TUESDAY, July 24, 2001 (HealthDayNews) -- Secondhand smoke takes only 30 minutes to damage your body, a new Japanese study shows.
The sensitive endothelial tissue that lines your blood vessels begin to malfunction after that brief exposure, causing the same reduced blood flow experienced by chronic smokers, report researchers at Osaka University Medical School reports in tomorrow's Journal of the American Medical Association.
"This provides direct evidence of a harmful effect of passive smoking on the coronary circulation in nonsmokers," the researchers say.
The effects of secondhand smoke on the lungs and the heart have been the subject of continuing controversy. The American Heart Association (AHA) estimates that exposure to secondhand smoke in the home increases the risk of death due to heart disease by 30 percent, while the tobacco industry says the effects are insignificant.
"We do not believe the scientific evidence concerning secondhand smoke establishes it as a risk factor for lung cancer, heart disease or any other disease in adult nonsmokers," says Seth Moskowitz, a spokesman for the R. J. Reynolds Tobacco Co.
But Dr. David P. Faxon, president of the AHA and chief of cardiology at the University of Chicago, says, "We believe there is a risk, and this study offers evidence for that."
The Osaka researchers used a technique called Doppler echocardiography to measure coronary flow velocity reserve (CFVR) in 15 nonsmokers and 15 healthy smokers in their 20s. CFVR is an index of how well endothelial cells function. When they malfunction, blood vessels narrow, decreasing blood flow and accelerating atherosclerosis, the hardening of the arteries that leads to heart disease.
Measurements taken before the test showed the nonsmokers had a significantly higher CFVR than the smokers, 4.4 compared to 3.6, the researchers say. After 30 minutes of breathing smoky air, CFVR was unchanged in the smokers but dropped to 3.4 in the nonsmokers.
"Prior studies have shown that the risk exists. This clarifies the mechanism," says Faxon.
On a practical level, the argument about the effects of secondhand smoke has been fought in battles over laws restricting smoking in restaurants and other public places. All but one of the 50 states have such laws, Faxon says.
"There is a controversy about them, but not in the American Heart Association," Faxon says.
What To Do
Don't smoke, of course, but also avoid secondhand smoke at home, at work and in restaurants.
The AHA provides information about secondhand smoke. For an industry view, go to R. J. Reynolds Tobacco Co..
