21 C.F.R. § 355.20 – Packaging conditions.

(a) Package size limitation. Due to the toxicity associated with fluoride active ingredients, the following package size limitations are required for anticaries drug products:
1. (1) Dentifrices. Dentifrice (toothpastes and tooth powders) packages shall not contain more than 276 milligrams (mg) total fluorine per package.
2. (2) Preventive treatment gels and treatment rinses. Preventive treatment gel and treatment rinse packages shall not contain more than 120 mg total fluorine per package.
3. (3) Exception. Package size limitations do not apply to anticaries drug products marketed for professional office use only and labeled in accord with § 355.60.
(b) Tight container packaging. To minimize moisture contamination, all fluoride powdered dentifrices shall be packaged in a tight container as defined as a container that protects the contents from contamination by extraneous liquids, solids, or vapors, from loss of the article, and from efflorescence, deliquescence, or evaporation under the ordinary or customary conditions of handling, shipment, storage, and distribution, and is capable of tight reclosure.