Cigarette Smoke Harms Lung Genes, Even at Low Levels

Kathleen Blanchard's picture
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Avoiding cigarette smoke altogether may be more important than previously known. New findings show that cigarette smoke, even at the lowest levels, can damage the way genes function in the lungs.

Dr. Ronald Crystal, senior author of the study and chief of the division of pulmonary and critical care medicine at New York-Presbyterian/Weill Cornell and chair of the department of genetic medicine at Weill Cornell Medical College in New York City says, "Until now there was no evidence that low level cigarette smoke exposure affected genes in the lining of the lungs.”Even at the lowest detectable levels of exposure, we found direct effects on the functioning of genes within the cells lining the airways."

For heavy cigarette smoker the effect is worse, but Dr. Crystal explains even the lowest level of exposure to cigarette smoke has important consequences that support the need for smoking bans.

No Level of Cigarette Smoking or Exposure is Safe

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The harm to lungs that comes from even low levels of cigarette smoke was found by measuring levels of nicotine and cotinine in the urine of 121 smokers. -- both of which are markers of cigarette smoking within the body.

The researchers then classified the study participants into three groups - “nonsmokers," "active smokers" and "low exposure smokers." They then determined which genes were activated or deactivated in the cells that line the airways of the lungs, finding that no level of exposure or infrequent cigarette smoking is safe.

Dr. Crystal explained the difference between active smokers and the lowest levels of exposure to cigarette smoke is like a "canary in a coal mine, but the canary is chirping for low-level exposure patients, and screaming for active smokers."

The findings show that even the lowest level of exposure to cigarette smoke increases the risk of future lung disease such as COPD and cancer, and is the first study to show biological changes in genes in response to nicotine exposure. Second-hand smoke is known to be dangerous, but the study is the first to show that even the lowest level of cigarette smoke from exposure or infrequent smoking deactivates genes that protect from lung disease, supporting the need for smoking bans and avoidance of even an occasional cigarette.

Weil Cornell Medical College

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Comments

The senior author of this new study is quoted: "Until now there was no evidence that low level cigarette smoke exposure affected genes in the lining of the lungs." and the article goes on to say he explains that "even the lowest level of exposure to cigarette smoke has important consequences that support the need for smoking bans." Really? Just being EXPOSED to smoke? The reporter should have been more careful and gone beyond the misleading press release stage. Even spending five minutes looking over the actual study with a critical eye would have revealed that the way its results are being presented is little better than outright fraud. The study used 3 subgroups:"Healthy nonsmokers, healthy smokers, and healthy individuals exposed to low levels of tobacco smoke." Now most reasonable people would think that the third category was composed of nonsmokers exposed to smoke, right? Wrong. Buried on page 6 the study makes a single mention of an overwhelmingly important fact: "The low level exposure group included self-reported never smokers (8/36) and those who reported some smoking (28/36)." In case you missed it, that means that 28 of the 36 "individuals exposed to low levels of tobacco smoke" were actually SMOKERS! Only 8 were actually true nonsmokers with ETS exposure. Figure 2B at the study's end shows it even more clearly with the nonsmoking group all clustered up in one little area, and right next to them showing almost exactly the same lack of "effect" are the 8 little nonsmokers in the "low exposure group." Despite the public presentation the reality of the data does NOT seem to support smoking bans. Any "risk" worthy of the term seems to begin only with light smokers, not ETS-exposed nonsmokers. Why did the study lump ETS-exposed individuals in with light smokers? The only reason I can think of is in order to produce a result that would allow them to confuse the two and thereby "support the need for smoking bans." Michael J. McFadden, Author of "Dissecting Antismokers' Brains"