O-Cymen-5-OL is an antifungal preservative used in cosmetics and beauty products to prevent harmful bacteria from developing and to prolong the shelf-life of formulas. It is part of the Isopropyl Cresols family and is originally developed synthetically in the form of a crystal. O-Cymen-5-OL is also used as a cosmetic biocide, or ingredient that helps to cleanse the skin or to prevent odor by destroying or inhibiting the growth of microorganisms, according to research. O-Cymen-5-OL is approved by the FDA for use as a direct and indirect food additive and has been approved by the CIR for use in cosmetics up to .5% concentration. However, in the European Union, it is only approved for use up to .1%. Studies in Japan, some dating back to 1956, found O-Cymen-5-OL to be neurotoxic in animals and have led to heavier restrictions on its use in cosmetics there. O-Cymen-5-OL (Dekasol BL) is used in oral care, to fight periodontal disease.