Casual tobacco smoking and secondhand or passive smoking can do more harm than previously thought, according to a new study which found even low levels of exposure to cigarette smoke can alternate the function of genes implicated in lung diseases.
Researchers at Weill Cornell Medical College of Cornell University and Presbyterian Hospital found that exposure to cigarette smoke at low levels either through passive smoking or infrequent tobacco smoking raised risk for future lung diseases including lung cancer and respiratory disease like chronic obstructive pulmonary disease or COPD.
The study published in the American Journal of Respiratory and Critical Care Medicine is considered the first to demonstrate that passive smoking and infrequent tobacco smoking, which are considered minor sources of cigarette smoke, can affect the body at a genetic function level even though it has been known for long that secondhand smoking is dangerous.
Dr. Ronald Crystal and colleagues said genes that are activated in the cells can also be turned on or off by exposure to low levels of cigarette smoke.
For the study, the researchers tested 121 people for levels of nicotine and cotinine in urine samples, which are markers of cigarette smoke in the body and based on the levels of the markers, participants were grouped into different categories, nonsmokers, active smokers and low exposure smokers.
They then scanned the entire genomes of the participants to see which genes were activated or deactivated in cells lining the airways. They found any level of nicotine or cotinine correlate with genetic abnormalities, meaning exposure to cigarette smoke either through passive smoking or infrequent smoking can cause injury to the cells.
“This means that no level of smoking, or exposure to secondhand smoke, is safe,” said Dr. Crystal.
Secondhand smoke also known as environmental tobacco smoke consists of at least 250 toxic chemicals including more than 50 carcinogens or cancer-causing agents.
Passive smoking affects an estiated 126 million nonsmokers in homes, vehecles, workplaces and public areas in the United States, according to the Centers for Disease Control and Prevention.
Passive smoking has been linked to a whole spectrum of serious diseases including tuberculosis, cardiovascular disease, pancreatic cancer, diabetes mellitus, respiratory infections, kidney disease, acute stroke, acute heart attack or myocardial infarction, and atherosclerosis.