New Restriction on Substances D4, D5, and D6: Impact on Medical Devices
Regulation (EU) 2024/1328 of 16 May 2024 amends Annex XVII of the REACH Regulation by introducing significant restrictions on the use of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) due to their very persistent and very bioaccumulative (vPvB) properties, and in some cases, persistent, bioaccumulative, and toxic (PBT) properties. These restrictions have specific implications for several sectors, including medical devices, cosmetics, and pharmaceuticals.
This regulation will apply as of 6 June 2026 with general prohibitions for substances D4, D5, and D6, which can no longer be placed on the market:
- As isolated substances.
- As constituents of other substances.
- In mixtures at concentrations equal to or greater than 0.1% by weight.
EQUITOX has identified the key elements of these restrictions for medical devices. For this sector, the regulation provides for extended transitional periods and specific exemptions:
- Extended transitional period until 6 June 2031
For medical devices (as defined in Regulation (EU) 2017/745) and in vitro diagnostic medical devices (as defined in Regulation (EU) 2017/746), the deadline is extended to 6 June 2031. This delay is justified by the need to identify substitute substances, carry out qualification tests to validate the safety and performance of alternatives, and complete the necessary regulatory updates (certifications, CE marking).
- Specific exemptions
Certain uses in medical devices are exempt from the restrictions under specific conditions:
- Devices for scars, wounds, and stomas: Substances D5 and D6 can continue to be used without specific concentration limits for devices intended for scar treatment and care, wound prevention, and stoma care.
- Dental impression devices: Mixtures containing ≤ 0.3% D5 or ≤ 1% D6 can be used for dental impressions.
- Other medical devices (not mentioned above): Tolerated concentrations are ≤ 0.2% for D4, D5, or D6 for applications other than dental.
- Limit values for mixtures containing residual D4, D5, and D6
For certain devices where silicone residues are present, limit values are set to ensure regulated use:
| Application | Maximum Allowed Concentration |
| Adhesion, sealing, molding | ≤ 1% (D4, D5, or D6) |
| Protective coatings (marine) | ≤ 0.5% (D4) / ≤ 0.3% (D5 or D6) |
| 3D printing | ≤ 1% (D4, D5, or D6) |
| Rapid prototyping and molding | ≤ 1% (D5) / ≤ 3% (D6) |
The implications for medical device manufacturers require immediate actions to identify whether D4, D5, or D6 substances are present in their products or processes. If so, their concentrations must be quantified to ensure compliance with the defined thresholds. These actions will enable planning for compliant alternatives by 2031 to avoid any regulatory disruption.
These restrictions may have direct consequences on certification processes. Any formulation change will require an update of the technical documentation and CE certifications (according to Regulation (EU) 2017/745).
Regulation (EU) 2024/1328 encourages stakeholders to seize opportunities for innovation by investing in the development of environmentally friendly alternatives and positioning compliant products as a competitive advantage.
The new restriction on substances D4, D5, and D6 can be seen as a step forward in limiting the environmental impact of chemical products. However, it imposes significant challenges on medical device manufacturers, particularly in terms of reformulation, qualification, and certification. The transitional periods and exemptions provide time to adapt, but it is essential to start preparing now to ensure long-term compliance.
EQUITOX experts are here to support you in ensuring compliance and turning these constraints into opportunities: contact@equitox.eu