Thursday 11 February 2010

The thirdhand smoke scam

Now that the thirdhand smoke story has been reported around the globe, it's time to look at the study which led to headlines such as:

Third-hand smoke causes cancer, study shows risks to babies and toddlers

This is not your average piece of epidemiological number-crunching. It involved some real lab work which, when written down, is largely unintelligible to the layman*. Journalists rarely bother to read scientific studies at the best of times, but what chance do they have with paragraphs like this?

Laboratory experiments using cellulose as a model indoor material yielded a > 10-fold increase of surface-bound TSNAs when sorbed secondhand smoke was exposed to 60 ppbv HONO for 3 hours. In both cases we identified 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal, a TSNA absent in freshly emitted tobacco smoke, as the major product. The potent carcinogens 4-(methylnitrosamino)-1-(3-pyridinyl)-1-butanone and N-nitroso nornicotine were also detected. Time-course measurements revealed fast TSNA formation, with up to 0.4% conversion of nicotine. 

And that's from the abstract - the bit that summarises the study for the casual reader. So what does it actually say?

To put it in something close to simple terms, the experiment involved putting nitrous acid (HONO) in contact with nicotine. The nicotine had been absorbed into surfaces (hence 'thirdhand smoke'). In the real-life experiment, this surface was the glove compartment of a truck driven by a heavy smoker (presumably the cabin of a truck was chosen because it is the smallest space a smoker might work in). In the other experiments, they used cellulose substrates. 

The aim was to see if the reaction created tobacco-specific nitrosamines (TSNAs), specifically NNK, NNA and NNN, some of which are believed to be carcinogenic.

The scientists found no trace of NNN in any experiment. In the glove compartment, they found levels of NNK that were barely above the detectable level (less than 1 ngcm-2). Even in extreme experimental situations, in which cellulose substrates were exposed to pure nicotine vapour, NNK levels failed to reach 5 ngcm-2.

They found somewhat larger measurements of NNA (20 ngcm-2 in extreme experimental conditions) but levels were much lower in the real-life conditions of the truck (1 ngcm-2). This was all rather academic anyway because, as the authors admit:

"NNA carcinogenicity has not been reported." 

In other words, the one TSNA they did manage to find in any quantity doesn't cause cancer. 

There is nothing obviously wrong with the way the chemistry was done here. The paper simply shows that nitrous acid (HONO) molecules will react with absorbed nicotine (just as it would with free-floating nicotine) to produce TSNAs. The more HONO in the room, and the more nicotine on the surface, the more the reaction will occur (of course).

The problem (and it's a big problem) is that mixing nitrous acid with nicotine is an experiment with virtually no practical application. If your house or car is full of nitrous acid then you have more to worry about than it reacting with absorbed nicotine. As the authors point out near the top of the 2nd column, 1st page:

"The main indoor sources of HONO are direct emissions from unvented combustion appliances, smoking, and surface conversion of NO2 and NO." 

NO2 and NO themselves are products of unregulated combustion. So you'll only be exposed to high concentrations of HONO if you're exposed to the products of combustion - ie. you're a peasant in a smoke-filled hut, you live in a very polluted city like New Delhi, or you are in fact smoking a cigarette. The combustion products themselves are carcinogens, and are present in much higher concentrations than the TSNAs. Any surface reaction is negligible. Your problem is the nitrous acid, not the TSNAs.

Is this kind of surface reaction likely to take place in the home? Not at all. Nitrous acid concentrations in the average Californian home are 4.6 parts per billion (ppb). This is 14 times lower than the 65 ppb concentrations used in this experiment (which indirectly compares with EPA limits for NO2 of 53 ppb). The chances of HONO and nicotine reacting to create detectable, let alone harmful, concentrations of TSNAs outside of a laboratory experiment are zilch.

In summary:

  • The researchers used concentrations of nitrous acid 14 times higher than would be found in a normal environment
  • Even at the unrealistic levels found in the experiment, there is no evidence that such doses are harmful to humans
  • The main TSNA produced is not a carcinogen
  • The weakest results were found in the real-life conditions, with measurements barely exceeding detectable levels in the smallest conceivable workplace of a heavy smoker
  • Any effect from the TSNAs is negligible compared to the effects of the nitrous acid itself 

* And I thank my bio-chemist friend JPM for his assistance in making it intelligible to me. 


David Strange said...

