Brominated flame retardants hexabromocyclododecanes

Keywords Bioaccumulation, Bioavailability, Brominated flame retardants, Hexabromocyclododecane, Polybrominated diphenyl ether... 

Morris, S., Bersuder, R, Allchin, C. R., Zegers, B., Boon, J. R, Leonards, R. E. G., de Boer, J. (2006) Determination of the brominated flame retardant, hexabromocyclododecane, in sediments and biota by liquid chromatography-electrospray ionisation mass spectrometry. TrAC, 25 343-349. 

Due to their adverse health effects, several restrictions and bans have been imposed on the usage of polybrominated diphenyl ethers (PBDEs), namely the penta-, octa-, and deca-BDE formulations, in Europe, China, North America, and Japan (http //www. bsef.com). The restricted usage of these PBDEs increased the market demand for substitute brominated flame retardants (BERs) including hexabromocyclododecanes... 

Driffield M, Harmer N, Bradley E, Fernandes AR, Rose M, Mortimer D, Dicks P (2008) Determination of brominated flame retardants in food by LC-MS/MS diastereoisomer-specific hexabromocyclododecane and tetrabromobisphenol A. Food Addit Contamin... 

Saegusa Y, Fujimoto H, Woo GH, Inoue K, Takahashi M, Mitsumori K, Hirose M, Nishikawa A, Shibutani M (2009) Developmental toxicity of brominated flame retardants, tetrabromo-bisphenol A and 1,2,5,6,9,10-hexabromocyclododecane, in rat offspring after maternal exposure from mid-gestation through lactation. Reprod Toxicol 28 456-467... 

The term brominated flame retardant (BFR) incorporates more than 175 different types of substances, which form the largest class of flame retardants other classes are phosphorus-containing, nitrogen-containing, and inorganic flame retardants (Bimbaum and Sttaskal 2004). The major BFR substances in use today (depicted in Fig. 4.6) are tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and mixtures of polybrominated diphenyl ethers (PBDEs) (namely, deca-bromodiphenyl ether (DBDE), octabromodiphenyl ether (OBDE), and pentabro-modiphenyl ether (pentaBDE)). 

The RoHS procedure has now combined with European Union Registration, Evaluation, Authorisation and restriction of Chemicals (REACH), which is a new European Union Regulation (EC/2006/1907 of 18 December 2006). Four additional substances are listed that will be assessed as a priority, among these substances is hexabromocyclododecane, a brominated flame retardant widely used in expanded polystyrene for which no alternatives have been found so far. REACH addresses the production and use of chemical substances and their potential impacts on both human health and the environment it has been described as the most complex legislation in the Union s history and the most important in the last 20 years. It is the strictest law to date regulating chemical substances and will impact industries throughout the world. REACH entered into force in June 2007, with a phased implementation over the next decade. 

Admon, S., Davis, J. W., Gonsior, S. J., Friederich, U., Hunziker, R. W., Ariano, J. M., Weiss, M. (2007) Environmental fate of hexabromocyclododecane (HBCD), the degradation pathway. In Proceedings of the 4th International Workshop on Brominated Flame Retardants, Amsterdam, The Netherlands, 24-27 April 2007 (unpaginated). 

Brominated flame retardants (BFRs) are a structurally diverse group of compounds including aromatics, cyclic aliphatics, phenolic derivatives, ahphatics, and phthahc anhydride derivatives (Figure 31.3). The most common BFRs are tetrabromobisphenol A (TBBPA), polybrominated diphenyl ethers (PBDE), hexabromocyclododecane (HBCD), and polybrominated biphenyls (PBB). The primary use of TBBPA is as reactive additive in epoxy resin circuit boards, while decabromodiphenyloxide (DBDO) is primarily used in high impact polystyrene for electronic enclosures. PBDEs are typically used as the additive type of flame retardant in high impact polystyrene, acrylonitrile butadiene styrene, flexible polyurethane foam, textile coatings, wire and cable insulation and electrical connectors. 

Brominated flame retardants can be divided into three main groups polybrominated diphenyl ethers (PBDE), hexabromocyclododecane (HBCD) and tetrabromobisphenol-A (TBBPA), which is by far the most widely produced and used of all the brominated flame retardants. 

Eor almost 40 years, the brominated flame retardants (BERs) polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and tetrabro-mobisphenol-A (TBBPA) have been widely used as additive or reactive flame retardants (ERs) in household products and food packaging to meet flammability standards. These chemicals are now recognized as global contaminants and are associated with adverse health effects in animals and humans. 

