Suspicions about the cause of Yasser Arafat’s death are not new, but an Al Jazeera report published last week detailing the findings of a team of scientists brings new light to the subject. Even though the report itself only “moderately supports” the hypothesis that Mr. Arafat was poisoned by radioactive polonium 210, some forensic scientists, including David Barclay, have called it “a smoking gun.”
Is this an accurate characterization? Unfortunately, no. I have no doubt based on what I read that there were some small amounts of polonium in the samples, as the report indicates. However, the world’s media have leapt to conclusions based on this finding, even though there is ample ambiguity after the passage of so much time.
The thing with detailed reports such as this one is that sometimes it can be revelatory to see what was not explained in the report. Several important concepts are left unexplained and unaddressed. Foremost is the issue of half-life. All radioactive isotopes decay into other elements, and the rate at which they do so is called a “half-life.” For polonium 210, its half-life is about 138.4 days. After one half life, half of the polonium has decayed, after two half lives, a quarter remains, and so on. Around 19 half-lives elapsed between his death and the examination of his personal effects, 21 half-lives with the skeletal remains. This means that, if Mr. Arafat had been poisoned with polonium 210, the percentage of remaining material would be very small, on the order of 0.00004% in the case of the bones.
Another glaring issue with the report is that the units in use are not well explained. The casual reader is not given the context of how big a milliBecquerel (mBq) is. It’s extremely small. Even a Becquerel is a very small unit for measuring radiation sources. (Mega- and even GigaBecquerel are not unusual for describing radiation sources.) Often, these kinds of mBq levels are at the lower detection limit or within the error margin of instruments, although this is not made clear in the report. Even the highest figures noted in the report, in the range of 900 mBq, are actually very small by most standards. It should be noted that much coverage of the report fixates on the single 900 mBq figure, which is the highest, by far, of any of the figures in the report.
Polonium 210 is found in nature as well as occurring as the result of manmade activity. Many of the measurements of the personal effects could easily be within the realm of naturally occurring background levels. As it is a natural decay product from uranium, which is ubiquitous in geology around the world, you will find small amounts of polonium 210 nearly everywhere if you look hard enough. One interesting fact is that polonium 210 is commonly found in tobacco, as tobacco plants absorb uranium from the soil. One Brazilian study found that a single cigarette could easily have as much as 28.9 mBq of polonium 210, although the figures vary widely between brands. Soil contains polonium, which vary widely around the world. As one example, in Norway, the top humus layer of soil can easily contain up to 363 mBq/g, a figure well in excess of many of the figures in the report. Sadly, a similarly detailed report on soil background level in Palestine is not available, so I include this fact as merely as one comparison. In addition, the report shows Radon gas was quite high in the grave, and Polonium is an eventual decay production of the particular isotope of Radon detected.
The Swiss report also makes reference to the issue of “supported” versus “unsupported” polonium 210. The science is complex – as naturally occurring polonium 210 comes from decay of Lead 210. If one measures the Lead 210 in a particular place and compares it to the amount of polonium, mathematical calculations can show if the proportion is correct for the polonium having been caused by decay of the Lead. This is “supported” polonium, and it is much more likely to have come from natural sources rather than nefarious ones. The report clearly states on page 58 that the polonium in the human remains was likely to be “supported.” In my mind this casts some serious doubt on the poisoning hypothesis.
Another huge deficit in the evidence is the chain of custody. This concern is actually voiced in the report itself. The evidence has been out of the control of those examining it for years. There’s no assurance that the personal effects or the human remains were not tampered with in some way between 2004 and 2012. I’m not saying that they were; it is just that it cannot be ruled out. Likewise, it could be possible that Mr. Arafat’s grave could have been tampered with at some point in the intervening years.
The Swiss report fairly states many of these issues if you read it closely enough. But it is by no means a “smoking gun.” Could Mr. Arafat have been poisoned by polonium? Certainly. Is it possible that the evidence could have been tampered with? Yes. Is it possible that much of the polonium detected is from natural sources? Yes. But the passage of time and an eroded chain of custody mean that forensic science done in 2012 faces serious limitations, and we may never be in a position to know for sure.
Dan Kaszeta is a former US Army and US Secret Service specialist on chemical, biological, and radiological defense, now working as an independent consultant based in London.