{{Distinguish|1,4-Dioxin}} {{Redirect|Dioxane|other uses|Dioxane (compounds)}} {{Use dmy dates|date=May 2020}} {{Chembox | Watchedfields = changed |verifiedrevid = 477206315 |ImageFileL1 = 1-4-Dioxane.svg |ImageClassL1 = skin-invert |ImageNameL1 = Chemical structure of dioxane |ImageSizeL1 = 90px |ImageFileR1 = 1,4-Dioxane-3D-balls.png |ImageClassR1 = bg-transparent |ImageSizeR1 = 130px |ImageNameR1 = 1,4-dioxane |ImageFile2 = 1,4-dioxane.png |ImageSize2 = 150px |PIN = 1,4-Dioxane |SystematicName= 1,4-Dioxacyclohexane |OtherNames = [1,4]Dioxane<br />''p''-Dioxane<br />[6]-crown-2<br />Diethylene dioxide<br />Diethylene ether<br />Dioxane solvent |Section1 = {{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChEBI_Ref = {{ebicite|correct|EBI}} |ChEBI = 47032 |ChemSpiderID = 29015 | KEGG_Ref = {{keggcite|correct|kegg}} |KEGG = C14440 |InChI = 1/C4H8O2/c1-2-6-4-3-5-1/h1-4H2 |InChIKey = RYHBNJHYFVUHQT-UHFFFAOYAN | ChEMBL_Ref = {{ebicite|correct|EBI}} |ChEMBL = 453716 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} |StdInChI = 1S/C4H8O2/c1-2-6-4-3-5-1/h1-4H2 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |StdInChIKey = RYHBNJHYFVUHQT-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} |CASNo = 123-91-1 |EINECS = 204-661-8 | UNII_Ref = {{fdacite|correct|FDA}} |UNII = J8A3S10O7S | DrugBank_Ref = {{drugbankcite|correct|drugbank}} |DrugBank = DB03316 | PubChem = 31275 | RTECS = JG8225000 | UNNumber = 1165 | Beilstein = 102551 |SMILES = O1CCOCC1 }} |Section2 = {{Chembox Properties |C = 4 |H = 8 |O = 2 |MeltingPtC = 11.8 |BoilingPtC = 101.1 |Density = 1.033&nbsp;g/mL |Solubility = Miscible |Appearance = Colorless liquid<ref name=PGCH /> |Odor = Mild, [[diethyl ether]]-like<ref name=PGCH /> |VaporPressure = 29&nbsp;mmHg (20&nbsp;°C)<ref name=PGCH /> | MagSus = −52.16·10{{sup|−6}}&nbsp;cm{{sup|3}}/mol }} |Section4 = {{Chembox Thermochemistry |DeltaHf = −354&nbsp;kJ/mol |DeltaHc = −2363&nbsp;kJ/mol |Entropy = 196.6&nbsp;J/K·mol }} |Section7 = {{Chembox Hazards |NFPA-H = 2 |NFPA-F = 3 |NFPA-R = 1 | GHSPictograms = {{GHS02}}{{GHS07}}{{GHS08}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|225|302|305|315|319|332|336|351|370|372|373}} | PPhrases = {{P-phrases|201|202|210|233|240|241|242|243|260|261|264|270|271|280|281|302+352|303+361+353|304+312|304+340|305+351+338|307+311|308+313|312|314|321|332+313|337+313|362|370+378|403+233|403+235|405|501}} |FlashPtC = 12 | AutoignitionPtC = 180 |PEL = TWA 100&nbsp;ppm (360&nbsp;mg/m{{sup|3}}) [skin]<ref name=PGCH>{{PGCH|0237}}</ref> |ExploLimits = 2.0–22%<ref name=PGCH /> |IDLH = Ca [500&nbsp;ppm]<ref name=PGCH /> |REL = Ca C 1&nbsp;ppm (3.6&nbsp;mg/m{{sup|3}}) [30-minute]<ref name=PGCH /> |MainHazards = Suspected human carcinogen<ref name=PGCH /> |LC50 = {{Unbulleted list | 10,109&nbsp;ppm (mouse, 2&nbsp;hr) | 12,568 ppm (rat, 2 hr)<ref name=IDLH>{{IDLH|123911|Dioxane}}</ref> }} |LCLo = 1000–3000&nbsp;ppm (guinea pig, 3&nbsp;hr)<br /> 12,022&nbsp;ppm (cat, 7&nbsp;hr)<br /> 2085&nbsp;ppm (mouse, 8&nbsp;hr)<ref name=IDLH /> |LD50 = {{Unbulleted list | 5&nbsp;g/kg (mouse, oral) | 4&nbsp;g/kg (rat, oral) | 3&nbsp;g/kg (guinea pig, oral) | 7.6&nbsp;g/kg (rabbit, dermal) }} }} |Section8 = {{Chembox Related |Related_ref = |OtherAnions = |OtherCations = |OtherFunction = |OtherFunction_label = |OtherCompounds = [[Oxane]]<br />[[Trioxane]] }} }}

