Toxic Oil Dispersant Used in Gulf Despite Better Alternative http://www.wired.com/wiredscience/2010/05/gulf-dispersants/

The decision has been a controversial one. A few scientists think dispersants are mostly useful as public relations strategy, as they make the oil slick invisible, even though oil particles continue to do damage. Others consider Corexit the lesser of two evils: It’s known to be highly toxic, adding to the harm caused by oil, but at least it will concentrate damage at sea, sparing sensitive and highly productive coastal areas. Better to sacrifice the deep sea than the shorelines.

Not only did Corexit do a worse job of dispersing oil, but it was three times as lethal to silverfish – used as a benchmark organism in toxicity testing — and more than twice as lethal to shrimp, another benchmark organism and an important part of Gulf fisheries.