Have been searching around for some information on PG as I've been primarily using PG in my DIY stash. Here's some interesting information. See where PG (Propylene Glycol) is used in the industry:

Propylene Glycol is used:

As a solvent in many pharmaceuticals, including oral, injectable and topical formulations. Notably, diazepam, which is insoluble in water, uses propylene glycol as its solvent in its clinical, injectable form.
As an emulsification agent in Angostura and orange bitters
As a moisturizer in medicines, cosmetics, food, toothpaste, shampoo, mouth wash, hair care and tobacco products
As a carrier in fragrance oils
As an ingredient in massage oils
In hand sanitizers, antibacterial lotions, and saline solutions
In smoke machines to make artificial smoke for use in fire-fighters’ training and theatrical productions.

As a solvent for food colours and flavourings
As an ingredient, along with wax and gelatine, in the production of paintballs.
As a moisture stabilizer (humectant) for snus (Swedish style snuff).
As a cooling agent for beer and wine glycol jacketed fermentation tanks
As a non-toxic antifreeze for winterizing drinking water systems, and in applications where the used antifreeze eventually will be drained into the soil, water, or a septic system.
As a less-toxic antifreeze in solar water heating systems
As a solvent used in mixing photographic chemicals, such as film developers In cryonics
As a working fluid in hydraulic presses
As a coolant in liquid cooling systems
To regulate humidity in a cigar humidor.
As the killing and preserving agent in pitfall traps, usually used to capture ground beetles
As an additive to pipe tobacco to prevent dehydration.
To treat livestock ketosis.
As the main ingredient in deodorant sticks.
To de-ice aircraft.
As an ingredient in UV or black light tattoo ink
As a lubricant in air conditioning compressors.
In the manufacture of lava lamps.