MARY LOUISE KELLY, HOST:
To the U.K. now where the front pages are once again filled with headlines about Novichok. Novichok, of course, first made headlines back in March when former Russian spy Sergei Skripal and his daughter were found unconscious on a bench in Salisbury. British officials said the pair had been poisoned by a nerve agent, and they said the trail led directly to Russia. Now, four months later, another two people are sick, critically ill and in the hospital. And security officials say they, too, were exposed to Novichok, which prompted us to wonder, what exactly do we know about Novichok and how it works and how it's spread? Well, for some answers, we have called Alastair Hay. He is emeritus professor of environmental toxicology at the University of Leeds in Britain, and he joins us via Skype. Professor Hay, welcome.
ALASTAIR HAY: Thank you very much. Good evening.
KELLY: Compared to other chemical weapons, how lethal is Novichok?
HAY: Oh, they are certainly lethal. They're like all nerve agents, and they work in the same way in that they block a crucial enzyme which regulates messages between nerves and muscles and effectively sends muscles into spasm. And that's the muscles that control your breathing, keep you upright, control your vision, your heart, your gut, your intestinal movement. So absolutely every muscle is affected, and that has very serious consequences. The most important of which is inhibition of breathing.
KELLY: So help us square what you're telling me about how lethal this toxin is with the advice that British medical experts have been giving - even today - saying, look, the risk to the public is low. If you maybe have been in the vicinity, wash your clothes and use baby wipes.
HAY: Well, we know from the evidence of the Skripals and the two people who are currently affected that they were exposed to a serious dose and unconscious as a result. And I think in the case of the Skripals, they would certainly have died had it not been for the good treatment they had in hospital. So this suggests that the dose that the individuals who were exposed to was a lethal one.
KELLY: How much would you need to have a lethal dose?
HAY: Oh, you're talking about microgram quantities. Maybe 50 to a hundred micrograms, you know, and a microgram being a millionth of a gram - so tiny amounts really.
KELLY: And is it something that could wash away? I mean, I'm struck by the fact that the second set of cases - this is happening four months after the Skripals.
HAY: Yes. The nerve agents, generally, are not very soluble in water. They are degraded by water ultimately. The other factor that governs their disappearance is temperature. And the warmer it is, the more - they will evaporate.
KELLY: One of the interesting twists of this new case - this couple that are British - citizens, civilians, no known contacts with Russian intelligence. This latest couple to get sick - is that they were in a town seven miles away from where the Skripals were poisoned.
HAY: Well, the suggestion is that - and the evidence is that they visited Salisbury where the Skripals lived. And they perhaps visited one of the sites where the Skripals may have been or where something may have been discarded, perhaps even by those who were the perpetrators of this incident in the first place and the ones who placed the Novichok on the door handle of the Skripals' house. We don't know that yet.
KELLY: What are the key outstanding questions to you, from a scientific point of view, as this investigation plays out?
HAY: Well, for me, it's possibly having some idea whether it was from the same likely batch of material that was used against the Skripals. It's also how the couple came into contact with the agent and whether that indicates anything about the robustness or otherwise of the approach to decontaminate the area. Those are the two major questions that I have.
KELLY: Professor Hay, thanks very much.
HAY: You're very welcome. Nice to talk to you.
KELLY: Alastair Hay. He's professor emeritus of environmental toxicology at the University of Leeds.
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