DOT Definition of Hazardous Material:

A hazardous material is defined as any substance or material could adversely affect the safety of the public, handlers or carriers during transportation. All DOT hazardous materials are listed in the DOT’s Hazardous Material Table.

There are nine classes of hazardous materials:

Class Of HazardDescription
Hazard Class 1: Explosives1.1 mass explosion hazard
1.2 projectile hazard
1.3 minor blast/projectile/fire
1.4 minor blast
1.5 insensitive explosives
1.6 very insensitive explosives
Hazard Class 2: Compressed Gases2.1 flammable gases
2.2 non flammable compressed
2.3 poisonous
Hazard Class 3: Flammable LiquidsFlammable (flash point below 141°)
Combustible (flash point 141°-200°)
Hazard Class 4: Flammable Solids4.1 flammable solids
4.2 spontaneously combustible
4.3 dangerous when wet
Hazard Class 5: Oxidizers and Organic Peroxides5.1 Oxidizer
5.2 Organic Peroxide
Hazard Class 6: Toxic Materials6.1 Material that is poisonous
6.2 Infectious Agents
Hazard Class 7: Radioactive MaterialRadioactive I
Radioactive II
Radioactive III
Hazard Class 8: Corrosive MaterialDestruction of the human skin
Corrode steel at a rate of 0.25 inches per year
Hazard Class 9: MiscellaneousA material that presents a hazard during shipment but does not meet the definition of the other classes