Polychlorinated dibenzo-furans

Dioxin and Furan Emissions. The emissions of polychlorinated dibenzo-/)-dioxins (PCDD) and polychlorinated dibenzo-furans (PCDF) from incinerators (4) are of interest to the pubHc, scientists, and engineers. The U.S. EPA classifies 2,3,7,8-tetrachlorodibenzo-/)-dioxin (2,3,7,8-TCDD) as the most potent carcinogenic compound it has evaluated. It is also Hsted as the agency s most potent reproductive toxin (4). 

PCBS (polychlorinated biphenyls) Toxic synthetic chemicals with excellent heat resistance and low electrical conductivity properties. Now little used but considerable quantities remain in old electrical equipment. Produces dioxins and polychlorinated dibenzo-furans when burned below 1200°C. PCBs are toxic and bio-accumulative. 

WHO has conducted three international studies of PCBs, polychlorinated dibenzodioxins, and polychlorinated dibenzo-furans in human milk during 1987-2003 (WHO 2000). The first two surveys were conducted in 1987-1988 and 1992-1993 in a number of European countries. The third, conducted in 2000-2003, included additional countries. A fourth survey has been developed with the intent to assess the persistent organic pollutants (POPs) found in human milk so that each country can better identify and set priorities among POPs for remedial action (WHO 2000). The sample population will include at least 50 mothers from each country who are planning to breastfeed (WHO 2005). Two sampling periods have been proposed, the first to obtain a baseline sample of POPs in representative... 

As noted earlier, polychlorinated dibenzo dioxins (PCDD) and polychlorinated dibenzo furans (PCDF) are two important classes of potentially toxic by-products that can form in trace levels (e.g., less than parts per... 

Buser, H. R., H. P. Bosshardt, and C. Rappe. 1978. Formation of polychlorinated dibenzo-furans from the pyrolysis of individual PCB isomers. Chemosphere 3 157-61. 

Lake, J.L., P.F. Rogerson, and C.B. Norwood. 1981. A polychlorinated dibenzo-furan and related compounds in an estuarine ecosystem. Environmental Science and Technology 5 549-553. 

Evers EHG, HJC Klamer, RWPM Laane, HAJ Covers (1993) Polychlorinated dibenzo- -dioxin and dibenzo-furan residues in estuarine and coastal North Sea sediments Sources and distribution. Environ Toxicol Chem 12 1583-1598. 

Leung AOW, Luksemburg WJ, Wong AS, Wong MH (2007) Spatial distribution of polybrominated diphenyl ethers and polychlorinated dibenzo-p-dioxins and dibenzo furans in soil and combusted residue at Guiyu, an electronic waste recycling site in southeast China. Environ Sci Technol 41 2730-2737... 

In addition, the concern about e-waste not only focuses on its vast quantity generated daily, but also more on the need to handle the toxic chemicals embedded in it. It is well known that e-waste contains lead, beryllium, mercury, cadmium (Cd), and brominated flame retardants (BFRs) among other chemical materials [3]. Furthermore, highly toxic chemicals such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated dibenzo-p-dioxins and dibenzo-furans (PBDD/Fs) can be formed during the recycling process [4]. 

Bignert, A., M. Olsson, P.A. Bergqvist, S. Bergek, C. Rappe, C. de Wit, and B. Jansson. 1989. Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzo-furans (PCDF) in seal blubber. Chemosphere 19 551-556. 

Incineration of domestic waste is also a contributor to environmental pollution. One more source of dioxins is pulp-and-paper industry. Comparatively new ways of forming polychlorinated dibenzo-p-dioxins and furans are high-temperature processes like copper melting in electric arc furnaces, and production of magnesium, nickel and, possibly, other metals of their chlorides. 

NP NPEC OC OP OPEC PCB PCDBT PCDD PCDF PCP PFB RA TCA TCDD TCF TCMTB TOC VSC VOC Nonylphenol Nonylphenol ethoxycarboxylate Organo chlorine Octylphenol Octylphenol ethoxycarboxylate Polychloroinated biphenyls Polychlorinated dibenzothiophene Polychlorin ated dib enzo-p - dioxins Polychlorinated dibenzo-p-furans Pentachlorophenol Pentafluorobenzyl Resin acids 2,4,6-Trichloroanisole Tetrachloro dibenzo dioxin Totally chlorine- free 2-(Thiocyanomethylthio)-benzothiazole Total organic carbon Volatile sulphur compounds Volatile organic compounds... 

Key words Polychlorinated dibenzo-p-dioxins (PCDDs) polychlorinated dibenzo-p-furans (PCDFs) sewage sludge household sewage and municipal wastewater treatment plant (MWTP)... 

Polychlorinated Dibenzo-(p)-Dioxins and Dibenzo-Furans. Another group of compounds that we need to specifically address are the polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzo-furans (PCDFs) (Fig. 2.15). The PCDDs and PCDFs are not intentionally produced but are released into the environment from various combustion processes and as a result of their occurrence as unwanted byproducts in various chlorinated chemical formulations (e.g., chlorinated phenols, chlorinated phenoxy herbicides see Alcock and Jones, 1996). Because some of the PCDD and PCDF congeners are very toxic (e.g., 2,3,7,8-tetrachloro dibenzo-p-dioxin, see margin), there have been and still are considerable efforts to assess their sources, distribution, and fate in the environment. Similarly to the PCBs or DDT (see above), the PCDDs and PCDFs are highly hydrophobic and very persistent in the environment. It is therefore not surprising that they have also been detected everywhere on earth (Brzuzy and Hites, 1996 Lohmann and Jones, 1998 Vallack et al., 1998). Finally, we should note that polybrominated diphenylethers (PBDEs, see margin) that, like the PBBs (see above), are used as flame retardants, are of increasing environmental concern (de Boer et al., 2000). 

