Editing Polychlorinated dibenzodioxins (section)

==Toxicity==
[[File:Dioxin-3D-vdW.png|thumb|220px|[[Space-filling model]] of 2,3,7,8-tetrachlorodibenzodioxin]]

[[2,3,7,8-Tetrachlorodibenzodioxin]] (TCDD) is considered the most toxic of the [[congener (chemistry)|congener]]s (for the mechanism of action, see [[2,3,7,8-Tetrachlorodibenzodioxin]] and [[Aryl hydrocarbon receptor]]). Other dioxin congeners including PCDFs and PCBs with dioxin-like toxicity, are given a toxicity rating from 0 to 1, where TCDD = 1 (see [[Dioxins and dioxin-like compounds]]). This toxicity rating is called the Toxic Equivalence Factor concept, or [[Toxic equivalency factor|TEF]]. TEFs are consensus values and, because of the strong species dependence for toxicity, are listed separately for mammals, fish, and birds. TEFs for mammalian species are generally applicable to human risk calculations. The TEFs have been developed from detailed assessment of literature data to facilitate both risk assessment and regulatory control.<ref name="pmid16829543"/> Many other compounds may also have dioxin-like properties, particularly non-ortho [[Polychlorinated biphenyl|PCBs]], one of which has a TEF as high as 0.1.

The total dioxin toxic equivalence (TEQ) value expresses the toxicity as if the mixture were pure TCDD. The TEQ approach and current TEFs have been adopted internationally as the most appropriate way to estimate the potential health risks of mixture of dioxins. Recent data suggest that this type of simple scaling factor may not be the most appropriate treatment for complex mixtures of dioxins; both transfer from the source and absorption and elimination vary among different congeners, and the TEF value is not able to accurately reflect this.<ref>Tuomisto, J. The toxic equivalency principle and its application in dioxin risk assessment. In: R. Pohjanvirta (editor): The AH Receptor in Biology and Toxicology. Wiley, 2011. {{ISBN|978-0-470-60182-2}}.</ref>

Dioxins and other [[persistent organic pollutant]]s (POPs) are subject to the [[Stockholm Convention]]. The [[treaty]] obliges signatories to take measures to eliminate where possible, and minimize where not possible to eliminate, all sources of dioxin.