The U.S. Army continues to buy, store and transport tons of a highly toxic compound used as a chemical warfare decontaminating agent even though it is too poisonous to use in training, it destroys the equipment it is supposed to clean and safer and less expensive alternatives are available, according to congressional investigators.

Thousands of gallons of the material, known as decontaminating solution 2 or DS-2, are stored in corroding and leaking containers at "grossly" inadequate warehouses in the United States and overseas, the General Accounting Office said in a report released Thursday.

The chemical corrodes most metals, eats rubber and plastics and destroys electronic equipment. When the Army tested it on the M-1 main battle tank, the tank was left inoperable because of damage to electronic cables, one of which started smoking minutes after coming in contact with DS-2.

In an unusually forceful recommendation, the GAO urged the Army and Marine Corps to suspend purchases of the toxic mixture immediately and adopt a safer substitute. The study noted that the Army Training Command had made a similar recommendation, but was overruled by senior Army officials.

The Air Force and the Navy have stopped using DS-2 in favor of preferred alternatives: warm soapy water and common bleach.

Despite problems with the substance, the Army insists that DS-2 will remain its "decontaminant of choice" until the 21st century. Army officials say it is the only agent that neutralizes chemical weapons, rather than merely washing them off. Other decontaminants such as soap and bleach leave toxic runoff that must be treated or otherwise disposed of, they say.

"The Army is currently evaluating less hazardous alternatives to decontamination solution 2," David J. Berteau, deputy assistant secretary of defense for production and logistics, said in a letter sent to the GAO last week. "Until one is found, however, decontaminating solution 2 continues to be the most effective multipurpose decontaminant for a broad range of potential chemical agents encountered."

The GAO study on DS-2 was requested by Rep. Mike Synar (D-Okla.), chairman of the House Government Operations subcommittee on the environment, energy and natural resources.