K0952237 160709 

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SC 

UNEP/POPS/POPRC.5/4

Stockholm Convention 

on Persistent Organic 

Pollutants 

Distr.: General 

9 July 2009 

Original: English

Persistent Organic Pollutants Review Committee 

Fifth meeting 

Geneva, 12–16 October 2009 

Item 6 (a) of the provisional agenda* 

Consideration of chemicals proposed for inclusion in annexes 

A, B or C of the Convention: hexabromocyclododecane 

Summary of a proposal to list hexabromocyclododecane in 

Annex A to the Convention1

Note by the Secretariat 

1. The listing of new chemicals in Annexes A, B or C of the Stockholm Convention is governed by 

Article 8 of the Convention. Paragraph 1 of Article 8 provides that a Party may submit a proposal to list 

a chemical in those annexes and that the proposal should contain the information specified in Annex D 

of the Convention. Paragraph 2 of Article 8 provides that the Secretariat shall verify whether the 

proposal contains the information specified in Annex D and, if it does, forward it to the Persistent 

Organic Pollutants Review Committee. 

2. The annex to the present note contains a summary of a proposal submitted by Norway to list 

hexabromocyclododecane in Annex A of the Convention pursuant to paragraph 1 of Article 8 of the 

Convention.2

 The summary is being circulated as prepared by Norway and has not been formally edited. 

A copy of the complete proposal is set out in document UNEP/POPS/POPRC.5/INF/16. The 

Secretariat's conclusion regarding whether the proposal contains the information specified in Annex D 

is discussed in document UNEP/POPS/POPRC.5/INF/15. 

Possible action by the Committee 

3. The Committee may wish: 

(a) To consider the information provided in the present note and in document 

UNEP/POPS/POPRC.5/INF/16; 

 

* UNEP/POPS/POPRC.5/1.

1 Mandate for the action described in the present note contained in: Stockholm Convention, Article 8, 

paragraph 1. 

2 The proposal was submitted by Norway on 19 June 2008, prior to the fourth meeting of the Committee. 

Following discussion of the proposal at that meeting in plenary sessions and in a contact group, the Committee 

decided to continue its consideration of it at the current meeting. The Committee's treatment of the proposal at its 

fourth meeting is described in paragraphs 102–109 of the report of that meeting (UNEP/POPS/POPRC.4/15). 
UNEP/POPS/POPRC.5/4 

2 

(b) To decide whether it is satisfied that the proposal fulfils the requirements of Article 8 

and Annex D of the Convention; 

(c) To develop and agree on, if it decides that the proposal fulfils the requirements referred 

to in subparagraph 2 (b) above, a workplan for preparing a draft risk profile pursuant to paragraph 6 of 

Article 8. 
UNEP/POPS/POPRC.5/4 

3

Annex 

Proposal to list hexabromocyclododecane in Annex A of the 

Stockholm Convention on Persistent Organic Pollutants 

Introduction 

1. Commercially available hexabromocyclododecane (HBCDD) is a white solid substance which is 

used as an additive flame retardant on its own, or in combination with other flame retardants. HBCDD 

is used mainly in expanded and extruded polystyrene. Most of this HBCDD-treated polystyrene is used 

for insulation boards in, e.g., buildings and vehicles. Other applications include its use in textile 

coatings and in high impact polystyrene for electrical and electronic equipment. HBCDD is the third 

most used brominated flame retardant and the global market demand in 2001 was 16 700 tonnes. 

Technical HBCDD is a mix of mainly three diastereomers (compounds that are identical except for the 

spatial disposition of the atoms), alpha-, beta-, and gamma-HBCDD, and the final distribution of these 

diastereomers in technical HBCDD varies with a range of about 70-95 % γ-HBCDD and 5-30 % α- and 

β-HBCDD. 

2. Alternative chemicals and techniques for avoiding the use of HBCDD are available for most of 

its uses. European industry has already started voluntary programs to manage the releases from 

industrial sites. 

