Despite an order issued by the Obama administration to curb the use of harsh dispersants, which work like soap on kitchen grease to break up oil in the water and make it easier for microbes to digest, the Coast Guard has approved every appeal BP’s made to use them. According to a report issued by the office of Rep. Edward Markey of Massachusetts, the Coast Guard granted BP's requests 74 times over 59 days. "BP carpet bombed the ocean with these chemicals, and the Coast Guard allowed them to do it," Markey said in a statement. Though an investigation into the environmental effects of dispersants began after they were used to clean up the Exxon Valdez spill in 1989, it faltered as the spill was forgotten, and the environmental impact of the chemicals is still unknown. Retired Admiral Thad Allen, who's heading the government response to the spill, defended the Coast Guard's approval of dispersants, insisting their total use declined after the administration's May 26 order, and that the decision to use them was a "tactical" one, made by people on the scene. "Sometimes there was no other way to attack the oil than to use dispersants," he said, adding, "I'm satisfied we only use them when they are needed."