Chemical dispersants were sprayed in unprecedented quantities in the Gulf as part of the response to the BP oil spill. The toxic effects of these dispersants on marine life and humans provide yet another illustration of the dangerous environmental impacts of offshore oil drilling and why it must be stopped.
What are dispersants and why are they used in oil-spill response?
Dispersants are chemicals that are sprayed on a surface oil slick to break down the oil into smaller droplets that more readily mix with the water. Dispersants do not reduce the amount of oil entering the environment, but push the effects of the spill underwater. While dispersants make the oil spill less visible, dispersants and dispersed oil under the ocean surface are hazardous for marine life.
Dispersants were being used in the BP oil spill to reduce the chance that the surface oil slick would reach shoreline habitats like marshes and mangroves or come into contact with animals at the surface. However, by mixing the oil below the water surface, dispersants increase the exposure of a wide array of marine life in the water and on the ocean floor to the spilled oil. Dispersants also decrease the ability to skim or absorb oil from the ocean surface.
How much dispersant was used in the BP spill?
More dispersant was used on the BP spill than in any other oil spill in U.S. history. Moreover, for the first time ever, the EPA approved using dispersants not only at the surface but deep underwater at the source of the spill. Approximately 1.84 million gallons of dispersant were applied, with more than 1 million gallons on the surface and 771,000 gallons pumped deep into the water column to dilute the oil.
What are the environmental hazards of dispersants?
Dispersants and dispersed oil have been shown to have significant negative impacts on marine life ranging from fish to corals to birds. Dispersants release toxic break-down products from oil that, alone or in combination with oil droplets and dispersant chemicals, can make dispersed oil more harmful to marine life than untreated oil. Both the short-term and long-term impacts of dispersants on marine life have not been adequately tested. As acknowledged by the EPA, the “long term effects [of dispersants] on aquatic life are unknown.”
Risks to humans
Dispersants pose significant human health risks as well. One of the dispersants used at the BP spill, Corexit 9527A, contains the toxin 2-Butoxyethanol which “may cause injury to red blood cells (hemolysis), kidney or the liver” with “repeated or excessive exposure,” according to the manufacturer’s safety data sheet. Corexit 9527 was sprayed on the 11-million gallon oil slick created by the Exxon Valdez spill, and cleanup workers reportedly suffered health problems afterward, including blood in their urine as well as kidney and liver disorders, attributed to 2-Butoxyethanol.
What dispersants were used? Why weren’t the least toxic, most effective dispersants used?
Although approved by the EPA, formulations of Corexit 9500 and 9527 were banned from use in the United Kingdom in 1998 because laboratory tests found them harmful to marine life that inhabits rocky shores.
BP’s use of the more toxic, less effective Corexit dispersants is under scrutiny since the company that manufactures these dispersants, Nalco Co., has ties to the oil industry. In the 1990s, Nalco formed a joint venture company with Exxon Chemical Company and has board members and executives that have previously worked for Exxon and BP. Nalco has sold millions of dollars of dispersants for the BP spill. Nalco has also refused to disclose all of the ingredients in the Corexit products.
In the first 30 days of the spill, the EPA did not intervene in BP’s decision to use the more toxic, less effective dispersants in the spill. The EPA stated that it approves a list of dispersants, and oil companies are allowed to choose which dispersants to use. On May 20 the EPA issued a directive requiring BP to identify and use a less toxic and more effective dispersant. BP refused in a clash with the federal government, but slowed the use of dispersants shortly thereafter.
Are the giant, deep-sea oil plumes in the Gulf of Mexico related to the use of dispersants?
Researchers working in the BP spill zone discovered giant plumes of oil in the deep waters of the Gulf of Mexico, estimated in size at 10 to 15 miles long and four to five miles wide. The plumes raised concerns about the subsea use of dispersants, but researchers were unable to conclusively determine if they were related. Learn more from The New York Times and Reuters.
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