HBCD (Hexabromocyclododecane): Properties, Former Uses in EPS/XPS and Regulatory Status

HBCD (hexabromocyclododecane, also written HBCDD; CAS 25637-99-4) is a cycloaliphatic brominated flame retardant that made expanded and extruded polystyrene insulation flame retardant until it was listed as a persistent organic pollutant. Because HBCD is now controlled as a POP rather than as an ordinary industrial chemical, the practical question has changed from how to use it to how much of it may legally remain in a material.

HBCD has been on the REACH Candidate List since 28 October 2008 as a PBT substance, sits on REACH Annex XIV as entry 3 with a sunset date of 21 August 2015, was listed in Annex A of the Stockholm Convention at COP-6 in May 2013, and appears in Annex I Part A of the EU POPs Regulation (EU) 2019/1021 with an unintentional-trace-contaminant limit of 100 mg/kg. HBCD is one of 87 flame-retardant pages in our directory of plastic additives, each with the same identity, dosage and regulatory fields.

This page carries the identity data and the three diastereomers, the two correct CAS numbers and the one wrong one, the measured physical constants, the polymers and applications that used HBCD before the bans, the limiting oxygen index target that polystyrene foam had to reach, the dated restriction matrix across the EU, the Stockholm Convention, the United States, Canada and Japan, the replacement chain to PolyFR and expandable graphite, and what legacy HBCD means for recovered polystyrene today.

Table T1. HBCD identity card.

Footnote: identity and physical data from PubChem CID 33121 and ECHA CHEM 100.042.848; regulatory entries from the ECHA obligation lists, the EU POPs Regulation, the Stockholm Convention listings and the US, Canadian and Japanese legal texts cited in each section. Status as of 23 September 2026.

What Is HBCD (Hexabromocyclododecane)?#

HBCD is a twelve-membered carbon ring carrying six bromine atoms (C12H18Br6, molecular weight 641.7 g/mol), which makes it a cycloaliphatic brominated flame retardant rather than an aromatic one like TBBPA or the PBDEs. The ring is saturated, so every carbon-bromine bond sits on an sp3 carbon instead of on an aromatic ring. Why does the aliphatic ring matter? Carbon-bromine bonds on an aliphatic ring break at a lower temperature than the same bonds on an aromatic ring, and the measured consequence for this substance is recorded in its physical data: HBCD decomposes above 190 °C (374 °F) rather than reaching a boiling point.

HBCD was an additive flame retardant, blended physically into the polymer melt or into the bead and never reacted into the polystyrene backbone, which is also why the material could later be recovered from a foam board as an intact molecule. The US Environmental Protection Agency describes the commercial material by exactly that physical character in its TSCA work, calling it the cyclic aliphatic bromide cluster. As an additive flame retardant, HBCD belonged to the bromine branch of the family; the hub on flame retardants for plastics compares all classes, from the brominated and chlorinated halogen types to phosphorus esters, metal hydroxides, nitrogen systems and mineral intumescents. In appearance the substance is an unremarkable white powder, which says nothing about its regulatory position and everything about why it blended easily into a polystyrene bead.

What does HBCD stand for, and is HBCDD the same substance?#

HBCD stands for hexabromocyclododecane, and HBCDD is the same substance under a second abbreviation that ECHA and the Stockholm Convention prefer because it spells out both "cyclo" and "dodecane". The US EPA calls the commercial material the cyclic aliphatic bromide cluster in its TSCA documents, which is why an EPA search for HBCD returns that phrase rather than the chemical name. Four further synonyms describe the same material in different registries: 1,2,5,6,9,10-hexabromocyclododecane for the defined isomer, and alpha-HBCD, beta-HBCD and gamma-HBCD for the three diastereomers that make up the commercial mixture.

Which CAS number is correct for HBCD?#

Two CAS numbers are correct for HBCD: 25637-99-4 covers hexabromocyclododecane with unspecified isomers, which is the commercial material, and 3194-55-6 covers the defined 1,2,5,6,9,10-isomer. Each number carries its own EC number, 247-148-4 for the unspecified-isomer entry and 221-695-9 for the defined isomer, and regulatory instruments differ in which of the two they cite. Both numbers describe hexabromocyclododecane, so a declaration that names only one of them is incomplete rather than wrong. Most encyclopaedic and AI-generated summaries of this substance print a single CAS number, which is the first place a compliance document can go astray: the identity block below names both, plus the number that does not belong to HBCD at all.

