Editing Polychlorinated dibenzodioxins (section)

==Chemical structure of dibenzo-1,4-dioxins==
[[File:Dibenzo-p-dioxin-numbering-2D-skeletal.png|thumb|200px|The [[skeletal formula]] and [[substituent]] numbering scheme of the parent compound [[dibenzo-1,4-dioxin]]]]

The structure of [[dibenzo-1,4-dioxin]] consists of two [[benzene ring]]s joined by two oxygen bridges. This makes the compound an [[aromatic]] di[[ether]]. The name dioxin formally refers to the central dioxygenated ring, which is stabilized by the two flanking [[benzene ring]]s.

In PCDDs, chlorine atoms are attached to this structure at any of 8 different places on the molecule, at positions 1–4 and 6–9. There are 75 different PCDD [[congener (chemistry)|congeners]] (that is, related dioxin compounds).<ref>[https://www.ncbi.nlm.nih.gov/books/NBK7127/ Nomenclature and physico-chemical properties of PCDDs and PCDFs. In: Dioxins in the Environment: What are the health risks? INSERM Collective Expert Evaluation Reports (2000)]. Ncbi.nlm.nih.gov (2011-03-18). Retrieved on 2011-06-09.</ref>

{|class="wikitable mw-collapsible mw-collapsed"
!number
!formula
!name
!CAS Number
!InChIKey
|-
|PCDD-1
|{{chem2|C12H7ClO2}}
|1-chlorodibenzo-p-dioxin
|39227-53-7
|VGGGRWRBGXENKI-UHFFFAOYSA-N
|-
|PCDD-2
|{{chem2|C12H7ClO2}}
|2-chlorodibenzo-p-dioxin
|39227-54-8
|GIUGGRUEPHPVNR-UHFFFAOYSA-N
|-
|PCDD-12
|{{chem2|C12H6Cl2O2}}
|1,2-dichlorodibenzo-p-dioxin
|54536-18-4
|DFGDMWHUCCHXIF-UHFFFAOYSA-N
|-
|PCDD-13
|{{chem2|C12H6Cl2O2}}
|1,3-dichlorodibenzo-p-dioxin
|50585-39-2
|AZYJYMAKTBXNSX-UHFFFAOYSA-N
|-
|PCDD-14
|{{chem2|C12H6Cl2O2}}
|1,4-dichlorodibenzo-p-dioxin
|54536-19-5
|MBMUPQZSDWVPQU-UHFFFAOYSA-N
|-
|PCDD-16
|{{chem2|C12H6Cl2O2}}
|1,6-dichlorodibenzo-p-dioxin
|38178-38-0
|MAWMBEVNJGEDAD-UHFFFAOYSA-N
|-
|PCDD-17
|{{chem2|C12H6Cl2O2}}
|1,7-dichlorodibenzo-p-dioxin
|82291-26-7
|IJUWLAFPPVRYGY-UHFFFAOYSA-N
|-
|PCDD-18
|{{chem2|C12H6Cl2O2}}
|1,8-dichlorodibenzo-p-dioxin
|82291-27-8
|PLZYIHQBHROTFD-UHFFFAOYSA-N
|-
|PCDD-19
|{{chem2|C12H6Cl2O2}}
|1,9-dichlorodibenzo-p-dioxin
|82291-28-9
|JZDVJXBKJDADAY-UHFFFAOYSA-N
|-
