Hexabromocyclododecane

The production of HBCD has decreased in the last few years and there are already available on the market chemical alternatives to replace HBCD in high-impact polystyrene (HIPS) and textile back-coating. After any alternative becomes available in commercial quantities, it will take some time for the industry to seek qualification and re-certification of polystyrene bead and foam products for fire-rating.

Note that following information is extracted from the risk management evaluation document (UNEP-POPS-POPRC.8-16-Add.3).

The POPRC has concluded that HBCD is likely, as a result of its long-range environmental transport, to lead to significant adverse human health and environmental effects, such that global action is warranted (UNEP/POPS/POPRC.6/13/Add.2). To reduce the risks to human health and the environment the use of HBCD for different applications must be minimized. The target or aim of any risk reduction strategy for HBCD should be to reduce and eliminate emissions and releases taking into consideration the indicative list in Annex F including technical feasibility of possible control measures and alternatives, the risk and benefits of the substances and their continued production and use. In considering any strategy for a reduction in such risks, it is important to consider the availability of substitutes in the sectors of concern. In this regard, the replacement of HBCD by another chemical or non-chemical alternative needs to take account of factors such as:

  • technical feasibility (practicability of applying an alternative technology that currently exists or is expected to be developed in the foreseeable future)
  • costs, including environmental and health costs
  • risk (safety of the alternatives)
  • availability and accessibility of substitutes in the sectors of concern

Based on the submissions from Parties and Observers, there is currently a need for insulation to meet energy efficiency requirements, and specifically flame retarded insulation materials due to specific fire safety requirements in some countries. However, the safety requirements do not identify any specific flame retardant substances or groups of flame retardant substances that have to be used, and the choice has to be done by the manufacturer.

Technically feasible alternatives are commercially available for most of the applications in which HBCD is used. Chemical drop-in alternatives for one-step EPS and XPS production are becoming available in short term. Alternatives include flame retardant substitution, resin/material substitution and product redesign. Several of these alternatives are halogen-free and have been considered to be better alternatives for the environment and health in the following evaluations: ECHA 2009; SWEREA 2010; and KLIF 2010 (Table). However, they may present other risks, such as other harmful substances or dust, that need to be taken into account (LCSP 2006, KLIF 2011c).

When considering chemical alternatives a distinction should also be made between additive flame-retardants and those chemicals that are covalently bound and less subject to release to the environment. Moreover, the inherent flammability of the resins/ materials should be taken into account and where possible non-combustible insulation materials should be considered as should alternative building techniques.

A discussion of different strategies and the availability and suitability of alternatives to HBCD is provided below along with an overview of technically feasible and commercially available alternatives (Table). Some of the alternatives, for example decaBDE, are not permitted in all countries. Additional information is also available in DEPA (2010), SWEREA (2010), KLIF (2011a) and KLIF (2011b).

Table. Summary table of technically feasible and commercially available alternatives to the use of HBCD (based on SWEREA 2010 and Annex F submissions).

Material

Applications

Chemical alternatives

Alternative materials and product redesign techniques

EPS & XPS

Insulation of foundation, walls and ceilings.

Ground deck, parking deck etc.

No ‘drop in’ replacement chemicals commercially available at present for all production processes and regions

For two step EPS production process, in which HBCD can not be used, another flame retardant is used.

EPS and XPS without FRs, using thermal barriers.

Polyisocyanurate foams, including modified urethane foams.

Phenolic foams.

Blankets (fiber batts or rolls) that may contain rock wool, fiber glass, cellulose or polyurethane foam.

Cellular glass, foam glass Polyester batts.

Loose fills that may contain rock wool, fiber glass, cellulose or polyurethane foam.

Reflective insulation systems.

