The European Commission is seeking a Decision that would enable it to submit a proposal, under the UN Stockholm Convention on persistent organic pollutants (POPs), for the listing of octamethylcyclotetrasiloxane (D4).

The proposed Decision says D4 should be added to "Annex A, B and/or C". These, respectively, relate to the elimination, restriction or unintentional production of a substance.

The Commission says D4 should be added to the convention because of its long-range
environmental transport (LRT) potential to remote regions, such as the Arctic, where it can be found in a wide range of organisms. Due to its LRT potential, it says, measures taken nationally, or at EU level, are not sufficient to safeguard the high level of protection of the global environment and human health.

At meetings in early March, Echa’s Committees on Risk Assessment (Rac) and Socio-economic Analysis (Seac) backed proposed restrictions under REACH on D4 and another siloxane, D5.

Following proposals brought to the committees by the UK competent authority, Echa found that D4 and D5 fulfil the REACH Annex XIII criteria for persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB) substances in the environment.

The main use of D4 and D5 is as a feedstock for the production of silicone polymers. According to the Echa dissemination website, the registered tonnage band for D4 is 100,000 to 1,000,000 tonnes a year.