The Disperant Low Down

Critics say Nalco, which formed a joint venture company with Exxon Chemical in 1994, boasts oil-industry insiders on its board of directors and among its executives, including an 11-year board member at BP and a top Exxon executive who spent 43 years with the oil giant.

"It's a chemical that the oil industry makes to sell to itself, basically," said Richard Charter, a senior policy adviser for Defenders of Wildlife.

The older of the two Corexit products that BP has used in the Gulf spill, Corexit 9527, was also sprayed in 1989 on the 11-million-gallon slick created by the Exxon Valdez grounding in Alaska's Prince William Sound. Cleanup workers suffered health problems afterward, including blood in their urine and assorted kidney and liver disorders. Some health problems were blamed on the chemical 2-butoxyethanol, an ingredient discontinued in the latest version of Corexit, Corexit 9500, whose production Nalco officials say has been ramped up in response to the Gulf of Mexico disaster. Among Corexit's competitors, a product called Dispersit far outpaced Corexit 9500, EPA test results show, rating nearly twice as effective and between half and a third as toxic, based on two tests performed on fish and shrimp.