New Orleans, Louisiana (CNN) -- The Coast Guard and the Environmental Protection Agency planned a new tactic Saturday against the massive oil leak in the Gulf of Mexico, authorizing BP to use oil dispersants.
Oil dispersants are chemicals that can break the oil down into small drops and prevent it from reaching the surface or the shore. Dispersants are generally less harmful than the oil itself, which is highly toxic, and they biodegrade more quickly, the Coast Guard said.
The decision is an "important step" at reducing potential damage from the spill, because dispersants can be more effective underwater than on the ocean's surface, officials said.
Less dispersant is also needed underwater than once the oil has reached the surface, the Coast Guard said.
"Based on the scientific analysis of the EPA and (National Oceanic and Atmospheric Administration) and review by the National Response Team, it has been determined that the use of dispersants at the subsea source is the prudent and responsible action to take along with other tactics including surface dispersant, skimming, and controlled burns," said Coast Guard Adm. Thad Allen, the national incident commander for the spill.
Underwater use of dispersants could lessen the spill's overall impact, but they're not a "silver bullet," EPA Administrator Lisa Jackson warned.
"They are used to move us towards the lesser of two difficult environmental outcomes," she said in a statement. "Until the flow of oil is stemmed, we must continue to take any responsible action that will reduce the impact of the spill, and that is what we are doing."
BP said it planned another attempt Saturday to cap the leaking well. It will involve inserting a tube into the well's ruptured pipe, collecting oil, then sending it to a vessel on the surface, said Mark Proegler, a BP spokesman.
The company has lowered a smaller containment dome for use if the insertion tube does not stem the flow of oil into the water, Proegler said.
Allen said the containment dome was the first choice, followed by the insertion tube.
Neither procedure would be a permanent solution, Allen said Friday in Mississippi. Both "will reduce the leakage, not stop the leakage," he said.
The ultimate solution, Allen said, will be achieved by relief wells being drilled near the leak site. Those will take weeks, if not months, to complete, BP has said.
Doug Suttles, BP's chief operating officer for exploration and production, said the company has spent more than $450 million responding to the spill and that more than 14,000 people are involved in the effort.
The forecast this weekend and early next week "looks very favorable to use all tools," he said, citing burning, skimming operations and use of surface and subsurface dispersants.
BP has said since the April 20 explosion of the Deepwater Horizon drill rig that about 5,000 barrels -- or 210,000 gallons -- have been pouring out of the well a day. The company says it reached that number using data, satellite images and consultation with the Coast Guard and the National Oceanic and Atmospheric Administration.
A researcher at Purdue University however, said BP's estimate is low and that about 70,000 barrels of oil are leaking each day. Associate Professor Steve Wereley, who works in the mechanical engineering department, said he based the estimate on an analysis of video of the spill.
A BP executive has rejected Wereley's assertion.