Cigarette Smoke Harms Lung Genes, Even at Low Levels
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
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.