Cold War-era nerve agent benzilate
March 9, 2018 -- Known as BZ, QNB or Agent 15, the Cold War-era nerve agent benzilate blocks chemical signals throughout the central nervous system -- the brain and spinal cord -- and peripheral nervous system to the rest of the body.
In 1952, chemists at Swiss pharmaceutical company Hoffman-La Roche created a drug to treat stomach ulcers, 3-quinuclidinyl benzilate. While the drug was successful in treating ulcers, it had a side-effect -- it caused hallucinations.
However, the colourless liquid with a slightly fruity odour caught the attention of scientists working at the U.S. Army Chemical Centre on a project to develop potential “incapacitating agents.”
After five years, researchers had concluded that LSD and marijuana were too unpredictable to be useful as hallucinogenic weapons. Systematic testing of 3-quinuclidinyl benzilate -- now called benzilate, BZ or Buzz -- began in July 1960.
Army psychiatrist James Ketchum, who worked on the programme from 1960 to 1969, describes the development of BZ in his memoir “Chemical Warfare: Secrets Almost Forgotten.”
By March 1963, more than 300 healthy enlisted men had volunteered for periods of experimentation at Edgewood Arsenal, northeast of Baltimore, Maryland. There, army doctors administered BZ orally, injected into veins and muscles, absorbed through inhalation and skin contact.
Studies of the pharmacology of BZ confirmed its potency. A dose of 5 or 6 micrograms per kilogram of body weight of BZ triggered hallucinations. The equivalent to a barely visible grain of sand rendered a soldier incapable of functioning for two to four days. The lethal dose was estimated to be 40-times this incapacitating dose.
BZ is absorbed through the lungs and rapidly crosses the blood-brain barrier. Once in the brain, BZ molecules seek out receptors for acetylcholine and serotonin molecules, the neurotransmitters that trigger physical and mental activity.
Usually, an enzyme breaks the transmitter down to free up the receptor site to prevent over-stimulation. Now blocked by the more potent BZ, the receptors continually fire off impulses. Blocked serotonin receptors lead to sensory overload and hallucinations while blocked acetylcholine receptors over-stimulate muscles to spasm, causing rapid loss of control of vital functions such as heart and respiration.
Bosnian Serbs possibly used BZ shells against an exodus of over 12,000 people from the enclave of Srebrenica in July 1995. Two‐thirds were captured or killed, and many of the survivors experienced hallucinations.
In December 2012 reports emerged from the city of Homs, in Syria, that government forces had used “Agent-15”, a BZ-type nerve agent that poisoned scores of people and caused hallucinations and behavioural changes.
The United States destroyed its stockpile of BZ cluster bombs in the late 1980s.