Poisonous trail radiates worldwide

A HIGHLY sophisticated poison was how Klaus Leutzenkirchen, the head of the nuclear chemistry department in the EU’s Institute for Trans-uranium elements, described polonium-210.

British police believe an infinitesimal amount of this radioactive substance was used to kill Alexander Litvinenko, the former Russian spy who defected and had recently become a British citizen.

Scotland Yard is working overtime trying to trace the trail of the poison, as it is their best chance of finding the killer. So far it has led them to Moscow, Italy and the US.

But investigations so far into who might have been responsible for the audacious killing are throwing up stories that are getting increasingly murky.

They range from Russian President Vladimir Putin to smaller oligarchs and involve stings and counter-stings and even attempts to smear Italian Prime Minister Romano Prodi by his rival Silvio Berlusconi.

With every passing day, however, the trail is getting colder as the main evidence — the polonium-210 — becomes less radioactive and spreads ever wider as more people come in contact with its remains.

The job requires not just police but specialists in this area of radioactive substances, in which there is a thriving black market worldwide, involving legitimate governments and terrorists.

The Institute for Transuranium Elements is one such specialist agency that carries out this kind of detective work as part of the EU’s Joint Research Centre. It works to identify any nuclear material seized by police or security forces in Europe, trying to gauge where it has come from and for where it was destined.

One of its other jobs is to make sure nuclear materials in Europe’s laboratories, hospitals and nuclear reactors and reprocessing plants like Sellafield do not go missing. This frequently means working with the International Atomic Energy Agency (IAEA).

Dr Leutzenkirchen explains that polonium is relatively safe to carry around, so the poisoner need not be in danger from the radioactive material itself. It is almost impossible to detect because the lethal quantity is so small the eye cannot see it.

It is also easy to administer. Mixed with a tiny droplet of water it can be either inhaled or consumed by the victim, who will not detect any smell or taste and can walk away from the site of his poisoning.

It can be safe and easy to transport because its radioactivity cannot pass through skin or even thin plastic, so it can be carried around in a drop of water in a plastic container.

If the person carrying it gets some on their skin they can wash it off and suffer no harmful effects. The drawbacks are that it has a short life, which means that once created, it has to be used fairly quickly, and it is not easy to get hold of.

“Polonium is pretty sophisticated because you need such small amounts. If you have a lot of criminal energy you can think of classical ways of poisoning. But polonium is pretty exotic as a poison. Luckily, it’s not easily available, otherwise it would be simple,” he said.

Polonium occurs naturally and is even one of the ingredients that cigarette smokers take into their lungs every time they smoke — but in very tiny amounts, says Dr Leutzenkirchen.

But he says it is most unlikely the polonium used to poison Mr Litvinenko came from a natural source and analysis of any traces from his body should confirm this.

Then comes the almost impossible job of discovering which reactor produced the polonium.

“Any of the reactors I know insist on you having a licence to experiment with radioactive material. You must tell the operators what you are doing and what you want to do with it. The rules are very strict,” he said.

The radioactive material, apparently, could have come from any reactor in the world and there are at least 50 of these, including three in Germany, three in France, one in Slovenia, one in Morocco, several in Britain and numerous reactors in Russia.

Most of these produce radioactive isotopes for medical purposes, either as cancer therapy or as a diagnostic tool and they are also produced for solid-state physics research.

Russia is believed to be the biggest producer of polonium and exports 80 grams — considered a huge quantity — yearly to the US.

Polonium was identified by Marie Curie, who called it after her native Poland. Unaware of its effect, she and her husband worked with it in their home laboratory and it eventually affected their health.

It is part of the chain of decay of uranium that during its life develops from highly radioactive uranium to eventually become lead. Polonium -210 occurs close to the end of this cycle of development.

It is highly radioactive and has a half-life of 138 days, unlike uranium which has a half-life of 760 million years. This means that every 138 days, half the quantity of polonium loses its radioactivity.

But when it comes to living beings, this is little consolation given that a miniscule quantity is dangerous. For instance, 0.1 to 1 microgram is a lethal quantity. This amount is much smaller than a speck of dust and would need to be multiplied 1,000 or more times for it to be visible to the human eye.

The lethal dosage is 100 times greater than the amount used in radio therapy to destroy cancer cells, remaining lethal in the body for long enough to kill a person and destroying the body’s cells so each organ is unable to function.

“Roughly a week after a person ingests 0.1 milligram there is still a lethal dose in the body,” said Dr Leutzenkirchen.

He believes it is not easy for a person who has taken polonium to contaminate somebody else, as it does not pass through the blood-lung barrier. Its presence is best detected in a victim’s urine.

Polonium can be detected easily enough using hand-held radioactive detectors. But the traces now turning up in aeroplanes, restaurants and hotels could have leaked from the container used to carry it, he speculates.

Tracing its source means getting a good sample and trying to isolate any other elements with it to discover how it might have been produced.

“But if you only have an atom you can say very little about it. It’s like being given water that has been purified but which originally came from the Thames and the Rhine and being asked to identify which is which. It’s impossible. This is where you need good police,” he says.