Why CAS 3194-57-8 is not HBCD#

CAS 3194-57-8 is not hexabromocyclododecane: it is 1,2,5,6-tetrabromocyclooctane (TBCO), a different brominated ring compound, and quoting it on a safety data sheet or a declaration of compliance is a common documentation error. TBCO carries four bromine atoms on an eight-membered ring, while HBCD carries six on a twelve-membered ring, so the two substances share a family resemblance and nothing else, including their regulatory status.

What are the alpha, beta and gamma isomers of HBCD?#

Commercial HBCD is not a single compound but a mixture of three diastereomers, alpha-HBCD, beta-HBCD and gamma-HBCD, and the proportions in the mixture are why published melting points span 175 to 195 °C (347 to 383 °F) rather than sitting at one value. The three isomers share the formula C12H18Br6 and the molecular weight of 641.7 g/mol, and they differ in the spatial arrangement of the six bromine atoms around the ring. That is the reason the CAS registry needs an unspecified-isomer entry, 25637-99-4, for the substance as traded, next to the defined-isomer entry 3194-55-6 for the single compound.

The 3 named diastereomers of commercial HBCD are listed below.

• alpha-HBCD, one of the three diastereomers named as a synonym of the commercial material.
• beta-HBCD, the second diastereomer of the same mixture.
• gamma-HBCD, the third diastereomer of the same mixture.

Our source library records the three isomer names and records that the melting point depends on the isomer mix. It does not record the percentage split of the three in commercial HBCD, their relative bioaccumulation or any thermal rearrangement between them, so this page states none of those.

How Did HBCD Make Polystyrene Foam Flame Retardant?#

HBCD worked in the gas phase: above about 190 °C (374 °F) it decomposed and released hydrogen bromide, which scavenged the H· and OH· radicals that carry a flame, replacing them with the far less reactive bromine radical. A flame propagates through a chain reaction of hydrogen and hydroxyl radicals in the gas above the burning surface, and a halogen donor interrupts that chain rather than cooling the polymer or building a barrier on it. The gas-phase route is what brominated flame retardants share, from HBCD to decaBDE and TBBPA, and it is a class mechanism rather than a measurement made on HBCD itself.

Did HBCD also act in the condensed phase? Our source library records the gas-phase mechanism for halogenated flame retardants as a class and records no char-forming or condensed-phase action for HBCD, so this page claims none. That distinction matters for anyone comparing HBCD with a phosphorus ester or a mineral intumescent, because those families work partly or wholly in the condensed phase, on the polymer itself. Gas-phase and condensed-phase action are compared on how flame retardants work.

The gas-phase sequence runs in 4 steps.

1. Heat breaks the carbon-bromine bonds on the aliphatic ring, which happens above about 190 °C (374 °F) for HBCD.
2. Release hydrogen bromide into the gas layer above the polymer surface.
3. React HBr with the H· and OH· radicals that propagate the flame, forming the much less reactive bromine radical.
4. Recycle the bromine radical back into the same sequence, so a small mass fraction of flame retardant inhibits a large flame.

What Are the Physical and Chemical Properties of HBCD?#

The measured constants for HBCD are collected below, each with the unit it is reported in.

Table T2. Physical and chemical properties of HBCD.

HBCD is a white powder that melts between 175 and 195 °C (347 and 383 °F) depending on its isomer mix, decomposes above 190 °C (374 °F) instead of boiling, and carries 74.7 % of its mass as bromine. A bromine content of 74.7 wt% is the property that made a small addition worth making at all, because the active element is the bromine and not the carbon ring that carries it. The melting and decomposition ranges overlap, which is an observation worth stating plainly: a substance that begins to decompose at 190 °C while part of its isomer mix is still melting at 195 °C has a narrow usable window between the two, and that window, not the melting point alone, is the number a process engineer reads. The density of 2.40 g/cm3 is close to four times that of the compacted polystyrene bead the powder was blended into.