3. The present dossier and review provided by the proponent3

 focuses solely on the information 

required under paragraphs 1 and 2 of Annex D of the Stockholm Convention and it is mainly based on 

information from the following review reports: 

(a) Risk Assessment Hexabromocyclododecane, CAS-No.: 25637-99-4, EINECS-No.: 247-

148-4, Final draft October 2007. European Commission 2007 (available at 

http://ecb.jrc.it/documentation/). 

(b) Strategy for limiting risks, hexabromocyclododecane (HBCDD), Draft on 4 September 

2007, Swedish Chemical Agency 2007. 

4. These reviews and the document of additional information provided by the proponent (with over 

100 references)2

 also serve as sources of the additional information referred to in paragraph 3 of Annex 

D of the Stockholm Convention on this candidate POP chemical. 

1. Identification of the chemical 

5. Producers and importers have provided information under the European statutory requirements 

under two names with corresponding CAS- and EINECS-numbers. The numbers correlate to the isomer 

composition, and one set of numbers refer to an unspecific isomer composition (all isomers), while the 

other refers to the composition with the three main diastereomers (se below). Both of these substances 

are covered in this dossier. There are no known differences in molecular structure or properties of these 

two substances. Separate CAS-numbers have also been reported for the three diastereomers, but they 

are not accounted for in this dossier. 

 

3 Hexabromocyclododecane as a possible global POP. TemaNord 2008:520. Nordic Council of Ministers, 

Copenhagen 2007. 91 pp. 
UNEP/POPS/POPRC.5/4 

4 

1.1 Names and registry numbers 

IUPAC4

 name: Hexabromocyclododecane 

EINECS5

 name: Hexabromocyclododecane 

CAS6 number: 25637-99-47

EINECS number: 247-148-4 

EINECS name: 1,2,5,6,9,10-Hexabromocyclododecane 

CAS number: 3194-55-68

EINECS number: 221-695-9 

Synonyms: cyclododecane, hexabromo- 

 HBCDD 

Trade names: Bromkal 73-6CD, Nikkafainon CG 1, Pyroguard F 800, Pyroguard SR 103, 

Pyroguard SR 103A, Pyrovatex 3887, Great Lakes CD-75PTM, Great Lakes CD75, Great Lakes CD75XF, Great Lakes CD75PC (compacted), Dead Sea 

Bromine Group Ground FR 1206 I-LM, Dead Sea Bromine Group Standard FR 

1206 I-LM, Dead Sea Bromine Group Compacted FR 1206 I-CM 

1.2 Structure 

Chemical structure: 

Molecular formula: C12H18Br6

Molecular weight: 641.7 

2. Persistence 

6. Photochemical degradation half-life of HBCDD in the atmosphere is estimated by AopWin 

v1.91 to be 76.8 hours (3.2 days). Hydrolysis can be assumed to be an insignificant degradation route 

for HBCDD due to its very low water solubility (66 μg/l for the sum of three diastereomers). 

Theoretically abiotic degradation of HBCDD is possible. According to Kirk-Othmer (1993), HBCDD is 

rather easily dehydrobrominated and has a lower thermo-stability than aromatic brominated flame 

retardants. In practice abiotic degradation is probably of low significance because of the rather rigid 

ring-structure of HBCDD and its low water solubility. 

7. The degradation of HBCDD was studied in a Closed Bottle Test carried out in accordance with 

OECD Guideline 301D and GLP (Schaefer and Haberlein, 1996). According to this study, HBCDD is 

not readily biodegradable and no biodegradation was observed during 28-days at a test concentration of 

7.7 mg HBCDD/l. In the degradation simulation tests with sediment (Davis et al., 2004), (α+β+γ)-

HBCDD was observed to be subject to primary degradation with half-lives of 66 and 101 days in 

anaerobic and aerobic sediment at 20 °C, respectively. These half-lives corresponded with 125 and 191 

days, after a temperature correction to 12 °C was made. Degradation half-lives in aerobic sediment 

were calculated at 20 °C to be 113, 68 and 104 days for α-, β- and γ-HBCDD, respectively. The 

temperature corrected values at 12 °C were 214, 129 and 197 days. Based on the investigations of Davis 

et al. (2004) and Gerecke et al. (2006), α-HBCDD seems to be subject to a slower degradation than 

 

4 International Union of Pure and Applied Chemistry. 

5 European Inventory of Existing Chemical Substances. 

6 Chemical Abstract Service. 

7 This number is more specific in terms of the diastereomeric composition of the substance. 

8 This number refers to an unspecific isomer composition (all isomers). 

Br

Br

Br Br

Br Br
UNEP/POPS/POPRC.5/4 

5

β- and γ-HBCDD. No degradation was observed in the aerobic soil degradation simulation test of Davis 

et al. (2004). 

