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).
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).[3]
| BDE-153 | 2,2′,4,4′,5,5′-hexa- bromodiphenyl ether | 0.15–8.7% | ||
| BDE-154 | 2,2′,4,4′,5,6′-hexa- bromodiphenyl ether | 0.04–1.1% | ||
| BDE-171 | 2,2′,3,3′,4,4′,6-hepta- bromodiphenyl ether | 0.17–1.8% | ||
| BDE-180 | 2,2′,3,4,4′,5,5′-hepta- bromodiphenyl ether | n.d.–1.7% | ||
| BDE-183 | 2,2′,3,4,4′,5′,6-hepta- bromodiphenyl ether | 13–42% | ||
| BDE-196 | 2,2′,3,3′,4,4′,5,6′-octa- bromodiphenyl ether | 3.1–10.5% | ||
| BDE-197 | 2,2′,3,3′,4,4′,6,6′-octa- bromodiphenyl ether | 11–22% | ||
| BDE-203 | 2,2′,3,4,4′,5,5′,6-octa- bromodiphenyl ether | 4.4–8.1% | ||
| BDE-206 | 2,2′,3,3′,4,4′,5,5′,6-nona- bromodiphenyl ether | 1.4–7.7% | ||
| BDE-207 | 2,2′,3,3′,4,4′,5,6,6′-nona- bromodiphenyl ether | 11–12% | ||
| BDE-209 | Deca- bromodiphenyl ether | 1.3–50% |
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.[5] Typically 12–15% of the weight of the final product will consist of octaBDE.[5]
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.[6] 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]
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] [7] [8]
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]
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.[9]
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]
The European Union has carried out a comprehensive risk assessment under the Existing Substances Regulation 793/93/EEC.[5] As a consequence, the EU has banned the use of octaBDE since 2004.[10]
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."[11] As of mid-2007, a total of eleven states in the U.S. had banned octaBDE.[12]
In May 2009, commercial octaBDE was added to the Stockholm Convention as it meets the criteria for the so-called persistent organic pollutants of persistence, bioaccumulation and toxicity.
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."[13]