Expert questions Army's investigation of March VX alarm at Depot

By Rob Jordan
Star Staff Writer
07-29-2004

Almost five months after a perimeter monitor at the Anniston Army Depot indicated VX nerve agent in the air, Army scientists have no definitive explanation for the March 1 incident. Officials say that an unknown “interferant” likely tripped the alarm. An interferant is a substance which, when measured by the monitor, exhibits some characteristics similar to an agent being monitored. One expert questioned the thoroughness of the Army’s investigation and said that monitor analysis had been incomplete. Because no other monitors detected agent and no evidence pointed to a leak, Army officials said recently, the monitor likely detected an organophosphate, a compound commonly found in pesticides and some organic substances. Organophosphates share a makeup similar in some ways to VX. Substances, such as a chemical used in roofing work at the Anniston chemical weapons incinerator, have set off agent monitor alarms in the past, but tests proved negative, according to Tim Garrett, the Army’s site manager there. Julie Fischer, a chemical weapons expert at the Henry L. Stimson Center, an independent public policy institute in Washington, said the Army’s conclusion is “reasonable” based on available evidence, but the incomplete nature of the monitor testing method is “troubling.” On March 1, an instrument called a gas chromatograph indicated VX in all three sample tubes taken from the monitor on the border of Pelham Range near Gate 3 Road. After producing a result and a confirmation, the third sample would normally be put aside. Instead, because one of the tubes failed a quality-control test, scientists tested all three, eliminating the samples in the process. Army scientists did not run any of the samples through a more sensitive instrument, called a mass spectrometer, in accordance with standard procedure, because the instrument had not yet been certified to test for VX, according to Army chemist Bobby D. Phillips. An independent lab would not have been able to test the substance in time to ensure an accurate result, said Army spokesman Mike Abrams. In the days that followed, Army technicians inspected weapons storage areas, or igloos, and found no VX leak, according to John Harsch, director of chemical missions operations at the stockpile. It would have taken the explosion of at least 20 pounds of VX – which would be immediately detectable by igloo monitors – for an amount of agent sufficient to be detected to have reached the perimeter monitor about four miles away, Harsch said. He added that the wind wasn’t blowing in the right direction to have carried agent from an igloo to the monitor in question. Harsch said he hadn’t heard anything from perimeter security guards that indicated anything unusual that day. Army officials ruled out the incinerator as a possible source because it has yet to begin destruction of VX munitions. Army officials said they are confident the substance detected was not nerve agent. Fischer questioned that stance. “I would want to do more than just say, ‘Well, I can’t find the source of a positively identified leak, so let’s just assume that it’s an interferant,’” Fischer said. Abrams said he respects Fischer’s point of view, but “I don’t think there’s anything that (officials at the Anniston site) would want to say in response to her opinion.” The perimeter Depot Area Monitoring System should be considered only one of several information “inputs,” officials said. It is intended to confirm or negate on-base alarms and help track agent plumes — not to provide a first line of detection. The system is the best available, according to Garrett, who said a laser monitor technology advocated by some groups have would not have detected such minute amounts of VX.

About Rob Jordan

Rob Jordan covers criminal justice issues for The Star.