Sidestream cigarette smoke more toxic than mainstream smoke

In my last post about tobacco smoke pollution I mentioned the puzzling fact that although exposure to tobacco smoke pollution (TSP or ETS or SHS) gives about 1-5% of the smoke dose of active smoking, it gives a proportionately bigger increase in some disease risks. This fact has caused some to be rather skeptical about the evidence on tobacco smoke pollution and health. But just this month a new paper has been published by Drs Suzaynn Schick and Stan Glanz at University of California at San Francisco, that sheds some new light on this.

One of the main carcinogens in cigarette smoke is known as NNK (as its long chemical name is almost unpronounceable!). Previous studies have shown that there is a 3-4 times higher concentration of NNK in sidestream smoke (the smoke released from a burning cigarette into the air between puffs) than in mainstream smoke (the smoke inhaled by the smoker). But the new paper by Drs Schick and Glanz went further. They analyzed tobacco industry documents dating back to the 1980s that showed that Philip Morris tobacco company (which was, at that time, denying the harmfulness of exposure to environmental tobacco smoke) had conducted studies that not only measured these effects, but uncovered the mechanism behind it (continued reaction of nicotine, nitrogen oxides and other smoke chemicals). These studies also showed that while the smoke ages as it hangs in the air in a room where someone has smoked, the concentration of NNK actually increases another 2-4 times! So the net effect is that the concentration of NNK per unit of sidestream smoke hanging around in the air in a room hours after the smoker has left, may be 10 times greater than the concentration per unit of smoke the smoker inhaled directly from the cigarette. This type of finding may be a part of the explanation of why exposure to tobacco smoke pollution is more harmful than we might expect from the simple amount of smoke being inhaled.

Of course the tobacco company that discovered these results (Philip Morris, makers of Marlboro) did not expend much effort to share them with the public. Rather, it has taken painstaking research by public health scientists to piece together the evidence from tobacco industry documents and publish them in a peer-reviewed journal.

This gives yet more reason to ensure that people (and pets) in public spaces should not be exposed to tobacco smoke pollution, and to make sure your home environment is smoke-free.

This link takes you to the original journal report:
http://cebp.aacrjournals.org/cgi/content/abstract/16/8/1547

Labels: ETS, pollution, SHS, Smoking, tobaco

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