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Dioxins build up primarily in fatty tissues over time (bioaccumulation), so even small exposures may eventually reach dangerous levels. In 1994, the US EPA reported that dioxins are a probable carcinogen, but noted that non-cancer effects (reproduction and sexual development, immune system) may pose a greater threat to human health.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a polychlorinated dibenzo-p-dioxin (sometimes shortened, though inaccurately, to simply 'dioxin') [3] with the chemical formula C 12 H 4 Cl 4 O 2. Pure TCDD is a colorless solid with no distinguishable odor at room temperature.
They activate the aryl hydrocarbon receptor (AH receptor), albeit with very different binding affinities, leading to high differences in toxicity and other effects. They include: [1] [3] [4] Polychlorinated dibenzo-p-dioxins (PCDDs), or simply dioxins. PCDDs are derivatives of dibenzo-p-dioxin.
Dibenzo-1,4-dioxin, also dibenzodioxin or dibenzo-p-dioxin (dibenzo-para-dioxin), is a polycyclic heterocyclic organic compound in which two benzene rings are connected by a 1,4-dioxin ring. Its molecular formula is C 12 H 8 O 2. The two oxygen atoms occupy opposite (para-) positions in the six-membered dioxin ring.
The half-lives of Hexachlorodibenzo-p-dioxin and octachlorodibenzo-p-dioxin were estimated to be 3.5 and 2 years, respectively. [6] The effects of chlorodibenzo-p-dioxin exposure was examined in rats over a 13-week period. Hepatic accumulation was associated with alterations of several biochemical parameters.
(for details see Dioxins and dioxin-like compounds). Chlorinated pesticides can also contain impurities of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and their precursors. "Precursor formation of PCDD/Fs can also be mediated by ultraviolet light (UV)" from sun (OCDD mostly). Changes in congeners ratio after UV exposition suggest that ...
Dibenzo-1,4-dioxin, also known as dibenzodioxin or dibenzo-p-dioxin (molecular formula C 12 H 8 O 2), in which two benzene rings are connected through two oxygen atoms. That is the parent compound of the dioxins (see next in which the dioxins comprise a key part of the class).
[2] [3] For general population the most important source is food of animal origin like with other dioxin-like compounds. [ 4 ] [ 5 ] [ 6 ] The most relevant congener is 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PCDF) which is more toxic and based on relative toxicity more prevalent than other PCDFs.