PEG-8 is a synthetic polymer that binds moisture to the skin and is a solvent for other cosmetic ingredients that help them penetrate more effectively into the skin. Because polyethylene glycol (PEG) can penetrate the skin, it is also a “transport ingredient” that helps deliver other ingredients deeper into the skin. Polyethylene glycol used in cosmetics is purified and safe to use. Although once a concern, reputable cosmetic suppliers have long eliminated impurities from the finished ingredient, making PEGs safe for the skin.