Commonly referred to as PG and sometimes listed as 'propane-1,2-diol' in research articles, is an odourless, colourless and slightly sweet organic binding agent. Over 70 years of research has been conducted on PG proving that it is safe for human inhalation over long periods of time and the reason PG is used as the base compound for asthma inhalers. Propylene Glycol and Vegetable Gycerine have been classified as GRAS (Generally Regarded As Safe) and do not represent a cancer hazard. PG attracts moisture which can lead to the drying of the throat and causes it to feel sore. This usually passes after a couple of days and drinking more fluid may help relieve the symptoms. If you are allergic to PG we recommend that you seek the advice of your GP before purchasing or using the VIP E-Cig