The consensus among medical professionals is that no method of smoking tobacco is safe, and that smoking Hookah is as dangerous as smoking cigarettes. Each hookah session typically lasts more than 40 minutes, and consists of 50 to 200 inhalations that each range from 0.15 to 0.50 liters of smoke.
In an hour-long smoking session of hookah, users consume about 100 to 200 times the smoke of a single cigarette; in a 45-minute smoking session a typical smoker would inhale 1.7 times the nicotine of a single cigarette. The water used to filter the smoke does not remove harmful cancer-causing chemicals from the smoke as is believed by some. There is a new trend turning away from nicotine and tobacco-based products and instead towards herbal molasses. These taste very similar but mitigate the harmful affects.
A study on hookah smoking and cancer in Pakistan was published in 2008. Its objective was "to find serum CEA levels in ever/exclusive hookah smokers, i.e. those who smoked only hookah (no cigarettes, bidis, etc.)."The study showed no statistically significant difference between CEA levels in a hookah smoker and a non-smoker, while levels of cigarette smokers were comparatively raised. The study also concluded that heavy hookah smoking (2–4 daily preparations; 3–8 sessions a day; 2 to 6 hours net daily smoking time) substantially raises CEA levels.
Yeah, if you smoke Hookah 3-8 times a day, 2-6 hours, then duh! What'd you expect it to do? Honestly, if you're smoking that much Hookah, you have entirely too much free time on your hands and need to pick a better, safer hobbie; Like exercise, or anything to get you off your ass and away from a damn Hookah.