The FDA (U.S. Food and Drug Administration) regulates packaging that meat and poultry is wrapped in. These materials may not contaminate the meat products with any adverse chemicals. Production plants must maintain a file of guarantees of FDA certification for all packaging used with the plant. This file may be reviewed at any time by FDA inspectors. Vacuum packaging removes the surrounding air from meats and provides a vacuum seal. This removes the majority of the oxygen present and prevents new oxygen from coming in contact. This lack of oxygen works to preserve the meat without the use of chemicals. Some vacuum sealing even infuses carbon dioxide or nitrogen gases to add as another barrier to decomposition and bacterial growth.