Feds approve use of underwater dispersants for oil spill

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.