MONDAY, May 23, 2005 (HealthDay News) -- The average nonsmoker walking into a smoke-filled room might not think short-term exposure to cigarette smoke will affect them.
But a new study suggests that even small amounts of secondhand smoke can cause life-threatening changes to a nonsmokers' circulatory system.
And while the immediate effects of this exposure are reversed within a few hours, exposure to secondhand smoke over longer periods of time can have devastating consequences to the heart, including an increased risk for heart attack, researchers warn.
"Secondhand smoke is even worse than we thought," said co-researcher Stanton A. Glantz, a professor of medicine and longtime antismoking advocate at the University of California, San Francisco. "It increases the risk for an acute coronary event like a heart attack or long-term development of atherosclerosis," he added.
Chronic exposure to secondhand smoke is about 80 percent as deleterious to health as being a pack-a-day smoker, Glantz said. "The cardiovascular system is exquisitely sensitive to the toxins of secondhand cigarette smoke. Most of the toxic effects of secondhand smoke occur within five minutes of exposure," he noted.
In their study, Glantz and his colleague Dr. Joaquin Barnoya, an assistant adjunct professor of epidemiology at UCSF, reviewed the existing medical literature on the effects of secondhand smoke on the cardiovascular system. They looked at 29 studies published since 1995 that compared the effects of secondhand smoke with the effects of active smoking.
Their report appears in the May 24 issue of Circulation.
Glantz and Barnoya found there is sufficient evidence that key aspects of cardiovascular function, including clotting, the ability of blood vessels to change size, arterial stiffness, atherosclerosis, oxidative stress, inflammation, heart rate variability, energy metabolism, and severity of heart attack are all sensitive to toxins found in secondhand smoke.
"The effects of even brief (minutes to hours) passive smoking are often nearly as large (averaging 80 percent to 90 percent) as chronic active smoking," they wrote.
"It doesn't take much to cause big effects," Glantz said. "If you already have compromised coronary circulation and go into a smoky environment, there is a substantial increase in your risk of an acute event."
Barnoya believes the findings belie what the tobacco industry would have people believe. "The arguments from the tobacco industry have been that it is not likely that you can find such large effects in passive smokers, given the dose they get compared with the dose an active smoker gets," he explained.
But nonsmokers are more sensitive to the effect of tobacco smoke than are active smokers, Barnoya said. "In some cases, the effects are as large or even larger than you see in an active smoker."
The dangers of secondhand smoke are so great that Barnoya believes everyone should avoid it. "We should be fighting for smoke-free environments," he stressed.
Other experts not involved in the study are unanimous in their agreement of the dangers of secondhand smoke.
"Secondhand smoke disables and kills many people by virtue of its cardiovascular effects and also by virtue of its effects on the lung," said Dr. Norman H. Edelman, chief medical officer for the American Lung Association.
Another expert sees secondhand smoke as an assault on the health of nonsmokers. "How can any society allow tobacco smoke to be imposed on innocent bystanders?" asked Dr. David L. Katz, an associate clinical professor of public health and director of the Prevention Research Center at Yale University School of Medicine.
"We have clear, convincing evidence that those who smoke are swinging a big stick indeed at the noses of those of us who don't," Katz said. "While they should have autonomy over their choices, they should not have autonomy over ours. Smoking in public places does not stop where my nose begins and therefore, it should be banned. Not just by some states, but by all. This study will, I hope, help cultivate the political will to see that job is done sooner rather than later."
Requests for a response from cigarette maker Philip Morris Inc., were not answered at press time.
The American Heart Association can tell you more about the dangers of secondhand smoke.