The first four reports here are from 1) Chemistry World, the most technical, 2) Nature, 3) The Independent and 4) BBC news. Thanks to David Turner for providing the links. The last, 5) is a blog on polonium-210 poisoning by Deborah Blum, written a year ago, which is helpful to non-scientists.
Diagram showing the effects of polonium poisoning, as known at the time (2012).
By Anthony King, Chemistry World, Royal Society of Chemistry
November 13, 2013
The investigation into whether or not the former Palestinian leader Yasser Arafat was poisoned with a radioactive isotope of polonium almost ran out of time. As it is, eight years after his death the amount of polonium found by Swiss investigators in most samples from his grave are small and ambiguous, thanks to the decay of the radionuclide. Nonetheless, the available evidence has led them to conclude that their results ‘moderately support the proposition that the death was the consequence of poisoning with polonium’.
Arafat took ill suddenly on the evening of 12 October 2004 with severe nausea, vomiting and stomach cramps. He died one month later at a French military hospital, yet his illness remained a mystery. There was no autopsy and no biological samples left for tests.
Scientists investigating Arafat’s death previously found polonium traces when they analysed his personal belongings. The garment with the most polonium-210 – urine-stained underwear – had up to 40 times the background level of the radionuclide.
The only confirmed poisoning using polonium-210 was that of Russian dissident Alexander Litvinenko in London in November 2006. He is believed to have ingested a quantity of the isotope with an activity of 1–3GBq. His death triggered a rethink of the Arafat case. The Swiss team now estimate that if Arafat swallowed a quantity of polonium-210 with an activity of 1GBq in October 2004, this would roughly tally with the 181mBq they found on his underwear.
The unexplained polonium-210 on Arafat’s personal effects led to the opening of his tomb last November. Russian, French and Swiss investigators took samples from his body, shroud and surrounding soil. The report from the University Centre of Legal Medicine in Switzerland was posted last week by Al Jazeera. The French and Russian teams have yet to report publicly.
The Swiss team measured polonium-210 levels using α-spectrometry to detect a distinct energy signature at 5.3MeV. This tell-tale signal indicates the presence of α-particles – two protons and two neutrons – ejected when polonium-210 decays to lead-206, a stable isotope. They also measured how much lead-210 was present using γ-spectroscopy.
Polonium-210 occurs naturally, however, and the scientists had to try to compensate for this. Naturally occurring uranium-238 goes through a decay chain to produce lead-210, which decays to bismuth-210 and this rapidly yields polonium-210. Lead and polonium isotopes reach a predictable state of equilibrium in nature. However, synthetic polonium-210 made by irradiating bismuth-209 with neutrons has lower levels of lead-210, which marks it out as man-made or unsupported.
Many of the bone samples also had suspicious levels of polonium-210, with tests on a rib discovering it had 18 times the background level of the isotope. Tissue surrounding bones was twice as radioactive as the reference soil and shroud specimens. The report also noted that lead-210 in the bones and soft tissues were up to 20 times greater than expected. ‘Unsupported polonium in the personal belongings is compatible with artificial polonium,’ notes report author François Bochud. ‘In the grave samples, polonium appeared to be supported [or from natural sources]. But the quantity of lead-210 was significantly higher than the reference values.’
The Swiss team theorise that traces of polonium-210 were masked by impurities of lead-210 in a putative poison dose. This is backed up by their discovery of lead-210 contamination in a commercial sample of polonium-210. ‘Polonium is a “soft-tissue seeker” and lead is about 10 times more likely to end up in bones than polonium,’ Bochud says. ‘Furthermore, we measured the personal belongings almost one year before the bones and polonium decays much faster than lead-210. Unsupported polonium was therefore more likely to be measurable in the personal belongings. On the other hand, lead-210 in bones was more likely to be present in higher quantities and therefore hide the potential presence of unsupported polonium.’
Paddy Regan, a nuclear physicist at the University of Surrey, UK, praises the report as thorough. He adds that they’ve measured the isotopes accurately, reported their results honestly and got a few samples with unexplained polonium-210. As a result he says that foul play can’t be ruled out in Arafat’s death.
