Dangerous Goods

The transport of dangerous goods by sea prompted great challenges to the maritime industry — how to ensure the safety of life at sea and prevent pollution from ships. Under the auspices of the United Nations, the specialized agency International Maritime Organization (IMO) has worked out two conventions to address these issues: the International Convention for the Safety of the Life at Sea (SOLAS) and the International Convention for the Prevention of pollution from Ships (MARPOL).


To supplement the principles described in the SOLAS and MARPOL conventions, the IMO developed the International Maritime Dangerous Goods (IMDG) Code, detailing a uniform set of technical specifications to enable dangerous goods to be transported by sea. It contains provisions on handling, packing, labeling, marking, stowage, and segregation of dangerous goods, including recommendations on emergency response. The code is now a legal requirement for transport.
The IMDG Code has spread to all shipping-related industries. It is used by other worldwide organizations, such as the International Air Transport Association (IATA), and is the basis for several transnational conventions, such as the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR).

In the IMDG Code, a United Nations committee of experts has structured the classification of dangerous goods for all modes of transport (sea, air, rail, road and inland waterways) into nine classes and various subclasses, according to the chemical characteristics producing the risk. There are specific placards for each hazard class, that shippers should affix outside the container walls.

Each of the nine classes identifies dangerous goods by two pieces of information:

  • A four-digit number known as the UN Number, which is preceded by the letters UN.
  • The corresponding Proper Shipping Name (PSN).

For example, acetone is identified in the IMDG Code in class 3, by UN Number UN 1090 and the PSN Acetone.


Class 1 - Explosives

Explosives are materials that can conflagrate or detonate quickly because of chemical reactions. They can cause catastrophic damage through force and/or of producing otherwise hazardous amounts of heat, light, sound, smoke or gas.

Examples: ammunition, fireworks, flares, fuse, detonators, primers, igniters, rockets, air bag inflators, toy caps.

1.1 - Explosives with a mass explosion hazard

Subclass 1.1 - Explosives with a mass explosion hazard

Consists of explosives that have a mass explosion hazard. A mass explosion is one that may affect the entire load instantaneously.
Examples: nitroglycerine, dynamite.

1.2 - Explosives with a severe projection hazard

Subclass 1.2 - Explosives with a severe projection hazard

Consists of explosives that have a projection hazard but not a mass explosion hazard.

1.3 - Explosives with a fire

Subclass 1.3 - Explosives with a fire

Consists of explosives that 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 - Minor fire or projection hazard

Subclass 1.4 - Minor fire or projection hazard

Consists of explosives that present a minor explosion hazard. The explosive effects confine to the package and no projection of fragments of appreciable size or range is to be expected. An external fire must not cause virtually instantaneous explosion of almost the entire contents of the package.

1.5 – Very insensitive blasting agents

Subclass 1.5 – Very insensitive blasting agents

Consists of very insensitive explosives with a mass explosion hazard (explosion similar to 1.1). This division comprises substances that have a mass explosion hazard but are so insensitive that there is a weak probability of initiation or of transition from burning to detonation under normal conditions of transport.

1.6 - Extremely insensitive explosives

Subclass 1.6 - Extremely insensitive explosives

Consists of extremely insensitive articles that do not have a mass explosive hazard. This division is comprised of articles which contain only extremely insensitive detonating substances and which show a negligible probability of accidental initiation or propagation.

Class 2 - Gases

Some gases can pose serious hazards due to their flammability, potential as asphyxiants, ability to oxidize and/or their toxicity or corrosiveness to humans. This class includes gases in a compressed state, liquefied, dissolved, refrigerated liquefied gases, and mixtures of one or more gases with these characteristics.

2.1 - Flammable gases

Subclass 2.1 - Flammable gases

Gases that ignite on contact with an ignition source, such as acetylene and hydrogen. Flammable gas means any material that is ignitable at 101.3 kPa (14.7 psi) when in a mixture of 13% or less by volume with air, or has a flammable range at 101.3 kPa (14.7 psi) with air of at least 12% regardless of the lower limit.

Examples: disposable cigarette lighters and refills for gas lighters, acetylene (for oxy-acetylene welding and brazing), ethylene (for ripening fruit) and hydrogen (for university and industry use).

