New Restrictions on Silicones D4, D5, and D6 in the European Union

In 2018, we will remember that the silicones Octamethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5) were restricted in rinse-off cosmetic products.

The reason? Their high environmental impact. Specifically, D4 is a PBT substance (persistent, bioaccumulative, and toxic) and vPvB (very persistent and very bioaccumulative). D5 is also vPvB.

At that time, products that remained on the skin, hair, or mucous membranes, i.e., leave-on products, were not considered an environmental risk.

With the limitation of D4 and D5, D6 (Dodecamethylcyclohexasiloxane) came into play as a good option to replace them due to its similarity. Given this circumstance, it was proposed to evaluate its potential risk since it is also a vPvB substance. Its use was hanging by a thread!

So what has finally happened with the regulation of these chemical substances in the European Union?

The chronological decline of silicones D4, D5, and D6

As we have seen, the regulation (EU) 2018/35 officially marks the beginning of the decline of these silicones, primarily due to their environmental impact.

At that time, the concentration of D4 and D5 in rinse-off products was limited to 0.1%. It was considered that this concentration would ensure they would not be used, as to be effective, they needed to be at much higher concentrations.

Thus, the race to replace them began, with a maximum deadline set for January 31, 2020. After this date, cosmetic products that were rinsed off with water and did not comply with this restriction could no longer be marketed.

The following year, in 2019, the European Chemicals Agency (ECHA) demonstrated the need to address the environmental risks posed by the use of D4, D5, and D6 in cosmetic products that end up being released into aquatic and atmospheric environments.

The ECHA Member State Committee identified them as substances of very high concern (SVHC) due to their PBT and vPvB properties. This increased concern about their potential to cause unpredictable, long-term, and difficult-to-reverse effects on the environment.

Considering the use of these silicones in leave-on products and their ease of dispersal with the use of such cosmetics, it was observed that they did constitute an important source of release. For this reason, new measures were needed to allow for better control.

Additionally, in 2019, D4 was added to Annex II of the Cosmetics Regulation (EC) 1223/2009 for being considered a CMR substance. Therefore, its use in cosmetics was completely prohibited (Regulation (EU) 2019/831).

Finally, on May 16, 2024, Regulation (EU) 2024/1328 comes into force. To control and further limit the use of these silicones, entry 70 of Annex XVII of the REACH Regulation 1907/2006 is modified again.

Keep reading to see how these changes affect the cosmetic industry.

What happens now with cosmetics? What are the restrictions, prohibitions, and transition periods?

As we have seen, there have been several important milestones that have modified the use of these silicones, even beyond cosmetics.

In the following table, you will find all the summarized information on the changes brought about by the entry into force of Regulation (EU) 2024/1328.

Additionally, it is important to emphasize that these regulatory changes are mandatory and subject to the indicated transition periods. So, the countdown to replace them has begun!

 Regulated Substance (INCI)

Chemical name CAS Regulatory Status Observations Prohibition /Restriction Date

Cyclotetrasiloxane (D4)








In 2019, it was added to Annex II of Regulation 1223/2009 Since 2019 for Cosmetic Productos

Cyclopentasiloxane (D5)






Restricted in mixtures, to a maximum concentration of 0.1% by weight of the substance  

 Rinse off products: 31/01/2020

Leave on products: 06/06/2027


Cyclohexasiloxane (D6)






In mixtures, to a maximum concentration of 0.1% by weight of the substance  

Productos rinse off: 06/06/2026

Productos leave on: 06/06/2027

How can we help you from Sigillum?

We can advise you on the interpretation and compliance with the requirements derived from Regulation (EU) 2024/1328, ensuring that your cosmetic products meet all current norms and regulations, and promoting a safe and responsible cosmetics industry.

So, don’t hesitate any longer, and contact us here!