Triacetin, also known as Glyceryl Triacetate, is reported to function as a cosmetic biocide, plasticizer, and solvent in cosmetic formulations, at concentrations ranging from 0.8% to 4.0%. It is a commonly used carrier for flavors and fragrances. Triacetin was affirmed as a generally recognized as safe (GRAS) human food ingredient by the Food and Drug Administration (FDA). Triacetin was not toxic to animals in acute oral or dermal exposures, nor was it toxic in short-term inhalation or parenteral studies, and subchronic feeding and inhalation studies. Triacetin was, at most, slightly irritating to guinea pig skin. However, in one study, it caused erythema, slight edema, alopecia, and desquamation, and did cause some irritation in rabbit eyes. Triacetin was not sensitizing in guinea pigs. Triacetin was not an irritant or a sensitizer in a clinical maximization study, and only very mild reactions were seen in a Duhring-chamber test using a 50% dilution. In humans, Triacetin reportedly has caused ocular irritation but no injury. Triacetin was not mutagenic. Although there were no available reproductive and developmental toxicity data, Triacetin was quickly metabolized to glycerol and acetic acid and these chemicals were not developmental toxins. Reports of 1,2-glyceryl diesters, which may be present in Triacetin, affecting cell growth and proliferation raised the possibility of hyperplasia and/or tumor promotion. The Cosmetic Ingredient Review (CIR) Expert Panel concluded, however, that the effects of 1,2-glyceryl diesters on cell growth and proliferation require longer ester chains on the glycerin backbone than are present when acetic acid is esterified with glycerin, as in Triacetin. On the basis of the available information, the CIR Expert Panel concluded that Triacetin is safe as used in cosmetic formulations.