The European Union has taken a decisive step in regulating cyclic silicones with the adoption of Commission Regulation (EU) 2024/1328, amending the REACH framework. This update significantly reshapes the future use of D5 (Decamethylcyclopentasiloxane) and D6 (Dodecamethylcyclohexasiloxane) in cosmetic products, marking a transition that both manufacturers and consumers should understand.
What are D5 and D6, and what are they used for?
However, regulatory attention has not focused on their cosmetic performance, but rather on their environmental profile.
According to assessments by the European Chemicals Agency (ECHA), D5 and D6 meet the criteria for vPvB substances—very persistent and very bioaccumulative. This means they:
- Degrade very slowly in the environment
- Accumulate in living organisms and ecosystems
The concern is not primarily human toxicity under normal use, but the long-term environmental impact, especially due to widespread release through rinse-off products.
What does Regulation (EU) 2024/1328 change?
Regulation (EU) 2024/1328 introduces a harmonized restriction on cyclic silicones under the REACH Regulation (EC) No 1907/2006.
Key provisions:
- Concentration limit:
D5 and D6 cannot be placed on the market in substances or mixtures at concentrations equal to or greater than 0.1% by weight. - Timeline:
- 6 June 2026: General restriction applies to placing on the market
- 6 June 2027: Extension to all cosmetic products, including leave-on formulations
This is a crucial shift. While D5 was already restricted to 0.1% in rinse-off cosmetics since 2020, the new regulation:
- Extends the restriction to leave-on products
- Brings D6 under the same regulatory threshold
What does this mean in practice?
Although the regulation does not impose a total ban, the 0.1% threshold is far below typical functional use levels. As a result, the measure effectively leads to a phase-out of D5 and D6 in cosmetic formulations in the EU market.
Manufacturers will need to:
- Reformulate products well ahead of the 2027 deadline
- Validate alternative ingredients that deliver similar sensory benefits
- Ensure compliance across all product categories, not just rinse-off
A transition already underway
Many manufacturers have anticipated these changes and begun reformulating in advance. Alternatives such as non-volatile silicones (e.g., dimethicone), hydrocarbon-based emollients and ester oils are increasingly being used to replicate the sensory profile of cyclic silicones.
