Editing Coal tar (section)

== Uses ==
=== Medicinal ===
Coal tar is on the [[World Health Organization's List of Essential Medicines]], the most effective and safe medicines needed in a [[health system]].<ref name="WHO21st"/> Coal tar is generally available as a [[generic medication]] and [[over the counter]].<ref name="Ric2015" />

Coal tar is used in medicated [[shampoo]], [[Wrights Coal Tar Soap|soap]] and [[ointment]]. It demonstrates [[antifungal]], [[anti-inflammatory]], [[antipruritic|anti-itch]], and [[antiparasitic]] properties.<ref name="Mai2011" /> It may be applied topically as a treatment for [[dandruff]] and [[psoriasis]], and to kill and repel [[head lice]].<ref name="WHO2008"/> It may be used in combination with [[ultraviolet light therapy]].<ref name="WHO2008" />

Coal tar may be used in two forms: crude coal tar ({{langx|la|pix carbonis}}) or a coal tar solution ({{langx|la|liquor picis carbonis, LPC}}) also known as liquor carbonis detergens (LCD).<ref name="Mai2011"/><ref name="Pharmacyaus">{{cite book|title=Clinical pharmacy : a practical approach - Society of Hospital Pharmacists of Australia| vauthors = Hughes J, Donnelly R, James-Chatgilaou G |date=2001|publisher=Macmillan Publishers Australia|isbn=9780732980290|location=South Yarra|page=114}}</ref><ref name="paghdal">{{cite journal | vauthors = Paghdal KV, Schwartz RA | title = Topical tar: back to the future | journal = Journal of the American Academy of Dermatology | volume = 61 | issue = 2 | pages = 294–302 | date = August 2009 | pmid = 19185953 | doi = 10.1016/j.jaad.2008.11.024 }}</ref> Named brands include Denorex, Balnetar, Psoriasin, Tegrin, T/Gel, and Neutar. When used in the extemporaneous preparation of topical medications, it is supplied in the form of coal tar topical solution [[United States Pharmacopeia|USP]], which consists of a [[Mass concentration (chemistry)|20% w/v]] solution of coal tar in [[ethanol|alcohol]], with an additional 5% w/v of [[polysorbate 80]]&nbsp;USP; this must then be diluted in an ointment base, such as [[petrolatum]].

=== Construction ===
{{Main|Sealcoat}}

Coal tar was a component of the first sealed roads. In its original development by [[Edgar Purnell Hooley]], [[Tarmacadam|tarmac]] was tar covered with granite chips. Later the filler used was industrial [[slag]]. Today, petroleum derived binders and sealers are more commonly used. These sealers are used to extend the life and reduce maintenance cost associated with [[Asphalt concrete|asphalt]] pavements, primarily in asphalt road paving, car parks and walkways.{{citation needed|date=April 2021}}

Coal tar is incorporated into some parking-lot [[sealcoat]] products used to protect the structural integrity of the underlying pavement.<ref name="fs20113010">{{cite web| vauthors = Mahler BJ, Van Metre PC | url = http://pubs.usgs.gov/fs/2011/3010/| title = Coal-Tar-Based Pavement Sealcoat, Polycyclic Aromatic Hydrocarbons (PAHs), and Environmental Health| publisher = U.S. Geological Survey Fact Sheet| date = 2 February 2011| access-date = 8 March 2013| url-status = live| archive-url = https://web.archive.org/web/20130328042236/http://pubs.usgs.gov/fs/2011/3010/| archive-date = 2013-03-28}}</ref> Sealcoat products that are coal-tar based typically contain 20 to 35 percent coal-tar pitch.<ref name="fs20113010"/> Research<ref name=lakes>{{cite journal | vauthors = Van Metre PC, Mahler BJ | title = Contribution of PAHs from coal-tar pavement sealcoat and other sources to 40 U.S. lakes | journal = The Science of the Total Environment | volume = 409 | issue = 2 | pages = 334–44 | date = December 2010 | pmid = 21112613 | doi = 10.1016/j.scitotenv.2010.08.014 | bibcode = 2010ScTEn.409..334V }}</ref> shows it is used throughout the [[United States of America]], however several areas have banned its use in sealcoat products,<ref name=austin>{{cite web| url = http://www.austintexas.gov/sites/default/files/files/Watershed/coaltar_ordinance.pdf| title = City of Austin Ordinance 20051117-070| date = 17 November 2005| access-date = 8 March 2013| url-status = live| archive-url = https://web.archive.org/web/20130531014726/http://austintexas.gov/sites/default/files/files/Watershed/coaltar_ordinance.pdf| archive-date = 2013-05-31}}</ref><ref name=dc>{{cite web| title = District Bans Coal-Tar Pavement Products| url = http://newsroom.dc.gov/show.aspx/agency/ddoe/section/2/release/17479| date = 26 June 2009| access-date = 8 March 2013| url-status = live| archive-url = https://web.archive.org/web/20121226213006/http://newsroom.dc.gov/show.aspx/agency/ddoe/section/2/release/17479| archive-date = 2012-12-26}}</ref><ref name=dane>{{cite web| publisher = Dane County Office of Lakes and Watersheds| url = http://pdf.countyofdane.com/ordinances/ORD080.pdf| title = Ordinance 80 : Establishing Regulations on Coal Tar Sealcoat Products Application and Sale| date = 1 July 2007| access-date = 8 March 2013| url-status = live| archive-url = https://web.archive.org/web/20110824044232/http://pdf.countyofdane.com/ordinances/ORD080.pdf| archive-date = 2011-08-24}}</ref> including the District of Columbia; the city of Austin, Texas; Dane County, Wisconsin; the state of Washington; and several municipalities in Minnesota and others.<ref>{{cite web| title = Coal Tar Free America&nbsp;– Bans| url = http://coaltarfreeamerica.blogspot.com/p/bans.html| access-date = 8 March 2013| url-status = live| archive-url = https://web.archive.org/web/20141006095421/http://coaltarfreeamerica.blogspot.com/p/bans.html| archive-date = 2014-10-06}}</ref><ref name="EESI">{{cite conference| conference-url = http://www.eesi.org/pahs-increasing-urban-us-lakes-14-apr-2011| conference = PAHs Increasing in Urban U.S. Lakes| url = http://files.eesi.org/mahler_041411.pdf| title = Causes of Increasing Concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) in U.S. Lakes| vauthors = Mahler BJ | publisher = Environmental and Energy Study Institute| date = 14 April 2011| access-date = 8 March 2013| url-status = dead| archive-url = https://web.archive.org/web/20111005105420/http://files.eesi.org/mahler_041411.pdf| archive-date = 5 October 2011}}</ref>

