I've said it before, but I'm too lazy to find my own post right now. Glycerin is not necessarily VEGETABLE glycerin. However, if it says USP then it is at such a purity level that the source is irrelevant (unless you are opposed to consuming animal products for moral/ethical reasons.)
AFAIK any USP grade glycerin is as safe as any other and they are all the same product. If you want to know what organism the glycerin was extracted from, you will have to contact the (new favorite word->) Manufactory.
AFAIK any USP grade glycerin is as safe as any other and they are all the same product. If you want to know what organism the glycerin was extracted from, you will have to contact the (new favorite word->) Manufactory.