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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.
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.
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.
Possible side effects include itchiness and skin rash, [5] and in rare cases hearing loss. [5] It is relatively broad spectrum, being effective against both Gram-negative and Gram-positive bacteria. [2] The combination is available over the counter in the US and Canada. [5]
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.
(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 ...
1,4-Dioxin (also referred as dioxin or p-dioxin) is a heterocyclic, organic, non-aromatic [2] compound with the chemical formula C 4 H 4 O 2. There is an isomeric form of 1,4-dioxin, 1,2-dioxin (or o -dioxin). 1,2-Dioxin is very unstable due to its peroxide -like characteristics.
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the reference chemical to which the toxicity of other dioxins and DLCs are compared. TCDD is the most toxic DLC known. Other dioxins and DLCs are assigned a scaling factor, or TEF, in comparison to TCDD. TCDD has a TEF of 1.0. Sometimes PCB 126 is also used as a reference chemical, with a TEF of 0.1.