HIPS

Housings of electronic products. Wiring parts.

deca-BDE, Tris(tribromoneopentyl) phosphate/ATO TBBPA-DBPE /ATO, 2,4,6-

Tris(2,4,6-tribromophen oxy)-1,3,5 triazine/ATO, Ethane-1,2- bis(pentabromophenyl)/ ATO,

Ethylenebis(tetrabromop htalimide)/ATO

Alloys of PPE/HIPS or PC/ABS treated with phosphorus containing flame retardants

Textile back coatings

Protective clothing. Carpets.

Curtains. Upholstered fabrics. Tents.

Interiors in public transportation conveyances (e.g., automobiles, trains, aircraft, etc.).

Other technical textiles.

deca-BDE, decabromodiphenyl ethane,

ethylene bis(tetrabromophtalimid e),

chlorinated paraffins, ammonium polyphosphates

Inherently non-flammable materials: wool.

Inherently flame retardant fibers: rayon, polyester fibers, aramids and other synthetic fabrics.

Other textiles with ammonium polyphosphates (APP).

Textiles with intumescent systems.

More

Flame retarded expanded and extruded polystyrene (EPS/XPS)

The biggest application for HBCD use is polystyrene insulation foam production. HBCD use in EPS/XPS could be phased out by using an alternative flame retardant, using alternative insulation materials or alternative building techniques that achieve the same level of fire safety without a flame retardant.

The first consideration would be to avoid the use of HBCD and other flame retardants in cases where no fire hazard exists. These uses include placement of insulation between two non-combustible wall surfaces such as stone or concrete and uses where insulation is placed between building foundations and soil. These design changes could be implemented by the end-product manufacturer (LCSP 2006; KLIF 2011c), and be marketed subject to building code requirements. In addition, flame retardant EPS/XPS may be used e.g. in other underground applications, such as ground frost protection or road/railway/bridge construction on poor load-bearing subsoil. Today, such use takes place in the EU, Scandinavia, USA, Canada, Japan, Thailand and Jamaica (EC 2011; EPS 2011). In Norway, the use of flame-retarded EPS geofoam was discontinued in 2004 and since then there have been no accidental EPS fires (Aabye and Frydenlund 2011). At the construction site the fire-safety is secured by surveillance, fences and careful use of cutting and welding equipment etc.

Drop-in chemical alternatives to HBCD in EPS/XPS applications

According to the Annex F submissions there were no commercially or technically viable drop- in chemical alternatives to HBCD as a flame retardant in XPS production and the most common ‘one- step’ EPS manufacturing process, which is used at least in Europe and generally in North America currently. In March, 2011, an alternative for HBCD in EPS/XPS (Emerald 3000) was announced. In the 'one-step' production process all additives are mixed in the styrene solution prior to polymerisation. In the alternative 'two-step' process the beads are polymerized in the first step without the flame retardant additive and pentane; the possible flame retardant and pentane are added in the second step. In the ‘two-step’ process, the flame retardant must be able to penetrate into the ready-made bead. HBCD penetrates the beads poorly after polymerization, and therefore other flame retardants must be used.

All European and also most North American polystyrene manufacturers use a 'one-step' process, in which no alternative to HBCD that would meet the technical (foam properties, environmental profile) and performance criteria (i.e. delaying ignition and slowing subsequent growth in testing) is currently on the market. According to the HBCD industry, pure styrenic polymers like HIPS, EPS and XPS require brominated flame retardants to reach the desired fire safety standards. The polystyrene industry is in the process of finding alternatives to HBCD jointly with flame-retardant producers. Also US EPA is discussing with the industry new alternatives to HBCD in polystyrene foams, but the conclusions are not yet publicly available.

As stated above, in March, 2011, Great Lakes Solutions announced it will scale up production of a high molecular weight brominated co-polymer of styrene and butadiene flame retardant (EmeraldTM 3000) suitable for EPS and XPS, developed by Dow Chemicals (DOW 2011). It is expected, however, to take several years for the industry to fully convert to this technology. According to the industry hazard assessment, it is persistent, but not bioaccumulative or toxic. The USEPA Design for Environment program will conduct a hazard assessment of HBCD alternatives used in XPS/EPS.