=== Industry ===
In modern times, coal tar is mostly traded as fuel and an application for tar, such as roofing. The total value of the trade in coal tar is around US$20 billion each year.<ref>{{cite web | url=https://oec.world/en/profile/hs/coal-tar-oil | title=Coal Tar Oil &#124; OEC }}</ref>

* As a fuel.

* In the manufacture of paints, synthetic dyes (notably [[tartrazine]]/Yellow #5), and photographic materials.<ref>{{cite book | vauthors = Hathaway AW |title=Remediation of Former Manufactured Gas Plants and Other Coal-Tar Sites |date=2011 |publisher=Taylor & Francis Group}}</ref>

* For heating or to fire [[boilers]]. Like most heavy oils, it must be heated before it will flow easily.<ref>{{cite book | vauthors = Speight JG | chapter = Coal gasification processes for synthetic liquid fuel production | veditors = Luque R, Speight JG | title = Gasification for Synthetic Fuel Production | series = Woodhead Publishing Series in Energy |date=2015 |pages=201–220 (212) | publisher = Woodhead | isbn = 978-0-85709-802-3 |doi=10.1016/B978-0-85709-802-3.00009-6 | quote = 9.5.1 Coal tar chemicals: Coal tar is a black or dark brown liquid or a high-viscosity semi-solid that is one of the by-products formed when coal is carbonized. Coal tars are complex and variable mixtures of polycyclic aromatic hydrocarbons (PAHs), phenols, and heterocyclic compounds. Because of its flammable composition, coal tar is often used for fire boilers in order to create heat. They must be heated before any heavy oil flows easily.}}</ref>
* As a source of [[carbon black]].<ref>{{cite web |title=Market Study: Carbon Black |url=http://www.ceresana.com/en/market-studies/chemicals/carbon-black/ |access-date=2013-04-26 |publisher=Ceresana}}</ref>

* As a binder in manufacturing [[graphite]]; a considerable portion of the materials in "green blocks" is coke oven volatiles (COV). During the baking process of the green blocks as a part of commercial graphite production, most of the coal tar binders are vaporised and are generally burned in an incinerator to prevent release into the atmosphere, as COV and coal tar can be injurious to health.<ref>{{Cite web|date=2018-11-02|title=CDC - Immediately Dangerous to Life or Health Concentrations (IDLH): Coal tar pitch volatiles - NIOSH Publications and Products|url=https://www.cdc.gov/niosh/idlh/65996932.html|access-date=2021-10-05|website=www.cdc.gov|language=en-us}}</ref><ref>{{Cite book| vauthors = Speight JG |title=Asphalt materials science and technology|date=2015|publisher=Elsevier Science|isbn=978-0-12-800501-9|location=Amsterdam|page=60|oclc=922698102}}</ref>

* As a main component of the [[electrode paste]] used in electric [[arc furnace]]s. Coal tar pitch act as the binder for solid filler that can be either coke or calcined anthracite, forming electrode paste, also widely known as Söderberg electrode paste.<ref>{{Cite journal | vauthors = Beukes JP, Roos H, Shoko L, Van Zyl PG, Neomagus HW, Strydom CA, Dawson NF |date= June 2013 |title=The use of thermomechanical analysis to characterise Söderberg electrode paste raw materials |journal=Minerals Engineering |language=en |volume=46-47 |pages=167–176 |doi=10.1016/j.mineng.2013.04.016 |issn=0892-6875|doi-access=free |bibcode= 2013MiEng..46..167B }}</ref>

* As a feed stock for higher-value fractions, such as [[naphtha]], [[creosote]] and [[Pitch (resin)|pitch]].  In the [[coal gas]] era, companies [[distill]]ed coal tar to separate these out, leading to the discovery of many industrial chemicals. 

:Some British companies included:<ref>{{Cite journal| vauthors = Ronalds BF |date=2019|title=Bonnington Chemical Works (1822-1878): Pioneer Coal Tar Company|journal=International Journal for the History of Engineering & Technology|volume=89|issue=1–2|pages=73–91|doi=10.1080/17581206.2020.1787807|s2cid=221115202}}</ref><ref>{{cite web | vauthors = Smith M |url= http://www.igg.org.uk/gansg/12-linind/tardis.htm |title=GANSG&nbsp;– Coal Tar Distillers |publisher=Igg.org.uk |access-date=8 March 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130619153801/http://www.igg.org.uk/gansg/12-linind/tardis.htm |archive-date=2013-06-19 }}</ref>

** [[Bonnington Chemical Works]]
** British Tar Products
** Lancashire Tar Distillers
** Midland Tar Distillers
** [[Newton, Chambers & Company]] (owners of Izal brand disinfectant)
** [[Samuel Sadler|Sadlers Chemicals]]