Hexabromocyclododecane

HBCD; HBCDD; 1,2,5,6,9,10-Hexabromocyclododecane; formula: C12H18Br6; CAS Registry Number: 3194-55-6
Structure of HBCD
Source: GSBL Joint Substance Database

Brominated flame retardant in polystyrene foams and other plastics

Hexabromocyclododecane (HBCD) is a very effective flame retardant. It is mainly used in expanded and extruded polystyrene foams (EPS and XPS) which are used as thermal insulation foams in the construction sector. Furthermore, HBCD is applied in HIPS (high impact polystyrene) used for instance in the housing of electrical and electronic devices and in back-coating of textiles, e.g. in upholstery and car textiles.
As additive flame retardant HBCD it is not chemically bound to the plastic matrix.

Sixteen different stereoisomers of HBCD exist but only the diastereomers α-HBCD, β-HBCD, and γ-HBCD are found in relevant amounts in technical HBCD. Each of these are pairs of enatiomers (mirror images of each other), designated as (+) and (-).

HBCD enters the environment mainly through releases from textile coatings whereas releases during production and from polystyrene foams and HIPS are assumed to be relatively low.
Traces of HBCD are detected in all environmental compartments. Through long range transport it even reaches remote areas like alpine lakes.
HBCD is relative persistent in the environment and toxic to aquatic organisms. Furthermore, it has a very high potential for bioaccumulation and biomagnification.
Because of these properties it was classified as SVHC (substance of very high concern) in the context of the REACh evaluation (Registration, Evaluation, Authorisation and Restriction of Chemicals). Furthermore, it is a candidate for listing under the Stockholm Convention.

However, so far no alternative to HBCD in its major applications exists. Therefore HBCD is used further despite its unfavourable properties.

Substances

alpha-HBCD Sum of (+)- und (-)-α-HBCD (pair of enantiomers). Minor component of technical HBCD (1–12%). In biota the levels of α-HBCD are normally much higher compared to those of β- und γ-HBCD.

Specimen

Herring gull Inshore, the herring gull mainly feeds from the sea: upon fish, mussels, and crabs.

Sampling area

NP Vorpommersche Boddenlandschaft National Park in the largest brackish water (Bodden) habitat of the world.
BR/NP Wattenmeere National park in the world largest connected sand and mud flats.

Sampling period

1988 - 2008