21 U.S.C. § 864
(a) It is unlawful for any person—
knowing, intending, or having reasonable cause to believe that such anhydrous ammonia will be used to manufacture a controlled substance in violation of this part.
(Pub. L. 91–513, title II, § 423, as added Pub. L. 106–310, div. B, title XXXVI, § 3653(a), , 114 Stat. 1240.)