Eighteen top laboratory officials were later fired, demoted or transferred.

While uncovering many problems with the thesis, the teams were unable to lay it to rest, laboratory officials say.

The department said its personnel and laboratory officials had acted responsibly.

The contaminants have reached as far as 230 feet down, laboratory officials said.

Neither worker was exposed to serious amounts of radiation, laboratory officials said.

Investigators have also found toxic chemicals in the water, though laboratory officials assert that their center is not the source, according to the study.

Over the years, researchers had added more Plexiglas, which increased the fuel available for a fire, laboratory officials said today.

The Administration official took exception to the testimony by the laboratory officials.

"We had very tight controls on access," a laboratory official said.

Dr. Lee's trip was taken with the approval of laboratory officials.