'''1,4-Dioxane''' ({{IPAc-en|d|aɪ|ˈ|ɒ|k|s|eɪ|n}}) is a [[Heterocyclic compound|heterocyclic]] [[organic compound]], classified as an [[ether]]. It is a colorless liquid with a faint sweet [[odor]] similar to that of [[diethyl ether]]. The compound is often called simply '''dioxane''' because the other dioxane [[isomer]]s ([[1,2-Dioxane|1,2-]] and [[1,3-Dioxane|1,3-]]) are rarely encountered.

1,4-Dioxane is miscible in water, essentially nonvolatile when dissolved in water, not well adsorbed by activated carbon, and not readily [[Redox|oxidized]] by common oxidants.

Dioxane is used as a solvent in manufacturing applications, and as a stabilizer for the transport of [[chlorinated hydrocarbons]] in aluminium containers.<ref name=wisc>Wisconsin Department of Health Services (2013) [https://www.dhs.wisconsin.gov/publications/p0/p00514.pdf 1,4-Dioxane Fact Sheet] {{Webarchive|url=https://web.archive.org/web/20201016235134/https://www.dhs.wisconsin.gov/publications/p0/p00514.pdf |date=16 October 2020 }}. Publication 00514. Accessed 2016-11-12.</ref> It is a highly [[Combustibility and flammability|flammable]] substance that produces toxic vapors when heated.<ref name=pubchem/>

Although it is a trace material in commonly used products, such as [[cosmetics]], dioxane is considered a hazardous contaminant and potential [[carcinogen]] in many countries, requiring government monitoring of amounts used in manufacturing and its presence in air, drinking water, and [[ecosystem]]s.<ref name="pubchem">{{cite web |title=1,4-Dioxane |url=https://pubchem.ncbi.nlm.nih.gov/compound/31275 |publisher=PubChem, US National Library of Medicine |access-date=16 July 2025 |date=13 July 2025}}</ref><ref name="fda-22">{{cite web |title=1,4-Dioxane in Cosmetics: A Manufacturing Byproduct |url=https://www.fda.gov/cosmetics/potential-contaminants-cosmetics/14-dioxane-cosmetics-manufacturing-byproduct |publisher=US Food and Drug Administration |access-date=16 July 2025 |date=3 March 2022}}</ref><ref name="canada">{{cite web |title=Guidelines for Canadian Drinking Water Quality: Guideline Technical Document - 1,4-Dioxane |url=https://www.canada.ca/en/health-canada/services/publications/healthy-living/guidelines-canadian-drinking-water-quality-guideline-1-4-dioxane.html |publisher=Government of Canada |access-date=16 July 2025 |date=26 March 2021}}</ref>

