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Brominated Flame Retardants
Summary
The consumption of brominated flame retardants (BFRs) with end products in Denmark in 1997 is estimated at 320-660 tonnes. Tetrabromobisphenol A (TBBPA) and derivatives accounted for about half of the consumption, and the consumption of these flame retardants is increasing. The more controversial compounds, polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) accounted for approximately 1% and 9%, respectively, of the consumption with end products. A marked shift away from PBDEs has taken place in Danish production and for a part of the imported products. The knowledge on the emissions of the brominated flame retardants to the environment is still very limited. Model estimates indicate that the major source of brominated flame retardants lost to the environment is evaporation from products in use. No recycling activities are taking place for materials containing brominated flame retardants. Broadly all electronic equipment, as well as a major part of other electrical devices, contains brominated flame retardants. For two large application areas - TV sets and computer monitors - the trend of the recent years has been a shift away from the use of brominated flame retardants. This is partly due to the influence of ecolabels. Today, alternative flame retardants are available for applications that quantitatively account for the major part of the consumption of brominated flame retardants. The current knowledge of the environmental properties of the substitutes is limited, however. For a number of applications that account for a major part of the BFRs used for Danish production, substitutes are still at the developmental stage.
Background and Objectives
The term 'brominated flame retardants' cover a large number of different organic substances, all with bromine in their molecular structure. Bromine has an inhibitory effect on the formation of fire in organic materials. Flame retardants are added to plastics and textiles in order to comply with fire safety requirements.
The most widely used substances - among these TBBPA, PBDEs and PBBs - contain one or more carbon rings, making them very stable and efficient in a large number of plastics.
The chemical stability of the substances - particularly in the cases of PBBs and PBDEs - is also the reason why brominated flame retardants for years have been in focus in the international environmental debate. PBDEs and PBBs, which are the most stable of the described BFRs, are spread widely in the environment, are bioaccumulated and are accumulated in sediments, where they are only very slowly degraded.
With the aim of reducing the release of brominated flame retardants to the marine environment, Denmark has committed itself in the Esbjerg Declaration of 1993, to promote the substitution of brominated flame retardants with less problematic substances if such are available.
Recent research has revealed that some of the brominated flame retardants are emitted to the indoor environment from the products in use. Increasing concentrations of PBDEs have been observed in human breast milk.
Risk assessments on three PBDEs and HBCD have been carried out within the EU since the mid nineties. The results of the assessments of the PBDEs are expected to be presented in 1999.
No previous assessments of brominated flame retardants have been carried out in Denmark. It is the aim of this study to establish an overview of the use of these substances in products manufactured in, and imported to, Denmark. In addition the purpose of the project is to assess the possibilities of and limitation for substitution of brominated flame retardants.
Studies in other countries have shown that the use of flame retardants has an important role in saving lives. This issue and more broadly the social advantages of the use of flame retardants has not been covered by the present study.
The Study
This study has been carried out in accordance with the paradigm for substance flow analysis of the Danish Environmental Protection Agency. The knowledge presented is based on data from Statistics Denmark, the Danish Product Register, the literature, market analyses, public institutions as well as from private organisations and companies. In the analysis, all the information has been hold together to describe the total flow of brominated flame retardants through the Danish society.
Data on the import of brominated flame retardants with polymer raw materials for production in Denmark has been obtained through a questionnaire in co-operation with the Danish Plastic Federation.
An attempt has been made to collect information on the contents of brominated flame retardants in imported goods via trade companies and importers. This has proven difficult, as most vendors do not know, whether the products in question contain brominated flame retardants. As a consequence, the analysis for a number of product types has been based on data on the European market for flame retardants and flame retarded polymers. Based on such information, it has been possible to determine which flame retardants are likely to be used in the different types of end products.
No measurements of the concentrations of brominated flame retardants in Danish waste water and sewage sludge have been found. Similarly no measurements of emissions from production or products in use are available. No Danish studies have been made on the fate of brominated flame retardants in the waste treatment systems. Hence, it has been necessary to estimate the potential loss of brominated flame retardants to the environment considering the few available foreign analyses and model estimates. The presented estimates of losses to the environment are therefore to be considered as the author's best estimate based on the existing knowledge.
