49 C.F.R. § 173.140
For the purposes of this subchapter, miscellaneous hazardous material (Class 9) means a material which presents a hazard during transportation but which does not meet the definition of any other hazard class. This class includes:
[Amdt. 173-224, 57 FR 45463, Oct. 1, 1992, as amended by Amdt. 173-231, 57 FR 52939, Nov. 5, 1992; Amdt. 173-233, 58 FR 33305, June 16, 1993]