208 2,3,7,8-Tetrachlorodibenzofuran Chlorinated dibenzofurans (CDFs) are a family of chemical that contain one to eight chlorine atoms attached to the carbon atoms of the parent chemical, dibenzofuran. The CDF family contains 135 individual compounds with varying damaging health and environmental effects; those 2,3,7,8-substitued being particularly harmful. Most CDFs are produced in very small amounts as unwanted impurities after use of chlorinated compounds. Only a few of these 135 compounds have been produced and their properties (color, smell, taste, and toxicity) studied. (L952) 51207-31-9 39929 C12H4Cl4O 303.901630 Colorless crystals. 227°C 6.92e-07 mg/mL at 26 °C [FRIESEN,KJ & WEBSTER,GRB (1990)] Inhalation (L952) ; dermal (L952) ; oral (L952) Halogenated dibenzofurans (PCDFs and PBDFs) bind the aryl hydrocarbon receptor (AhR), which increases its ability to activate transcription in the XRE (xenobiotic resoponse element) promoter region. Specifically AhR binds to the PCDF, translocates it to the nucleus and together with hydrocarbon nuclear translocator (ARNT) and xenobiotic responsive element (XRE) increases the expression of CYP1A1 and aryl hydrocarbon hydroxylase (CYP1B1). AhR signaling also increseases conversion of arachidonic acid to prostanoids via cyclooxygenase-2, alters Wnt/beta-catenin signaling downregulating Sox9 and alters signaling by receptors for inflammatory cytokines. AhR signalling also alters proteasomal degradation of steroid hormone receptors, alters cellular UVB stress response and changes the differentiation of certain T-cell subsets. The resulting AhR mediated activation and alteration leads to body weight loss, cancer and thymic atrophy (characteristic of immune and endocrine disruption) which are common toxic responses to PCDFs and related toxic halogenated aryl hydrocarbons. No information on the metabolism of dibenzofuran in mammalian organisms was found in the available literature. The bacteria Sphingomonas, Brevibacterium, Terrabacter, and Staphylococcus auricularis degrade dibenzofuran to 2,2',3-trihydroxybiphenyl via dibenzofuran 4,4a-dioxygenase. (L952) 3, not classifiable as to its carcinogenicity to humans. (L135) CDFs are created from production of coal tar and during incineration. They are used as insecticides, in the production of PVC, and in industrial bleaching. (L952) CDFs cause vomiting and diarrhea, anemia, more frequent lung infections, numbness and other effects on the nervous system, and mild changes in the liver. However, there were no permanent liver changes or definite liver damage found in people who ingested CDFs. (L952) Skin and eye irritations, especially severe acne, darkened skin color, and swollen eyelids with discharge are the most obvious health effects of the CDF poisoning. (L952) 2009-03-06T18:58:17Z 2014-12-24T20:21:19Z C18104 C014211 2,3,7,8-Tetrachlorodibenzofuran 8003 true ClC1=C(Cl)C=C2C(OC3=CC(Cl)=C(Cl)C=C23)=C1 C12H4Cl4O InChI=1S/C12H4Cl4O/c13-7-1-5-6-2-8(14)10(16)4-12(6)17-11(5)3-9(7)15/h1-4H InChIKey=KSMVNVHUTQZITP-UHFFFAOYSA-N 305.972 303.901625578 Exogenous Solid CHEMBL136710 36507