C12-15 pareth-12 (INCI name) is an emulsifier and surfactant commonly used in cosmetics formulations. It is a polyethylene glycol ether formed by combining synthetic C<sub>12</sub>âÂÂC<sub>15</sub> fatty alcohols with 12 moles of ethylene oxide.
According to the INCI, "the term Pareth applies to ethoxylated paraffinic alcohols containing both even- and odd-carbon chain length fractions."