EPA’s Design for the Environment (DfE) office has issued a report that offers three alternatives to hexabromocyclododecane (HBCD), a flame retardant that has been extensively used in expanded and extruded polystyrene foam (EPS and XPS), a popular building insulation material.
According to the EPA, HBCD is highly hazardous to aquatic species and also poses moderate neurological and carcinogenic risks to people. Each of the assessed alternatives ranks low in risks to aquatic organisms, but only one—butadiene styrene brominated copolymer—was found to pose low risks to humans.
The EPA states that the assessment was conducted with the participation of stakeholders. At least one major chemical manufacturer, Dow Chemical Company, has committed to developing feasible and less hazardous replacements for HBCD.
REACH prohibition
According to information in EPA’s Toxic Substances Control Act (TSCA) inventory, between 10 and 50 million pounds of HBCD were manufactured or imported in the United States in 2005.
In the most recent TSCA reporting for 2011, now called Chemical Data Reporting (CDR), the volume of HBCD manufactured or imported in the U.S. was claimed confidential and could not be described in the DfE report. More recent information reported by the European Chemicals Agency in 2009 shows that in 2006 to 2007, 96 percent of HBCD was used in EPS and XPS foam.
The use of HBCD as a flame retardant will be banned as of August 21, 2015, under the European Union’s Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) legislation unless it is expressly authorized for an applicant.
Environmental persistence
The DfE report found that butadiene styrene brominated copolymer offers multiple human health and environmental benefits over HBCD.
“Due to its large size, lack of low molecular weight (MW) components, and un-reactive functional groups, human health and ecotoxicity hazard for this polymer are measured or predicted to be low, although experimental data were not available for all endpoints,” says the EPA.
The Agency adds that this alternative is persistent in the environment, a characteristic that is common to all flame retardants. Chemical suppliers have commercialized this polymer, says the EPA, and polystyrene manufacturers are testing it in their products to ensure that the polystyrene will meet all performance standards.
The two other alternatives described in the report are tetrabromobisphenol A (TBBPA)-bis brominated ether derivative and TBBPA bis(2,3-dibromopropyl) ether. Both substances were found to pose lower risks to aquatic species than HBCD, but the human health effects were found to be more deleterious than those of butadiene styrene brominated copolymer and about equal to those of HBCD.
Other options
In addition to the chemical hazard assessment of HBCD and its alternatives, the report includes general information about alternative insulation materials. These technologies include rigid board (e.g., similar to EPS and XPS), alternatives for certain functional uses (e.g., blanket insulation, foamed-in-place insulation), and specialty and emerging alternative materials (e.g., aerogel, carbon foam). The report does not assess these materials, does not compare them to EPS or XPS, and does not assess flame retardancy needs for each of these materials.
DfE report