A great analysis of a really rubbishy piece of science; well done that man! Drawing the conclusion that third-hand smoke is in any way harmful can only happen either because of how impenetrable the paper is or (more likely) that that would be the conclusion some people want no matter what the science actually says.

When erroneous conclusions are drawn from scientific studies it is very important to point out why and how they are wrong. If we don't the neo-prohibitionists will have an easy ride in their quest to restrict our liberties.

Anonymous said...

I am sorry to say the neo-prohibitionists are already having an easy ride, all the way into your home. Just read the comments on the news articles and you will see the number of knee jerk, social authoritarians there are in the world. Of course, they do not see that others with even more extreme versions of their "my way or the highway" view of the world could, at some point, turn around and attack their way of life.

Unknown said...

Great piece Chris, really loved it

Anonymous said...

The third hand smoke scam failed the last two times it was tried on.
Hopefully it will fail this time.
I think and hope that is highly likely ,my gut feeling is it will.
Simply because all the articles I have read ,their seems to be little support for the idea and most see through the ridiculouslness of the claim.
Good example are the comments from the new scientist below.
However ,the problem is Politicians do not seem to be bothered on the validity of claims like this third hand smoke quackery as long as it suits their political agenda.
As for bans in homes ,in private housing that would be impossible to enforce.
However in public housing i.e. rented blocks of flats it would be more enforcable.
I know in "Kalifornia" this is done already.
How succesfull they are in actually enforcing it I do not know.
Going by other opinions I see I think more and more smokers are beginning to wake up to what is hapening to them and hopefully become more politically active.
Rather than putting up with it.
A good example of how to defend yourself was created by the gay community.
A good blue print on how to survive as a minority under attack.
But smokers are quite a large minority 25% ,I think more actually as tobacco use statistics are based on ligitimate sales in the UK.

The idea of third hand smoke is quite nasty.
It basically means they are trying to scare people into thinking that smokers are toxic.
This notion when aligned to the fact that the pseudo science behind it is so bad it is laughable then it bears a strong resemblance to the "HATE CRIME" pseudo science touted by rascists at the turn of the century.
Anti smoking has now gone beyond public health and is behaving in a manner akin to rascist dogma.

Anonymous said...

What happened to the peer review?

Anonymous said...

An excellent post. Many thanks to your bio-chemist. Have you considered trying to get this article published somewhere mainstream? Definitely send it to CRUK.

Anonymous said...

Effect of nitrous acid on lung function in asthmatics: a chamber study

Nitrous acid, a component of photochemical smog and a common indoor air pollutant, may reach levels of 100 ppb where gas stoves and unvented portable kerosene heaters are used. Nitrous acid is a primary product of combustion and may also be a secondary product by reaction of nitrogen dioxide with water. Because the usual assays for nitrogen dioxide measure several oxides of nitrogen (including nitrous acid) together, previous studies of indoor nitrogen dioxide may have included exposure to and health effects of nitrous acid. To assess the respiratory effects of nitrous acid exposure alone, we carried out a double-blinded crossover chamber exposure study with 11 mildly asthmatic adult subjects. Each underwent 3-hr exposures to 650 ppb nitrous acid and to filtered room air with three 20-min periods of moderate cycle exercise. Symptoms, respiratory parameters during exercise, and spirometry after exercise were measured. A statistically significant decrease in forced vital capacity was seen on days when subjects were exposed to nitrous acid. This effect was most marked at 25 min and 85 min after exposure began. Aggregate respiratory and mucous membrane symptoms were also significantly higher with nitrous acid. We conclude that this concentration and duration of exposure to nitrous acid alters lung mechanics slightly, does not induce significant airflow obstruction, and produces mild irritant symptoms in asthmatics.

Anonymous said...

This study appears to be wall to wall junk science. They seem to be most worried about "carcinogenic tobacco-specific nitrosamines or TSNAs..several hundred nanograms per square meter of nitrosamines" (1)

Guess where Nitrosamines are also formed? Cooking fish, where TSNAs are measured in microgrammes, but in the Berkeley paper nanogrammes a factor of a thousand times smaller. (2)

Nitrosamines are also found in ham, milk, children's balloons and tap water. (3)

Finally the World Health Organization's cancer mouthpiece the International Agency Research on Cancer says on Nitrosamines: "5.2 Human carcinogenicity data. No data were (sic) available to the Working Group." (4)

So we have a dose that is so low, cooking a fish produces 1,000 times more "carcinogens" on a chemical which has not been proven to cause cancer in the first place.

