The chemical agent used in the Moscow theatre hostage crisis has never been definitively revealed by the Russian authorities, though many possible identities have been speculated. An incapacitating agent of some kind was used by the Russian authorities in order to subdue the Chechen separatists who had taken control of a crowded theatre.

It was reported that efforts to treat victims were complicated because the Russian government refused to inform doctors what type of gas had been used. In the records of the official investigation of the terrorist act, the agent is referred to as a certain "gaseous substance", in other cases it is referred to as an "unidentified chemical substance" (conclusions of forensic examination commission, Volumes 30-33 of the criminal case).

At the time, the gas was surmised to be some sort of surgical anesthetic or chemical weapon. Immediately after the siege, Western media speculated widely as to the identity of the substance that was used to end the siege, and chemicals such as the tranquilizer diazepam (Valium), the anticholinergic BZ, the oripavine etorphine, and the anaesthetic halothane were proposed. Foreign embassies in Moscow issued official requests for more information on the gas to aid in treatment, but were publicly ignored. While still refusing to identify the gas, on October 28 2002 the Russian government informed the U.S. Embassy of some of the gas's effects. Based on this information and examinations of victims, doctors concluded the gas was a morphine derivative.

Two days after the incident, on October 30 2002, Russia responded to increasing domestic and international pressure with a statement on the unknown gas by Health Minister Yuri Shevchenko. He identified it as a fentanyl derivative, an extremely powerful opioid. Boris Grebenyuk, the All-Russia Disaster Relief Service chief, said the services used trimethyl phentanylum (3-methylfentanyl, a superpotent fentanyl analog that is about 1000-times more potent than morphine, that was manufactured and abused in the former USSR); New Scientist pointed out that 3-methylfentanyl is not a gas but an aerosol. The research made by American scientists into fentanyl derivatives shows that their lethality level surpasses the efficiency of traditional lethal methods: the lethality degree of the chemical weapons used in World War I was 7%, while in Dubrovka theater it exceeded 15% [491568].

A German toxicology professor who examined several German hostages said that their blood and urine contained halothane, a surgical anaesthetic not commonly used in the West, and that it was likely the gas had additional components. No other unusual chemical substances have been detected. However, halothane has a strong odor (although often defined as "pleasant" by comparison with other anesthetic gases). Thus, by the time the whole theatre area would be filled with halothane to a concentration compatible with loss of consciousness (0.5% - 3%), it is likely that terrorists inside would have realized they were being attacked. Additionally, recovery of consciousness is rapid after the flow of gas is interrupted, unlike with high-dose fentanyl administration. Therefore, although halothane might have been a component in the aerosol, it was probably not a major component, or perhaps it was a metabolite of another drug.

Writing in the Moscow daily Komsomolskaya Pravda, Viktor Baranets, a former Russian Defense Ministry official, stated that the Ministry of the Interior knew that any normal riot control agent, such as pepper spray or tear gas, would allow the terrorists time to harm the hostages. They decided to use the strongest agent available. The paper identified the material as a KGB-developed "psycho-chemical gas" known as Kolokol-1, and reported that "the gas had such an influence on [Chechen siege leader Movsar] Barayev that he couldn't get up from [his] desk". Russian doctors who helped hostages in first minutes after the siege used a common antidote to fentanyl, naloxone, by injection. But the effects of the fentanyl derivative's application, which can cause chronic diseases, grew acute for the hostages, who had stayed in a closed space without water and food for several days.

Prof. Thomas Zilker and Dr. Mark Wheelis, inteviewed in BBC's Horizon documentary, dispute that the gas could have been based on fentanyl.

Prof. Thomas Zilker: It seems to be different from fentanyl, carfentanyl and sufentanyl but it has to be, it has to have the potency of carfentanyl at least because otherwise it wouldn’t work in these circumstance.

So the Russians obviously have designed a new fentanyl which we can not detect in, in the west.

Dr. Mark Wheelis: The fact that the Russians did it and got away with a lethality of, of less than twenty percent suggests to me that very likely there may have been a novel agent with a, with a higher safety margin that normal fentanyl.

Although the exact nature of the active chemical has not been verified, the Russian language newspaper Gazeta claimed that the chemical used had been 3-methylfentanyl, which is an opioid, attributing this information to "experts from the Moscow State University chemistry department".

References

1. Russia Confirms Suspicions About Gas Used in Raid - Potent Anesthetic Pumped Into Theater - 2 More Hostages Die From Drug's Effects, Susan B. Glasser and Peter Baker, Washington Post, 2002-10-31 A.15
2. Mystery of Russian gas deepens NewScientist.com news service, Debora MacKenzie, 2002-10-29
3. Unexpected “Gas” Casualties in Moscow: A Medical Toxicology Perspective
4. Peterson, Scott. (October 29, 2002). Gas enters counterterror arsenal - The unprecedented use of a secret toxic gas leaves 400 still hospitalized, and starts a debate about Russian tactics. The Christian Science Monitor, WORLD; p. 1.
5. CHECHEN-NORTH-OST SPECIAL FORCE OF RUSSIA N 11 (74) NOVEMBER 2002 in Russian, last three paragraphs
6. http://www.bbc.co.uk/science/horizon/2004/moscowtheatretrans.shtml

External links

• Gas 'killed Moscow hostages', BBC News, 27 October, 2002
• Hostages given military's nerve gas antidote, The Guardian, October 28 2002
• What was the gas?, BBC News, 28 October, 2002
• Gas enters counterterror arsenal, The Christian Science Monitor, October 29, 2002
• German doctors identify gas used in Russian hostage rescue, CBC News, October 29, 2002
• US identifies deadly Moscow siege gas, BBC News, 29 October, 2002
• Russia names Moscow siege gas, CNN, October 30, 2002