DOVER, Del. -- Environmental regulators are investigating DuPont's handling of wastewater from the destruction of a military nerve agent in studies that the company claims prove it can treat the wastewater safely.

DuPont has proposed treating up to 4 million gallons of hydrolysate, a caustic wastewater, at its Secure Environmental Treatment facility in Deepwater, N.J., at the foot of the Delaware Memorial Bridge. The wastewater would be left over from the planned destruction of more than 1,200 tons of the nerve agent VX at the Army's Newport Chemical Depot in Indiana.

DuPont recently revealed that effluent left over after treatability studies using 25 sample liters of hydrolysate was processed along with other wastewater at the SET facility last year.

Environmental regulators in Delaware and New Jersey said this week they were unaware that effluent from the laboratory studies had been run through the SET, which discharges wastewater into the Delaware River.

"That was not real smart and not a great idea," said John Hughes, secretary of the Delaware Department of Natural Resources and Environmental Control.

Samuel Wolfe, assistant commissioner of the New Jersey Department of Environmental Protection, said officials in his state are trying to figure out exactly what DuPont did.

"We did not hear about this before it happened," Wolfe said Wednesday.

DuPont spokesman Anthony Farina did not return several telephone messages Wednesday. He instead issued a prepared statement saying DuPont's actions were safely conducted under its New Jersey permits.

"The samples of wastewater were consumed in the bio-treatability study _ removing the hazardous characteristics of the wastewater _ in both pre-treatment and treatment stages in our labs," the statement said. "The result was a clear, non-toxic effluent."

"The resulting effluent from the study was collected and processed with the daily 15 million gallons of wastewater in the wastewater treatment facility as part of the unique DuPont-patented technology process."

In March, DuPont issued a 350-page report saying the proposed treatment of hydrolysate poses no significant risk to the environment or public health.

The company's findings and claims that it can effectively treat the hydrolysate have been questioned by regulators in New Jersey and Delaware, and by officials with the Delaware River Basin Commission.

Facing opposition by lawmakers and members of the public, DuPont and the Army are now awaiting the results of studies by the federal Centers for Disease Control and the U.S. Environmental Protection Agency.