Hookah smoking delivers carcinogens and carbon monoxide

The tobacco and fruit mixture smoked in public hookah bars might be considerably more dangerous than its pleasant scent would suggest. An analysis of people who smoked from water pipes three times a day finds that the pipes deliver more carbon monoxide and benzene, a carcinogen, than does smoking half a pack of cigarettes daily.

In an upcoming issue of Cancer Epidemiology, Biomarkers & Prevention, researchers document those and several other cancer-causing compounds that showed up in urine tests of the water-pipe smokers. The research calls into question a common assumption: that hookahs are safe.

“This is a great addition to the literature,” says Thomas Eissenberg, a psychologist at Virginia Commonwealth University in Richmond. He and his colleagues had previously found toxic substances in hookah smoke. The new paper extends his findings by detecting carcinogens and other bad actors in water-pipe smokers themselves, he says.

Hookah smoking goes back hundreds of years in India, the Middle East and North Africa, but it is newer in parts of Europe and North America. The substances heated in a hookah vary. In the study, researchers used pastes chosen by the participants that were 5 to 10 percent tobacco combined with honey, molasses and bits of fruit. This paste goes in the bowl of the pipe, which is covered with a perforated piece of aluminum foil and topped with a burning piece of charcoal, says study coauthor Peyton Jacob III, a research chemist at the University of California, San Francisco. The smoker then inhales.

In the new study, 13 healthy volunteers — all smokers who used both cigarettes and hookahs — smoked only a hookah for four days and then, after a week with no restrictions, only cigarettes. The volunteers averaged three water pipe sessions or 11 cigarettes per day.

Urine tests revealed that the volunteers had higher benzene levels when smoking hookahs than when smoking cigarettes. Benzene inhalation is associated with leukemia and lung cancer. The volunteers’ tests also showed higher levels of pyrene, a polycyclic aromatic hydrocarbon  or PAH, when smoking the hookah. Similar amounts of the probable human carcinogen acrylamide and the PAH phenanthrene showed up during cigarette or hookah smoking. Exposure to PAHs is linked to cancer and immune problems (SN: 3/23/13, p. 19).

Using breath tests, the researchers found that levels of carbon monoxide, a poisonous, odorless gas, were 2.5 times greater in volunteers after the water-pipe sessions than after cigarette smoking. The volunteers’ blood samples while smoking the water pipe showed about half as much nicotine as when smoking cigarettes, but researchers estimated that the level was enough to be addictive.

Carbon monoxide and PAHs have been traced to burning charcoal, Eissenberg says. The contributions from the incompletely combusted paste are less clear.

Water-pipe smoking delivers more smoke per puff, Eissenberg says, because the taste is sweet, the smoke is cooled, and inhaling is easier when a smoker doesn’t have to drag air through a filter or tightly packed cigarette. A 2004 study done in an upper class neighborhood in Beirut found that people take 50 to 200 puffs during a water-pipe smoking session, which lasted 20 to 80 minutes. A cigarette smoker takes eight to 12 during an average smoke, the research found.

In the U.S., three in 10 university students have tried a hookah, Eissenberg and colleagues reported in a 2008 survey. Despite the apparent risks, Eissenberg says, hookah pipes and packages of hookah paste carry no regulatory warnings.

“Many water-pipe smokers tell me they know cigarettes are dangerous,” he says. “It’s written on the pack. They say, ‘I haven’t heard anything about water pipe smoking. It must be safe.’ ”