Corexit

Corexit^[1] (often styled COREXIT)^[2] is a product line of oil dispersants used during oil spill response operations. It is produced by Nalco Holding Company, an indirect subsidiary of Ecolab.^[3] Corexit was originally developed by the Standard Oil Company of New Jersey.^[4] Corexit is typically applied by aerial spraying or spraying from ships directly onto an oil slick. On contact with the dispersant, oil that would otherwise float on the surface of the water is emulsified into tiny droplets and sinks or (in the unusual case of sub-surface application) remains suspended in the water. In theory this allows the oil to be more rapidly degraded by bacteria (bioremediation) and prevents it from accumulating on beaches and in marshes.^[5][6][7]

Corexit was used in unprecedented quantities during the 2010 Deepwater Horizon oil spill in the Gulf of Mexico^[8] and became the largest use of such chemicals in the United States.^[9] In addition to spraying the dispersant onto the surface slick, it was used in an untested, off-label manner when BP injected it at the broken well-head, roughly 1,500 m (5,000 ft) below the surface.^[10] Researchers continue to examine the effects and effectiveness of Corexit. Studies have so far indicated that the dispersant is toxic to marine life.^[11] Corexit has been shown to exert a synergistic effect when mixed with oil, increasing its toxicity.^[12]