Junk science that insults the intelligence.

Anonymous said...

Just a little bit more about the N'-nitrosonornicotine found in SHS/ETS.

However, the dose makes the poison!!

This stuff is NOT present in quantities known to be hazardous!!!

The concentration of N'-nitrosonornicotine (NNN) ranged from not detected to 23 pg/l, that of N'-nitrosoanata-bine ranged from not detected to 9 pg/l, while 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was detected in concentrations ranging from 1 to 29 pg/l.

Thus, non-smokers can be exposed to highly carcinogenic TSNA.

NNN = 0 to 23 picograms per liter

NNK = 0 to 29 picograms per liter

1 cubic meter = 1,000 liters

1 nanogram(NG) = 1,000 picograms

Thus, NNN of 0 to 23 picograms per liter is the same as 0 to 23 nanograms(ng) per cubic meter

NNK of 0 to 29 picograms per liter is the same as 0 to 29 nanograms(ng) per cubic meter.

The question is whether or not 0 to 29 nanograms(ng) per cubic meter of a carcinogenic substance is a dangerous level?

The Department of Health and Human Services (DHHS) has concluded that inorganic arsenic is known to be a human carcinogen.

The International Agency for Research on Cancer (IARC) cites sufficient evidence of a relationship between exposure to arsenic and human cancer. The IARC classification of arsenic is Group 1.

The EPA has determined that inorganic arsenic is a human carcinogen by the inhalation and oral routes, and has assigned it the cancer classification, Group A. c6.pdf
6.4.1 Air

Mean arsenic levels in ambient air in the United States have been reported to range from 20 to 30 ng/m3 in urban areas (Davidson et al. 1985; EPA 1982c; IARC 1980; NAS 1977a).

NOTE: 20 to 30 ng/m3 is NOT stated to be a hazardous level of exposure to this known human carcinogen.

Anonymous said...

these nitrosomines and their group are turned into inorganic arsenic in the body.........

Levels of arsenic in the air generally range from less than 1 to about 2,000 nanograms (1 nanogram equals a billionth of a gram) of arsenic per cubic meter of air (less than 1–2,000 ng/m3), depending on location, weather conditions, and the level of industrial activity in the area. However, urban areas generally have mean arsenic levels in air ranging from 20 to 30 ng/m3.

Both inorganic and organic forms leave your body in your urine. Most of the inorganic arsenic will be gone within several days, although some will remain in your body for several months or even longer. If you are exposed to organic arsenic, most of it will leave your body within several days.

The Occupational Safety and Health Administration (OSHA)
has set a permissible exposure limit (PEL) of 10 micrograms
of arsenic per cubic meter of workplace air (10 μg/m³) for 8
hour shifts and 40 hour work weeks.

Levels of arsenic in food range from about 20 to 140 ppb. However, levels of inorganic arsenic, the form of most concern, are far lower. Levels of arsenic in the air generally range from less than 1 to about 2,000 nanograms (1 nanogram equals a billionth of a gram) of arsenic per cubic meter of air (less than 1–2,000 ng/m3), depending on location, weather conditions, and the level of industrial activity in the area. However, urban areas generally have mean arsenic levels in air ranging from 20 to 30 ng/m3.
You normally take in small amounts of arsenic in the air you breathe, the water you drink, and the food you eat. Of these, food is usually the largest source of arsenic. The predominant dietary source of arsenic is seafood, followed by rice/rice cereal, mushrooms, and poultry. While seafood contains the greatest amounts of arsenic, for fish and shellfish, this is mostly in an organic form of arsenic called arsenobetaine that is much less harmful. Some seaweeds may.

Children are likely to eat small amounts of dust or soil each day, so this is another way they may be exposed to arsenic. The total amount of arsenic you take in from these sources is generally about 50 micrograms (1 microgram equals one-millionth of a gram) each day. The level of inorganic arsenic (the form of most concern) you take in from these sources is generally about 3.5 microgram/day. Children may be exposed to small amounts of arsenic from hand-to-mouth activities from playing on play structures or decks constructed out of CCA-treated wood. The potential exposure that children may receive from playing in play structures constructed from CCA-treated wood is generally smaller than that they would receive from food and water.

Anonymous said...