Which Polymers Used HBCD, and at What Dosage?#

HBCD was used almost entirely in polystyrene foam, in both expanded polystyrene (EPS) and extruded polystyrene (XPS) insulation boards, with smaller volumes in high-impact polystyrene and in textile back-coatings. How much HBCD did a board contain? World production of the substance ran at about 28,000 tonnes a year in 2009 and 2010 according to the UNEP figure, but no verified loading level for EPS, XPS or HIPS sits in our source library, so this page states the scale of the use and not a percentage. A loading figure in wt% or phr will be added here only when a primary source supplies one.

Table T3. Polymers that used HBCD.

Polystyrene is a single polymer family with four commercial forms, GPPS, HIPS, EPS and XPS, and HBCD touched three of them. The full package for GPPS, HIPS, EPS and XPS, from impact modifiers and antioxidants to the current flame retardants, sits on additives for polystyrene.

HBCD in EPS (expanded polystyrene)#

EPS insulation board needed a flame retardant because the material is 95 to 98 % air with a density of only 11 to 32 kg/m3, and unmodified polystyrene has a limiting oxygen index of about 18 vol% oxygen against the more than 24 vol% that ASTM C578 requires. A limiting oxygen index of 18 vol% oxygen sits below the 21 vol% of ambient air, which states the problem in one number: the unmodified polymer sustains flaming combustion in normal air. The foam structure sharpens the problem rather than softening it, because a board that is 95 to 98 % air presents an enormous surface area of polymer to the flame for every kilogram of material.

EPS is made by expanding polystyrene beads with pentane and then steam-moulding them into blocks or boards, so any additive has to be present in the bead before expansion. HBCD entered the process at that point rather than at a melt-compounding step. Our source library records the unmodified limiting oxygen index of about 18 vol% and the ASTM C578 requirement of more than 24 vol%, and it records no measured limiting oxygen index for HBCD-modified EPS, so this page does not state one.

HBCD in XPS (extruded polystyrene)#

XPS board is the denser of the two polystyrene foams at 28 to 34 kg/m3, with a thermal conductivity of 0.029 to 0.039 W/(m·K) and an average near 0.035, and it carried HBCD through a melt-extrusion step rather than a steam-moulding step. An extrusion route exposes the additive to melt temperature and shear for a defined residence time, which is where the decomposition threshold above 190 °C (374 °F) becomes a process limit rather than a laboratory number. Current EPS and XPS systems are compared on flame retardants for polystyrene, EPS and XPS.

Two separate regulatory stories hit XPS board in the same decade, and readers routinely conflate them. The HBCD restrictions are a flame-retardant matter, while Regulation (EU) 2024/573 on fluorinated greenhouse gases addresses the blowing agent, banning XPS that contains hydrofluorocarbons with a global warming potential of 150 or more from 1 January 2020. A board can therefore be non-compliant on the blowing agent, on the flame retardant, or on both, and the two instruments have different dates and different scopes.

HBCD in HIPS and in textile back-coatings#

HBCD also went into high-impact polystyrene and into textile back-coatings, both in far smaller volumes than insulation board. Textile finishing falls outside the border of this site, which covers additives in plastics, so the textile use is named here as part of the historic record and is not developed further.

What Was HBCD Used For? 3 Former Applications in Plastic Foam and Plastics#

HBCD is not used in any new plastic product today; its 3 former applications were building insulation boards in EPS and XPS, high-impact polystyrene parts, and textile back-coatings. The 3 former applications are listed below in order of the volume they consumed.

• Building insulation boards in EPS and XPS, the dominant market, including the board stock used in walls, roofs, floors and perimeter insulation.
• High-impact polystyrene parts, a far smaller volume than insulation board.
• Textile back-coatings, a historic use outside the plastics border of this site.

Foam is a distinct formulation problem rather than a variant of solid-polymer compounding, because the cell structure changes both the fire behaviour and the way an additive has to be introduced. Foam-specific additive packages for EPS, XPS, PU and PE foam are on additives for plastic foams.

