According to UCLA researchers Arthur Brody et al, it might do, because exposure to secondhand cigarette smoke can cause you to absorb enough nicotine that it has measurable effects in the brain.That's quite interesting, but the best thing about this study is the methodology. This is the first neuroimaging study I've seen which involved a car. Not a picture of a car. An actual car.
They used PET scanning to measure the binding of nicotine to brain nicotinic acetylcholine receptors (nAChRs), the major target of the drug. They first injected people with a radioactive tracer compound, in this case a nicotine-like molecule which binds to nAChRs. Because nicotine binds to the same target, it displaces the tracer and reduces the radioactive signal from the brain.
Where did the car come in? Well, volunteers were scanned before and after sitting in a car for one hour, next to a smoker who smoked cigarettes over the course of the hour. An average of 3.7 cigarettes to be precise. The windows were closed to keep the car nice and smoky.
The scene was made even more remarkable by the fact that the subject was still being injected with the tracer compound during this period: they were attached to a drip which went through a little gap in the window and outside. Sadly, they don't show us any pictures...
Anyway, they found that secondhand smoking did cause modest but significant binding to the receptors. The graph shows tracer binding in four areas of the brain - the lower the line, the more nicotine. After secondhand smoke, the lines go down.
After sitting in a "placebo car" in which no-one was smoking, however, there was no effect (the empty circles.) Then later on, the participants were able to smoke some cigarettes first-hand: this had a much stronger effect as you'd expect.
The effect of secondhand smoke was pretty large, though. Actual smoking led to nicotine receptor occupancy of about 50%. Secondhand smoke weighed in at about 20%. Interestingly, in the participants who were regular smokers themselves, the secondhand smoke made them report increased cravings for a cigarette - and this correlated with secondhand smoke nicotine binding (though only in one area of the brain.)
Is this a realistic study? I can't imagine many smokers sit smoking inside their car with the windows up for hours on end. If nothing else because it make their car smell all smoky. (Did they have to pay for the car? If so, this might be the only legitimate example of someone buying themselves a new car using their research grant money...) But the authors say that being in a room with multiple smokers would lead to even higher levels of smoke.
Brody AL, Mandelkern MA, London ED, Khan A, Kozman D, Costello MR, Vellios EE, Archie MM, Bascom R, & Mukhin AG (2011). Effect of Secondhand Smoke on Occupancy of Nicotinic Acetylcholine Receptors in Brain. Archives of general psychiatry PMID: 21536968
10 comments:
Despite a policy that no one is to smoke in company vehicles several employees where I work do anyway. They do a lot of driving and do indeed smoke hours on end and their vehicle’s definitely smell of stale cigarettes. Windows are often not opened because of traveling at highway speeds and because it is so hot here in the summer (Southern U.S.) An anecdote, I know, but there are at least some smokers who do not care if they bother their passengers or smell up their vehicles.
Childhood memories of my sisters and me, pulling the necks of our shirts over our noses in the car during sweltering summers and wind-whipped winters, when our chain-smoking mother was at the wheel. We would have taken $10 each for being study victims...
My childhood memories from Scotland are of everybody smoking, seemingly all the time, everywhere.
I remember going to visit my uncle in the cancer ward at the Royal Infirmary in Glasgow, where the bedside tables all had ash-trays. And the nurses, matrons, and doctors all smoked too.
We didn't have cars then, but our homes were smoked-filled, from cigarettes, cooking, and coal fires.
Some US agency did tests in the netherlands on the influence of pot on driving since there it's legal to smoke.
Some students had a whale of a time.
No PETscan though :)
Finally I know what "secondhand smoking" is -- it is not just being nearby a smoker: you must really go through all of his/her exhaust, and then again through the exhaust of you both, and so on, for an hour or so.
I'm genuinely puzzled by results like these. If the % for the amoker and 20% for the non-smoker, then a crude calculation suggests that the dose of nicotine for the non-smoker might be around 25% - 50% of that for the smaker (taking Hill coeffient between 1 and 2).
Is it really possible that even under these rather extreme conditions, the non-smoker gets as much as half the dose that the smoker gets?
Try again. I'm genuinely puzzled by results like these. If the occupancy is 50% for the amoker and 20% for the non-smoker, then a crude calculation suggests that the dose of nicotine for the non-smoker might be around 25% - 50% of that for the smaker (taking Hill coeffient between 1 and 2).
Is it really possible that even under these rather extreme conditions, the non-smoker gets as much as half the dose that the smoker gets?
2David: why not? could be even more extreme since I bet smoker had sigarette's with filter I bet, thus at least he had some protection ! ;)
I grew up in a household full of smoke. Although I don't think I ever felt high off second hand smoke I always thought it effected my health. I had horrible allergies as a child. When I moved out two things happened. First, I realized that all my cloths smelled like smoke and no matter how many times I washed them they still smelled of smoke. I threw out most of my clothes which really sucked. :-) Second, my allergies slowly subsided. I guess I'll never know how much I was effected by second hand smoke. Great blog. I am really enjoying your posts. :-)
You've mentioned about a room with a lot of smokers in it, right? That car was perhaps an "ideal" controlled environment. Knowing that smoking is already that dangerous as it is in any environment, what more if it's in a small room? Would alternatives like e-cigarettes and the like be able to prevent such hazards?
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