On April 29, an international treaty banning chemical weapons went into effect. Ratified by 75 nations, including the United States but not Russia, the Chemical Weapons Convention stipulates that members must destroy all chemical stockpiles by 2007.

The U.S. Army began incinerating the

The United States has about 30,000 tons of chemical weapons stored, including World War II-era mustard gas and the lethal nerve agents sarin and VX. Incinerators are now operating at two of the nine U.S. storage sites: on Johnston Atoll, about 800 miles south of Hawaii, and in Tooele, Utah (SN: 12/10/94, p. 394).

Because some of the chemicals are loaded into weapons, such as rockets, bombs, and mines, the problem of disposal is complicated. Of the available technologies, incineration most efficiently destroys contaminated metal and plastic parts, says Mickey Morales of the Army's Aberdeen (Md.) Proving Ground. After the weapons are disassembled robotically and drained of their contents, the chemicals and the tainted components are burned in separate furnaces. Exhaust gases are captured and treated to remove toxic substances.

Careful monitoring of emissions and numerous safety features make the design "the Rolls Royce of incinerators, compared to the ones that are normally permitted to operate in this country," says Amy E. Smithson of the Henry L. Stimson Center, a public policy research institute in Washington, D.C.

Some groups believe incineration of chemical weapons is unsafe. In ratifying the treaty, the U.S. Senate added a provision to extend the deadline 5 years if an alternative method is found. These extra years should provide sufficient time for development, says Craig Williams of the Chemical Weapons Working Group in Berea, Ky., an advocacy group opposed to incineration.

The risk of storing the weapons for that additional time is greater than the minimal risk of burning them, says Donald L. Siebenaler, director of a National Research Council committee that evaluates the Army's disposal program. For example, some nerve agents are loaded onto M55 rockets, which are potentially unstable and could blow up, Smithson says.

The Army is currently studying alternative disposal methods, says Morales, but getting permits for any new technologies will take years. The Army plans eventually to neutralize mustard gas and VX stored in bulk at two sites (SN: 10/5/96, p. 218). Destroying chemicals in bulk with alternative methods is not hard, says Smithson, but once the chemical is part of a weapon, "you're dealing with a deadly agent next to propellants and explosive agents."