Building insulation boards, SIPs and ICFs#

Building insulation was HBCD's dominant market: EPS and XPS boards, the EPS cores of structural insulated panels and the foam shells of insulated concrete forms all had to meet reaction-to-fire classes under EN 13501-1 in Europe and DIN 4102 in Germany. A structural insulated panel (SIP) is a sandwich of two structural facings bonded to an insulating foam core, usually EPS, and an insulated concrete form (ICF) is a permanent formwork of foam shells that concrete is poured into. Both product forms are built around the same EPS board stock, so the flame-retardant question they faced was the EPS question.

Reaction-to-fire classification is the reason a flame retardant was in the board at all. EN 13501-1 classifies construction products by their reaction to fire, and DIN 4102 is the German building-materials classification that preceded and still accompanies it. Our source library records that polystyrene foam boards are built to meet these classes, and it does not attach a specific class letter to an HBCD formulation, so none is stated here. Insulation, profiles and roofing requirements are collected under additives for building and construction.

Which uses ended first, and when#

The EU use ended first by law: after the REACH sunset date of 21 August 2015, HBCD could be used in the EU only under an authorisation, and Japan had banned it under the Chemical Substances Control Law in May 2014. The authorisation route itself had closed earlier, because the latest application date under Annex XIV entry 3 was 21 February 2014, and a company that had not applied by that date could not continue after the sunset date at all.

The United States took a different route and arrived at a similar market outcome. US manufacturers report complete replacement of HBCD, which happened without a federal ban, while the EPA worked through the TSCA risk evaluation it published in September 2020 and the revised unreasonable-risk determination it issued in June 2022. One standing rule survives all of this: EPS and XPS installed in buildings before 21 February 2018 may remain in use under the EU POPs Regulation, so the substance is still legally present in the European building stock even though it may not be placed on the market.

How Did HBCD Perform in Polystyrene Foam? LOI and Fire Classes#

The performance target HBCD had to hit is documented even though its own performance data are not: unmodified expanded polystyrene has a limiting oxygen index of about 18 vol% oxygen, and ASTM C578 requires more than 24 vol% for insulation board. What limiting oxygen index did HBCD-modified EPS reach? Our source library records the unmodified value and the specification threshold, and it records no measured value for HBCD-modified foam, so this page states the gap rather than filling it.

The limiting oxygen index is the minimum oxygen concentration, in volume per cent of a flowing oxygen and nitrogen mixture, that just supports flaming combustion of a test specimen. ASTM D2863, currently ASTM D2863-23e1, defines the test in three procedures, A for top-surface ignition, B for propagating combustion and C for a short comparison, and ISO 4589-2 is the equivalent international method at ambient temperature. The method behind the 18 vol% figure, ASTM D2863, is explained on limiting oxygen index (LOI).

Polystyrene insulation board is not qualified to UL 94. The relevant specifications are ASTM C578 for the board itself in North America, and the reaction-to-fire classifications EN 13501-1 and DIN 4102 in Europe, which assess a construction product in an end-use scenario rather than a plastic bar in a laboratory flame.

Table T4. Fire-performance indicators for polystyrene foam insulation.

How Did HBCD Interact with Other Additives? Synergists, Stabilizers and Processing Limits#

Three interactions matter for an HBCD-containing foam, and the first is the classic halogen synergist: antimony trioxide reacts with hydrogen halide to form antimony oxyhalide and volatile antimony trihalide in a stepwise sequence, which inhibits flame radicals in the gas phase more efficiently than the halogen alone. The 3 interactions are listed below.

1. Antimony trioxide as the halogen synergist, CAS 1309-64-4, classified Carc. 2 H351 under the CLP Regulation, the standard partner for brominated flame retardants across HIPS, ABS, PP, PBT and PA.
2. The 190 °C (374 °F) decomposition ceiling, which sets the processing constraint for any compound containing HBCD, because the flame retardant starts to release its bromine at that temperature whether or not a flame is present.
3. Stabilizer packages, which the industry re-specified when it moved from HBCD to polymeric flame retardants.