== History and synthesis == The compound was discovered by Portuguese professor [[Agostinho Vicente Lourenço]] in 1860 by a reaction of [[diethylene glycol]] with [[1,2-dibromoethane]].<ref>{{Cite book |last= |first= |url=https://books.google.com/books?id=5oI5AAAAcAAJ&pg=PA207 |title=Bulletin de la Société Chimique de Paris |date=1860 |publisher=Hachette|location=Paris |pages=207 |language=fr}}</ref> He initially designated it ''ether of glycol'' and correctly identified its [[empirical formula]], but measured its boiling point at about 95&nbsp;°C.<ref>{{Cite thesis |last=Lourenco |first=Agostinho Vicente |url=https://books.google.com/books?id=pKdcAAAAcAAJ&pg=PA37 |title=Thèses présentées à la Faculté des Sciences de Paris pour le Doctorat ès Sciences physiques |date=1862 |location=Paris|publisher=Paris Academy |pages=37–40 |language=fr}}</ref> Three years later [[Charles Adolphe Wurtz|C. A. Wurtz]] obtained it by another method, called it ''dioxyethylene'' and studied some of its chemical properties.<ref>{{Cite book |url=https://books.google.com/books?id=g69JAQAAMAAJ&pg=PA323 |title=Annales de chimie et de physique |last7=Haller |first7=Albin |date=1863 |publisher=Masson. |pages=323–326 |language=fr}}</ref>

Dioxane is industrially produced since the 1920s<ref>{{Cite book |last=Sub-committee |first=Great Britain British Intelligence Objectives |url=https://books.google.com/books?id=N7JQAAAAYAAJ&q=Ludwigshafen+dioxan+1920 |title=B.I.O.S. Final Report |publisher=H.M. Stationery Office |language=en}}</ref><ref>{{Cite book |last=Mohr |first=Thomas K. G. |url=https://books.google.com/books?id=wUnLBQAAQBAJ&pg=PA52 |title=Environmental Investigation and Remediation: 1,4-Dioxane and other Solvent Stabilizers |date=2016-04-19 |publisher=CRC Press |isbn=978-0-203-48937-6 |language=en}}</ref> by the acid-catalysed [[Dehydration reaction|dehydration]] of diethylene glycol, which in turn is obtained from the [[hydrolysis]] of [[ethylene oxide]]. This method was developed by [[Alexey Favorsky]] in 1906, who also determined the structure of the compound.<ref>{{Cite book |last=Быков |first=Георгий Владимирович |url=https://books.google.com/books?id=76RbAAAAIAAJ&q=%D0%B4%D0%B8%D0%BE%D0%BA%D1%81%D0%B0%D0%BD |title=История органической химии: Открытие важнейших органических соединений |date=1978 |publisher=Наука |language=ru}}</ref>

In 1985, the global production capacity for dioxane was between 11,000 and 14,000 tons.<ref name=Ullmann /> In 1990, the total U.S. production volume of dioxane was between 5,250 and 9,150 tons.<ref name=OPPT>{{cite web |url= http://www.epa.gov/chemfact/dioxa-sd.pdf |archive-url= https://web.archive.org/web/20040716155301/http://www.epa.gov/chemfact/dioxa-sd.pdf |url-status= dead |archive-date= 16 July 2004 |publisher= [[United States Environmental Protection Agency]] |work= OPPT Chemical Fact Sheets |date= February 1995 |title= 1, 4-Dioxane Fact Sheet: Support Document |access-date=14 May 2010 <!--Added by DASHBot-->}}</ref>

== Structure == [[File:Dioxane isomers.svg|thumb|upright=1.2|The three isomers of dioxane|left]] Three isomers of dioxane exist, but only the 1,3- and 1,4- isomers are significant. The 1,4-dioxane molecule is conformationally flexible: the centrosymmetric chair and the [[boat conformation]]s easily interconvert such that the H NMR spectrum shows only one signal. For this reason, it is sometimes used as an internal standard for [[nuclear magnetic resonance spectroscopy]] in [[deuterium oxide]].<ref>{{cite journal |last1=Shimizu |first1=A. |last2=Ikeguchi |first2=M. |last3=Sugai |first3=S. |title=Appropriateness of DSS and TSP as internal references for 1H NMR studies of molten globule proteins in aqueous media |journal=[[Journal of Biomolecular NMR]] |volume=4 |year=1994 |doi=10.1007/BF00398414 |pmid=22911388 |issue=6|pages=859–62 |s2cid=34800494 }}</ref> With only two ethyleneoxyl units, dioxane is one of the smallest [[crown ether]]s.

