BOSTON, Feb. 28 (UPI) -- Many students and young adults say smoking from a hookah, or water pipe, is less harmful than cigarettes, but a U.S. newsletter says it may be more harmful.

Researchers have found that hookah smokers inhale more often and for longer periods than typical cigarette smokers and that puffing longer and in greater volume, a waterpipe smoker inhales the equivalent of 100 cigarettes or more during a single waterpipe session, the March issue of the Harvard Mental Health Letter says.

Proponents of hookah smoking argue that it isn't necessary to inhale the smoke into the lungs because they puff as if on a pipe. However, studies indicate that hookah smokers are absorbing high levels of toxins and carcinogens that may contribute to heart disease, lung cancer and respiratory disease, the newsletter says.

Scientists say although some nicotine is filtered through the water, waterpipe smokers are still exposed to enough nicotine to become addicted, the Mental Health Letter says.