With Regulation (EU) 2024/1328, the European Union is significantly tightening the restrictions on the cyclic siloxanes D4, D5 and D6. Comprehensive prohibitions on placing these substances and numerous mixtures on the market now apply. Companies should therefore assess at an early stage whether products, formulations or supply chains are affected.
The new regulation is particularly relevant for companies in the chemical and pharmaceutical industries, but manufacturers of cosmetics, personal care products, detergents and cleaning agents, plastics, silicone products and technical formulations should also carefully evaluate the new requirements.
Regulation (EU) 2024/1328 of 16 May 2024 amends entry 70 of Annex XVII to the REACH Regulation (EC) No 1907/2006. The following substances are affected:
D4 – Octamethylcyclotetrasiloxane
Cyclic siloxanes are used primarily as starting materials for silicone polymers. They also perform numerous technical functions, for example as:
They are found, among other things, in:
Why are D4, D5 and D6 restricted?
The European Union considers these substances particularly critical because of their environmental and long-term effects.
The assessment is as follows:
With the restriction, the European Commission aims to significantly reduce long-term emissions of these substances into the environment.
The central ban on placing substances on the market since 6 June 2026
The most important change concerns the placing of these substances on the market. Since 6 June 2026, D4, D5 and D6 may no longer be placed on the market if the concentration of the respective substance is 0.1% by weight or more.
This applies to:
The often-cited statement about the “ban on placing on the market” is therefore fundamentally correct and corresponds to the provision in the amended version of entry 70 of Annex XVII to the REACH Regulation.
Important: The restriction relates to placing substances on the market within the EU. Depending on the application, additional REACH obligations or sector-specific regulations may also be relevant.
Key deadlines at a glance
6 June 2024: Effective Date of the Regulation
6 June 2026: Start of the general ban on placing D4, D5 and D6 on the market at ≥ 0.1% w/w
6 June 2027: Start of certain later applicable restrictions for specific uses in accordance with the transitional provisions of entry 70
6 June 2029: Further transitional period for certain special applications ends
31 May 2031: End of the longest transitional period for certain medical devices and other expressly listed applications
The Regulation contains numerous exemptions and staggered transitional periods so as not to jeopardize technical or safety-relevant uses in the short term. These include, among others:
Intermediates
Certain uses as isolated intermediates are not affected, subject to the conditions of the REACH Regulation.
Industrial manufacturing processes
For the following industrial applications, transitional periods apply when the substances are used under controlled conditions: — as a monomer in the manufacture of silicone polymer; — as an intermediate in the manufacture of other silicone substances; — as a monomer in polymerization; — for the formulation or (re-)packaging of mixtures; — in the manufacture of articles; — in non-metallic surface treatment.
Medical applications
For certain medical devices and their manufacture, extended transitional periods apply until 31 May 2031.
Medicinal products
The REACH regulation contains exemptions for substances that fall within the scope of European pharmaceutical legislation. Companies in the pharmaceutical industry should nonetheless check whether intermediates, excipients or technical formulations outside these exemptions are affected.
Other expressly specified special applications
The amended entry 70 contains further specific exemptions, for example for certain laboratory, research or technically justified uses. Whether an exemption actually applies must be examined in each case on the basis of the specific wording of the entry.
Which sectors are particularly affected?
Chemical industry
For chemical companies there is often an immediate need for action. The following may be affected:
In addition to their own product portfolios, suppliers and customers should also be involved at an early stage.
Pharmaceutical industry
Pharmaceutical companies are partially protected by specific exemptions. Nevertheless, they should check
The supply chain may also be affected by the new prohibitions on placing on the market.
Cosmetics and personal care industry
This sector is particularly strongly affected. D4 and D5 had already been restricted for certain cosmetic uses. The new Regulation now significantly expands the requirements and extends them to D6.
Plastics and silicone industry
Also manufacturers of silicone elastomers, sealants, engineering plastics and silicone-based specialty products should review their formulations and raw material lists. As D4, D5 and D6 are important starting materials for silicone polymers, sourcing and product development may be affected.
By the time the new restrictions apply, companies should in particular:
Systematic chemicals management helps to identify regulatory risks at an early stage and avoid supply bottlenecks.
Conclusion
With Regulation (EU) 2024/1328, the European Union significantly tightens the requirements for handling the cyclic siloxanes D4, D5 and D6. The general ban on placing on the market, which entered into force on 6 June 2026, poses new challenges in particular for companies in the chemical, pharmaceutical, cosmetics as well as plastics and silicone industries. Those who already assess which products, formulations or supply chains are affected will create planning certainty and be able to implement necessary adjustments in good time.