A SHADOW from the cold war descended on the UK last week when a former Soviet spy resident in London died from poisoning with polonium-210. Alexander Litvinenko鈥檚 death is reminiscent of the gruesome ways that dissenters used to be dealt with by Soviet-bloc states. Not since 1978 has London seen the like. In that year, at the behest of the KGB, Bulgarian broadcaster Georgi Markov was killed with a pellet filled with ricin.
Polonium-210 is not a substance to mess with. Weight for weight it is 250 billion times as toxic as hydrogen cyanide. It is chemically poisonous and a potent source of alpha particles. As these collide with other particles they generate heat: 140 watts per gram of the isotope. In the body, energetic alphas smash up DNA and interfere with cell division. Just 120 nanograms can deliver a fatal dose of radiation.
Alpha particles travel no more than a few centimetres in air and are stopped by a thin layer of materials such as glass. This makes polonium-210 easy to smuggle (see 鈥淧oison needed state support鈥�). It has soluble salts, so it would be easy to introduce into food. At least some of it would cross the gut wall and enter the bloodstream.
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Polonium-210 may kill with ease, but it is hard to get hold of. Few places in western Europe make it. The UK鈥檚 National Physical Laboratory can make picograms by separating it from lead-210, which decays into polonium-210. Larger quantities require a reactor in which bismuth-209 is bombarded with neutrons.
Polonium in microgram quantities is found in devices that use the ionising effects of alpha particles to remove static electricity. For this, the isotope is electroplated onto foil. Everything we know about polonium suggests that obtaining and administering it must have been a carefully planned operation involving many people and sophisticated technology.
Does anyone have a record of using radiation as a weapon? Yes. In 1993, a Moscow businessman was killed by a lump of radioactive material found in his chair (New Scientist, 11 December 1993, page 6). Also, an investigation into the former East German secret police reported that 鈥渦nusual non-medical X-ray machines鈥� found in buildings used as political prisons could have been used to irradiate inmates (New Scientist, 6 January 2001, p 4). Litvinenko was an outspoken critic of President Vladimir Putin of Russia, who has shown a Stalinist zeal for controlling information by quieting his critics.
None of this, of course, is anything more than circumstantial evidence. One of the best leads the police have is the polonium itself. Isotopes come with contaminants that provide a 鈥渇ingerprint鈥� of their origin, and identifying that fingerprint would be a big step forward. Sources in Moscow say that Russia is being 鈥渟et up鈥�. If that is true, Moscow will be keen to cooperate with British police.
This was a callous, sadistic act. It took Litvinenko three weeks to die, sometimes in extreme pain. Whoever the perpetrators are, they need to be caught.
