Is it radioactivity that makes tabacco kill? How to get non-radioactive tobacco?

November 11, 2007 3:49 AM

Is there any truth to the suggestion that, "Many scientists believe that cancer deaths among smokers are due to the radioactive content of tobacco leaves and not to nicotine and tar" (source). If so, where does one get non-radioactive tobacco?
posted by MetaMonkey to health & fitness (36 answers total)

Well, it's New Scientist, so it's good to take anything they say with a grain of salt. But they are quoting an paper in a peer-reviewed journal. Unfortunately, I don't have access to the full text so I can't look up the citations that Papastefanou relies on.

As far as avoiding radioactive tobacco, you can't. Radioactivity is everywhere. You might be able to find less radioactive tobacco. The article indicates that some of the leaves he looked at had more than 2.5 times the radioactivity of others. I doubt there is widespread information on the radioactivity of commercial cigarettes, but I could be wrong. You would probably have to measure it yourself.
posted by grouse at 3:57 AM on November 11, 2007

an paper
posted by grouse at 3:58 AM on November 11, 2007

I read a very similar, but not exactly the same claim that's in your article very recently. In the one I read, it differed because it said that the tobacco plants were radioactive, not because the radioactivity is "found naturally in the tobacco", but rather because of the fertilizers they use. They said the organic American Spirits don't use it. Otherwise, maybe you could grow your own. Or, you could not smoke.
posted by evariste at 3:58 AM on November 11, 2007

It's not radioactivity in tobacco that kills you.
posted by public at 4:02 AM on November 11, 2007

public, the claim is about the source of cancer, not tobacco-related deaths in general.

Here is an an article that suggests that lung cancer can be caused by non-tobacco-related radon daughters which attach to smoke particles.
posted by grouse at 4:20 AM on November 11, 2007

Man, I'd never heard that before. Clearly there are a few scientists looking at it, but public is spot on:

It's not radioactivity in tobacco that kills you.
Bears repeating.
posted by kisch mokusch at 4:20 AM on November 11, 2007

I should clarify; I would like to know

1. if it is plausible that it is the radioactivity that makes tobacco so dangerous.

2. if it possible to buy tobacco not grown in radioactive fertilizer.

Stating, "It's not radioactivity in tobacco that kills you" without any kind of source is not really helpful.
posted by MetaMonkey at 4:24 AM on November 11, 2007

The question is specifically about cancer. Please can answers be confined to discussion of whether radioactive fertilizer is the major cause of cancer, and if so whether this can be avoided by buying tabacco grown differently. (sorry if my question wasn't expressed very well, I'm just fairly stunned by the idea that the risk of tabacco-related cancer can be severely reduced)
posted by MetaMonkey at 4:34 AM on November 11, 2007

If tobacco is significantly radioactive, the statement is at least half true. More cancer will come from radioactivity than nicotine.

Nicotine doesn't give you cancer, it just typically makes you addicted to the stuff that does. Wikipedia is pretty informative on this.
posted by cheerleaders_to_your_funeral at 4:43 AM on November 11, 2007

There are definitely other, non-radioactive, cancer-causing chemicals in tobacco, specifically when processed into cigarettes and smoked. They may or may not be as dangerous as the radioactive chemicals, no one can say for sure yet.
posted by anaelith at 4:48 AM on November 11, 2007

Search "polycyclic aromatic hydrocarbon carcinogen" at this site, you'll get 2532 references (sorry, can't seem to link to the search). That's because polycyclic aromatic hydrocarbons with four to six rings are potent carcinogens, and are considered the major carcinogens in tobacco smoke.

Yes, it is possible that radioactive elements in tobacco could also contribute to cancer, but taking away radioactive fertilizer will not take away tobacco smoke's ability to cause cancer.

If you want to reduce the risk of cancer from tobacco, eat it (not completely risk free though).
posted by kisch mokusch at 4:48 AM on November 11, 2007 [2 favorites]

If you could significantly reduce the harm caused by smoking (especially if you can do so without affecting the addictive quality or otherwise changing the experience), I would have expected the tobacco industry to get on it and be advertising 'NEW SAFER cigarettes: 20% less death!' somehow. Given that this hasn't happened, I tend to assume it's not possible.
posted by jacalata at 5:17 AM on November 11, 2007

Even if radioactivity were the only cause of cancer, tobacco would still be naturally radioactive. I would be interested in the claim evariste refers to that fertilizer is the root cause of radioactive tobacco.
posted by grouse at 5:42 AM on November 11, 2007

I would be interested in the claim evariste refers to that fertilizer is the root cause of radioactive tobacco.

