Hexabromocyclododecane HBCD

Hexabromocyclododecane (HBCD) is a synthetic white crystalline chemical compound made up of carbon, hydrogen, and bromine atoms in a ring that is used primarily as a flame retardant. The hexa in the name refers to the presence of six bromine atoms in the molecule which are responsible for its flame-retardant properties.

It has been used in many different commonplace products such as textiles, plastics, electronic equipment.and blown insulation materials such as XPS and EPS, as it helps slow down ignition and spread of flames. In May 2013 the Stockholm Convention on Persistent Organic Pollutants added HBCD to Annex A with specific exemptions for production and use in XPS and EPS in buildings, which countries can apply for a period of up to five years. At the time of writing no exemptions were listed on the Stockholm Convention webpage, with the last expiring in 2021.

It has been classified through various supporting studies as Persistent, Bioaccumulative and Toxic (PBT) meaning a class of chemicals that resist degradation and persist in the environment for long periods. As a result of their persistence, when these chemicals are consumed, they bioaccumulate in the fat tissues, bones, and brain of organisms, it has been detected in air, water, soil, and wildlife. HBCD, has been shown to be oestrogenic, so may also increase the risk of breast cancer in humans, it has been associated with thyroid disorders and is classified as a suspected human reproductive toxicant, meaning it can damage an unborn child.

In the manufacture of textiles chemical alternatives to HBCD include deca-BDE, decabromodiphenyl ethane, ethylene bis(tetrabromophtalimide), chlorinated paraffins and ammonium polyphosphates. Though concerns about deca-BDE have also been listed by the convention. There no specific alternatives for HBCD in the manufacture of XPS or EPS, although research is ongoing, the convention lists alternative approaches to such products without flame retardants such as using thermal barriers, as well as foams such as polyisocyanurate, modified urethane, phenolic and polyurethane a swell as alternative insulative materials..

Many countries have taken steps to phase out or restrict the use of HBCD in many products, particularly construction and insulation materials. In the UK HBCD is listed under the government guidance on using persistent organic pollutants (POPs) and states that 'the manufacture, sale and use of products containing POPs is now banned. You can only use material or products that contain POPs in the specific exceptions to the ban explained in this guide'.

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