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PCDDs/PCDFs occurrence

Properties of PCDEs, including physicochemical ones, are not well known as the literature reviews of PCDEs have shown [4, 11,40,46]. PCDEs resemble PCBs structurally and in their chemical and physical properties, which, like PCDDs, PCDFs, and related compounds, are known to be stable and resistant to breakdown by heat, hydrolysis, bases, and acids. PCBs are also quite stable to oxidation under moderate conditions [3], but there is not much data about PCDEs concerning their stability. There is some evidence that PCDEs are resistant to bases and acids and the occurrence of PCDEs in the environment indicates that PCDEs are persistent and bioaccumulating compounds. The study of Firestone et al. [37] already showed that PCDEs are quite stable, since PCDEs could be measured in chlorophenol extracts after sulfuric acid treatment. Tetra- and octachlorinated PCDE congeners were later proven resistant in treatment with... [Pg.168]

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. [Pg.45]

Petty, J.D., D.L. Stalling, L.M. Smith, and J.L. Johnson. 1983. Occurrence and potential impact of PCDF s and PCDD s in aquatic ecosystems. Pages 96-102 in D.D. Hemphill (ed.). Trace Substances in Environmental Health XVII. Univ. Missouri, Columbia. [Pg.1065]

Toxicokinetics of PCBs in rodents were altered when administered in mixtures (de Jongh et al. 1992). PCBs 153, 156, and 169 produced biphasic elimination patterns in mice when administered in combinations, but single-phase elimination when administered alone. Elimination of all PCBs was more rapid after coadministration. Mixtures of PCBs 153 and 156 raised EROD activity and lengthened retention of each congener in liver however, a mixture of PCB 153 and 169 lowered EROD activity (de Jongh et al. 1992). Selected PCBs of low acute toxicity may increase the toxicity of compounds such as 2,3,7,8-TCDD (Bimbaum et al. 1985). Thus, PCB 153 or 157 at sublethal dosages (20 to 80 mg/kg BW) did not produce cleft palate deformities in mouse embryos. But a mixture of PCB 157 and 2,3,7,8-TCDD produced a tenfold increase in the incidence of palate deformities that were expected of 2,3,7,8-TCDD alone palate deformities did not increase with a mixture of PCB 153 and 2,3,7,8-TCDD. The widespread environmental occurrence of PCB-PCDD and PCB-PCDF combinations suggests a need for further evaluation of the mechanism of this interaction (Bimbaum et al. 1985). [Pg.1312]

E. Fly ash. Olie et al. reported in 1977 on the occurrence of PCDDs and PCDFs in fly ash and flue gas samples from municipal incinerators in the Netherlands (UjO. No quantitative data were given in this report, but Buser and Bosshardt made a... [Pg.328]

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). [Pg.41]

Apart from classical organochlorines, not much literature is available on the occurrence of other PTS compounds like butyltins, polybromin-ated diphenyl ethers, etc. in Indian human breast milk. Indian Council of Medical Research (ICMR) in their news bulletin of the year 2004 has indicated that they could detect PCDDs and PCDFs in the human milk samples collected from Ahmedabad, Vadodara and Surat cities (http //icmr.nic.in). They have found that the TEQs of dioxins and related compounds in their samples ranged from about 2 to 16 pg g 1 lipid weight of human milk. [Pg.469]

Amendola G, Bama D, Blosser R, et al. 1989. The occurrence and fate of PCDDs and PCDFs in five bleached kraft pulp and paper mills. Chemosphere 18 1181-1188. [Pg.584]

Beck H, Eckart K, Mathar W, et al. 1988b. Occurrence of PCDD and PCDF in different kinds of paper. Chemosphere 17 51-57. [Pg.588]

Kitunen VH, Salkinoja-Salonen MS. 1989. Occurrence of PCDDs and PCDFs in pulp and board products. Chemosphere 19 721-726. [Pg.641]

Petty JD, Stalling DL, Smith LM, et al. 1983. Occurrence and potential impact of PCDFs and PCDDs in aquatic ecosystems. Trace Subst Environ Health 17 96-102. [Pg.670]

