The body of Yasser Arafat will be exhumed so that tests can determine whether he died after being poisoned with the radioactive metal polonium-210 (see the Guardian).

Arafat was President of the Palestinian National Authority when he died on 11 November 2004, after falling ill about two weeks earlier with what was initially described as flu. His condition deteriorated rapidly, however, and he was transferred to a hospital in France, where he spent his final days in a coma. Despite a plethora of rumours, his death has remained unexplained.

Al Jazeera reported yesterday that tests on Arafat’s personal belongings had found abnormally high levels of polonium-210, the radioactive element used to kill former Russian spy Alexander Litvinenko in 2006. Polonium-210 emits alpha particles that can tear through cells, damaging DNA and causing radiation poisoning. Since alpha particles cannot penetrate skin, polonium has to be ingested to have fatal effects. In Litvinenko, it initially caused vomiting, diarrhoea and weight loss — symptoms that Arafat also experienced.

Al Jazeera had approached the Institute of Radiation Physics in Lausanne, Switzerland, on behalf of Arafat’s widow, Suha, who provided various items of her husband’s clothing and other effects for analysis.

François Bochud, director of the institute, told Nature that he did not expect to find any polonium in these items. But “we looked for it because of Litvinenko”, he says.

The scientists mixed samples of cloth with a solvent to extract any lingering radioisotopes. They washed this solution on to a silver disc, which absorbs the isotopes, and tested it using alpha-particle spectroscopy. They also conducted control experiments using items of Arafat’s clothing that he had not worn after falling ill.

A sample of urine-stained underwear showed polonium-210 radioactivity of 180 millibecquerels (mBq) — roughly one radioactive decay every 5 seconds. A control sample had a radioactivity of about 10 mBq. Bochud says that naturally occurring polonium-210 — resulting from the decay of radon gas, for example — normally causes a radioactivity of about 5 mBq per litre of urine.

Polonium-210 has a half-life of about 138 days, so about 20 half-lives had passed between Arafat’s death and the testing in Lausanne. This means that the amount of polonium in the samples — and in Arafat’s body — would have been about a million times greater when he died. Bochud and his colleagues calculated that Arafat would have had similar levels of polonium-210 in his body as Litvinenko.

So was Arafat poisoned? “We can’t conclude this,” says Bochud, although he adds that he is “50% sure”. It is conceivable that some external contamination could have caused the results they saw, he says.

The scientists ran their first set of tests in February, and then repeated them three months later to measure how much the polonium radioactivity had changed. This was one way of assessing whether the polonium was being produced by the decay of lead-210, another naturally occurring radioisotope with a longer half-life, of more than 22 years. Yet the polonium radioactivity had tailed off in a way that was consistent with the majority of it having been introduced directly into Arafat’s body, rather than being produced by a parent isotope, says Bochud.

Bochud adds that no further information could be gleaned from the samples they have. “Our only suggestion,” he says, “is to exhume the body and measure the radioactivity.” It now seems that those tests will go ahead, and could solve the mystery of Arafat’s death once and for all.