Names | |
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Preferred IUPAC name 1,2,5,6,9,10-Hexabromocyclododecane | |
Other names Hexabromocyclododecane | |
Identifiers | |
3D model (JSmol) | |
Abbreviations | HBCDD HBCD |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.019.724 |
EC Number |
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PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C12H18Br6 | |
Molar mass | 641.7 g/mol |
Melting point | 186 °C (367 °F; 459 K) (175–195 °C, depending upon isomer) |
3.4 µg/L in water | |
Hazards | |
GHS labelling: | |
Warning | |
H315, H319, H335, H361, H362, H410 | |
P201, P202, P260, P261, P263, P264, P270, P271, P273, P280, P281, P302+P352, P304+P340, P305+P351+P338, P308+P313, P312, P321, P332+P313, P337+P313, P362, P391, P403+P233, P405, P501 | |
NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Hexabromocyclododecane (HBCD or HBCDD) is a brominated flame retardant. It consists of twelve carbon, eighteen hydrogen, and six bromine atoms tied to the ring. Its primary application is in extruded (XPS) and expanded (EPS) polystyrene foam used as thermal insulation in construction. Other uses are upholstered furniture, automobile interior textiles, car cushions and insulation blocks in trucks, packaging material, video cassette recorder housing, and electric and electronic equipment. According to UNEP, "HBCD is produced in China, Europe, Japan, and the USA. The known current annual production is approximately 28,000 tonnes per year. The main share of the market volume is used in Europe and China" (figures from 2009 to 2010). [2] Due to its persistence, toxicity, and ecotoxicity, the Stockholm Convention on Persistent Organic Pollutants decided in May 2013 to list hexabromocyclododecane in Annex A to the convention with specific exemptions for production and use in expanded polystyrene and extruded polystyrene in buildings. Because HBCD has 16 possible stereo-isomers with different biological activities, the substance poses a difficult problem for manufacture and regulation.
HBCD's toxicity and its harm to the environment are current sources of concern. HBCD can be found in environmental samples such as birds, mammals, fish, and other aquatic organisms as well as soil and sediment. [3] On this basis, on 28 October 2008, the European Chemicals Agency decided to include HBCD in the SVHC list, [4] Substances of Very High Concern, within the Registration, Evaluation, Authorisation and Restriction of Chemicals framework. On 18 February 2011, HBCD was listed in Annex XIV of REACH and hence is subject to Authorisation. HBCD can be used until the so-called “sunset date” (21 August 2015). After that date, only authorized applications will be allowed in the EU.
HBCD has been found widely present in biological samples from remote areas and supporting pieces of evidence for its classification as Persistent, Bioaccumulative, and Toxic (PBT) and undergoes long-range environmental transportation. [5] In July 2012, an EU-harmonized classification and labeling for HBCD entered into force. HBCD has been classified as a category 2 for reproductive toxicity. [6] Since August 2010 hexabromocyclododecanes are included in the EPA's List of Chemicals of Concern. [7] In May 2013 the Stockholm Convention on Persistent Organic Pollutants (POPs) decided to include HBCD in the convention's Annex A for elimination, with specific exemptions for expanded and extruded polystyrene in buildings needed to give countries time to phase-in safer substitutes. HBCD is listed for elimination, but with a specific exemption for expanded polystyrene (EPS) and extruded polystyrene (XPS) in buildings. Countries may choose to use this exemption for up to five years after the request for exemption is submitted. [8] Japan was the first country to implement a ban on the import and production of HBCD effective in May 2014.