Rotard W, Christmann W, Lattner A, et al. 1987. Occurrence of PCDD and PCDF in motor oils, refined oils and contaminated soils. Chemosphere 16 1847-1849. [Pg.679]

Swerev M, Ballschmiter K. 1989. Pattern analysis of PCDDs and PCDFs in environmental samples as an approach to an occurrence/source correlation. Chemosphere 18 609-616. [Pg.693]

After PCDEs were detected in a fly ash from a municipal waste incinerator in Finland [36], the occurrence of PCDEs in combustion wastes has not been studied much. PCDEs could be formed during incomplete combustion by condensation from chlorophenols as has been indicated for PCDDs [54], but de novo synthesis is also possible [55]. The formation of chlorinated compounds is always possible during combustion in the presence of organic material and chloride. The formation of PCDEs de novo in combustion has been described in the literature review of Kurz s thesis [4]. Briefly, diphenyl can be formed from the phenoxy radical and benzene which in turn can be formed from alkene radicals. If the formed molecule does not already contain chlorine, chlorination of diphenyl ether can occur, e.g., in the presence of HCl. It has been suggested, however, that PCDEs, in contrast to PCDDs and PCDFs, are not formed to a great extent de novo on solid surfaces or in the gas phase in thermal processes during metal reclamation processes [56]. When PCDEs were analyzed in emission samples of a metal reclamation plant in Finland, all PCDEs were below 4 ng nr3. [Pg.168]

The occurrence of polychlorinated aromatic sulfur compounds in the environment has been reported during the last decade. PCDDs and PCDFs are formed by different chemical,photochemical and enzymatic reactions [10], It is possible that PCDTs and PCTAs are formed by chemical processes similar to those of the formation of PCDFs and PCDDs. Until now, PCDTs have been analyzed in stack gas and fly ash samples, in sediments, pulp mill effluents, and in some aquatic organisms. Some PCTA congeners have been observed in pulp mill effluents, stack gas, and soil and compost samples. The compound 2468-TeCDT has been found to accumulate from environmentally contaminated sediments to sandworms, clams, and grass shrimp. Accumulation factors have been calculated [11]. [Pg.290]

Van der Velde EG, Marsman JA, De Jong AP, et al. 1994. Analysis and occurrence of toxie planar PCBs, PCDDs and PCDFs in milk by use of carbosphere activated carbon. Chemosphere 28(4) 693-702. [Pg.827]

Wastes containing PAHs may be effectively destroyed by various incineration processes as mentioned briefly in the above section. Weber et al. (2001) have studied the mechanisms of formation of polychlorinated diben-zofurans (PCDF), polychlorinated biphenyls (PCB), polychlorinated naphthalenes (PCN) and polychlorinated benzenes (PCBz) from the degradation of PAHs in two types of incinerators, the stoker type- and the fluidized bed incinerators. Their studies have revealed the occurrence of a sequence of steps, such as the cleavage of C-C bond in the PAHs, chlorination at these cleaved positions, further chlorination or oxygen insertion at the ortho positions to the chlorine atoms in the intermediate chlorinated species. A perylene structure in soot is proposed as the basis for the observed PCDF pattern in the fluidized bed incinerators. Polychlorinated dibenzo-dioxins (PCDD) and the polychlorinated... [Pg.526]

TCDD. The widespread environmental occurrence of PCB-PCDD and PCB-PCDF combinations suggests a need for further evaluation of the mechanism of this interaction. [Pg.638]

The occurrence and severity of the toxic symptoms noted above are species, strain, sex and age-dependent and not all the responses, with the possible exception of enzyme induction, are observed in any single animal species. It is also apparent that other halogenated aromatics, including the polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) elicit comparable species-dependent biologic and toxic effects and it has been proposed that these toxins act through a comparable mechanism which involves initial binding to the cytosolic aryl hydrocarbon (Ah) receptor protein present in target tissues.33,40-42... [Pg.52]


See other pages where PCDDs/PCDFs occurrence is mentioned: [Pg.28]    [Pg.308]    [Pg.33]    [Pg.55]    [Pg.988]    [Pg.64]    [Pg.38]    [Pg.325]    [Pg.345]    [Pg.54]    [Pg.787]   
See also in sourсe #XX -- [ Pg.46 ]




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