harddian.com

WHEN the former K.G.B. agent Alexander V. Litvinenko was found to have
been poisoned by radioactive polonium 210 last week, there was one
group that must have been particularly horrified: the tobacco industry.

The industry has been aware at least 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.

How much polonium is in tobacco? In 1968, the American Tobacco Company
began a secret research effort to find out. Using precision analytic
techniques, the researchers found that smokers inhale an average of
about .04 picocuries of polonium 210 per cigarette. The company also
found, no doubt to its dismay, that the filters being considered to
help trap the isotope were not terribly effective. (Disclosure: I’ve
served as a witness in litigation against the tobacco industry.)

A fraction of a trillionth of a curie (a unit of radiation named for
polonium’s discoverers, Marie and Pierre Curie) may not sound like
much, but remember that we’re talking about a powerful radionuclide
disgorging alpha particles — the most dangerous kind when it comes to
lung cancer — 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.

We should also recall that people smoke a lot of cigarettes — about
5.7 trillion worldwide every year, enough to make a continuous chain
from the earth to the sun and back, with enough left over for a few
side-trips to Mars. 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.

Is it therefore really correct to say, as Britain’s Health Protection
Agency did this week, that the risk of having been exposed to this
substance remains low? That statement might be true for whatever
particular supplies were used to poison Mr. Litvinenko, but consider
also this: London’s smokers (and those Londoners exposed to secondhand
smoke), taken as a group, probably inhale more polonium 210 on any
given day than the former spy ingested with his sushi.

No one knows how many people may be dying from the polonium part of
tobacco. There are hundreds of toxic chemicals in cigarette smoke, and
it’s hard to sort out how much one contributes compared to another —
and interactive effects can be diabolical.

In a sense, it doesn’t really matter. Taking one toxin out usually
means increasing another — one reason “lights” don’t appear to be much
safer. What few experts will dispute is the magnitude of the hazard:
the World Health Organization estimates that 10 million people will be
dying annually from cigarettes by the year 2020 — a third of these in
China. Cigarettes, which claimed about 100 million lives in the 20th
century, could claim close to a billion in the present century.

The tobacco industry of course doesn’t like to have attention drawn to
the more exotic poisons in tobacco smoke. Arsenic, cyanide and
nicotine, bad enough. But radiation? As more people learn more about
the secrets hidden in the golden leaf, it may become harder for the
industry to align itself with candy and coffee — and harder to
maintain, as we often hear in litigation, that the dangers of tobacco
have long been “common knowledge.” I suspect that even some of our
more enlightened smokers will be surprised to learn that cigarette
smoke is radioactive, and that these odd fears spilling from a
poisoned K.G.B. man may be molehills compared with our really big
cancer mountains.

Robert N. Proctor is a professor of the history of science at Stanford
University.