Studies show that Arafat's symptoms fit with the known pattern of Po210 absorption [Getty Images]
Polonium 210 is so toxic that it is difficult to
explain just how dangerous it is - a fatal dose is almost a million
times less than is needed for cyanide, for example.
Its danger comes from its high radioactivity. It decays by giving out
alpha radiation and once Po210 is absorbed and is circulating in the
body, it silently and fatally damages each individual cell. Half of any
amount of Po210 decays in this way every 138 days.
It is impossible to physically see what would be a fatal amount of
solid polonium, making it impossible for anyone to detect that they have
been given the poison. Obviously, this also makes it remarkably easy to
give to someone in a drink or food.
Strangely though, it is completely safe to handle, because alpha
radiation is stopped by even a sheet of paper or by human skin. It can
be carried around in a test tube for years without harming anyone, until
it gets into someone's blood stream.
I believe it did get into Yasser Arafat's bloodstream and here is why.
Evidential certainty
The Swiss scientists produced a truly excellent report, which has
researched every issue and explored every possibility. Their conclusion
about the cause of Arafat's death is based, quite correctly, entirely on
their scientific results, since they have no scientific information
about his illness.
They do comment that his symptoms fit with the known pattern of Po210
absorption, which means it is likely to initially cause damage to the
intestine and lead to related symptoms.
Forensic science as presented to a court, however, always has to consider scientific results in context.
In the case of Arafat, the context of his death is what changes their
scientific assessment of up to 83 percent probability into an evidential
certainty.
To start with, a key question is: How likely are we to find these
levels - a lethal level according to the Swiss - of polonium in someone
who did not die from polonium poisoning?
We have some scientific data on this. There are many bone samples of
people who died naturally which have been analysed over the years, and
they average out at between 25-50 milibecquerels (mBq) per gram of
calcium.
Arafat's ribs were around 900 mBq. That is 18 to 36 times more than
the average, even at the time of exhumation. And remember, that took
place over eight years later when the Po210 had been reduced by 21
half-lives.
So at the time of his death in 2004, he had over two million times
that level circulating in his blood and being deposited in his bones.
And the pattern of the results in the clothing stains done in 2012
and the bones from the exhumation show that the polonium must have been
circulating in him before death. It is only found in actual stains from
his urine, his blood and his sweat, and is highest in those bones which
have the greatest blood supply.
Cause of death
The results in 2012 also show that the Po210 had been manufactured in
a nuclear reactor. That means it could not have come from natural
sources like the decay of radon. The tiny background level of Po210
decay of radon produces in humans has been well established by work in
the nuclear industry.
Just consider how many people have died naturally in the whole world
since 1950. Only five are known to have died from Po210. We can work out
how likely it is that anyone at all would die of Po210 poisoning. And
it is one chance in many billions.
So what are the odds that any person would just happen to have a fatal level in his tissues if he did not die of it?
The fact that Arafat has a level which would have been way into the
accepted lethal range when he died in 2004, now 22 half-lives ago, is
beyond dispute from the Swiss results in their report. And he shouldn't
have had any reactor-produced Po210 in him anyway.
Toxicologists in general and the Swiss scientists in particular, can
never state just from the science that someone definitely has died of,
for example, cyanide or strychnine. That is because the person might
have then jumped off a bridge, or died under a train, so death due to a
poison always depends also on the absence of any other cause being
present.
I am sure the Swiss also considered that although he must have had
high levels of Po210 within the lethal range, he could have become ill
by coincidence from some other unrelated cause. However, very exhaustive
tests were performed by the French Percy Hospital during his final
days, without result. Arafat had no other disease, no cancer, and no
heart disease.
|
From death statistics, the chance of this happening accidentally must
be less than one in several billions for any individual living on this
planet, and maybe even smaller for Yasser Arafat since his food and
drink supply was apparently controlled. |
Questions for judge and jury
In my opinion, this evidential assessment would convince any investigator or member of a jury.
We can summarise just a few of the arguments by anticipating how the
courts would assess the evidence. A court would have to ask four
important questions to assess the significance of the results:
1. Are we satisfied that the results are scientifically correct, and represent levels circulating in life?
We are because the Swiss lab is excellent and their analyses are
comprehensive; and because there is the conclusive pattern of results on
clothing and bone, so the Po210 results could not have been
manufactured by anyone after death.
2. How likely are we to find these levels of Po210 in any other
person in the world, chosen at random, who has died in the last 50
years?
It works out at less than one chance in several billions, even taking
the conservative view that some Po210 accidents may have gone
unreported.
3. How likely is it that these levels are not directly associated with an illness/death occurring in 2004?
A conservative estimate might be 1 chance in 50 or so, even if we do
not take into account what the levels must have been in 2004 - which
would be over 2 million times higher. However, he had no other obvious
cause of death.
4. Is there evidence that the levels present in 2004 would directly cause serious harm?
There is. The Swiss scientists also calculated how much should remain
in his bones in 2013 of a dose in the accepted lethal range that would
have been given in 2004. It fits very well with the figures they
actually obtained from his bones after exhumation.
Absolute certainty
Taking the measured scientific figures obtained by the Swiss,
together with the context, we can be absolutely certain that Arafat
ingested a large dose of Po210, which was made in a nuclear reactor, and
it was circulating in him during his terminal illness.
From death statistics, the chance of this happening accidentally must
be less than one in several billions for any individual living on this
planet, and maybe even smaller for Arafat since his food and drink
supply was apparently controlled.
We are less certain, scientifically, that the calculated levels of
Po210 caused his illness and death simply because the lethal dose is
less well established; but as forensic scientists, we are obliged to
take into account the context, including the fact that he had no other
obvious cause of death.
And of course neither he, nor any of us, would have any reactor-made
Po210 in our blood anyway. That fact alone would satisfy most juries
that something really sinister was going on in 2004.
So, based on my decades of experience and the evidence before me, I
have no evidential doubt that a lethal dose of Po210 was administered to
or ingested by Arafat in 2004, and that it caused his death.
David Barclay is a veteran forensic investigator who
specialises in the assessment of physical evidence in murder cases. He
is also Professor Emeritus at Robert Gordon University, Aberdeen.
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.
SOURCE: AL JAZEERA
