21 CFR §184.1137

1. (a)Ammonium carbonate ((NH4)2CO3, CAS Reg. No. 8000-73-5) is a mixture of ammonium bicarbonate (NH4HCO3) and ammonium carbamate (NH2COONH4). It is prepared by the sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard, white or translucent mass.
2. (b)The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), p. 19, which is incorporated by reference. Copies are available from the National Academy Press, 2101 Constitution Ave. NW., Washington, DC 20418, or available for inspection at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
3. (c)In accordance with § 184.1(b)(1), the ingredient is used in food with no limitation other than current good manufacturing practice. The affirmation of this ingredient as generally recognized as safe (GRAS) as a direct human food ingredient is based upon the following current good manufacturing practice conditions of use:
   1. (1)The ingredient is used as a leavening agent as defined in § 170.3(o)(17) of this chapter and a pH control agent as defined in § 170.3(o)(23) of this chapter.
   2. (2)The ingredient is used in food at levels not to exceed current good manufacturing practice.
4. (d)Prior sanctions for this ingredient different from the uses established in this section do not exist or have been waived.