One honesty point separates this page from the general literature on halogen synergism. Our source library records the antimony trioxide mechanism as general halogen chemistry, and it records no antimony trioxide content for HBCD-containing polystyrene foam, so the synergist is described here as class chemistry and is not attributed to any HBCD formulation. The stepwise oxyhalide chemistry behind the antimony trioxide synergist is on its own page, with the dosage data for the polymers where the pairing is documented.

What Is the Regulatory Status of HBCD?#

HBCD is a Substance of Very High Concern, a REACH Annex XIV authorisation substance whose sunset date passed on 21 August 2015, a Stockholm Convention Annex A persistent organic pollutant since COP-6 in May 2013, and an EU POPs Annex I substance with an unintentional-trace-contaminant limit of 100 mg/kg (status 23 September 2026). Six jurisdictions and instruments are compared below, each with the date that fixes the obligation.

Table T5. HBCD regulatory matrix, as of 23 September 2026.

Table T6. HBCD regulatory timeline, 2008 to 2026.

Seventeen years separate the first Candidate List entry from the Canadian regulations that come into force in June 2026, and the sequence reads as one instrument handing the substance to the next. Bans, furniture standards and UL and IEC requirements for this additive class are collected under flame retardant regulations.

Is HBCD an SVHC, and did it need REACH authorisation?#

Yes to both: HBCDD went onto the REACH Candidate List on 28 October 2008 as a PBT substance under Article 57(d), and it was moved to Annex XIV as entry 3, where the latest application date was 21 February 2014 and the sunset date was 21 August 2015. PBT stands for persistent, bioaccumulative and toxic, and Article 57(d) is the route by which a substance meeting the PBT criteria of REACH Annex XIII becomes a Substance of Very High Concern without needing a carcinogenicity or reproductive-toxicity classification. HBCDD was in the first batch added to the SVHC Candidate List on 28 October 2008, together with DEHP, DBP, BBP and SCCP.

A sunset date is the date after which a substance on Annex XIV may not be placed on the market or used in the EU unless the Commission has granted an authorisation for that specific use. The authorisation route then lost its practical relevance for this substance, because the POPs listing that followed in 2016 prohibits the substance outright rather than conditioning it on an authorisation, which is why a compliance question about HBCD today is answered from the POPs Regulation and not from Annex XIV. Entry 3 and its sunset date sit among the other additives on the REACH Annex XIV authorisation list.

Is HBCD banned in the EU?#

Yes: HBCD is banned in the EU under the POPs Regulation (EU) 2019/1021, which lists it in Annex I Part A with an unintentional-trace-contaminant limit of 100 mg/kg, a stricter and simpler rule than the REACH authorisation it replaced. One standing exception applies to material already in place: EPS and XPS installed in buildings before 21 February 2018 may remain in use. Manufacture, placing on the market and use of the substance itself are prohibited, with the 100 mg/kg figure functioning as a contamination threshold rather than a permitted addition level.

Is HBCD a POP under the Stockholm Convention?#

Yes: HBCD was listed in Annex A of the Stockholm Convention at COP-6 in May 2013 under decision SC-6/13, the annex that requires elimination, and the time-limited exemption for EPS and XPS in buildings has expired. Annex A is the elimination annex, distinct from Annex B, which restricts, and Annex C, which addresses unintentional production, so an Annex A listing commits every Party to eliminating production and use rather than to managing it.

HBCD was neither the first nor the last flame retardant to take this route. The Stockholm Convention listed the tetra- to heptabrominated diphenyl ethers and hexabromobiphenyl at COP-4 in 2009, HBCD at COP-6 in 2013, decaBDE and short-chain chlorinated paraffins at COP-8 in 2017, Dechlorane Plus at COP-11 in 2023 and medium-chain chlorinated paraffins at COP-12 in 2025. Every additive POP and its limit value is tabulated on POPs in plastics.

What does the 100 mg/kg UTC limit for HBCD mean?#

The 100 mg/kg limit means that a substance, mixture or article may contain HBCD only as an unintentional trace contaminant at or below 0.01 % by weight, which is the concentration that decides whether recovered polystyrene can legally re-enter production. The limit is not a permitted use level, because use of the substance is prohibited; it is the threshold below which residual contamination does not make the material itself unlawful. The 100 mg/kg figure is a limit for an unintentional trace contaminant (UTC), not a permitted addition.

