Polonium 101: What is it, and why is it so dangerous?

Swiss scientists said they found high amounts of the radioactive element in Yasser Arafat's remains, fueling speculation that the Palestinian leader was killed via polonium poisoning.

Denis Balibouse/Reuters
Analysis of results on research conducted on the remains of Palestinian leader Yasser Arafat, is displayed on a screen during a news conference at the Lausanne University Hospital in Lausanne, Switzerland, on Thursday.

A Swiss forensic team found traces of radioactive polonium in the body of the former Palestinian leader Yasser Arafat, reigniting speculation that the controversial leader may have been brought down by one of his many enemies. Arafat died in 2004 in a Paris hospital, and although allegations of foul play began to swirl immediately, the causes of his death was never officially stated.

Scientists exhumed Arafat’s body from the West Bank city of Ramallah a year ago to take new samples. The team, which included the Lausanne University Hospital’s Institute of Radiation Physics, ran a battery of tests on the samples to conclude: “the results moderately support the proposition that the death [of Yasser Arafat] was the consequence of poisoning with polonium-210.”

This tentative conclusion adds credence to the long-percolating claims of Arafat’s family and allies that he had died of radioactive poisoning. But what is polonium and is there a way to answer with certainty if it was the cause of death? 

What is polonium?

Polonium is a radioactive element discovered in 1898 by scientists Marie and Pierre Curie and named for Marie’s native country, Poland. One of the Earth’s rarest elements, it’s an odorless, silvery-gray soft metal that can be ground into powder.

How deadly is it?

Even a minuscule amount of polonium can be lethal. Radioactive poisoning occurs through eating or drinking contaminated food or through an open wound. The substance poses little danger until ingested, but once it enters the bloodstream it wreaks havoc on bodily tissues and organs, causing a painful deterioration that’s nearly impossible to reverse. 

Signs of poisoning include nausea, vomiting, fatigue, diarrhea, and kidney and liver failure – all of them symptoms Mr. Arafat experienced over the two weeks he was treated in a private Paris hospital prior to his death – as well as hair loss and a weakened immune system.

How difficult is it to obtain?

For someone without access to a nuclear facility, obtaining enough polonium to administer a lethal doze of poison is nearly impossible. Polonium can occur naturally in the earth’s crust, but it is present in extremely low concentrations. It can also be artificially manufactured in a nuclear reactor. Polonium-210, the most common isotope that is now suspected of poisoning Arafat, has a number of industrial uses: reducing static electricity in industrial devices, photographic plates, and even as a heat source for Russian-made lunar landers.

But once obtained, polonium is easy to transport undetected across borders because it does not set off common radiation detectors and is generally non-poisonous as long as it remains outside the human body. 

Are there known cases of death from polonium poisoning?

The most well-known victim of the radioactive element, and one whose death was definitively traced to it, was ex-KGB agent and Kremlin critic Alexander Litvinenko. Mr. Litvinenko fell ill several hours after drinking polonium-laced tea in a London hotel with two Russian companions and died three weeks later in November 2006. Investigators found traces of polonium in the hotel bar and kitchen (with skyrocketing levels registering on the tea pot) as well as in the hotel room occupied by one of Litvinenko’s Russian tea companions on that fateful day.

Can polonium poisoning be proven definitively? 

Polonium decays very quickly (its half-life is 138 days), making it hard to detect and conclusively prove as a cause of death. Its presence in a human body is also very difficult to detect unless scientists are specifically searching for it. Investigators found traces of polonium on Arafat’s body and grave site to be 18 times higher than normal. But even in this case, achieving complete certainty may be impossible since such a long time – eight years – passed between Arafat’s death and the time the samples were collected. 

The Institute of Radiation Physics, a key member of the scientific team, stressed in a press release that despite the team’s preliminary findings, Arafat’s death from polonium poisoning remained merely “a possibility and definitely not a certainty.”

Investigative teams from France and Russia, who had also collected samples in November 2012, have yet to release their findings. 

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