Octabromodiphenyl ether

Octabromodiphenyl ether (octaBDE, octa-BDE, OBDE, octa, octabromodiphenyl oxide, OBDPO) is a brominated flame retardant which belongs to the group of polybrominated diphenyl ethers (PBDEs).

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Composition, uses, and production

Commercial octaBDE (also known as "Octabrom") is a technical mixture of different PBDE congeners having an average of 7.2 to 7.7 bromine atoms per molecule of diphenyl ether.^[1] The predominant congeners in commercial octaBDE are those of heptabromodiphenyl ether and octaBDE.^[1][2] The term octaBDE alone refers to isomers of octabromodiphenyl ether (PBDE congener numbers 194-205); the Infobox displays BDE-203 (2,2’,3,4,4’,5,5’,6-octabromodiphenyl ether).^[3]

OctaBDE is used in conjunction with antimony trioxide as a flame retardant in the housings of electrical and electronic equipment, mainly in the plastic acrylonitrile butadiene styrene, but also in high impact polystyrene, polybutylene terephthalate and polyamides.^[4] Typically 12–15% of the weight of the final product will consist of octaBDE.^[4]

The annual demand worldwide was estimated as 3,790 tonnes in 2001, of which Asia accounted for 1,500 tonnes, the Americas 1,500 tonnes, and Europe 610 tonnes.^[5] The United Nations Environment Programme reports "Since 2004, it [octaBDE] is no longer produced in the EU, USA and the Pacific Rim and there is no information that indicates it is being produced in developing countries."^[2]

Environmental chemistry

OctaBDE is released by different processes into the environment, such as emissions from the manufacture of octaBDE-containing products and from the products themselves.^[2] Elevated concentrations can be found in air, water, soil, food, sediment, sludge, and dust.^[2][6][7]

In the environment, "photolysis, anaerobic degradation and metabolism in biota" can cause debromination of octaBDE, which produces PBDEs with fewer bromine atoms "which may have higher toxicity and bioaccumulation potential."^[2]

Exposures and health effects

OctaBDE may enter the body by ingestion or inhalation.^[3] It is "stored mainly in body fat" and may stay in the body for years.^[3] In an investigation carried out by the WWF, "the brominated flame retardant chemical (PBDE 153), which is a component of the penta- and octa- brominated diphenyl ether flame retardant products" was found in all blood samples of 14 ministers of health and environment of 13 European Union countries.^[8]

The chemical has no proven health effects in humans; however, based on animal experiments, octaBDE may have effects on "the liver, thyroid, and neurobehavioral development."^[3]

Governmental actions

The European Union has carried out a comprehensive risk assessment under the Existing Substances Regulation 793/93/EEC.^[4] As a consequence, the EU has banned the use of octaBDE since 2004.^[9]

In the United States, as of 2005, "no new manufacture or import of" pentaBDE and octaBDE "can occur... without first being subject to EPA [i.e., United States Environmental Protection Agency ] evaluation."^[10] As of mid-2007, a total of eleven states in the U.S. had banned octaBDE.^[11]

It has been proposed that octaBDE be added to the Stockholm Convention as it meets the criteria for the so-called persistent organic pollutants of persistence, bioaccumulation and toxicity.^[2]

Alternatives

Alternatives to octaBDE include tetrabromobisphenol A, 1,2-bis (pentabromophenoxy) ethane, 1,2-bis(tribromophenoxy)ethane, triphenyl phosphate, resorcinol bis(diphenylphosphate), and brominated polystyrene; however, for each of these "the existing data on toxicological and ecotoxicological effects are fewer than for octabromodiphenyl ether."^[12]

References