HBCD

HBCD, short for hexabromocyclododecane, is a brominated flame retardant used to reduce flammability in polymeric materials. It is most widely applied in polystyrene foams, particularly in building insulation products such as expanded polystyrene (EPS) and extruded polystyrene (XPS), and is also found in textiles, furniture, and some electronic equipment to meet fire-safety standards.

Commercial HBCD is produced as a mixture of stereoisomers, primarily alpha-, beta-, and gamma-HBCD. The different isomers can exhibit distinct chemical behavior and toxicological profiles. In use, HBCD is embedded in the polymer matrix of finished products, where it helps slow the spread of flames without requiring high moisture or heat to activate.

Environmentally, HBCD is persistent and has the potential to bioaccumulate. It can be released from treated products during manufacture, use, and end-of-life processing, entering air, dust, soil, water, and biota. It has been detected in environmental compartments and in wildlife, including marine and terrestrial species, and can undergo long-range environmental transport.

Health and exposure considerations focus on occupational exposure during handling and recycling, as well as consumer exposure via dust and indoor air from treated products. Some studies indicate possible neurodevelopmental and thyroid-related effects, with risk dependent on dose, exposure route, and isomer.

Regulatory status includes regulation under the Stockholm Convention on Persistent Organic Pollutants, reflecting concerns about persistence and bioaccumulation. In many regions, HBCD use is restricted or phased out under REACH or national programs, with a shift toward alternative flame retardants and polymer formulations.