Abdallah MA-E, Harrad SJ, Ibarra C et al (2008b) Hexabromocyclododecanes in indoor dust from Canada, the United Kingdom, and the United States. Environ Sci Technol 42 459-464 Akutsu K, Takatori S, Nozawa S et al (2008) Polybrominated diphenyl ethers in human serum and sperm quality. B Environ Contam Tox 80 345-350 Alaee M, Arias P, Sjodin A et al (2003) An overview of commercially used brominated flame retardants, their applications, their use patterns in different countries/regions and possible modes of release. Environ Int 29 683-689... 

Ema M, Fujii S, Hirata-Koizumi M et al (2007) Two-generation reproductive toxicity study of the flame retardant hexabromocyclododecane in rats. Reprod Toxicol 25 335-351 Eriksson P, Fischer C, Fredriksson A (2006) Poly-brominated diphenyl ethers, a group of brominated flame retardants, can interact with polychlorinated biphenyls in enhancing developmental neurobehavioral defects. Toxicol Sci 94 302-309 Eskenazi B, Chevrier J, Rauch SA et al (2013) In utero and childhood polybrominated diphenyl ether (PBDE) exposures and neurodevelopment in the CHAMACOS study. Environ Health Perspect 121 257-261... 

Tue NM, Takahashi S, Suzuki G et al (2013) Contamination of indoor dust and air by polychlorinated biphenyls and brominated flame retardants and relevance of non-dietary exposure in Vietnamese informal e-waste recycling sites. Environ Int 51 160-167 United Nations Environment Programme (UNEP) (2013) Recommendation by the persistent organic pollutants review committee to list hexabromocyclododecane in annex A to the Stockholm convention and draft text of the proposed amendment. Conference of the parties to the Stockholm convention on persistent organic pollutants sixth meeting, Geneva, Switzerland (28 April-10 May 2013)... 

BFRs are one of the last classes of halogenated compounds that are still being produced worldwide and used in high quantities in many applications. In order to meet fire safety regulations, flame retardants (FRs) are applied to combustible materials such as polymers, plastics, wood, paper, and textiles. Approximately 25% of all FRs contain bromine as the active ingredient. More than 80 different aliphatic, cyclo-aliphatic, aromatic, and polymeric compounds are used as BFRs. BFRs, such as polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA), have been used in different consumer products in large quantities, and consequently they were detected in the environment, biota, and even in human samples [26, 27]. 

Another approach to durable flame retardant finishes for polyester is the use of highly brominated chemicals as topical finishes. One particularly useful material is hexabromocyclododecane (HBCD, Fig. 8.19). To achieve durable flame retardancy, fabric padded with 8 % of a dispersion of this water insoluble material must be heated above 190 °C or 375 °F to form a film of the flame retardant on the fibre surface."... 

Tribromophenylallyl ether FR-913. Aromatic flame retardant for expandable PS synergist with hexabromocyclododecane. White to off-white crystal powder mp = 74-76" d = 2.20 LD50 (rat orl) > 5000 mg/kg (rbt der) > 2000 mg/kg. AmeriBrom Inc. Amerihaas Dead Sea Bromine. 

Uses Flame retardant for PS, latex, textiles organic synthesis Manuf./Distiib. AmeriBrom http //www.amerlbrom.com. Ocean Chems. http //WWW. oceanchemicals. co. uk Trade Name Synonyms FR-1206 [AmeriBrom http //www.amerlbrom.com. Dead Sea Bromine http //WWW. dsbg. com] 1,2,5,6,9,10-Hexabromocyclododecane CAS 3194-55-6 EINECS/ELINCS 221-695-9 Synonyms Cyclododecane, 1,2,5,6,9,10-hexabromo-Empirical Ci2HisBr6... 

In the past, polyethylenes were generally flame-retarded with chloroparaffins and antimony trioxide. Frequently PVC or chlorinated polyethylene was also added. Nowadays cycloaliphatic (hexabromocyclododecane) and aromatic bromine compoimds such as polybromodiphenyl ethers, and in particular decabromodiphenyl ether are used. Antimony trioxide is also used here as a synergist. 

Today there are more than 75 different types of these substances, the classic examples of which include brominated biphenyls, diphenyl ethers, cyclododecane and bisphenol A. The use of individual flame retardants depends on the type of polymer, use of the product, its durability and the desired aesthetic appearance. The most commonly used BFRs are mixtures of polybrominated diphenyl ethers (PBDEs, 12-133), 2,2, 6,6 -tetrabromobisphenol A (TBBPA, 12-134) and 1,2,5,6,9,10-hexabromocyclododecane (HBCD or HBCDD, 12-135), but the regular classic BFRs are still polybrominated biphenyls (PBB, 12-136). 

The synthesis of hexabromocyclododecane is shown in Figure 7.1. Hexabromocyclododecane is obtained by the trimerization of 1,3-butadiene followed by bromination. It is the most important flame retardant for foamed poly (styrene). In addition, sulfonic salt based flame retardants are shown in Table 7.3. 

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