Information on alternative flame retardants, and products containing alternatives, has been obtained from suppliers of flame retardants and plastic raw materials, as well as searches on the Internet and direct contact to producers using alternatives. Brominated flame retardants account only for about 15% of the Western European market for flame retardants. For many purposes, for instance carpets and PVC, other types of flame retardants are generally used. For this reason, only the applications where brominated flame retardants are used today, have been included in the assessment of alternatives.
In order to give a first overview, potential risks related to alternative flame retardants were identified on the basis of existing reviews.
This study has been carried out in 1998/99, and the data represent the 1997-situation.
The main conclusions of the project are:
 | The Danish consumption of brominated flame retardants with end products in 1997 is
estimated at 320-660 metric tonnes. The consumption can be broken down to about 47% TBBPA
and its derivatives, 12% PBDEs, 1% PBBs, 11% HBCD and 29% other brominated flame
retardants. About 44% of the total was used as reactive constituents. |
| Imported goods accounted for about 90% of the consumption with end products. |
| Brominated flame retardants are used in almost all product types containing electronics,
as well as in a significant part of other types of electrical equipment. |
| Brominated flame retardants are not produced in Denmark. The total import of brominated
flame retardants with chemicals, polymer compounds and plastic semi-manufactures for
production in Denmark was 260-390 tonnes in 1997. Of this TBBPA accounted for about 54%,
while PBBs and PBDEs in total accounted for only about 2%. |
| For production of insulating materials in Denmark 83-130 tonnes HBCD and brominated
polyetherpolyol were used. |
| In Danish manufacturing of housing for electronics, the brominated flame retardants have
been substituted with halogen-free flame retardants. The substitution has been driven by
the purpose of avoiding antimony trioxide, which is often used in combination with the
brominated flame retardants. Antimony trioxide is listed on the Danish list of hazardous
substances. (brominated flame retardants are not). |
| There has been a marked shift from PBDEs to TBBPA (and derivatives) in thermoplastics
used in Danish production. This trend is also seen for housing of imported electronics,
although PBDEs are still present in many imported products. Assessments on the overall
European consumption do only indicate a decrease in the consumption of PBDEs in Northern
Europe. |
| Model estimates indicate that the emissions of brominated flame retardants to the
environment are predominantly caused by evaporation from end products in use, whereas
production processes may contribute with minor amounts. Little is known so far regarding
the evaporation from end products. The actual emission rates and the fate of the
evaporated substances are still uncertain. |
| It is important to distinguish between additive and reactive uses. Brominated flame
retardants used as additives are estimated to have a much larger tendency to evaporate to
the surroundings, than substances chemically bound in the polymer structure. Examples of
reactive use are the incorporation of bromine in epoxy based printed circuit boards and
rigid polyurethane foam. |
| Discharges to waste water from products and production processes are modest. A major
part is estimated to originate from flame retarded textiles. This contribution is,
however, rather small compared to other European countries, where the use of brominated
flame retardants in textiles is more common. |
| For a number of electronic products, no alternatives are currently available. This is
reflected in the fact that the present ecolabels only have requirements regarding flame
retardants for large plastic parts in the products. |
| Alternatives exist for the major applications, printed circuit boards and housing. |
| Most of the alternatives have been assessed only to a very limited extent. Several of the substances have been demonstrated to have undesirable environmental effects, and there is a need to establish a better overview of the environmental properties of the alternatives. |
The results
The present study consists of two parts: a substance flow analysis of brominated flame retardants and an assessment of alternatives to brominated flame retardants.
Extended summary of the results and discussion of the substance flow analysis can be found in chapter 4.
The aim of the assessment of alternatives is to identify possibilities of and limitation for substitution of brominated flame retardants. Extended summary for the assessment of alternatives can be found in chapter 9.
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