Propylene Glycol is used in a wide range of industries such as cosmetic, food, pharmaceutical, textile, air transport and automotive to name a few. However, it is important to note that Propylene glycol exists in several forms and concentrations. The USP (Pharmaceutical) grade is designed especially for use in topical and edible applications and has been granted GRAS (Generally Recognised As Safe) status by the FDA and has been deemed safe by the World Health Organisation. The Pharmaceutical Grade must not be confused with other grades used in applications such as engine coolant. Its principal use is as a humectant, a substance that retains water and thus prevents the drying out of substances to which it is added. It is also used as a solvent, particularly in the flavouring industry.