FRIDAY, Aug. 20 (HealthDay News) -- A drag from a cigarette now
and then can't hurt, right?
Wrong, according to a new study that finds even low levels of
smoke exposure can cause irreparable damage to cells essential to
The damage occurred among "casual" smokers and even after
exposure to secondhand smoke. The initial damage, while not usually
severe, can be cumulative and prolonged exposure to tobacco smoke
could lead to chronic obstructive pulmonary disease (COPD) and even
lung cancer, the researchers reported.
"It has been known for a long time that secondhand smoke or smoking occasionally can be risky for your health," said study author Dr. Ronald Crystal, chief of the division of pulmonary and critical care medicine at NewYork-Presbyterian Hospital/Weill Cornell, in New York City.
Just how much a little exposure might damage airway cells hasn't
been clear, however.
"We found that if we could detect nicotine in the urine we could also detect changes in the genes in the cells lining the airways," said Crystal, who is also chair of the department of genetic medicine at Weill Cornell Medical College.
The bottom line: "There is no level of cigarette smoking or
exposure to cigarette smoke that does not make the cells in your
lungs sick," he said. "If you are an occasional smoker you are
still at risk. Don't think that smoking one or two cigarettes a
week means you are home free."
As for secondhand smoke, "if you are working in a place where
people smoke, either get them to stop or go get another job,"
Crystal advised. "If you have somebody at home who smokes, send
them outside to smoke. Don't be exposed to secondhand smoke."
The report is published in the Aug. 20 issue of
American Journal of Respiratory and Critical Care
For the study, Crystal's team recruited 121 people who were
nonsmokers, active smokers or low-exposure smokers. To determine
who belonged in which group, all participants had their urine
tested for levels of nicotine.
Crystal's group next scanned each person's entire genome to
determine whether genes governing airway cells were turned on or
They found that there was no level of nicotine or cotinine, no
matter how small, that did not produce genetic abnormalities.
"These cells are like canaries in the mine, they're crying out for help -- this gene is being turned on, this gene is being turned off," Crystal said. "This now gives us clues to what are the earliest events in terms of what makes our cells go wrong and is the start of these lung diseases, like COPD and lung cancer."
Knowing which genes are damaged could provide targets for new
drugs that could protect the lungs, Crystal said.
Dr. Norman H. Edelman, chief medical officer at the American
Lung Association and a professor of preventive medicine, internal
medicine and physiology & biophysics at Stony Brook University
in New York, applauded the study. "I like this one because it
cleverly uses molecular biology to answer a very important
question, one that I get asked very often ... 'Is there a threshold
below which inhalation of tobacco smoke is safe?'" he said. The
question is usually asked as, " Is it safe to smoke a few
cigarettes a week?" or, "Is it safe to hang out with smoking
friends a few times a week?" Edelman added.
"Within the limits of their detection methods, the answer is 'no,'" Edelman said. "Whether the changes they see in folks with minor exposure will eventually lead to disease is unclear, but it is getting more and more clear to me that there really is no totally safe level of tobacco exposure."
For more information on secondhand smoke, visit the
U.S. National Library of Medicine.