Brominated Flame Retardants

4. Summary and Discussion of the Substance Flow Analysis

4.1 Consumption in Denmark
4.2 Emission and Disposal to the Environment and Landfills
4.3 Substance Flow Balance for Brominated Flame Retardants

4.1 Consumption in Denmark

The total consumption of brominated flame retardants with end products in Denmark is summarised in table 4.1.

The total consumption is estimated at 320-660 tonnes.

The principal fields of application were:

The consumption with electric and electronic equipment can be broken down to about 29% of the total consumption with printed circuit board assemblies, 21% with housing, 7% with other parts of electric appliances and machines, 2% with lighting, and 11% with products for wiring and power distribution.

The use of brominated flame retardants is very widespread. Brominated flame retardants are present in almost all products containing electronic components i.e. virtually all electronic products and means of transport and a large part of the electric products. Additionally brominated flame retardants are used in a significant part of plastics in contact with live parts in electric equipment. Switches, plugs, and sockets for lighting are only a few examples.

Unintended uses as contaminant

Natural occurrence of BFRs has not been reported. The total turnover of PBDEs with food is estimated at 0.4-0.8 tonnes per year. Fish is estimated to account for approximately half of the intake with food. The available data indicate that the turnover of TBBPA with fish is considerably lower than the turnover with PBDEs, but data on other BFRs than PBDEs and PBBs are scarce.

Specific substances

The consumption of the different groups of flame retardants is estimated with high uncertainty, as specific information on the content of flame retardants in imported products has been difficult to obtain. For some applications the actual flame retardants present in the products are estimated from more general information on the consumption of flame retardants in Western Europe and other parts of the World.

TBBPA and derivatives are estimated to account for about 47% of the total consumption. TBBPA is mainly used reactively for printed circuit boards and additively for housing of electric and electronic appliances and engineering thermoplastics. TBBPA and derivatives are estimated to account for a larger part of the total consumption than they do at the global and W. European market cf. section 1.3. The reason is that TBBPA and derivatives are estimated to account for the major part of BFRs used for housing of electronics and this may be specific for Northern Europe.

Table 4.1
Consumption of brominated flame retardants with end products in Denmark 1997

PBDEs are estimated to account for approximately 12% of the total consumption. It should be noted that the uncertainty on this value is as high as ± 50%. Major application areas are housing and engineering thermoplastics of electric and electronic equipment and plastic parts of transportation.

PBBs account for approximately 1%. Areas where the use of PBBs has been identified are engineering thermoplastics and rubber cables.

HBCD accounts for approximately 11%. Major application areas are expanded polystyrene (EPS and XPS) and textiles for automotive interior.

Other brominated flame retardants accounted for approximately 29%. Specific information of other BFRs in imported products has been difficult to obtain. Major applications are polyurethane insulation (brominated polyetherpolyol), housing of electronics (e.g. tetrabromophtalimide), transportation (e.g. tetrabromophthalic anhydride). Other BFRs may, however, be used within all application areas.

Reactive vs. additive use

When the flame retardants are used reactively and built into the polymer structure, the chemical substance per se is only present in the plastic in trace amount. The product may rather be considered a brominated thermoset with properties that are significantly different from the properties of the flame retardant compound that is used as precursor.

TBBPA used reactively for printed circuit boards may accordingly in the end products be considered another substance than TBBPA used as additive flame retardant in housing. On a global scale additive use of TBBPA has traditionally only accounted for about 10% of the total consumption /8/. Because of the substitution of TBBPA (and derivatives) for PBDEs in housing and other applications, the additive use is estimated to account for a considerably higher part of the consumption of TBBPA with end products in Denmark.

Other main applications by which the brominated flame retardants are used reactively are polyurethanes for insulation and technical laminates based on unsaturated polyester or epoxy.

The consumption of BFRs used as reactive flame retardants can roughly be estimated at about 44% of the total consumption.

