Polybrominated diphenyl oxide

Hardy ML. 2000b. The toxicity of the commercial polybrominated diphenyl oxide flame retardants DBDPO, OBDPO, PeBDPO. Organohalogen Compounds 47 41-44. 

Hardy ML. 2002b. The toxicology of the three commercial polybrominated diphenyl oxide (ether) flame retardants. Chemosphere 46(5) 757-777. 

Polybrominated diphenyl oxide (PBIX)) llecabromodiphenyl Widely used in plastics such as ABS uncertain future because possible pollution during incineration. Especially useful in polyamides and PBTs polyesters good resistance to high processing temperatures and weathering, good colour stability used at low concentrations. 

Polybrominated diphenyl oxide (PBDO) compounds are suitable for most plastics, except PS foam. They have an uncertain future because of fears about possible air pollution during the incineration of plastics waste. 

The International Program for Chemical Safety (IPCS) of the World Health Organization has made several recormnendations. Polybrominated diphenyls production (France) and use should be limited because of the concern over high persistency, bioaccumulation and potential adverse effects at low levels. There is limited toxicity data on deca- and octabromodiphenyls. Commercial use should cease unless safety is demonstrated. For the polybrominated diphenyl oxides, a Task Group felt that polybrominated dibenzofurans, and to a lesser extent the dioxins, may be formed. For decabromodiphenyl oxide, appropriate industrial hygiene measures need to be taken and environmental exposure minimized by emission control. Controlled incineration procedures should be instituted. For octabromodiphenyl oxide, the hexa- and lower isomers should be minimized. There is considerable concern over persistence in the environment and the accumulation in organisms, especially, for pentabromodiphenyl oxide. 

Decabromodiphenyl ether (BDE-209) is a major industrial product from the polybrominated diphenyl ethers used as flame retardants derivatives of this product have been detected in the environment. After exposure to the land surface, these contaminants adsorb on soil materials and may reach the atmosphere as particulate matter these particulates are subsequently subject to photolytic reactions. In this context, Ahn et al. (2006) studied photolysis of BDE-209 adsorbed on clay minerals, metal oxides, and sediments, under sunhght and UV dark irradiation. Dark and light control treatments during UV and sunlight irradiation showed no disappearance of BDE-209 during the experiments. Data on half-lives and rate constants of BDE-209 adsorbed on subsurface minerals and sediments, as determined by Ahn et al. (2006) and extracted from the literature, are shown in Table 16.6. 

Fig. 16.19 GC-ECD chromatograms showing appearance of polybrominated diphenyl ether (PBDE) congeners, after sunlight irradiation of BDE-209 (retention time = 88.7 min) adsorbed on montmorillonite, at different times. Reprinted with permission from Ahn MY, Filley TR, Jafvert CT, Nies L, Hua I, Bezares-Cruz J (2006) Photodegradation of decabromodiphenyl ether adsorbed onto clay minerals, metal oxides, and sediment. Environ. Sci. Technol. 40 215-220. Copyright 2006. American Chemical Society...

Phosphoric Acid Phosphorus Photoallergens Photochemical Oxidants Phthalate Ester Plasticizers Physical Hazards Picloram Picric Acid Piperazine Piperonyl Butoxide "Plants, Poisonous" Platinum (Pt) Plutonium (Pu) Poinsettia Poisoning Emergencies in Humans Pokeweed Pollutant Release and Transfer Registries (PRTRs) Pollution Prevention Act "Pollution, Air" "Pollution, Air Indoor" "Pollution, Soil" "Pollution, Water" Polybrominated Biphenyls (PBBs) Polybrominated Diphenyl Ethers (PBDEs) Polychlorinated Biphenyls (PCBs)... 

Hamm, S., Strikkeling, M., Ranken, P. F., and Rothenbacher, K., Determination of polybrominated diphenyl ethers and PBDD/Fs during the recycling of high impact polystyrene containing decabromodiphenyl ether and antimony oxide, Chemosphere, 44, 1353-1360, 2001. 

ICP-OES, along with ICP-MS and X-ray fluorescence (XRE), is used for the analysis of the materials in electronic equipment. The EU has established directives on the disposal of waste electrical and electronic equipment (WEEE) and the restriction of the use of hazardous substances (RoHS) in electronic equipment sold in, into, and out of the EU. The maximum allowable quantities in electrical equipment of the following hazardous substances are 0.1% by weight for Pb, hexava-lent chromium (CrVI), mercury, and polybrominated biphenyl and polybrominated diphenyl ethers (PBDEs) and 0.01% by weight for Cd. Pb, Hg, Cd, and total Cr can be measured by ICP-OES, while the determination of hexavalent chromium requires a separation step in order to determine the oxidation state. This can be done using a hyphenated instrument, described in the following. Total bromine can also be measured by ICP-OES, but the determination of the PBDEs is generally done by GC-MS, described in Chapter 12. The WEEE/RoHS requirements have led many instrument manufacturers to have an installed method template for such analyses in their software. 

Legislative Issues. The European Union s RoHS and WEEE directives (the WEEE directive addresses waste electronic equipment and recycling requirements) affect not only the lead used in printed circuits, but the flame retardants used in the resin system as well.The RoHS directive restricts the use of specific types of brominated flame retardants. The restricted class of compounds consists of polybrominated biphenyls (PBBs) and polybromi-nated biphenyl oxides (PBBOs), also called polybrominated diphenyl ethers (PBDEs). The generic structure of these compounds is shown in Fig. 7.13. Specific compounds within these classes of flame retardants can vary in their toxicity, and given the dynamic nature of legislative initiatives, it is important to check the current status of these compounds when making decisions on what materials to use. 

The HO -initiated oxidation of 2,4,4 -tribromodiphenyl ether (BDE-28) in the atmosphere and in water solution has been studied and found to occur more readily in the former, especially at the less-brominated Ph ring. The hydrox-ylated dibrominated diphenyl ethers (HO -PBDEs, PBDE = polybrominated diphenyl ethers) are formed through direct bromine-substitution reactions or secondary reactions of HO adducts. Polybrominated dibenzo-p-dioxins resulting from o-HO -PBDEs are favoured products compared with polybrominated dibenzofurans generated by bromophenols and their radicals. The complete degradation of HO adducts in the presence of O2/NO, which generates unsaturated ketones and aldehydes, is less feasible compared with the H-abstraction pathways by 03." ... 

Since the technology is still developing, the industry has not yet focused its choice on one or two leading organo-bromine compounds. Rather, many manufacturers and many users of these flame retardants report serious interest in a wide variety of structures. Those most frequently mentioned in the technical literature, in approximate order of importance, are [2, 19, 21, 22, 25, 26], as follows decabromo diphenyl oxide, ethylene bis(tetrabromo phthalimide), tetradecabromo diphe-noxy benzene, ethylene bis(dibromo norbornane dicar-boximide), octabromo diphenyl oxide, hexabromo cyclo dodecane, tetrabromo dipentaerythiitol. In Europe, the organo-bromine compounds mentioned are quite different, mostly based on ethers of tetrabromo bisphenol A and while Europeans are more concerned about possible toxicity, paradoxically they are more likely to use polybrominated biphenyls, which would be taboo in the US [2, 28]. 

Polybrominated diphenyl ethers have a large number of congeners, depending on the number and position of the bromine atoms on the two phenyl rings. Commercial brominated diphenyl ethers are produced by the bromination of diphenyl oxide. Brominated diphenyl ethers are used as flame retardants. 

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