The bizarre assassination of spy-turned-whistleblower Alexander Litvinenko has drawn attention to a mysterious radioactive element, polonium.
Ingested or inhaled, it is extraordinarily lethal, even in microscopic doses. It's no new-age ingredient --polonium was discovered in 1898 by Marie and Pierre Curie, who named it after their Polish homeland. What's new is that Mr. Litvinenko appears to be the first person who has ever been deliberately poisoned with the it.
Writing in The Wall Street Journal, Peter Zimmerman, a physicist at King's College London, described the choice of polonium-210, the isotope that killed Mr. Litvinenko, as the result of "perverse genius."
That's because polonium is 5,000 times as radioactive per gram as radium and, according to one science writer, a trillion times more toxic than cyanide. Prof. Zimmerman says Mr. Litvinenko must have suffered horribly because "it was as if his internal organs received a severe sunburn and peeled."
The Health Physics Society says that three millicuries of polonium is enough to kill. (A millicurie is the amount of radiation given off by one-thousandth of a gram of radium).
"Because polonium's radioactivity is so high," says Prof. Zimmerman, "one millicurie of polonium would weigh only 0.2 millionths of a gram."
United Nuclear Scientific Supplies distributes radio-isotopes over the Internet, including polonium-210. But in a recent statement posted on its website, United Nuclear said the only isotopes it sells are an "exempt quantity" amount, meaning the quantities are so small (and they are electroplated on the inside eye of a needle) that they are not considered hazardous by the U.S. Nuclear Regulatory Commission.
United Nuclear does not carry any stock, and any orders it receives are sent to the NRC-licensed reactor in Oak Ridge, Tenn.
It says that one would need about 15,000 of its polonium-210 needles, at a cost of about $1-million U.S., to have a toxic amount.
"If you really wanted to poison someone, you would of course have to come up with a way to remove the invisible amount of material from the exempt sources, which is about physically impossible, and combine them together."
Perhaps that is one reason why news reports speculate that British investigators are looking to nuclear facilities in Russia as the source of the polonium that killed Mr. Litvinenko.
Sergei Kiriyneko, head of Russia's state atomic energy agency Rosatom, told the government daily Rossiiskaya Gazeta yesterday that Russia produces about eight grams of polonium a month but that it is strictly controlled.
Polonium-210 does not stick around for very long. It has a half-life of 138 days, which means its radioactivity will be reduced by 50 per cent in that time. According to one environmental radiochemist, that suggests the dose that killed Mr. Litvinenko was produced recently.
One advantage of polonium to assassins is that, properly stored in a vial, it is undetectable.
"You could carry it around in a box, and no one would know you had any by the radiation," Yale University geophysics professor Karl Turekian told The National Interest online.
"It would get warm if you had a lot of it, but no one could detect it if you had a vial surrounded by sawdust."
However, once it is released, as in Mr. Litvinenko's body, its captured properties can give clues to investigators about where it was manufactured.