Compared with its peers in Annex I of the EU POPs Regulation, 100 mg/kg sits in the middle of the range: the unintentional-trace-contaminant limit for the sum of tetra- to decabromodiphenyl ethers is 10 mg/kg under Delegated Regulation (EU) 2025/1482, while Dechlorane Plus runs at 1,000 mg/kg until 15 April 2028 and at 1 mg/kg after that date.

Is HBCD still allowed in the United States under TSCA?#

The United States has not banned HBCD under TSCA: the EPA published its final risk evaluation for the cyclic aliphatic bromide cluster in September 2020, issued a revised unreasonable-risk determination in June 2022, and the risk-management rule that follows such a determination is still under development. The market answer differs from the legal answer, because US manufacturers report complete replacement of HBCD, so the absence of a rule has not kept the substance in US insulation board.

One structural reason explains why the US track looks different from the European one. The United States is not a Party to the Stockholm Convention, so the 2013 Annex A listing created no direct US obligation, and the substance had to travel the full TSCA route of risk evaluation, unreasonable-risk determination and rulemaking instead. How risk evaluations become rules is explained on TSCA and plastic additives.

Is HBCD restricted in Canada and Japan?#

Both countries restrict HBCD: Canada's Prohibition of Certain Toxic Substances Regulations, 2025 (SOR/2025-270) lists it as item 13 with an incidental-presence limit of 100 mg/kg, in force on 30 June 2026, and Japan banned it under the Chemical Substances Control Law in May 2014. The Canadian regulations were registered on 12 December 2025 and replace the 2012 version of the same instrument, SOR/2012-285, and they carry one time-limited allowance: replacement parts for land motor vehicles may contain HBCD until 31 December 2031.

Canada's 100 mg/kg incidental-presence limit matches the EU unintentional-trace-contaminant value of 100 mg/kg, which is a convergence that matters to anyone writing a single global specification for recovered polystyrene. Japan reached the same destination earlier and by a different mechanism, listing HBCD as a Class I Specified Chemical Substance under the Chemical Substances Control Law in May 2014, which is the Japanese category for substances whose manufacture, import and use are prohibited in principle.

Is HBCD Toxic? Health, Safety and Environmental Profile#

HBCD carries a harmonised classification under the EU CLP Regulation, index 602-109-00-4: Repr. 2 (H361, suspected of damaging fertility or the unborn child) and Lact. (H362, may cause harm to breast-fed children), together with aquatic hazards recorded in PubChem. A harmonised classification is binding on every supplier in the EU, which distinguishes it from a self-classification that a single company assigns. HBCD appears on our list of toxic plastic additives because of its PBT and POP status, not because of an acute-toxicity value.

Three findings define the HBCD hazard profile.

• The harmonised CLP classification, Repr. 2 H361 and Lact. H362 under index 602-109-00-4 as introduced by the third adaptation to technical progress, plus the aquatic hazards recorded in PubChem.
• PBT status, meaning persistent, bioaccumulative and toxic, which is the basis on which HBCDD was added to the REACH Candidate List on 28 October 2008 under Article 57(d).
• POP status, the basis for elimination under Annex A of the Stockholm Convention since COP-6 in May 2013, and the label under which HBCDD appears in our flame-retardant hazard summary.

The three findings share a common feature: none of them is an acute-toxicity number. HBCD was eliminated because it persists in the environment, accumulates in organisms and reaches places far from where it was used, and the regulatory instruments that removed it are written around those properties rather than around a dose. Our source library holds no HBCD-specific LD50, no NOAEL, no environmental half-life and no biomonitoring concentration, so this page states none of those values. The class-wide evidence on brominated flame retardants, including the studies behind the recurring public question about fire retardants and human health, is reviewed on flame retardants and human health.

What Replaced HBCD in EPS and XPS? Polymeric and Mineral Alternatives#

Two alternatives replaced HBCD in polystyrene foam: PolyFR, a brominated butadiene-styrene block copolymer that became the industry's direct substitute in EPS and XPS, and expandable graphite, a mineral intumescent used in halogen-free systems. The two are compared with HBCD below on the properties that decide a substitution.

