Harmonised Classification of Substances

What Is Classification?

Classification determines how hazardous a chemical substance or mixture is. Without it, you cannot prepare a safety data sheet (SDS) or correctly identify the hazardous properties of a product.

Every substance or mixture must be classified before it is placed on the market.

The rules are laid down in Regulation (EC) No 1272/2008 (CLP) of the European Parliament and of the Council. It establishes a harmonised system for the classification, labelling and packaging of chemical substances and mixtures. It also defines the obligations of manufacturers, importers and downstream users.

What Is Harmonised Classification?

Harmonised classification is a legally binding classification listed in Annex VI to the CLP Regulation. You must therefore adopt all information from the Regulation without any modifications.

Where necessary, you may add additional hazard classes and the corresponding H statements, thereby making the classification more stringent. However, you must not alter or remove any information laid down in the Regulation. The only exception is minimum classifications. These are identified by an asterisk next to the H statement (most commonly for acute toxicity). Such hazard classifications may be changed to a more stringent classification, for example from Acute Tox. 4 H302 to Acute Tox. 3 H301.

Information Included in a Harmonised Classification

1. Index number in the format XXX-XXX-XX-X. For example, nicotine has the index number 614-001-00-4.

2. Chemical name of the substance in all official EU languages.

3. CAS number (where available), assigned by the Chemical Abstracts Service.

   Did you know? The last digit of a CAS number is a check digit. Take all digits except the last one, multiply each digit by its position counting from right to left (1, 2, 3, …), add the products together, and divide the total by 10. The remainder is the check digit.

4. EC number – EINECS, ELINCS or NLP (where available), which is the official identifier of the substance within the European Union. The EC number consists of seven digits in the format XXX-XXX-X.

5. Classification includes H statements in accordance with Annex III. For some H statements, the three-digit code is supplemented by letters used to provide further distinction.
   For example, H360D – May damage the unborn child.

6. Labelling includes hazard pictograms, a signal word, H statements and EUH statements.

7. Specific concentration limits (SCLs), acute toxicity estimates (ATEs), and M-factors supplement the general rules used to calculate the classification.

8. Notes clarify how the harmonised classification should be applied or interpreted in specific cases. For example, Note C states that certain organic substances may be placed on the market either as a specific isomer or as a mixture of several isomers. The supplier must therefore indicate on the label whether the substance is a specific isomer or a mixture of isomers.

Where Can I Find Harmonised Classifications?

Harmonised classifications are listed in Annex VI to the CLP Regulation. This Annex is regularly updated through ATP Regulations (Adaptation to Technical and Scientific Progress). Based on new scientific evidence and technical developments, these Regulations introduce new classifications, amend existing ones, or remove them.

Individual Regulations can be found, for example, on EUR-Lex, where European Union legislation is published.

Harmonised classifications are also available in the ECHA CHEM online database, maintained by the European Chemicals Agency (ECHA). It contains both substances with harmonised classifications and substances classified by manufacturers or importers.

When Does a Harmonised Classification Apply?

Each new Regulation specifies the date from which the harmonised classification becomes mandatory (date of application). In most cases, it also provides for a transitional period. During this period, the classification is not yet mandatory, but you may already start using it (date of entry into force). This gives suppliers sufficient time to update their documentation in line with the new requirements.

The date from which the new classifications may be used is always stated in the Regulation before the table of harmonised classifications of substances. The exact dates can also be found on EUR-Lex in the Document information section.

For example, Commission Regulation (EU) 2025/1222 (23rd ATP):

• was published in the Official Journal of the European Union on 20 June 2025,
• entered into force on 10 July 2025 – from this date, the new classifications may be used,
• from 1 February 2027, the harmonised classification laid down in this Regulation must be applied.

How Can I Verify a Harmonised Classification?

If you need to verify the harmonised classification of a substance, search for it in the ECHA CHEM database. We recommend searching by CAS number, EC number or index number.

You can identify whether a substance has a harmonised classification by its assigned index number. Another indication is the ATP number displayed in the Classification & Labeling – Harmonized classifications section of the ECHA CHEM database.

In SBLCore, you can find all substances with harmonised classifications, including the relevant ATP number. The system also notifies you whether the classification is up to date or whether a newer classification under another ATP Regulation already applies. This makes it easy to verify that you are working with the latest information.

What Should I Do If the Classification Changes?

Check the Regulation's date of entry into force and the date of application of the new classification. These dates determine how much time you have to update your documentation.

If you use SBLCore, the software will notify you of the change both in the safety data sheet and in the substance database.

If the classification of a harmonised substance changes, you must update both the safety data sheet and the label no later than the date of application of the new classification.

For example:

• the Regulation was published on 1 May 2024,
• the new classification must be applied from 1 May 2025.

The transitional period is therefore one year. During this period, you must update the safety data sheet, the label, and make any other necessary changes.

Disclaimer: This article is for informational purposes only and does not replace the applicable legislation.

Recommended Sources

• Regulation (EC) No 1272/2008 – consolidated version of the CLP Regulation
• Commission Regulation (EU) 2025/1222 – 23rd ATP
• ECHA CHEM database
• EUR-Lex