Dibenzodioxins, polybrominated

H. Thoma, S. Rist, G. Hauschultz and 0. Hutzinger, "Polybrominated Dibenzodioxins and -Furans from the Pyrolysis of Some Flame Retardants," Chemosphere, 12L, 649 (1986). ... 

The dioxin toxic equivalency factor (TEF) approach is currently used worldwide for assessing and managing the risks posed by exposure to mixtures of certain dioxin-like compounds (DLCs). World Health Organization-TEF (WHO-TEE) values have been established for humans and mammals, birds, and (For new, refined values, see Ref. 12g.) It should be mentioned that 16 PCBs, the coplanar isomers with nonortho, monoortho, and diortho substitution by chlorine (overall, there are 209 isomers for this class of compounds) show dioxin-like toxic behavior. I-TE values are smaller, in the range of 0.0001-0.1. The most toxic isomers is 3,3, 4,4, 5-pentachlorodiphenyl with I-TE of 0.1. Polybrominated dibenzodioxins and furans with the 2,3,7,8 pattern also show dioxin-like toxicity, but their I-TE values are lower compared to PCDD/F. 

Dumler R, Thoma H, Lenoir D, et al. 1989b. Thennal formation of polybrominated dibenzodioxins (PBDD) and dibenzofurans (PBDF) from bromine containing flame retardants. Chemosphere 19(l-6) 305-308. 

MillT (1989), Environmental Fate of Polybrominated Dibenzodioxins and Dibenzofurans", US EPA, Office of Toxic Substances, Washington... 

UBA (Federal Environmental Agency)(1989) [Stat of facts. Polybrominated dibenzodioxins (PBDD) - Polybrominated dibenzofurans (PBDF). Second supplement Polybrominated biphenyls.] In Polybrominated dibenzodioxins and dibenzofurans (PBDD/ PBDF) from brominated flame retardants. Report of the working group on brominated flame retardants to the Environment Minister Conference. Bonn, Tederal Ministry for the Environment, Nature Conservation and Nuclear Safety, pp 95-97 (in German)... 

Figure 1. Schematic of reaction pathways to the production of polybrominated dibenzofurans and polybrominated dibenzodioxins from polybrominated diphenylethers (a common family of flame retardants for polymers). Note x+y can equal 5, 8, or 10 implying penta-, octa- or deca-substitu-tion.

As shown by several investigations [91], the bromine-rich polybromide phase by itself is hardly flammable and fireextinguishing properties have been reported occasionally. The formation of polybrominated dibenzo-dioxins (PBrDD) and furans (PBrDF) due to the plastic-containing housing of a zinc-flow battery cannot be totally neglected in the case of a fire, but their concentrations are far away from the tetrachloro dibenzodioxine (TCDD) toxic equivalents even in a worst-case scenario. 

H. Thoma, G. Hauschulz, E. Knorr and O. Hutzinger, "Polybrominated Dibenzofurans (PBDF) and Dibenzodioxins (PBDD) from the Pyrolysis of Neat Brominated Diphenylethers, Biphenyls and Plastic Mixtures of these Compounds,"Chemosphere, JJi, 277(1987). 

Dumler-Gradl R, Tartler D, Thoma H, et al. 1995. Detection of polybrominated diphenylethers (PBDE), dibenzofurans (PBDF) and dibenzodioxins (PBDD) in scrap of electronics and recycled products. Organohalogen Compounds 24 101-104. 

Incubation in soils showed that polybrominated biphenyls were resistant to degradation, but were apparently not taken up by plants or leached into groundwater [261]. Commercial formulations of brominated aromatic flame retardants had variable composition some contained highly brominated phenols, but no evidence of contamination with dibenzodioxins and dibenzofurans was found [198]. 

A majority of U.S. biomonitoring efforts measure such analytes as heavy metals, pesticides, cotinine, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins, phthalates, and volatile organic compounds (VOCs). Future population-based studies (such as NHANES) will include such chemicals as perfluorinated compounds, polybrominated diphenyl ethers (PBDEs), and perchlorate, on which little exposure information is available. 

Like other organohalogen compounds such as PCBs and DDT, PBBs and PBDEs are lipophilic, and persistent [2,3]. The high resistance towards acids, bases, heat, light, reduction and oxidation is disadvantageous when these compounds are discharged into the environment, where they persist for a long time. In addition, toxic compounds, polybrominated dibenzofurans (PBDFs) and dibenzodioxins (PBDDs), may be formed when these flame retardants are heated [5]. 

PAG PAH PBDE PCB PCDD/F PCR PM PM2.5 PNNL ppm ppt psi photoacid generator polycyclic aromatic hydrocarbon polybrominated diphenyl ether polychlorinated biphenyl polychlorinated dibenzodioxins and furans polymerase chain reaction particulate matter fine particulate matter (smaller than 2.5 microns in diameter) Pacific Northwest National Laboratory parts per million parts per trillion pounds per square inch... 

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