Table T7. HBCD and its two replacements in polystyrene foam.

Footnote: trade names for PolyFR are Emerald Innovation 3000 (LANXESS), FR-122P (ICL) and GreenCrest (Albemarle). No loading level for any of the three substances in polystyrene foam is recorded in our source library.

A polymeric flame retardant is not a new chemistry so much as a new molecular size class, which is what made the substitution work without redesigning the foam. PolyFR belongs to the class covered on polymeric flame retardants, next to brominated polystyrene and the polyphosphonates.

PolyFR (brominated butadiene-styrene copolymer)#

PolyFR is a brominated butadiene-styrene block copolymer, CAS 1195978-93-8, with a bromine content of about 65 wt% and a molecular weight of roughly 100,000, and it is sold as Emerald Innovation 3000 by LANXESS, FR-122P by ICL and GreenCrest by Albemarle. A molecular weight near 100,000 against 641.7 g/mol for HBCD is the single structural difference that separates a polymeric flame retardant from a small molecule, and it is stated here as the measured contrast that it is, without any migration or bioavailability claim that our source library does not record.

PolyFR is not on the REACH Candidate List, which is a regulatory status and not a safety verdict. Its physical data differ from HBCD's in ways that matter to a foam line: ICL reports a softening point of 120 to 140 °C (248 to 284 °F) for FR-122P, and the density is 1.6 g/cm3 against 2.40 g/cm3 for HBCD. The polymer route reached EPS and XPS through three suppliers, LANXESS, ICL Industrial Products and Albemarle, each with its own trade name for the same CAS number. PolyFR (brominated butadiene-styrene copolymer) is the HBCD replacement that EPS and XPS producers adopted.

Expandable graphite#

Expandable graphite is the halogen-free route: its flakes expand from about 200 °C (392 °F), within a reported range of 140 to 230 °C (284 to 446 °F), forming an insulating worm-like char that shields the polymer surface. The intercalant trapped between the graphite layers decomposes on heating, and the gas pressure exfoliates the flake into a voluminous carbon structure, which is a condensed-phase mechanism rather than the gas-phase radical chemistry that bromine uses.

Expansion onset and processing ceiling sit close together, which is the constraint the material imposes: expandable graphite is normally processed below 230 °C (446 °F), because a melt above that temperature begins to expand the flakes in the machine rather than in the fire. Expandable graphite is CAS 12777-87-6, EC 235-819-4, and it is the halogen-free intumescent used beside the polymeric brominated route.

What the replacement changed in the foam plant#

The switch to a polymeric flame retardant changed the stabilizer package as well as the flame retardant: Songwon markets SONGXTEND 1301 specifically as a stabilizer for EPS and XPS containing polymeric flame retardants. A product positioned that precisely is evidence that the replacement was not a drop-in swap of one powder for another, because a stabilizer developed for the new flame retardant would be unnecessary if the old package had continued to work unchanged.

The thermal numbers point the same way. PolyFR softens at 120 to 140 °C (248 to 284 °F) while HBCD decomposes above 190 °C (374 °F), so the two additives meet a foam process at different points on the temperature scale. Our source library holds one plant-level fact for this transition, the SONGXTEND 1301 positioning, and no extruder temperatures, screw designs or pre-expander settings, so this page adds none.

Is HBCD Still Manufactured or Sold? Production, Market Exit and Suppliers#

HBCD is no longer supplied as a flame retardant: US manufacturers report complete replacement, the EU sunset date passed on 21 August 2015, and the only HBCD offered commercially today is the analytical standard that laboratories use to test for it. Analytical-standard listings from laboratory suppliers are what a search for the CAS number now returns, in milligram quantities and at reference-material prices, which is a different market from the tonnage trade that existed before the listings.

World production ran at about 28,000 tonnes a year in 2009 and 2010 according to the UNEP figure, and that scale is the reason legacy HBCD is still a live compliance question rather than a historical footnote. Our source library records no producer names and no trade names for HBCD, so this page names none. Producers of the current EPS and XPS flame retardants are listed in the directory of flame retardant manufacturers and suppliers, and how the bromine volume redistributed after the HBCD exit is tracked on flame retardants market.

