EU Enhances Restriction on the Use of Silicone D4, D5 and D6

“Silicone” is a generic term referring to a class of synthetic polymers that are based on a framework of alternating silicon and oxygen (siloxane) bonds with at least one organic group attached to the silicon atom via a direct carbon-silicon bond. They have an inorganic silicon-oxygen (Si-O) backbone and are defined as inorganic or hybrid substances.

Cyclosiloxanes D4, D5, D6 are silicone-based compounds that are very persistent and very bioaccumulative(vPvB). D4 is also suspected of damaging fertility.

Octamethylcyclotetrasiloxane(D4),Decamethylcyclopentasiloxane(D5)andDodecamethylcyclohexasiloxane (D6) are used to create a diverse range of silicone materials that provide unique, beneficial characteristics to a wide variety of applications and products across sectors, including construction, electronics, engineering, health care, cosmetics and personal care. These are essential raw materials for tailoring polysiloxane backbones resulting in high performing additives for the coating and inks industry. D4, D5 and D6 are most frequently used as chemical intermediates, meaning that the substances are employed in the manufacturing process but only present as low-level impurities in the end products. 

Based on the criteria used in REACH, D4 meets the criteria for Persistent, Bioaccumulative and Toxic (PBT) substances, and D5 and D6 meet the criteria for very Persistent, very Bioaccumulative (vPvB) substances. In addition, D5 and D6 are considered PBT when they contain more than 0.1% D4. This led to a nomination by EU Member States to the list of SVHCs. However we believe that the REACH criteria do not allow the full range of relevant scientific evidence to be considered and that not all relevant scientific evidence was thoroughly taken into account prior to decision making. 

By June 6, 2027, D4, D5 and D6 shall not be used in all cosmetic products with concentration of more than 0.1%

On May 16, 2024, the European Commission adopted Regulation (EU) 2024/1328 to amend REACH Regulation (Regulation (EC) 1907/2006), which introduces more restrictions on the use of D4, D5, and D6.

Octamethylcyclotetrasiloxane(D4),decamethylcyclopentasiloxane(D5)and dodecamethylcyclohexasiloxane (D6) are basic members of the broad family of silicone materials. They are primarily used as emollients, which help to moisturize and soften the skin, as well as improve the texture and spreadability of cosmetic products. 

Around 18000 tonnes of these siloxanes end up in our environment each year, for example through wastewater.Cosmetics are the main source of the releases.These releases result in an environmental stock of around 500 tonnes.

The use of these silicones in cosmetics has been a topic of regulatory scrutiny in some regions, notably in the EU. On January 10, 2018, the Commission adopted Commission Regulation (EU) 2018/35 restricting the placing on the market of D4 and D5 in wash-off cosmetic products.

On June 13, 2018, D4, D5 and D6 were identified by the Member State Committee of the European Chemicals Agency (ECHA) as substances of very high concern (SVHC) with very persistent and very bioaccumulative (vPvB) properties. D4 was identified as having persistent, bioaccumulative and toxic (PBT) properties. D5 and D6 were also identified as having PBT properties when they contain 0.1 % or more by weight of D4.

The European Union is restricting these siloxanes in consumer and professional products in the EU/EEA after 6 June 2026.

The restriction, developed by the European chemicals agency(ECHA), could prevent up to 90% of annual releases

The costs for companies are estimated to be up to 700 million euro over 20 years.

To address the risks to the environment posed by the use of D4, D5 and D6 when discharged into environmental compartments, the following restrictive measures are supplemented: 

• By June 6, 2026, D4, D5 and D6 shall not be placed on the market as a substance on its own or in mixtures in a concentration equal to or greater than 0.1%;
• By June 6, 2025, D4 and D6 shall not be used as a solvent for the dry cleaning of textiles, leather and fur;
• By June 6, 2027, D4, D5 and D6 shall not be used in leave-on cosmetics with concentration equal to or greater than 0.1%;
• By June 6, 2031, D4, D5 and D6 shall not be used in devices, medicinal products, and veterinary medicinal products;
• By June 6, 2034, D5 shall not be used as a solvent in the dry cleaning of textiles, leather and fur.