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Third-hand smoke contains carcinogens too, study says

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third-hand smoke carcinogens tobacco nitrous acitAnyone walking into a smoker’s abode can tell you that the traces of tobacco use don’t vanish when a cigarette or cigar is extinguished. But just what happens to this "third-hand" smoke once the air has cleared—and can it still be harmful?

A team of researchers at the Lawrence Berkeley National Laboratory found that remnants of a smoke don’t just inertly settle onto surfaces, they can react with a common gas (nitrous acid, which is emitted from gas appliances and vehicles, among other sources) to create carcinogenic compounds known as tobacco-specific nitrosamines (TSNAs). The group reported the findings in a study published online February 8 in the Proceedings of the National Academy of Sciences.

These "TSNAs are among the most broadly acting and potent carcinogens present in unburned tobacco and tobacco smoke," Hugo Destaillats, a chemist at the lab’s Indoor Environment Department and coauthor of the paper, said in a prepared statement.

Second-hand smoke itself contains TSNAs, but the presence of nitrous acid in an environment can increase their numbers in the hours after smoking has ceased. "Whereas the sidestream smoke of one cigarette contains at least 100 nanograms equivalent total of TSNAs, our results indicate that several hundred nanograms per square meter of nitrosamines may be formed on indoor surfaces in the presence of nitrous acid," Mohamad Sleiman, lead author of the study and also of the Berkeley Lab, said in a prepared statement. And given that nicotine can linger on surfaces for weeks and months—even on hard ones, such as walls or dashboards—the finding shows that this form of exposure might be even more persistent than first- or second-hand smoke.

"Our findings indicate that third-hand smoke represents an unappreciated health hazard," Sleiman said. And the potential harm comes not just from breathing these molecules in, but also from direct skin contact and incidental ingestion, the authors noted, calling into question some purported benefits of smoking outside. "Smoking outside is better than smoking indoors, but nicotine residues will stick to a smoker’s skin and clothing," Lara Gundel, a researcher at the lab and coauthor of the study, said in a prepared statement. "These residues follow a smoker back inside and get spread everywhere."

Third-hand smoke is a relatively new concept, but like the better-known bugaboo, second-hand smoke, the most vulnerable population is likely children. "Dermal uptake of the nicotine through a child’s skin is likely to occur when the smoker returns, and if nitrous acid is in the air, which it usually is, then TSNAs will be formed," Gundel said. Young children are also more likely to consume more dust—and thereby any present TSNAs—than adults, they report.

To stamp out third-hand smoke, the authors recommend public places be entirely smoke-free and individuals avoid smoking indoors and in their cars. Also, in enclosed spaces that have seen plenty of puffs over the years, they suggest replacing furniture, carpet and even wallboard to cut down on the amount of TSNA exposure.

Image courtesy of Wikimedia Commons/Opa

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  1. 1. bobsmith1234 3:52 pm 02/8/2010

    What about fourth hand smoke?

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  2. 2. Dtalon3 4:23 pm 02/8/2010

    sorry this is ridiculous. Maybe we should look into the effects of second hand alcohol ingestion. DON’T KISS YOUR KIDS AT NIGHT IF YOU WERE DRINKING…OTHERWISE YOU COULD GIVE THEM ALCOHOL POISONING. This feels like a push to try and get rid of cigarettes altogether.

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  3. 3. candide 4:41 pm 02/8/2010

    Please do not call them ‘smokers’ – they are nicotine addicts.

    We do not call heroin addicts jabbers or needle users, they are addicts, why are nicotine addicts treated so differently?

    All these anti-smoking regulations and laws started when smokers could not even be considerate enough to NOT smoke on elevators, remember that?

    It progressed from there, addicts lack of consideration.

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  4. 4. cshine 4:47 pm 02/8/2010

    Good thing that Dtalon3 is not making a knee-jerk comment based on emotion rather than scientific evidence….

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  5. 5. Daneel Olivaw 4:57 pm 02/8/2010

    This appears to be a basic science paper. There needs to be some followup epidemiological studies to see if the quantity of TSNA are enough to cause damage.

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  6. 6. hellblade 5:30 pm 02/8/2010

    it was always my opinion that an overwhelming majority of poisonous chemicals in cigarette smoke comes not from tobacco itself but rather from hundreds of synthetic aditives. wikipedia lists 599 of them. some are obviously aromatic, but other seem downright poisonous, especially when burned.

    what possible reason is there to put 599 different chemicals in a cigarette?

    also, is there a study that compares industrial cigarettes with their home-made counterparts? i think it would be quite interesting to see the results, and by extension, it is obvious that such studies would not bode well with big tobacco companies.

