Robert N. Proctor is a professor of the history of science at Stanford University.
1 Dec 2006
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 Alphaparticles — 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.
Pneumologia. 2008 Oct-Dec;57(4):249-54.
[Polonium: the radioactive killer from tobacco smoke].
[Article in Romanian]
AUSL di Bologna, Italia. firstname.lastname@example.org
Among all carcinogenic substances contained in tobacco smoke, Polonium 210 (Po-210), with a half-life of 138 days, is one of the most dangerous, by exerting a devastating, chronic, slow and progressive carcinogenesis activity. The main source of Po-210 in tobacco is represented by fertilizers (polyphosphates) containing radium-226 (Ra-222) which decades to plumb 210 (Pb-210). Through the thricomes Pb-210 is concentrated in the tobacco leaves, where it turns to Po-210, which at the cigarette combustion temperature (800-900 degrees C) reaches the gaseous state and it is absorbed by the micro particles released into tobacco smoke. Thus, smoke becomes radioactive in both its gaseous and corpuscular components and reaches the airways, where, particularly at the branches level and together with other substances, it exerts its carcinogenic activity, especially in those subjects with impaired respiratory mucosal clearance. The carcinogenic risk/one year lifetime of a smoker of 20 cigarettes per day is equivalent to that of undertaking 300 chest x-rays. It is calculated that Po-210 may be independently responsible of 4 lung cancers every 10,000 smokers. During cigarette’s combustion, tobacco smoke is also released in the air, contributing to serious health risks for those exposed to passive smoke.
Am J Public Health. 2008 Sep;98(9):1643-50. Epub 2008 Jul 16.
Waking a sleeping giant: the tobacco industry’s response to the polonium-210 issue.
Nicotine Research Program, Mayo Clinic, Rochester, MN 55905, USA.
The major tobacco manufacturers discovered that polonium was part of tobacco and tobacco smoke more than 40 years ago and attempted, but failed, to remove this radioactive substance from their products. Internal tobacco industry documents reveal that the companies suppressed publication of their own internal research to avoid heightening the public’s awareness of radioactivity in cigarettes. Tobacco companies continue to minimize their knowledge about polonium-210 in cigarettes in smoking and health litigation. Cigarette packs should carry a radiation-exposure warning label.
Radiat Prot Dosimetry. 2007;123(1):68-73. Epub 2006 Mar 31.
Radiation dose from cigarette tobacco.
Aristotle University of Thessaloniki, Atomic and Nuclear Physics Laboratory, Thessaloniki 54124, Greece.email@example.com
The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring primordial radionuclides, such as (226)Ra and (210)Pb of the uranium series and (228)Ra of the thorium series and or man-made radionuclides, such as (137)Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the annual effective dose due to inhalation for adults (smokers) for (226)Ra varied from 42.5 to 178.6 microSv y(-1) (average 79.7 microSv y(-1)), while for (228)Ra from 19.3 to 116.0 microSv y(-1) (average 67.1 microSv y(-1)) and for (210)Pb from 47.0 to 134.9 microSv y(-1) (average 104.7 microSv y(-1)), that is the same order of magnitude for each radionuclide. The sum of the effective doses of the three natural radionuclides varied from 151.9 to 401.3 microSv y(-1) (average 251.5 microSv y(-1)). The annual effective dose from (137)Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv y(-1) (average 199.3 nSv y(-1)).
Yearly dose examples
- Living near a nuclear power station: 0.0001–0.01 mSv/year  
- Living near a coal power station: 0.0003 mSv/year 
- Cosmic radiation (from sky) at sea level: 0.24 mSv/year 
- Terrestrial radiation (from ground): 0.28 mSv/year 
- Natural radiation in the human body: 0.40 mSv/year 
- Radiation produced by the granite of the United States Capitol building: 0.85 mSv/year 
- Average individual background radiation dose: 2 mSv/year; 1.5 mSv/year for Australians, 3.0 mSv/year for Americans   
- New York-Tokyo flights for airline crew: 9 mSv/year 
- Atmospheric sources (mostly radon): 2 mSv/year  
- Total average radiation dose for Americans: 6.2 mSv/year 
- Smoking 1.5 packs/day: 13-60 mSv/year  
- Current average limit for nuclear workers: 20 mSv/year 
- Background radiation in parts of Iran, India and Europe: 50 mSv/year 
- Lowest clearly carcinogenic level: 100 mSv/year 
- Elevated limit for workers during Fukushima emergency: 250 mSv/year 
This page provides a brief overview of radiation in tobacco and its effect on smokers.
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Every year 440,000 people die in the US from tobacco use and smoke-related diseases, which is approximately 20% of all deaths in the United States. Cigarettes kill more Americans than alcohol, car accidents, suicide, AIDS, homicide, and illegal drugs combined.
While not an obvious source of radiation exposure, cigarette smokers inhale radioactive material that, over time, contribute large radiation dose to the lungs. Worse, smokers are not the only ones affected by the radiation in cigarettes. Second-hand can be just as harmful to nearby non-smokers.
Naturally-occurring radioactive minerals accumulate on the sticky surfaces of tobacco leaves as the plant grows, and these minerals remain on the leaves throughout the manufacturing process. Additionally, the use of the phosphate fertilizer Apatite – which contains radium, lead-210, and polonium-210 – also increases the amount of radiation in tobacco plants.
The radium that accumulates on the tobacco leaves predominantly emits alpha and gamma radiation. The lead-210 and polonium-210 particles lodge in the smoker’s lungs, where they accumulate for decades (lead-210 has ahalf-life of 22.3 years). The tar from tobacco builds up on the bronchioles and traps even more of these particles. Over time, these particles can damage the lungs and lead to lung cancer.
Hak Kan Lai