Hexabromocyclododecane (HBCD)

This fact sheet is a summary of the Priority Existing Chemical (PEC) report at the time it was assessed and published.

CAS No: 25637-99-4

Hexabromocyclododecane (HBCD) is one of a group of polybrominated flame retardants, or PBFRs.  It is used in expandable polystyrene foams in domestic and industrial building insulation, packaging of industrial products and bean bag fills. Other uses are as a polypropylene resin in housings for domestic electrical appliances and as a textile coating additive in blinds, baby car seats, public seating and textiles.

Finished articles containing HBCD include extruded polystyrene (XPS) boards, office equipment such as inkjet printers, projectors, scanners and ceiling ventilator covers.

Background

In 2001, because of concerns of widespread use of flame retardants in households and industry, the National Industrial Chemicals Notification and Assessment Scheme (NICNAS) assessed the extent of use of PBFRs in Australia and recommended that a full risk assessment be made, once testing of the chemicals was completed internationally.

Another survey by NICNAS in October 2004 indicated a significant increase in the use of HBCD in Australia compared to the period 1998-99.

The decision to conduct a risk assessment of HBCD as a Priority Existing Chemical in 2005 was based on:

  • Use of HBCD as a flame retardant in polyester foam in domestic and industrial building insulation and in polystyrene beads used in insulation of articles such as housing for domestic electrical appliances and baby car seats. It is also used in other styrene resins, latex binders, unsaturated polyesters and textile coatings.
  • Adverse effects from exposure to HBCD, such as increase in liver weights and thyroid-related hyperplasia, and effects on reproductive parameters. Emerging evidence indicated that HBCD was persistent in the atmosphere and had adverse effects on the environment.

Manufacture and import

HBCD is not manufactured in Australia, but is imported in expandable polystyrene (EPS) resin, as liquid dispersions and as a component of the plastic in finished articles. NICNAS's assessment showed a decrease in the import of HBCD over recent years, with approximately 90 tonnes imported in 2006-07 and about 60 tonnes in 2009-10.  Import into Australia of HBCD as powder or granules ceased in 2010.

Health effects

Animal studies indicate that HBCD is rapidly absorbed and excreted (within 72 hours) after oral exposure. Tissue distribution is widespread with the highest concentrations found in fat tissue and muscle followed by the liver, lung, kidney, blood and brain.

HBCD has low acute toxicity via all routes, low eye and skin irritation and sensitising potential in rodents. It is also not a skin sensitiser in humans.

Available data do not support a genotoxic or carcinogenic potential for HBCD. However, there are reports of increased liver, thyroid and pituitary weights in rats exposed repeatedly to HBCD.

HBCD shows no marked adverse effects on fertility parameters. It has developmental effects in rats such as low pup weights and increased mortality following exposure to HBCD through milk.

Public exposure and health risk

Consumers using treated products (e.g. automotive upholstery) may be exposed to HBCD that diffuses out of the articles. Estimates of dermal exposure (main route) from this source indicate very low exposure and therefore low risk to adults as well as children.

Indirect exposure to HBCD through the environment may occur by consumption of food and drinking water contaminated by HBCD and by inhalation of indoor and outdoor air. Exposure to HBCD from these sources appears to be low and hence low risk is expected.

Toddlers may have the highest exposure to HBCD through ingestion and inhalation of dust/soil containing HBCD released from HBCD containing articles in the house, however, the risk of developing adverse health effects is low. The risk to infants through exposure to HBCD in breast milk is also estimated to be low.

Occupational exposure and health risk

Exposure of workers to HBCD depends on the form of HBCD used, powder or granular forms or aqueous solution, the nature of the work, and the different use patterns.

Workers  treating textiles with HBCD products or engaged in the manufacture and cutting of HBCD-treated EPS boards  may be exposed to HBCD. The risk to workers of acute adverse health effects such as inhalation toxicity, skin, eye and respiratory irritation and skin sensitisation is low. However, the risk of chronic harmful effects from exposure during these processes is high in a reasonable worst-case scenario.

Environmental effects, exposure and risk

Available evidence indicates that HBCD is persistent and bioaccumulative and toxic, especially to aquatic organisms. It  meets the criteria for persistence, bioaccumulation and toxicity of the Stockholm Convention on Persistent Organic Pollutants POPs.

Calculating 'safe' concentrations for compounds such as HBCD that are persistent in the environment, bioaccumulate and also biomagnify in the food chain is difficult because potential adverse effects may not become evident for very long periods of time.

Assessment outcomes

The greatest risks are to the environment and workers handling HBCD, thus both need to be managed.

NICNAS has made a series of recommendations for suitable management to relevant authorities, and to importers and formulators of HBCD and HBCD products. Implicit in these recommendations is that best practice is implemented to minimise occupational and public exposure and environmental impact.

Recommendations

The report contains three main recommendations.

  • The hazard classification (Toxic to reproduction) to be included in the Hazardous Substances Information System (HSIS) and suppliers and employers to note the hazard classification and the dangerous goods classification and amend (Material) Safety Data Sheets and labels accordingly.
  • Manufacturers and importers of HBCD and flame retarded articles should move away from the import and use of HBCD chemical, and articles containing the chemical, in applications where safer alternatives and technologies are commercially available.
  • The Standing Council on Environment and Water, that provides advice to state and territory environmental agencies, develop an action plan to address the currently unacceptable risk to the environment arising from the use of HBCD and products containing HBCD.

Current status

The HSIS includes the recommended  hazard classification of HBCD as follows:

  • Toxic to reproduction, Category 3, with the following risk phrases:
    • R63 Possible risk of harm to the unborn child (Toxic to reproduction, Category 3).
    • R64 May cause harm to breastfed babies.

The full NICNAS Priority Existing Chemical report on HBCD is available on the NICNAS website.

Please note, our recommendations are not always implemented by chemical regulators. For the most up-to-date information about how a particular chemical is regulated in your State or Territory you will need to contact other government agencies. Read What we do for details about our regulatory partners.

Last update 1 May 2013