What is Corexit?

Corexit is a product line of solvents 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Corexit was the most-used dispersant in the Deepwater Horizon oil spill in the Gulf of Mexico, with COREXIT 9527 having been replaced by COREXIT 9500 after the former was deemed too toxic.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.