Regan is, however, circumspect about the high levels of polonium widely reported in Arafat’s rib. ‘Samples were very small, less than a gram, and you can get variations on an order of magnitude in the natural environment,’ he notes. ‘It’s not that they measured 100 samples and found 18 times higher activity than the background in each of them.’ He also notes that in some bones they discovered more lead-210 than polonium-210, which he suggests might be a sample extraction artefact.
He adds that these findings should be approached with caution. ‘More than 20 half-lives have passed since Mr Arafat’s death and the analysis of his remains,’ Regan says. ‘If you do the sums you get much less than one part per million of any original polonium, so unless you had a huge initial dose, it would be down to a level that would be pretty close to what you expect to see as normal background.’ He says if measurements had been done three years ago, the expected radiation levels if he had been poisoned would be hundreds of times what they are now and the Swiss team would have been in a position to make a much stronger statement. No further radiological evidence is likely to emerge and investigators will need to follow other leads now if they are to solve the mystery.
Investigation claims evidence of polonium poisoning in death of Palestinian leader but draws no certain conclusions.
By Mark Peplow, Nature
November 07, 2013
Tests on the exhumed body of the late Palestinian leader Yasser Arafat have found traces of the radioactive isotope polonium-210, prompting renewed claims that he was deliberately poisoned.
“The results could reasonably support the proposition that the death was the consequence of poisoning by polonium-210,” says Patrice Mangin, director of the University Centre of Legal Medicine in Lausanne, Switzerland, who led the analysis.
But his lengthy report on the investigations, released yesterday (PDF), is clear that the evidence offers no firm conclusions. “I don’t think it will settle the debate,” says Patrick Regan, a nuclear physicist at the University of Surrey, UK.
Arafat died in a Paris hospital on 11 November 2004 after a month of ill health that included symptoms such as abdominal pain and vomiting. No autopsy was conducted, allowing rampant speculation about the cause of his death. In 2011, news broadcaster Al Jazeera obtained personal belongings that Arafat had used shortly before his death, including a toothbrush and clothing, and commissioned the Lausanne team to investigate.
Former KGB officer Alexander Litvinenko was killed by polonium-210 poisoning in 2006, and the case inspired the Lausanne team to hunt for the same isotope in Arafat’s effects. Polonium-210 emits α-particles that rip cells apart like a wrecking ball, destroying a person’s immune system and causing catastrophic organ failure.
To their surprise, the researchers found polonium-2101. A piece of Arafat’s underwear stained with urine had a radioactivity of 181 millibecquerels, almost 100 times higher than normal background levels (see ‘Was Yasser Arafat killed by polonium?’). This prompted a French murder investigation, and his body was exhumed on 27 November 2012. Investigators took samples from his bones, burial shroud and the soil from around the grave.
Mangin’s team scoured the samples for the characteristic energy signature of polonium-210’s α-particles. But they also measured other isotopes that would reveal whether that polonium-210 was from a natural or a synthetic source.
Naturally occurring radon-222 decays to give a long chain of daughter products, including lead-210 and subsequently polonium-210, which our bodies contain in trace amounts. Roughly two years after death, those isotopes would normally reach equilibrium, so that they emit the same amounts of radiation. But synthetic polonium-210 is made by irradiating bismuth-209 with neutrons, and should contain no lead-210. If Arafat had been poisoned, “a significant enhancement of polonium-210 compared to lead-210 would be a smoking gun”, says Regan.
The results were mixed. Some samples showed unusually high levels of the isotopes — but in many cases their radioactivity was fairly evenly matched. Some even had much more lead-210 than polonium-210, suggesting that the isotopes had been extracted from bone samples at different rates, further muddying the data. There is certainly no smoking gun in the report, says Regan.
One explanation for the matching isotope ratios could be that Arafat was given a dose of polonium-210 contaminated with lead-210. Although most of the polonium would have decayed by now, lead-210 has a half-life of 22 years, so its radioactivity would barely have declined since Arafat’s death. The Lausanne scientists tested a commercial sample, and found that it did contain enough lead-210 to account for the high levels in Araft’s tissues. “It’s a plausible hypothesis,” says Regan.
