STEVE INSKEEP, HOST:
The former Russian spy and his daughter remain hospitalized in Britain. Both collapsed near a shopping mall over the weekend. They're in critical condition. Sergei Skripal is a former Russian military intelligence officer who was convicted by the Russians in 2006 of selling secrets to the British. He now lives in Britain, understandably. And police say he and his daughter were poisoned by a nerve agent. We're going to talk about this with professor Alastair Hay, who is a toxicologist at Leeds University.
Welcome to the program, sir.
ALASTAIR HAY: Thank you. Good morning.
INSKEEP: Let's try to figure out what is known based on the police statements. What kinds of chemicals could be used in this way?
HAY: Well, the nerve agents have been identified. Nerve agents are chemical warfare agents designed only to kill. And you can be fairly certain if they've said a nerve agent is being used, there's laboratory evidence for that.
INSKEEP: And how is it that they would affect people?
HAY: Nerve agents work by blocking the message from the nerves to the muscles. So all of your muscles go into spasm. So people feel weak because they can't stand. Your heart rate is affected. You're all confused because of the effects on the brain. But most importantly, it's the muscles that control your breathing that cause the problem. So people asphyxiate. You get incredible infusion of fluid into the lungs as well, which complicates the breathing.
INSKEEP: I have to say one surprise here - just as a layman - is that the victims would be alive at all because you do learn that even very small amounts of nerve agents will kill you.
HAY: Absolutely. And dosage - that is the amount they've received - is critical in this instance. If they have not received several lethal doses, then the chances of survival if you can get them to intensive care are improved. Some of the signs that the individuals displayed may have given the doctors a clue as to what it was, and they could have started administering some antidotes on the assumption that it was a nerve agent. I don't know that at this stage.
INSKEEP: Well, how would someone administer a nerve agent to a couple of people in a populated area?
HAY: Well, the agents are effective through inhalation, ingestion - that is swallowing - or through skin contact. So it could have been any one of those routes. It was clearly very targeted because it was these two people who were critically affected and a police officer who probably got exposed through some residual contamination. So very focused, but we don't know exactly how it was administered yet.
INSKEEP: Now, we don't know that this can be directly linked to Russia at this time, but when people hear about this story, they naturally think of an occasion in 2006 in London where a former KGB officer was poisoned, in that case by Polonium 210. Do you see any similarities between that incident and this one involving nerve agents?
HAY: Well, people are making all sorts of links. I think at this stage, it's very difficult to point a finger at anybody. There's a lot of circumstantial evidence pointing to why Russia might be a possibility. But I think until we've got good evidence, I think we should be circumspect in who we finger.
INSKEEP: If you were part of the investigation, what questions would you be asking next?
HAY: I would want to know much more about the details of the movements of the couple. I would want - I want to find environmental samples because the way the agent was made might give me a clue as to its source. And I would want to try and contact as many other people who saw the couple as possible to get evidence.
INSKEEP: Professor Hay, thanks very much.
HAY: You're very welcome. Bye-bye.
INSKEEP: Alastair Hay is a toxicologist at Leeds University in Britain. Transcript provided by NPR, Copyright NPR.