It sounds like something from a spy novel. On November 1st, former KGB secret agent Alexander Litvinenko was investigating the murder of a Russian journalist and met with two people in busy locations in central London. That day, he fell ill and checked into hospital where he said he thought he had been poisoned. His condition worsened and after a few weeks of tests at the hospital, a rare radioactive substance called polonium-210 was detected in his body. On November 23, he died from radiation poisoning.

Not only is the plot intriguing, but also the method of poisoning.  Radioactive substances are very hard to obtain and Litvinenko is the only person known to have been poisoned by polonium – a colourless and odourless substance.  Although this element is present in very low levels in the environment and in the human body, obtaining enough of it to harm a person is not likely to come from nature and would have to be man-made.  Usually synthesized in a particle accelerator or nuclear reactor, polonium can be produced through uranium decay, by chemically separating the element radium-226 or by bombarding bismuth in a nuclear reactor.

Scientists have speculated that only about one milligram of polonium could have been responsible for Litvinenko’s death.  It may seem like very little, but polonium is one of the world’s rarest elements and it is believed that only about 100 grams of it are produced every year worldwide.  Nowadays, it’s mainly manufactured for use in industrial plants where it can prevent the build-up of static electricity.  In the past, it was a component of early nuclear weapons and for the power supply system of spacecrafts in the Soviet Union.