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1  ADR works in such a way that classification is the precursor for everything that follows.  Once a substance or article has been properly classified, table A (ADR 3.2.1) allows every other requirement to be ascertained by working logically through the columns.


2  The rules for classification are in ADR at part 2. Dangerous substances (and this includes articles) are very widely defined, but some, for example most medicines and cosmetics, do not have the hazardous properties that would bring them within scope of the requirements, and those that do are usually carried in very small receptacles, allowing at least partial exemption from the requirements (either limited quantities or limited loads - see Main Exemptions)

3  Consignors have a duty to identify the hazards of the goods they intend to transport. There are nine classes, some with divisions, as follows.

UN Class Dangerous Goods Division(s) Classification
1 Explosives 1.1 - 1.6 Explosive
2.1 Flammable gas
2.2 Non-flammable, non-toxic gas
2.3 Toxic gas
3 Flammable liquid   Flammable liquid
4 Flammable solids 4.1 Flammable solid
4.2 Spontaneously combustible substance
4.3 Substance which in contact with water emits flammable gas
5 Oxidising substances 5.1 Oxidising substance
5.2 Organic peroxide
6 Toxic substances 6.1 Toxic substance
6.2 Infectious substance
7 Radioactive material   Radioactive material
8 Corrosive substances   Corrosive substance
9 Miscellaneous dangerous goods   Miscellaneous dangerous goods

4 Part 2 of ADR works through the categories in logical sequence.  It sets out descriptions and criteria in some detail.  The consignor must assign a "proper shipping name" and UN Number to the substance.

5 All relevant  hazards have to be determined (ADR There is a hierarchy of classification (ADR and there are rules about choosing the most appropriate entry and hence UN number (ADR 3.1.2).

6 Many substances and generic groups (e.g. paints) have already been classified, so in many cases a consignor may only need to find his substance in the "dangerous goods list", which is in part 3 of ADR. The lists are by UN Number (Table A) and alphabetical (Table B) . Both lists are at the end of Volume 1 of ADR.

7 Many preparations (i.e. mixtures of substances) will not be found in table A of ADR. In those cases the rules for classification need to be followed.

8 An important change was made in ADR 2011 in paragraph The effect of this is that dangerous goods should be classified and named according to the properties of the predominant substance, and in general the presence of impurities is not relevant. There are some specific exceptions which are set out in

9 Once a UN number and proper shipping name have been assigned, table A allows all the relevant parts of ADR to be accessed. Some substances with the same name will have different degrees of danger (for example flash point). This is reflected in the “packing group” (PG), which is found in column 4 of table A. The head of column 4 in turn directs you to the relevant part of ADR (in this case Where a substance has been classified from “first principles”, its PG will be determined by its properties (for example ADR shows how flammable liquids are assigned a PG)

10 Some substances are not assigned a PG (notably gases and explosives), but they do have a transport category, the relevance of which will be discussed elsewhere (Main Exemptions) in relation to limited load exemptions. In certain special circumstances it may not be practicable to classify the goods fully before carriage, for example when sending samples for analysis. In such cases it is acceptable to "over-classify" the goods on the basis of the information which is already available (ADR 2.1.4).

11 Proper shipping names may also be qualified by the addition of the terms such as 'SOLUTION'; 'LIQUID'; 'SOLID'; 'MOLTEN', 'STABILIZED'. Details at ADR to

12 ADR has changed in respect of classification for environmental hazards. There are links to the “supply” classifications implemented in GB by the CHIP regulations and to the GHS system of classification. See ADR at and This means that all dangerous goods, not just those directly assigned UN 3077 (solids) or UN 3082 (liquids), meeting the relevant criteria will be regarded as environmentally hazardous substances and required to show the “dead fish and tree” mark. The requirements for the mark mirror the provisions for labels and placards (ADR and 5.3.6).


13 With the exception of clinical waste, wastes are classified in the same way as other substances. The rules at ADR mean that where generic or “NOS” names are chosen, the substance or substances giving rise to the hazards may have to be named. See Special Provision 274 where it appears in column 6 of Table A. The word “WASTE” should qualify other descriptions where applicable (ADR, and should appear before the “Proper Shipping Name”.

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Updated 2020-06-04