The Secretary of the Department of Transportation receives the authority to regulate the transportation of hazardous materials from the Hazardous Materials Transportation Act (HMTA), as amended and codified in 49 U.S.C. 5101 et seq. The Secretary is authorized to issue regulations to implement the requirements of 49 U.S.C. The Pipeline and Hazardous Materials Safety Administration (PHMSA) (formerly the Research and Special Provisions Administration (RSPA)) was delegated the responsibility to write the hazardous materials regulations, which are contained in 49 CFR Parts 100-180.

The applicability of the hazardous materials regulations was extended to all intrastate shipments of hazardous materials by highway effective October 1, 1998, as published in the final rule, Docket HM-200 dated January 8, 1997. This final rule also provided exceptions for “materials of trade”, “agricultural operations” and certain non-specification packaging used in commerce.

The hazardous materials regulations are applicable to the transportation of hazardous materials in commerce and their offering to:

• Interstate, intrastate, and foreign carriers by rail car, aircraft, motor vehicle and vessel.
• The representation that a hazardous material is present in a package, container, rail car, aircraft, motor vehicle or vessel.
• The manufacture, fabrication, marking, maintenance, reconditioning, repairing or testing of a package or container which is represented, marked, certified or sold for use in the transportation of hazardous materials (49 CFR 171.1(a))

“Persons” who offer for transportation, or transport in foreign, interstate or intrastate commerce: (a) any highway route controlled quantity of a Class 7 (radioactive) material; (b) more than 25 kg (55 lbs.) of a Division 1.1, 1.2, or 1.3 (explosive) material in a motor vehicle, rail car or freight container; (c) more than 1 L per package of a material extremely poisonous by inhalation; (d) a hazardous material in a bulk packaging having a capacity of 3,500 gals. for liquids or gases, or more than 468 cubic feet for solids; (e) a shipment in other than bulk packaging of 5,000 lbs. gross weight or more of one class of hazardous material for which the transport vehicle requires placarding; (f) any quantity of materials requiring placarding.