Hexachlorobenzene, polychlorinated

DDD Dichloro(chlorophenyl)-bis Ethane DDE Dichlorodiphenyldichloroethylene Dichlorobenzene, 1,2 Dichlorobenzene, 1,3 Dichlorobenzene, 1,4 Hexachlorobenzene Polychlorinated Benzenes Polychlorinated Biphenyls PCBs Aroclor Ring-Substituted Aromatics Tetrachlorobenzene Trichlorobenzene, 1,2,4 Saturated Alkyl Halides Bromodichloromethane Bromoform Tribromomethane Butyl Chloride Chlorobutane Carbon Tetrachloride Carbon Tetrafluoride Chloroform Trichloromethane Chloromethane Methyl Chloride Dibromochloromethane Dibromoethane, 1,2 Ethylene Dibromide Dibromomethane... 

Another major exposure route for humans is via contaminated food. For example, North America s Great Lakes, which are the largest body of freshwater in the world, are polluted with about 362 contaminants that were found in quantifiable amounts in the water, sediment, and biota (IJC 1983 USEPA 1994). The critical pollutants were identified as PCBs, DDT, dieldrin, toxaphene, mirex, methyl mercury, benzofa) pyrene, hexachlorobenzene, polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and alkylated lead. Some of these pollutants biomagnify in the aquatic food chain and can be detected in increased levels in cooked Great Lakes fish. Consequently, the blood serum levels of these chemicals are significantly increased in consumers of contaminated Great Lakes sport fish compared to people who do not eat such fish (Flumphrey 1983 Fiore et al. 1989 Sonzogni et al. 1991). 

Attention has been directed to the dechlorination of polychlorinated benzenes by strains that use them as an energy source by dehalorespiration. Investigations using Dahalococcoides sp. strain CBDBl have shown its ability to dechlorinate congeners with three or more chlorine substituents (Holscher et al. 2003). Although there are minor pathways, the major one for hexachlorobenzene was successive reductive dechlorination to pentachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,4-trichlorobenzene, and 1,4-dichlorobenzene (Jayachandran et al. 2003). The electron transport system has been examined by the use of specific inhibitors. lonophores had no effect on dechlorination, whereas the ATP-synthase inhibitor A,A -dicyclohexylcarbodiimide (DCCD) was strongly inhibitory (Jayachandran et al. 2004). 

Fig. 3 Scientific studies in water. Ph pharmaceuticals Ft phthalates Fu fungicides HA acidic herbicides HCB hexachlorobenzene PCBs polychlorinated biphenyls OCs organochlorine pesticides PPs polar pesticides...

Fig. 5 Scientific studies in biota. DDTs dichloro diphenyl trichloroethane HCB hexachlorobenzene HCHs hexachlorocyclohexanes OCs organochlorine pesticides OPs phosphorate pesticides PCBs polychlorinated biphenyls HBCD hexabromocyclododecane...

Ritter L, Solomon KR (1995) A review of the persistent organic pollutants DDT, aldrin, dieldrin, endrin, chlordane, heptachlor, hexachlorobenzene, mirex, toxaphene, polychlorinated biphenyls, dioxins and furans. In T.I.P.o.C.S. (IPCS) (ed) Geneve, Suisse... 

Knickmeyer, R. and H. Steinhart. 1989. On the distribution of polychlorinated biphenyl congeners and hexachlorobenzene in different tissues of dab (Limanda limanda) from the North Sea. Chemosphere 19 1309-1320. 

Terrence Collins is the Thomas Lord Professor of Chemistry at Carnegie Mellon University who contends that the dangers of chlorine chemistry are not adequately addressed by either academe or industry, and alternatives to chlorine and chlorine processors must be pursued. He notes, Many serious pollution episodes are attributable to chlorine products and processes. This information also belongs in chemistry courses to help avoid related mistakes. Examples include dioxin-contaminated 2,4,5-T, extensively used as a peacetime herbicide and as a component of the Vietnam War s agent orange chlorofluorocarbons (CFCs) polychlorinated biphenyls (PCBs the pesticides aldrin, chlordane, dieldrin, DDT, endrin, heptachlor, hexachlorobenzene, lindane, mirex, and toxaphene pentachlorophe-... 

Ritter, L., Solomon, K.R., Forget, J, 1995. An Assessment Report on DDT-Aldrin-Dieldrin-Endrin-Chlordan-Heptachlor-Hexachlorobenzene-Mirex-Toxaphene-Polychlorinated Biphenyls-Dioxins and Furans for the International Program on Chemical Safety. 

Hexachlorobenzene (HCB) was used as a pesticide to protect against fungus and in the manufacture of fireworks, ammunition, and synthetic rubber. This polychlorinated benzene now is foimd in coastal marine sediments. It also bioaccumulates in marine organisms. 

