Actually USP means USP. It is a violation of federal law to label a non-USP product as USP with some serious bite.
Now, the funny thing is that a company can have USP but market it to uses that do not require USP.
So you can have USP that is marketed toward Food Use which is one notch below.
And you can have USP that is marketed toward Agricultural use which is a notch below Food grade.
And you can have USP that is marketed toward Machine use, which is below Agricultural grade.
Basically if a company meets USP requirements, they know for certain it is more pure than what is required for any grades below USP. Their business, marketing, and
insurance is geared toward a specific market, but the specifications for USP are well defined and have an independent organization they can contract with for the certification. Given the odd things one may have to go through when dealing with a government agency, and each individual agent of that agency, the consistency of an independent organization is easier to deal with as a business than than trying to gather the certs for a lower grade that is overseen by a government agency.
So if you want to make sure your product is good for external use, but want a consistent process to keep costs down, it makes
sense for the business to make USP product and label it for external use only. (Or whatever use the business was originated to serve.) Since the government helps to enforce USP standards, it's a huge win for USP. (This also applies to standards such as IBC, AASHTO, ANSI, NEC and others where the standard is from a private organization, but the government helps enforce the standards that the government has no hand in creating or developing.)
Thus us mixers encounter USP labeled PG and VG that is marketed toward food, cosmetics, animal, or machine use, but the key is the USP labeling since that is a standard of purity, packaging, packaging environment, and storage. Since the USP standard is a higher purity than food, agricultural, or machine, it is the USP that you need on the label. Feel free to overlook the marketing hype on the label.
