Seriously... If you've studied chemistry, you know that a molecule by any particular name isn't different from another molecule of that same name, even if it was derived from a different source. Each part of the molecule's name describes a characteristic of the molecule. You can actually draw out a molecule and know what it looks like, just by looking at the name. I used to do it all the time with various household products, just for fun, when I was studying chemistry in college.

If something were different about it, even slight, it couldn't be called the same thing. Its prefix and/or suffix would change. Therefore, glycerol (glycerin) is glycerol is glycerol... Whether or not it came from an animal, vegetable, or synthetic source, it's still the exact same molecule and will react with your body in the same way. So as long as the lable says USP, indicating the product has met the purity standard of the United States Pharmacopeia, it's just glycerin. For example, you're not going to get any traces of animal oils if it comes from an animal source. I hope this info eases some minds. Just find the USP stamp of approval and you're good to
vape.