== Uses ==

=== Trichloroethane transport === In the 1980s, most of the dioxane produced was used as a stabilizer for [[1,1,1-Trichloroethane|1,1,1-trichloroethane]] for storage and transport in [[aluminium]] containers. Normally aluminium is protected by a passivating oxide layer, but when these layers are disturbed, the metallic aluminium reacts with trichloroethane to give [[aluminium trichloride]], which in turn catalyses the [[dehydrohalogenation]] of the remaining trichloroethane to [[vinylidene chloride]] and [[hydrogen chloride]].<ref name=pubchem/> Dioxane "poisons" this catalysis reaction by forming an [[adduct]] with aluminium trichloride.<ref name=Ullmann>{{cite book |last1=Surprenant |first1=Kenneth S. |title=Dioxane in Ullmann's Encyclopedia of Industrial Chemistry |year=2000 |doi=10.1002/14356007.a08_545|chapter=Dioxane |isbn=978-3527306732 }}</ref>

=== As a solvent === [[File:Binary phase diagram dioxane-water.svg|left|thumb|200px|Binary [[phase diagram]] for the system 1,4-dioxane/water]] Dioxane is used in a variety of applications as a versatile [[aprotic solvent]] (usually considered non-polar,<ref>{{Cite web |date=2014-05-28 |title=Polar Protic and Aprotic Solvents |url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Fundamentals/Intermolecular_Forces/Polar_Protic_and_Aprotic_Solvents |access-date=2025-02-03 |website=Chemistry LibreTexts |language=en}}</ref> although some sources state otherwise<ref>{{Cite book |last1=Crespo |first1=J. G. |url=https://books.google.com/books?id=KwnoCAAAQBAJ&pg=PA94 |title=Membrane Processes in Separation and Purification |last2=Böddeker |first2=Karl W. |date=2013-11-11 |publisher=Springer Science & Business Media |isbn=978-94-015-8340-4 |language=en}}</ref>), e.g. for inks, adhesives, and cellulose esters.<ref name=pubchem/> It is substituted for [[tetrahydrofuran]] (THF) in some processes, because of its lower toxicity and higher boiling point (101&nbsp;°C, versus 66&nbsp;°C for THF).<ref name=weiss>Klaus Weissermel, Hans-Jürgen Arpe (2003) "Industrial Organic Chemistry". John Wiley & Sons, page 158. {{ISBN|3527305785}}, 9783527305780.</ref>

While diethyl ether is rather insoluble in water, dioxane is [[miscible]] and in fact is [[hygroscopic]]. At standard pressure, the mixture of water and dioxane in the ratio 17.9:82.1 by mass is a positive [[azeotrope]] that boils at 87.6 °C.<ref>{{cite journal | doi = 10.1021/ja01246a015 | title = The Ternary System: Dioxane—Ethanol—Water | date = 1943 | last1 = Schneider | first1 = Charles H. | last2 = Lynch | first2 = Cecil C. | journal = Journal of the American Chemical Society | volume = 65 | issue = 6 | pages = 1063–1066 | bibcode = 1943JAChS..65.1063S }}</ref>

The oxygen atoms are weakly [[Lewis base|Lewis-basic]]. It forms adducts with a variety of Lewis acids. It is classified as a [[HSAB theory|hard base]] and its base parameters in the [[ECW model]] are E<sub>B</sub>&nbsp;=&nbsp;1.86 and C<sub>B</sub>&nbsp;=&nbsp;1.29.

