Potential measures for reduction of releases of heavy metals, POPs, HCFCs, BRFs and industrial greenhouse gases with particular reference to Russia, Ukraine and China

Potential measures for reduction of releases of heavy metals, POPs, HCFCs, BFRs and industrial greenhouse gases with particular reference to Russia, Ukraine and China

8 Brominated flame retardants

ABSTRACT
The term `Brominated Flame Retardants' (BFRs) covers a diverse group of or-ganic substances having in common that they contain bromine and act as flame retardants. Traditionally the most widely used substances among the brominated flame retardants have been TBBPA (tetrabromo bisphenol A), PBDEs (polybrominated diphenyl ethers), PBBs (polybrominated biphenyls) and HBCD (hexabromocyclododecane). Today PBBs are not produced in any country.

The environmental fate and effects of the BFRs vary considerably among the BFRs, even within the same substance group. In general congeners with lower bromine content are of more concern than congeners with higher bromine content. Two of the BFRs, hexabromobiphenyl (PBB with 6 bromine atoms) and pentabrominated diphenylether (PBDE with 5 bromine atoms) are considered for possible inclusion in the Stockholm Convention. The two substances are already or can easily be replaced by other flame retardants.

BFRs are mainly used in electric and electronic products, textiles and building materials. The electric and electronic products are traded on a global market, and the use of BFRs with finished products will probably be quite similar all over the world. The use of BFRs in building materials and textiles is more variable depending on local tradition and regulation.

The main measure for reduction of the releases of the BFRs is to reduce the use of the substances. The most problematic of the BFRs can easily be replaced by other BFRs, and many of the large companies in the electronics industry have phased out the use of PBDEs and PBBs as part of their corporate environmental strategy. For the major use areas non-halogenated alternatives are available, but for some minor areas no alternatives are available today.

The EU RoHS directive on the restriction of hazardous substances in electric and electronic products stipulates that these products shall not contain PBBs and PBDEs, but most probably the mostly used substance, deca-PBE will be exempted from the restriction, weakening the effect of the Directive as a driving force for the phaseout of the substances in the EU and other parts of the world.

It has not been possible to identify any surveys of BFR use or releases in Russia, Ukraine or China, and most probably they do not exist. An assessment of the uses of BFRs in the Arctic including Russia is included in a new ACAP project on BFRs. It is proposed to wait for the result of the survey, before new initiatives in Russia are launched.

It is deemed to premature to start initiatives in the other countries before some of the used BFRs are included in international agreements.

The term `Brominated Flame Retardants' (BFRs) covers a diverse group of organic substances having in common that they contain bromine and act as flame retardants. 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.

Because of the diversity of the group it is necessary to discuss the properties of the flame retardants in relation to specific sub-groups.

Traditionally the most widely used substances among the brominated flame retardants have been TBBPA (tetrabromo bisphenol A), PBDEs (polybrominated diphenyl ethers), PBBs (polybrominated biphenyls) and HBCD (hexabromocyclododecane). TBBPA, the PBDEs and the PBBs contain two chlorinated carbon rings, making them very stable and efficient in a large number of plastics. HCBD contains another type of cyclic structure making this substance stable.

The chemical stability of the substances is also one of the reasons why brominated flame retardants for years have been of environmental concern. PBDEs and PBBs, particularly the lower brominated congeners, are spread widely in the environment, are bioaccumulated and accumulated in sediments, where they are degraded only very slowly.

Some of the frequently used brominated flame retardants, TBBPA, HBCD and PBDEs, are present in sediment, mussels and fish. PBDEs have been found in whales and seals. Some of the PBBs and the PBDEs are highly hydrophobic and resistant to degradation processes. It is therefore possible that these chemicals may accumulate in aquatic sediments or bioconcentrate in living organisms. Signs of toxicity of individual PBB and PBDE to early life stages in rainbow trout were reported. The presence of some of the PBBs and PBDEs in mussels, fish, seals and dolphins as well as in sperm whales, which normally stay and feed in deep ocean water, combined with the ongoing industrial production of these compounds indicates that an environmental problem is rising (Simonsen et al. 2000).

