Science Interviews

Interview

Sun, 3rd Dec 2006

Polonium 210

Dr Mark Peplow, editor of Chemistry World from the Royal Society of Chemistry

Part of the show Naked Science Q&A and Polonium Poisoning

Chris - It's been a week or two that's really recreated something that I don't think Ian Fleming could have recreated in the James Bond series; stories about KGB agents knocking off ex-Russian agents and Alexander Litvinenko dying from polonium 210 poisoning. But what actually is polonium 210 and how does it actually do away with people when it gets inside your body? How do you get hold of it and how do you get it inside your body? The editor of Chemistry World from the Royal Society of Chemistry, Mark Peplow, joins us to tell us. What is actually is it, and if I wanted to get some, where would I get it?

Mark - Well this is one of the most bizarre things about this case. It's a very very rare element; a silvery sort of metal. When it was first discovered by Marie and Pierre Curie back in 1897, they did it by trawling through uranium ore, but you only get about 100 micrograms of this stuff in every tonne of uranium ore. So these days you make it by bombarding an element called bismus with neutrons. Now the only way you can do that is in an experimental reactor.

Chris - So that means that somebody must have had access to some pretty high class technology to be able to do this. It's a well-planned and orchestrated attack.

Mark - Absolutely. This is something that you can't just go out and set up yourself. There are maybe only forty facilities around the world that are capable of making this stuff. Funnily enough, Russia actually exports about eight grams of polonium 210 every month, and all of it to the US. It does have a very small use to help discharge static that builds up in certain types of machinery. But other than that, it's not really made very much at all in the world.

Chris - So how much would you need to get inside your body to be harmful?

Mark - The maximum safe dose you could get away with is seven trillionths of a gram. That's a minuscule amount. According to the doctors, the sorts of doses Litvinenko took or was given was substantial enough to cause this very rapid onset of radiation poisoning. That might only be micrograms or milligrams though, so it's the sort of amount that could constitute something smaller than a pea.

Chris - Why do you think someone would have gone for such an exotic way to kill someone? Wouldn't something like lead poisoning in the form of a bullet have been more effective and probably easier?

Mark - Yes, it's very bizarre. This now gets into the realms of a spy thriller and something that is really speculation. From one point of view, it sends out a very powerful message that whoever has done this does have access to some very serious pieces of kit and is able to move radioactive material around the world almost certainly. On the other hand, it may have been a geniuine attempt to try and disguise the mode of poisoning of this guy. Obviously he was sick for quite a few weeks before people realised exactly what had poisoned him, despite the fact that experts at University College London had been testing him and looking at him to treat him. This may have been one of the reasons to use the polonium. It's simply so rare and there's no other documented cases of deliberate poisoning by this metal, that it may have been to cover up the fact that this guy had been poisoned in this way.

Chris - You don't think for instance that this is a KGB calling card. They're saying that you can't prove anything, but it's obvious who's done it.

Mark - Well like I say, it may be a very obvious way to say 'look, we have the technology and we can get to you with some really bizarre stuff that you need serious contacts and power to get hold of.' So yes, that may be one explanation.

Chris - And once you've got this stuff inside your body, why does it actually make you unwell?

Mark - Because it gives out radiation, the type of radiation it gives out is called alpha particles. It's a bundle of two protons and two neutrons; the little particles that make up all the atoms that make up all the different elements in the universe. These alpha particles can work in two ways. Because they're positively charged, they can rip electrons away from the molecules that are found in your body cells that are responsible for doing all the biochemistry needed to keep you living. In doing so, they make things called free radicals, and that can help to break down all the different biochemical reactions that are going on. That can cause you illness. In the longer term, the alpha radiation can damage DNA in your cells. It can damage the DNA to such an extent that the cell realises how badly warped its DNA has become and that can actually make it shut down. The cell will kill itself in a process called apoptosis because the cell has undergone such rapid damage.

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