Hazard Classification

Clachemicals_safety_trainingssification is used to determine if a chemical can cause harm to human health and the environment. It involves the identification and evaluation of hazard information (physical properties, human health and environment effects), and communication of those hazards on a label and in a safety data sheet. All substances and mixtures manufactured or imported into the EU and placed on the EU market must be classified

Classification may be triggered through the CLP Regulation or the REACH Regulation processes:

a)      Under the CLP Regulation: any manufacturer, importer or downstream user of a substance or mixture, placed on the EU market, must classify the substance or mixture. Classification is regardless of tonnage.

b)      Under the REACH Regulation: any manufacturer or importer of a substance, on its own or in a mixture, subject to REACH registration (at > 1 tonne per annum)  must classify the substance. Classification is regardless of whether the substance on its own or in a mixture, is placed on the market.



There are five basic steps to self-classify a substance or a mixture:

1.       Collection of available information

2.       Evaluation of the adequacy and reliability of the information

3.       Review of the information against the classification criteria

4.       Decision on classification

5.       Review of classification

Classifying Substances

Evaluation of hazard information may indicate that the substance meets the criteria for classification for a particular hazard, in accordance with Annex I of CLP. Classification must then be assigned to communicate the hazard. Classification includes assigning a hazard class and category or differentiation, a signal word, hazard statements, hazard pictograms and precautionary statements.

Some substances have an agreed upon or ‘harmonised’ classification for some or all hazards, these are listed in Annex VI of CLP and must be applied.

Specific concentration limits (SCLs) and generic concentration limits (GCLs) are limits assigned to a substance indicating a threshold at or above which the presence of that substance in another substance or in a mixture, leads to the classification of the substance or mixture as hazardous. The substance may be a constituent of a mono- or a multi- constituent substance or mixture, or may be present as an identified impurity, additive or individual constituent. An SCL is based on adequate and reliable scientific data indicating that the hazard of concern is still evident below the GCL. Some substances have a harmonised SCL, these are listed in Annex VI of CLP and any harmonised SCL must be applied.

Classifying Mixtures

If the evaluation of the hazard information on the mixture as a whole is available, the mixture is classified for hazards in the same way as substances are classified using the criteria of Annex I to CLP. Physical hazards must normally be based on the mixture itself. Where hazard information is not available on the mixture as a whole, the mixture may be classified based on sufficient information of the substances in the mixture for human health and environmental hazards. Classification based on substances in mixtures is based on the application of the “bridging principles”, which make use of data on similar tested mixtures and information on individual components. Expert judgement should be applied to ensure that existing data on similar mixtures can be exploited for as many mixtures as possible.

Where substances classified for a human health or environmental hazards are present in the mixture, any harmonised classifications for the substances present in the mixture, including any specific concentration limits and M-factors that are provided in Annex VI to CLP must be applied.


Harmonised Classification

Where classification of physical, human health and/or environmental hazards have been harmonised under Annex VI of the CLP Regulation, including any specific concentration limits and M-factors, the harmonised classification must be applied.

The classifications of substances of special concern are included in the EU harmonised list in Annex VI to CLP. The classifications in Annex VI are legally binding and are available to download or search online here.  


Classification Guidance

ECHA: Harmonised Classification of Substances

ECHA: Mixture Classification

ECHA: The Guidance on the Application of the CLP Criteria

BAUA:  step-by-step guidance on classification


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