On 8 May 2026, the European Union notified the World Trade Organization (WTO) of a draft Commission Regulation proposing the addition of a new entry to Annex XVII to REACH which would restrict terphenyl, hydrogenated, also known as partly hydrogenated terphenyl (PHT), as a substance on its own and where present in other substances, mixtures, or articles. Under the proposal, the restriction would apply where PHT is present at concentrations of 0.1% w/w or greater.
Stakeholders may submit comments until 7 July 2026. Adoption of the measure is expected during the fourth quarter of 2026.
Restriction Scope and Background
PHT (CAS No. 61788-32-7) is identified under REACH as a very persistent and very bioaccumulative (vPvB) substance and has been included on the Candidate List of substances of very high concern (SVHCs) since June 2018. According to the draft Regulation, releases of PHT may lead to long-term and difficult-to-reverse contamination of the environment and living organisms. The Commission notes that emissions may occur from all uses covered by the proposal, with higher releases associated with its use as a plasticiser, additive, or processing solvent.
PHT is primarily used as a heat transfer fluid at industrial sites operating at high temperatures. Other uses include as a plasticiser in articles and mixtures, such as in cables, sealants, adhesives, paints, inks, electrical and electronic equipment, construction materials, and vehicle parts.
The restriction would prohibit the placing on the market and use of PHT 18 months after the Regulation enters into force. However, civilian aerospace applications, including aircraft, spare parts, maintenance, and repairs, would benefit from a 10-year transitional period.
Permanent Derogations and SCCS Requirements
The proposal includes permanent derogations for the use of PHT as a heat transfer fluid within the temperature range of 250°C to 350°C in strictly controlled closed systems (SCCS) at industrial sites. Defence applications would also be permanently exempted.
The draft Annex establishes detailed SCCS requirements, including leak-tight system design, preventive maintenance, regular leak-tightness checks, continuous monitoring of emissions and worker exposure, procedures for handling hazardous waste, personnel training, and periodic inspections.
End users operating such systems would also be required to confirm in writing to the authority responsible for issuing operating permits that the SCCS conditions are met.
Furthermore, the proposed restriction would not apply to mixtures and articles, including second-hand articles, placed on the EU market before the end of the 18-month transition period. Civilian aircraft placed on the market during the 10-year transitional period could continue to be used until the end of their service life.