8. Davis et al. (2004) identified the primary degradation products of HBCDD to be products of a 

stepwise dehalogenation. They observed formation of tetrabromocyclododecane, 

dibromocyclododecadiene and 1,5,9-cyclododecatriene. For this reaction, anaerobic conditions with 

biological activity seemed to be favourable, but dehalogenation was also observed in aerobic and 

abiotic conditions, although with significantly slower disappearance rates of HBCDD. The main 

dehalogenation product, 1,5,9-cyclododecatriene (CDT; CAS 4903-66-4), is not readily biodegradable, 

but based on an enhanced ready biodegradation test modified from OECD 301F the substance was 

observed to be mineralized completely in 63-77 days. 

9. The concentrations measured in the sediment core samples by Christensen et al. (2004), Fjeld et 

al (2006b), Kohler et al. (2006), Remberger et al. (2004) and Sternbeck et al. (2001) provide an 

indication that HBCDD is degraded in sediment more slowly than predicted by the simulation tests. The 

abundance of HBCDD in biota and abiotic samples of remote regions also provides solid evidence of 

the persistency of HBCDD. 

3 Bioaccumulation 

10. The experimental log octanol-water partition coefficient (logKow) value for technical HBCDD 

has been determined to 5.62 (MacGregor and Nixon, 1997), indicating a high potential for 

bioaccumulation. 

11. Bioconcentration for HBCDD in fish has been determined in two reliable flow-through tests, 

and the bioconcentration factors (BCF) were found to be in the range of 8973-21940. Based on both 

studies an overall BCF of 18100 for HBCDD is used in the European Commission Risk Assessment 

(2007). This value well exceeds the limit of 5000 in the screening criteria of Annex D, indicating a high 

potential for bioaccumulation. 

12. In a Lake Ontario (Canada) food web, a trophic magnification factor (TMF) based on δ15N 

relationship of all collected data was estimated to be 6.3 (sum-HBCDD). For the comparison, TMF for 

p,p’DDE and for the sum of PCBs were 6.1 and 5.7 in the same study, respectively. Fjeld (2006a) found 

higher levels of HBCDD in brown trout (Salmo trutta trutta) compared to its prey species European 

smelt (Osmerus eperlanus) and vendace (Coregonus albula). The measured field data from various 

surveys compiled by European Commission (2007) provide additional evidence that HBCDD is 

bioaccumulated in biota in freshwater and marine environments and that the substance is biomagnified 

between trophic levels. 

4 Potential for long-range environmental transport 

13. HBCDD has a vapour pressure of 6.3×10-5 Pa at 21 °C (Stenzel and Nixon, 1997), which 

indicates very low volatility. The substance is slightly volatile from aqueous surfaces based on the 

calculated Henry’s law constant of 0.75 Pa m3

/mol. Atmospheric degradation half-life has, in two 

different models, been estimated to be 76.8 hours and 51.2 hours. Despite its low volatility and very 

high adsorption potential, HBCDD has been found in air samples at concentrations above detection 

limits. 

14. Atmospheric degradation half-life of vapour phase HBCDD varies on both sides of 2 days 

depending on the model settings. Characteristic travel distance (CTD)9

 in air was estimated to be 

approximately 1500 km using ELPOS model. This is approximately in the range of CTDs estimated for 

pentabromodiphenyl ether and other POPs. The half-distances calculated by Ueno et al. (2006) based 

on skipjack tuna monitoring in the North Atlantic seem also to suggest a high potential for long-range 

environmental transport. 

