Now that the former K.G.B. agent Alexander V. Litvinenko was found to have been poisoned by radioactive polonium 210 last week, there are some old facts that are coming to new attention.
The tobacco industry has been aware, since the 1960s, that cigarettes contain significant levels of polonium. Exactly how it gets into tobacco is not entirely understood, but uranium “daughter products” naturally present in soils seem to be selectively absorbed by the tobacco plant, where they decay into radioactive polonium. High-phosphate fertilizers may worsen the problem, since uranium tends to associate with phosphates. In 1975, Philip Morris scientists wondered whether the secret to tobacco growers’ longevity in the Caucasus might be that farmers there avoided phosphate fertilizers.
In 1968, the American Tobacco Company began a secret research effort to find out about how much polonium was in cigarettes. The researchers found that smokers inhale an average of about .04 picocuries of polonium 210 per cigarette. The company also filters did not trap the polonim isotopes.
A fraction of a trillionth of a curie doesn't sound like much, however, these are powerful radionuclide disgorging alpha particles that are considered the most dangerous kind when it comes to lung cancer. As it turns out, these are at a much higher rate even than the plutonium used in the bomb dropped on Nagasaki. Polonium 210 has a half life of about 138 days, making it thousands of times more radioactive than the nuclear fuels used in early atomic bombs.
If .04 picocuries of polonium are inhaled with every cigarette, about a quarter of a curie of one of the world’s most radioactive poisons is inhaled along with the tar, nicotine and cyanide of all the world’s cigarettes smoked each year. Pack-and-a-half smokers are dosed to the tune of about 300 chest X-rays.
Just thought you'd like to know.