• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.172-173
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• 2003

There are growing concerns about human health effects of dioxin and dioxin like compounds such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). Earlier studies recognized that 2.3.7.8-tetrachloro dibenzo-p-dioxin (TCDD) and structually related dioxin like compounds invoke a number of common toxic responses that are mediated through a high-affinity cytosolic receptor protein, the AhR.(omitted)

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.9-9
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• 2003

There are growing concerns about human health effects of dioxin and dioxin like compounds such as polychlorinated dibenzo-p-dioxins (PCDDS), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs), Earlier studies recognized that 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) and structually related dioxin like compounds invoke a number of common toxic responses that are mediated through a high-affinity cytosolic receptor protein, the AhR. Based on studies that Indicate th pivotal role of AhR in mediating most, if not all, of the dioxin toxicity, TCDD equivalency factor (TEF) approach was developed. This approach allowed the expression of toxic potential of a complex mixture as one integrated parameter, the toxic equivalency (TEQ) value.

• Analytical Science and Technology
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• v.8 no.4
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• pp.821-827
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• 1995

Polychlorodibenzo-p-dioxins(PCDDs) have been prepared by microsacale pyrolysis of trichlorophenates. During the pyrolysis reaction, dechlorinated dibenzo-p-dioxins were also formed by the thermolysis of PCDDs. The dechlorination pathways of PCDDs were suggested in this reaction. The identification of these products was performed using capillary column gas chromatography-mass spectrometry.

• Journal of Environmental Science International
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• v.18 no.7
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• pp.803-810
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• 2009

Concentrations of dioxins, furans and dioxin-like polychlorinated biphenyls (DL-PCBs) were determined in crucian carp collected from eight locations mainly along the Nakdong River during 2004. Total dioxin concentrations which include concentrations of dioxins, furans and DL-PCBs ranged from 0.053 to 0.614 pg WHO-TEQ $g^{-1}$ wet wt. with a mean of $0.342{\pm}0.213$ pg WHO-TEQ $g^{-1}$ wet wt. The proportions of dioxins, furans and DL-PCBs to total dioxin TEQ were 4%, 12% and 84%, respectively. The results suggest that concentrations of dioxin-like polychlorinated biphenyls should be determined when total dioxin TEQ accumulated in freshwater fish is investigated.

• Environmental Analysis Health and Toxicology
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• v.14 no.1_2
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• pp.65-73
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• 1999

Dioxins refer to a family of chemicals comprising 75 polychlorinated dibenzo-p-dioxin (PCDD) and 135 polychlorinated dibenzo-p-furan (PCDF) congeners, which may cause skin disorder, human immune system disruption, birth defects, severe hormonal imbalance, and cancer. The effects of exposure of dioxin-like compounds such as PCBs are mediated by binding to the aryl hydrocarbon receptor (AHR), which is a ligand-activated transcription factor. To grasp physicochemical factors affecting human toxicity of dioxins, six geometrical and topological indices, eleven thermodynamic variables, and quantum mechanical descriptors including ESP (electrostatic potential) were analyzed using QSAR and semi-empirical AM1 method. Planar dioxins with high lipophilicity and large surface tension show the probability that negative electrostatic potential in the lateral oxygen may make hydrogen bonding with DNA bases to be a carcinogen.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.43-46
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• 2003

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.792-796
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• 2003

Polychlorinated dibenzo-p-dioxins (PCDDs) are extremely toxic and persistent environmental pollutants. Their chemical reactivities and other physicochemical/biological properties show a strong dependence on the chlorination pattern. With increasing the number of chlorines, dioxin congeners become more electronegative and gain higher electron affinities. The vertical electron affinities (VEA) are related with the LUMO energies of neutral molecules. LUMO energies of all PCDD congeners were calculated at the B3LYP/6-31G** level and those of some selected congeners at the level of B3LYP/6-311G**//B3LYP/6-31G** and B3LYP/cc-pvtz/ /B3LYP/6-31G**. The total energies of neutral and anionic species for dibenzo-p-dioxins (DD), 1469-TCDD, 2378-TCDD, and OCDD were calculated at the level of B3LYP/6-31G**, B3LYP/aug-cc-pvdz, and B3LYP/ aug-cc-pvtz//B3LYP/6-31G**. By using the four congeners with D2h symmetry as reference molecules, we could estimate VEA (B3LYP/aug-cc-pvdz) of 75 PCDD congeners based on the linear correlations between LUMO energy and VEA (B3LYP/6-31G**) and between VEA (B3LYP/6-31G**) and VEA (B3LYP/aug-ccpvtz// B3LYP/6-31G**). Results show that all PCDDs with the number of Cl ≥ 3 have positive electron affinities. The PCDD electron affinity values provided in this work can be a useful data set in understanding the congener-specific reactivities of dioxins in various environmental media.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.145-145
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• 2002

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a prototype and the most potent chemical of the polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (dioxins). A variety of studies on the toxic effects of dioxin and related compounds have been conducted internationally since 1990.(omitted)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.225-228
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• 1999

The formation of dioxin (term used here to refer to both polychlorinated dibenzo-p-dioxins, PCDDS, and dibenzofurans, PCBFs) in combustion processes is of concern because of the extreme toxicities of some of these compounds and because of their resistance to degradation in the environment. The number and location of chlorine substituents differentiate dioxin homologues and isomers, respectively. There are a total of 75 PCDD congeners and 135 PCDF congeners.(omitted)

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2001.05a
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• pp.137-137
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• 2001

It is it well known fact that the most relevant toxic emissions such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-1ike polychlorinated biphenyls (PCBs) are produced from incinerators. Induction of cytochrome P450IA1 catalyzed 7-ethoxyresorufin 0-deethylase (EROD) activity in mammalian cell culture (EROD-microbioassay) is a selective and sensitive parameter used for the quantification of dioxin-like compounds. (omitted)