R 325.5054 Thorium used in certain articles.

Rule 54. A person is exempt from this part to the extent that he or she receives, possesses, uses, or transfers any quantity of thorium contained in the following: (a) Incandescent gas mantles. (b) Vacuum tubes. (c) Welding rods. (d) Electric lamps for illuminating purposes if each lamp does not contain more than 50 milligrams of thorium. (e) Germicidal lamps, sunlamps, and lamps for outdoor or industrial lighting if each lamp does not contain more than 2 grams of thorium. (f) Rare earth metals and compounds, mixtures, and products containing not more than 0.25% by weight thorium, uranium, or any combination of these.