Tea Tree Oil: Classification and Key Differences between the EU and the UK

In recent years, the classification of tea tree essential oil (INCI: Melaleuca alternifolia Leaf Oil, CAS 68647-73-4) has begun to diverge between the regulatory framework of the European Chemicals Agency (ECHA) in the European Union and that of the Health and Safety Executive (HSE) in Great Britain.

This regulatory evolution has a direct impact on manufacturers, importers, and distributors of cosmetics that use this natural ingredient in their formulations.

Table of contents

1. What has really changed?

2. A regulatory scenario that separates

3. A practical perspective for businesses

Tea Tree Oil: Classification and Key Differences between the EU and the UK

What has really changed?

• In November 2023, the ECHA —through its Risk Assessment Committee (RAC)— adopted the opinion to classify tea tree oil as a Reproductive Toxicity Category 2 (Repr. 2) substance under the EU CLP Regulation.

• However, in August 2025, the HSE published its technical proposal under Article 37 of the British CLP, establishing a future mandatory classification (GB MCL) for this essential oil.

• Although the British authority recognizes risks such as skin irritation, dermal sensitization, acute toxicity and aquatic environmental impact, it does not currently propose a classification for reproductive toxicity.

A regulatory scenario that separates

Since Brexit, the EU and the UK have been pursuing parallel regulatory paths. This means that the same substance—such as Tea Tree Oil —can be subject to different classification criteria depending on the market.

For the cosmetics industry, this translates into very specific challenges:

1. Different labels and SDS: Safety data sheets and hazard warnings may vary between the UK and the EU.

2. Review of concentrations and formulations: applicable usage limits and warnings may differ depending on the new European classification.

3. Complex export flows: the border between the UK, Northern Ireland and the EU will require stricter controls to prevent non-conformities.

A practical perspective for businesses

More than a to-do list, this situation calls for a strategic review. If your company uses Melaleuca alternifolia Leaf Oil in cosmetic products, it is advisable to:

• Evaluate the concentrations and function of the ingredient within each formula, especially in products distributed in both the EU and the UK.

• Update the safety data sheets (SDS) and review the labeling texts according to the CLP criteria applicable in each region.

• Coordinate with suppliers and importers to ensure that safety declarations and technical documentation are consistent between both markets.

• Maintain active regulatory monitoring, as the HSE may reconsider the reproductive toxicity classification in future revisions of Article 37A.

The divergence in the classification of Tea Tree Oil is a clear example of how the post-Brexit framework is beginning to generate substantial differences in the management of cosmetic ingredients.

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