Classification of Chemicals According to UN-GHS and EU-CLP: A Review of Physical Hazard Classes and Their Intricate Interfaces to Transport and Former EU Legislation

Cordula Wilrich, Elisabeth Brandes, Heike Michael-Schulz, Volkmar Schröder, Silke Schwarz


The Globally Harmonized System of Classification and Labelling of Chemicals (UN-GHS) is being implemented in more and more countries all over the world; the EU has done so with the CLP-Regulation (EU-CLP). Compared to the undeniably important questions on health and environmental hazards, the classification of physical hazards of chemicals often has not been in the focus, although their implementation can be challenging and there are traps and pitfalls to be avoided. The following overview of the classification systematics for physical hazards aims at a principle understanding without detailing all criteria or test methods. Similarities and differences between the classification systems of the UN-GHS and EU-CLP, the transport of dangerous goods and the former EU system are reviewed with regard to the physical hazard classes. Available physical hazard classifications for the transport of dangerous goods and according to the former EU system can be used as available information when classifying according to the GHS. However, the interfaces of these classification systems and their limitations have to be understood well when concluding on GHS/CLP classifications. This applies not only to industry when applying CLP but especially to legislators when adapting legislation that in one way or another refers to the classification of chemicals.


GHS, CLP-Regulation, Classification of chemicals, Physical hazards

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Globally Harmonized System of Classification and Labelling of Chemicals (GHS): .

Information about the world-wide GHS Implementation: .

REGULATION (EC) No 1272/2008 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006.

Substances Directive (67/548/EEC) and Preparations Directive (1999/45/EC), both repealed on June 1st, 2015. In the following, these are referred to as the former EU system.

UN Recommendations on the Transport of Dangerous Goods ‒ Model Regulations: .

UN Manual of Tests and Criteria: .

The test methods for physico-chemical properties as contained in the Test Methods Regulation (COUNCIL REGULATION (EC) No 440/2008) were referred to in the former EU system according to Substances and Preparations Directives. These are the so-called 'A-test methods'.

ISO 10156:2010 'Gases and gas mixtures -- Determination of fire potential and oxidizing ability for the selection of cylinder valve outlets'.

This new category for pyrophoric gases is foreseen to be introduced with the 12th ATP to CLP.

Test O.3 was introduced with the sixth revised edition of the GHS. Reference to Test O.3 is not yet implemented in CLP.

J. Gmehling, P. Rasmussen, 'Flash Points of Flammable Liquid Mixtures Using UNIFAC', 21:2 Industrial & Engineering Chemistry Fundamentals (1982), 186.

E. Brandes, M. Mitu, D. Pawel, 'The lower explosion point ‒ A good measure for explosion prevention: Experiment and calculation for pure compounds and some mixtures', 20:4-6 Journal of Loss Prevention in the Process Industries (2007), 536.

Section of Annex VI to the Substances Directive.

Informal document 12 of the 23rd session of the UN Sub-Committee of Experts on the GHS: .




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