2,3,7,8-Tetrachlorodibenzo-para-dioxin 2,3,7,8-TCDD

Upper numbering system used for identification of individual PCDD isomers. Lower the isomer 2,3,7,8-tetrachlorodibenzo-para-dioxin (2,3,7,8-TCDD)... 

Dioxin is a term used to describe a large group of chemical compounds having a similar basic structure. The most common subgroup of dioxin compounds (of which there are 75 different varieties) comprises those which include chlorine atoms. A few are toxic the most toxic is 2,3,7,8-tetrachlorodibenzo(para) dioxin (2,3,7,8-TCDD). There are also 135 polychlorinated dibenzofuran corrtpotmds, known as furans. ... 

Precautions for Safe Handling of 2,3,7,8- Tetrachlorodibenzo-para-Dioxin (TCDD) in the Laboratory Dow Chemical 1978. 

Ideo G, Bellati G, Bellobuono A, et al. 1982. Increased urinary D-glucaric acid excretion by children living in an area polluted with 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD). Clin Chim Acta 120 273-283. 

Dioxins are a family of heterocyclic hydrocarbons, mostly poisonous chemical by-products of the manufacture of certain herbicides and bactericides. The most toxic are polychlorinated dibenzo-p-dioxins (CDDs) and dibenzo-furans (CDFs, also called dioxins) [514,515]. Amongst the most dangerous are the isomers of the 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) and 2,3,7,8-tetrachlorodibenzo-furan (TCDF). The former occurs in small amounts in some herbicides and defoliants, including the so-called Agent Orange (a highly toxic herbicide sprayed as a defoliant in chemical warfare) [466]. 

Tetrachlorodibenzo-para-dioxin (TCDD) Tetracycline (internal use)... 

PCBs can be divided into "dioxin-like PCBs" and "nondioxin-like PCBs." Congeners substituted in only the meta and para positions were approximate isostereomers of 2,3,7,8-tetrachlorodibenzo-p-dioxine (TCDD). Toxicological studies confirmed that these nonortho substituted "coplanar" PCBs bind to the Ah Receptor and induce a variety of in vitro and in vivo dioxin-like effects [74,132] and are classified as dioxine-like PCBs. All other PCBs thus fall into the nondioxin-like classification. Maximum dioxine-like activity is obtained for nonortho-PCBs when there is two or more meta, and both para positions are occupied [94,108]. Table 20.4 reports the toxicity of nonortho-PCB congeners expressed in terms of toxicity equivalent factor (TEF) [109,110,134]. TEF is calculated by comparing the toxicity of each congener with that of TCDD (TEF = 1). 

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