Multinational manufacturers Dow, Owens Corning and Kingspan have phased out halogenated flame retardant hexabromocyclododecane (HBCD) from their building insulation products.
HBCD has been commonly used in expanded and extruded polystyrene (EPS and XPS) foam produced for the building and construction industry to meet fire safety standards.
The substance was added to the Stockholm Convention in 2014 which meant that all countries signed up to the treaty should aim to eliminate its use, manufacture and importation.
However, the US is not a signatory to the Convention and it has therefore been the adoption of regulations in North America and other countries that have prompted companies to phase it out. Several US states, including Massachusetts, California and Washington, have also taken steps to address and manage certain flame retardants, including HBCD.
According to a Dow press release, HBCD is no longer being used in its XPS or EPS polystyrene insulation. It replaced the substance in stages, starting with Japan in 2014, the EU in 2015, Canada in 2016 and the US last year.
Owens Corning also said that in 2017 it completed a transition to a "fire retardant that contains no HBCD for our XPS foam insulation in North America". Its motivation, it says, is to meet regulations in Canada and market demand. Owens Corning did not say what alternative it was using instead of HBCD.
And following a review of its products in 2014, Kingspan decided to stop using HBCD "given concerns about its use in several end markets". It has been using an alternative fire retardant since 2016, but did not say what this is.
In 2016, the US EPA announced HBCD will be one of the first ten existing chemicals subject to risk evaluation under the new TSCA.
Dow is the only company to reveal its alternative. It said its "polymeric flame retardant technology", known as PolyFR, is a "butadiene styrene brominated copolymer". Through a licensing agreement, Dow has made its PolyFR alterntive available to Israel's ICL Industrial Products (ICL-IP), Albermarle Corp and Chemtura.
Unlike HBCD, PolyFR is a polymer with a higher molecular weight, so it is no longer bioaccumulative, according to Mark Barger, a chemical engineer at Dow and a fellow of the Society of Plastics Engineers.
In 2016, the EPA's Design for the Environment (DfE) programme released an alternative assessment report on HBCD. This identified butadiene styrene brominated copolymer as a "safer alternative ... that is unlikely to be released from the polystyrene". However, the report added "this alternative is inherently persistent. Its long-term behaviour in the environment is not currently known."
According to the Green Science Policy Institute, the possible health and ecological impacts of PolyFR, and its potential impurities and environmental breakdown products, are not yet known.
It said an estimated 23,000 metric tons of the polymeric flame retardant is being produced annually, and global production is expected to increase.
"PolyFR may provide a textbook example of a 'regrettable substitution'," the NGO said.