Two production facilities in North America, and possibly others outside Europe, utilise a"two-step" process. It is unclear what is currently used in the "non-HBCD EPS" process, but at least in the past tetrabromocyclooctane and dibromoethyldibromo-cyclohexane were used (LSCP 2006). There are also concerns about the environmental or health properties of these substances.

The Japanese EPS industry is aiming at replacing HBCD in its production processes by the end of 2012 and also the industry producing XPS is working towards reduction in HBCD use by reconsidering HBCD content but also the need for HBCD in the product (Japan 2011).

Alternatives to use of flame retardant EPS/XPS

Flame retarded EPS and XPS foam used for building insulation can also be replaced by alternative insulation materials which according to KLIF (2011b) can fulfil the same insulation and fire safety requirements and be as moisture resistant, and equally rigid or more flexible than flame retardant EPS/XPS. This has been reported as a more complex approach than simple flame retardant substitution because it has a greater effect on overall product cost and performance (LCSP 2006).

The properties of EPS make it especially suitable for insulation of exterior walls, flat roofs, floors and sandwich elements. Technically feasible alternatives for the key uses of flame retarded EPS are commercially available in common insulation materials used worldwide. Alternative materials include polyisocyanurate foams, phenolic foams, blanket insulation, fiberglass, cellular glass, polyester batts, sheep wool and reflective insulation systems including foils, films, or papers (SWEREA 2010), and also encompass insulation products such as polyurethane foams and loose-fill insulation that can be poured in place, spray-applied or blown into the building structure during construction. Flame retardants (such as boric acid) with questionable environmental or health profile may, however, also be used in these materials. Loose-fill insulation consists of small particles of fiber, foam, or other materials (US DOE 2010). These small particles form an insulation material that can conform to any space without disturbing any structures or finishes. This ability to conform makes loose-fill insulation well suited for retrofits and for places where it's difficult to install other types of insulation. The most common types of materials used for loose-fill insulation include cellulose, fibreglass, and mineral (rock or slag) wool. All of these materials are produced using recycled waste materials. Cellulose is primarily made from recycled newsprint. Most fiberglass contains 20%–30% recycled glass. Mineral wool is usually produced from 75% post-industrial recycled content. Loose-fillinsulation can also be produced from materials such as vermiculite or perlite. Cellular glass, perlite and wood fibre insulation boards are considered to be as technically feasible as EPS for all the key uses except for sandwich panels. The different materials available on the market all have different thermal insulation properties, areas of use and require their own installation methods (US DOE 2010, KLIF 2011b). They also vary with regards to fire-safety properties, but there are alternatives that are able to meet the same fire-safety requirements, or higher, as the flame retarded EPS (KLIF 2011b, 2011c).

Polyisocyanurate foams include modified urethane foams that utilize chemical flame retardants such as tris monochloropropyl phosphate (TMCPP, TCPP) and tris chloroethyl phosphate (TCEP). An EU Risk Assessment (ECB 2008) is available for TCMPP, identifying risk only for worker exposure.  In the TCEP manufacturing process ethylene oxide (a carcinogen) is used, and TCEP appears to be a reproductive toxicant, is found in the Arctic indicating long-range transport, and is considered a carcinogen by the California Office of Environmental Health Hazard Assessment. According to LCSP (2006) due to the chlorinated and brominated flame retardants used in the manufacture of polyisocyanurate insulation products, these cannot be considered to be preferable alternatives because of their health effects.

Phenolic foams are in use in roofing, cavity board, external wall board, and floor insulation. They are mostly used to bind glass fiber to make insulation products. One concern over their use is that formaldehyde, a human carcinogen, may be used for making phenolic resins monomer. Formaldehyde is listed by the International Agency for Research on Cancer (IARC) as a known human carcinogen (LCSP 2006). This has to be considered at the production sites, using available emission control techniques and safety restrictions protecting the workers. According to KLIF (2011c) phenolic resin monomers may, however, be produced also without formaldehyde as other alternatives are available.

