Being exposed to second hand smoke, also known as passive smoking - non-smokers breathing in smoke from lit cigarettes around them - may significantly increase the long-term risk of developing lung disease, such as lung cancer and COPD (chronic obstructive pulmonary disease), according to a report published in the American Journal of Respiratory and Critical Care Medicine. The same applies to casual (occasional) smoking.
This is the first study to demonstrate what passive or occasional smoking does to the body at a gene function level, say the authors.
Study author, Dr. Ronald Crystal, head of pulmonary and critical care medicine at NewYork-Presbyterian/Weill Cornell and chair of the department of genetic medicine at Weill Cornell Medical College in New York City, said:
Even at the lowest detectable levels of exposure, we found direct effects on the functioning of genes within the cells lining the airways.
The genes which are usually activated in the cells of regular heavy smokers may also be turned on/off in individuals with very low-level exposure, Dr. Crystal explained.
Dr. Crystal added:
The genetic effect is much lower than those who are regular smokers, but this does not mean that there are no health consequences. Certain genes within the cells lining the airways are very sensitive to tobacco smoke, and changes in the function of these genes are the first evidence of 'biological disease' in the lungs or individuals.
The researchers tested 121 individuals from three different categories:
- Currently active regular smoker
- Low exposure smokers
Each participant's entire genome was scanned to find out which genes were either activated or deactivated in the cell linings of the airways. The researchers discovered that there was no level of nicotine or cotinine that did not also correlate with genetic abnormalities.
Dr. Crystal said:
This means that no level of smoking, or exposure to secondhand smoke, is safe.
Dr. Crystal added that the genetic changes act like a canary in a coal mine warning of latent life-threatening conditions and diseases..
..but the canary is chirping for low-level exposure patients, and screaming for active smokers.
This is further compelling evidence in favor of banning smoking in public places where non-smokers may be at risk of future lung disease, Dr. Crystal says.
Second hand smoke - also known as passive smoking or environmental tobacco smoke (ETS) is environmental tobacco smoke that is inhaled involuntarily by a non-smoker.
"Threshold of Biologic Responses of the Small Airway Epithelium to Low Levels of Tobacco Smoke"
Yael Strulovici-Barel, Larsson Omberg, Michael O'Mahony, Cynthia Gordon, Charleen Hollmann, Ann E Tilley, Jacqueline Salit, Jason Mezey, Ben-Gary Harvey, and Ronald G Crystal
Am. J. Respir. Crit. Care Med. 2010, doi:10.1164/rccm.201002-0294OC
Written by Christian Nordqvist