In the Arctic, PBDEs have been detected in air and in biological samples from remote areas, although their levels are much lower than levels of some other POPs, such as PCBs (AMAP/ACAP 2003).

The toxicity varies considerably among the BFRs, even within the same subgroup. The effects of PBBs on laboratory animals include body weight loss, skin disorders, nervous system effects and injuries of livers, kidneys, thyroid glands, and immune systems (ATSDR 2004). In general little is known about the long-term effects of low level exposure (ATSDR 2004). The lower brominated congeners are of more concern that the higher brominated, e.g. penta-BDE (five bromine) and octa-BDE (eight bromine) are considered more problematic than deca-BDE (ten bromine).

Brominated flame retardants may further act as precursors or bromine donors for the formation of polybrominated dioxins and furans (PBDD/PBDFs) by incineration of the flame retarded materials. In particular the BFR with carbon ring structures, which may act as a precursor, is of concern.

8.1 Introduction to brominated flame retardants

The following is extracted from an assessment of BFRs and their alternatives published by the Danish EPA (Lassen et al. 1999) unless otherwise indicated.

Additive flame retardants are incorporated in the plastic either prior to, during, or, more frequently, following polymerisation. They are used especially in thermoplastics and thermoplastic polyesters. They act as plasticizers or fillers and are not built into the molecular structure of the plastics. They are sometimes volatile and can tend to bleed, so their flame retardancy may be gradually lost. High molecular weight products are developed to enable plastics to be made more permanently fire retardant by the additive method.

The most used additive brominated flame retardants are polybrominated diphenyl ethers (PBDEs), tetrabromobispehol A (also used as reactive BFR) and hexabromocyclododecane (HBCD), but a large number of different compounds are used addtively.

Reactive flame retardants are built chemically into the polymer molecule together with the other starting components. They are used mainly in thermosets, especially polyesters, epoxy resins and polyurethanes (PUR), in which they can be easily incorporated. The result is a brominated plastic with the original flame retardant present only at trace level as un-reacted constituent. The most used reactive brominated flame retardant is TBBPA, the main use of which is in printed circuit boards of electronic products.

The polybrominated diphenyl ethers (PBDEs) are a group of aromatic brominated compounds formed by substituting bromine for hydrogen in diphenyl oxide. The bromine content can vary between two and ten. Three different flame retardants are commercially available. They are referred to as penta-BDE, octa-BDE and deca-BDE, but each product is a mixture of different brominated diphenyl ethers. They are additive flame retardant, i.e. they are physically combined with the material being treated rather than chemically combined.

Penta-BDE is of most international concern, and the Parties to the Stockholm Convention have agreed that penta-BDE should be considered for possible in-clusion on the Convention's list of substances for elimination. Penta-BDE is nearly 100% used an additive flame retardant in flexible polyurethane foam used for mattresses, car seats and other products.

Polybrominated biphenyls (PBBs) are a group of halogenated hydrocarbons which are formed by substituting bromine for hydrogen in biphenyl. The bromine content can vary between two and ten.

Three different flame retardants have been commercially available. They are referred to as hexa-PBBs, octa/nona-PBBs and deca-PBBs, but each product is a mixture of different brominated diphenyl ethers (WHO 1994).

Hexa-PBBs were widely used in the USA in 1970s, but the use of all PBBs in the USA ceased in the late 1970s (WHO 1994).

Decabromobiphenyl (DeBB) was in 1998 the only brominated biphenyl in commercial use (Lassen et al. 1999). DeBB has traditionally been used as additive flame retardant for styrenic polymers and engineering plastics.

Of most international concern has been hexabromobiphenyl (the pure substance, which makes up the main part of the commercial hexa-PBBs), which is covered by the CLRTAP POPs protocol. No use of hexabromobiphenyl has been identified.

HBCD has traditionally been used as additive flame retardant for textiles coatings and production of flame retarded expanded polystyrene used for insulation in the building industry.