Buyers who find HBCD offered for sale should check the POPs status in their own jurisdiction before responding to the offer, because an offer of a Stockholm Annex A substance in the EU, Canada or Japan is an offer of a prohibited material.

How Does Legacy HBCD Affect Polystyrene Recycling Today?#

HBCD is now a recycling problem rather than a formulation choice: insulation boards installed before 2015 are still in buildings, and when those boards are demolished the recovered polystyrene carries HBCD with it. A legacy additive is an additive that is now restricted but survives in long-lived products and returns to the material stream through recycling, and HBCD is one of the legacy additives in recycled plastic, alongside decaBDE, lead, cadmium, DEHP and short-chain chlorinated paraffins. Insulation board is close to the worst case for this effect, because a board installed in 2010 may stay in a wall for 40 years before anyone sees it again.

The EU POPs Regulation governs what happens next through its low-content limits. Recovered polystyrene that carries HBCD above 100 mg/kg cannot lawfully re-enter production in the EU, and material at or below that concentration can, which turns a single analytical number into the decision point for a whole waste stream. Recyclers handling demolition EPS should test against the 100 mg/kg limit before the material re-enters production.

Restabilization is the second half of the problem, because recovered polystyrene needs a fresh additive package regardless of what the old one contained. Restabilization and contamination limits for recyclate are on additives for recycled plastics.

How is HBCD detected in EPS and XPS waste? Additive analysis methods#

HBCD in a foam sample is found in two steps: a total-bromine screen flags the sample, and a deformulation method such as pyrolysis gas chromatography mass spectrometry (Py-GC-MS, pyrolysis at 600 to 1,000 °C) identifies which brominated substance is present. A bromine screen answers only whether bromine is present, not which of the brominated flame retardants carries it, which is why the second step is unavoidable when the legal limit is substance-specific.

Py-GC-MS matches pyrolysis fragments against a reference library, with the NIST Polymer Pyrolysis Search library described by Erisman and co-authors in Environmental Science and Technology in 2026 as the current reference set for polymer additive work. Detection limits, sample masses and recovery percentages for HBCD in foam are not recorded in our source library, so none is given here. Py-GC-MS and the other identification routes are described on additive analysis and deformulation of plastics.

Which brominated flame retardants are restricted or under review?#

Three brominated flame retardants beyond HBCD carry a restriction or a pending one: decaBDE, TBBPA and DBDPE. Each entered the REACH Candidate List on its own date and on its own hazard ground, and their current positions differ sharply.

Table T8. Brominated flame retardants with a restriction or a pending one.

Is HBCD legal?#

No, HBCD is not legal to use in new plastics in the EU, Canada or Japan: it is a Stockholm Convention Annex A substance, an EU POPs Annex I substance with a 100 mg/kg trace limit, a Canadian SOR/2025-270 item 13 substance and a Japanese Chemical Substances Control Law Class I substance. The United States is the exception in form rather than in effect, with no ban in place, only a TSCA unreasonable-risk determination from June 2022 and a risk-management rule still under development. One legal presence remains in Europe: EPS and XPS installed in buildings before 21 February 2018 may stay where they are.

What is HBCD used for today?#

HBCD has no current use in plastics: its remaining presence is legacy material in insulation installed before the bans and the analytical standards laboratories buy to test for it. Every use recorded for the substance, in EPS and XPS insulation board, in high-impact polystyrene and in textile back-coatings, is a past use.

HBCD the flame retardant vs the HBCD study, HBCD supplement and Hiren's BootCD#

The acronym HBCD has 4 unrelated meanings, and only one is a plastic additive: hexabromocyclododecane, the flame retardant on this page. The other three are the HEALthy Brain and Child Development Study, a US child-development research programme; highly branched cyclic dextrin, a sports-nutrition carbohydrate sold as an HBCD supplement; and Hiren's BootCD, a computer recovery disc. Anyone comparing HBCD with maltodextrin has arrived at the carbohydrate meaning, which shares nothing with the brominated flame retardant except four letters.