[MUSIC] Our final poisoning case in this lecture is a little bit different from all the others. It concerns the Russian, Alexander Litvinenko, who died of poisoning in 2006. So if we look back at Litvinenko's career, he started out as an officer in the KGB, and stayed on when the KGB converted into the FSB. By 1998, he had become a serious critic of the Russian government, and a couple of years later, he sought asylum in London, where he continued to be a critic of the Russian government. After six years in London, he became seriously ill, and he died in hospital. You can see from the picture that one of the symptoms of his illness is hair loss. So, of course, it was thought that probably this was thallium poisoning. But when he was analyzed, for instance, analysis of his urine, there was no thallium detected. And it turned out that he was being poisoned in a very, very unusual way for which there was no known precedent, and that is he was being poisoned with polonium-210. Now, polonium is a radioactive element. All forms of polonium are radioactive. Polonium only occurs naturally in very trace amounts. So polonium is actually manufactured in nuclear reactors. And one of the few places that manufactures polonium-210 is in Russia. Now, polonium-210 is radioactive. The atoms of polonium-210 decay to become lead-206, and in the process of decay, they emit an alpha particle, that is, a radioactive particle is spat out of the atomic nucleus. Now, alpha particles are not really that dangerous. They will only travel for a few centimeters in air. They will only travel for a few micrometers through the skin. So polonium-210 itself is not very dangerous, provided it's contained. But, if it is ingested, it's very, very dangerous, indeed. Because if polonium-210 is ingested, there is no barrier between these unstable radioactive atoms and your biochemical molecules. So when these atoms decay, and they give out that alpha particle, that alpha particle will smash into important molecules in your body, your enzymes, your molecular structures, your DNA. So it's not like the other poisoning cases that we've talked about before. This is radioactive atoms attacking your molecular structure. So, nothing could be done, and Alexander Litvinenko died in hospital of radiation poisoning. The thing about radiation is that it's very characteristic. The energy of these alpha particles given out by polonium-210 is highly characteristic. Other radioactive atoms that give out alpha particles, will give out alpha particles with different energies. So it's very easy to trace the polonium-210 and to confirm that it is polonium-210. So as the police follow the trail of Alexander Litvinenko around London, they were able to find more than 30 locations where there's polonium-210, including the places where Litvinenko had lunch and had tea. And it's believed that the polonium was put into his food or drink at one of the these occasions. They were also able to trace polonium-210 on two British Airways planes. In fact, they could track it to the particular seat on the plane. And these planes were flying on the London to Moscow route. So, the Metropolitan Police have a suspect in mind, someone who they would like to have help them with their inquiries. But forensic science can only do too much. It's now part of international politics. It's a question of whether the Russians will arrange for this person to ever come to London for questioning. Well this concludes our lecture on toxicology. And we've covered a lot of ground. We've talked about all sorts of different poisons, from plant poisons to carbon monoxide to inorganic poisons. We've seen some of the different modes of actions that these poisons can have, and how important it is to consider the root of administration for a particular poison. We've seen the use of the LD-50 value to measure how strong a poison is. We've seen how important it is that you keep your liver in good health to protect you from xenobiotic molecules. We had a quick look at alcohol, the most common poison. We talked about Paracelsus, and then we've seen the action of some specific poisons, such as arsenic, thallium, sarin and atropine.
