Mobile-area scientists warned BP PLC officials and Coast Guard Adm. Thad Allen a week ago that the use of dispersants both on the surface and underwater

could have grave consequences for the Gulf ecosystem.

The scientists, Bob Shipp of the University of South Alabama and George Crozier of the Dauphin Island Sea Lab, said they felt their concerns were ignored at the time.

BP did not respond to the Press-Register's questions.

Dispersants have been used -- mostly in surface applications -- almost every day since the Deepwater Horizon rig exploded on April 20, killing 11 people and starting the massive spill.

problems foreseen

U.S. Coast Guard officials have apparently known for years that there could be significant problems in the federal and industry response to a major oil spill.

The report that followed a 2004 "Spill of National Significance" training exercise concluded, "Oil spill response personnel did not appear to have even a basic knowledge of the equipment required to support salvage or spill clean up operations."

It continued, "as a result, some issues and complex processes unique to spill response were not effectively addressed."

Read the complete story: Coast Guard officials told of potential oil spill response problems years ago

Thursday, the U.S. Environmental Protection Agency, which approved the use of more than 655,000 gallons of dispersant chemicals so far, announced that the chemical in use for the last month was too toxic. BP was ordered to find another dispersant by midnight Thursday.

Dispersant chemicals are used to break oil into tiny drops that become suspended in the water column. At least some of the water quality testing recently conducted by the EPA around the spill site suggests dispersed oil may have begun to impact oxygen levels in the water.

About 600,000 gallons of Corexit dispersant has been applied to oil floating on the Gulf's surface. Another 55,000 gallons has been applied underwater, according to federal officials, with most of the underwater application coming in the last week.

Federal officials approved the underwater use before conducting basic environmental tests, Crozier said.

Data sheets with ecological information about the Corexit dispersant include this statement: "No toxicity studies have been conducted on this product."

Crozier said Wednesday that he and other scientists were contacted a week earlier by a BP official who wanted to discuss underwater dispersant use.

That official told him that BP would start a testing program Saturday, Crozier said.

EPA and the U.S. Coast Guard approved the increased use of underwater dispersant the day before the testing was to begin.

"How could that have happened before they'd even conducted any of the testing they told me about?" said Crozier. "I'm losing faith in the system."

Crozier said it was clear to him in his conversation with the BP scientist that using dispersant underwater was a forgone conclusion and that the BP scientist was not interested in Crozier's scientific opinion.

"He spent the first five minutes lecturing me about the dispersant toxicity. I told him I wasn't worried about that. I was worried about the toxicity of the dispersed oil. He didn't want to address that," Crozier said.

Shipp, head of the University of South Alabama's marine sciences department and president of the federal Gulf of Mexico Fishery Management Council, said the BP scientists he spoke with "were not listening to us at all."

Shipp and Crozier both identified the BP representative as Peter Carragher, a company vice president and scientist. Both said they were unsure of the spelling of the man's last name.

The Press-Register found a short online biography for Peter Carragher, head of discipline for exploration, on BP's website. The biography described Carragher as a geologist.

"He was lecturing me on my lack of knowledge about the marine environment. I told him we were most concerned about the oil getting in the food web if they sink it with dispersants," Shipp said. "When we started talking about the sediments and the food web, they turned off. They were all about chemical reactions and that sort of thing. They just kept saying, 'EPA approved it.'"

Some of the data released by the EPA on Thursday indicates that oxygen levels in the area around the spill were on the threshold of being too low to support life. Subsequent data collected with a different type of instrument indicated that oxygen levels were fine, according to the agency.

The scientists said that when the oil was allowed to come to the surface, many of the most toxic components -- hexane, benzene, other volatile gases -- were evaporating. But when the oil is trapped underwater through the use of dispersants, those toxic chemicals also are trapped in the water.

Plus, the breakdown of the oil by aquatic microbes robs the water of oxygen.

"The concerns about a hypoxic (low-oxygen) issue are very real," Crozier said. "Whether it happens, how fast it happens, I can't predict, but the idea of that much microbial activity using oxygen, that is totally predictable."

Crozier said he fears that a decision was made to protect beaches in the short term at the risk of jeopardizing the long-term health of the Gulf.