Dibenzofuran: Difference between revisions

{{cleanup|reason = avoid mixing up dibenzofuran with chlorinated derivatives|date=December 2010}}

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| verifiedrevid = 414417988

| ImageName = Skeletal formulashowing numbering convention

| ImageFile1 = Dibenzofuran-3D-balls.png

| ImageName1 = Ball-and-stick model

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| Section1 = {{Chembox Identifiers

| Section2 = {{Chembox Properties

| Appearance = white to pale yellow crystalline powder

| MeltingPt = 81 - 85 °C

| BoilingPt = 285 °C

| Section3 = {{Chembox Hazards

| Autoignition =

| RPhrases = {{R51/53}}

| SPhrases = {{S24/25}} {{S29}} {{S61}}

| Section4 = {{Chembox Related

| OtherCpds = [[Furan]]<br />[[Benzofuran]]<br />[[Dibenzodioxin]]<br />[[Dibenzothiophene]]<br />[[Carbazole]]<br />[[Polyozellin]] (compound with a ''kernel'' with two dibenzofurans that share the same benzene ring)

'''Dibenzofuran''', is a [[heterocyclic]] [[organic compound]] with the [[chemical structure]] shown at right. It is an [[aromatic compound]] that has two [[benzene]] rings fused to one [[furan]] ring in the middle. All of the numbered [[carbon]] atoms have a [[hydrogen]] atom bonded to each of them (not shown in the image). Dibenzofuran is an [[aromatic]] [[ether]] having the chemical formula C₁₂H₈O.

==Dibenzofurans==

'''Dibenzofurans''' can also refer to [[polychlorinated dibenzofurans]] (PCDFs), a family of organic compounds which are [[polyhalogenated compound]]s which have atom or group substitutions made for the hydrogens on any of the numbered carbon atoms in the dibenzofuran structure. For example, 2,3,7,8-tetrachlorodibenzofuran (TCDF) has [[chlorine]] atoms substituted for each of the hydrogens on the number 2, 3, 7, and 8 carbons (see structure below). Polychlorinated dibenzofurans are very [[toxicity|toxic]] chemicals with properties and chemical structures similar to [[polychlorinated dibenzodioxins]], often simply called [[Dioxins and dioxin-like compounds|dioxin]].

[[Image:2,3,7,8-Tetrachlorodibenzofuran.png|frame|left|Chemical structure of TCDF (2,3,7,8-tetrachlorodibenzofuran)]]

The dibenzofuran TCDF (2,3,7,8-tetrachlorodibenzofuran) is the dibenzofuran analog of the [[polychlorinated dibenzodioxins|polychlorinated dibenzodioxin]] TCDD ([[2,3,7,8-tetrachlorodibenzodioxin]]), the poison released in the [[Seveso disaster]].

==Environmental and health consequences==

'''Probable places of origin'''

It is a white crystal-like solid created from production of coal tar.<ref>http://www.epa.gov/epawaste/hazard/wastemin/minimize/factshts/dibenzof.pdf</ref> It is used as an insecticide, in the production of PVC, industrial bleaching and incineration.

'''Production and Producers''': Dibenzofuran is recovered from a wash oil fraction of coal tar that boils between 275 °C and 290 °C. Redistillation separates dibenzofuran from acenaphthene, which boils at a lower temperature. Crystallization of the redistilled fraction then produces technically pure dibenzofuran.<ref>Elvers, B., Hawkins, S., Ravenscroft, M., Rounsaville, J.F. & Schulz, G., eds. (1989) Ullmann’s Encyclopedia of Industrial Chemistry. 5th ed., vol A12, NY, VCH Publishers, pp130-131</ref> Typical wood preservative creosote is approximately 3.5% dibenzofuran. Dibenzofuran occurs at levels of 0.19-1.50 wt % of dry tar in commercial coal tars.<ref>ATSDR (1990) Toxicological Profile for Creosote (TP-90-09). Atlanta, GA, [[Agency for Toxic Substances and Disease Registry]], pp 1-4, 9, 63-68</ref> It also is a by-product of smoking and affects both the smoker and second hand smokers.<ref name=niehs>http://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/Dibenzofuran.pdf</ref>

'''Pathways of exposure'''

''Occupational exposure'' to dibenzofuran may occur through inhalation and dermal contact, particularly at sites where coal tar, coal tar derivatives, and creosote are produced and used.<ref>U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database).</ref><ref>Polychlorinated dibenzo-p-dioxin and dibenzofuran concentrations in serum samples of workers at intermittently burning municipal waste incinerators in Japan. Occupational and Environmental Medicine 2002;59:362-368</ref>

''General Population Exposure'': Fish and dairy intake also have been studied to be related with body burden of dibenzofuran in pregnant women.<ref>Associations of diet with body burden of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs): observations on pregnant women from central Taiwan. Food Addit Contam. 2007 Jul;24(7):784-91</ref> Consumption of contaminated water and food are the primary sources of exposure.<ref>Congener-Specific Levels of Dioxins and Dibenzofurans in U.S. Food and Estimated Daily Dioxin Toxic Equivalent Intake. The National Institute of Environmental Health Sciences (NIEHS).</ref>

'''Excretion''':

Dibenzofuran is excreted 22% the daily intake of dioxins from meals is excreted from feces and 29% from sebum.<ref>Balance of Intake and Excretion of 20 Congeners of Polychlorinated Dibenzo-p-dioxin, Polychlorinated Dibenzofuran and Coplanar Polychlorinated Biphenyl in Healthy Japanese Men. J Health Sci. VOL.47; NO.2; PAGE.145-154(2001)</ref>

'''Regulatory Status''':

Dibenzofuran is cited in the Clean Air Act 1990 Amendments -Hazardous Air Pollutants as a volatile hazardous air pollutant of potential concern. The Superfund Amendment Reauthorization Act (SARA) Section 110 placed dibenzofuran on the revised [[Agency for Toxic Substances and Disease Registry]] (ATSDR) priority list of hazardous substances to be the subject of a toxicological profile. The listing was based on the substance’s frequency of occurrence at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List sites, its toxicity, and/or its potential for human exposure. Dibenzofuran is also listed in the Massachusetts Substance List for Right-to-Know Law, the New Jersey Department of Health Hazard Right-to-Know Program Hazardous Substance List, and the Pennsylvania Department of Labor and Industry Hazardous Substance List. California’s Air Toxics “Hot Spots” List (Assembly Bill).<ref name=niehs/>

'''Testing process'''

No medical test exists to identify dibenzofuran.<ref>New Jersey Department of Health and Senior Services. Hazardous Substance

Fact Sheet: Dibenzofuran - http://nj.gov/health/eoh/rtkweb/documents/fs/2230.pdf</ref> But if symptoms of eye, nose, throat or skin irritation occurs after exposure (accidentally / workplace) medical attention is recommended. EPA uses High Performance Liquid Chromatography (HPLC) to monitor samples.<ref>http://www.osha.gov/dts/chemicalsampling/data/CH_231985.html</ref><ref>Determination of OCDD and OCDF in soils and biological samples by GC/ECD. Waste testing and quality assurance. 3rd Vol. ASTM STP 1075. D.Friedman. American society for testing and materials.</ref>

==References==

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[[Category:Aromatic compounds]]

[[Category:Dibenzofurans]]

[[de:Dibenzofuran]]

[[es:Dibenzofurano]]

[[fr:Dibenzofurane]]

[[it:Dibenzofurano]]

[[ja:ジベンゾフラン]]

[[pl:Dibenzofuran]]

[[pt:Dibenzofurano]]