|PCDD-23
|{{chem2|C12H6Cl2O2}}
|2,3-dichlorodibenzo-p-dioxin
|29446-15-9
|YCIYTXRUZSDMRZ-UHFFFAOYSA-N
|-
|PCDD-27
|{{chem2|C12H6Cl2O2}}
|2,7-dichlorodibenzo-p-dioxin
|33857-26-0
|NBFMTHWVRBOVPE-UHFFFAOYSA-N
|-
|PCDD-28
|{{chem2|C12H6Cl2O2}}
|2,8-dichlorodibenzo-p-dioxin
|38964-22-6
|WMWJCKBJUQDYLM-UHFFFAOYSA-N
|-
|PCDD-123
|{{chem2|C12H5Cl3O2}}
|1,2,3-trichlorodibenzo-p-dioxin
|54536-17-3
|SKMFBGZVVNDVFR-UHFFFAOYSA-N
|-
|PCDD-124
|{{chem2|C12H5Cl3O2}}
|1,2,4-trichlorodibenzo-p-dioxin
|39227-58-2
|HRVUKLBFRPWXPJ-UHFFFAOYSA-N
|-
|PCDD-126
|{{chem2|C12H5Cl3O2}}
|1,2,6-trichlorodibenzo-p-dioxin
|69760-96-9
|XQBPVWBIUBCJJO-UHFFFAOYSA-N
|-
|PCDD-127
|{{chem2|C12H5Cl3O2}}
|1,2,7-trichlorodibenzo-p-dioxin
|82291-30-3
|TXJMXDWFPQSYEQ-UHFFFAOYSA-N
|-
|PCDD-128
|{{chem2|C12H5Cl3O2}}
|1,2,8-trichlorodibenzo-p-dioxin
|82291-31-4
|QBEOCKSANJLBAE-UHFFFAOYSA-N
|-
|PCDD-129
|{{chem2|C12H5Cl3O2}}
|1,2,9-trichlorodibenzo-p-dioxin
|82291-32-5
|DQLRDBDQLSIOIX-UHFFFAOYSA-N
|-
|PCDD-136
|{{chem2|C12H5Cl3O2}}
|1,3,6-trichlorodibenzo-p-dioxin
|82291-33-6
|LNPVMVSAUXUGHH-UHFFFAOYSA-N
|-
|PCDD-137
|{{chem2|C12H5Cl3O2}}
|1,3,7-trichlorodibenzo-p-dioxin
|67028-17-5
|RPKWIXFZKMDPMH-UHFFFAOYSA-N
|-
|PCDD-138
|{{chem2|C12H5Cl3O2}}
|1,3,8-trichlorodibenzo-p-dioxin
|82306-61-4
|FJAKCOBYQSEWMT-UHFFFAOYSA-N
|-
|PCDD-139
|{{chem2|C12H5Cl3O2}}
|1,3,9-trichlorodibenzo-p-dioxin
|82306-62-5
|DGDADRUTFAIIQQ-UHFFFAOYSA-N
|-
|PCDD-146
|{{chem2|C12H5Cl3O2}}
|1,4,6-trichlorodibenzo-p-dioxin
|82306-63-6
|UTTYFTWIJLRXKB-UHFFFAOYSA-N
|-
|PCDD-147
|{{chem2|C12H5Cl3O2}}
|1,4,7-trichlorodibenzo-p-dioxin
|82306-64-7
|NBWAQBGJBSYXHV-UHFFFAOYSA-N
|-
|PCDD-178
|{{chem2|C12H5Cl3O2}}
|1,7,8-trichlorodibenzo-p-dioxin
|82306-65-8
|CAPCTZJHYADFNX-UHFFFAOYSA-N
|-
|PCDD-237
|{{chem2|C12H5Cl3O2}}
|2,3,7-trichlorodibenzo-p-dioxin
|33857-28-2
|ZSIZNEVHVVRPFF-UHFFFAOYSA-N
|-
|PCDD-1234
|{{chem2|C12H4Cl4O2}}
|1,2,3,4-tetrachlorodibenzo-p-dioxin
|30746-58-8
|DJHHDLMTUOLVHY-UHFFFAOYSA-N
|-
|PCDD-1236
|{{chem2|C12H4Cl4O2}}
|1,2,3,6-tetrachlorodibenzo-p-dioxin
|71669-25-5
|XEZBZSVTUSXISZ-UHFFFAOYSA-N
|-
|PCDD-1237
|{{chem2|C12H4Cl4O2}}