Dioxane produces insoluble [[coordination polymer]]s by linking metal centers.<ref>{{cite journal |doi=10.1002/chem.201903120|title=Structure–Solubility Relationship of 1,4-Dioxane Complexes of Di(hydrocarbyl)magnesium |year=2019 |last1=Fischer |first1=Reinald |last2=Görls |first2=Helmar |last3=Meisinger |first3=Philippe R. |last4=Suxdorf |first4=Regina |last5=Westerhausen |first5=Matthias |journal=Chemistry – A European Journal |volume=25 |issue=55 |pages=12830–12841 |pmid=31328293 |pmc=7027550 |bibcode=2019ChEuJ..2512830F }}</ref> In this way, it is used to drive the [[Schlenk equilibrium]], allowing the synthesis of dialkyl magnesium compounds.<ref name=Ullmann /> [[Dimethylmagnesium]] is prepared in this manner:<ref>{{cite journal |title=The Preparation of Dialkylmagnesium Compounds from Grignard Reagents|last1=Cope |first1=Arthur C. |journal=Journal of the American Chemical Society |volume=57 |page=2238 |year=1935 |doi=10.1021/ja01314a059 |issue=11 |bibcode=1935JAChS..57.2238C }}</ref><ref>{{cite journal |last1=Anteunis |first1=M. |title=Studies of the Grignard Reaction. II. Kinetics of the Reaction of Dimethylmagnesium with Benzophenone and of Methylmagnesium Bromide-Magnesium Bromide with Pinacolone |journal=The Journal of Organic Chemistry |volume=27 |page=596 |year=1962 |doi=10.1021/jo01049a060 |issue=2}}</ref> :2 CH{{sub|3}}MgBr + (C{{sub|2}}H{{sub|4}}O){{sub|2}} → MgBr{{sub|2}}(C{{sub|2}}H{{sub|4}}O){{sub|2}} + (CH{{sub|3}}){{sub|2}}Mg

== Toxicology ==

=== Safety === Dioxane vapor is irritating to the eyes and respiratory tract; its contamination of air, food, drinking water, or cosmetics are examples of typical exposure.<ref name=pubchem/> High levels of 1,4-dioxane in the air can result in injury to the [[nasal cavity]], liver, or kidneys.<ref name="cdc">{{cite web |title=ToxFAQs for 1,4-Dioxane |url=https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=954&toxid=199 |publisher=Agency for Toxic Substances and Disease Registry, US Centers for Disease Control and Prevention |access-date=16 July 2025 |date=18 June 2015}}</ref>

As a flammable compound, dioxane under high heat or fire may produce irritating, corrosive and toxic vapors causing dizziness or [[Asphyxia|asphyxiation]] in confined work spaces.<ref name=pubchem/> Environmental contamination, especially in drinking water, may occur from manufacturing runoff or uncontrolled waste disposal.<ref name=canada/><ref name=cdc/><ref name="epa">{{cite web |title=Final Risk Evaluation for 1,4-Dioxane |url=https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/final-risk-evaluation-14-dioxane |publisher=US Environmental Protection Agency |access-date=16 July 2025 |date=13 November 2024|quote=EPA identified health risks, risks of liver toxicity, adverse effects in the olfactory epithelium, and cancer from inhalation or dermal exposures to 1,4-dioxane, as well as from ingestion of drinking water. Risk from several conditions of use (including manufacturing, import, processing, industrial and commercial uses, and disposal) of 1,4-dioxane, including as a byproduct, significantly contribute to the whole chemical determination of unreasonable risk of injury to health}}</ref>

Dioxane is classified by several government agencies as a potential cancer-causing chemical.<ref name=fda-22/><ref name=canada/><ref name=cdc/><ref name=epa/> It is also classified by the [[International Agency for Research on Cancer|IARC]] as a [[List of IARC Group 2B carcinogens|Group 2B carcinogen]]: ''possibly carcinogenic to humans'' because it is a known carcinogen in other animals.<ref>{{cite book |title= IARC Monographs Volume 71 |publisher= International Agency for Research on Cancer |url= http://monographs.iarc.fr/ENG/Monographs/vol71/mono71-25.pdf|access-date =11 July 2014}}</ref> In 2024, the [[United States Environmental Protection Agency]] classified dioxane as a probable human carcinogen and an unreasonable risk to human health, which establishes a legal basis for federal regulation under the [[Toxic Substances Control Act]].<ref name=epa/><ref name="Bettenhausen 2025">{{cite web |last=Bettenhausen |first=Craig |title=Cleaning out a carcinogenic contaminant |website=Chemical & Engineering News |date=28 January 2025 |url=https://cen.acs.org/business/consumer-products/Cleaning-carcinogenic-contaminant/103/i2 |access-date=20 October 2025}}</ref> The State of New York has adopted a first-in-the-nation drinking water standard for 1,4-dioxane and set the maximum contaminant level of 1 part per billion.<ref>{{Cite web |url=https://www.governor.ny.gov/news/governor-cuomo-announces-first-nation-drinking-water-standard-emerging-contaminant-14-dioxane |title = Governor Cuomo Announces First in the Nation Drinking Water Standard for Emerging Contaminant 1,4-Dioxane {{!}} Governor Andrew M. Cuomo |access-date=30 October 2020 |archive-date=29 October 2020 |archive-url=https://web.archive.org/web/20201029142313/https://www.governor.ny.gov/news/governor-cuomo-announces-first-nation-drinking-water-standard-emerging-contaminant-14-dioxane |url-status=dead }}</ref>

