Polychlorinated hexachlorobiphenyl

Interaction effects of PCDDs with other polychlorinated compounds or mixtures are not extensively documented. For example, certain polychlorinated hexachlorobiphenyls (PCBs) have a low toxic potency to induce cleft palate deformities in mice (Bimbaum et al. 1985). However, mixtures of 2,3,7,8-TCDD and 2,3,4,5,3, 4 -hexachlorobiphenyl resulted in a tenfold increase in incidence of cleft palate in mice. Thus, the toxicity of compounds such as 2,3,7,8-TCDD may be enhanced by compounds of relatively low acute toxicity, such as selected PCBs. Bimbaum etal. (1985) concluded that the widespread environmental occurrence of such combinations suggests a need for further evaluation of the mechanism of this interaction. 

Marks, T.A., G.L. Kimmel, and R.E. Staples. 1981. Influence of symmetrical polychlorinated biphenyl isomers on embryo and fetal development in mice. I. Teratogenicity of 3,3, 4,4, 5,5 -hexachlorobiphenyl. Toxicol. Appl. Pharmacol. 61 269-276. 

Solbakken, J.E., K. Ingebrigtsen, and K.H. Palmork. 1984. Comparative study on the fate of the polychlorinated biphenyl 2,4,5,2,4,5,-hexachlorobiphenyl and the polycyclic aromatic hydrocarbon phenanthrene in flounder (Platichthys flesus), determined by liquid scintillation counting and autoradiography. Mar. Biol. 83 239-246. 

Eriksson P (1996) Developmental neurotoxicology in the neonate-effects of pesticides and polychlorinated organic substances. Arch Toxicol Suppl 18 81-88 Eriksson P, Viberg H, Fischer C, Wallin M, Frediiksson A (2002) A comparison of developmental neurotoxic effects of hexabromo cyclododecane, 2,2, 4,4, 5,5 -hexabromodiphenylether (PBDE 153) and 2,2, 4,4, 5,5 -hexachlorobiphenyl (PCB 153). Organohalogen Comp 57 389-392... 

S. Safe and O. Hutzinger, Polychlorinated Biphenyls Photolysis of 2,4,6,2, 6 Hexachlorobiphenyl, Nature232 (1971) 641-42 O. Hutzinger et al., Polychlorinated Biphenyls Metabolic Behavior of Pure Isomers in Pigeons, Rats, and Brook Trout, Science 178 (1972) 512-14 O. Hutzinger et al., Identification of Metabolic Dechlorination of Highly Chlorinated Biphenyl in Rabbits, Nature 252 (1974) 698-99. 

Planar and nonplanar polychlorinated biphenyls (Fig. 5.2) differ in the type of induction they will cause. Thus, 3, 3, 4, 4, 5, 5 -hexachlorobiphenyl is a planar molecule, which is an inducer of the polycyclic hydrocarbon type. 2, 2, 4, 4, 6, 6 -Hexachlorobiphenyl is a nonplanar molecule due to the steric hindrance between the chlorine atoms in positions 2 and 6 and is a phenobarbital type of inducer. The variety and type of inducing agents are shown in Table 5.21. Some compounds may indeed be mixed types of inducers, and thus mixtures of planar and nonplanar polychlorinated biphenyls are found to act as inducers of both the polycyclic and phenobarbital type. 

CDDs = chlorinated dibenzo-p-dioxins CDFs = chlorinated dibenzofurons HpCDD = heptachlorodibenzo-p-dioxin HpCDF = heptachlorodibenzofuran HxCB = hexachlorobiphenyl HxCDD = hexachlorodibenzo-p-dioxin HxCDF = hexachlorodibenzofuran ND = not detected OCDD = octachlorodibenzo-p-dioxin OCDF = octachlorodibenzofuran PCB = polychlorinated biphenyl PeCDD = pentachlorodibenzo-p-dioxin PeCDF = pentachlorodibenzofuran TCB = tetrachlorobiphenyl TCDD = tetrachlorodibenzo-p-dioxin TCDF = tetrachlorodibenzofuran TEQ=Toxicity equivalency concentration. 

The photodechlorination of 2,2/,3,3/,6,6/-hexachlorobiphenyl and of three commercial mixtures of polychlorinated biphenyls solubilized in an aqueous solution of poly(sodium styrenesulphonate-co-2-vinylnaphthalene) was studied with the use of solar-simulated radiation426,427. The reaction was found to be photosensitized by the naphthalene antenna units present in the copolymer. Exciplex formation and generation of radical anions lead to dechlorination. 

Asmus and co workers81 studied the pulse radiolysis of polychlorinated biphenyls (PCB) in N2-saturated DCE solutions. The transient absorption spectrum at 5 /is after a 1 /is pulse showed either two distinct absorption maxima (as, e.g., for 3,3, 4,4 -tetrachloro-biphenyl) or a broad absorption band (in the case of 2,2, 4,4, 5,5 -hexachlorobiphenyl) or a broad maximum with an additional shallow shoulder (for 3,5-dichlorobiphenyl) in the range of 375 130 nm. It appears that the number and position of chlorine substituents determine the absorption category. Another absorption band was indicated in the near IR region, but could not be studied. The observed absorption in the 375-430 nm range is attributed to the radical cations from PCB, formed by charge transfer from the radical cation of the solvent ... 

Borlakoglu JT, Wilkins JPG. 1993b. Metabolism of di-, tri-, tetra-, penta- and hexachlorobiphenyls by hepatic microsomes isolated from control animals and animals treated with Aroclor 1254, a commercial mixture of polychlorinated biphenyls (PCBs). Comp Biochem Physiol 105C(1) 95-106. 

Rose N, Laib RJ, Brunn H, et al. 1985. Biotransformation and toxicity of polychlorinated biphenyls (PCB s) Investigation of initiating and promoting activities of 2,2, 4,5 -tetra- and 2,2, 4,4, 5,5 -hexachlorobiphenyl. Naunyn-Schmiedebergs Arch Pharmacol 330(Suppl) R21. 

Vos JG, Notenboom-Ram E. 1972. Comparative toxicity study of 2,4,5,2, 4, 5 -hexachlorobiphenyl and a polychlorinated biphenyl mixture in rabbits. Toxicol Appl Pharmacol 23 563-578. 

Chlorobenzene Dimer acid, hydrogenated Epoxy, bisphenol F N-(p-Ethoxycarbonylphenyl)-N -ethyl-N -phenylformamidine 2,2, 4,4, 5,5 -Hexachlorobiphenyl Polychlorinated biphenyls coatings, surface film Tetrahydrofuran coatings, surface lipophilic Octadecyltrichlorosilane coatings, surface PU paints Hexamethylene diisocyanate biuret Hexamethylene diisocyanate polymer coatings, surface PU varnishes Hexamethylene diisocyanate biuret Hexamethylene diisocyanate polymer coatings, surface textiles Tetrahydrofuran... 

Hexachlorobiphenyl Polychlorinated biphenyls transistor mountings Beryllium oxide transistors Lead sulfide transmission Tridecyl erucate transmitters, high capacity Diamond... 

McKinney, J.D. 1976. Toxicology of selected symmetrical hexachlorobiphenyl isomers correlating biological effects with chemical structure. Proceedings of the National Conference on Polychlorinated Biphenyl, November 19-21, 1975, Chicago, Illinois. U.S. Environmental Protection Agency Publication No. EPA-560/6-75-004, pp. 73-76. 

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