Biphenyls polyhalogenated

In 1979, it was stated that poiybrominated aromatic ethers have received little attention (ref. 1). That statement is still applicable. Analyses to characterize this class of commercial flame retardants have been performed using UV (refs. 1-2), GC (refs. 1-6), and GC-MS (refs. 1-4). The bromine content of observed peaks was measured by GC-MS, but no identification could be made. The composition of poiybrominated (PB) diphenyl ether (DPE) was predicted from the expected relationship with polyhalogenated biphenyl, a class which has received extensive attention. NMR (refs. 3-6) was successfully used to identify relatively pure material which had six, or fewer, bromine atoms per molecule. A high performance liquid chromatography (HPLC) method described (ref. 1) was not as successful as GC. A reversed phase (RP) HPLC method was mentioned, but no further work was published. 

Anaerobic dehalogenation has also been observed in aromatic ethers including polychlorinated dibenzo[l,4]dioxins (Fennell et al. 2004 Yoshida et al. 2005). The anaerobic debromination of decabromodiphenyl ether is considered here since it is analogous to the dehalogenation of polyhalogenated biphenyls. 

Hepatic Effects. Hepatic changes were observed in one chronic human exposure to mirex, as well as in a number of workers exposed to chlordecone for intermediate or chronic durations. In the mirex study, human subjects (sex and number not specified) from a chronically exposed cohort from southeast Ohio (route of exposure not specified, assumed to be oral) were assessed for cytochrome P- 4501A2 induction using a breath test that measures caffeine metabolism. The subjects exposed to mirex had elevated caffeine metabolism as compared to negative control individuals (subjects with no known exposure to polyhalogenated biphenyls or other related chemicals) in which the metabolism did not increase (Lambert et al. 1992). In the chlordecone study, liver function and structure in 32 men exposed to high levels of chlordecone while employed for 1-22 months (5.6... 

Lainbert GH, Hsu CC, Humphrey H, et al. 1992. Cytochrome P4SOIA2 in vivo induction a potential biomarker of polyhalogenated biphenyls and their related chemical s effects on the human. Chemosphere 25(1 -2) 197-200. 

Ethylmorphine and benzphetamine are N-demethylated specifically by rodent cytochrome(s) P-450 (as opposed to cytochrome(s) P] -450) in the rat phenobarbital and the polyhalogenated biphenyls induce these demethylation reactions. However, it is clear that no such stimulation occurred in the rainbow trout (Table II). 

On the other hand, the metabolism of benzo[a]pyrene, ethoxy-coumarin and ethoxyresorufin, which are preferentially oxidized by rodent cytochrome P -450, was greatly induced by the polyhalogenated biphenyls and 3-naphthoflavone. Despite large changes in... 

The data so far presented indicates that monooxygenation may be induced in the rainbow trout by polyhalogenated biphenyls and polycyclic aromatic hydrocarbons, but not by phendbarbital-type inducing agents. 

Halvorson MR, Phillips TD, Safe SH, et al. 1985. Metabolism of aflatoxin BI by rat hepatic microsomes induced by polyhalogenated biphenyl congeners. Appl Environ Microbiol 49(4) 882-886. 

Haung Q, Rusling JF. 1995. Formula reduction potentials and redox chemistry of polyhalogenated biphenyls in a bicontinuous microemulsion. Environ Sci Technol 29(l) 98-103. 

Ruzo LO, Zabik MJ. 1975. Polyhalogenated biphenyls Photolysis of hexabromo and... 

Sepkovic DW, Byme JJ. 1984. Kinetic parameters of L-[ 125I]triiodothyronine degradation in rats pretreated with polyhalogenated biphenyls. Food Chem Toxicol 22(9) 743-747. 

Shepard EC, Phillips TD, Irvin TR. 1984. Aflatoxin BI metabolism in the rat Polyhalogenated biphenyl enhanced conversion to aflatoxin Ml. Xenobiotica 14(9) 741-750. 

Silberhom EM, Glauert HP, Robertson LW. 1990. Carcinogenicity of polyhalogenated biphenyls PCBs and PBBs. Crit Rev Toxicol 20(6) 439-496. 

