Diethyl phthalate (DEP) is a phthalate ester, namely the diethyl ester of phthalic acid. It is a clear substance that is liquid at room temperature and which does not occur in nature.
Diethyl phthalate is produced by the reaction of phthalic anhydride with ethanol in the presence of a catalytic amount of concentrated sulfuric acid.
Diethyl phthalate was reported as an ingredient in 67 cosmetic formulations at concentrations ranging from ≤0.1 % to 25-50%. These cosmetics included bath preparations (oils, tablets, and salts), eye shadows, toilet waters, perfumes and other fragrance preparations, hair sprays, wave sets, nail polish and enamel removers, nail extenders, nail polish, bath soaps, detergents, aftershave lotions, and skin care preparations