|1,2,3,7-tetrachlorodibenzo-p-dioxin
|67028-18-6
|SKGXYFVQZVPEFP-UHFFFAOYSA-N
|-
|PCDD-1238
|{{chem2|C12H4Cl4O2}}
|1,2,3,8-tetrachlorodibenzo-p-dioxin
|53555-02-5
|BXKLTNKYLCZOHF-UHFFFAOYSA-N
|-
|PCDD-1239
|{{chem2|C12H4Cl4O2}}
|1,2,3,9-tetrachlorodibenzo-p-dioxin
|71669-26-6
|CMVHZKSHSHQJHS-UHFFFAOYSA-N
|-
|PCDD-1246
|{{chem2|C12H4Cl4O2}}
|1,2,4,6-tetrachlorodibenzo-p-dioxin
|71669-27-7
|KQNBZUDHTCXCNA-UHFFFAOYSA-N
|-
|PCDD-1247
|{{chem2|C12H4Cl4O2}}
|1,2,4,7-tetrachlorodibenzo-p-dioxin
|71669-28-8
|SMPHQCMJQUBTFZ-UHFFFAOYSA-N
|-
|PCDD-1248
|{{chem2|C12H4Cl4O2}}
|1,2,4,8-tetrachlorodibenzo-p-dioxin
|71669-29-9
|XGIKODBWQSAEFQ-UHFFFAOYSA-N
|-
|PCDD-1249
|{{chem2|C12H4Cl4O2}}
|1,2,4,9-tetrachlorodibenzo-p-dioxin
|71665-99-1
|WDAHVJCSSYOALR-UHFFFAOYSA-N
|-
|PCDD-1267
|{{chem2|C12H4Cl4O2}}
|1,2,6,7-tetrachlorodibenzo-p-dioxin
|40581-90-6
|SAMLAWFHXZIRMP-UHFFFAOYSA-N
|-
|PCDD-1268
|{{chem2|C12H4Cl4O2}}
|1,2,6,8-tetrachlorodibenzo-p-dioxin
|67323-56-2
|YYUFYZDSYHKVDP-UHFFFAOYSA-N
|-
|PCDD-1269
|{{chem2|C12H4Cl4O2}}
|1,2,6,9-tetrachlorodibenzo-p-dioxin
|40581-91-7
|ZKMXKYXNLFLUCD-UHFFFAOYSA-N
|-
|PCDD-1278
|{{chem2|C12H4Cl4O2}}
|1,2,7,8-tetrachlorodibenzo-p-dioxin
|34816-53-0
|YDZCLBKUTXYYKS-UHFFFAOYSA-N
|-
|PCDD-1279
|{{chem2|C12H4Cl4O2}}
|1,2,7,9-tetrachlorodibenzo-p-dioxin
|71669-23-3
|QIKHBBZEUNSCAF-UHFFFAOYSA-N
|-
|PCDD-1289
|{{chem2|C12H4Cl4O2}}
|1,2,8,9-tetrachlorodibenzo-p-dioxin
|62470-54-6
|WELWFAGPAZKSBG-UHFFFAOYSA-N
|-
|PCDD-1368
|{{chem2|C12H4Cl4O2}}
|1,3,6,8-tetrachlorodibenzo-p-dioxin
|33423-92-6
|OTQFXRBLGNEOGH-UHFFFAOYSA-N
|-
|PCDD-1369
|{{chem2|C12H4Cl4O2}}
|1,3,6,9-tetrachlorodibenzo-p-dioxin
|71669-24-4
|QAUIRDIJIUMMEP-UHFFFAOYSA-N
|-
|PCDD-1378
|{{chem2|C12H4Cl4O2}}
|1,3,7,8-tetrachlorodibenzo-p-dioxin
|50585-46-1
|VPTDIAYLYJBYQG-UHFFFAOYSA-N
|-
|PCDD-1379
|{{chem2|C12H4Cl4O2}}
|1,3,7,9-tetrachlorodibenzo-p-dioxin
|62470-53-5
|JMGYHLJVDHUACM-UHFFFAOYSA-N
|-
|PCDD-1469
|{{chem2|C12H4Cl4O2}}
|1,4,6,9-tetrachlorodibenzo-p-dioxin
|40581-93-9
|QTIIAIRUSSSOHT-UHFFFAOYSA-N
|-
|PCDD-1478
|{{chem2|C12H4Cl4O2}}
|1,4,7,8-tetrachlorodibenzo-p-dioxin
|40581-94-0
