Chemistry doesn’t make the news as often as you might think, and when it does, it’s often in a grim way. Such is the case in the UK right now, with the poisoning of Sergei and Yulia Skripal in Salisbury. For those who don’t know the background of the situation, Skripal was an officer in Russian military intelligence who had actually been a longtime asset of the British government. He was arrested and imprisoned, then (after six years) was exchanged in a 3-for-10 swap of spies. At the time of this release. Vladimir Putin gave a televised interview saying, basically, that such traitors were still going to get what was coming to them.
And in such matters he (like others of his kind) is generally a man of his word. Skripal and his daughter (who was visiting from Moscow) were apparently exposed to some sort of nerve agent, which also hospitalized the first policemen to reach the scene (one of whom was seriously affected). He is reported to be conscious and alert at this point, but Skripal and his daughter, although alive as I write, are still unconscious and apparently in bad condition. The parallels with the polonium poisoning of Alexander Litvinenko would seem to be clear. In that latter case, which also took place in public in London, one theory had it that the use of polonium (a rare radioactive element that is difficult to obtain unless you have a nuclear weapons program) was a deliberately obvious calling card. But it’s also been reported that the Russian government did not expect the British physics community to be able to go so far as to identify the exact locations of its production and processing.
But what was used this time? “Nerve agent” would seem to refer to one of the reactive phosphorus compounds commonly known as nerve gases (although they’re liquids). The most likely of those would probably be either sarin or VX. There are, sadly, considerable quantities of both available in this world (sarin has been used in Syria, atrociously, and perhaps again since I wrote that post). Back in the early days of this blog (2002!) I wrote about various chemical warfare agents, and the posts on the neurotoxins are here and here. They’re both hideously lethal, and the intended message – that you can be killed, horribly, on a shopping center park bench in broad daylight – would be delivered with equal efficiency.The Porton Down research center, at any rate, has plenty of capable people who are highly qualified to deal with identifying just what was used – but was it an organophosphorus compound at all?
Update: identified today (March 12) by the British Prime Minister as one of the “Novichok” agents mentioned in the comments section a few times.
I will say that the case for an unusual nerve agent can be made by the fact that the two victims are still alive. The lethal dose of VX for a typical adult would appear to be skin exposure in the low tens of milligrams. It is known for being particularly persistent in the environment, with a very low vapor pressure, so although the responding police officers could have been exposed through skin contact on a surface, they would probably not have been affected by vapor (unless the agent was administered in some sort of solvent that azeotroped the compound along?). Sarin, though still a liquid, is much more volatile (as the Aum Shinrikyo incident in the Tokyo subway system illustrated, horribly). Something like this would seem more likely to affect bystanders or first responders, even without physical contact. But sarin is also lethal at very low concentrations, which makes the survival of the victims unlikely.
To that point, I have long wondered why only eight people died during the Tokyo attack (some of these were the transit workers who directly handled the bags of sarin that the Aum members had dropped in the subway and punctured with sharpened umbrellas). I have not seen further analysis, but my thought, even at the time, was that the material must have (fortunately) been quite impure, considering that the Aum members were carrying near-liter quantities of liquid.
The Russian services, one assumes, have access to higher-quality material. It would appear that the victims were hit with something unobtrusive and fast-acting, and you would think that anything in that category would also be very likely lethal in short order. So it could be that this was (again) a deliberate choice of poison, because you’d think that if the idea was for the victims to die quickly that that could have been arranged. The organophosphorus poisons fit the fast-unobtrusive-lethal description perfectly, but if one was used, why everyone involved did not die in short order is a mystery. There are fungal, marine, and cyanobacterial poisons that also fit the broad description of “nerve agent”, and it might turn out that one of these is the poison here instead – in which case, it might be that the same “Don’t doubt who did this” message is being sent as with the Litvinenko case. As if any reasonable observer had any doubt to start with.
Update 1: The BBC is apparently reporting, via an unnamed source, that the agent used was not sarin and not VX, but something more “rare”. Which might take us to the sorts of natural-product based compounds mentioned in the last paragraph, although I (fortunately) have no idea about their skin penetration, routes of delivery, etc.