BP's (BP.L) (BP.N) use of dispersant chemicals on the Gulf of Mexico oil spill is sparking questions from a U.S. congressional panel, which says the company used more of these compounds than the U.S. Environmental Protection Agency had directed. But the EPA indicated in a statement on Sunday that the difference between what the agency directed and what BP and the U.S. Coast Guard achieved is slight... At the heart of the questions is a May 26 directive from EPA Administrator Lisa Jackson and then-on-scene coordinator Admiral Mary Landry, making the use of dispersants a last resort and ordering BP to cut the use of these chemicals... The directive allowed the Coast Guard to grant waivers for the use of more dispersant than the directive stipulated, but said these should be issued in "rare cases."