Polonium-210 has been in the spotlight since it was identified as the poison that killed Alexander Litvinenko, a former officer in Russia's internal security service. Karl K. Turekian, professor of geology and geophysics at Yale University, explains its basic qualities, where and why it is produced and how it destroys human tissue. In an interview with National Interest online editor, Ximena Ortiz, Turekian also says that the decision to look for polonium as a source of the poisoning required a high-degree of sophistication and possibly some prior knowledge.

NIo: Could you explain what polonium is?

KKT: First of all, the basic chemistry of polonium: It's everywhere naturally. Polonium-210 occurs in anything that has uranium, but the levels are very, very low.

During the development of the atomic bomb, what was needed was an initiator, something that would get the uranium-235 to start fissioning. They developed a way of manufacturing polonium-210 artificially with bismuth-209. They took that polonium and combined it with beryllium. This emits neutrons at just the right energy to initiate a nuclear reaction. That's still the major use of polonium-210 now.

When polonium-210 was fabricated in such large quantities-they would actually machine it and make shapes, and things like that-they also started using it for reactors in satellites. So there is that use to it as well.

Anyhow, wherever there is a nuclear arsenal, there's polonium-210. It has a half-life of 138 days, which means if you start with ten grams, in 138 days it will be down to five grams and in another 138 days it will be down to 2.5. It will be effectively gone in three and a half years. So they have to keep manufacturing it.

NIo: Do all nuclear states manufacture polonium?

KKT: Everyone uses polonium-210. People quickly realized they needed an initiator, and polonium-210 is the initiator of choice for a lot of reasons.

NIo: Does it make a difference if you manufacture a uranium bomb versus a plutonium bomb?

KKT: All of them need something to provide neutrons to initiate the reaction.

NIo: Would civilian nuclear reactors also use polonium?

KKT: My guess is that polonium-210 is not necessary for a nuclear reactor for energy production, though I'm not an expert in that area. It's actually manufactured from bismuth in nuclear reactors. Whereas bombs in their compact state-with a core of plutonium-210 and beryllium-are dependent on it.

NIo: So you wouldn't be producing it if you're not producing a bomb?

KKT: Probably not.

NIo: Once you obtained polonium-210, how would you use it as a poison?

KKT: Polonium-210 is called an alpha emitter. Alpha is essentially a helium atom stripped of all its electrons, and it comes out with a tremendous amount of energy. It does not have a long range, however; you can put a piece of paper over it and it stops the particles. They do a lot of damage close up, but they don't go great distances. You could carry it around in a box, and no one would know you had any by the radiation. It would get warm if you had a lot of it, but no one could detect it if you had a vial surrounded by sawdust.

That's also the source of its hazards. Being an alpha emitter, with these very energetic, charged particles, if it bombards tissue it destroys the tissue, or causes it to mutate. People have been studying that for quite awhile, for a lot of reasons including the hazards of second-hand smoke. It has an interesting history. A massive dose of alpha particles next to human tissue would cause damage that could lead to sickness and death.

NIo: How could one use it as a poison without hurting themselves?

KKT: Remember the rays aren't like X-rays or gamma rays that penetrate a great distance. This stuff, the radiation isn't going to go beyond the cardboard box. It's easy to handle as long as there's a container.

NIo: What about removing it, how would you poison another person? Would you put it into food?

KKT: Well, you could put it into food. It would act like a small explosion in the cells, and that's where the damage is done. It could also be inhaled, but I don't think that's what you would do to someone else. You're not going to use an aerosol spray in the air you're breathing.

NIo: How would you go about exposing the food to the polonium?

KKT: I'm not really a chef. You don't need a whole lot of it, though; adding it to food in some way or another need not be obvious or ostentatious.

NIo: It still seems like such an exotic property to choose, though.

KKT: Well, there's plenty of polonium-210 available-any place there's a bomb maintenance facility-and it's always manufactured. It is a sophisticated thing to know that polonium-210 is dangerous, but that's been known because it did a lot of harm to people throughout the Manhattan Project.

Beyond that, I have no idea. I was surprised that somebody was clever enough to look for polonium-210 during the investigation. If you were looking for alpha emitters, there is a diagnostic energy for polonium-210 no one would mistake. But the act of looking into that shows some insight into what might have been used, and I have no idea how they got that insight. Maybe they knew something about this person or the people he hung around with.