[mistercow]

Honestly, I have doubts that there's much bad going to come of unregulated liquid. They're very simple solutions with few ingredients, and there isn't that much room to screw it up. If you bought ingredients from China, you might end up with VG and PG that weren't actually VG or PG, so there's one avenue. But the same thing happened with toothpaste years back, and toothpaste is regulated.

I'd actually be more concerned about the hardware than the liquid. It would be easy to cut costs by using unsafe materials for heating elements, solder, or the wicks. But even with all of that risk, you're going to have a hell of a time beating the harm of cigarettes.