Thanks Derek, I had a deja vu with that link - I think I just looked there yesterday. The thing is, xtremevaping describes vg (and pg) like this: Our VG is sourced in the US, Is 99.7% Pure, USP,
Food Grade and Kosher.
After reading the diy-e-liquid Sticky:
http://www.e-cigarette-forum.com/forum/diy-e-liquid/52669-pg-vg-labeling-purity-please-read.html by Markarich159, Pharmacist, I've noticed, as it is explained in the thread, that even when USP is mentioned in a description it is not necessarily Pharmaceutical grade, but likely food grade.
The vendors I've looked at seem to be using the food grade standard, or do not say anything about the source or grade. Though it's [I think] the UK equivalent of U.S. Pharmaceutical grade, Decadent Vapours / Totally Wicked is the only one I've come across that makes a clear point of this standard.