New scientist article
What are Novichok nerve agents and did Russia do it?
By Alice Klein
The poison used to target ex-Russian spy Sergei Skripal and his daughter in Salisbury was a Novichok nerve agent, UK prime minister Theresa May revealed yesterday.
The chemical was identified by the Defence Science and Technology Laboratory at Porton Down, May told the House of Commons.
Novichok nerve agents – also known as the “N-series” – were secretly developed by the former Soviet Union beginning in the 1970s. They followed the “G-series” of nerve agents made by Germany in the 1930s and the “V-series” made by the UK in the 1950s. Novichok means “newbie” in Russian.
The small amount that we know about these agents is based on reports from Russian chemist Vil Mirzayanov, who exposed the development programme in 1991.
Novichoks work in the same way as other nerve agents, which disrupt nerve signals to the muscles by inhibiting an enzyme called acetylcholinesterase. The gaps between nerve cells become flooded with acetylcholine, causing continuous contraction of the muscles. Symptoms include convulsions and difficulty breathing.
According to Mirzayanov, some Novichoks can be eight times as deadly as VX, the V-series agent that was used to kill North Korean exile Kim Jong-nam last year. Just 10 milligrams of VX on the skin can be lethal.
There are no previous reports of Novichoks being used in battle or assassinations. However, Andrei Zheleznyakov, a Russian scientist involved in their development, reportedly died not long after being exposed to a small amount that leaked out of a rubber tube in the lab.
The most potent members of the N-series are reportedly Novichok-5 and 7. We know these are chemicals that contain carbon and phosphorus like the G-series – which includes sarin, tabun, soman, and cyclosarin, and the V-series – which includes VX, VR, VE, VG and VM. However, their exact structures are a mystery.
According to Mirzayanov, both are binary agents, meaning they are made from two precursor chemicals that are mixed together just before use. These precursors could be made at pesticide or fertiliser manufacturers without arousing suspicion, he says.
The use of a Novichok in the attack on the Skripals makes it highly likely that Russia was involved, because no one else knows how to make them, says John Lamb at Birmingham City University, UK. “The Novichok family was specifically created by Russia to be unknown in the West and as such it’ll be one of their most tightly guarded secrets,” he says.
But why would Russia employ such an incriminating nerve agent? “It could have been a demonstration of capability,” says Lamb. After allegedly poisoning ex-Russian spy Alexander Litvinenko with radioactive polonium-210 in 2006 without serious consequences, they may simply have felt that they could get away it, he says. Novichok precursor chemicals are also safer to transport and handle than ready-made nerve agents, he says. However, Russia has denied any involvement.
Identifying the Novichok agent would have been a painstaking process, says Martin Boland at Charles Darwin University in Australia.
If someone shows signs of nerve agent poisoning, the first thing to do is to check for decreased acetylcholinesterase activity. This reveals if a nerve agent has bound to the enzyme.
Next, the specific nerve agent must be identified. A telltale sign of poisoning with sarin, for example, is unnaturally high blood levels of fluoride, which is used to make the nerve agent.
Because no standard test exists for Novichoks, defence officials may have taken fluid from the Skripals’ spinal cords, isolated the acetylcholinesterase enzyme, and analysed the structure of the nerve agent attached, says Boland. Western intelligence agencies probably have knowledge of the exact Novichok structures, allowing them to detect a match, he says.
The Skripals are probably receiving the same treatment that is given for other types of nerve agent exposure, says Boland. This includes atropine to block the effects of acetylcholine, pralidoxime to restore acetylcholinesterase activity, diazepam to stop convulsions, and ventilation to assist breathing.
Their survival so far suggests the Novichok poison was designed to be slow-acting or to be absorbed through the skin, because this route of administrations takes longer to cause symptoms than inhalable nerve agents like sarin, says Lamb.
Parts of Salisbury – where the attack took place – are still cordoned off, and Public Health England has advised anyone who was close by to wash their clothes. This precaution is necessary because we don’t know how long Novichoks persist in the environment, says Boland.