The addictive drug can boost your cognition and won’t give you cancer, but that doesn’t mean it’s safe for casual use

"The hazard to health arising from long-term vapour inhalation from the e-cigarettes available today is unlikely to exceed 5% of the harm from smoking tobacco."

"It became clear that it was not nicotine vaping that was implicated. Details were slow to emerge because the substances involved were in fact cartridges containing cannabis (primarily tetrahydrocannabinol or THC). These were often obtained on the illicit market, and in some cases being used by children. This meant users were reluctant to admit what they had vaped.

Excellent review of Nicotine addiction and its biology.

both light cigarettes and regular cigarettes impair blood flow through the coronary arteries to a similar degree. They add that many smokers switch to low tar, low nicotine cigarettes in the mistaken belief that they will reduce some of the hazardous effects of smoking

The two take-home messages are that very little nicotine is needed to occupy a substantial portion of brain nicotine receptors," Brody said, "and cigarettes with less nicotine than regular cigarettes, such as 'light' cigarettes, still occupy most brain nicotine receptors. Thus, low-nicotine cigarettes function almost the same as regular cigarettes in terms of brain nicotine-receptor occupancy.

One shisha is equivalent of a pack of cigarettes in one typical 30-60 minute session with a waterpipe