Classification of substances and mixtures

Classification

Manufacturers, importers and downstream users must classify substances or mixtures in accordance with Title II of the CLP Regulation before placing them on the market. 

Classification is the way to determine whether a substance or mixture is hazardous to human health and/or the environment and/or poses a physical hazard. The classification is based on the hazard of the substance/mixture but not on the risk. To classify a substance/mixture, information on the hazards of the substance/mixture must be compared with the classification criteria set out in Annex I to the CLP Regulation and a decision must be made as to which hazard class (physical, health or environmental hazards) and category (degree of hazard) is most appropriate for the substance/mixture.

The classification of a substance or mixture reflects the type and seriousness of the hazard posed by that substance or mixture, i.e. the potential harm to humans and the environment. The CLP Regulation sets out criteria for deciding whether the classification of a substance or mixture is appropriate. In order to make a self-classification, the obligor must gather all available information and assess its suitability and reliability. Thus, classification must include an assessment of all physico-chemical, toxicological and ecotoxicological properties which may cause hazards to man or the environment during normal handling of substances or mixtures. 

Substances shall be classified using one or both of the following methods before being placed on the market:

• harmonised classification;
• a self-classification based on the rules referred to in Title II of the CLP Regulation, using the relevant criteria.

According to the CLP Regulation, a substance must be self-classified when it is not subject to harmonised classification and has hazardous properties. If a substance is already subject to harmonised classification (CLP Annex VI contains a classification entry), harmonised hazard classification is mandatory, taking into account the hazard classes and differentiations included in the entry. Hazard classes and differentiations not covered by the entry shall be self-assessed and classified.

Chemical mixtures must always be classified independently before being placed on the market, as they are not subject to harmonised classification and labelling.  Chemical mixtures shall be classified on the basis of data relating to the mixture as a whole. If data are not available for the mixture as a whole, then the mixture may be classified by applying the bridging principles when the mixture is classified on the basis of data for similar mixtures or the mixture shall be classified taking into account information on the hazardous properties of the components of the mixture. This assessment shall take into account the harmonised classification, if any, of each substance in the mixture.

Guidance to operators on the classification of substances/mixtures

There are five main steps to classify substances/mixtures:

1. Gather all available information to help determine the classification of each substance or mixture.
2. Check the information to make sure it is relevant and reliable so that it can be used for classification.
3. Evaluate the information in accordance with the classification criteria set out in Annex I to the CLP Regulation.
4. Decide on the appropriate classification.
5. If necessary, review the classification.

When should the classification be reviewed?

The classification may need to be reviewed for a number of reasons, such as:

• Table 3 of Part 3 of Annex VI to the CLP Regulation replaces the harmonised classification of substances.
• your supplier changes the classification in the safety data sheet;
• a change in the concentration of one or more constituents results in a change in the composition of the mixture;
• new information on your substance becomes available, e.g. when REACH registration dossiers are updated;
• changes to the classification criteria.

If required by REACH, manufacturers and importers should also classify substances that are not placed on the market. This provision applies to the classification of on-site isolated intermediates, transported intermediates and chemicals used in product and process orientated research and development (PPORD).

Manufacturers are also required to classify certain specific articles that meet the definition of ‘explosives’ in accordance with Chapter 2.1 of Annex I to the CLP Regulation.

Distributors (including retailers) and downstream users may take over the classification of a substance or mixture (e.g. from a safety data sheet) established by another actor in the supply chain, provided that they do not change the composition of the substance or mixture concerned.

The supplier must keep all information that he has used for the classification and labelling of substances and mixtures under the CLP Regulation for at least 10 years from the last date of placing on the market of the substance or mixture concerned. The competent authority of the Member State where the supplier is established (Environmental Protection Agency) or ECHA may require the supplier to provide such information. If the information required by the competent authority is included in the supplier’s notification to the classification and labelling inventory (or its registration dossier under REACH), such information can be accessed by ECHA and the competent authority should send a request to ECHA.

Hazard classes in the CLP Regulation

Since the entry into force of the CLP Regulation, the following hazard classes have been established for:

• Physical hazards - 16 classes.
• Hazards to human health - Class 10 + Class 1 (Endocrine disruptors in humans) -> Class 11.
• Environmental hazard class 2 (1 for substances hazardous to the ozone layer) + 3 (Environmental endocrine disruptors; persistent, bioaccumulative and toxic (PBT) or very persistent and very bioaccumulative (vPvB); Persistent, Mobile and Toxic (PMT) or Very Persistent and Very Mobile (vPvM)) -> Class 5.

Commission Delegated Regulation (EU) 2023/707, which amended the CLP Regulation and introduced 4 new hazard classes, entered into force on 20 April 2023.

Terminology

Since the entry into force of the CLP Regulation, the terminology for classification and labelling has changed:

Signal words ("Warning" and "Dangerous") should be used instead of hazard statements, hazard statements (e.g. H318: Serious eye damage) instead of risk phrases, precautionary phrases(e.g. P235: Store in a cool place) instead of safety phrases and use EUH phrases that provide additional hazard information (e.g. EUH 044: May explode if heated tightly closed).

ECHA guidance documents

• Guidanceon the Application of the CLP Criteria.
• Introductory guidance to the CLP Regulation.

Other sources of information

• European Commission’s Directorate-General for Environment (DG ENV) website with an overview and links to additional information.
• The website of the European Commission’s Directorate-General for Internal Market, Industry, Entrepreneurship and SMEs (DG GROW) provides an overview and links to additional information, including additional guidance.
• ECHA webpage on ‘Classification of substances and mixtures’.