Second had smoke exposure has shown deleterious health effects to such an extent that public-health bans on smoking. Low level exposure to cigarette smoke leads to higher incidence of lung diseases such as emphysema and even lung cancer. But the biological mechanism was never clear -- until now.
Apparently there are significant genetic changes that occur in lung tissue even with low levels of tobacco smoke exposure.
Aug. 20, 2010 -- Even low levels of tobacco smoke exposure pose a risk to lung health, triggering potentially hazardous genetic changes, according to a new study.
The hazards of secondhand smoke have been known for years, says researcher Ronald Crystal, MD, chief of the division of pulmonary and critical care medicine at New York-Presbyterian/Weill Cornell Medical Center and chair of genetic medicine at Weill Cornell Medical College, New York. ''But there were never any studies that had looked at the biology, why this is the case."
His study does that, demonstrating that even the lowest levels of smoke exposure lead to genetic changes at the cellular level in the lungs. "What this study shows is, if we could detect nicotine in the urine, we could also detect changes in the number of genes turned on and off'' in the cells of the lungs, Crystal tells WebMD.
The new findings put ''scientific teeth" behind the epidemiological evidence that smoke exposure even at low levels is hazardous, says Zab Mosenifar, MD, a pulmonologist, director of the Women's Lung Institute, and executive vice-chair of the department of medicine, Cedars-Sinai Medical Center, Los Angeles, who reviewed the study findings for WebMD.
Even Low Tobacco Smoke Exposure Is RiskyThese researchers removed airway cells from the volunteers using a bronchoscope and tested all 25,000 identified human genes in them to determine which ones were active — either turned on or off — in response to cigarettes. They narrowed the search to 372 genes that were active among the smokers but not in the cells of the nonsmokers. Based on the level of nicotine in the urine, the scientists also divided the volunteers into three groups: smokers, who showed the highest level of the tobacco metabolites; nonsmokers, who showed none of these compounds and a low-exposure group who fell in between. Comparing the 372 genes among these three groups, they found that the low-exposure group shared 34% of the same active genes with nonsmokers and 11% of the same gene activity with smokers. The low-exposure group included both nonsmokers who have never lit up as well as those who admitted to smoking only occasionally.
It's not clear how permanent these genetic changes are, but previous data suggests that, at least in smokers, some of the alterations may be irreversible.
Read more:
http://www.time.com/time/health/article/0,8599,2012103,00.html#ixzz0xFimVJkbHow Secondhand Cigarette Smoke Changes Your Genes
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