1. 21 CFR 170.30.Eligibility for Classification as Generally Recognized as Safe (GRAS).https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=170.30(accessed on 2018).
2. 21 CFR 170.39.Threshold of Regulation for Substances Used in Food‐Contact Articles.https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfCFR/CFRSearch.cfm?fr=170.39(accessed on 2018).
3. 58 FR 52719.Food Additives: Threshold of Regulation for Substances Used in Food‐Contact Articles.https://www.gpo.gov/fdsys/pkg/FR‐1995‐07‐17/pdf/95‐17435.pdf(accessed on 2018).
4. 81 FR 54960.Substances Generally Recognized as Safe.https://www.gpo.gov/fdsys/granule/FR‐2016‐08‐17/2016‐19164(accessed on 2018).
5. 81 FR 83672.Indirect Food Additives: Paper and Paperboard Components.https://www.gpo.gov/fdsys/granule/FR‐2016‐11‐22/2016‐28116(accessed on 2018).