=== Explosion hazard === Like some other ethers, dioxane combines with atmospheric oxygen upon prolonged exposure to air to form potentially explosive [[peroxide]]s.<ref name=pubchem/> [[Distillation]] of these mixtures is dangerous.<ref name=pubchem/> Storage over metallic sodium could limit the risk of peroxide accumulation.<ref>{{cite web |author1=European Chemicals Agency |title=ANNEX 1 in support of the Committee for Risk Assessment (RAC) for evaluation of limit values for 1,4-dioxane at the workplace |url=https://echa.europa.eu/documents/10162/073d44ca-5ad2-8128-fd15-8c74a4bdb126 |website=European Chemicals Agency |access-date=13 March 2025 |ref=ECHA/RAC/OEL-O-0000007101-89-01/F |pages=9 |language=English |date=18 March 2022}}</ref>

=== Environment === Dioxane biodegrades through a number of pathways.<ref>{{cite journal |last1=Zenker |first1=Matthew J. |last2=Borden |first2=Robert C. |last3=Barlaz |first3=Morton A. |title=Occurrence and Treatment of 1,4-Dioxane in Aqueous Environments |journal=Environmental Engineering Science |date=September 2003 |volume=20 |issue=5 |pages=423–432 |doi=10.1089/109287503768335913}}</ref><ref>{{cite journal |last1=Zhang |first1=Shu |last2=Gedalanga |first2=Phillip B. |last3=Mahendra |first3=Shaily |title=Advances in bioremediation of 1,4-dioxane-contaminated waters |journal=Journal of Environmental Management |date=December 2017 |volume=204 |issue=Pt 2 |pages=765–774 |doi=10.1016/j.jenvman.2017.05.033|pmid=28625566 |doi-access=free |bibcode=2017JEnvM.204..765Z }}</ref>

Dioxane has affected groundwater supplies in several areas.<ref name=canada/><ref name=epa/> Dioxane at the level of 1 μg/L (~1 ppb) has been detected in many locations in the US.<ref name="OPPT" /> In the U.S. state of New Hampshire, it was found at 67 sites in 2010, ranging in concentration from 2 ppb to over 11,000 ppb. Thirty of these sites are solid waste landfills, most of which have been closed for years. In 2019, the Southern Environmental Law Center successfully sued Greensboro, North Carolina's Wastewater treatment after 1,4-Dioxane was found at 20 times above EPA safe levels in the Haw River.<ref>{{Cite web |date=2020-11-18 |title=1,4-dioxane in Greensboro {{!}} Haw River Assembly |work=Haw River Assembly {{pipe}} Defending the river since 1982 |url=https://hawriver.org/14-dioxane-in-greensboro/ |access-date=2022-05-13 |language=en-US}}</ref>

=== Consumer products === As a byproduct of the [[ethoxylation]] process, a route to some ingredients found in cleansing and moisturizing products, traces of dioxane can be found in cosmetics and personal care products, such as deodorants, perfumes, shampoos, toothpastes, and mouthwashes.<ref name=fda-22/><ref name=cdc/><ref>{{cite web |title= Chemical Encyclopedia: 1,4-dioxane |publisher= Healthy Child Healthy World |url= http://healthychild.org/issues/chemical-pop/1,4-dioxane/ |access-date =14 December 2009 |archive-url= https://web.archive.org/web/20091129073643/http://healthychild.org/issues/chemical-pop/1,4-dioxane/ |archive-date= 29 November 2009 <!--Added by DASHBot-->}}</ref> The ethoxylation process makes the cleansing agents, such as [[sodium laureth sulfate]] and ammonium laureth sulfate, less abrasive and offers enhanced foaming characteristics. Dioxane is found in small amounts in some cosmetics.<ref name=fda-22/><ref name=canada/>