Blanket insulation is as much a technical alternative as an alternative material. It is usually made of fiber glass or rock wool and can be fitted between studs, joists, and beams. It is available in widths suited to standard spacings between wall studs or floor joists. Continuous rolls can be hand cut and trimmed to fit various spaces. The blankets are available with or without vapour retardant facings. Batts with special flame resistant facing are available where the insulation will be left exposed.

Cellular glass and foam glass can be used in some EPS/XPS insulation applications, such as warm roofing systems, parking decks, roof decks, ventilated facades, indoor insulation, floor insulation in industrial environments, and ground and perimeter insulation. They have a closed cell structure and are made of recycled glass without binders. They are available in different densities for different loadings and do not contribute to fire. They are also impervious to water.

Fiberglass is a synthetic vitreous fiber. Loose-fill insulation is typically blown into place or spray-applied by special equipment. It can be used to fill existing wall cavities and for irregularly shaped areas.

Reflective insulation systems include foils, films, or papers that are fitted between studs, joists, and beams and commonly used to prevent downward heat flow in roof applications. Common materials include foil-faced paper, foil-faced polyethylene bubbles, foil-faced plastic film, and foil- faced cardboard.

Other commonly used insulation materials include polyester batts and sheep wool which can be fitted between studs, joists, and beams.

Fiberglass, glass wool, and mineral wool are considered synthetic vitreous fibers. They also may have occupational health effects. When these fibers are suspended in air they can cause irritation of the eyes, nose, throat, and parts of the lung. Animal studies show that repeatedly breathing air containing synthetic vitreous fibers can lead to inflammation and fibrosis of the lung. (ATSDR 2004). Protective clothing and equipment (face masks, goggles, gloves etc.) are available and used by construction workers to avoid irritations from contact and breathing in the fibres. This will only be of importance in the working environment, since the fibrous material is built inside the wall, foundation and ceilings in the buildings and constructions, and during demolition and refurbishment. In addition fiberglass may be bound into batts using adhesive binders, which can contain phenol formaldehyde, a hazardous chemical known to slowly off-gas from the insulation over many years.

The substitution of HBCD for building and construction purposes may also be aided by product redesign i.e. by technical solutions and changes in building and construction practice. Non-flame retarded EPS boards are used in a number of countries in combination with other construction materials which protect the EPS from catching fire (KLIF 2011a). Examples of product redesigninclude using fire barrier material and other strategies to separate and reduce the source of heat from the product. These design changes could be implemented by the end-product manufacturer (LCSP 2006). By using thermal barriers it may be possible to achieve fire safety without the use of flame retarded EPS/XPS. Thermal barriers are fire resistant coverings or coatings that separate the insulation material from the building interior. The insulation material may for example be placed between two non-combustible wall surfaces such as stone or concrete or between building foundations and soil (LCSP 2006; KLIF 2011c). The technique can be used in constructions such as external facades, floor slabs or flat roofs (KLIF 2011c). In roofs a thermal barrier is placed between the EPS and metal roofing. For applications where the insulation is in direct contact with the ground there is no need of flame retarded plastic foams, since the XPS is typically placed between a concrete slab and the ground and the insulation material is well protected from fire exposure (Klif 2011 c). Thermal barrier materials include: gypsum boards, gypsum or cement plasters, perlite boards, spray-applied cellulose, use of mineral fiber or gypsum coatings and selected types of plywood. All these materials are currently in common use in domestic and commercial building construction (LCSP 2006; SWEREA 2010).