This opens up the debate about synergism claims about shs/ets indoors.If this is the best claim the antis could come up with then the synergism claim by greg watchman from osha is nothing more than an effort to supply the antis with some sort of reputable claim to fall back on......perhaps we need to push this point home and further throw the antis on defence.

I firmly believe if synergism of other chemicals were actually of concern the antis would have jumped all over it on second hand smoek claims and produced studys to that effect,yet it seems they have instead tried to create a synergism claim with this 3rd hand smoke trash science......obviously there isnt even a threat with super high indoor smoking in an unventilated room as osha pels have shown.

RDP said...

Our good ‘friend’, Big Jarn the ⅓, is very much on the ball with ‘third-hand smoke’:

Some of the content is a thing of literary beauty:
"Fortunately, says Banzhaf, the law provides protection against exposure to this substance, previously simply known simply as "tobacco smoke residue," which also contains heavy metals, hydrogen cyanide (used in chemical weapons), butane (used in lighter fluid), toluene (found in paint thinners), arsenic, lead, and even radioactive Polonium-210 (used to murder a Russian spy)". [emphases added]

Unfortunately, the deranged views of Big Jarn (used to deceive the politicians/media/public) receive much media attention.

Anonymous said...

How on earth is it possible I still live ? My parents smoked My mother smoked when pregnant and when she gave me breast milk ( I am born in 1956 ) All my teachers smoked My doctor smoked In every building people where smoking Both my parents smoked and so did the people who came to visit I smoke since I am 12
So according to all "scientific" proof
I should have died on the age of 38 being largely exposed to second hand smoke Third hand smoke and first hand smoke By God I am a miracle !!!!!!

Ann W. said...

Hi Anna, I was also born in 1956 to a smoking mother. Maybe there is a correlation between our year of birth and both having Ann as our name that protected us from all those 1st,2nd and 3rd toxins?

Michael J. McFadden said...

Beautifully done Chris!You picked up on the same thing I did when reading the study: hidden deep in the bowels of all the bells and whistles there was the basic "assumption" of a HONO level literally 1,500% *GREATER* than you would normally find in people's homes. The "meaning" of this study is just as big a lie as that of the ThirdHand Smoke study done a year ago examined by Dr. Kabat with Aftercomments from me at:

In that case a toddler would have to lick floors for 2.74 TRILLION years to meet the worry-standard set in the New York Times....
But of course the studies and the articles about them never bother mentioning such piddling details, right?

In cases where the basic data and methodology is available and checkable virtually every secondhand (and now Thirdhand!) smoke study that's ever been held up as promoting smoking bans has been shown to be false at one level or another. These things are a disgrace to science and the scientific method and the grant-grubbing researchers who agree to play up such almost imaginary findings as being "dangers" should be drummed out of the League Of Decent Scientists.


Anonymous said...

Great post you got here. It would be great to read more concerning that topic. Thanx for giving that material.

PicassoIII said...

Bravo Christopher,
As usual there is a 'fudge factor' involved somewhere. Nitrous acid levels far beyond what would normally be found. Typical.

Michael J. McFadden said...

The Columbia University Press evidently archives expansions on its articles for a very limited time period. Apologies to any who clicked on that link, although Kabat's article is good in and of itself. You can find my expansion at Global Health Law intact however at:

Meanwhile the craziness has grown. One professor is getting a hundred thousand or so to scrape dust from the floors of smoke chambers and mush it into bleeding injured rats or somesuch (the details of how the "experiment" is set up aren't yet available). Why would someone lay out a hundred grand for this? Simple: she's going to show that "thirdhand smoke" inhibits wound healing.

See my article "Third Hand Smoke Causes Leprosy!" at:

or in the Club Newsletter for Aug. 6th at:


RdM said...

And the madness still infiltrates...

Puffing mums are toxic

No opportunity for public comment - perhaps privately to author or editor!

NB other articles by same author, similar unthinking rubber-stamp collaboration...

Smoke-free aim for bus stops

New strategy: Tell smokers they stink

Smoking: The endgame

Cars next smokefree target

Cuts planned to duty-free tobacco

Oh, the evil!

I note that retail roll-your-own tobacco in NZ is now about the same price as silver on the international market...

Over a dollar per gram... 4-5 times retail European prices, it seems.

Good-bye, tourism - hello, suborned state control ... by TC fiefdom.