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
What it is and how to use it.
Investors in People: CIOB achieves gold
Reflecting a commitment to employees and members.
Scratching beneath the surface; a guide to selection.
ECA 2024 Apprentice of the Year Award
Entries open for submission until May 31.
UK gov apprenticeship funding from April 2024
Brief summary the policy paper updated in March.
For the World Autism Awareness Month of April.
70+ experts appointed to public sector fire safety framework
The Fire Safety (FS2) Framework from LHC Procurement.
Project and programme management codes of practice
CIOB publications for built environment professionals.
The ECA Industry Awards 2024 now open !
Recognising the best in the electrotechnical industry.
Sustainable development concepts decade by decade.
The regenerative structural engineer
A call for design that will repair the natural world.
Buildings that mimic the restorative aspects found in nature.
CIAT publishes Principal Designer Competency Framework
For those considering applying for registration as a PD.
BSRIA Building Reg's guidance: The second staircase
An overview focusing on aspects which most affect the building services industry.
Design codes and pattern books
Harmonious proportions and golden sections.
Introducing or next Guest Editor Arun Baybars
Practising architect and design panel review member.