Do you know the difference between an EC and list number?

1. What is an EC and list number?

2. What about new substances?

3. The impact of the EC and list number on SDS

4. Classification management of chemical substances

The EC and list number is an essential identifier in regulatory frameworks within the European market. Its function is to provide clear and standardized identification of substances, which is crucial in an industry that handles thousands of compounds daily—from cosmetic ingredients to complex industrial components.

While each substance can be described using its systematic chemical name, this is not practical in regulatory contexts. Therefore, more manageable numeric identifiers are used. The most internationally recognized is the CAS number, but within Europe, the EC number holds primary importance.

This number is linked to three historical inventories: EINECS, ELINCS, and NLP. From these stem the so-called list numbers, which also identify substances but with a more administrative or transitional purpose, depending on their regulatory status prior to REACH's entry into force.

Understanding the difference between them is important for the correct preparation of Safety Data Sheets (SDS) and compliance with REACH and CLP regulations.

What is an EC and list number?

The EC and list number is unique and composed of seven digits in the format XXX-XXX-X, assigned to a substance for identification in official records.
It can be considered its chemical ID. These numbers originate from historical inventories that the EU consolidated before REACH came into effect and are organized by numerical blocks based on their source:

• 2xx-xxx-x and 3xx-xxx-x: originate from the EINECS inventory (European Inventory of Existing Commercial Chemical Substances) which includes substances already on the market before September 18, 1981.

• 4xx-xxx-x: corresponds to the ELINCS inventory (European List of Notified Chemical Substances) for substances notified between 1981 and 2008 under the former Directive 67/548/EEC.

• 5xx-xxx-x: assigned to substances included in the NLP list (No-Longer Polymers), meaning substances that were previously considered polymers but no longer meet the current definition of a polymer under REACH.
  

As we can see, the EC and list number consists of officially and legally recognized numbers. They are published in the Official Journal of the European Union, making them valid legal documents for use within the REACH and CLP framework.

What about new substances?

When a substance is not listed in the official EU inventories—EINECS, ELINCS, or NLP—it cannot receive an official EC number. However, it still needs to be identified in order to comply with REACH procedures.

In such cases, ECHA assigns a list number, which serves as an administrative identifier. Unlike the EC number of chemical substances, a list number has no legal status for use in chemical regulation.

Administrative identifiers are typically generated through the REACH-IT system and follow the same format as EC numbers (XXX-XXX-X).

Below is a summary of the main ranges and their meanings:

• 6xx-xxx-x: automatically assigned to pre-registered substances with a CAS number but no EC number.

• 7xx-xxx-x: used when ECHA verifies the identity of the substance and confirms it as a unique entity.

• 8xx-xxx-x: logical continuation of the previous, applied when there is a CAS number but no match with any already registered substance.

• 9xx-xxx-x: intended for substances without a CAS number, such as complex mixtures, reaction products, or UVCB-type substances (Unknown or Variable composition, Complex reaction products or Biological materials).
  

As the available numeric list numbers are exhausted, ECHA plans to transition to an alphanumeric format. This new system will maintain the same length and structure (XXX-XXX-X) but incorporate letters to expand the allocation capacity.

Initially, the list number will begin with a letter in the first position, followed by digits. For example, we might see formats like A12-345-6.
Once all single-letter combinations are used (A to Z), two-letter combinations will follow (e.g., AB3-456-7), and so on, exponentially increasing the number of possible assignments.

The impact of the EC and list number on SDS

When preparing SDS, correctly identifying the substances in a mixture is essential to ensure traceability and comply with legal obligations in the European Union.
The EC and list number, if available, must be included in accordance with REACH. The CAS number and IUPAC name can also be included when known.

List numbers, however, have no legal status and are not mandatory in the SDS. They are not mentioned in Annex II of REACH as required identifiers, and their use is left to the discretion of the SDS author.

That said, list numbers can be useful in practice, especially when working with substances that have neither an EC number nor a CAS number.

Classification management of chemical substances

To properly manage the classification of chemical substances and prepare SDS, the best approach is to use a specialized tool.
A good example is eQgest, a software solution supported by a team of regulatory experts, equipped with features that facilitate the safe management of chemical products and ensure regulatory compliance.

Want to know how to streamline these processes in your company? One of our consultants can show you how eQgest helps you meet regulatory requirements. Contact us today!