A study once showed that tobacco through a hookah, during a half hour session, delivered the nicotine equivalent of 3 cigarettes, and the tar equivalent of 30 cigarettes. Hookahs are not designed for inhaling as far as safety goes, you just taste the smoke like with a cigar or pipe.

The smouldering charcoal has a more potent carcinogen than other tobacco forms. I'd use the hookah without charcoal for weed only, like a hosed bong.