|FCRXUTCUWCJZJI-UHFFFAOYSA-N
|-
|PCDD-2378 (TCDD)
|{{chem2|C12H4Cl4O2}}
|2,3,7,8-tetrachlorodibenzo-p-dioxin
|1746-01-6
|HGUFODBRKLSHSI-UHFFFAOYSA-N
|-
|PCDD-12346
|{{chem2|C12H3Cl5O2}}
|1,2,3,4,6-pentachlorodibenzo-p-dioxin
|67028-19-7
|LNWDBNKKBLRAMH-UHFFFAOYSA-N
|-
|PCDD-12347
|{{chem2|C12H3Cl5O2}}
|1,2,3,4,7-pentachlorodibenzo-p-dioxin
|39227-61-7
|WRNGAZFESPEMCN-UHFFFAOYSA-N
|-
|PCDD-12367
|{{chem2|C12H3Cl5O2}}
|1,2,3,6,7-pentachlorodibenzo-p-dioxin
|71925-15-0
|RLGWDUHOIIWPGN-UHFFFAOYSA-N
|-
|PCDD-12368
|{{chem2|C12H3Cl5O2}}
|1,2,3,6,8-pentachlorodibenzo-p-dioxin
|71925-16-1
|VKDGHBBUEIIEHL-UHFFFAOYSA-N
|-
|PCDD-12369 (PCDD-14678)
|{{chem2|C12H3Cl5O2}}
|1,2,3,6,9-pentachlorodibenzo-p-dioxin
|82291-34-7
|NWKWRHSKKNELND-UHFFFAOYSA-N
|-
|PCDD-12378
|{{chem2|C12H3Cl5O2}}
|1,2,3,7,8-pentachlorodibenzo-p-dioxin
|40321-76-4
|FSPZPQQWDODWAU-UHFFFAOYSA-N
|-
|PCDD-12379 (PCDD-23468)
|{{chem2|C12H3Cl5O2}}
|1,2,3,7,9-pentachlorodibenzo-p-dioxin
|71925-17-2
|UAOYHTXYVWEPIB-UHFFFAOYSA-N
|-
|PCDD-12389 (PCDD-23467)
|{{chem2|C12H3Cl5O2}}
|1,2,3,8,9-pentachlorodibenzo-p-dioxin
|71925-18-3
|VUMZAVNIADYKFC-UHFFFAOYSA-N
|-
|PCDD-12467
|{{chem2|C12H3Cl5O2}}
|1,2,4,6,7-pentachlorodibenzo-p-dioxin
|82291-35-8
|SEKDDGLKEYEVQK-UHFFFAOYSA-N
|-
|PCDD-12468
|{{chem2|C12H3Cl5O2}}
|1,2,4,6,8-pentachlorodibenzo-p-dioxin
|71998-76-0
|SJJWALZHAWITMS-UHFFFAOYSA-N
|-
|PCDD-12469
|{{chem2|C12H3Cl5O2}}
|1,2,4,6,9-pentachlorodibenzo-p-dioxin
|82291-36-9
|GNQVSAMSAKZLKE-UHFFFAOYSA-N
|-
|PCDD-12478
|{{chem2|C12H3Cl5O2}}
|1,2,4,7,8-pentachlorodibenzo-p-dioxin
|58802-08-7
|QUPLGUUISJOUPJ-UHFFFAOYSA-N
|-
|PCDD-12479 (PCDD-13468)
|{{chem2|C12H3Cl5O2}}
|1,2,4,7,9-pentachlorodibenzo-p-dioxin
|82291-37-0
|QLBBXWPVEFJZEC-UHFFFAOYSA-N
|-
|PCDD-12489 (PCDD-13467)
|{{chem2|C12H3Cl5O2}}
|1,2,4,8,9-pentachlorodibenzo-p-dioxin
|82291-38-1
|KLLFLRKEOJCTGC-UHFFFAOYSA-N
|-
|PCDD-123467
|{{chem2|C12H2Cl6O2}}
|1,2,3,4,6,7-hexachlorodibenzo-p-dioxin
|58200-66-1
|NLBQVWJHLWAFGJ-UHFFFAOYSA-N
|-
|PCDD-123468
|{{chem2|C12H2Cl6O2}}
|1,2,3,4,6,8-hexachlorodibenzo-p-dioxin
|58200-67-2
|IMALTUQZEIFHJW-UHFFFAOYSA-N
|-