Source Hexachlorobenzene may enter the environment from incomplete combustion of chlorinated compounds including mirex, kepone, chlorobenzenes, pentachlorophenol, PVC, polychlorinated biphenyls, and chlorinated solvents (Ahling et al., 1978 Dellinger et al., 1991). In addition, hexachlorobenzene may enter the environment as a reaction by-product in the production of carbon tetrachloride, dichloroethylene, hexachlorobutadiene, trichloroethylene, tetrachloro-ethylene, pentachloronitrobenzene, and vinyl chloride monomer (quoted, Verschueren, 1983). 

G. Liljegren et al., Case-control Study on Breast Cancer and Adipose Tissue Concentrations of Congener Specific Polychlorinated Biphenyls, DDE and Hexachlorobenzene, Eur. J. Cancer Prev. 7 (1998) 155-40 R. J. Helzlsouer et al., Serum Concentrations of Organochlorine Compounds and the Subsequent Development of Breast Cancer, Cancer Epidemiol. Biomarkers. Prev. 8 (1999) 525-52 J. F. Dorgan, Serum Organochlorine Pesticides and PCBs and Breast Cancer Risk Results from a Prospective Analysis, Cancer Causes and Control 10 (1999) 1-11 G. A. S. Mendonca et al., Organochlorines and Breast Cancer a Case-control Study in Brazil, Int. 

Assaf-Anid, N.,Nies, L. Vogel, T. M. (1992). Reductive dechlorination cf a polychlorinated biphenyl congener and hexachlorobenzene by vitamin B12. Applied and Environmental Microbiology, 58, 1057-60. 

Halogenated semivolatile organic compounds (SVOCs) — Halogenated SVOCs may also contain molecules of chlorine, bromine, iodine, and/or fluorine. The degree of volatilization from halogenated SVOCs is much less than for HVOCs. The most common types of halogenated SVOCs include polychlorinated biphenyl (PCBs), pen-tachlorophenol (PCP), and hexachlorobenzene. 

The Stockholm Convention is a global treaty committing the international community to protecting human health and the environment from the potentially harmful effects of POPs (UNEP Chemicals, 2005). The United Nations Environment Programme (UNEP) has identified 12 most toxic POPs (the Dirty Dozen ) for control under the Convention, including 10 intentionally produced POPs pesticides/industrial chemicals (aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex, toxaphene and polychlorinated biphenyls (PCBs)) and two unintentionally produced POPs by-products (polychlorinated dibenzo-/ -dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)). In implementing the Convention, Parties to the Convention will take measures to restrict the trade, production and use of the intentional POPs and to reduce and, where possible, to ultimately eliminate the production and release of the unintentional POPs by-products. 

DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs) and hexachlorobenzene. Residues levels of industry-derived contaminants such as polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-/>-dioxins and dibenzofurans (PCDD/Fs) were also reviewed. Concentrations of these contaminants in different environmental compartments were expressed as unit equivalent to part-per-billion (ppb) level, unless otherwise specified. The cited values of concentrations from various literature sources were rounded to two significant digits for comparison. A number of factors can influence the concentrations in biological samples. Therefore, whenever possible, for biological samples the lipid normalized concentrations were cited for comparison. 

The sources of unintentionally produced POP chemicals, polychlorinated dibenzodioxins (PCDD), polychlorinated dibenzofurans (PCDF), and hexachlorobenzene (HCB), has been estimated through the National Implementation Plan (NIP) for Malaysia. However, an official report has not been made public. The draft final report on the assessment of unintentionally produced chemicals conducted by Universiti Sains Malaysia... 

Siyali, D.S., 1973. Polychlorinated biphenyls, hexachlorobenzene and other organochlorine pesticides in human milk. Med. J. Aust. 2, 815. 

Wagman, N., Strandberg, B., Tysklind, M. (2001) Dietary uptake and elimination of selected polychlorinated biphenyl congeners and hexachlorobenzene in earthworms. Environ. Toxicol. Chem. 20, 1778-1784. 

Hardell L. 1986. Some aspects of exposure to polychlorinated dibenzo-p-dioxins and dibenzofiirans in the ecological system. In Morris CR, Cabral JRP, eds. Hexachlorobenzene Proceedings of an International Symposium 77 243-247. 

Schecter A, Furst P, Kriiger C, et al. 1989d. Uevels of polychlorinated dibenzofurans, dibenzodioxins, PCBs, DDT, and DDE, hexachlorobenzene, dieldrin, hexachlorocyclohexanes, and oxychlordane in human breast milk from the United States, Thailand, Vietnam, and Germany. Chemosphere 18 445-454. 

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