Consumer applications of chemicals

Brominated flame retardants are not marketed for non-professional use. Sprays with flame retardants for self treatment of for instance textiles in cars are available, but to the knowledge of the authors the sprays do generally contain other flame retardants.

Trends in consumption with end products

There is no previous substance flow analysis of brominated flame retardants in Denmark.

For some of the traditional major applications, TV-backplates and housing of electronics, the trend in the consumption is downward. For TV-backplates the downward trend is general to all Europe. For the housing of electronics the trend is general to at least Northern Europe.

For other applications in electric and electronic equipment - for instance printed circuit boards - the consumption pattern has been unchanged during the last years, and the total consumption of BFRs for these applications is increasing due to an increase in the consumption of the end products.

The trend in the attitude to brominated flame retardants is that many producers are looking for substitutes for brominated flame retardants, but until now substitution has only had a minor influence on the total consumption of these compounds with end products.

Consumption for production processes in Denmark

Brominated flame retardants are not produced in Denmark. For production processes they are mainly imported with plastic compounds and laminates for production of printed circuit boards.

The total import of brominated flame retardants as chemicals and with semi-manufactures for production in Denmark is shown in table 4.2.

Table 4.2
Import of brominated flame retardants as chemicals and with semi-manufactures for production in Denmark

Consumption of plastic raw materials

TBBPA for thermoplastic polyester (PBT/PET) and brominated polyetherpolyol account for the major part of the consumption of BFRs with plastic compounds in Denmark. The thermoplastic polyesters are flame retarded with TBBPA (derivatives) or PBB, and are used for production of plastic parts for electric and electronic equipment, for instance switches, relays, parts of pumps and electromotors.

Brominated polyetherpolyol is used reactively for production of rigid polyurethane foam for insulation. HBCD is used for production of expanded polystyrene for export.

A minor part of TBBPA is used for housing of electronic equipment. BFRs are only used for a small part of the flame retarded polyamide. Polyamides with non-halogen flame retardants are widely used.

Trends in consumption for production in Denmark

A few years ago PBDE in plastics for housing of electronic appliances represented a major part of the total consumption for production in Denmark, but non-halogen flame retardants have replaced BFRs for most applications.

The consumption of PBDEs as chemical has decreased from about 20 tonnes in 1995 to about 1 tonne in 1997.

Comparison with an W. European average

In section 1.3 it was estimated that the Danish consumption of brominated flame retardants in 1997 should be approximately 600-800 tonnes if the consumption equalled the average W. European consumption. The estimated total in table 4.1 indicates that the consumption in Denmark in total may be a little lower than the average European consumption. The assessments are, however, not totally independent, as the Danish consumption within some application areas has been estimated with a sidelong glance to the W. European consumption figures.

This is in particular true with respect to the distribution of the single groups of flame retardants. A recent market analysis shows PBDEs to a large extent has been replaced by other brominated flame retardants; especially in The Netherlands, Germany and the Nordic countries. PBDEs are hardly used in Danish production and not used by large German suppliers of plastic raw materials. TBBPA and other BFRs have substituted for PBDEs in housing of electronic products on the N. European market and dominant producers of electronic products has a policy of avoiding PBDEs. Market analyses of the European flame retardant market did not show any significant decrease in the use of PBDEs from 1992 to 1996 and PBDEs accounted in 1996 for about 26% of the W. European BFR market (based on information covering 76% of the market). A recent market analysis estimates that the PBDEs only accounted for 11% of the W. European market for brominated flame retardants in 1998.

The is a very significant difference between the consumption of BFRs in Danish production of plastics parts and the distribution of BFRs on the W. European market. PBDEs in Danish production only accounted for about 2% of the total BFR consumption in 1997 in comparison to approximately 26% and 11% of the W. European market in 1996 and 1998, respectively.

4.2 Emission and Disposal to the Environment and Landfills

Based on model considerations, the total emissions from Danish sources in 1997 have been estimated as follows:

The estimated emissions to the environment and disposal to landfills are shown in table 4.3.

