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All the Buzz about BZ

Dan Kaszeta

Until recently, few people have ever heard of the chemical warfare agent known as “BZ”. However, in recent months, there have been accusations and insinuations that BZ was somehow used or implicated in the Skripal poisoning incident, either in conjunction with or instead of a nerve agent. This seems to stem from a statement Russian Foreign Minister Sergei Lavrov made in April 2018 claiming that a Swiss laboratory had found the substance BZ in the samples taken in Salisbury. This is, like so many other theories floated by the Kremlin, is false and designed to distract from the truth. However, it is worth unpacking this story to see what, if anything, the deal may be. 

What is BZ?

The full proper name of BZ is 3-Quinuclidinyl benzilate. BZ in its pure form is a white crystalline powder. It is not a gas or a liquid, although it can be dissolved in some solvents. It is barely soluble in water. It has basically no vapour pressure at any normal temperature. When it was used as a weapon, it was delivered by mechanisms that created smoke clouds that carried particulates of BZ, not dissimilar to CS riot control grenades. It is most effectively disseminated in particle sizes of about 1 micron (i.e. one millionth of a meter) – which is quite a fine aerosol. 

Diagram showing chemical structure of BZ

BZ can enter the human body through the respiratory tract or digestive tract. It could enter the skin, but in practice this requires the BZ to be dissolved in specialised solvents and in a much larger quantity than through inhalation. When absorbed in the human body, there are a wide variety of physical and psychological effects. It usually takes an hour or more for BZ to take effect, and the effects can last for many hours. The physical effects include fast heartbeat, dry skin and mouth, dilated pupils, flushed skin, urinary retention, constipation, and sleepiness. Mentally, BZ causes disorientation, shortened attention span, and decreased alertness in low doses. In larger doses, it causes delirium, hallucinations, and extreme agitation. A person who has been incapacitated by BZ can take days to fully recover. Death from BZ is rather unlikely as the doses that would be needed likely would require exotic circumstance or injection of large amounts. BZ is very easily identified by a wide range of normally available analytical chemistry means. Medical aspects of BZ are well explained in US military manuals, some of which are available online.

BZ is what is known as an anti-cholinergic. It is, in its chemical and biological properties, very similar to the well-known drugs atropine and scopolamine. Atropine is well known as a nerve agent antidote. In many ways, BZ works in completely the opposite way to nerve agents and would possibly be even useful as a treatment for nerve agents, were more effective drugs such as atropine not in existence. When comparing BZ to the nerve agents, it is important to remember this. Indeed, one method of treating BZ intoxication is to use the drug physostigmine, which is actually a mild nerve agent from the carbamate family. 

In particular, BZ was selected for its wide safety margin – the effective dose was very low, but a dose that was toxic is very high. In theory, BZ can kill someone, but the lethal doses are extremely high and not reasonably achievable in anything but the most exotic conditions. BZ could be dangerous in hot weather, however, as BZ causes sweating to stop and this can contribute to heat injury. 

History of BZ

BZ was first developed as a possible pharmaceutical in 1951 by the Swiss company Hoffman La-Roche as part of research into possible treatments for gastrointestinal illness. The USA developed BZ as an incapacitating chemical warfare agent in the 1960s. It was felt that a weapon that could incapacitate the enemy rather than killing him would be a preferred option in many scenarios, and in the era before the Chemical Weapons Convention, a non-lethal chemical agent was viewed as less legally troublesome. A number of compounds were explored, and the research effort settled on BZ as the incapacitation agent of choice. The US military built and operated a BZ factory at Pine Bluff Arsenal in Arkansas. By the late 1960s, the facility was producing an array of weapon systems containing BZ, primarily smoke-producing cluster bombs to be dropped from the air.

In terms of operational doctrine and actual planning for use, BZ had a more mixed picture in the US military. Offensive chemical warfare was largely the domain of the US Army, whereas BZ bombs needed to be delivered by the Air Force or Navy. The actual employment of BZ was never seriously bedded down in doctrine, was rarely if ever trained for, and most commanders felt that a hallucinogen that made the enemy more unpredictable could be a liability. As can be imagined, causing delirium in armed soldiers could be problematic. A good historical summary of the US BZ programme is here.

Other countries have developed and stockpiled BZ. The Soviet Union developed their own production programme for BZ and built a factory for its manufacture at Volsk. They called it Substance 78 and it is clearly referenced in the memoirs of Vil Mirzayanov, a defector from the Soviet chemical warfare programme. Long before the Skripal incident, an article in the New Yorker magazine referred to the Soviet BZ programme. Cold War-era Yugoslavia produced BZ (here). The claim that BZ is only an exclusively US or UK chemical is not based in fact.

BZ in Salisbury?

The idea that BZ was somehow employed in the Skripal attack is patently false, nor does it make any operational sense. Let us examine what actually happened. The Skripals, the policeman, Ms. Sturgess, and Mr. Rowley all displayed signs and symptoms indicative of nerve agent, not BZ. As noted above, the physiological action of BZ is opposite to that of nerve agents. For example, Mr. Rowley was reported to be sweating excessively, whereas BZ causes the sweat glands to stop working. The idea that trained professional medics would mistake one set of signs and symptoms for something completely in the opposite direction is worthy of derision. The course of treatment for nerve agents is very different than that for BZ and would have made the victims far worse rather quickly. In addition, nerve agents have very clear signs that can be picked up in analysis of blood samples, such as depressed acetylcholinesterase (the enzyme that nerve agents inhibit) that would not be in evidence in a BZ intoxication. In addition, a death from BZ is highly improbable in the Sturgess case, and likely impossible given the mass and volume of material available. Also, Ms Sturgess appears to have become quite ill in a manner much more rapid than any absorbed BZ could ever work. It makes as much sense to use BZ in an attempted killing as it does to rob a bank with a banana. 

The idea that BZ was somehow used in combination with a nerve agent also makes no sense. Indeed, as the two work in opposition to each other, this hypothesis verges on the nonsensical. Some of the media alleging the presence of BZ refer to it as “BZ toxin” – but this is also nonsensical. BZ is not a toxin. A toxin is a poisonous substance produced by the metabolic processes of animal, plant, or microbe. Snake venom is a toxin. But BZ is wholly synthetic. It is not a toxin. 

No competent authority, including the Organisation for the Prohibition of Chemical Weapons nor the laboratory they used (Spiez Laboratory), has indicated that BZ was found in any environmental or biomedical sample in the case. So, where does this story come from? Like many conspiracy theories, there is often a small grain of truth somewhere.  

When the OPCW sends samples to its network of laboratories, their processes follow excellent scientific and forensic practices. One of these practices includes sending positive and negative control samples along with the actual samples from the field.  The lab processing the samples does not know which samples are from the actual incident, in order to preserve the intellectual honesty and integrity of their analysis. A negative sample is one where there is known to be nothing of interest in the sample.  A positive control sample is one where something interesting has been added specifically as a test, to see if the testing laboratory can find it. In the case of the Skripal evidence, a chemical called 3Q was added deliberately by the OPCW. 3Q, as it happens, is a precursor chemical to BZ. Both Spiez Laboratory (here) and the OPCW Director General (here) clearly make statements explaining this fact. It is abundantly clear that there was no BZ involved in this case. Did Sergei Lavrov take something completely out of context and twist it to mean something completely different? Or was this an honest mistake? In any event, this is a rare example of the Russian media actually recanting its earlier tales, albeit in a way that uses the word “toxin” wrongly. However, the original RT article reporting Lavrov’s false claim is still available and still being shared by the usual crowd.


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