Editing Chlorine (section)

==Hazards==
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Chlorine is a toxic gas that attacks the respiratory system, eyes, and skin.<ref>{{Cite web|url=http://www.bt.cdc.gov/agent/chlorine/basics/facts.asp |title=Facts About Chlorine |website=www.bt.cdc.gov |access-date=2016-04-12 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20160423193302/http://www.bt.cdc.gov/agent/chlorine/basics/facts.asp |archive-date=2016-04-23 }}</ref> Because it is denser than air, it tends to accumulate at the bottom of poorly ventilated spaces. Chlorine gas is a strong oxidizer, which may react with flammable materials.<ref name="msds-cl">{{cite web|url=http://www.westlake.com/datasheets/MSDS_Chlorine.pdf |archive-url=https://web.archive.org/web/20070926183417/http://www.westlake.com/datasheets/MSDS_Chlorine.pdf |archive-date= 2007-09-26 |title=Chlorine MSDS|date=1997-10-23}}</ref><ref>{{cite web|url=http://cameochemicals.noaa.gov/chemical/2862|title=Chlorine|author=NOAA Office of Response and Restoration, US GOV|work=noaa.gov|access-date=25 August 2015|url-status=live|archive-url=https://web.archive.org/web/20151015212302/http://cameochemicals.noaa.gov/chemical/2862|archive-date=15 October 2015}}</ref>

Chlorine is detectable with measuring devices in concentrations as low as 0.2 parts per million (ppm), and by smell at 3&nbsp;ppm. Coughing and vomiting may occur at 30&nbsp;ppm and lung damage at 60&nbsp;ppm. About 1000&nbsp;ppm can be fatal after a few deep breaths of the gas.<ref name="Greenwood792" /> The [[IDLH]] (immediately dangerous to life and health) concentration is 10&nbsp;ppm.<ref name="NIOSH">{{PGCH|0115}}</ref> Breathing lower concentrations can aggravate the respiratory system and exposure to the gas can irritate the eyes.<ref name="tox">{{cite journal|journal = Environmental Research|volume = 85|issue = 2|date = 2001 |doi = 10.1006/enrs.2000.4110 |title = The Toxicology of Chlorine|author = Winder, Chris|pages = 105–14|pmid = 11161660|bibcode = 2001ER.....85..105W }}</ref> When chlorine is inhaled at concentrations greater than 30&nbsp;ppm, it reacts with water within the lungs, producing [[hydrochloric acid]] (HCl) and [[hypochlorous acid]] (HOCl).

When used at specified levels for water disinfection, the reaction of chlorine with water is not a major concern for human health. Other materials present in the water may generate [[disinfection by-products]] that are associated with negative effects on human health.<ref>{{cite web|url=http://news.aces.illinois.edu/news/whats-your-water-disinfectants-create-toxic-products|title=What's in your Water?: Disinfectants Create Toxic By-products|date=2009-03-31|work=ACES News|publisher=College of Agricultural, Consumer and Environmental Sciences – University of Illinois at Urbana-Champaign|access-date=2009-03-31|url-status=live|archive-url=https://web.archive.org/web/20140903101530/http://news.aces.illinois.edu/news/whats-your-water-disinfectants-create-toxic-products|archive-date=2014-09-03}}</ref><ref>{{cite journal |doi=10.1016/j.mrrev.2007.09.001 |title=Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research |date=2007 |last1=Richardson |first1=Susan D. |last2=Plewa |first2=Michael J. |last3=Wagner |first3=Elizabeth D. |last4=Schoeny |first4=Rita |last5=DeMarini |first5=David M. |journal=Mutation Research/Reviews in Mutation Research |volume=636 |pages=178–242 |pmid=17980649 |issue=1–3|bibcode=2007MRRMR.636..178R }}</ref>

In the United States, the [[Occupational Safety and Health Administration]] (OSHA) has set the [[permissible exposure limit]] for elemental chlorine at 1&nbsp;ppm, or 3&nbsp;mg/m<sup>3</sup>. The [[National Institute for Occupational Safety and Health]] has designated a [[recommended exposure limit]] of 0.5&nbsp;ppm over 15 minutes.<ref name="NIOSH" />

