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'.
[edit] Related articles on Designing Buildings
- Adhesives.
- Asbestos.
- Binding agent.
- Construction dust.
- Construction materials.
- Contaminated land.
- Control of Substances Hazardous to Health.
- Deleterious materials.
- Environmental legislation.
- Environmental policy.
- Hazardous substances.
- Inspections focus on occupational lung disease.
- Planning (Hazardous Substances) Act 1990.
- Persistent organic pollutants (POP).
- Ozone depleting substances.
- Pollution.
- Structural adhesives.
- Types of materials.
- Types of rigid foam insulation.
- Volatile organic compounds VOC.
- Workplace exposure limits.
Featured articles and news
Experimental AI housing target help for councils
Experimental AI could help councils meet housing targets by digitising records.
Gregor Harvie argues that AI is state-sanctioned theft of IP.
Preserving, waterproofing and decorating buildings.
Many resources for visitors aswell as new features for members.
Using technology to empower communities
The Community data platform; capturing the DNA of a place and fostering participation, for better design.
Heat pump and wind turbine sound calculations for PDRs
MCS publish updated sound calculation standards for permitted development installations.
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Heritage staff wellbeing at work survey.
A five minute introduction.
50th Golden anniversary ECA Edmundson apprentice award
Showcasing the very best electrotechnical and engineering services for half a century.
Welsh government consults on HRBs and reg changes
Seeking feedback on a new regulatory regime and a broad range of issues.