Almost 1 in 5 senior high school students in the US report using hookahs to smoke tobacco in the past year, according to a new study published in the American Journal of Preventive Medicine.

Share on Pinterest Researchers found almost 20% of senior high school students reported hookah use in the past year.

What is more, more than a third of these students say they use hookahs frequently enough to be deemed regular users.

According to study leader Dr. Brian A. Primack, of the Center for Research on Media, Technology and Health at the University of Pittsburgh, PA, and colleagues, their research provides further evidence that hookah use among teenagers is on the rise in the US.

“Hookah smoking does not seem to be just a fad; it seems to be a practice that is increasing steadily over time nationwide,” says Dr. Primack. “And, among hookah smokers, it’s not just something they do once and that’s it. A substantial and increasing proportion of people, particularly adolescents, seems to be smoking hookahs with enough regularity to create a significant public health concern.”

Hookahs, also referred to as water pipes, narghile or shisha, are devices used to smoke flavored tobacco. While popular belief holds that hookah smoking is less harmful than cigarette smoking, research has found it poses similar risks to health, linking it to conditions such as cardiovascular disease and lung and oral cancers.

Hookah smoke contains many of the same toxic chemicals as cigarette smoke – such as tar, nicotine, carbon monoxide and polycyclic aromatic hydrocarbons – and due to the way hookahs are used, smokers may also inhale more of these toxic chemicals than cigarette smokers.

According to the Centers for Disease Control and Prevention (CDC), hookah users inhale around 90,000 milliliters (ml) of smoke per session, while cigarette smokers inhale around 500-600 ml per cigarette.

Last year, a study reported by Medical News Today found hookah use increases uptake of a substance called benzene, which is associated with greater risk of leukemia.