Dioxin-like polychlorinated biphenyls

EXPOSURE PATHWAYS OF DIOXINS AND DIOXIN-LIKE POLYCHLORINATED BIPHENYLS TO HUMAN... 

Senthilkumar, K., Iseki, N., Hayama, S., Nakanishi, J., Masunaga, S., 2002. Polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in livers of birds from Japan. Arch. Environ. Contam. Toxicol. 42, 244-255. 

Helm, P.A., Bidleman, T.F. (2003) Current combustion-related sources contribute to polychlorinated naphthalene and dioxin-like polychlorinated biphenyl levels and profiles in air in Toronto, Canada. Environmental Science and Technology, 37(6) 1075-1082. 

JISC (2008). Japanese Industrial Standards Committee JIS K0312 2005, 2008 Method for determination of tetra- through octachlorodihenzo-p-dioxins, tetra- through octachlorodibenzofurans and dioxin-like polychlorinated biphenyls in industrial water and waste water, 2005 2008. 

Schoeters G, Hoogenboom R. Contamination of free-range chicken eggs with dioxins and dioxin-like polychlorinated biphenyls. Mol Nutr Food Res 2006 50(10) 908 14. 

Kor) tar, P. Danielsson, C. Leonards, P.E.G. Haglund, P. de Boer, J. Brinkman, U.Th. Separation of seventeen 2,3,7,8-substimted polychlorinated dibenzo-p-dioxins and 12 dioxin-like polychlorinated biphenyls by comprehensive two-dimensional gas chromatography with electron-capture detection. J. Chromatogr. A, 2004,1038, 189-199. 

M.T. (2008) Comparison of gas chromatography-ion-trap tandem mass spectrometry systems for the determination of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls. / Chromatogr. A, 1186, 302-311. 

The monitoring of food and feed stufffor the presence of polychlorinated dibenzo-/r-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and the dioxin-like polychlorinated biphenyls (dl-PCBs) can be performed with screening and confirmatory methods. 

Zeiger M, Haag R, Hockel J, Schrenk D, Schmitz HJ Inducing effects of dioxin-like polychlorinated biphenyls on CYPIA in the human hepatoblastoma cell line HepG2, the rat hepatoma cell line H4IIE, and rat primary hepatocytes comparison of relative potencies. Toxicol Sci 2001, 63 65-73. 

For halogenated aromatic hydrocarbons like polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and polychlorinated dibenzo-p-dioxins (PCDDs) the binding to the aryl hydrocarbon (Ah) receptor regulates their toxicity [89]. The Ah receptor controls the induction of one of the cytochrome P450 enzymes in the liver. Toxic responses such as thymic atrophy, iveight loss, immu-notoxicity and acute lethality are associated ivith the relative affinity of PCBs, PCDFs and PCDDs for the Ah receptor [89]. The quantitative structure-activity relationship (QSAR) models predicting the affinity of the halogenated aromatic hydrocarbons ivith the Ah receptor describe the electron acceptor capability as well as the hydrophobicity and polarizability of the chemicals [89[. 

Halides and, in particular, chlorinated compounds are often present in toxic wastes and some of them, like polychlorinated biphenyls or dioxins, are extremely stable under oxidation conditions. Various chlorinated model compounds serve as model feeds in SCWO investigations. 

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. 

In addition to the chemicals included on the other lists, the CDC also included heavy metals such as arsenic, lead, and mercury volatile solvents such as benzene, chloroform, and bromoform decomposition products such as dioxins and furans polychlorinated biphenyls (PCBs) flammable industrial gases and liquids such as gasoline and propane explosives and oxidizers and all persistent and nonpersistent pesticides. Agents included in this volume are limited to those that are most likely to pose an acute toxicity hazard. 

This approach was initially developed to estimate the potential toxicity of mixtures of polychlorinated dibenzo- -dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated dioxin-like biphenyls (PCBs). Over the years, a number of different TEF systems for PCDDs, PCDFs and PCBs have been used. A system was internationally agreed upon at a WHO Consultation in 1997 (WHO-TEF) as published by Van den Berg et al. (1998). A WHO update has been published recently (Van den Berg et al. 2006) (Table 10.3). 

Although this public health statement will focus on CDDs, it is important to note that CDDs are found in the environment together with other structurally related chlorinated chemicals, such as chlorinated dibenzofurans (CDFs) and polychlorinated biphenyls (PCBs). Therefore, people are generally exposed to mixtures of CDDs and other classes of toxicologically and structurally similar compounds. 2,3,7,8-TCDD is one of the most toxic and extensively studied of the CDDs and serves as a prototype for the toxicologically relevant or dioxin-like CDDs. Based on results from animal studies, scientists have learned that they can express the toxicity of dioxin-like CDDs as a fraction of the toxicity attributed to 2,3,7,8-TCDD. For example, the toxicity of dioxin-like CDDs can be half or one tenth or any fraction of that of 2,3,7,8-TCDD. Scientists call that fraction a Toxic Equivalent Factor (TEF). More information on TEFs can be found in Section 2.5. 

EPA. 1997c. Addition of dioxin and dioxin-like compounds modification of polychlorinated biphenyls (PCBs) listing toxic chemical release reporting community right-to-know. U. S. Environmental Protection Agency. Federal Register. 62 FR 24887. 

Like dioxin and DDT, these chemicals are associated in the public mind with pollution and nasty chemicals. What are they PCB is an abbreviation for polychlorinated biphenyls this means the chemical biphenyl has various numbers of chlorine atoms attached to it. There are 200 possible substances, known as congeners, with the number of chlorine atoms ranging from one to ten in the molecule. The PCBs that are usually manufactured are a mixture of products with various numbers of chlorine atoms in the molecules. PBBs are similar chemicals called polybromi-nated biphenyls, in which various numbers of bromine atoms are attached to biphenyl. 

Giesy, J.P., Kannan, K. (1998). Dioxin-like and non-dioxin-like toxic effects of polychlorinated biphenyls (PCBs) implications for risk assessment. Crit. Rev. Toxicol. 28 511-69. 

---