The research only looks at a single toxic gas, making it impossible to directly compare hookah use to the well-known hazards of cigarette smoking. Still, the findings suggest that hookah fans should think twice before lighting that pipe, said study co-author S. Katharine Hammond, chairwoman of the division of environmental health sciences at the University of California, Berkeley.
"This is not the risk-free activity they think it is," Hammond said. "This really isn't safe."
Hookahs, which are similar to the bongs used to smoke marijuana, have grown in popularity in recent years. In college towns and elsewhere, hookah bars have appeared that allow people to smoke the water pipes - which are legal since tobacco is used - in a public and social setting.
Users inhale tobacco smoke after it bubbles through water, a process that some people think filters toxins from the tobacco.
Popular among students
One survey suggested that 28 percent of first year students at a private university had tried hookahs, Hammond said, adding that Chicago alone has dozens of hookah bars.
"This is a worldwide phenomenon," she said. "It's very popular on US college campuses, but most professors are unaware of it."
The new study is the latest research to suggest that hookahs are far from healthy.
Hammond and a student recruited 27 students who smoked water pipes for an hour on three different evenings in April 2006. Another five students didn't smoke the hookahs, but stayed in the room with those who did.
The participants abstained from water pipe smoking for 84 hours before taking part in the study; the bowls of their water pipes were filled with water and 10 grams of Al Fakher mu'assal tobacco, then heated with charcoal.
Researchers monitored carbon monoxide in the breath of the participants both before and after the experiment using a machine designed to detect if people are smokers.
The exhaled carbon monoxide in participants was an average of 42 parts per million, higher than that reported in cigarette smokers (17 parts per million). The study also found that carbon monoxide levels grew in the room where the subjects smoked hookahs and might reach environmentally unhealthy levels, as determined by the federal government, during longer sessions.
Hammond said she can't directly compare hookah use to the smoking of cigarettes, which house thousands of toxic chemicals. And, she said, it's hard to know exactly what hookah use will mean in terms of higher risk of lung or heart disease.
Hookahs "may not give you lung cancer, but may compromise your health in other ways," she said.
Thomas Eissenberg, an associate professor of psychology at Virginia Commonwealth University who studies hookah use, said research has suggested that smoking a water pipe for 45 minutes produces 36 times more tar than smoking a cigarette for five minutes. Tar - or "nicotine-free, dry particulate matter" - contains the cancer-causing constituents of the smoke, although it's not clear if water pipe tar is different from cigarette tar, he said.
"Occasional water pipe tobacco smoking may carry its own health risks, and it may also be dangerous, because it can lead to daily water pipe use, regular cigarette smoking, or both," he said. - (Randy Dotinga/HealthDay News)
Source: Journal of the American Medical Association.