Because HBCD has 16 possible stereo-isomers with different biological activities, the substance poses a difficult problem for manufacture and regulation. [9] The HBCD commercial mixture is composed of three main diastereomers denoted as alpha (α-HBCD), beta (β-HBCD), and gamma (γ-HBCD) with traces of others. A series of four published in vivo mice studies were conducted between several federal and academic institutions to characterize the toxicokinetic profiles of individual HBCD stereoisomers. The predominant diastereomer in the HBCD mixture, γ-HBCD, undergoes rapid hepatic metabolism, fecal and urinary elimination, and biological conversion to other diastereomers with a short biological half-life of 1–4 days. After oral exposure to the γ-HBCD diastereomer, β-HBCD was detected in the liver and brain, and α-HBCD and β-HBCD was detected in the fat and feces [10] with multiple novel metabolites identified - monohydroxy-pentabromocyclododecane, monohydroxy-pentabromocyclododecene, dihydroxy-pentabromocyclododecene, and dihydroxy-pentabromocyclododecadiene. [11] In contrast, α-HBCD is more biologically persistent, resistant to metabolism, bioaccumulates in lipid-rich tissues after a 10-day repeated exposure study, and has a longer biological half-life of up to 21 days; only α-HBCD was detected in the liver, brain, fat and feces with no stereoisomerization to γ-HBCD or β-HBCD and low trace levels of four different hydroxylated metabolites were identified. [12] Developing mice had higher HBCD tissue levels than adult mice after exposure to either α-HBCD or γ-HBCD indicating the potential for increased susceptibility of the developing young to HBCD effects. [13] The reported toxicokinetic differences of individual HBCD diastereoisomers have important implications for the extrapolation of toxicological studies of the commercial HBCD mixture to the assessment of human risk.
This section needs to be updated.(January 2020) |
Due to its persistence, toxicity, and ecotoxicity, the Stockholm Convention on Persistent Organic Pollutants decided in May 2013 to list hexabromocyclododecane in Annex A to the convention with specific exemptions for production and use in expanded polystyrene and extruded polystyrene in buildings. Countries may choose to use this exemption for up to five years after the request for exemption is submitted. [14]
There is a large and still increasing stock of HBCD in the anthroposphere, mainly in EPS and XPS insulation boards. [15] A long-term environmental monitoring program run by the Fraunhofer Institute for Molecular Biology and Applied Ecology demonstrates a general trend that HBCD concentrations are decreasing over time. [16] HBCD emissions into the environment are controlled under the voluntary industry emission management program: the Voluntary Emissions Control Action Programme (VECAP). [17] The VECAP annual report demonstrates a continuous decrease of potential emissions of HBCD to the environment. [18]
Borax (also referred to as sodium borate, tincal and tincar ) is a salt (ionic compound), a hydrated or anhydrous borate of sodium, with the chemical formula Na2H20B4O17 (also written as Na2B4O7·10H2O).
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a poor barrier to air and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics, with the scale of its production being several million tonnes per year. Polystyrene is naturally transparent, but can be colored with colorants. Uses include protective packaging, containers, lids, bottles, trays, tumblers, disposable cutlery, in the making of models, and as an alternative material for phonograph records.
Lindane, also known as gamma-hexachlorocyclohexane (γ-HCH), gammaxene, Gammallin and benzene hexachloride (BHC), is an organochlorine chemical and an isomer of hexachlorocyclohexane that has been used both as an agricultural insecticide and as a pharmaceutical treatment for lice and scabies.
Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles. They are structurally akin to polychlorinated diphenyl ethers (PCDEs), polychlorinated biphenyls (PCBs) and other polyhalogenated compounds, consisting of two halogenated aromatic rings. PBDEs are classified according to the average number of bromine atoms in the molecule. The life-saving benefits of fire retardants led to their popularization. Standards for mass transit vehicles continues to increase as of 2021.
Flame retardants are a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an ignition source and prevent or slow the further development of flames by a variety of different physical and chemical mechanisms. They may be added as a copolymer during the polymerisation process, or later added to the polymer at a moulding or extrusion process or applied as a topical finish. Mineral flame retardants are typically additive, while organohalogen and organophosphorus compounds can be either reactive or additive.
Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed on 22 May 2001 in Stockholm and effective from 17 May 2004, that aims to eliminate or restrict the production and use of persistent organic pollutants (POPs).
