Preservative derived from mountain ash berries or manufactured synthetically. Sorbic acid is used in many products, including several foods and even in contact lens solutions. A study of contact sensitization to preservatives among 514 volunteers with eczema showed that sorbic acid caused a reaction in only 0.6% of participants. In contrast, many other preservatives had much higher rates of negative reactions, upwards of 13.6% (Source: Ceska a Slovenska Farmacie, May 2004, pages 151–156).