- D4 (Octamethylcyclotetrasiloxane) D4

- D5 (Decamethylcyclopentasiloxane) D5

- D6 (Dodecamethylcyclohexasiloxane) D6

Restriction of D4 and D5 in Personal Care Products:

Octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) have been added to REACH annex XVII restricted substances list (entry 70) by COMMISSION REGULATION (EU) 2018/35 on 10 Jan 2018. D4 and D5 shall not be placed on the market in wash-off cosmetic products in a concentration equal to or greater than 0.1 % by weight of either substance, after 31 January 2020.

Substance Conditions of Restriction
OctamethylcyclotetrasiloxaneEC number: 209-136-7,

CAS number: 556-67-2


EC number: 208-746-9, 

CAS number: 541-02-6

1. Shall not be placed on the market in wash-off cosmetic products in a concentration equal to or greater than 0.1 % by weight of either substance, after 31 January 2020.2. For the purposes of this entry, “wash-off cosmetic products” means cosmetic products as defined in Article 2(1)(a) of Regulation (EC) No 1223/2009 that, under normal conditions of use, are washed off with water after application.’

Why Are D4 and D5 Restricted?

D4 and D5 are cyclosiloxanes mainly used as monomers for silicone polymer production. They also have a direct use in personal care products. D4 has been identified as a persistent, bioaccumulative and toxic (PBT) and very persistent very bioaccumulative (vPvB) substance. D5 has been identified as a vPvB substance.

Due to concerns that D4 and D5 may have the potential to accumulate in the environment and cause effects that are unpredictable and irreversible in the long-term, ECHA’s Risk Assessment (RAC) and Socio Economic Assessment (SEAC) Committees agreed with the UK’s proposal to restrict D4 and D5 in wash-off personal care products in June 2016 since they may go down the drain and enter lakes, rivers, and oceans. 

Restricted Use of D4 and D5 in Other Products?

So far D4 and D5 are not restricted in other products. ECHA is working on an additional proposal to restrict D4 and D5 in leave on personal care products and other consumer/professional products (e.g. dry cleaning, waxes and polishes, washing and cleaning products). The proposal will be submitted for approval in April 2018. Industry has expressed strong objections to this additional restriction.

In March 2018, ECHA has also proposed to add D4 and D5 to SVHC list.


  • Committee for Risk Assessment (RAC) Approves Proposal to Restrict D4 and D5 Use in 
  • Wash-off Cosmetics
  • Intentions of the Restriction of D4 and D5 in Other Products
  • Slicones Europe - Additional REACH restrictions for D4 and D5 are premature and unjustified – June 2017

What are silicones?

Silicones are specialty products that are used in hundreds of applications where their special performance is needed. They are used as adhesives, they insulate, and they have excellent mechanical/optical/thermal resistance among many other properties. They are used, for example, in medical technologies, renewable energy and energy saving solutions, as well as digital technologies, construction and transportation.

What are D4, D5 and D6 and where are they used?

Octamethylcyclotetrasiloxane (D4), Decamethylcyclopentasiloxane (D5) and Dodecamethylcyclohexasiloxane (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.

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.

What does SVHC mean?

SVHC stands for “Substance of Very High Concern”.

Who made the SVHC decision?

The decision to identify D4, D5, D6 as SVHC was made by the ECHA Member States Committee (MSC), which is composed of experts nominated by EU Member States and ECHA.

The MSC members were asked to review the technical dossiers submitted by Germany for D4 and D5, and by ECHA for D6, as well as the comments received during the public consultation.

The mandate of these experts is to assess and confirm the scientific basis underpinning the SVHC proposals, and not to assess the potential impact.

Why were D4, D5 and D6 listed as SVHC?

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 the criteria do not allow the full range of relevant scientific evidence to be considered.

Post time: Jun-29-2020