The manufacturer of the oil-dispersing chemicals being used by BP PLC in the Gulf of Mexico said that injecting the dispersant on a still-gushing wellhead was unprecedented and should be carried out with ample testing.

"That's a new approach," said Erik Fyrwald, CEO of Nalco, whose dispersants are marketed under the name Corexit. "Our belief is, because it is a new approach, it needs to be done with a lot of testing to make sure there are no unfavorable impacts, and we encourage that."

Scientists have compared BP's heavy use of dispersants in the Gulf to a massive chemistry and biology experiment.