They also saw elevated levels of a polonium-210 decay product, lead-206, in some samples, providing further evidence that Arafat died with high levels of polonium-210 in his body. Although the analysis cannot prove foul play, “one doesn’t absorb by accident, or voluntarily, a source of polonium”, says François Bochud, a colleague of Mangin’s and co-author of the report. “From the moment one considers that the polonium was introduced artificially in the organism, that necessarily implies the intervention of a third party.”
Others are less certain. Polonium-210 has a half-life of 138 days, so any radioactivity measured by the team would have been a million times lower than in 2004. “After so many half-lives, you can’t reliably say how much polonium was there eight years ago, there’s too much background interference,” says Kai Vetter, head of applied nuclear physics at the Lawrence Berkeley National Laboratory in California. Vetter suggests that the team should survey other commercial polonium samples to back up their lead-contamination hypothesis, and re-check the methods they used to extract the isotopes from tissue for systematic errors.
Meanwhile, two other teams, in France and Russia, have received tissue samples, but have yet to report their results. Until then, says Vetter, the Lausanne analysis simply raises more questions about Arafat’s mysterious death.
British expert says it’s ‘highly unlikely’ Arafat was poisoned
Symptoms are very different from those of the Russian dissident Alexander Litvinenko, says Professor Nicholas Priest
By Paul Martin, The Independent
November 08, 2013
A leading British biomedical scientist says it is “highly unlikely” that former Palestinian leader Yasser Arafat died in a French hospital in 2004 from a lethal dose of radioactive polonium.
Reports that samples taken from Arafat’s interred body and analysed by a Swiss laboratory showed high levels of the substance have led to Arafat’s widow calling his death “the crime of the century”. It has also stimulated public outrage among Palestinians, who generally consider Israel to be the most likely perpetrator, though Arafat had many internal enemies.
Speaking in Ramallah yesterday Tawfik Tirawi, who heads the Palestinian committee investigating the death, said that Israel is the “first, fundamental and only suspect,” in the case.
Researchers had hoped to find answers when they analysed samples taken from Arafat’s grave in November last year and handed to laboratories in Switzerland, Russia and France. Their report earlier this week concluded that they are confident up to an 83 per cent level that the Palestinian leader was poisoned.
However Professor Nicholas Priest, who formerly headed the biomedical research unit of the Atomic Energy Authority in Britain, told The Independent that, while poisoning by polonium “cannot be totally ruled out”, the symptoms were very different from those of the Russian dissident Alexander Litvinenko, who died in London in 2006. The professor, a specialist in radiation toxicology, is one the few British scientists to have worked with polonium-210. He was involved in the research over Mr Litvinenko’s death – the only known case of fatal poisoning by the substance. “Key indicators it was not polonium [that killed Arafat] were lack of hair loss in the face, and no damage to his bone marrow, both of which were found extensively in Litvinenko,” Professor Priest said. Photographs show Arafat stepping into a helicopter on the way to France sporting a white beard, while pictures of Litvinenko in hospital reveal an absence of any hair.
He pointed out that polonium would be naturally produced in the bones of anyone buried as a by-product of the bones absorbing lead from the soil, a point, he said, that “the authors of the report understand but the journalists do not”. The Swiss researchers’ carefully worded report admits that even in the tiny samples of non-bone body remains it found in the grave “no significant amount of unsupported polonium-210 was measured”. They also admit that the pattern of Arafat’s illness was “not consistent with typical acute radiation syndrome”.
Professor Priest said it was “far too dangerous and scientifically unjustified” to calculate how much polonium was in Arafat’s body on the basis of “such tiny concentrations of polonium”. He explained: “The amount found was about one thousandth of a Bq [becquerel] per gram, and if you multiply it back up to what it might have been eight years earlier (doubling the concentration each 138 days), you get a figure of 192 million Bq administered.”
By BBC news
November 06, 2013
The late Palestinian leader Yasser Arafat may have been poisoned with radioactive polonium, says a Swiss forensic report obtained by al-Jazeera.
Arafat’s official medical records say he died in 2004 from a stroke resulting from a blood disorder.
But his body was exhumed last year amid continuing claims he was murdered.
The Swiss report said tests on the body showed “unexpected high activity” of polonium, which “moderately” supported the poisoning theory.
Many Palestinians have long believed that Israel poisoned Arafat. There have also been allegations that he had Aids or cancer. Israel has consistently denied any involvement.
