I am using USP. I guess to be on safe side i should call the company that makes the walmart one called HUMCO...unless somebody already knows and can save me the work? As long as it doesn't come from an animal source I can continue using it for now.
It is sorta critical for me at this point.
You may never know for sure...

You could try calling Humco.
Look at #3: Composition/Ingredients: The exact composition is a trade secret.
http://www.humco.com/_pdfs/data-sheets/1031 Glycerin SDS.pdf
Here's a very old and very informative post by markarich159:
"They should make this a sticky because the newbies always ask this question. I'm a pharmacist in PA. I'm going to copy and paste a post I wrote in another subforum:
Go to the skin care aisle of most any pharmacy and you'll find a small(usually 6oz) bottle labled
Glycerine, USP(Some pharmacies don't carry outright , but will special order for you). The label may have it listed as CVS
Glycerine, USP or Rite Aid
Glycerine, USP or Humco
Glycerine, USP or Family Pharmacy
Glycerine, USP etc.. you get my point. Whatever it's labeled, it's
Glycerine, USP 99.5% anhydrous(meaning 0.5% water). It will cost anywhere from $3 to $6 for 6oz.(CHEAP) This is
vegetableglycerine, absolutely, positively, no doubt. How do I know this? I'm a pharmacist. All OTC
glycerine,USP is made by 1 single manufacturer, HUMCO. It is then contract packaged into the different pharmacy labeled bottles. I've personally called HUMCO and spoke with their QA(quality assurance) person. He assured me that HUMCO's
Glycerine is in fact
Vegetable source
Glycerine. The reason it's labeled
Glycerine and not
VegetableGlycerine is because #1 it is listed in the USP as
Glycerine, USP and therefore(in order to keep the USP certification) must be labeled as it's listed in the USP. #2 it would cause confusion as
Glycerine is
Glycerine(regardless of the source - chemically 1,2,3-propane triol also sometimes referred to as Glycerol), to add the moniker
VEGETABLE, makes it sound like it's two different and distinct products, it isn't. Also, USP grade
Glycerine is the purest you can get. Food Grade "
vegetableGlycerine" you get in health food store saying 99.9% is BS. Since they do not have to meet any standard(such as USP standards) they could say anything, they could say 10000% pure. If you get USP grade, you know you are getting exactly what is labeled(within allowable USP limits) and it is made to most stringent requirements available in the US. (i.e. USP stands for United States Pharmacopeia- drugs have meet higher standards then foods do). Kashrut(kosher) laws are Jewish religious dietary laws having to do with the preparation of food products and really have nothing to do with the labeled purity of the product. Also, Kashrut(kosher) laws are jurisdictional(handled differently in different places). In some cases a rabbi must come to the manufacturer and verify processes and equipment conform to kosher law and in some places it's enough that the manufacturer says or thinks he is conforming to the kosher laws. In any case USP and Kosher are 2 different things. There is no such listing in the USP for "Kosher
Glycerine". To the people who are feeling naseous using pharmacy bought
Glycerine, USP, it may be a placebo effect(thinking your not using the real VG) or you may have a sensitivity to
Glycerine(unlikely). But it is not because the Pharmacy bought
Glycerine,USP is inferior or NOT
VegetableGlycerine."