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  7. 7. Bops 7:03 pm 02/8/2010

    I agree with candide.

    People who smoke are addicted to nicotine.
    I read that smoking kills 91% from cancer, heart, lung and fires.


    All form of burning are carcinogenic to a degree.
    So, why do it? Find another bad habit that won’t kill you.

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  8. 8. scientific earthling 7:58 pm 02/8/2010

    The American Indians were the first people to smoke, has any research been done to determine the impact it had on them?

    Perhaps the impact of smoking is exacerbated by an industrial society? Nitrous oxides other than those from natural origins would have been few in the old Indian habitats, furnishings would not have had surfaces that allow nitrosamines to condense on them and remain active for long periods, further they may not have smoked as much as industrial age humans do. The answer is there to be had for anyone looking.

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  9. 9. sds 8:16 pm 02/8/2010

    It is specious to bring up the American Indians in a conversation about nicotine addiction. They didn’t have the one to two pack a day habit that addicts have today.

    If there’s anything good to come of smoking cigarettes, I haven’t heard or read about it yet.

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  10. 10. hellblade 9:24 pm 02/8/2010

    bops, i understand that any smoke, by default, is unhealthy to a certain degree. but i bet that home-grown tobacco is many many times less dangerous than the smoke from industrial cigarettes. as i sad, 599 additives… that’s just crazy! there really should be a study comparing unmodified tobacco with industrial tobacco. just to show people the difference. i’m certain it would be huge.

    also, i don’t smoke. if i did, i would buy home-grown tobacco and roll my own cigarettes.

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  11. 11. tonto1 11:32 pm 02/8/2010

    The U.S. could not make smoking illegal in public because of religion, or because it was a risk to a user, so they came up with second hand smoking laws (using children as there excuse) making smoking in public places illegal, but the law proved it was a religious law that could be used to make it easy to discriminate against non smokers and to discriminate against all tobacco users, not just smokers. The research was based on numbers of smokers and there was no numbers of smokers who were exposed to other things also, like agent orange or mouth wash that causes cancer or the age factor of 45 when the immune system gets week. Now if risk is going to be a factor then we also must make war illegal, sky diving illegal, bungy jumping illegal and put a brand the forehead of people with HIV. We would never have conquered the old West without risk the pioneers took to move West. We have become a sissy nation made up of people that can’t tolerate anything and soon farting will be illegal.

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  12. 12. curio93 6:09 am 02/9/2010

    what about the billions of cars driving around spewing their noxious filth into the air? i’m sure these have 3rd, 4th and 5h levels of consequence

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  13. 13. imsureyoudisagree 10:32 am 02/9/2010

    this is ridiculous. its just another biased study attempting to affect public policy. there are far more dangerous carcinogens present in larger quantities in indoor environments that apparently are not worth studying. notice that they don’t propose reducing the amount of nitrous acid in indoor environments, instead they find a way to blame nicotine. The amount of carcinogens in second and now ‘third’ hand smoke are unlikely to cause illness, indoors or out. its hard to find the facts because the anti-smoking lobby has won the fight by being the squeakiest wheel, but they are out there if you look. this argument has never been about public health. it was brought about by a few loud-mouth whiners that don’t like the smell of cigarette smoke. if you don’t like smoke make your home non-smoking and stay there and stop trying to create public policy that infringes on others peoples’ rights based on half-baked science.

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  14. 14. sparcboy 12:50 pm 02/9/2010

    sds….one good thing that comes from nicotine addiction/tobacco smoking is the tobacco companies and their stockholders get to line their pockets while the addicts that buy their products get sick and die.

    That’s good…good and evil!!!

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  15. 15. coffeebreak 2:20 pm 02/9/2010

    All I can say is there isn’t any big money to be made in a healthy American…

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  16. 16. samuelwu 2:40 pm 02/9/2010

    You say that like it’s a bad thing?

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  17. 17. tonto1 2:56 pm 02/9/2010

    Most non smokers complaining about smokers are also complaining about having no rights anymore and wonder why.

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  18. 18. coffeebreak 3:15 pm 02/9/2010

    No…I’m saying that like it’s an evil/sad truth. Companies, portions of government, etc. go where the "big money" is, regardless of who it hurts or who they have to step on in order to attain wealth of sorts.

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  19. 19. jack.123 6:09 pm 02/9/2010

    Where do theses people get all this money for useless research,and where can I get some?