In the home, accidents occur when hypochlorite bleach solutions come into contact with certain acidic drain-cleaners to produce chlorine gas.<ref>{{Cite web|url=https://www.forbes.com/sites/alexberezow/2013/11/04/why-you-should-never-mix-different-drain-cleaners/#1d08c8fc32c8|title=Why You Should Never Mix Different Drain Cleaners|last=Berezow|first=Alex|website=Forbes|access-date=2016-04-12|url-status=live|archive-url=https://web.archive.org/web/20160425184357/http://www.forbes.com/sites/alexberezow/2013/11/04/why-you-should-never-mix-different-drain-cleaners/#1d08c8fc32c8|archive-date=2016-04-25}}</ref> Hypochlorite bleach (a popular [[laundry]] additive) combined with [[ammonia]] (another popular laundry additive) produces [[chloramines]], another toxic group of chemicals.<ref>{{Cite web|url=http://www.doh.wa.gov/YouandYourFamily/HealthyHome/Contaminants/BleachMixingDangers|title=Bleach Mixing Dangers : Washington State Dept. of Health|website=www.doh.wa.gov|access-date=2016-04-12|url-status=live|archive-url=https://web.archive.org/web/20160414074554/http://www.doh.wa.gov/YouandYourFamily/HealthyHome/Contaminants/BleachMixingDangers|archive-date=2016-04-14}}</ref>

=== Chlorine-induced cracking in structural materials ===
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[[File:Chlorine attack1.jpg|thumb|Chlorine "attack" on an acetal resin plumbing joint resulting from a fractured acetal joint in a water supply system which started at an [[injection molding]] defect in the joint and slowly grew until the part failed. The fracture surface shows iron and calcium salts that were deposited in the leaking joint from the water supply before failure and are the indirect result of the chlorine attack.]]

Chlorine is widely used for purifying water, especially potable water supplies and water used in swimming pools. Several catastrophic collapses of swimming pool ceilings have occurred from chlorine-induced [[stress corrosion cracking]] of [[stainless steel]] suspension rods.<ref>{{Cite book|url=https://books.google.com/books?id=cEmq232h1zcC&pg=PA148|page=148|title=Corrosion of steel in concrete: prevention, diagnosis, repair|author=Bertolini, Luca|author2=Elsener, Bernhard|author3=Pedeferri, Pietro|author4=Polder, Rob B.|publisher=Wiley-VCH|date=2004|isbn=978-3-527-30800-2|access-date=2020-05-06|archive-date=2023-12-30|archive-url=https://web.archive.org/web/20231230134102/https://books.google.com/books?id=cEmq232h1zcC&pg=PA148#v=onepage&q&f=false|url-status=live}}</ref> Some [[polymer]]s are also sensitive to attack, including [[acetal resin]] and [[polybutene]]. Both materials were used in hot and cold water domestic plumbing, and [[stress corrosion cracking]] caused widespread failures in the US in the 1980s and 1990s.<ref>{{cite book|author=Lewis, P.R.|title=Polymer Product Failure|url=https://books.google.com/books?id=SFm8rKotSaUC&pg=PA19|access-date=2011-04-30|date=1 January 2000|publisher=iSmithers Rapra Publishing|isbn=978-1-85957-192-7|pages=19–|url-status=live|archive-url=https://web.archive.org/web/20130510041524/http://books.google.com/books?id=SFm8rKotSaUC&pg=PA19|archive-date=10 May 2013}}</ref>

=== Chlorine-iron fire ===
The element [[iron]] can combine with chlorine at high temperatures in a strong exothermic reaction, creating a ''chlorine-iron fire''.<ref name="bayerdatasheet2008">{{cite web|url=https://tecci.bayer.de/io-tra-pro/emea/de/docId-2857612/Chlorine.pdf |title=Chlorine: Product Datasheet |publisher=Bayer MaterialScience AG |date=2008-04-21 |access-date=2013-12-17 |url-status=dead |archive-url=https://web.archive.org/web/20120915114003/https://tecci.bayer.de/io-tra-pro/emea/de/docId-2857612/Chlorine.pdf |archive-date=September 15, 2012 }}</ref><ref name="sanders2004">{{Cite book | isbn = 978-0-7506-7749-3 | title = Chemical Process Safety: Learning from Case Histories, 3rd Revised edition | last1 = Sanders | first1 = Roy E. | year = 2004 | publisher = Elsevier Science & Technology | location = Oxford | page = 92 }}</ref> Chlorine-iron fires are a risk in chemical process plants, where much of the pipework that carries chlorine gas is made of steel.<ref name="bayerdatasheet2008" /><ref name="sanders2004" />