Yes, this is the part I am most curious about. On reflection, I could have phrased my question a whole lot better.
posted by MetaMonkey at 6:01 AM on November 11, 2007

In Papastefanou's 2001 paper indicates that the sorts of radioactivity discussed in the 2007 would not have come from fertilizer, but either from natural soil or the air.
posted by grouse at 6:16 AM on November 11, 2007

Why would fertilizer be radioactive?

Potassium-40.

And why would radioactive fertilizer be used used on all tobacco and on nothing else whatever?

It would be used on all sorts of things, but you don't smoke most of those things, hence they are going to afford a negligible increase in the risk of lung cancer.
posted by grouse at 6:28 AM on November 11, 2007

[a few comments removed - the OP has clarified the question, take derails to metatalk please.]
posted by jessamyn at 7:03 AM on November 11, 2007

There was a related Straight Dope article about this a couple months ago.
posted by BigFatWhale at 7:09 AM on November 11, 2007 [2 favorites]

The conclusion of that article states "The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production has been studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring radionuclides and Cesium-137 of Chernobyl origin."

It is solely concerned with testing the levels of various radionuclides, and has no information about either the relative risk of the radionuclides as compared to other substances present in tobacco, or about any radioactive substances present as a result of the fertilization process. And the "increased risk" quote is not in the article, they must have talked to him directly.
posted by louigi at 9:31 AM on November 11, 2007

Sorry, I meant the quote in your question.
posted by louigi at 9:31 AM on November 11, 2007

The tobacco plant takes up and concentrates certain radioactive compounds as part of its life cycle; one that has been pointed at is polonium-210. It's sort of like mercury in apex-predator fishes; if the fish is going to live its whole life in the ocean, it's going to take up a certain amount of mercury. The same is true of tobacco; these isotopes are naturally present in the soil. So you can't get non-radioactive tobacco any more than you can get mercury-free tuna.

This google search is a stepping off point to learn more.

My own feeling is that the levels of radioactivity we're talking about here are so miniscule compared to other environmental sources that there is no chance they could be causing any part of the excess cancers seen in tobacco smokers.
posted by ikkyu2 at 9:34 AM on November 11, 2007

louigi: as I noted above, the author previously stated that these substances would not have come from fertilizer.
posted by grouse at 9:34 AM on November 11, 2007

grouse: I don't mean to question Papastefanou's work in any way, but generalizing in things like this can be tricky. They do seem to have a good sample set for Greek tobacco, but I don't think their results apply to all tobacco cultivation everywhere. I would be very surprised if the paper ( which I haven't read - not at work ) claimed that the radioactivity in tobacco always comes from the soil, and not from fertilizer, based on their own results.

Papastefanou has another paper here discussing dose estimates: Just from reading the abstract, results seem to be in the order of natural background dose. This agrees well with Ikkyu2's comment, which is also my feeling, particularly if you factor in all the other nasty stuff known to be in tobacco smoke. I have to note though that the long term effects of low-level exposure are a subject of much debate, as they are notoriously difficult to study.

As an extra fun fact, increased Po-210 levels can be easily measured in the urine of smokers (which does not mean something particularly bad - it's just easy to measure).
posted by the number 17 at 10:24 AM on November 11, 2007

By the way, the opening paragraph of the New Scientist article is really disingenuous: Chernobyl Cs-137 uptake in plants is probably hardly measurable today in most parts of the world, it's no surprise Ra-226 / Po-210 doses are much higher.
posted by the number 17 at 10:43 AM on November 11, 2007

the number 17: I agree on being cautious about overgeneralizing. Here is what the 2001 paper says:

The results show that ²²⁶Ra and ²²⁸Ra concentrations in tobacco leaves were comparable, reflecting their origin in soil by root uptake rather than in fertilizers used for cultivation in the fields. It is known that ²²⁶Ra (²³⁸U) in soil ranges from 10 to 50 Bq kg^x2212;1 (average 25 Bq kg^x2212;1) and ²²⁸Ra (²³²Th) in soil ranges from 7 to 50 Bq kg^x2212;1 (average 25 Bq kg^x2212;1) (UNSCEAR, 1982). Papastefanou (2000) reported that ²³⁸U concentrations in phosphate fertilizers ranged from 312 to 936 Bq kg^x2212;1 (average 638 Bq kg^x2212;1), Thorium-232 concentrations in phosphate fertilizers ranged from 3 to 81 Bq kg^x2212;1 (average 26 Bq kg^x2212;1).

posted by grouse at 10:54 AM on November 11, 2007

Goddamn you, live preview. "x2212;" means "–"
posted by grouse at 10:55 AM on November 11, 2007

It only makes sense: this doesn't imply it is always the case, just for the samples they analysed.

