Polychlorinated dibenzofurans PCDF

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF), hexachlorbenzene (EICB) and polychlorinated biphenyl (PCB) all of these are (POPs), Stockholm Convention on Persistent Organic Pollutants... 

Many persistent organic pollutants (POPs) are semivolatile compounds which undergo exchange between air and atmospheric particles, soils, and vegetation. Classes of POPs include polychlorinated biphenyls (PCBs), pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs, PCDFs). The distribution of these substances between the particle and gas phases in the atmosphere is a... 

Bocio, A., Domingo, J.L., 2005. Daily intake of polychlorinated dibenzo-p-dioxins/poly-chlorinated dibenzofurans (PCDD/PCDFs) in foodstuffs consumed in Tarragona, Spain A review of recent studies (2001-2003) on human PCDD/PCDF exposure through the diet. Environ. Res. 97, 1-9. 

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/PCDFs)... 

Fiedler H, Cooper KR, Bergek S, et al. 1997. Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) in food samples collected in southern Mississippi, USA. Chemosphere 34(5-7) 1411-1419. 

Polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs/PCDFs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) are now ubiquitous in the environment. Their occurrence in indoor air mainly results from the frequent use of chemical products such as paints, glue, sealants, fire retardants and wood protection agents up to the mid-1980s. Furthermore, PCDDs/PCDFs and PAHs are always formed to some extent during incomplete combustion processes. A list of possible sources is given in Table 1.4-1. 

Persistent or non-degradable environmental chemicals - even those with low volatility - may be dispersed around the globe. Polychlorinated biphenyls (PCB), polychlorinated dibenzodioxins and dibenzofurans (PCDD, PCDF), l,l,l-trichlor-2,2-bis(4-chlorphenyl)-ethan DDT, hexachlorocyclohexane (HCH) and hexachlorobenzene (HCB) have been found in samples from the Arctic and Antarctic and in the tissues of marine animals. Although the open use of many of these chemicals has been prohibited in most industrialized countries, considerable residues still remain in the environment. It is estimated that about 20% of the global production of PCBs (230 000 t/a) persists in the upper layers of the oceans and that a further 7901 are present in the atmosphere (Fiedler and Lau, 1998). Such contamination may accumulate in organisms and have negative effects that go as far as the death of whole populations in ecosystems (Jdrgensen, 1998). 

To date, there has been little published information on the emissions of substances such as volatile organic compounds (VOC), dioxins (polychlorinated dibenzo-dioxins, or PCDD), furans (polychlorinated dibenzofurans, or PCDF) and heavy metals from lime kilns. 

PCBs and PCDDs. In Diarylide Yellow manufacture, the use of formate buffer to enhance pigment transparency for offset ink was discontinued in the nineteen seventies, when it was realized that polychlorinated biphenyls were being produced as an undesirable by-product of the coupling reaction. In Phthalocyanine Blue crude synthesis, the commonly used solvent, trichlorobenzene, was also discontinued in the US, as a potential source of poly-chlorinated biphenyls. More recently, use of chloranil, manufactured from chlorinated phenols, has been discontinued in the synthesis of dioxazine violet crude and sulfonated dioxazine acid dyes, so as to minimize by-product formation of polychlorinated dibenzodioxins and dibenzofurans (PCDDs/PCDFs). A new grade ofhigh purity chloranil is now produced from hydroquinone for dye and pigment manufacture. 

Chlorobenzenes are stable compounds and decompose slowly only under excess heating at high temperatures to release some HCl gas and traces of phosgene. It is possible, under certain limited conditions of incomplete combustion or pyrolysis, to form polychlorinated dibenzo-/)-dioxins (PCDDs) and dibenzofurans (PCDFs) from chlorobenzenes (Cm OROCARBONS and cm OROHYDROCARBONS, toxic aromatics). 

In general, capillary gas chromatography provides enough resolution for most determinations in environmental analysis. Multidimensional gas chromatography has been applied to environmental analysis mainly to solve separation problems for complex groups of compounds. Important applications of GC-GC can therefore be found in the analysis of organic micropollutants, where compounds such as polychlorinated dibenzodioxins (PCDDs) (10), polychlorinated dibenzofurans (PCDFs) (10) and polychlorinated biphenyls (PCBs) (11-15), on account of their similar properties, present serious separation problems. MDGC has also been used to analyse other pollutants in environmental samples (10, 16, 17). 

Broman D, Naf C, Rolfif C, Zebuhr Y, Fry B, Hobbie J. 1992. Using ratios of stable nitrogen isotopes to estimate bioaccumulation and flux of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in two food chains from the northern Baltic. Environ Toxicol Chem 11 331-345. 

Long, G., J. McKinney, and L. Pedersen. 1987. Polychlorinated Dibenzofuran (PCDF) Binding to the Ah Receptor(s) and Associated Enzyme Induction. Theoretical Model based on Molecular Parameters. Quant. Struct.-Act. Relat. 6, 1. 

Mader, B.T., Pankow, J.F. (2003) Vapor pressures of the polychlorinated dibenzodioxins (PCDDs) and the polychlorinated dibenzofurans (PCDFs). Atmos. Environ. 37, 3103-3114. 

C. Rappe and R. Lindahl, "Formation of Polychlorinated Dibenzofurans (PCDFs) and Polychlorinated Dibenzo-p-Dioxins (PCDDs) from the Pyrolysis of Polychlorinated Diphenyl Ethers,"Chemosphere, 2, 351 (1980). 

Loonen, H., J.R. Parsons, and H.A.J. Govers. 1994a. Effect of sediment on the bioaccumulation of a complex mixture of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) by fish. Chemosphere 28 1433-1446. 

Neubert, N., T. Wiesmuller, K. Abraham, R. Krowke, and H. Hagenmaier. 1990. Persistence of various polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs and PCDFs) in hepatic and adipose tissue of marmoset monkeys. Arch. Toxicol. 64 431-442. 

Van den Berg, M., B.L.H.J. Craane, T. Sinnige, S. Van Mourik, S. Dirksen, T. Boudewijn, M. Van der Gaag, I.J. Lutke-Schipholt, B. Spenkelink, and A. Brouwer. 1994. Biochemical and toxic effects of polychlorinated biphenyls (PCBs), dihcnzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in the cormorant (.Phalacrocorax carbo) after in ovo exposure. Environ, Toxicol. Chem. 13 803-816. 

Safe, S. 1990. Polychlorinated biphenyls (PCBs), dibcnzo-p-dioxins PCDDs), dibenzofurans (PCDFs), and related compounds environmental and mechanistic considerations which support the development of toxic equivalency factors (TEFs). Crit. Rev. Toxicol. 21 51-88. 

Because of very high toxicity, ability of delayed action and high stability in the environment, polychlorinated dibenzodioxins (PCDD), dibenzofurans (PCDF) and biphenyls (PCB) are particularly hazardous for people s health if misused for committing acts of terrorism, or under the circumstances of violating the rules of toxic wastes safe storage. 

Dioxins is a generalized name of the large group of polychlorinated dibenzoparadioxins (PCDD) and polychlorinated dibenzofurans (PCDF). 

Figure 19. General formulas of polychlorinated dibenzo-pdioxins, PCDDs (left) and polychlorinated dibenzofurans, PCDFs (right).

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