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December 01, 2006

Polonium 210 and Cigarettes

Robbie over at The Times points to a wonderful attempt to climb upon the bandwagon of the Alexander Litvinenko polonium 210 poisoning. The full piece is here in the New York Times.

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.

That last line has me slightly scratching my head. I don't deal with radioactive metals (rather the rare earths more generally) so I'm not about to enter the swamp of trying to convert 438 picocuries (30 cigarettes by 365 days by 0.4 picocurie per fag) into rem or sieverts to try and compare directly with chest x-rays but are we absolutely certain that he's got his numbers right there? the same as 300 chest x-rays a year?

Or, if we look at typical exposures, a chest x-ray is 0.00002 Sievert. Multiply that by 300 and we get 0.006 Sievert don't we? That's three times the regular amount we simply get from background radiation. Or 1/666 of the 50% fatal dose.

Or for the truly interested, less than the 0.008 sieverts received as background radiation by those who live in Cornwall.

So, yes, there is polonium 210 in your cigarettes. And no doubt it is dangerous (for some value of danger) for it to be there. But what we want to know is how dangerous? The answer to which would appear to be:

Smoking: Less Dangerous Than Living in Cornwall.

Update: Russell Seitz makes the same point. Alas and alack, as he so often does, more scientifically than I do.

December 1, 2006 in Health Nazis | Permalink


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Tracked on Dec 5, 2006 3:06:17 AM


First point. The slogan should be: The polonium in smoking cigarettes is less dangerous that living in cornwall

Second point. One Sievert is a millicurie of intensity hour. I think that means that if you smoke solidly for an hour and consume 4picocuries that works out at 4 nanosieverts. It doesn't really matter because a turning a picocurie to a millicurie means you need to multiply by 1,000,000,000 which is enormous

Posted by: Francis | Dec 1, 2006 6:40:37 PM

1/666 - beware the reciprocal of the beast!

Posted by: Andrew Zalotocky | Dec 1, 2006 7:02:19 PM

Interesting fraction: 1/666

Posted by: james higham | Dec 1, 2006 7:36:52 PM

A curie is 3.7 × 10^10 disintegrations per second (Bq). So one picocurie is 3.7 × 10^-2 Bq, or about one disintegration every 27 seconds. 0.04 pCu is one disintegration every eleven minutes or so. This is a level of radioactivity low enough to be difficult to measure.

A Sievert is the SI unit of dose equivalent, in other words the absorbed energy (measured in J/kg or Grays), multiplied by a 'quality factor' Q to account for the differing effects of ionising radiation. Polonium 210 emits a 5.4 MeV alpha particle, and alphas have a Q of 20. Smokers will ramp up their body burden to some steady state, at which point the Po210 (with a 138 day halflife) will be decaying and being excreted as fast as it is replenished. A n a day smoker will be taking on board 0.04n pCu per day. How many moles of Po210 is that? A 138 day halflife yields a decay constant of ln(2)/t_1/2 = 5.8 10^-8 s^-1. In other words, about 1 in 17 million Po210 atoms will decay per second. So 0.04 pCu of Po210 corresponds to about 25400 atoms of Po210 per cigarette. Around half a million atoms per day taken on board by a 20-a-day smoker. What is the steady state whole-body burden? To be steady state, the same number of atoms of Po210 must be lost per day as are being taken on. Worst case: all the loss is via Po210 decays in the smoker's body and none via excretion. Therefore each day the energy absorbed by the smoker's body is 510000 × 5.4 MeV × 1.6 10^-13 J/MeV = 4.4 × 10^-7 J/day. Multiply by our quality factor of 20 to yield 8.8 × 10^6 J/day. Assume a 100 kg guy, then the equivalent dosage per day is 8.8 × 10^-8 J/(kg day). Per year, 365 times this = 32 microsievert per year, or a 75th of the 2.4 millisievert p.a. typical of background radiation.

I would posit that this is not a significant radiological hazard.

Posted by: David Gillies | Dec 1, 2006 7:53:27 PM

A lightly amusing take-down of the NYT, with an enlightening table, here -

Posted by: view from the solent | Dec 1, 2006 7:53:47 PM

But, chaps, the tar protects you anyway. A layer of tar will absorb alpha particles just as well as the proverbial sheet of newspaper. So if the pollonium forms part of the smoke particles and tar condenses on the surface, later coming between the alpha-emitter and the cells of the lung, bingo, no radiation risk.

Posted by: dearieme | Dec 1, 2006 8:01:39 PM

Yes, tits to you all. I love a Marlboro light and I won't be told otherwise by any of you, you fuckers.

Sorry to use your comments to say it Tim, but fuck, fuck, fuck all these arseholes who bleat about my smoking - what the fuck is it to you?

Fuck right off, arseholes.

Sorry again, but they refuse to listen.

Posted by: Flying Rodent | Dec 2, 2006 2:22:09 AM

Hi Tim,
You are right, one should not underestimate the dose of chest x-rays. However, there is a polonium problem associated with smoking, but this is not in the cigarettes themselves. The problem is caused by the radon daughters in the air (see my link for decay chain). The ions tend to attach themselves to smoke and dust particles. The noble gas radon is inhaled and exhaled - not a real health problem. But the decay products on smoke particles tend to stay behind in your lungs. That is why levels of polonium are higher in smokers. (My understanding - I am not a medical person.)

Posted by: Pieter Kuiper | Dec 3, 2006 11:08:47 PM

Power to the people is, is not a good idea

Posted by: frame | Oct 16, 2007 5:02:11 PM

what aobut the other types of radioactive particles? or is there only polonium 210?

Posted by: Matt | Jun 18, 2008 5:24:42 PM