Lab report

It is difficult to see how a competent assassin would expect the cause of Litvinenko's death to stay unknown. Why was polonium chosen?
January 14, 2007
Why polonium?

Alexander Litvinenko is, as far as I am aware, the first person to have been deliberately poisoned with the radioactive element polonium-210, although ironically one of the element's first casualties was Irène Joliot-Curie (daughter of its discoverer Marie Curie) whose leukaemia was allegedly caused by the explosion of a capsule of polonium in her lab 15 years earlier.

There seem to be only two reasons why a poisoner would choose polonium-210 to do his deadly work: to serve as a calling card—or out of incompetence. Polonium is scarcely the first lethal substance a hospital will test for when investigating a poisoning, since it is so rare and hard to procure. Only about 100g are made every year, by nuclear transmutation conducted in a nuclear reactor. The lethal dose is just a few micrograms.

But polonium-210 is easy enough to identify from its radioactive decay signature once you look for it. The unstable element emits alpha particles, the nuclei of helium atoms. If it is ingested, these particles smash into molecules in the body, initiating fatal damage to cells.

Because alpha particles are so quickly stopped by collisions with other atoms, specialised types of Geiger counter are needed to identify them. Yet polonium-210 was apparently detected during tests for a radioactive form of thallium in Litvinenko's urine. Thallium is a familiar poison, used in pesticides (though banned as such in the west).

It's difficult to see how a competent assassin would expect the cause of Litvinenko's death to stay unknown, and the relatively short half-life of polonium-210 means that the trail is still warm—as it decays quickly, it must have been made quite recently. It seems the Russian reactor where this batch was produced has already been identified, and the radioactivity has left a trail of crumbs that can be followed, via British Airways, back to Moscow. At this rate, it would not be surprising if the culprit was identified by the time Prospect hits the newsstands.

Justifying nuclear fusion

The recent signing—by the EU, the US, Japan, Russia, China, South Korea and India—of an agreement to fund the international nuclear fusion project ITER is in one sense a formality: ITER has been planned for years, and the arguments, at times bitter, over where to situate it have already taken place (the reactor will be constructed in the south of France). But it raises the question of whether investment in fusion research should be regarded as funding of big science, in the same way as the large hadron collider (LHC) at Cern, for example, or as money spent on a sustainable energy programme. Fusion's long-standing reputation as the acceptable, even green, face of nuclear power—it potentially offers far more energy than fission while producing less hazardous waste—is starting to wear thin after decades of investment for no return. (See "The return of nuclear fusion" by Fred Pearce, Prospect July 2006.)

The fusion lobby argues that if any project can crack the nut of harnessing nuclear fusion in a way that releases more energy than it consumes, it will be ITER. The challenge is how to hold what is effectively a piece of the sun without it squirting out of its container. That has proved to be a fascinating source of new physics, and some proponents of ITER are relishing the prospect of getting to grips with the fundamental science. But unlike megabuck projects such as the LHC, ITER's key questions are largely self-referential, and so it would be hard to justify the €5bn price tag on the strength of the physics alone.

That seems a small price for an antidote to global warming, given the estimated bill delivered in the Stern report. But some wonder if the money might not be better spent on developing wind, wave and solar power, or indeed on improving fission power generation. ITER is not expected to be running until 2016 at best, and we may not see commercial fusion power for at least a decade after that. Others forecast no payoff from fusion before 2100. So ITER stands at an uneasy juncture, a high-risk venture not quite able to justify itself on either scientific or pragmatic grounds.


Farewell Sainsbury

The accolades garnered from all quarters by David Sainsbury, who stepped down in November as the British government's science minister, are a fair reflection of a job well done. Whatever one might feel about the propriety of his donations to the Labour party, he has earned the respect of his constituents: Britain's scientists and technologists. Sainsbury leaves science funding looking much healthier than it was when he began his stint eight years ago. Perhaps more significantly in the long run, Britain at last shows signs of developing (some would say rediscovering) a talent for translating innovative academic research into competitive business. The density of technology spin-off companies in the triangle between Oxford, Cambridge and London is said to be the highest in Europe. Among these start-ups are genuine world leaders in new technologies, such as Cambridge Display Technology, which has pioneered the use of "plastic electronics" for making cheap, flexible, lightweight colour displays for television and other devices. Licensing arrangements with Philips, Seiko, Epson and others should guarantee CDT a premier position in this potentially lucrative market. Sainsbury considered such high-tech business clusters a driver of British science, and he deserves credit for creating an environment where they can thrive.