Tetrabromobisphenol A is mainly used as reactive flame retardant. In countries where the PBDEs have been phased out (e.g. Denmark) additively used TBBPA has to some extent been used as substitute for the PBDEs. Besides the Tetrabromobisphenol A, a number of derivates of the substance is used as flame retardants.

8.2 Sources and releases

The market volume of the major BFRs by region in 2001 is shown in table 8-1. The total demand for PBDEs was 67,000 tonnes, of which deca-BDE accounted for 56,000 tonnes. Asia represents the largest market, particularly for TBBPA, reflecting the significance of the production of electronic products in the Asian countries.

Table 8-1 Market volume of the major BFRs by region in 2001 in tonnes (BSEF 2005)

It has not been possible to identify any detailed survey of the global market for the remaining brominated flame retardants.

The total BFR market in Western Europe in 1998 is shown in table 8-2. The volumes of TBBPA, PBDEs and HBCD are at the same level as the 2001 volumes shown in table 8-1, but these BFRs represent only about 46% of the total volume, the remaining part taken up by a large number of other flame retardants. This may also be the fact for other parts of the world. The table clearly demonstrates the variety of substances used.

The PBBs (in the form of decabromobiphenyl) were in 1999 used in Western Europe in volumes of 600 t/years. The production of PBBs ceased in 2001, and PBBs are today according to BSEF (2005) not used in any part of the world.

Table 8-2 Western European market for brominated flame retardants, 1998 (IAL Consultants as quoted in Lassen et al. 1999)

*1 Some of these flame retardants may actually be used as additives. The TBBPA derivatives are cf. OECD 1994 used as additives (see table 3.1).

*2 Includes TBPA diester/ether diol and brominated polyetherpolyol in appendix 3.

*4 Include polydibromostyrene and brominated polystyrene in table 3.1 and appendix 3.

The main application areas of BFRs are electric and electronic products, building materials (insulation sheets) and textiles. The use of BFRs by end-use area in Denmark in 1997 is shown in table 8-3. The use of the substances in electric and electronic products most probably reflects the application pattern in most countries, as the electric and electronic products are traded on a global market. Contrary to this, the use of BFRs for building materials (expanded polystyrene) and textiles may vary considerably among countries dependent on tradition and national regulation. Imported products accounted for about 90% of the BFRs in products sold in Denmark reflecting the extensive import and export of BFR-containing products.

Table 8-3 Consumption of brominated flame retardants with end products in Denmark 1997(based on Lassen et al. 1999)

The sources of releases to the environment are dependent on the actual applications of each flame retardant. The total releases have until now only been estimated with high uncertainty, and no overview of the releases by substance is available from any country.

As an example of the releases of the PBDEs, the estimated worst-case releases to the environment and wastes of the EU Risk Assessment of deca-BDE are shown in table 8-5.

The main source of releases to air is releases from products in use, and the levels of the emission are of same size as the worst-case scenario used in the Danish substance flow analysis.

Textile washing is by far the main source of deca-BDE releases to wastewater. The releases will be highly dependent on whether the substance is used for textile application, and the releases by this pathway are estimated to be significantly lower in e.g. Denmark because BFRs are replaced by other flame retardants in most textiles used in Denmark (Lassen et al. 1999).

The main sources of releases to soil and surface water are flame retarded textiles and plastics remaining as waste in the environment. The releases by this pathway are in the Risk Assessment higher than the releases to air. These releases are highly dependent on the actual efficiency of the waste management systems and the public behaviour.

Table 8-4 Estimated worst-case releases of deca-BDE to waste and the environment (ECB 2002)

In a recent Japanese study the releases to the atmosphere from Japan are estimated by the use of the emission factors of i.a. the European Risk Assessment and the Danish substance flow analysis. The estimated emission is compared to emission estimated on the basis of actually observed air concentrations and a dissipation model. The authors conclude that the worst-case emission of the EU Risk Assessment is probably overestimated by a factor of 4 to 25 (Hirail and Sakail 2004).

It has not been possible to identify any information on the use and releases of BFRs in Russia. A survey of the use of BFRs in the Arctic countries including Russia has recently been approved by the Arctic Council. The ACAP project with Norway as the lead country will identify and develop safe waste-handling and recycling practices for BFR-containing products, identify alternative flame retardant chemicals and technologies and promote safe alternatives.

