Polychlorinated dibenzodioxins

Food and Agricultural Organization of the United Nations, World Health Organization, Joint FAO-WHO Expert Committee on Food Additives, 57th Meeting, Rome, June 5-14,2001. Summary and Conclusions. Annex 4 Contaminants. 5. Polychlorinated Dibenzodioxins, Polychlorinated Dibenzofurans, and Coplanar Polychlorinated Biphenyls, http //www.who.int/ pcs/jecfa/Summary57-corr.pdf. pp. 24-40. 

Liquid-crystalline stationary phases are used to analyze a great number of chemical compounds such as polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzodioxins, polychlorinated dibenzofur-ans, polychlorinated naphthalenes, terpenes, steroids, pesticides, pheromones, etc. 

Because PCB molecules have two benzene rings or 12 carbon atoms as well as some chlorine atoms, they wUl bum at high temperatures when ignited. The main danger from a PCB fire is not the PCB itself, but the formation of extremely toxic byproducts of combustion, such as polychlorinated dibenzodioxins, polychlorinated dibenzofurans, and hydrogen chloride gas, which often produce immediate respiratory effect. The formation of dioxins and furans... 

SW-846, is used to measure emissions of semivolatile principal organic constituents. Method 0010 is designed to determine destruction and removal efficiency (DRE) of POHCs from incineration systems. The method involves a modification of the EPA Method 5 sampling train and may be used to determine particulate emission rates from stationary sources. The method is applied to semivolatile compounds, including polychlorinated biphenyls (PCBs), chlorinated dibenzodioxins and dibenzofurans, polycyclic organic matter, and other semivolatile organic compounds. 

Ecological danger of polychlorinated dibenzodioxines and dibenzofurans 97MI26, 97MI45, 98MI33, 98MI34. 

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). 

Dioxins are prominent members of the class of polychlorinated hydrocarbons that also includes diben-zofuran, biphenyls and others. Dioxins are highly toxic environmental contaminants. Like others small planar xenobiotics, some dioxins bind with high affinity to the arylhydrocarbon (Ah) receptor. Dioxins activate the receptor over a long time period, but are themselves poor substrates for the enzymes which are induced via the Ah-receptor. These properties of the dioxins and related xenobiotics may be important for the toxicity of these compounds. Dioxins like 2,3,7,8-tetrachloro-p-dibenzodioxin can cause persistent dermatosis, like chloracne and may have other neurotoxic, immunotoxic and carcinogenic effects. 

The complete elimination of functional groups is often an undesirable side reaction in organic synthesis, but on the other hand it is a possibility for the recycling of environmentally harmful compounds, for example phenols and haloarenes such as polychlorinated dibenzodioxins (PCDDs or dioxins ). For example, aryl chlorides can be effectively dechlorinated with Pd(0) NPs in tetra-butylammonium salts with almost quantitative conversions also after 19 runs (entry H, Table 1.4) [96]. On the other hand, a C-0 bond cleavage reaction also seems suitable for the fragmentation of sugar-based biomass such as cellulose or cello-biose in that way, sugar monomers and bioalcohol can be derived from renewable resources (entry F, Table 1.4) [164]. 

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

Huckins, J.N., D.L. Stalling, and W.A. Smith. 1978. Foam-charcoal chromatography for analysis of polychlorinated dibenzodioxins in herbicide orange. Jour. Assoc. Off. Anal. Chem. 61 32-38. 

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. 

Investigations have shown that plants on thermal treatment of solid domestic waste represent the source of polychlorinated dibenzodioxins and biphenyls. In this connection, it is necessary to conduct further investigations of their emission and determination of all the range of PCDD, PCDF and PCB... 

Abstract Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs),... 

Polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs), in contrast to other chlorinated chemicals, have never been commercially manufactured nor are of any benefit or known use. PCDD/Fs are ubiquitous contaminants, which are released as byproducts of incomplete combustion or as impurities in chemical processes, and that their levels in the environment are increasing. 

Figure 10.4 The structures of polychlorinated dibenzodioxins and polychlorinated dibenzofurans...

Beger, R.D., Buzatu, D.A. and Wilkes, J.G. (2002) Combining NMR spectral and structural data to form models of polychlorinated dibenzodioxins, dibenzofurans, and biphenyls binding to the AhR. Journal of Computer-Aided Molecular Design, 16, 727-740. 

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