Thermal barriers are subject to country-specific building code requirements (SWEREA 2010), and are currently used in Finland, Norway, Sweden and Spain where the national fire safety requirements are issued by building codes. By considering also technical aspects and solutions such as the use of thermal barriers and  how insulation is implemented in the building construction, the building codes in these countries specify which insulation products may be used and for which type of construction. Hence fire safety may be achieved even when using non-flame retarded EPS/XPS.  It is to be noted, however, that the use of thermal barriers may not be feasible in all countries in the short term due to technical standards, and building codes (SWEREA 2010) and policies. In addition, current fire safety regulations in some countries require the use of a flame retardant in EPS/XPS irrespective of their use, for storage and transportation safety.

The alternative insulation materials/techniques may have characteristics that are different from XPS and EPS and that are more or less appropriate for some specific use scenarios (such as resistance to water absorption, resistance to mechanical loadings (high compression strength) and structural integrity for service life) (ECHA 2009; US DOE 2010). According to the submissions, alternative insulation materials to EPS/ XPS are available for all uses, with the exception of some demanding XPS use in moist or freeze/thaw sensitive applications in North America (XPSA/CPIA 2011). Use of alternative insulation materials/techniques may also incorporate different environmental issues such as increased energy costs during transportation, and may come with their own unique set of health- and/or environmental risks which in most instances are not too well known. When release to the outer environment is not considered, the health effects of any given insulation material is primarily of importance in the work environment, since the insulation material is built inside the wall, foundation and ceilings. Exposure to alternative insulation materials during building repair, refurbishment and demolition must also be considered. The environmental and health properties of several alternative materials were assessed in a recent Norwegian report which concluded that the alternatives contain chemicals that are less problematic than HBCD as none of them are halogenated or have been classified as PBT or have been identified as POPs (KLIF 2011c). However, for polyurethane rigid foams, the majority of the alternative flame retardant chemicals in use are halogenated substances.

Replacing EPS/XPS insulation with other materials can furthermore affect overall product cost and performance, and may additionally require a different approach during building and construction. However, current building practice from Sweden and Norway, where most of the EPS and XPS used is HBCD-free, suggests that fire-safety of building materials and buildings can be obtained at a reasonable cost without the use of HBCD and without altering traditional building and construction techniques to a great extent. According to an analysis on alternatives to flame retardant EPS made in Norway, a change from flame retarded EPS to the alternative insulation materials would consequently not compromise fire safety and the alternatives would in general be able to meet the same requirements, or higher, as the flame retarded EPS. The alternatives, including non-flame retarded EPS in combination with thermal barriers, typically have better fire performance and can compete with regard to the insulation properties and moisture resistance required in most applications in both cold and warm climates (KLIF 2011c). According to KLIF (2011c) the price of the cheapest alternatives ranges from more or less the same price as for flame retarded EPS to approximately 30% more.

Alternatives to HBCD in high impact polystyrene (HIPS) plastic

HBCD is not widely used in HIPS and it is reasonable to assume that alternative flame retardants are available for this application (Table). It is mainly used in V-2 grade HIPS where aliphatic BFRs are more efficient than aromatic BFRs. Decabromodiphenyl oxide (ether)i.e. deca-BDE is the most widely used flame retardant for HIPS due to its low cost and high brominecontent (Weil and Levchik 2009). It is also used in electronic wire insulation. It may, however, not be recommended for use as a substitute for HBCD due to concerns about its impact on human health and the environment (EC 2002; US EPA 2010) as well as debromination to compounds such as PentaBDE and OctaBDE (UNEP/POPS/POPRC.6/2). In the EU, the introduction of the RoHS and WEEE Directives phased out the use of deca-BDE in electronics. In the US, the industry is voluntarily withdrawing Deca-BDE from most uses by 2013.  In Norway, the manufacture, import, export, sale and use of substances and preparations that contain 0.1 percent by weight or more of deca-BDE was banned in 2004.

