OIL DISPERSANTS AND WILDLIFE 



Peter H. Albers 



Patuxent Wildlife Research Center 



U.S. Fish and Wildlife Service 



Laurel, Maryland 



Chemical oil dispersants are used routinely throughout the world. The 

 most notable exception is in the United States which has discouraged their 

 use. The improper use of large amounts of highly toxic dispersants at the 

 wreck of the Torrey Canyon in 1968 (Smith 1968) was largely responsible for 

 this cautious attitude toward oil dispersants. Field testing of chemical 

 dispersants in the territorial waters of the United States began in September 

 1978, with tests off the coast of southern California sponsored by the 

 American Petroleum Institute and the Southern California Petroleum Contingency 

 Organization (Smith and Holliday 1979). The tests were designed to evaluate 

 dispersant effectiveness, application procedures, and effects of chemically 

 dispersed oil on marine organisms. The U.S. Environmental Protection Agency 

 (EPA) has approved several dispersants for use in the United States when 

 necessary. This approval means that oil spill response coordinators may be 

 confronted with an increasing number of proposals to use chemicals to dis- 

 perse oil . 



GENERAL INFORMATION 



Oil dispersants are manufactured by many chemical companies and marketed 

 under trade names that do not describe the chemical composition or the appro- 

 priate uses (open sea, beach, method of application). The manufacturer may 

 make specific recommendations about application methods, but information about 

 effectiveness should be obtained from testing laboratories such as the Warren 

 Springs Laboratory in England or regulatory agencies such as the EPA. Oil 

 dispersants are referred to as either "conventional" or "concentrated." The 

 conventional type consists of a surfactant, hydrocarbon solvent, and a chemi- 

 cal stabilizer. New conventional dispersants have less aromatic hydrocarbons 

 in the solvent and the surfactant is more biodegradeable than the older types 

 (Swedmark et al. 1973). Concentrated dispersants are a mixture of several 

 surfactants and small amounts (5 to 10 percent) of additives which serve to 

 stabilize the surfactant mixture, inhibit rust, etc. (Margaret Walsh, per- 

 sonal communication). 



Oil dispersants can be applied from aircraft, boats, or by the use of 

 portable sprayers. Conventional dispersants and some concentrated disper- 

 sants require mixing after the dispersant is sprayed on the oil slick. This 

 is usually accomplished by a boat, by objects tethered behind a boat, or by 

 high pressure water spray. Concentrated dispersants classified as "self- 

 mixing" (e.g., Exxon Corexit 9527) require no additional mixing. Self-mixing 



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