A spokesman for the Israeli foreign ministry said the Swiss investigation was “more soap opera than science”.
‘Hole in theory’
The scientists – from the Vaudois University Hospital Centre (CHUV) in Lausanne, Switzerland – carried out a detailed examination of Arafat’s medical records, samples taken from his remains and items he had taken into the hospital in Paris where he died in 2004.
The biological materials included pieces of Mr Arafat’s bones and soil samples from around his corpse.
The scientists concluded that their results “moderately support the proposition that the death was the consequence of poisoning with polonium-210”.
The scientists stressed that they had been unable to reach a more definitive conclusion because of the time that had lapsed since Arafat’s death, the limited samples available and the confused “chain of custody” of some of the specimens.
Polonium-210 is a highly radioactive substance. It is found naturally in low doses in food and in the body, but can be fatal if ingested in high doses.
The scientists have made “a pretty strong statement”, according to Prof Paddy Regan, an expert in radiation detection and measurement at the University of Surrey in the UK, who was not involved in the investigation.
“They are saying the hypothesis that Arafat was poisoned with polonium-210 is valid and has not been disproven by the data. However they cannot say definitively that he was murdered.”
Prof Regan says a series of assumptions would have been made in order to ascertain how much Po-210 may or may not have been in Mr Arafat’s body at the time of his death.
Po-210 has a short half-life of about 138 days.
Prof Regan said measuring the tiny fraction left and extrapolating it back to the time of Arafat’s death was like a blind man holding the tail of an elephant and using the information to work out the size of the animal.
The second problem, he said, was that Po-210 occurs naturally in the environment. However, an indicator that the polonium may be synthetic is if there was far less Pb-210 (lead-210) in the samples.
The professor highlighted results from two samples – the shroud under the corpse of Mr Arafat and urine samples taken from his underwear – both showed high levels of Po-210 compared to Pb-210, possibly suggesting the presence of “additional” synthetic polonium.
He noted however that most of the samples of polonium measured in the report were accompanied by activities from Pb-210.
Parallel investigations are being carried out by French and Russian experts – one Russian official said last month that no traces of polonium had been found.
Yigal Palmor of Israel’s foreign ministry told the BBC: “This is more soap opera than science.”
He said the investigations had been commissioned by “interested parties” – Mr Arafat’s widow and the Palestinian Authority – and had “never bothered” to look for some key data.
“The other huge hole in the theory is the absence of all access to the French hospital where Arafat died and to Arafat’s medical files,” said Mr Palmor.
“How can the cause of death be determined without the opinion of the doctors or the results of the medical tests they ran on the patient?
“Israel doesn’t feel concerned in the least.”
Speaking in Paris, Arafat’s widow, Suha, said the Swiss results revealed “a real crime, a political assassination”.
“This has confirmed all our doubts. It is scientifically proved that he didn’t die a natural death and we have scientific proof that this man was killed.”
Reuters said she did not name any suspects and acknowledged that her husband had had many enemies in his lifetime.
Arafat, who led the Palestine Liberation Organisation for 35 years and became the first president of the Palestinian Authority in 1996, fell violently ill in October 2004 at his compound.
Two weeks later he was flown to a French military hospital in Paris, where he died on 11 November 2004, aged 75.
France began a murder inquiry in August 2012 after the Lausanne scientists, working with an al-Jazeera documentary crew, found traces of polonium-210 on Arafat’s personal effects.
His widow had objected to a post-mortem at the time of his death, but asked the Palestinian Authority to permit the exhumation “to reveal the truth”.
His remains were removed from his tomb in the West Bank city of Ramallah in November 2012 and reinterred the same day.
Last month, the head of the Russian Federal Medico-Biological Agency, Vladimir Uiba, was quoted by the Interfax news agency as saying that Arafat “could not have been poisoned with polonium”, saying that test carried out by Russian experts “found no traces of this substance”.
However, the agency later denied that Mr Uiba had made any official statement on the findings.
The head of the Palestinian investigation team, Tawfiq Tirawi, confirmed on Tuesday that the Russian and Swiss reports had been delivered. The Palestinian team is reported to have handed over its findings on Saturday.