2.2 - Non-flammable, non-toxic gases

Subclass 2.2 - Non-flammable, non-toxic gases

Gases that are neither flammable nor poisonous. Includes the cryogenic gases/liquids (at temperatures below -100 °C) used for cryopreservation and rocket fuels. This division includes compressed gas, liquefied gas, pressurized cryogenic gas, compressed gas in solution, asphyxiant gas and oxidizing gas. A non-flammable, nonpoisonous compressed gas means any material which exerts in the packaging an absolute pressure of 280 kPa (40.6 psi) or greater at 20 °C (68 °F) and does not meet the definition of subclass 2.1 or 2.3.

Examples: carbon dioxide (found in soft drink dispensing machines), oxygen (for hospitals and oxy-acetylene welding), compressed air, freons (for refrigeration, air conditioning and polyurethane manufacture), compressed nitrogen and argon (for welding). Also, liquid oxygen and liquid nitrogen (for industrial applications).

2.3 - Toxic gases

Subclass 2.3 - Toxic gases

Gases liable to cause death or serious injury to human health if inhaled. Gas poisonous by inhalation means a material which is a gas at 20 °C or less and a pressure of 101.3 kPa (a material with a boiling point of 20 °C or less at 101.3kPa (14.7 psi)) which is known to be so toxic to humans as to pose a hazard to health during transport. In the absence of adequate data on human toxicity, it may be toxic to humans because when tested on laboratory animals it has an LC50 value of not more than 5000 ml/m3.

Examples: methyl bromide and ethylene oxide (for fumigation), chlorine (for commercial swimming pool water sanitation), ammonia (for industrial freezing works), fluorine, and hydrogen cyanide.

Some aerosols – fly sprays, room fresheners, aerosol deodorants – oven cleaners are assigned to subclasses 2.1 or 2.2 depending on their properties.

Class 3 - Flammable Liquids

Class 3 - Flammable Liquids

A flammable liquid means a liquid that may catch fire easily or any mixture having one or more components with any flash point, i.e. they give off a flammable vapor at temperatures lower than 60-65 °C. It is strongly advised for shipping liquids at or above its flash point in a bulk packaging.

There are three main groups of flammable liquids:

  • Low flash point - liquids with a flash point below -18 °C.
  • Intermediate flash point - liquids with a flash point from -18 °C up to +23 °C.
  • High flash point - liquids with a flash point from +23 °C.

Examples: oil, petrol, diesel, mineral turpentine, kerosene, methylated spirits, enamel paints, car lacquers, polyurethane varnish, two-pot polyurethanes and their solvents, most varnishes and some dry-cleaning fluids, methanol, methyl ethyl ketone (acetone) and polyester resin kits.

Class 4 - Flammable Solids or Substances

4.1 - Flammable solids

Subclass 4.1 - Flammable solids

Solid substances that are easily ignited. Self-reactive materials, which are thermally unstable and that can undergo a strongly exothermic decomposition even without the presence of air. Readily combustible solids that can cause a fire through friction and show a burning rate faster than 2.2 mm (0.087 inches) per second, or metal powders that can be ignited and react over the whole length of a sample in 10 minutes or less.

Examples: matches, fire lighters, sulphur powder, nitrocellulose, magnesium, synthetic camphor, naphthalene (moth balls).

4.2 - Spontaneously combustible substances

Subclass 4.2 - Spontaneously combustible solids

Solid substances that ignite in a spontaneous way. Spontaneously combustible material is a pyrophoric material, which is a liquid or solid that can ignite within five minutes after coming in contact with air or a self-heating material that when in contact with air and without an energy supply is liable to self-heat.

Examples: white or yellow phosphorus, aluminium alkyls, copra and unstabilised fish meal.

4.3 - Dangerous when wet

Subclass 4.3 - Dangerous when wet

Solid or liquid substances that emit a flammable gas when wet. They are made of a material that when it makes contact with water it is liable to become spontaneously flammable or give off flammable or toxic gas at a rate greater than 1 L per kilogram of the material per hour.

Examples: calcium, sodium, potassium metals and calcium carbide (used to produce acetylene gas).

Class 5 - Oxidizing substances and organic peroxides


5.1 - Oxidizing agents

Subclass 5.1 - Oxidizing agents

Oxidizing agent means a material that may, generally by yielding oxygen, cause or enhance the combustion of other materials.

