Too bad these statements are all incorrect.
Humco is NOT the only manufacturer of Glycerin in the US.
NOW and Heritage glycerin - from health food stores - are both USP.
Basically, from your experience, from things you've dealt with, maybe you are correct in many of your statements. But you obviously don't know everything.
I'm looking at a bottle of it right now, It's certainly NOT labeled as Glycerine, USP. It's labeled as all health food store Veg Glycerine's are, simply Vegetable Glycerine. Here's what it says on the website:
NOW® Vegetable Glycerine is a natural by-product of the cosmetic industry. It is derived from palm oil and is 100% pure
another website says:
NOW® Vegetable Glycerine is a USP grade, all-natural product derived from vegetable oil. BUT THEN:
NOW® Vegetable Glycerine is also food grade and is pure enough to be taken internally.
1st clue-NOTHING can be 100% pure, it's an unattainable percentage; not even chemical reagent grade (which is the highest grade possible) is 100% pure.
2nd clue- the labeling says one thing and the marketing says another. Actually the marketing is inconsisent, it says (on one website)that it's USP grade(which is impossible because USP grade is 99.5%) but then goes on to say later it's food grade(which is a lower grading).
Health Food Stores products are not required to follow the strict regulations that OTC and prescription products are, therefore, you see this type of labeling/marketing inconsistency all the time.
I know I don't know everything and you can follow your gut and buy whatever you like. If you like the NOW or Heritage products, buy them. I, however, knowing what labeling requirements are in place, would be leary of a product who's labeling and contents are, for the most part, unregulated, inconsistent, and patently false. But it's a free country, if you like it , buy it.
P.S. Heritage and NOW Veg Glycerines are NOT technically OTC products, they are health food products which are regulated totally differently then OTC products. So , yes, Humco, is the only producer, that I am aware, of that manufactures Glycerine, USP. They then contract package for all the other major Pharmacy labels.