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  20. 20. dj95401 1:15 am 02/10/2010

    I agree with Dtalon3, second hand alcohol is a hell a lot more deadly than second, third or fourth hand smoke, it will kill the innocent quicker than any commercial or home grown cigarette. YA, today it’s politically incorrect to smoke and it is politically correct to drink a glass or two or three or bottle(s) of Wine a night, that’s OK. And I guess that if your a politically correct Wine drinker you could possibly die from a healthy case of cirrhosis of the liver, if you don’t kill yourself and or somebody else sooner in the process. Yes they both will kill you, it’s just one is more politically correct.

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  21. 21. sparcboy 1:44 pm 02/10/2010

    dj95401 – "it’s just one is more politically correct"…
    Yes, and consider that in light of the Toyota recall.

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  22. 22. Joetheplumber 12:00 am 02/11/2010

    I believe I have a right to decide to make that choice for myself. The government shouldn’t force good health on its citizens at the cost of personal freedom.

    There are a lot of things that can kill you in this world. I know several people I consider addicted to caffeine. And some people who are addicted to junk food. What’s next, limits on how many calories you can consume in a day? Limits on how many lattes you can drink in a day? I have an idea: let’s start calling obese people "Food Addicts" and have government employees follow them around to monitor what they eat.

    Either that, or we can agree that people should have the right to make their own decisions regarding their body. Prohibition of smoking is going to be as pointless as the drug war or prohibition of alcohol or abstinence-only sex education.

    And not everyone who smokes is addicted. I smoke once a week, if that. Just because something is addictive doesn’t mean everyone is addicted, and it’s not like anyone who ends up addicted to nicotine wasn’t aware of the risks when they started smoking.

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  23. 23. Michael J. McFadden 1:29 am 02/11/2010

    If you read the study itself you’ll find they "assumed" a "high but reasonable" level of SIXTY for their HONO value. But if you follow the references they give you’ll find that the average HONO level in houses is FOUR.

    Do you understand what that means? It means they got their "scary numbers" by exaggerating normal conditions by a whopping 1,500%.

    Don’t believe the nonsense you read in antismoking press-release-based news stories. Do some research yourself if you want an informed opinion and you might be surprised at what you find. Check out my AfterComments at:

    to see the games they played a year ago with the last ThirdHand Smoke story. They’re playing a social engineering game, abusing our love for our children in a cold and calculated way to push smokers step-by-step to quit whether they want to or not. Visit to see more of the lies this sort of nonsense is based on.

    Michael J. McFadden,
    Author of "Dissecting Antismokers’ Brains"

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  24. 24. Think it throufg 4:13 am 02/11/2010

    The problem with this article is not the showing of the formation of TSNAs but their levels that can cause a toxic environment weren’t measured. Therefore, the article presents alot of scare tactics but doesn’t give the most imortant information.

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  25. 25. Think it throufg 4:18 am 02/11/2010

    The problem with this article is not that they identify the existence of TSNAs but it doesn’t identify any levels of toxicity. Therefore, while these molecules can be toxic at what levels are they a danger?

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  26. 26. BJ Bonobo 4:01 pm 02/13/2010

    Tobacco is an easy grow. The curing can be a bit more of a problem but you can’t get away from the addictive power of nicotine . It is a toxic and cancer causing substance and the minute but jagged rush a one or two cigarette per day user experiences is hardly worth the time.

    Try organically grown coffee or coca leaf tea powder . The latter is a completely legal substance in the U.S.A. and can be purchased through . ( I mention that only because some may doubt it’s legality ).

    Cigarettes are deadly and should never be used in the presence of children or non smokers.

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  27. 27. BJ Bonobo 4:23 pm 02/13/2010

    I will not allow a smoker in my home. Their clothing stinks and if I can smell that stuff from a distance of six to ten feet I got to be inhaling it .

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  28. 28. Jessica Y 11:56 am 02/15/2010

    wow. third hand smoke.
    and by telling smokers not to smoke inside or outside, isn’t the article simply telling smokers not to smoke at all? it all comes down to the same conclusion.

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  29. 29. Think it throufg 6:06 am 06/23/2010

    An interesting side note- here in Italy typically doctors, that I have spoken to, do not say for people to absolutely stop smoking but to limit the intake to no more than about 8 cigarettes a day. I never got into a discussion about the rationale of this advice but it seems to be a common rule of thumb here and, of course, Italian doctors are well aware of the research on smoking.

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  30. 30. _w_ 3:38 am 09/5/2010

    Everyone who has had to visit some smokers home knows already without any more scientifical research that the smoke stays. I once rented an apartment without seeing it beforehand where the former tenant had apparently smoked inside, had to leave as could not sleep there, was coughing all the time.
    Although more research would be good as possibly then eventually there would be smoke-free housing available.

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