It has not been possible to identify any information on the use and releases of BFRs in China.

According to Bromine Science and Environment Forum (BSEF 2005) ICL Industrial Products (Dead Sea Bromine Group) has production of BFRs in China. A number of Chinese manufacturers advertise different BFRs on the Internet.

It has not been possible to identify any information on the use and releases of BFRs in Ukraine.

8.3 Main reduction measures

The main measure for reduction of the releases of BFRs is to reduce the use of the BFRs.

For specific BFRs of concern (e.g. PBBs or PBDEs) in practice the BFRs have often been replaced by other BFRs with less problematic environmental characteristics or with less described environmental characteristics. As an example PBDEs have for some purposes been replaced by additively used TBBPA. Many of the large companies in the electronics industry have phased out the use of PBDEs and PBBs as part of their corporate environmental strategy.

The PBBs and PBDEs can for all applications be replaced by other BFRs, but for some applications as indicated in table 8-5 alternatives to BFRs are not available. The information shown in table 8-5 is about 6 years old, but it is deemed that the information on alternatives still applies.

The availability of halogen-free flame retardants for the major application areas has been reviewed in Lassen et al. 1999 (table 8-5).

For several of the alternatives, however, only few data are available on the potential environmental and health effects, and some of the alternatives are themselves of environmental concern (Stuer-Lauridsen et al. 2000).

Table 8-5 Halogen-free flame retardants in commercial materials (Lassen et al. 1999)

*1 The list of halogen-free flame retardants is not complete, but indicates flame retardants in known commercial products cf. chapter 9. For some specific applications the flame retardants may not be immediately useful.

*2 Alternative materials are only mentioned where no flame retardants grades of the material are commercially available, or where alternative materials actually are chosen in order to substitute BFRs.

8.4 International regulation and agreements

Table 8-6 presents a summarised overview of the coverage in relevant agreements of the brominated flame retardants.

The CLRTAP - POPs protocol includes hexabromobiphenyl (one of the PBBs) for elimination. Hexabromobiphenyl is today most probably not produced in any country.

The Parties to the Stockholm Convention agreed at their meeting May 2005 that hexabromobiphenyl and penta-BDE should be considered for possible inclusion on the Convention's list of substances for elimination.

Penta-BDE is nearly 100% used as additive flame retardant in flexible polyurethane foam used for mattresses, car seats and other products. The penta-BDE was in 2001 primarily used in the Americas, whereas it was widely replaced by other flame retardants on the other markets (see table 8-1).

PBCDs, PBBs and HBCD are included in the OSPAR List of Chemicals for Priority Action, but release reduction of BFRs is not specifically addressed in the Convention text or any recommendation.

Hexabromobiphenyl is included in the HELCOM list of substances for immediate priority action, and substitution of BFRs in the leather industry is addressed by one recommendation.

It is beyond the present study to review EU instruments addressing the substances. However, the EU ROHS Directive may significantly influence the use of the PBDEs and PBBs also in other parts of the world.

The Directive stipulates that Member States shall ensure that electrical and electronic equipment put on the market after 1 July 2006 does not contain PBDEs and PBBs (among other substances). The Commission has in recent years evaluated whether deca-BDE should be exempted from the Directive. On a Commission-proposed vote on 19 April 2005, a majority of the EU Member States voted in favour of exempting Deca-BDE from the Directive. The required qualified majority of 72.3% for immediate adoption was however not reached, so the proposal has now been sent to the EU Council of Ministers. They have a maximum of three months to come up with a decision.

EU has adopted a general restriction on the marketing and use of penta-BDE and octa-BDE in all products from 15 August 2004.

Table 8-6 Summarised overview of the coverage of brominated flame retardants in relevant agreements

8.5 Overview of existing activities

Only one project specifically addressing the use and releases of brominated flame retardants has been identified (table 8-7).

Table 8-7 Identified initiatives in the Russian Federation, Ukraine and China addressing brominated flame retardants