If you look closely at Dow's published literature that member aubergine posted, you'll see some interesting details.
Dow's Statements
• PG USP/EP is the product grade approved for food, pharmaceutical,
beverage, animal feed (except cat food) and cosmetic applications.
A list of non-supported or non-recommended applications for these Dow products
has been developed, primarily based on:
Dow policy on specific applications, such as use in tobacco
or medical
devices.
That would rule out a ton of pharmaceuticals, which you can see is a contradiction of their own terms since their PG is classified for use in pharmaceuticals.
But here's their key statement....."Dow will not sample these products in specific applications, will not knowingly sell these products for use in specific applications...."
So a vendor or supplier could just create a shell company (d.b.a.) and by-pass all of it.