By Deborah Blum, Wired Science blog
November 27, 2012
I first wrote about Yasser Arafat and polonium-210 this summer when traces of the radioactive element were found in the personal effects of the dead former Palestinian leader. As his body was exhumed earlier today to look for more conclusive evidence of poisoning, the following is an update of that post.
In the late 19th century, a then-unknown chemistry student named Marie Curie was searching for a thesis subject. With encouragement from her husband, Pierre, she decided to study the strange energy released by uranium ores, a sizzle of power far greater than uranium alone could explain.
The results of that study are today among the most famous in the history of science. The Curies discovered not one but two new radioactive elements in their slurry of material (and Marie invented the word radioactivity to help explain them). One was the glowing element radium. The other, which burned brighter and briefer, she named after her home country of Poland — Polonium (from the Latin root, polonia). In honor of that discovery, the Curies shared the 1903 Nobel Prize in physics with their French colleague Henri Becquerel for his work with uranium.
Radium was always Marie Curie’s first love – “radium, my beautiful radium,” she used to call it. Her continued focus gained her a second Nobel Prize in chemistry in 1911. (Her Nobel lecture was titled Radium and New Concepts in Chemistry.) It was also the higher-profile radium — embraced in a host of medical, industrial, and military uses — that first called attention to the health risks of radioactive elements. I’ve told some of that story here before in a look at the deaths and illnesses suffered by the “Radium Girls,” young women who in the 1920s painted watch-dial faces with radium-based luminous paint.
Polonium remained the unstable, mostly ignored step-child element of the story, less famous, less interesting, less useful than Curie’s beautiful radium. Until the last few years, that is. Until the reported 2006 assassination by polonium 210 of Russian spy turned dissident, Alexander Litveninko. And until the news, first reported by Al Jazeera in July, that a Swiss laboratory had detected surprisingly high levels of polonium-210 in the clothes and other effects of the late Palestinian leader Yasser Arafat.
Arafat, 75, had been held for almost two years under an Israeli form of house arrest when he died in 2004 of a sudden wasting illness. His rapid deterioration led to a welter of conspiracy theories that he’d been poisoned, some accusing his political rivals and many more accusing Israel, which has steadfastly denied any such plot.
Recently (and for undisclosed reasons) his widow agreed to the forensic analysis of articles including clothes, a toothbrush, bed sheets, and his favorite kaffiyeh. Al Jazeera arranged for the analysis and took the materials to Europe for further study. After the University of Lausanne’s Institute of Radiation Physics released the findings, Suha Arafat asked that her husband’s body be exhumed and tested for polonium.
The exhumation was authorized by Mahmoud Abbas, president of the Palestinian Authority, and that order was carried out this morning. Reportedly 20 tissue samples were taken from the eight-year-old remains and will be turned over to independent laboratories in France, Switzerland, and Russia. According to The Washington Post, the laboratories are expected to include a broader toxicology analysis as well. Results are not expected for several months.
And at this point, as we anticipate those results, it’s worth asking some questions about polonium-210 and about the mysteries surrounding this particular death. We might starting with wondering why a killer would pick a poison that might leave a trail of evidence behind. In the case of the Radium Girls, scientists found that their bones were still hissing with radiation years after their deaths. In the case of Litvinenko, public-health investigators found that he’d literally left a trail of radioactive residues across London where he was living at the time of his death.
But this story is different and most of that has to do with time – and timing. Radium has a half-life of about 1,600 years. But polonium-210 is far less stable; it has a half-life of 138 days. Half-life refers to the time it takes for a radioactive element to burn through its energy supply, essentially the time it takes for activity to decrease by half. For comparison, the half life of the uranium isotope U-235, which often features in weapon design, is 700 million years. In other words, polonium is a little blast furnace of radioactive energy.
To understand that difference, it helps to begin by stepping back to some of the details provided in the Curies’ seminal work. Both radium and polonium are links in a chain of radioactive decay (element changes due to particle emission) that begins with uranium. Polonium, which eventually decays to an isotope of lead, is one of the more unstable points in this chain, unstable enough that there are some 33 known variants (isotopes) of the element. The speed of its decay means that eight years after Arafat’s death, it would probably be identified by the its breakdown products rather than the direct radioactive evidence associated with more recent fatalities. And still, the breakdown products remain interesting – and possibly traceable – as an assassin’s weapon.
