THE UK Health Protection Agency (HPA) is assisting the London Metropolitan Police in investigating the death of one Alexander Litvinenko, an ex-Russian spy who was poisoned with polonium-210 in a bizarre incident.

Polonium-210 (Po-210) is radioactive and occurs in nature in trace quantities. It has a half-life of nearly 138 days. It emits alpha particles and very low intensity gamma rays. Since there are sensitive instruments to detect very tiny traces of radioactivity, HPA could trace the movement of the victim and spread of contamination at several places.
Such low levels of contamination do not pose any significant risk. Large quantities of Po-210 may be prepared by irradiating bismuth-209 in a nuclear reactor.
How Litvinenko got poisoned with such a large quantity of Po-210 continues to be a mystery. He freely moved in the city and frequented many places till November 17, when he got admitted to London's University College Hospital.
He suffered loss of hair, dehydration, and vomiting. He had very low white blood cell count. These symptoms indicated severe radioactive poisoning.
On 23rd of November, just before dying of heart failure, the 43-year-old Litvinenko claimed that someone poisoned him in a London restaurant, which he visited on November 1, this year.
"To poison someone, polonium would most likely have been chemically combined in some type of dissolvable salt, for example polonium nitrate," New Scientist quoted experts in the field. "In this form, the material could easily have been added to his food and ingested", the journal clarified.
Soluble polonium-210 gets dispersed in soft tissue. Kidney and bone marrow will receive high doses.

Roger Cox, director of the U.K.'s Centre for Radiation, Chemical and Environmental Hazards told New Scientist that the fatal dose would have to be above five grays (gray is a measure of the amount of radiation absorbed by the body tissue). "The quantity of Po-210 involved in the present case may be a few millicuries or a few tenths of a microgram."


Cancer threat
An alpha particle from Po-210 has a range of about 35 microns (A micron is 0.0001centimetre) in tissue. Three or four cells will stop it. Radiation, interacting with cells may kill a few of them. Some of the cells may survive. The surviving cells have the potential to become cancerous as they may lose their precisely set growth control mechanisms.
The UK HPA found small quantities of Po-210 in a few areas at the Itsu sushi restaurant at 167 Piccadilly, London, and at Mr Litvinenko's home in Muswell Hill.

Traces located
They located traces of radioactivity at two more London locations, one of them at the offices of exiled Russian oil tycoon Boris Berezovsky, the United Press International (UPI) reported on November 28th... They found Po-210 at the offices of the private Erinys security firm, which guards oil installations. Police tried to trace Litvinenko's movements, who he met and where.
HPA asked anyone who was in the Itsu restaurant or who was in the Pine Bar or in the restaurant of the Millennium Hotel on 1st November to contact NHS (National Health Services) on a specified number for further advice. HPA found contamination in three British Airways (BA) planes flying between London and Moscow. After an overall assessment, the agency declared that the passengers who travelled on any of these planes over the last month were not at risk.
Two British Airways (BA) planes flying between London and Moscow and other European routes tested positive. "... .the risk of having exposed to this substance remains low. It can only represent a radiation hazard, if it is taken into the body — by breathing it in, by taking it into the mouth, or if it gets into a wound," the Agency reassured the public.

Precautionary measure
Since 25th November, until midnight of 28th November, HPA received 1,325 phone calls. The Agency followed up 68 people who it decided to investigate further. In addition, the Agency referred 21 persons as a precautionary measure to a specialist clinic, set up by it for possible radiological exposure evaluation.
Besides these, HPA asked 52 out of 162 healthcare staff and 105 staff or visitors to the various locations under police investigation to provide urine samples. From November 1, the body fluids (sweat, saliva, urine etc) of the victim contained polonium-210. Anyone who came into physical contact with the victim may have received traces of polonium.
It will not pose any significant risk so long as it is outside the body. Those present while carrying out autopsy on the body of the victim at the Royal London Hospital wore special protective clothing, to prevent contamination of their body with polonium.
The denial
The origin of the substance, which claimed its victim, remains unknown. According to Associated Press, Sergei Kiriyenko, director of the Russian nuclear agency, Rosatom, denied that the polonium, could have been stolen from a nuclear facility in Russia.
Kiriyenko revealed that Russia exports 8 grams of polonium-210 monthly, all of it to the United States. That is a whopping amount; what do they do with it? He said there had been no exports to Britain in five years. The HPA reports are reassuring. The incident did not pose significant risks to anyone, other than the victim.
K.S. PARTHASARATHY
Former Secretary, AERB (ksparth@yahoo.co.uk)
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