THE P RTAL April 2018 Page 17 Nerve agents Dr Simon Cotton is an Honorary Senior Lecturer in Chemistry at the University of Birmingham and a member of the Ordinariate N erve agents are currently in the news, following reports that two people are in a critical condition in a Salisbury hospital following exposure to a nerve agent, with others injured. But what are they and how do they work? The first nerve agents were invented by accident in the 1930s, by researchers trying to make cheaper and better alternatives to nicotine as insecticides. A German industrial chemist named Gerhard Schrader made some phosphorus-containing organic compounds that were great at killing insect pests but were too toxic to be used near humans. The Wehrmacht found out about these compounds, one of which we know now as sarin, investigated them, and began constructing plants to manufacture them as weapons. The sarin plant was not operational by the time that the Russians overran Poland and Germany (thereby acquiring a chemical warfare capability). VX was discovered in 1952 by British chemists, again trying to make insecticides – this research was eventually handed over to the Americans, who started to manufacture it in the 1960s. One accident during testing in Utah killed several thousand sheep. The so-called ‘Novichok’ (‘Newcomer’) agents – one of these is believed to have been used in Salisbury - were developed by Russian researchers in the 1940s and 1950. Most nerve agents are liquids, but some Novichok agents are thought to be solids. Unlike street drugs, nerve agents cannot be made in your kitchen or garden shed, because they are incredibly toxic. Lethal doses involve milligrams, or less. Making them requires a specialist laboratory, with fume cupboards. Workers would have to wear incredible protective clothing, because nerve agents are also absorbed through the skin; when the Nazis were building their first nerve agent plant, workers wearing protective suits died in agony when nerve agent got through gaps in the suits. Decontamination can be a problem. be a dangerous build-up; it uses an enzyme called acetylcholinesterase (AChE) to do that. A nerve agent stops acetylcholinesterase from doing its job. As far as is known, nerve agents were not employed until the 1980s. Saddam Hussein’s Iraqi forces are thought to have used sarin during the Iran-Iraq war, notably against Kurdish citizens in Halabja on 16–17 March 1988, leaving about 5,000 dead. On 20 March 1995, members of the Japanese Aum Shinrikyo cult used umbrellas with sharpened tips to puncture plastic bags and boxes containing sarin while they were travelling on the Tokyo subway system. 13 people died. VX has been used more rarely, most recently in killing Kim Jong Nam, the half-brother of King Jong Un, North Korea’s leader, allegedly by smearing VX nerve agent across his face in an airport in Kuala Lumpur on February 13 th 2017. Salisbury is believed to be the first time that a Novichok agent has been used ‘in public’. Unlike traditional poisons, nerve agents don’t need to be added to food and drink to be effective. They can be inhaled or absorbed through the skin. Symptoms of nerve agent poisoning come on quickly - usually in a minute or less - like chest tightening, difficulty Nerve agents disrupt the central nervous system. The in breathing, and very likely asphyxiation. Associated body uses a ‘messenger molecule’ called acetylcholine symptoms include vomiting and massive incontinence. to send messages between cells; when an acetylcholine Antidotes exist, one being atropine, but they have molecule ‘arrives’ it causes an electrical impulse to be sent. The body has to remove those acetylcholine to be administered quickly, otherwise the effect of the molecules from the receptors, otherwise there would nerve agent cannot be reversed.