UC Irvine Study: Hookahs More Unsafe Than Other Forms Of Smoking

ORANGE COUNTY, CA -- One draw from a waterpipe can contain as many noxious substances as smoke from an entire cigarette, according to the results of a recent study by researchers at the University of California, Irvine.

UCI chemists made the discovery while using a custom-built testing apparatus with which they analyzed emissions during a typical communal waterpipe session. The results were released by the university Aug. 12. The results were published recently in Aerosol Science and Technology.

“Hookah mainstream smoke – that which is directly inhaled by the user – has many toxic and harmful chemicals, such as nicotine, which can lead to tobacco addiction; irritating carbonyl compounds; and benzine, a known carcinogen,” according to the study's lead author, Veronique Perraud, a UCI assistant project scientist in the Department of Chemistry. “And due to the greater volume inhaled for every puff and the longer duration of a smoking session, the hookah oftentimes delivers a higher dose of those chemicals to the smoker.”

The waterpipe also produced an outsized quantity of carbon monoxide, mainly from the burning of charcoal to heat the tobacco or herbal mixture in its bowl. The study refers to several cases in which hookah users have suffered from CO intoxication.

In addition to testing ordinary tobacco, the group studied a nicotine-free herbal mixture, marketed as a healthier alternative, and discovered that it had even higher levels of toxic gases present in the mainstream smoke.

While previous studies have detailed the risks of the hookah habit, the UCI project is the first to characterize ultrafine particles – those with a diameter smaller than 100 nanometers – in the inhaled smoke. Using a pair of mass spectrometers, including a unique instrument designed by the Smith Group at UCI, the scientists measured the chemical composition of both gases and solids emitted during a hookah session in real time, a key differentiation from past studies.

“One of the big myths about hookah usage is that the water in the bowl actually filters out the toxic chemicals, providing a shield for the smoker,” Perraud noted. “In the study, we show that this is not the case for most of the gases and that, possibly due to its cooling effect, water actually promotes ultrafine particle formation.”

Perraud’s UCI co-authors are chemistry professor Sergey Nizkorodov; Michael Lawler, an assistant project specialist in chemistry; Kurtis Malecha, a former graduate student researcher in chemistry; Rebecca Johnson, a graduate student researcher in community & environmental medicine; David Herman, a graduate student in community & environmental medicine; Norbert Staimer, a former associate project scientist in epidemiology; Michael Kleinman, adjunct professor of community & environmental medicine; and chemistry professor James Smith.