Examples: calcium hypochlorite, some home bleaches, ammonium nitrate, hydrogen peroxide, potassium permanganate. Products used for stripping printed circuit board.

5.2 - Organic peroxides

Subclass 5.2 - Organic peroxides

Organic peroxides are any organic compounds containing oxygen in the bivalent structure and which may be considered a derivative of hydrogen peroxides, where one or more of the hydrogen atoms have been replaced by organic radicals.

Examples: benzoyl peroxides, cumene hydroperoxide, hardeners used in manufacturing industries.

Class 6 - Toxic and infectious

Any materials, other than a gas, known to be so poisonous to humans that they present a health hazard during transportation.

6.1 - Toxic

Subclass 6.1 - Toxic

Poisonous substances that are able to cause death or serious hazard to humans health.

Examples: pesticides, mercuric chloride, methylene chloride, potassium cyanide, sodium cyanide (for metal treatment). Several metal degreasers are poisons, such as chromium salts in electroplating and copper chrome arsenate mixtures for timber preservatives.

6.2 - Biohazards

Subclass 6.2 - Biohazards

These materials are infectious because they contain pathogens, or, at least, are presumed to do so. Pathogens are microorganisms (including bacteria, viruses, rickettsiae, parasites, fungi) and other agents such as prions, which can cause disease in humans or animals.

Examples: used intravenous needles, blood samples from people with infectious and/or notifiable diseases, septic tank effluent wastes, cultures containing pathogen(s) which may cause infection.

Class 7 - Radioactive Substances

Class 7 - Radioactive substances

Radioactive substances comprise substances or a combination of substances that emit ionizing radiation, such as uranium and plutonium.

Examples: Materials used in industrial thickness measuring devices, for the sterilization of medical products and as a treatment for cancer.

Class 8 - Corrosive Substances

Class 8 - Corrosive substances

A corrosive material means a liquid or solid that causes full thickness destruction of human skin at the site of contact within a specified period of time. For example, a liquid that has a severe corrosion rate on steel is also a corrosive material.

8.1 - Acids

Examples: hydrochloric acid, sulfuric acid.

8.2 - Alkalis

Examples: sodium hydroxide (caustic soda), potassium hydroxide (caustic potash).
Many dairy sanitizers and industrial cleaners are corrosive and belong to this class.

Class 9 - Miscellaneous

Class 9 - Miscellaneous

A material which presents a hazard during transport but which does not meet the definition of any other hazard class. This class includes any material that has an anesthetic, noxious or other similar property that could cause extreme annoyance or discomfort to a crew member so as to prevent the correct performance of assigned duties, or material for an elevated temperature material, a hazardous substance, a hazardous waste, or a marine pollutant.

Class 9 should not be regarded as presenting a lower risk than Classes 1 to 8.

Examples: blue, brown and white asbestos (cancer hazard), PCBs (environmental and health hazards), some ammonium nitrate fertilizers and environmentally hazardous substances, lithium ion batteries, car batteries, dry ice, self-inflating life rafts.



Some substances should not be stowed together in the same container. They should follow separation requirements, a practice known as segregation. When sending dangerous goods, shippers should follow the segregation rules described in the IMDG Code. These should apply not only to the multimodal transport but also to the storage and handling stages.

The segregation table below outlines basic incompatibilities between different classes and subclasses, whether they can be shipped or not inside the same container.


X – YES, they can load in the same container. Please check the IMDG Code for further provisions.

1 – NO, they cannot load in the same container. Keep “away from”.

2 – NO, they cannot load in the same container. Keep “separated from”.

3 – NO, they cannot load in the same container. Keep “separated by a complete compartment or hold from”.

4 – NO, they cannot load in the same container. Keep “separated longitudinally by an intervening complete compartment or hold from”.

How to use the segregation table?

Let us suppose a shipper wants to send Class 5.2 organic peroxides with Class 3 flammable liquids in the same container. At the intersection of the respective column and row of each class, there is number 2, which means the two materials should not be carried in the same container and should be placed separated from each other. Only substances of classes marked with intersection X may co-load within the same container.

There are many subsidiary risks that require different and multiple safety provisions. You should always consult the dangerous goods list (DGL) in the IMDG Code for specific details.

The information above is for general reference only.
Please ask your carrier for guidance before you arrange for a shipment with dangerous goods.