Propylene glycol is one of the most widely used cosmetic ingredients, it is a humectant. It is a clear, colorless, viscous liquid, slightly bitter-tasting. It is the most common moisture-carrying vehicle, other than water itself, in cosmetics. Absorbs moisture, acts as a solvent and a wetting ingredient. Use as a carrier to dissolve your dry colorants and create liquid ones.
The Department of Health and Human Services (DHHS), the International Agency for Research on Cancer (IARC), and the EPA have not classified propylene glycol for carcinogenicity.
Propylene glycol is considered a safe and appropriate ingredient not just for cosmetic products, but also for ingested products like food and pharmaceuticals. It is on the US Food and Drug Administration's list of ingredients which are Generally Recognized As Safe (GRAS) and is recognized by the World Health Organization as safe for use.