Formation of polychlorinated dibenzo(p) dioxins and furans (PCDD/PCDF) in waste combustion has received considerable attention, because dioxins even in very small concentrations are believed to be harmful to humans. Sources of PCDD/PCDF include the waste itself, gas-phase and heterogeneous reactions within the combustion zone, and catalyzed reactions in the low-temperature region downstream [352],... 

A study of the soil of a Douglas fir forest in The Netherlands spiked with 37CI -chloride demonstrated that chlorinated phenols, dibenzo-p-dioxins, and dibenzo-furans are produced naturally in the humic soil layer probably via chloroperoxidase chemistry (Scheme 3.5) (1712). Twenty polychlorinated dioxins and furans were found to be produced naturally in this study, including the highly toxic 2,3,7,8-tetra- (2246), 1,2,3,7,8-penta- (2247), and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin (2248). The major congeners found are 4-chloro- (2249), 1,7-dichloro-... 

As discussed in the earlier survey (1), a biogenic source of polychlorinated dibenzo-p-dioxins and dibenzofurans is peroxidase-catalyzed transformation of chlorophenols as first reported by Oberg and Rappe (2041-2044). More recent studies confirm these observations (2045-2048). In addition to lactoperoxidase and horseradish peroxidase, human leukocyte myeloperoxidase catalyzes in vitro formation of dioxins and dibenzofurans from chlorophenols (2046, 2047). Formation rates are in the pmol/mol range (Scheme 3.6) demonstrating that a human biosynthesis of dioxins and furans is not only possible but also likely. These observations are reinforced by the reported in vivo (rats) conversion of the pre-dioxin nona-chloro-2-phenoxyphenol to octachlorodibenzo-p-dioxin (OCDD) (2049), and the production of hepta- and octachlorodibenzo-p-dioxin in the feces of cows fed pentachlorophenol-treated wood (Scheme 3.7) (2050, 2051). 

Wunderli S, Zennegg M, Dolezal IS, Gujer E, Moser U, Wolfensberger M, Hasler P, Noger D, Studer C, Karlaganis G (2000) Determination of Polychlorinated Dibenzo-p-dioxins and Dibenzo-furans in Solid Residues from Wood Combustion by HRGC/HRMS. Chemo-sphere 40 641... 

Ruokojarvi P, Ettala M, Rahkonen P, Tarhanen J, Ruuskanen J (1995) Polychlorinated Dibenzo-p-dioxins and -Furans (PCDDs and PCDFs) in Municipal Waste Landfill Fires. Chemosphere 30 1697... 

Group of isomers with the same carbon skeleton and number of chlorines, e.g., TeCDDs Rat hepatoma cell line Polychlorinated biphenyls Polychlorinated dibcnzo-p-dioxin Polychlorinated dibenzofuran Polychlorinated dibenzo-p-dioxin and -furan Tetrachlorodibenzo-p-dioxin (-furan) Pentachlorodibenzo-p-dioxin ( furan) Hexachlorodibenzo-p-dioxin (-furan) Heptachlorodibenzo-p-dioxin ( furan)... 

At the same time the issues related to the unintentionally produced dioxins and furans, i.e., polychlorinated dibenzo- -dioxins (PCDDs) and PCDFs, attracted public attention in 1983 when investigations revealed that dioxins were detected in the fly ashes from municipal waste incinerators. Therefore, measures to monitor dioxins in the bottom sediment and aquatic animals and plants in the rivers, lakes, marshes and seawaters as well as the atmosphere were initiated in 1986. Investigations were implemented on the actual status of waste incinerators in 1984 and pulp and paper factories in 1990. On the basis of these findings, guidelines and administrative guidance on controlling emissions of dioxin-related chemicals were derived and established. 

Oh, J.R., Hong, S.H., Shim, W. J., Kannan, N., 2005a. A survey of polychlorinated dibenzo-p-dioxins and furans in Korean seafood—A congener-specific approach. Mar. Pollut. Bull. 50, 1121-1127. 

Zhang, Q.H., Jiang, G.B., 2005. Polychlorinated dibenzo-p-dioxins/furans and polychlorinated biphenyls in sediments and aquatic organisms from the Taihu Lake, China. Chemosphere 61, 314-322. 

Table 8.9. Polychlorinated dibenzo-/ -dioxins/ dibenzo-/ -furans (PCDDs/PCDFs) concentrations in bird samples from different countries... 

Ueno, D., Watanabe, M., Subramanian, A., Tanaka, H., Fillmann, G., Lam, P.K., Zheng, G.J., Muchtar, M., Razak, H., Prudente, M., Chung, K.FL, Tanabe, S., 2005. Global pollution monitoring of polychlorinated dibenzo-p-dioxins (PCDDs), furans (PCDFs) and coplanar polychlorinated biphenyls (coplanar PCBs) using skipjack tuna as bioindicator. Environ. Pollut. 136, 303-313. 

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