Toxicokinetics is the description of both what rate a chemical will enter the body and what occurs to excrete and metabolize the compound once it is in the body.
Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) is a European Union regulation dating from 18 December 2006. REACH addresses the production and use of chemical substances, and their potential impacts on both human health and the environment. Its 849 pages took seven years to pass, and it has been described as the most complex legislation in the Union's history and the most important in 20 years. It is the strictest law to date regulating chemical substances and will affect industries throughout the world. REACH entered into force on 1 June 2007, with a phased implementation over the next decade. The regulation also established the European Chemicals Agency, which manages the technical, scientific and administrative aspects of REACH.
Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released.
Brominated flame retardants (BFRs) are organobromine compounds that have an inhibitory effect on combustion chemistry and tend to reduce the flammability of products containing them. The brominated variety of commercialized chemical flame retardants comprise approximately 19.7% of the market. They are effective in plastics and textile applications like electronics, clothes, and furniture.
β-Hexachlorocyclohexane (β-HCH) is an organochloride which is one of the isomers of hexachlorocyclohexane (HCH). It is a byproduct of the production of the insecticide lindane (γ-HCH). It is typically constitutes 5–14% of technical-grade lindane, though it has not been produced or used in the United States since 1985. As of 2009, the Stockholm Convention on Persistent Organic Pollutants classified α-hexachlorocyclohexane and β-HCH as persistent organic pollutants (POPs), due to the chemical's ability to persist in the environment, bioaccumulative, biomagnifying, and long-range transport capacity.
Decamethylcyclopentasiloxane, also known as D5 and D5, is an organosilicon compound with the formula [(CH3)2SiO]5. It is a colorless and odorless liquid that is slightly volatile.
Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes. The chlorination degree of CPs can vary between 30 and 70 wt%. CPs are subdivided according to their carbon chain length into short-chain CPs, medium-chain CPs and long-chain CPs. Depending on chain length and chlorine content, CPs are colorless or yellowish liquids or solids.
Decabromodiphenyl ether is a brominated flame retardant which belongs to the group of polybrominated diphenyl ethers (PBDEs). It was commercialised in the 1970s and was initially thought to be safe, but is now recognised as a hazardous and persistent pollutant. It was added to Annex A of the Stockholm Convention on Persistent Organic Pollutants in 2017, which means that treaty members must take measures to eliminate its production and use. The plastics industry started switching to decabromodiphenyl ethane as an alternative in the 1990s, but this is now also coming under regulatory pressure due to concerns over human health.
Octabromodiphenyl ether is a brominated flame retardant which belongs to the group of polybrominated diphenyl ethers (PBDEs).
Tetrabromobisphenol A (TBBPA) is a brominated flame retardant. The compound is a white solid, although commercial samples appear yellow. It is one of the most common flame retardants.
Triphenyl phosphate (TPhP) is the chemical compound with the formula OP(OC6H5)3. It is the simplest aromatic organophosphate. This colourless solid is the ester (triester) of phosphoric acid and phenol. It is used as a plasticizer and a fire retardant in a wide variety of settings and products.
Dechlorane plus is a polychlorinated flame retardant produced by Oxychem.
α-Hexachlorocyclohexane (α-HCH) is an organochloride which is one of the isomers of hexachlorocyclohexane (HCH). It is a byproduct of the production of the insecticide lindane (γ-HCH) and it is typically still contained in commercial grade lindane used as insecticide. Lindane, however, has not been produced or used in the United States for more than 20 years. At ambient temperatures it is a stable, white, powdery solid substance. As of 2009, the Stockholm Convention on Persistent Organic Pollutants classified (α-HCH) and (β-HCH) as persistent organic pollutants (POPs), due to the chemical's ability to persistence in the environment, bioaccumulative, biomagnifying, and long-range transport capacity.
Bis(2-ethylhexyl)tetrabromophthalate (or TBPH), is a brominated phthalate derivative with the formula C24H34Br4O4 commonly used as a brominated flame retardant (BFR).