Other chemicals that can be used as alternatives to HBCD in HIPS include a variety of brominated flame retardants used in conjunction with antimony trioxide (ATO). These include: Tris(tribromoneopentyl)phosphate; Tetrabromobisphenol A-Bis(2,3-dibromopropyl ether)(TBBPA-DBPE); 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5 triazine; Ethane-1,2-bis(pentabromophenyl) and Ethylenebis(tetrabromophtalimide).

Alternative materials to HIPS are also on the market, thus circumventing the problem of finding a chemical substitute to HBCD. More specifically in electrical products HIPS can be replaced by various alternative materials, including blends of polycarbonate / acrylonitrile butadiene styrene (PC/ABS), polystyrene / polyphenylene ether (PS/PPE) and polyphenylene ether / high impact polystyrene (PPE/HIPS6) without flame retardants or with the use of non-halogenated phosphorus flame retardants (Brazil 2011, DEPA 2010). Organic aryl phosphorus compounds, resorcinol bis (biphenyl phosphate), bis phenol A bis (biphenyl phosphate), polymeric biphenyl phosphate, diphenyl cresyl phosphate, triphenyl phosphate (Kemi 2006) appear to require a co-additive to prevent migration of the phosphorus compound to the surface of HIPS. The phosphorus alternatives for HIPS are required to be used at higher loadings (ECHA 2009). The co-polymer blends are widely used in electronic equipment with or without flame retardants, have higher impact strength and are inherently more resistant to burning because they form an insulating char foam surface when heated (DEPA 2010).

Alternatives to HBCD use in textile back-coating

HBCD is used as a flame retardant in the back coating of textiles for upholstered furniture, upholstery seating in transportation vehicles, draperies, wall coverings, mattress ticking, and interior textiles such as roller blinds (LCSP 2006,; ECHA 2009; SWEREA 2010). The typical concentration of HBCD in textile applications is high compared to other applications, at 6 to 15% in a polymer (CEFIC/EFRA 2006, EC 2008). HBCD is relatively expensive, and hence used mainly where companies find that only HBCD meets the performance needs (ECHA 2008b).

Flame retardant use in textiles can be avoided if the material itself is non-flammable or has low flammability. Some natural materials such as wool may therefore be used as barrier materials in furniture (Norway 2011; SWEREA 2010). Other inherently flame retardant materials include rayon with a phosphorus additive, polyester fibers, and aramids (Weil and Levchik 2009). Also several chemicals are available that may be used as drop-in alternatives for HBCD in textile applications. For textile back coating, chemical alternatives to HBCD include deca-BDE, decabromodiphenyl ethane, ethylene bis(tetrabromophtalimide), chlorinated paraffins and ammonium polyphosphates (ECHA 2009; KLIF 2011a). Concerns about deca-BDE are described above. Long chain chlorinated paraffins are reproductive toxicants to humans, show chronic toxicity with effects on liver and kidneys, and are potential carcinogens (ECHA 2009). For different textile sets it is also possible to use ammonium polyphosphate (APP) in the backcoating.

In textiles fire safety may also be achieved by the use of intumescent systems (KLIF 2010). Intumescence is the formation of a foamed char, which acts as heat insulation. An intumescent system is generally a combination of a source of carbon to build up char, an acid generating compound and a decomposing compound to generate blowing gases to produce foamed char (Weil & Levchik 2009). This foam attains a thickness of 10 to 100 times that of the originally applied coating and insulates the substrate material through its low thermal conductivity, making intumescent systems efficient at reducing flammability and the exposure of fume gases (KEMI 2006). Several intumescent systems linked to textile applications have been on the market for about 20 years, and have successfully shown their great potential. Intumescent systems include use of expandable graphite impregnated foams, surface treatments and barrier technologies of polymer materials (SWEREA 2010). Intumescent systems may not be applicable to the same sets of textiles as BFR-based backcoatings.

According to the submission from Japan, HBCD has been replaced in automotive application fabrics used in new car models. However, the supply of fabrics that contain HBCD will continue for some time as these fabrics continue to be used in repair parts for older models (Japan 2011).

For further information, please refer to