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ARCHIVED - Environmental Screening Assessment Report on Polybrominated Diphenyl Ethers (PBDEs) - Draft for Public Comments
Identity, Uses and Sources of Release
PBDEs comprise a class of substances consisting of 209 possible congeners with 1–10 bromine atoms. The following seven PBDE homologues are on the Domestic Substances list (DSL) and were identified in the pilot project list of 123 substances and are considered in this assessment:
- tetrabromodiphenyl ether (benzene, 1,1'-oxybis-, tetrabromo derivative; tetraBDE) (CAS No. 40088-47-9);
- pentabromodiphenyl ether (benzene, 1,1'- oxybis-, pentabromo derivative; pentaBDE) (CAS No. 32534-81-9);
- hexabromodiphenyl ether (benzene, 1,1'-oxybis-, hexabromo derivative; hexaBDE) (CAS No. 36483-60-0);
- heptabromodiphenyl ether (benzene, 1,1'-oxybis-, heptabromo derivative; heptaBDE)(CAS No. 68928-80-3);
- octabromodiphenyl ether (benzene, 1,1'-oxybis-, octabromo derivative; octaBDE) (CAS No. 32536-52-0);
- nonabromodiphenyl ether (benzene, 1,1'-oxybis-, nonabromo derivative; nonaBDE) (CAS No. 63936-56-1); and
- decabromodiphenyl ether; bis(pentabromophenyl) ether (benzene, 1,1'-oxybis[2,3,4,5,6-pentabromo-; decaBDE) (CAS No. 1163-19-5).
These PBDEs are found in three commercial mixtures, typically referred to as Pentabromodiphenyl Ether (PeBDE), Octabromodiphenyl Ether (OBDE) and Decabromodiphenyl Ether (DBDE). PeBDE is predominantly a mixture of pentaBDE, tetraBDE and hexaBDE congeners, but may also contain trace levels of heptaBDE and tribromodiphenyl ether (triBDE) congeners. OBDE is a mixture composed mainly of heptaBDE, octaBDE and hexaBDE, but may also contain small amounts of nonaBDE and decaBDE. Current formulations of DBDE are almost completely composed of decaBDE and a very small amount of nonaBDE.
PBDEs are used mainly as additive flame retardants in polymer resins and plastics and, to a lesser extent, adhesives, sealants and coatings. Additive flame retardants are physically combined with the material being treated rather than chemically bonded as in reactive flame retardants; therefore, they are more susceptible, to a certain extent, to migration and loss from the polymer matrix. It has been estimated that approximately 90% or more of PeBDE produced globally is used in polyurethane foams in office and residential furniture, automotive upholstery, sound insulation and wood imitation products (WHO 1994; European Communities 2000; RPA Ltd. 2000). Most OBDE produced globally is added to polymers (mainly acrylonitrile butadiene styrene), which are then used to produce computers and business cabinets, pipes and fittings, automotive parts and appliances (WHO 1994; European Communities 2002b). DBDE is used as a flame retardant, to a large extent in high-impact polystyrene and other polymers, with broad use in computer and television cabinets and casings, general electrical/electronic components, cables and textile back coatings (OECD 1994; European Communities 2002a).
The total worldwide market demand for PBDEs was about 67 390 tonnes in 2001, including 56 100 tonnes of DBDE, 7500 tonnes of PeBDE and about 3790 tonnes of OBDE (BSEF 2003). There are significant differences in the usage of PBDEs by continent (see Table 1). The most apparent difference is that PeBDE is used almost exclusively in the Americas.
a All countries in North, South and Central America were included.
b All countries in Eastern and Western Europe were included.
c Australia, New Zealand and the Indian subcontinent were included.
Results from a Section 71 Notice with Respect to Certain Substances on the Domestic Substances List (DSL) conducted for the year 2000 indicated that no PBDEs were manufactured in Canada, although approximately 1300 tonnes of PBDE commercial products (for manufacturing into finished articles) were imported into the country (Environment Canada 2001). Based on quantities reported, PeBDE was imported in the greatest volume, followed by DBDE. A very small amount of OBDE was imported into Canada in 2000. The volumes reported do not include quantities imported in finished articles.
PBDEs may be released to the environment during manufacturing and polymer processing operations, throughout the service life of articles containing them and at the end of article service life during disposal operations.
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