Substance of the Year 2008





Alexander Litvinenko’s alleged murder in London in 2006 gave media exposure to the little-known element Polonium (Po).


Reports quickly surfaced that Litvinenko had died from radioactive poisoning and, within days, traces of the highly toxic isotope Polonium-210 had been found in more than 12 locations in London, Moscow, and Hamburg, and on 4 aircraft. Hundreds of people with elevated levels of Po-210 have since been traced.


Polonium was the first element to be discovered as a consequence of its radioactivity. It was isolated in 1898 by Marie and Pierre Curie, during their analysis of the radioactive ore ‘pitchblende’. Provisionally called Radium F, the element was renamed Polonium to draw attention to the political plight of Marie’s homeland, Poland, which was then under the partitioned rule of Russia, Prussia, and Austria.


Po is an extremely rare and highly toxic metallic element found in uranium ores at a quantity of c.0·1g per ton. Po has 34 isotopes (more than any other element), all of which are radioactive. The most widely used of these isotopes – Po-210 – occurs in nature at very low levels (all humans carry harmless traces). However, in sufficient quantities, Po-210 emits enough gamma particles to produce a blue glow and, according to the CDC, the alpha particles it emits ‘carry high amounts of energy that can damage or destroy genetic material in cells inside the body’. By weight, Po-210 is 250bn times more toxic than cyanide; a dose smaller than a grain of salt is fatal.


In the industrial world, Po-210 is used as a heat source for satellite power supplies, a trigger for nuclear weapons, and as a means of eliminating static. (It is also found in cigarettes; according to a NYT article by Prof. Robert Proctor, ‘pack and a half smokers are dosed to the tune of about 300 chest X-rays’ a year.)


The British Health Protection Agency notes that ‘Po-210 only represents a radiation hazard if it is taken into the body – by breathing it in, by taking it into the mouth, or if it gets into a wound. It is not a radiological hazard as long as it remains outside the body. Most traces of it can be eliminated through handwashing, or washing machine and dishwasher cycles’.


Because of Po-210’s rarity, toxicity, and difficulty of extraction, it became clear that Litvinenko’s death was unlikely to have been accidental. As Prof. Goodhead of the UK’s Medical Research Council told the BBC, ‘to poison someone, much larger amounts are required and this would have to be man-made, perhaps from a particle accelerator or a nuclear reactor’. Inevitably, speculation as to the origin of the Po-210 that killed Litvinenko focused on Russia.