answer:I don’t think there’s been any kind of long term study on the stuff, yet. Not that I’ve ever seen. The FDA, currently, isn’t regulating them. I’ve been using them since December ‘12 and haven’t suffered in any way as yet. I’ve given up smoking, though. I only use the eCig for something to do. I’m down to 0 nicotine in the juice. If you get nicotine, though, then you get the same health problems associated with that (blood pressure, etc) just without the smoke.