The Straight Dope article quoted above says that natural radioactivity mostly comes from soil uptake, but the effect of fertilizer can be measured.

The biokinetics of natural radioactivity in tobacco would make an excellent PhD subject - it may well have been done already, but I doubt we can settle it in this AskMe.

If anyone is up for doing a review paper, you know how to reach me
posted by the number 17 at 11:16 AM on November 11, 2007

It has been my understanding that the primary carcinogens in tobacco were nitrosamines.
posted by 517 at 11:50 AM on November 11, 2007

Would the earliest studies showing a link between tobacco use and cancer pre-date the use of radioactive fertilizer?

(This is not to say that radioactive fertilizers don't increase the risk of cancer, of course.)
posted by aeschenkarnos at 1:20 PM on November 11, 2007

You say "radioactive fertilizer" as if there were any other sort.
posted by grouse at 1:40 PM on November 11, 2007 [2 favorites]

Searching on Polonium 210, cadmium, and radioactiv* in the tobacco document archive will take up months of your time and educate you on the subject.

kisch mokusch got the real cause of tobacco-related lung cancer in one (polycyclic hydrocarbon act upon the p53 gene and start cancer). Nicotine, meanwhile, is a poison to the cardiovascular system (this kills at least as many smokers as respiratory disease).

Radioactivity adds in to the process of illness, I'm sure, but the tobacco industry hasn't done as much research on this as they have on the other elements of why cigarettes kill. (They are still years ahead on medical research in these areas, natch.)
posted by Riverine at 4:05 PM on November 11, 2007 [1 favorite]

Many nuts contain radioactivity, but I'm not aware of any association between nut eating and gastric cancer. Surely the dose is fairly small compared to ambient exposure?
posted by Mr. Gunn at 4:15 PM on November 11, 2007

Many nuts contain radioactivity, but I'm not aware of any association between nut eating and gastric cancer. Surely the dose is fairly small compared to ambient exposure?

It seems so. Using a low-energy gamma scintillator with an energy window on your meter set to eliminate all events outside the signature peak of K40, it is possible to read whether someone is a vegetarian or an omnivore, because vegetarians (like tobacco apparently) are more radioactive on account of their higher K40 uptake.
The amount of background radiation that this instrument setup is ignoring in order to pick out the difference in K40 levels is substantial, though I couldn't put a figure on it offhand. I don't know if a smoker's lungs can be sensed in a similar way to vegetarianism, but it would make an interesting amateur experiment.

And of course it goes without saying that non-smoking vegetarians do not experience elevated levels of cancer comparable to those of smokers. (Indeed, just paying that little bit more attention to diet than Joe "greaseburgers-for-breakfast" Average can pay off significantly in the cancer stakes :-)
posted by -harlequin- at 11:09 PM on November 11, 2007

Pottasium-40 exposure is not really the issue being debated with regard to tobacco. If this was the case, bananas would be banned before smoking. Furthermore, the organism has mechanisms to regulate potassium content - your body already contains about 7 kBq of K-40, I doubt smoking can change this figure to a measurable extent.

Uranium and thorium series a-emitters are what people are worried about, Po-210 being one example already mentioned.
One of the reasons for this is that a-emitters carry significantly more internal exposure risk: Gammas, like the ones emitted by K-40 are less damaging to the body, as they are not absorbed as efficiently as alpha particles. Furthermore, residence times for these radionuclides will probably be much longer than for K-40, particularly when they are deposited in the form of smoke particles.

Now we have another PhD subject: Biokinetics of radionuclides inhaled in tobacco smoke. Remember to do a paper on in-vivo measurement of activity in smoker lungs, but don't hold your breath for the results. Also, I don't know what energies you are familiar with, but K-40 photons at 1461 keV aren't considered low energy for measurement purposes.
posted by the number 17 at 11:38 PM on November 11, 2007

It's not a completely ridiculous hypothesis, as polonium-210 is a daughter product of radon which is the second highest cause of lung cancer after smoking in the US at least. It's a teeny tiny dose, but the problem comes that it's alpha, and it's inside your body, which means that it can cause signficant local damage.

That being said, I have no idea if the cancer in smokers manifests the same way medically. And the levels they're talking here are naturally occuring, so unless you alpha count every batch and only pick the lowest.... Sounds like organic tobacco may be lower, but I wouldn't count on that to save you, given the other nasties in cigarette smoke.

Or what the Straight Dope article said.

And the Chernobyl stuff is an odd comparison to report. It's really more of an "also-measured".
posted by kjs4 at 11:36 PM on November 12, 2007

Many thanks for the help and useful answers all, it seemed worth a question given the stakes! My apologies again for doing a bad job of posing the question.
posted by MetaMonkey at 1:24 AM on November 13, 2007