The European Union continues to strengthen its regulatory framework to reduce substances that are persistent and harmful to the environment. One of the latest developments concerns the cyclic silicones D5 (Cyclopentasiloxane) and D6 (Cyclohexasiloxane), widely used in cosmetic formulations.
New regulatory measures adopted under the REACH Regulation (EC) No 1907/2006 introduce stricter restrictions on the use of these substances in cosmetic and other consumer products.
These changes are part of the EU’s broader strategy to reduce substances that are persistent, bioaccumulative and potentially harmful to aquatic environments.
What are D5 and D6?
D5 and D6 belong to a group of substances known as cyclic volatile methylsiloxanes (cVMS).
In cosmetic products they are valued for their unique sensory and formulation properties, including:
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silky skin feel
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improved spreadability
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fast drying effect
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lightweight, non-greasy texture
Because of these characteristics, they are commonly found in:
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hair care products
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skin care products
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makeup and primers
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deodorants and sprays
Why are these substances being restricted?
Scientific assessments have shown that cyclic silicones such as D4, D5 and D6 can be very persistent in the environment and bioaccumulative (vPvB).
These substances:
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degrade very slowly in the environment
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can accumulate in living organisms
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have been detected in remote ecosystems such as the Arctic
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may pose risks to aquatic organisms
For these reasons, the European Chemicals Agency (ECHA) and the European Commission have introduced progressive regulatory restrictions.
Current regulatory status
Regulation of cyclic silicones has evolved over the past few years.
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D4 (Cyclotetrasiloxane)
Already banned in cosmetic products under EU Cosmetics Regulation (EC) No 1223/2009. -
D5 (Cyclopentasiloxane)
Since 2020, it has been restricted to maximum 0.1% in rinse-off cosmetic products.
What will change under the new restriction?
Under the new EU restriction introduced through REACH Annex XVII, additional limitations will apply.
From 6 June 2027:
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D5 and D6 will be restricted to a maximum concentration of 0.1% in all cosmetic products, including leave-on products.
This means that products such as:
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creams and lotions
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makeup products
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hair styling formulations
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deodorants
may need to be reformulated to comply with the new regulatory limits.
Impact on cosmetic manufacturers
The new restriction will have a significant impact on cosmetic formulation and product development.
Companies may need to:
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review their product formulations
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identify alternative ingredients
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update product safety assessments (CPSR)
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update Product Information Files (PIF)
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adapt supply chains and raw material specifications
Replacing D5 and D6 can be technically challenging, as few ingredients provide the same unique sensory profile and volatility.
What companies should do now
Although the restriction will apply in 2027, cosmetic companies are advised to begin preparing early.
Recommended actions include:
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reviewing existing formulations for D5 and D6 content
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assessing potential reformulation strategies
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consulting suppliers for alternative raw materials
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updating regulatory documentation where needed
Early preparation will help ensure a smooth transition and avoid disruptions in product availability on the EU market.
Conclusion
The upcoming restrictions on Cyclopentasiloxane (D5) and Cyclohexasiloxane (D6) represent another important step in the EU’s effort to reduce substances with significant environmental persistence.
While these changes present formulation challenges for the cosmetic industry, they also encourage innovation and the development of more environmentally sustainable cosmetic products.