http://www.nytimes.com/gwire/2010/05/13/13greenwire-less-toxic-dispersants-lose-out-in-bp-oil-spil-81183.html
  12. ^ Dugan, Emily (0 May 2010). “Oil spill creates huge undersea ‘dead zones'”. The Independent. http://www.independent.co.uk/news/world/americas/oil-spill-creates-huge-undersea-dead-zones-1987039.html. Retrieved 30 May 2010. 
  13. ^ “Material Safety Data Sheet: Corexit EC9527A”. NALCO. 5/11/2010. http://www.piersystem.com/posted/2931/Corexit_EC9527A_MSDS.539295.pdf. Retrieved 30 May 2010. 
  14. ^ “National Contingency Plan Product Schedule”. Environmental Protection Agency. 2010-05-13. http://www.epa.gov/emergencies/content/ncp/product_schedule.htm. Retrieved 2010-05-21. 
  15. ^ “National Contingency Plan Product Schedule Toxicity and Effectiveness Summaries”. Environmental Protection Agency. 2010-05-13. http://www.epa.gov/emergencies/content/ncp/tox_tables.htm#dispersants. Retrieved 2010-05-21. 

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