WASHINGTON, March 25 (UPI) -- At least five of the 60 possible biological weapons laboratories U.S. forces have examined in Afghanistan have yielded tiny amounts of anthrax or ricin, the highly toxic derivative of the castor bean, according to Gen. Richard Myers, chairman of the Joint Chiefs of Staff.
"The caveat to that is that there's such minute amounts that the anthrax could be naturally occurring, and the ricin could be there because of the castor bean. It could be that. And so, no, no conclusive proof of active agents," Myers said at a Pentagon news conference Monday.
One of the sites -- an apparent anthrax laboratory -- was discovered over the weekend in Kandahar. It appeared operators were in the process of shutting down the lab when they left, Myers told reporters after the briefing. The lab was not fully equipped to produce biological agents that could be used in germ warfare, Myers said.
"There was a dryer. There was an autoclave," Myers said. "Not all the equipment you would need was there, but there was some of the equipment. Looked like some of it had been tried to have been destroyed."
Trace elements of anthrax were identified in the lab but the amount was so minute they may be from naturally occurring sources, Myers cautioned.
Myers said the information that led U.S. forces to the site in Kandahar clearly connected the lab to a weapons program.
"Not only what we found there, but what led us to that particular site and how all that came together, it came together that that was a site they were using, from a good source, and so we went and we found what we found," he said.
There are civilian or "dual" uses for ricin and anthrax, making it possible that the labs -- if they were producing the toxins -- may have been engaged in legal activities.
However, Defense Secretary Donald Rumsfeld said the terrorist group al Qaida's known appetite for biological weapons makes that possibility immaterial if not remote.
"We have so much evidence in writing of the desire to develop capabilities, chemical and biological capabilities, that the fact that it's dual use is saying a pistol's dual use; it can shoot at a target or it can shoot at a person," Rumsfeld said.
If caught in time, anthrax can be treated with antibiotics. There is no similar treatment for exposure to ricin.
Ricin is a highly toxic derivative of the common castor bean and is an active ingredient in brake fluid, among other things. Ricin can be drawn out of the bean and if inhaled can kill the victim within 36 to 72 hours of exposure. If ricin is injected into the skin, death is normally attributed to vascular collapse, usually within 72 hours.
Ricin was believed to be the culprit in the 1978 death of Georgi Markov, an exiled Bulgarian broadcaster. He was waiting for a bus in London when he was jabbed with an umbrella; he died three days later. During the autopsy, the coroner discovered a small metallic sphere with two tiny holes inside Markov's wound, which he surmised to have carried the toxin.