|PCDD-123469
|{{chem2|C12H2Cl6O2}}
|1,2,3,4,6,9-hexachlorodibenzo-p-dioxin
|58200-68-3
|UDYXCMRDCOVQLG-UHFFFAOYSA-N
|-
|PCDD-123478
|{{chem2|C12H2Cl6O2}}
|1,2,3,4,7,8-hexachlorodibenzo-p-dioxin
|39227-28-6
|WCYYQNSQJHPVMG-UHFFFAOYSA-N
|-
|PCDD-123678
|{{chem2|C12H2Cl6O2}}
|1,2,3,6,7,8-hexachlorodibenzo-p-dioxin
|57653-85-7
|YCLUIPQDHHPDJJ-UHFFFAOYSA-N
|-
|PCDD-123679 (PCDD-124678)
|{{chem2|C12H2Cl6O2}}
|1,2,3,6,7,9-hexachlorodibenzo-p-dioxin
|64461-98-9
|BQOHWGKNRKCEFT-UHFFFAOYSA-N
|-
|PCDD-123689 (PCDD-134678)
|{{chem2|C12H2Cl6O2}}
|1,2,3,6,8,9-hexachlorodibenzo-p-dioxin
|58200-69-4
|GZRQZUFXVFRKBI-UHFFFAOYSA-N
|-
|PCDD-123789 (PCDD-234678)
|{{chem2|C12H2Cl6O2}}
|1,2,3,7,8,9-hexachlorodibenzo-p-dioxin
|19408-74-3
|LGIRBUBHIWTVCK-UHFFFAOYSA-N
|-
|PCDD-124679
|{{chem2|C12H2Cl6O2}}
|1,2,4,6,7,9-hexachlorodibenzo-p-dioxin
|39227-62-8
|BSJDQMWAWFTDGD-UHFFFAOYSA-N
|-
|PCDD-124689 (PCDD-134679)
|{{chem2|C12H2Cl6O2}}
|1,2,4,6,8,9-hexachlorodibenzo-p-dioxin
|58802-09-8
|URELDHWUZUWPIU-UHFFFAOYSA-N
|-
|PCDD-1234678
|{{chem2|C12HCl7O2}}
|1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin
|35822-46-9
|WCLNVRQZUKYVAI-UHFFFAOYSA-N
|-
|PCDD-1234679
|{{chem2|C12HCl7O2}}
|1,2,3,4,6,7,9-heptachlorodibenzo-p-dioxin
|58200-70-7
|KTJJIBIRZGQFQZ-UHFFFAOYSA-N
|-
|PCDD-12346789
|{{chem2|C12Cl8O2}}
|octachlorodibenzo-p-dioxin
|3268-87-9
|FOIBFBMSLDGNHL-UHFFFAOYSA-N
|}

The toxicity of PCDDs depends on the number and positions of the chlorine atoms. Congeners that have chlorine in the 2, 3, 7, and 8 positions have been found to be significantly toxic. In fact, 7 congeners have chlorine atoms in the relevant positions which were considered toxic by the World Health Organization toxic equivalent (WHO-TEQ) scheme.<ref name="pmid16829543">{{cite journal |vauthors=Van den Berg M, Birnbaum LS, Denison M |title=The 2005 World Health Organization reevaluation of human and Mammalian toxic equivalency factors for dioxins and dioxin-like compounds |journal=Toxicol. Sci. |volume=93 |issue=2 |pages=223–41 |year=2006 |pmid=16829543 |doi=10.1093/toxsci/kfl055 |pmc=2290740 |display-authors=etal  }}</ref>