23rd ATP to CLP published: major reclassification of nitrous oxide and more

The 23rd ATP was published on 20th June, 2025, introducing new harmonised classifications for 22 substances and updated harmonised classifications for a further 10 substances. The new classifications must be adopted by 1st February 2027.

What’s new?

The new classifications include the controversial reclassification of nitrous oxide as a Category 1B reproductive toxicant which is expected to have significant impacts on the food and cosmetics industries amongst others. The ATP also includes classifications for several other substances that are used in cosmetics such as fragrances and preservatives.

For further information, see Delegated regulation - EU - 2025/1222 - EN - EUR-Lex.

EU vs GB: diverging paths on substance classification

These classifications will only apply to products placed on the market in the EU/EEA including Northern Ireland.

Great Britain has its own process for determining mandatory classifications for substances. Some of the substances in the 23rd ATP are included in the next proposed update to the GB MCL list, albeit not always with the same classification as adopted in the EU, for example:

• Nitrous oxide is proposed as a Category 2 reproductive toxicant in GB, a less severe classification than the EU's Category 1B classification.

The latest proposed update to the GB MCL which includes new or updated classifications for 30 substances was notified to the WTO earlier this year and is scheduled for adoption at the end of Q3 2025. More information can be found at G/TBT/N/GBR/101.

What this means for you

These changes will require businesses to act by: 

• Updating classification and labelling of affected substances and mixtures
• Updating Safety Data Sheets (SDS)
• Modifying REACH registrations
• Updating Poison Centre Notifications (PCNs)

Companies working across the EU and GB markets must stay alert to divergent classifications, which may create regulatory complexity and impact market access.

Need help navigating these changes?

Our team of regulatory experts can guide you through what the 23rd ATP means for your business, and help ensure you stay compliant, whether you're operating in the EU, GB, or both.

Contact us today