Electron transfer properties of polyhalogenated biphenyls were investigated by cyclic voltammetry. The primary reduction peak of 4,4 -dichlorobiphenyl, involving replacement of halide with hydrogen in an irreversible ECE- type reaction, are under kinetic control of the initial ET step. Electrochemical transfer coefficients, standard potentials and standard heterogeneous rate constants were also estimated from the voltammetric data230. 

Khadikar PV, Singh S, Mandloi D, Joshi S, Bajaj AV. QSAR study on bioconcentration factor (BCF) of polyhalogenated biphenyls using the PI index. Bioorg Med Chem 2003 11 5045-50. 

James, M.O. and P.J. Fittle. Polyhalogenated biphenyls and phenobarbital evaluation as inducers of drug metabolizing enzymes in the sheepshead, Archosargus probatocephalus. Chem.-Biol. Interact. 36 229-248, 1981. 

Although the last two options are very Important when they occur, as exemplified by the unfortunate cases of thalidomide (1 ) and the polyhalogenated biphenyls (.2) respectively, the great majority of xenoblotlcs undergo enzymic metabolism and/or are eliminated unchanged. In animals. In most cases, metabolism favours the elimination of the compound by enhancing Its polarity... 

Borlakoglu JT, Wilkins JPG. 1993a. Correlations between the molecular structures of polyhalogenated biphenyls and their metabolism by hepatic microsomal monooxygenases. Comp Biochem Physiol 105C(1) 113-117. 

Smith AG, Francis JE, Green JA, et al. 1990b. Sex-linked hepatic uroporphyria and the induction of cytochromes P450IA in rats caused by hexacMorobenzene and polyhalogenated biphenyls. Biochem Pharmacol 40(9) 2059-2068. 

Barbiturates and similar compounds Drugs, some polyhalogenated biphenyls, DDT Diphenylhydantoin 2C, 3A4... 

Rusling, J. F. and C. L. Miaw. 1989. Kinetic estimation of standard reduction potentials of polyhalogenated biphenyls. Environ. Sci. Technol., 23 476-479. 

P.c.b.s PCBs PCB s Polychlorinated biphenyls, 9 Polychlorinated biphenyls, liquid, 9 Polychlorinated biphenyls, solid, 9 Polyhalogenated biphenyls, liquid, 9 Polyhalogenated biphenyls, solid, 9 Polyhalogenated terphenyls, liquid, 9 Polyhalogenated terphenyls, solid, 9... 

While any halogen may halogenate a polyphenyl, chlorine and bromine are by far the more usual. They result in a large number of possible polychlorinated biphenyls syn. p.c.b.s, PCBs, PCB s), polyhalogenated biphenyls, and polyhalogenated terphenyls. No longer produced commercially, halogenated polyphenyls were widely used for their exceptional qualities as heat-transfer fluids, solvents, lubricants, dust suppressants, and fire retardants (some equipment that relies on these chemicals, like electrical transformers and capacitors, remains in use). 

Polychlorinated Biphenyls PCB s Polyhalogenated Biphenyls, Liquid or Polyhalogenated Terphenyls, Liquid Polyhalogenated Biphenyls, Solid or Polyhalogenated Terphenyls, Solid This entry also covers appliances such as transformers and condensers containing polyhalo-... 

Chlorinated paraffins are claimed to be one of the lowest cost FRs besides the hydrated metal oxides. They can be used with antimony oxide as FRs in unsaturated polyester resin systems. Special grades have been developed by Dover Chemical in its Hordaresin and Chlorez ranges for flame retarding high-impact polystyrene, offering an absence of polyhalogenated biphenyls or dioxins, low cost, improved melt flow, and better UV stability than aromatic brominated FRs. They are also used in rubber compounds, where they can also improve tensile and tear properties of neoprene, SBR, and nitrile, and in EPDM rubber for electrical or roofing products. 

A recent study on the risk reduction of halogenated flame retardants (polyhalogenated biphenyls, precursors of dioxins and furans), commissioned by the Organization for Economic Cooperation and Development (OECD), has led to a voluntary industry commitment from the brominated flame retardant manufactures [153]. The key points of this commitment are as follows ... 

Poisonous Liquids, oxidizing, n.o.s. (Inhalation Hazard Zone A) 3122 44 Polyhalogenaled Biphenyls, solid 3152 31... 

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