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Our final poisoning case in this lecture
is
a little bit different from all the
others.
It concerns the Russian, Alexander
Litvinenko, who died of poisoning in 2006.
So, if we look back at Litvinenko's
career, he'd started out as an
officer in the KGB and stayed on when the
KGB converted into the FSB.
By 1998, he had become a serious critic of
the Russian government,
and a couple of years later, he sought
asylum in London,
where he continued to be a critic of the
Russian government.
After six years in London, he became
seriously ill
and he died in hospital.
You can see from the picture that one of
the symptoms of his illness is hair loss,
so of course, it was thought that probably
this was thallium poisoning.
But when he was analyzed, for instance,
analysis
of his urine, there was no thallium
detected.
And it turned out that he was being
poisoned in a
very, very unusual way, for which there was
no known precedent.
And that is, he was being poisoned with
Polonium-210.
Now, polonium is a radioactive element.
All forms of polonium are radioactive.
Polonium only occurs naturally in very
trace amounts.
So polonium is actually manufactured in
nuclear reactors.
One of the few places that manufactures
polonium-210 is in Russia.
Now, Polonium-210 is radioactive.
The atoms of Polonium-210 decay to become
Lead-206,
and in the process of decay they emit an
alpha particle, that is,
a radioactive particle is spat out of the
atomic nucleus.
Now, alpha particles are not really that
dangerous,
they will only travel for a few
centimetres in air.
They will only travel for a few
micrometres through the skin.
So, Polonium-210 itself is not very
dangerous provided it's contained,
but if it is ingested, it's very, very
dangerous indeed.
Because if Polonium-210 is ingested, there
is no barrier between
these unstable radioactive atoms and your
biochemical molecules.
So when these atoms decay and they
give out that alpha particle, that alpha
particle
will smash into important molecules in
your
body, your enzymes, your molecular
structures, your DNA.
So it's not like the other poisoning
cases that we've talked about before,
this is radioactive atoms attacking your
molecular structure.
So, nothing could be done,
and Alexander Litvinenko died in hospital
of radiation poisoning.
The thing about radiation is that it is
very characteristic.
The energy of these alpha particles
given out by Polonium-210 is highly
characteristic.
Other radioactive atoms that give out
alpha particles will give out
alpha particles with different energies,
so it's very easy to trace
the Polonium-210 and to confirm that it is
Polonium-210.
So, as the police followed the trail of
Alexander Litvinenko around London, they
were able to find
more than 30 locations where there's
Polonium-210, including
the places where Litvinenko had lunch and
had tea.
And it's believed that the polonium was
put into
his food or drink at one of these
locations.
They were also able to trace Polonium-210
on two British Airways
planes, in fact, they could track it to
the particular seat on the
plane, and these planes were flying on the
London to Moscow route.
So the Metropolitan Police have a suspect
in mind,
someone who they would like to have help
them with their inquiries,
but forensic science can only do too much.
It's now part of international politics.
It's a question of whether the Russians
will arrange
for this person to ever come to London for
questioning.
Well, this concludes our lecture on
toxicology
and we've covered a lot of ground.
We've talked about all sorts of different
poisons,
from plant poisons to carbon monoxide to
inorganic poisons.
We've seen some of the different modes of
actions that these poisons can have, and
how important it is to consider the route
of administration for a particular poison.
We've seen the use of the LD50 value to
measure how strong a poison is.
We've seen how important it is that you
keep your
liver in good health to protect you from
xenobiotic molecules.
We had a quick look at alcohol, the most
common poison.
We've talked about Paracelsus, and then
we've seen the action of some
specific poisons, such as arsenic,
thallium, sarin and atropine.
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