ECHA committees support proposal to restrict siloxanes

Helsinki – Two European Chemicals Agency (ECHA) committees have supported a proposal to restrict the use of D4, D5 and D6 siloxanes, the ECHA announced 10 Dec.

D4 (octamethylcyclotetrasiloxane), D5 (decamethylcyclopentasiloxane) and D6 (dodecamethylcyclohexasiloxane) are used as chemical intermediates in the production of a wide range of silicone materials.

The Committee for Socio-economic Analysis (SEAC) and the Committee for Risk Assessment (RAC) threw their weight behind the proposal which limits placing on the market of the siloxanes, as constituents of other substances, or in mixtures in a concentration equal to or greater than 0.1 % w/w of each substance. 

A consultation on the agreed SEAC opinion will begin soon and the committee is expected to adopt an opinion at its March 2020 meeting.

ECHA launched a public consultation in June 2018 for a move to include the intermediates to the REACH candidate list as substances of very high concern (SVHCs).

D4 was deemed to meet the REACH criteria for ‘persistent, bioaccumulative and toxic’ (PBT) substances, and D5 and D6 the criteria for very ‘persistent, very bioaccumulative (vPvB)’ substances.

In addition, D5 and D6 were deemed PBT when they contain more than 0.1% D4 – though no exposure consideration is taken into account for SVHC assessment.

While SVHC candidate listing does not ban or restrict the use of D4, D5 and D6 or of silicone polymers, it does trigger communication and risk-management obligations.

As such, the European regulatory move is seen as a threat to the continued use of silicone polymers in many important applications, including in the healthcare, technology and energy sectors.