An oil dispersant breaks the oil up into globules that get eaten up by microbes or sink into the water column before hitting the shore. Dispersing the oil is one way to protect birds and other wildlife and keep the oil slick from making landfall.
BP is currently using toxic Corexit dispersant chemicals such as Corexit 9500 and Corexit 9527 to disperse the oil in the Gulf of Mexico. There is not much known about the chemical composition of these Corexit dispersants. The makeup of the dispersant is often kept a secret under various trade laws, however, if you search for it in the Materials Safety Data Sheet (MSDS), you can get an idea about the nature of the dispersant as well as any health hazards. According to MSDS, Corexit 9527 is a mixture of chemicals, primarily 2-Butoxyethanol, which can be toxic - “…ABSORPTION MAY CAUSE HEMOLYTIC ANEMIA & KIDNEY DAMAGE…” and hence can become highly toxic to coral reefs. For more information, click here.
A Material Safety Data Sheet (MSDS) is a document that contains information on the potential health effects of exposure to chemicals, or other potentially dangerous substances, and on safe working procedures when handling chemical products. These documents are useful for obtaining information about chemicals used in the laboratory. Go to MSDS and just type in the name of a chemical (e.g., Corexit). For more resources, look in the Chemistry Research Guide under the “Resource” tab and select “Safety.”