Polychlorinated diphenyl ethers PCDEs

Fig. 7 Generic chemical structures of polyhalogenated compounds. X=C1, Br. (I) Polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs) (II) chlorophenols (CPs), bromophenols (BPs) (III) polychlorinated diphenyl ethers (PCDE), polybrominated diphenyl ethers (PBDE) (IV) polychlorinated dibenzo-p-dioxin (PCDD), polybrominated dibenzo-p-dioxin (PBDD) (V) polychlorinated dibenzofuran (PCDF), polybrominated dibenzofuran (PBDF) (VI) tetrabromobisphenol A (TBBPA)...

Handbook of Chemistry and Physics" (1983), 63. Edition, CRC Press, Boca Raton Kurz J, Ballschmiter K (1995), Fresenius J. Anal. Chem. 351 98-109. Isomer-specific determination of 79 polychlorinated diphenyl ethers (PCDE) in cod liver oils, chlorophenols and in a fly ash" Nestrick TJ, Lamparski LL, Crummett WB (1987), Chemosphere 16 777-790. Thermolytic surface reaction of benzene and iron(III) chloride to form chlorinated dibenzo-p-dioxins and dibenzofurans"... 

Table 16. Chemical name, chemical structure, molecular formula, molecular mass, water solubility (WS), n-octanol/water partition coefficient (log Kow)> and estimated or predicted bioconcentration factors on a wet weight basis (BCF ) and on a lipid basis (BCFl) of Polychlorinated Diphenyl Ethers (PCDEs) in fish and mussel... 

Polychlorinated diphenyl ethers (PCDE) are common impurities in chlorophenol formulations, which were earlier used as fungicides, slimicides, and as wood preservatives. PCDEs are structurally and by physical properties similar to polychlorinated biphenyls (PCB). They have low water solubility and are lipophilic. PCDEs are quite resistant to degradation and are persistent in the environment. In the aquatic environment, PCDEs bioaccumulate. These compounds are found in sediment, mussel, fish, bird, and seal. PCDEs show biomagnification potential, since levels of PCDEs increase in species at higher trophic levels. PCDEs are also detected in human tissue. Despite the persistence and bio accumulation, the significance of PCDEs as environmental contaminants is uncertain. The acute toxicity and Ah-receptor-me-diated (aryl hydrocarbon) activity of PCDEs is low compared to those of polychlorinated di-benzo-p-dioxins (PCDD) and dibenzofurans (PCDF). Due to structural similarity to thyroid hormone, PCDEs could bind to thyroid hormone receptor and alter thyroid function. Furthermore, PCDEs might be metabolized to toxic metabolites. In the environment, it is possible that photolysis converts PCDEs to toxic PCDDs and PCDFs. 

Polychlorinated diphenyl ethers (PCDE), also called bis(chlorophenyl) ethers and chlorodiphenyl oxides, are neutral aromatic compounds which resemble structurally polychlorinated biphenyls (PCB), except that one oxygen atom connects the phenyl rings. The empirical formula of the PCDEs is C12H10 nClnO, where n = 1-10. The structural formula of the PCDEs is given in Fig. 1. 

Polychlorinated diphenyl ethers (PCDEs) 10.1.4.1 2-Chlorodiphenyl ether (PCDE-1)... 

Kurz, J., Ballschmitter, K. (1999) Vapour pressures, aqueous solubilities, Henry s law constants, partition coefficients between gas/water (Kg ) -octanol/water (Kqw) and gas/octanol (Kg ) of 106 polychlorinated diphenyl ethers (PCDE). Chemosphere 38, 573-586. 

Polychlorinated diphenyl ethers (PCDE) were found in the ng/g range in cod liver oils [138]. The PCDE profiles were compared with those of PCDEs in chlorinated phenols, wood preserving formulations, and fly ash. The primary source of PCDEs are chlorophenols but sources other than those investigated appear to be involved as well. The majority of PCDEs found in cod liver oil are mono- or di-ortho- substituted and also have chlorines in the meta and para positions. 

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