Since 1979, the U.S. Food and Drug Administration conducted tests on cosmetic raw materials and finished products for the levels of 1,4-dioxane.<ref name=fda-22/><ref name="Occurrence_Dioxane" /><ref name="Mohr 2020">{{cite book |last=Mohr |first=Thomas K.G. |title=Environmental Investigation and Remediation |chapter=1,4-Dioxane Chemistry, Uses, and Occurrence |publisher=CRC Press |year=2020 |isbn=978-0-429-40142-8 |doi=10.1201/9780429401428-2 |url=https://www.taylorfrancis.com/books/9780429685781/chapters/10.1201/9780429401428-2 |access-date=18 October 2025 |page=94–95, 101}}</ref> 1,4-Dioxane was present in ethoxylated raw ingredients at levels up to 1410 ppm (~0.14%wt), and at levels up to 279 ppm (~0.03%wt) in off the shelf cosmetic products.<ref name="Occurrence_Dioxane" /> Levels of 1,4-dioxane exceeding 85 ppm (~0.01%wt) in children's shampoos indicate that close monitoring of raw materials and finished products is warranted.<ref name="Occurrence_Dioxane">{{cite journal |last1=Black |first1=RE |last2=Hurley |first2=FJ |last3=Havery |first3=DC |title=Occurrence of 1,4-dioxane in cosmetic raw materials and finished cosmetic products |journal=Journal of AOAC International |volume=84 |issue=3 |pages=666–70 |year=2001 |doi=10.1093/jaoac/84.3.666 |pmid=11417628|doi-access=free }}</ref> Since the presence of 1,4-dioxane was recognized, many manufacturers have implemented purification processes, such as vacuum and [[steam stripping]], to reduce its concentration in finished products.<ref name="Mohr 2020"/><ref name="Bettenhausen 2020">{{cite web |last=Bettenhausen |first=Craig A. |title=How companies are getting 1,4-dioxane out of home and personal care products |website=Chemical & Engineering News |date=22 March 2020 |url=https://cen.acs.org/business/consumer-products/companies-getting-14-dioxane-home/98/i11 |access-date=19 October 2025}}</ref> While the FDA encourages manufacturers to remove 1,4-dioxane, it is not required by federal law.<ref name=fda-22/><ref name="FDA_Dioxane">FDA/CFSAN--Cosmetics Handbook Part 3: Cosmetic Product-Related Regulatory Requirements and Health Hazard Issues. [https://web.archive.org/web/20080115201046/http://www.cfsan.fda.gov/~dms/cos-hdb3.html Prohibited Ingredients and other Hazardous Substances: 9. Dioxane] Web.archive.org</ref>

On 9 December 2019, the State of New York amended Environmental Conservation Law (ECL) to regulate 1,4-dioxane in consumer products. The law restricts 1,4-dioxane concentrations in household cleansing and personal care products to a maximum of 2 ppm starting 31 December 2022, and a stricter limit of 1 ppm beginning 31 December 2023. Cosmetic products face a maximum allowable concentration of 10 ppm of 1,4-dioxane as of 31 December 2022.<ref>{{cite web|url=https://cen.acs.org/environment/persistent-pollutants/New-York-restricts-14-dioxane/97/web/2019/12|title=New York restricts 1,4-dioxane in cleaning and personal care products|website=Cen.acs.org|access-date=13 November 2021}}</ref><ref name="DEC 2024">{{cite web |title=1,4-Dioxane Limits for Household Cleansing, Personal Care, and Cosmetic Products |website=Department of Environmental Conservation |url=https://dec.ny.gov/environmental-protection/help-for-businesses/household-personal-cosmetic-dioxane-limits |access-date=19 October 2025}}</ref>

== See also == * [[Dioxolane]] * [[9-Crown-3]]

== References == {{Reflist}}

{{Authority control}}

{{DEFAULTSORT:Dioxane, 1,4-}} [[Category:Dioxanes]] [[Category:Ether solvents]] [[Category:IARC Group 2B carcinogens]] [[Category:Crown ethers]] [[Category:Sweet-smelling chemicals]]