Propylene Glycol is a colorless and has a slightly sweet taste. It also has very little odor. A commonly used chemical, it is mass produced and is key in polymer production.
When mixed with water, the freezing point of water is decreased. As such it is often used for aircraft de-icing. For the food industry the chemical is produced from propylene oxide. It is used as a preservative in food, as well as in tobacco products. Since it is non-toxic it is used in some food products such as ice cream, soda pop, liquid sweeteners and other items.
From a health view point it is not normally irritating to the skin, however it can irritate the eye. The irritation is generally minor and the eye will recover. There have been some studies that indicate that when inhaled, it can cause lung irritations. Because of these 2 factors this chemical is not normally used in areas where it will be inhaled or come into contact with eyes.