Hazardous materials are defined by the U.S. Department of Transportation in accordance with the Federal Hazardous Material Law. A substance or material may be designated as hazardous if the transportation of the material in a particular amount and form poses an unreasonable risk to health and safety or property. Hazardous material may include: an explosive, radioactive material; etiologic agent; flammable or combustible liquid or solid; poison; oxidizing or corrosive material; and compressed gas.