For the purposes of this chapter, the term "hazardous materials" means substances or materials in a quantity and form that may pose an unreasonable risk to health, safety, or property when transported in commerce and includes explosives, radioactive materials, etiological agents, flammable liquids or solids, combustible liquids or solids, poisons, oxidizing or corrosive materials, or compressed gases.
D.C. Code § 8-1402