You are using the present tense. I have no idea what's approved today.
Glycerol (glycerin) is used as a humectant and antifungal. Polypropylene glycol is used similarly. You can drink polypropylene glycol. Diethylene glycol ingestion can be fatal.
Bob
EDIT: If you'd like to squander a portion of your life looking at all the bizarre stuff that's gone into tobacco over the years, you can search the "Truth Tobacco Industry Documents" on the UCSF website:
https://www.industrydocumentslibrary.ucsf.edu/tobacco/ There are hundreds of thousands of pages of "insider" info. There is even a section of tobacco industry videos.