Citing worries about a fragile coastal environment, the federal Environmental Protection Agency on Thursday gave the giant energy company BP 24 hours to select a less toxic chemical than the one that it is now using to break up crude oil gushing from a ruined well in the Gulf of Mexico.
After submitting a list of one or more alternatives to the agency, the company would then have 72 hours to start using one of them.
In seeking to break up the oil bubbling to the surface from the Deepwater Horizon well, BP has sprayed nearly 700,000 gallons of Corexit chemical dispersants on the surface of the gulf and directly onto the leaking well head, a mile underwater. It is by far the largest use of chemicals to break up an oil spill in United States waters to date.
But scientists and politicians have increasingly questioned why the E.P.A. is allowing use of the Corexit products when less toxic alternatives are available.