Russia finally names mystery gas
newscientist.com
NewScientist.com news service
Russia's health minister Yuri Shevchenko has told news agencies that the knock-out agent used to end the Moscow hostage crisis was based on an opioid narcotic called fentanyl.
The agent is believed to have killed all but two of the 119 hostages who have now died, but the revelation came only after intense pressure from relatives, doctors and diplomats.
Shevchenko's comments do not appear to rule out the presence of a second compound in the agent, but it was not mentioned. Late on Tuesday, doctors in Munich reported that chemical analysis had identified the anaesthetic halothane in blood and urine samples taken from two surviving German hostages within 24 hours of the rescue.
But David Whittaker of the Association of Anaesthetists of Great Britain cautions that the two may have received halothane as an emergency treatment for bronchospasm induced by inhaling vomit, which happened to many hostages.
Cause of death
"By themselves, these compounds cannot provoke a fatal outcome," Shevchenko said. He explained the mass deaths as being caused by the use of the agent on hostages severely weakened by three days of captivity. But Martin Furmanski, a medical historian in Newport Beach, California, says one analysis of events suggests otherwise.
Rapid incapacitation was essential to prevent the Chechen terrorists donning gas masks or detonating their explosives. But administering enough of an opiate drug to cause rapid anaesthesia almost always causes a patient to stop breathing, says Furmanski. This would not be a problem in a fully-equipped operating theatre, but the siege in the Moscow theatre was an entirely different scenario.
Opioids similar to fentanyl are used in tranquilising darts for anaesthetising large animals. In these cases, the lethal dose is just six times greater than the dose needed for anaesthesia. That implies that if the Moscow hostage-takers were exposed to enough of the mixture to knock them out within one minute, hostages who kept breathing it would have acquired a lethal dose within six minutes.
"It was probably inevitable that many hostages would die if the aerosol opiate concentration was high enough to cause rapid unconsciousness in the terrorists," Furmanski says, irrespective of their physical condition.
The naming of a fentanyl-related agent confirms earlier suspicions based on the reports that had emerged since the end of the siege on Saturday. Doctors at the US embassy in Moscow said the two American survivors they examined had telltale signs of opiate intoxication.
Moscow doctors had also reportedly been treating survivors successfully with naloxone, which blocks the action of opiate drugs. And breathing failure and inhalation of vomit, said to be the most common cause of death in the hostages, are caused by opiates.
But the possibility that the opioid pumped into the theatre was mixed with halothane remains open. Halothane may have been used to extend the effect of the agent, as the fentanyl wore off. The two are commonly combined in medical use.
Russian officials may yet release further details. But they have previously expressed their reluctance to give information, saying it could help terrorists in the future. However the examination of the remains of two US hostages who died, and clothing from a British family, now being examined at the UK's chemical defense lab at Porton Down, may reveal more.
Debora MacKenzie and Damian Carrington |
