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.