Brominated flame retardants
Flame retardants are used to make it more difficult for a material to ignite or to reduce the spread of fire, but they do not make the material non-flammable.
Flame retardants may be either reactive, i.e. combine chemically with the material that is to be flame-retarded, or additive, i.e. be mixed with the material without being chemically combined. Additive substances are more loosely bound to the material and therefore leak out more readily in use of the material or when it becomes waste.
Brominated flame retardants are often regarded as being the most effective flame retardant. Relatively small amounts are needed to obtain high flame protection. When materials that have been protected with a brominated flame retardant burn, a chemical process starts which entails the fire being stopped in the initial stage so that the spread of fire can be prevented.
Around 41 tonnes of brominated flame retardants were imported into Sweden as raw material for industry in 2010 (link to brief statistics on flame retardants). Brominated flame retardants were also imported as contained in finished articles.
There are around 80 different types of brominated flame retardants, which have widely varying chemical properties. Knowledge of them varies. There are five brominated flame retardants that, historically, are the most widely used and about which there is considerable knowledge. These are pentabromodiphenyl ether, octabromodiphenyl ether, decabromodiphenyl ether, tetrabromobisphenol A and hexabromocyclododecane.
Penta-, octa- and decabromodiphenyl ether belong to the same chemical group of substances, polybrominated diphenyl ethers, abbreviated as PBDE. These have differing numbers of bromine atoms in their structure, pentaBDE having five, octa- having eight and deca- having ten bromine atoms. All three are persistent substances that are difficult to break down, while their bioaccumulation and toxicity differ.
PentaBDE is classified as environmentally hazardous and harmful to health. There is a risk of serious harm to health in exposure through skin contact and ingestion and harm may be caused to children during infancy. PentaBDE has been found to be present in breastmilk. In addition, pentaBDE is classified is very toxic to aquatic organisms and may cause long-term adverse effects in the environment. Here you can search in the Classification List. PentaBDE is also accepted as a POP subject to the LRTAP-convention and the Stockholm Convention.
Penta- and octaBDE above a particular concentration are prohibited in some articles and products within the EU. Polybrominated biphenols (PBB) and polybrominated diphenyl ethers (PBDE) including dekaBDE are banned to use in electrical and electronic products by the so called ROHS directive (directive 2002/95/EC). DecaBDE was earlier exempted from the ROHS-directive but the exemption will be repealed 1 June 2008. Here you can search in the Restricted Substances Database.
Hexabromocyclododecane (HBCDD) has a different chemical structure, a ring consisting of twelve carbon atoms and six bromine atoms bound to the ring. Sweden was rapporteur for the risk assessment of HBCDD within the EU’s Existing Substances Programme. The conclusions are that HBCDD is persistent, bioaccumulative and very toxic to aquatic organisms and can cause long-term adverse effects in the aquatic environment. In animal studies it have been shown that HBCDD can cause effects on the liver, probably by an increase of enzyme production, and that HBCDD can accumulate in the body. The risk assessment of HBCDD within the EU’s Existing Substances Programme is finalised.
HBCDD is identified as a Substance of Very High Concern, SVHC, and included on the candidate list (Reach). HBCDD is also included on the authorisation list, Annex XIV of Reach. Within the work of the Stockholm Convention on Persistent Organic Pollutants (POPs) HBCDD has been assessed as a POP and global ban, with some exceptions, will enter into force from 2014.
Tetrabromobisphenol A (TBBP A) has also been risk assessed under the EU’s Existing Substances programme. There are proposals for the substance to be classified as very toxic to aquatic organisms as it can cause long-term adverse effects in the aquatic environment. TBBP A is regarded as persistent and bioaccumulative.
For other brominated flame retardants, there is also still a lack of knowledge of effects on humans and the environment. The substances differ from the chemical point of view, although they all contain bromine. To obtain an acceptable assessment, each individual substance must be assessed separately. Of other brominated flame retardants, only vinyl bromide has been classified as carcinogenic to date. Here you can search in the Classification List.
DecaBDE– Report of a government commission. Report 1/09. Swedish Chemicals Agency 2009. (In Swedish with an English summary).
Hexabromocyclododecane (HBCDD) and tetrabromobisphenol-A (TBBPA), Government Commission Report report 3/06, Swedish Chemicals Agency, 2006. (In Swedish with an English summary).
Decabromodiphenylether - Prospects of a national ban. Report 5/04, Swedish Chemicals Inspectorate 2004. (In Swedish with an English summary).
Brominated flame retardants – Prospects of a national ban. Report 4/03, Swedish Chemicals Inspectorate 2003.
Flamskyddsprojektet (The flame retardants project). Report 16/95, Swedish Chemicals Inspectorate 1995.