Hi!
Contrary to opinions, the only toxic compound in e-cigs is the nicotine itself. Nicotine is toxic, but has never been shown to be carcinogenic, or a mutagen by itself.
Regarding the FDA, and regulatory stuff, well.. the FDA can go stick it where the sun don't shine, IMO (I was an engineer at a pharmaceutical manufacturer for 4 years)
Nicotine is well quantified, and precisely at stated strengths for every one of the US made e-liquids i've tested.
I make e-juice for friends, family, and myself. The ingredients are: food flavorings (LorAnn, Flavourarts, Fairies Finest.. feel free to google) Propylene Glycol (another food ingredient, mostly found in prepared baked goods, and recognized as safe by the FDA) Vegetable glycerin (again, a widely used and safe for consumption product), and nicotine.
All the PG and VG I use is USP, the Nicotine I use is US sourced, and incredibly pure, and all the flavorings are foodservice flavorings.
Since the vapor produced by an e-cig is fog, not smoke (it doesnt get hot enough) re-condensing vapor from an e-cig you end up with the same liquid you had to start with (but more oxidized, due to the heat and atomization)
Any e-cig supplier worth their salt (and myself included) will not recommend vaping as a smoking cessation tool. You're still putting nicotine into your body..
However, many vapers (including myself) found smoking a cigarette just isnt nearly as enjoyable as vaping. Its been just over a year since I've had a cigarette. I can taste better, I can breathe better, my clothes and car dont smell like smoke, and I don't have to go outside in the cold to smoke anymore.
Vaping is a safe, and novel way to enjoy nicotine, without second-hand (or first hand, for that matter) smoke.
Unfortunately theres a lot more FUD out there than real facts. Most is based on myth, and lack of understanding.
-Jason