Table 4.3
Estimated emission of brominated flame retardants to the environments and disposal to landfills in Denmark 1997

Emission to the air

There are no Danish measurements of emission of brominated flame retardants. Hence, all estimates have been based on models and measurements from other countries.

The significance of the emission of brominated flame retardants from products in use has been demonstrated by chamber experiments and measurements in the indoor environment, but the actual rates are very uncertain. Similarly emissions from production processes have been demonstrated by environmental samples from the vicinity of production sites.

Based on model considerations evaporation from products in use and during production is estimated to be the major sources of emission of the flame retardants to the air. The emission of flame retardants used reactively is estimated to be insignificant, and PBDEs and other additively used flame retardants account for the major part of the emission.

When emitted the flame retardants will tend to adsorb to solid surfaces and particles in the air. The dust particles may be released to the environment by airing, end up in vacuum cleaning bags or attach to the interior of appliances. Dust attached to the interior of appliances may be released by dismantling of the appliances.

Discharge to waste water Although the use of brominated flame retardants with protective clothing in Denmark compared to other countries is very limited, laundry of clothing with BFRs is estimated to be one of the major sources of brominated flame retardants to waste water.

Roofing foils and particles containing brominated flame retardants - initially evaporated to the air from production processes and products in use - are estimated to be other major sources of brominated flame retardants to waste water.

Discharge to the aquatic environment

Brominated flame retardants in waste water will tend to follow the sludge. The total discharge to the aquatic environment with waste water effluents is estimated to be <0,068 tonne. As is the case with other organic compounds following the solid phase, the occasional discharges by heavy rainfall bypassing the treatment plants may account for a significant part of the total discharge to the aquatic environment.

Compared to the potential deposition of BFRs from the air, the discharge with waste water is presumably small. The potential deposition of emitted substances will be dependent on the atmospheric stability of the substances. PBDEs seem to be much more stable in the atmosphere than TBBPA and PBDEs emitted to the atmosphere may be spread over long distances.

Emission to soil

The only identified source of release of brominated flame retardants to soil is spreading of municipal sludge on agricultural soil. The flame retardants may to some extent be degraded during the digestion of the sludge, but data are not available for a quantification of the degradation.

Solid waste incineration In total 170-360 tonnes brominated flame retardants were disposed of to solid waste incineration. During the incineration the flame retardants will be destructed. Analyses of the fate of other organic compounds during incineration show that trace amounts of the compounds will pass the combustion chamber and end up in residuals from the incineration. For phthalates for instance up to 0.1% passes through the combustion chamber.

Flame retardants passing the combustion chamber may act as precursor for formation of brominated and mixed halogen dioxins and furans.

Landfilling

In total 90-200 tonnes brominated flame retardants were disposed of to landfills. Flame retardants in products disposed of to landfills may in the long term be released to the air or landfill leachate. Measurements of brominated flame retardants in landfill leachate have not been identified. It is not known to what extent the flame retardants will be degraded within the products or in the soil in the immediate vicinity of the products from where they are released.

4.3 Substance Flow Balance for Brominated Flame Retardants

A schematic representation of the estimated flow of brominated flame retardants through the Danish society is shown in figure 4.1.

Import/export

Approximately 90% of the electronic products produced in Denmark are exported. Building materials is the only major application area of brominated flame retardants where domestic production accounts for a significant share of the consumption; and still the domestic production account for less than half of consumption. It is roughly estimated that imported products account for approximately 90% of the consumption of brominated flame retardants with end products.

Figure 4.1
The estimated flow of brominated flame retardants through the Danish society in 1997

Recycling and deposition

There is at present no recycling of brominated flame retardants with plastics from discarded products. Production scrap is recycled for the same applications as the primary materials.

There are no Danish measurements of atmospheric deposition of brominated flame retardants. Data on atmospheric deposition have neither been identified in the literature.