Your lack of knowledge is showing. The liquid used is not oil. It is comprised of vegetable glycerin (a safe food additive), propylene glycol (another safe food additive), and flavorings often created the same way essential oils are distilled. One could argue that the flavoring agents are the problem, but for the most part, most of the ingredients in the liquid are water soluble.

Many vapers make their own liquid, myself included, and carefully source all ingredients. I can control every aspect of the final product, so tell me how that is corruptible?