food prior to January 1, 1958, a grandfather clause allows experience based on common use in food to be used in asserting an ingredient is safe under the conditions of their intended use. The FDA can also explicitly withdraw the GRAS classification, as it did for trans fat in 2015. List of GRAS notices The list of GRAS notices is updated approximately each month by the FDA. Code of Federal Regulations The Code of Federal Regulations, revised , includes (CFR) title 21 170.30(b) that provides general recognition of safety through scientific procedures requires the same quantity and quality of scientific evidence needed to obtain approval of the substance as a food additive. and ordinarily is based upon published studies, which may be corroborated by unpublished studies and other data and information. Intended use The substance must be shown to be "generally recognized" as safe under the conditions of its intended use. For new proposals, the proponent of the exemption usually a food manufacturer or ingredient supplier wishing to highlight a food ingredient in its manufactured product has the burden of providing rigorous scientific evidence that use of the substance in an edible consumer product is safe. To establish GRAS, the proponent must show that there is a consensus of expert opinion that the substance is safe for its intended use. For existing GRAS items, new uses should not substantially exceed historical occurrence levels of the substance in the diet. Enforcement When use of a substance does not qualify for the GRAS exemption, it is subject to the premarket approval mandated by the Federal Food, Drug, and Cosmetic Act. In such circumstances, the FDA can take enforcement action to stop distribution of the food substance and foods containing it on the grounds that such foods are not deemed GRAS or contain an unlawfully added ingredient. An example of a non-GRAS ingredient requiring enforcement actions in the form of FDA warning letters to 15 companies in 2019 was cannabidiol, which, as of 2021, had not been established with sufficient scientific evidence of safety as a GRAS ingredient. See also Generally recognized as safe and effective Novel food Substantial equivalence References External links GRAS Notification Program, FDA, January 2020 Food additives Food safety Chemical safety Food and Drug Administration Food law