"BP said in its letter--which was signed by Chief Operating Officer Doug Suttles and addressed to the EPA and Coast Guard--that Corexit was the only dispersant that was available in sufficient quantities at the time of the spill. BP also noted that Corexit was 55% to 63% effective in dispersing samples of South Louisiana Crude, similar to the effectiveness of another dispersant, Sea Brat #4. However, BP said it and the manufacturer of Sea Brat #4, Alabaster Corp. of Pasadena, Texas, haven't had time to evaluate important criteria such as whether a small faction of Sea Brat #4 could degrade to nonylphenol, an organic chemical that is toxic to aquatic life.
Corexit doesn't have chemicals that will degrade to nonylphenol and doesn't persist in the environment, BP said. "These qualities make Corexit a better choice for subsea application, based on the information currently available. Corexit appears to have fewer long term effects than the other dispersants evaluated," BP said.



http://www.easybourse.com/bourse/international/news/837292/bp-defends-choice-of-dispersant-after-epa-orders-it-changed.html