The liquids are usually made of: propylene glycol (a food safe additive), glycerine, nicotine and flavoring (the same kind used in food). Nicotine, while not co

The liquids are usually made of: propylene glycol (a food safe additive), glycerine, nicotine and flavoring (the same kind used in food). Nicotine, while not completely benign, is not exactly deadly stuff at the concentrations used in ecigs; it's in the same ballpark as caffeine. Propylene glycol and glycerine are well studied and safe. The "unknown" part is whether or not the food flavorings (which are safe to ingest) are also safe when vaporized. Probably, but not all of them have been tested, so there can't be a guarantee. So there are no known special health risks apart from those from the nicotine, and no particular reason to believe that there are any. The superficial ressemblence with the act of smoking is what makes people afraid of ecigs, and in reaction the public is pushing a rather unfair burden of proof onto the ecig industry. As for whether it can be used to deliver other substances than nicotine; I'm not really sure I follow your question. Do you mean whether someone could use it to vape pot? If that's what you want to know, well there are ways to make hash oil that can be used in an ecig, but apparently it's a big hassle; most would prefer buying a dry herb vaporizer and would use that instead. If you want to know if there a guarantee as to the content of the liquid used, not exactly. You could buy Chinese made liquid (Dekang and the like), of which I would be very wary. But most vapers I know buy liquid from small domestic businesses. Personally, I have talked with and met the very people who make the liquid I use. If I did not trust them, I could even make it myself: all of the ingredients are easy to find, and mixing them require little equipment. The biggest risk to the ecig industry is that overly zealous regulation will remove the small players from the industry, leaving only the large corporations. Many of whom would be tobacco companies, which have an incentive to keep people smoking rather than vaping.