• The Dangerous Goods list classifies dangerous goods that have similar properties into in segregation groups, indicating which ones may be transported together and which ones may not.

Dangerous goods with similar chemical properties are grouped together in segregation groups. Some substances, mixtures, solutions, or preparations falling within a segregation group are not listed in the International Maritime Dangerous Goods (IMDG) Code by name, but are shipped under n.o.s. entries. Although n.o.s. entries are not listed in the segregation groups, the consignor must decide whether including them under the segregation group is appropriate and, if so, must note that fact in the transport document.

The segregation groups in the IMDG Code do not cover substances that fall outside the classification criteria of the Code. Some non-hazardous substances have similar chemical properties as substances listed in the segregation groups. If the consignor or the person responsible for packing the goods into a cargo transport unit has knowledge of the chemical properties of those non-dangerous goods, they may voluntarily use the segregation provisions of a related segregation group.

The segregation groups are identified in the IMDG Code Section 3.1.4, and include:

• Acids,
• Ammonium compounds,
• Bromates,
• Chlorates,
• Chlorites,
• Cyanides,
• Heavy metals and their salts,
• Hypochlorites,
• Lead and its compounds,
• Liquid halogenated hydrocarbons,
• Mercury and mercury compounds,
• Nitrites and their mixtures,
• Perchlorates,
• Permanganates,
• Powdered metals,
• Peroxides,
• Azides, and
• Alkalis.