Dispersants are mixtures of surfactants and solvents that are commonly used to break up floating oil slicks into small droplets, which are submerged underwater. This reduces shoreline accumulation but increases the amount of oil underwater. This also increases the surface area of the oil and, in theory, accelerates the destruction of oil by naturally occurring bacteria. Early products in the line included Corexit 7664 An estimated of chemicals were used in response to the supertanker
SS Torrey Canyon oil spill in the United Kingdom in 1967
. The incident harmed marine life and triggered the first significant international public discussions about chemical dispersants' toxicity including the costs and benefits of its deployment.
1968–1988 In April 1968, 300 barrels of Corexit were shipped to the scene of the stricken tanker
Esso Essen off the African coast. 125 barrels of it was sprayed onto the slick by aircraft over two days, after which the slick was dispersed. Corexit was later used in response to the sinking of the Greek tanker
Andron off the west African coast. Corexit 7664's point of difference was described by research chemist Dr Edward Corino to be its water base, where previous dispersants had been hydrocarbon-based and highly toxic. James Avery, Humble Oil and Refining Company's public relations representative for the eastern region confirmed that following the
Torrey Canyon oil spill, another spill in the
Fore River from a tanker en route to
Weymouth, south of
Boston hastened Corexit 7664's development. In February 1969, following application tests in
Montreal, Quebec, Canada, the
Imperial Oil company announced that it had equipped its fleet of tankers and barges with Corexit for the purpose of dispersing oil spills. In February 1970, Corexit was deployed by aircraft onto an oil slick leaking from the stricken tanker
Arrow in
Nova Scotia, Canada. A month later,
Chevron used Corexit and another chemical dispersant called Cold Clean on and beneath an oil platform off the Louisiana coast during a spill in the Gulf of Mexico. Corexit 9527 was applied to spilled oil in
Galveston, Texas in August 1984 but was said to have failed. of Corexit was air-dropped onto oil which leaked from the SS
Puerto Rican as it sank off
San Francisco later that year.
1989–2015 Corexit 9580 was used during the 1989
Exxon Valdez oil spill disaster in Alaska. Corexit 7764 and Corexit 9527 were both used during the 1992
Port Bonython oil spill in
South Australia. 45,000 litres of Corexit 9500 and 9527 were used in the response to the
Montara oil spill off Australia's north-west shelf in 2009 and 2,000 litres of Corexit 9527 were used after the Chinese bulk carrier
Shen Neng was grounded on Australia's
Great Barrier Reef in 2010. Corexit EC9500A and Corexit EC9527A were used during the 2010
Deepwater Horizon oil spill. More recently, Corexit has been used in
Trinidad. In July 2014, a video released by
Anonymous alleged that Corexit 9500 had been used in response to the
Petrotrin oil spill, where 8,000 barrels of oil leaked into the
Guaracara River. The President of
Petrotrin, Khalid Hassanali denied this claim but confirmed that Corexit had been used one mile off-shore near
Pointe-à-Pierre. The use of Corexit is approved in the US by the
U.S. Environmental Protection Agency (EPA).