Dioxin
<p><b >Dioxins</b> and <b >dioxin-like compounds</b> (DLC)<sup id="cite_ref-synopsis_0-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Dioxins_and_dioxin-like_compounds#cite_note-synopsis-0" >[1]</a></sup> are by-products of various industrial processes, and are commonly regarded as highly <a href="http://en.wikipedia.org/wiki/Toxic" title="Toxic" class="mw-redirect" >toxic</a> <a href="http://en.wikipedia.org/wiki/Chemical_compound" title="Chemical compound" >compounds</a> that are <a href="http://en.wikipedia.org/wiki/Environmental_pollutant" title="Environmental pollutant" class="mw-redirect" >environmental pollutants</a> and <a href="http://en.wikipedia.org/wiki/Persistent_organic_pollutant" title="Persistent organic pollutant" >persistent organic pollutants</a> (POPs).<sup id="cite_ref-dangers_1-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Dioxins_and_dioxin-like_compounds#cite_note-dangers-1" >[2]</a></sup> They include:<sup id="cite_ref-synopsis_0-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Dioxins_and_dioxin-like_compounds#cite_note-synopsis-0" >[1]</a></sup><sup id="cite_ref-Pohja_2-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Dioxins_and_dioxin-like_compounds#cite_note-Pohja-2" >[3]</a></sup>
<sup id="cite_ref-Pohja_2-0" class="reference" > </sup></p>
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<li ><a href="http://en.wikipedia.org/wiki/Polychlorinated_dibenzodioxins" title="Polychlorinated dibenzodioxins" >Polychlorinated dibenzo<i>-p-</i>dioxins</a> (PCDDs), or simply, <a href="http://en.wikipedia.org/wiki/Obsessive-compulsive_disorder" title="Obsessive-compulsive disorder" class="mw-redirect" >but</a> inaccurately, dioxins. Technically PCDDs are derivatives of<a href="http://en.wikipedia.org/wiki/Dibenzodioxin" title="Dibenzodioxin" class="mw-redirect" >dibenzo<i>-p-</i>dioxin</a>. There are 75 PCDDs, and seven of them are specifically toxic.</li>
<li ><a href="http://en.wikipedia.org/wiki/Polychlorinated_dibenzofurans" title="Polychlorinated dibenzofurans" >Polychlorinated dibenzofurans</a> (PCDFs), or simply furans. Technically PCDFs are derivatives of <a href="http://en.wikipedia.org/wiki/Dibenzofuran" title="Dibenzofuran" >dibenzofuran</a>. There are 135 congeners (derivatives differing only in the number and location of chlorine atoms). Whilst they strictly speaking are not dioxins, ten of them have "dioxin-like" properties.</li>
<li ><a href="http://en.wikipedia.org/wiki/Polychlorinated_biphenyl" title="Polychlorinated biphenyl" >Polychlorinated biphenyls</a> (PCBs), which also are not dioxins, but twelve of them have "dioxin-like" properties. Under certain conditions PCBs may form more toxic dibenzofurans through partial oxidation.</li>
<li >Finally, dioxin may refer to <a href="http://en.wikipedia.org/wiki/1,4-Dioxin" title="1,4-Dioxin" >dioxin</a> proper, the basic chemical unit of the more complex dioxins. This simple compound is not persistent and has no PCDD-like toxicity.</li>
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The endocrine disrupting activity of dioxins is thought to occur as a down-stream function of AH receptor activation, with thyroid status in particular being a sensitive marker of exposure. It is important to note that TCDD, along with the other PCDDs, PCDFs and dioxin-like coplanar PCBs are not direct agonists or antagonists of hormones, and are not active in assays which directly screen for these activities such as <a href="http://en.wikipedia.org/w/index.php?title=ER-CALUX&action=edit&redlink=1" class="new" title="ER-CALUX (page does not exist)" >ER-CALUX</a> and <a href="http://en.wikipedia.org/w/index.php?title=AR-CALUX&action=edit&redlink=1" class="new" title="AR-CALUX (page does not exist)" >AR-CALUX</a>. These compounds have also not been shown to have any direct <a href="http://en.wikipedia.org/wiki/Mutagenic" title="Mutagenic" class="mw-redirect" >mutagenic</a> or <a href="http://en.wikipedia.org/wiki/Genotoxic" title="Genotoxic" class="mw-redirect" >genotoxic</a> activity.<sup id="cite_ref-Dragan_9-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Dioxins_and_dioxin-like_compounds#cite_note-Dragan-9" >[10]</a></sup> Their main action in causing cancer is cancer promotion. A mixture of PCBs such as <a href="http://en.wikipedia.org/wiki/Aroclor" title="Aroclor" class="mw-redirect" >Aroclor</a> may contain PCB compounds which are known <a href="http://en.wikipedia.org/wiki/Estrogen_receptor" title="Estrogen receptor" >estrogen agonists</a>, but on the other hand are not classified as dioxin-like in terms of toxicity. Mutagenic effects have been established for some lower chlorinated chemicals such as 3-chlorodibenzofuran, which is neither persistent nor an AH receptor agonist.<sup id="cite_ref-10" class="reference" ><a href="http://en.wikipedia.org/wiki/Dioxins_and_dioxin-like_compounds#cite_note-10" >[11]</a></sup></p>