15. HBCDD has been detected in very remote areas, such as in air in northern Sweden and Finland, 

far from potential sources (Bergander et al., 1995; Sternbeck et al., 2001). HBCDD has also been found 

in birds and fish from remote areas, e.g. in liver from Atlantic cod from northern Norway (Fjeld et al., 

2004), in Polar cod and ringed seal from Svalbard in the arctic region (Jensen et al., 2007; Sørmo et al., 

2006), in marine bird and bird eggs from northern Norway (Knudsen et al., 2005; Verreault et al., 2004; 

Gabrielsen et al., 2005), and in polar bears from Svalbard in the Arctic Ocean (Gabrielsen et al., 2004; 

Sørmo et al., 2006). These findings suggest that HBCDD undergoes long-range atmospheric transport. 

 

9 Characteristic travel distance (CTD) = distance at which 37 % of initial mass in air is present. 
UNEP/POPS/POPRC.5/4 

6 

16. HBCDD is ubiquitous in the environment, being also found in remote areas far away from point 

sources (e.g. in polar bears in the arctic). The highest concentrations of HBCDD are detected in marine 

top-predators such as porpoise and seals showing that HBCDD biomagnifies up the food chain. The 

trend also shows an increase in tissue concentrations of HBCDD in biota over time (Stapleton et al., 

2006; Kajiwara et al., 2006b; Isobe et al., 2007a). 

5 Adverse effects 

17. Results from acute and long-term aquatic ecotoxicity studies are available for fish, daphnids and 

algae (freshwater and saltwater). In addition, long-term tests with three sediment organisms, terrestrial 

plants and earthworm are available. Based on the long-term ecotoxicity test with Daphnia magna (28dNOEC 3.1 μg/l; Drottar and Krueger, 1998) and on the growth inhibition test with Skeletonema 

costatum (72h-EC50 52 μg/l; Desjardins et al., 2005), HBCDD is considered very toxic to aquatic 

organisms. In addition, effects were observed in earthworm reproduction rate (NOEC 59 mg/kg dw; 

Aufderheide et al., 2003), but no effects were observed in plants at the highest levels tested (5000 

mg/kg dw; Porch et al., 2002). 

18. According to the available laboratory studies with mammals, HBCDD is not carcinogenic, 

mutagenic or toxic to reproduction (European Commission 2007). HBCDD was observed to cause 

effects in repeated dose studies in liver, thyroid gland and thyroid hormone homeostasis. A NOAEL of 

22.9 mg/kg bw/day for liver weight increase (van der Ven et al., 2006) was the lowest observed 

NOAEL in the available repeated dose studies with oral administration in rats. Furthermore, 

developmental neurotoxicity and changes in sexual organs were observed, but these findings need to be 

confirmed by additional studies including properly designed multi-generation studies. 

6 Statement of the reasons for concern 

19. The proposal of the Government of Norway contains the following statement of concern: 

“HBCDD is highly toxic to aquatic organisms, and according to laboratory tests with mammals, 

it affects the functioning of the thyroid system and liver. There are also indications of effects on 

fertility and developmental neurotoxicity of mammals. HBCDD is according to the available 

data also transferred from mother to child during pregnancy via blood and after delivery via 

breast feeding. 

The monitoring data available from remote areas provide inevitable evidence that HBCDD is 

transported over long distances in the environment. HBCDD has been detected in a number of 

samples in the abiotic environment, biota and/or humans of the Arctic, Europe, Asia and North 

and South America regions. Furthermore, HBCDD is degraded slowly in the aquatic 

environment and soil. It has a great potential for bioaccumulation and in addition there is 

evidence of its biomagnification. The highest concentrations of HBCDD are detected in marine 

top-predators such as porpoise and seals showing that HBCDD biomagnifies up the food chain. 

HBCDD is used as a flame retardant in a wide variety of articles in all parts of the world. The 

releases, as quantified in Europe, are at present entering the environment mainly from a large 

number of industrial point sources. However, HBCDD is also released from articles during and 

at the end of their service-life. In addition, the volume of HBCDD constantly increases in the 

built technosphere (articles in use), and future releases are therefore unpredictable. As HBCDD 

can move far from its sources, single countries or groups of countries alone cannot abate the 

pollution caused by it. Due to the harmful POP properties and risks related to its widespread 

production and use, international action is warranted to control this pollution.” 

____________________