Like radium, polonium’s radiation is primarily in the form of alpha rays — the emission of alpha particles. Compared to other subatomic particles, alpha particles tend to be high-energy and high-mass. Their relatively larger mass means that they don’t penetrate as well as other forms of radiation; in fact, alpha particles barely penetrate the skin. And they can be stopped from even that by a piece of paper or protective clothing.
That may make them sound safe. It shouldn’t. It should just alert us that these are only really dangerous when they are inside the body. If a material emitting alpha radiation is swallowed or inhaled, there’s nothing benign about it. Scientists realized, for instance, that the reason the Radium Girls died of radiation poisoning was because they were lip-pointing their paintbrushes and swallowing radium-laced paint. The radioactive material deposited in their bones — which literally crumbled. Radium, by the way, has a half-life of about 1,600 years. Which means that it’s not in polonium’s league as an alpha emitter. How bad is this? By mass, polonium-210 is considered to be about 250,000 times more poisonous than hydrogen cyanide. Toxicologists estimate that an amount the size of a grain of salt could be fatal to the average adult.
In other words, a victim would never taste a lethal dose in food or drink. In the case of Litvinenko, investigators believed that he received his dose of polonium-210 in a cup of tea, dosed during a meeting with two Russian agents. (Just as an aside, alpha particles tend not to set off radiation detectors so it’s relatively easy to smuggle from country to country.) Another assassin advantage is that illness comes on gradually, making it hard to pinpoint the event. Yet another advantage is that polonium poisoning is so rare that it’s not part of a standard toxicology screen. In Litvinenko’s case, the poison wasn’t identified until shortly after his death. In Arafat’s case — if polonium-210 killed him and that has not been established — obviously it wasn’t considered at the time. And finally, it gets the job done. “Once absorbed,” notes the U.S. Regulatory Commission, “The alpha radiation can rapidly destroy major organs, DNA and the immune system.”
Many Palestinians have long suggested that Israel is behind Arafat’s death – an accusation that country has repeatedly denied, pointing out that it had nothing to gain from his death. But the presence of polonium intensifies that assassination issue. Why?
One obvious reason is that polonium-210 is not very readily available to the average citizen. It’s a rare element. And a rare industrial product. About 100 grams are produced worldwide annually — and production is both limited and controlled. For instance, the NRC licenses polonium-201 for use in certain static-elimination devices in industry. But the amount allowed is so small that the agency estimates that it would take 30,000 devices to assemble a lethal dose.
The element is most commonly produced through neutron bombardment in nuclear reactors, which again suggests that it’s a product available to a chosen few. Which brings me to an assassin disadvantage — traceability. In the case of the Litvinenko killing, investigators suggested that the polonium isotope found in his body had a chemical signature that indicated production in a Russian nuclear reactor. Such clues, according to Al Jazeera, would be sought in analyzing Arafat’s body: “A conclusive finding that Arafat was poisoned with polonium would not, of course, explained who killed him,” the story concludes. “It is a difficult element to produce, though — it requires a nuclear reactor — and the signature of the polonium-210 in Arafat’s bones could provide some insight about its origin.”
As Patrick Walter points out in an excellent analysis in Chemistry World (published by the Royal Society of Chemistry) modern instruments are capable of detecting polonium breakdown products in incredibly small amounts, even the bare trace that might be found here. But as he also notes, the picture is still complicated. Polonium-210 is, after all, a naturally occurring element and finding evidence of exposure doesn’t necessarily mean evidence of foul play.
And as forensics experts emphasized to the BBC, the years of polonium decay may yet make precise identification of the source impossible. Further, the decay of the body itself is likely to render a clear cause of death portrait equally difficult. As one forensic pathologist noted: ”Trying to interpret what levels of radiation there would have been eight years ago and whether [they were] sufficient to be fatal is going to be very, very difficult.”
Realistically, even if the tests are inconclusive, suspicion will remain. And even if this really were a polonium murder — or let’s say a heartless, government-sanctioned killing — forensics still won’t give away the name of the killer or necessarily the country. But there is that slim possibility that tests could reveal the source of the poison and, as a side-effect, the home of the assassin. It’s that latter whisper of a possibility that makes these eventual results so tantalizing – and, I’d add, a little unnerving.