Sunday, December 03, 2006

Cloak and Dagger in London

Over the past month, I have been following the news from London, about the poisoning of former Russian spy Alexander Litvinenko. After more than three weeks of convalescence in a hospital, Litvinenko passed away on November 22, and the autopsy after his death identified a very unusual radioactive poison in his system: Polonium 210.

In the time since, the news media has not done a very good job of explaining to the public what this stuff called polonium is, and how it would have killed Litvinenko, and why this substance was so hard for British doctors to detect until after Litvinenko's death. So, I will take some liberty here.

Polonium is a naturally occurring radioactive substance. As natural uranium decays, one of the substances that is produced is polonium. Thus, it can be found in very small concentrations in natural uranium (which is how Marie and Pierre Curie first isolated it in 1898).

There are four types of radiation that can come from a radioactive substance: alpha radiation (two protons and two neutron together), beta radiation (tiny electrons or positrons), gamma radiation (high-energy photons), and neutron radiation (neutrons).

While this technical jargon may not make a lot of sense to many people, the important thing to note is that alpha particles are huge compared to the others. This means two things: alpha particles can't go very far (they can't even penetrate a piece of paper), but they do a lot of damage when they hit something. A guy on a bicycle can navigate through smaller spaces than a bus, but which would you rather be hit with if you're walking across the street?

What this means is that a radioactive substance that is an alpha emitter is not dangerous outside the body, as the alpha rays it emits cannot penetrate more than a couple of inches of air, and if you touch it, the alpha radiation cannot penetrate through the outer layer of your skin. But, if you ingest or breathe in the alpha emitter, that is another story, as the alpha particles will be emitted inside your body, and can do a huge amount of damage. But, the alpha particles cannot be detected outside the body.

Polonium is an alpha emitter. But, what makes it special is that it doesn't emit a gamma ray at the same time as it emits an alpha particle, which makes it really hard to detect. Gamma rays are easy to detect, but alpha rays, because they don't go very far, are not. This is why Litvinenko was sickened with symptoms of radiation poisoning, and yet no radiation was detectable from outside his body. The polonium, from within his body, did all the damage.

Another key consideration with polonium is it is very difficult and costly to obtain. It is not something you can buy off the shelf at your local hardware store. It must either be purified from uranium (a costly and time consuming process) or produced in a nuclear reactor. This does tend to suggest that someone such as a government entity may have been behind Litvinenko's poisoning, as it would be exceedingly difficult for anyone else to obtain sufficient quantities of this substance. It seems likely that the main reason for this particular poison being chosen was because of the difficulty with detecting it.

It also seems likely that whoever selected polonium as the poison of choice was hoping that it would kill Litvinenko quickly, and be prohibitively difficult to detect. In that situation, doctors would have been in a quandary to explain how a healthy man can suddenly die like that, and the death would have been chalked up to a mysterious death, and not a murder, and certainly not a state-authorized assassination. But, this did not happen. The dose of polonium administered to Litvinenko was too low to kill him quickly (perhaps a crucial error on the murderer/assassin's part). Instead, it left Litvinenko in a hospital bed with characteristic symptoms of radiation poisoning, conscious enough to talk to investigators and to write a deathbed letter accusing Vladimir Putin of ordering his murder. The fact Litvinenko's symptoms were so characteristic of radiation poisoning led to tests being conducted during his autopsy to identify the radioactive substance. And, the fact polonium is so rare in nature and difficult to obtain points a finger towards a state sanctioned assassination.

If this was really an assassination with polonium, I expect it will be the last we will ever see. The assassin/murderer would have been better off killing Litvinenko with arsenic or ricin or one of these other easier to obtain poisons. Yes, it would be more detectable, but once the poison is detected, it would have been easier for Russia to deny having anything to do with the murder. With it being done with polonium, however, the cloud of suspicion around Russia is much thicker, since they are one of the few countries that has the ability to produce it.