EU proposes restricting D4, D5, D6 as persistent organic pollutants in Stockholm Convention

03 Jul 2023 --- The EU is taking steps to limit cosmetic silicones octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) in the EU and potentially worldwide. Via a draft proposal, the EU Chemicals Agency (ECHA) suggests adding these silicones to the Stockholm Convention, a global treaty aiming to reduce the use of persistent organic pollutants (POP).

“The EU will consider stakeholders’ comments at relevant stages of the process under the Convention. These include preparing and reviewing a proposal for listing a chemical as a POP,” shares the ECHA.

The agency is open to receiving comments on the draft proposal to list D4, D5 and D6 in Annex B of the Stockholm Convention until August 10.

In a separate draft of the REACH Regulation, the EU Commission (EC) is proposing restricting D4, D5 and D6 on the market.

According to Japanese beauty brand Shiseido, D4, D5 and D6 are cyclosiloxanes, making them basic members of the broad family of silicone materials. “They are widely used because of the smooth and refreshing feeling they create.”

Evonik adds that these silicones are used across sectors, including construction, electronics, engineering, health care, cosmetics, personal care and household products.

Very concerning substances
The three silicones have been detected in human plasma, abdominal fat and breast milk, flags ECHA’s POP proposal.The Stockholm Convention aims to protect human health and the environment from persistent organic pollutants.

“Toxic effects on reproduction (D4), potential endocrine disruption (D4), carcinogenic effects in rats (uterine tumors attributed to D4 and D5), effects in lungs and nasal cavity (D4, D5 and D6) and liver enlargement (D4, D5 and D6) with histopathological findings (D4 and D6),” are also warned in the proposal.

ECHA proposed the restrictions on D4, D5 and D6 in January 2019 and the EC is now presenting draft amendments to these substances under REACH.

“Under REACH, D4, D5 and D6 have been identified as substances of very high concern and included in the Candidate List for Authorisation in June 2018 due to their persistent, bioaccumulative and toxic and/or very persistent, very bioaccumulative properties.”

“The use of D4 and D5 in wash-off cosmetic products has been restricted in the EU under the REACH Regulation since January 31, 2020 and another REACH restriction for D4, D5 and D6 in consumer and professional products is under decision-making by the EC,” continues the proposal.

Stricter prohibitions
Under the current REACH Regulation, D4 and D5 are already restricted in wash-off cosmetic products in a concentration equal to or greater than 0.1% by weight. 

However, all three silicones face stricter restrictions. Namely, they shall not be placed on the market as a substance on its own, as a constituent of other substances or in mixtures, reads the proposed draft. D4, D5 and D6 are also restricted to be used as solvents for the dry cleaning of textiles, leather and fur.

The three silicones are also further limited for leave-on cosmetic products. Specific times of enforcement can be viewed here.Cyclosiloxanes are a class of silicone materials, such as D4, D5 and D6.

Call to global action
The Stockholm Convention aims to protect human health and the environment from persistent organic pollutants.

In its proposal, ECHA flags that D4, D5 and D6 can be considered to meet the screening criteria in Annex D of the Stockholm Convention for persistence, bioaccumulation, long-range transport and adverse effects.

“D4, D5 and D6 do not occur naturally in the environment. They are released to the environment mainly as a result of their presence as intentional constituents or impurities in a very wide variety of consumer products and as residual impurities in silicone polymers,” reads the proposal. 

“Globally, the occurrence and distribution of D4, D5 and D6 are shown for humans, wildlife and the environment. Detections include measurements in the Arctic and Antarctica.” These silicones are toxic to aquatic organisms, and D5 is toxic to terrestrial organisms such as plants, flags ECHA.

Based on these reasons, ECHA seeks global action against using D4, D5 and D6. 

By Venya Patel