International Maritime Dangerous Goods (IMDG) Classes

Class 1 - Explosives

1.1 Substances and articles which have a mass explosion hazard.
1.2 Substances and articles which have a projection hazard but not a mass
1.3 Substances and articles which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard.
1.4 Substances and articles which present no significant hazard.
1.5 Very insensitive substances which have a mass explosion hazard.
1.6 Extremely insensitive articles which do not have a mass explosion.

Class 2 - Gases: Compressed, Liquefied or Dissolved under Pressure

2.1 Flammable gases
2.2 Non-Flammable gases
2.3 Toxic gases

Class 3 - Flammable Liquids

Class 4 - Flammable Solids or Substances

4.1 Flammable solids
4.2 Substances liable to spontaneous combustion
4.3 Substances which, in contact with water, emit flammable gases.

Class 5 - Oxidizing Substances (agents) and Organic Peroxides

5.1 Oxidizing substances (agents) by yielding oxygen increase the risk and intensity of fire
5.2 Organic peroxides - most will burn rapidly and are sensitive to impact or friction

Class 6 - Toxic and infectious Substances

6.1 Toxic substances
6.2 Infectious substances

Class 7 - Radioactive Substances

Class 8 - Corrosives

Class 9 - Miscellaneous dangerous substances and articles *

MHB - Materials hazardous only in bulk **

* - Marine pollutants which are not of an otherwise dangerous nature are listed in Class 9.
** - The regulations for materials hazardous only in bulk are not applicable to these materials when they are carried in closed freight containers, however, many precautions may have to be observed.