Hexabromocyclododecane (HBCDD) uses, CAS numbers and bans

Hexabromocyclododecane (HBCDD) and where it is banned

Hexabromocyclododecane (HBCDD or HBCD) is a brominated flame retardant. Its main use was in EPS and XPS polystyrene foam insulation. The Stockholm Convention listed it in Annex A in 2013. The EU limits it to a trace level, China bans production, use, import and export, and the US has found an unreasonable risk but has no ban yet.

HBCDD CAS and EC numbers

The EU POPs Regulation covers "hexabromocyclododecane, 1,2,5,6,9,10-hexabromocyclododecane and its main diastereoisomers" alpha, beta and gamma (Regulation (EU) 2019/1021):

The EC pairings come from REACH Annex XIV. US EPA groups these as the "Cyclic Aliphatic Bromide Cluster (HBCD)" and adds CAS 3194-57-8 (EPA). Don't use that extra CAS on EU or China filings.

What HBCD was used for

HBCDD was used as a flame retardant additive. Main uses were flame-retarded EPS and XPS foam for insulation and construction, plus back-coatings for upholstery and other interior textiles, including cars, and high impact polystyrene (HIPS) in electrical and electronic appliances (Stockholm factsheet). EPA also lists solder paste, recycled plastics and automobile replacement parts (EPA risk management).

Why it is restricted

HBCDD is persistent, with a strong potential to bioaccumulate and biomagnify, potential for long-range transport, and very toxic to aquatic organisms (Stockholm factsheet). The EU identified it as PBT under REACH Article 57(d) (Regulation 143/2011). Its harmonised CLP classification is Repr. 2 (H361) and Lact. (H362), applying from 1 December 2013 (Regulation 618/2012).

HBCDD ban by jurisdiction

Under the Stockholm Convention, decision SC-6/13 listed HBCDD in Annex A (elimination) in 2013 (POPs list). The listing entered into force on 26 November 2014 (Regulation 2016/293). A time-limited exemption covered EPS and XPS in buildings (overview). The register now shows no registered exemptions. China's, the last, ended on 26 December 2021 (exemptions register).

HBCDD joined the EU Candidate List on 28 October 2008 (ECHA). It is entry 3 of REACH Annex XIV, with a sunset date of 21 August 2015 (corrected Regulation 143/2011). It is still on the Authorisation List. Under the EU POPs Regulation, from 17 October 2024 the unintentional trace limit is 75 mg/kg (0.0075 % by weight), down from 100 mg/kg. The 100 mg/kg limit stays only for recycled polystyrene in EPS or XPS insulation for buildings or civil engineering works (Regulation 2024/2555). The Commission was due to review these limits by 1 January 2026. Check the current consolidated text before you file.

On RoHS, HBCDD isn't one of the 10 substances in RoHS Annex II (Directive 2011/65/EU). HBCDD in EEE plastics is still caught by those POPs limits (POPs Regulation).

In China, HBCDD is entry PC012 in Batch 1 of the Priority Controlled Chemicals List, issued 28 December 2017 (MEE Announcement 2017 No. 83). Production, use, import and export were banned from 26 December 2016, except EPS and XPS in buildings, and except lab-scale research and reference standards (Announcement 2016 No. 84). That building exemption ended on 25 December 2021. From 26 December 2021, no exemption remained, and leftover stock is hazardous waste (MEE notice). HBCDD is also in the phased-out group of the 2023 Key Controlled New Pollutants List (MEE Order No. 28).

In the US, EPA's June 2022 revised risk determination found that HBCD, "as a whole chemical substance, presents an unreasonable risk of injury to health and the environment" (87 FR 38747). No TSCA section 6 rule has been proposed, past the 2021 and 2022 deadlines. The Unified Agenda (RIN 2070-AK71) targeted a proposed rule in September 2026 and a final rule in July 2027. Check the Federal Register for whether the proposal has appeared (EPA, RIN 2070-AK71). HBCD (CAS 3194-55-6 and 25637-99-4) is a TRI PBT chemical from reporting year 2017, 100-pound threshold (81 FR 85440).

Musk xylene, the other Batch 1 entry

Musk xylene (CAS 81-15-2, EC 201-329-4) is a synthetic nitro musk fragrance. Fragrance production shifted from nitro musks toward polycyclic musks, and IFRA voluntarily phased musk xylene out in June 2009 (EPA). It is entry PC003 on China's Batch 1 list. It is not on the 2023 Key Controlled New Pollutants List (MEE, MEE Order No. 28). In the EU it is a vPvB substance on the Candidate List and in REACH Annex XIV, sunset date 21 August 2014 (ECHA, Regulation 143/2011). EU cosmetics still allow it under Annex III entry 96, except in oral products: 1.0 % in fine fragrance, 0.4 % in eau de toilette and 0.03 % in other products. Musk ambrette, moskene and musk tibetene are banned in Annex II (Regulation 1223/2009). Unlike HBCDD, musk xylene is not a Stockholm POP (POPs list).

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