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			{{short description|Chemical compound in very wide use}}
			{{use dmy dates |date=September 2022}}
	{{chembox		{{chembox
			| Verifiedfields = changed
	| verifiedrevid = 418144966
			| Watchedfields = changed
	| Name = Tetrachloroethylene
			| verifiedrevid = 433348706
	| ImageFileL1 = Tetrachloroethylene.svg
			| Name = Tetrachloroethylene
	| ImageSizeL1 = 100px
	| ImageNameL1 = Tetrachloroethylene		| ImageFileL1 = Tetrachloroethylene.svg
	| ImageFileR1 = Tetrachloroethylene-3D-vdW.png		| ImageNameL1 = Tetrachloroethylene
			| ImageFileR1 = Tetrachloroethylene-3D-vdW.png
	| ImageSizeR1 = 120px
	| ImageNameR1 = Tetrachloroethylene		| ImageNameR1 = Tetrachloroethylene
			| ImageCaptionR1 = {{legend|black|], C}}{{legend|lime|], Cl}}
	| IUPACName = Tetrachloroethene
			| ImageFile2 = Tetrakloroetilen2.jpg
	| OtherNames = Perchloroethene; Perchloroethylene; Perc; PCE
			| ImageSize2 = 150
	| Section1 = {{Chembox Identifiers
			| PIN = Tetrachloroethene
	| SMILES = Cl/C(Cl)=C(/Cl)Cl
			| OtherNames = Carbon bichloride; Carbon dichloride (''Carboneum Dichloratum''); Ethylene tetrachloride; Perchlor; Perchloroethene; Perchloroethylene;
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
			|Section1={{Chembox Identifiers
			| Abbreviations= PCE; Perc; Per
			| CASNo_Ref = {{cascite|correct|CAS}}
			| CASNo = 127-18-4
			| Beilstein = 1304635
			| ChEBI_Ref = {{ebicite|changed|EBI}}
			| ChEBI = 17300
			| ChEMBL_Ref = {{ebicite|correct|EBI}}
			| ChEMBL = 114062
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 13837281		| ChemSpiderID = 13837281
			| EINECS = 204-825-9
			| Gmelin = 101142
			| KEGG_Ref = {{keggcite|correct|kegg}}
			| KEGG = C06789
			| PubChem = 31373
			| RTECS = KX3850000
	| UNII_Ref = {{fdacite|correct|FDA}}		| UNII_Ref = {{fdacite|correct|FDA}}
	| UNII = TJ904HH8SN		| UNII = TJ904HH8SN
			| UNNumber = 1897
	| InChI = 1/C2Cl4/c3-1(4)2(5)6		| InChI = 1/C2Cl4/c3-1(4)2(5)6
	| InChIKey = CYTYCFOTNPOANT-UHFFFAOYAO		| InChIKey = CYTYCFOTNPOANT-UHFFFAOYAO
	| ChEMBL_Ref = {{ebicite|correct|EBI}}
	| ChEMBL = 114062
	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}		| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChI = 1S/C2Cl4/c3-1(4)2(5)6		| StdInChI = 1S/C2Cl4/c3-1(4)2(5)6
	| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}		| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChIKey = CYTYCFOTNPOANT-UHFFFAOYSA-N		| StdInChIKey = CYTYCFOTNPOANT-UHFFFAOYSA-N
			| SMILES = ClC(Cl)=C(Cl)Cl
	| CASNo_Ref = {{cascite|correct|CAS}}
	| CASNo = 127-18-4
	| EINECS = 204-825-9
	| RTECS = KX3850000
	| UNNumber = 1897
	| KEGG_Ref = {{keggcite|correct|kegg}}
	| KEGG = C06789
	}}
	| Section2 = {{Chembox Properties
	| C=2|Cl=4
	| Appearance = Clear, colorless liquid
	| Density = 1.622 g/cm<sup>3</sup>
	| Solubility = 0.015 g/100 mL (20 °C)
	| MeltingPtC = -19
	| BoilingPtC = 121.1
	| Viscosity = 0.89 ] at 25 °C
	}}		}}
	| Section7 = {{Chembox Hazards		|Section2={{Chembox Properties
			| C=2 | Cl=4
	| NFPA-F = 0 | NFPA-H = 2 | NFPA-R = 0 | NFPA-O =
			| MolarMassUnit = g/mol
	| ExternalMSDS =
			| Appearance = Clear, very refractive, colorless liquid
	| MainHazards = Harmful (Xn),<br />Dangerous for<br /> the environment (N)
			| Odor = Mild, sharp and sweetish<ref name=PGCH/>
	| FlashPt = Not flammable
	| RPhrases = {{R40}} {{R51/53}}		| Density = 1.622{{nbsp}}g/cm<sup>3</sup>
	| SPhrases = {{S23}} {{S36/37}} {{S61}}		| Solubility = 0.15{{nbsp}}g/L (25{{nbsp}}°C)
			| MeltingPtC = -22.0 to -22.7
			| BoilingPtC = 121.1
			| Viscosity = 0.89{{nbsp}}] at 25{{nbsp}}°C
			| VaporPressure = 14{{nbsp}}mmHg (20{{nbsp}}°C)<ref name=PGCH/>
			| MagSus = −81.6·10<sup>−6</sup>{{nbsp}}cm<sup>3</sup>/mol
			| RefractIndex = 1.505
	}}		}}
	| Section8 = {{Chembox Related		|Section7={{Chembox Hazards
			| NFPA-F = 0 | NFPA-H = 2 | NFPA-R = 0 | NFPA-S =
	| Function = Related ]s
			| NFPA_ref = <ref name="pubchem">{{cite web |url= https://pubchem.ncbi.nlm.nih.gov/compound/31373#section=NFPA-Hazard-Classification |title= Compound Summary: Tetrachloroethylene |publisher=], US National Library of Medicine|date=21 September 2024 |access-date= 24 September 2024}}</ref>
	| OtherFunctn = ]<br />]
			| MainHazards = Inhalation of vapours can cause anaesthesia and respiratory irritation. Causes irritation in contact with skin and eyes with no residual injury.
	| OtherCpds = ]<br />]<br />]
			| ExternalSDS =
			| FlashPt = Not flammable
			| GHSPictograms = {{GHS08}}{{GHS09}}
			| GHSSignalWord = Warning
			| HPhrases = {{H-phrases|351|411}}
			| PPhrases = {{P-phrases|201|202|273|281|308+313|391|405|501}}
			| IDLH = Ca <ref name=PGCH>{{PGCH|0599}}</ref>
			| REL = Ca Minimize workplace exposure concentrations.<ref name=PGCH/>
			| PEL = TWA 100{{nbsp}}ppm<br/>C 200{{nbsp}}ppm (for 5 minutes in any 3-hour period), with a maximum peak of 300{{nbsp}}ppm<ref name=PGCH/>
			| LD50 = 3420 mg/kg (oral, rat)<ref></ref><br>2629 mg/kg (oral, rat), >10000 mg/kg (dermal, rat)<ref></ref>
			| LC50 = 4000{{nbsp}}ppm (rat, 4{{nbsp}}hr)<br/>5200{{nbsp}}ppm (mouse, 4{{nbsp}}hr)<br/>4964{{nbsp}}ppm (rat, 8{{nbsp}}hr)<ref>{{IDLH|127184|Tetrachloroethylene}}</ref>
	}}		}}
			|Section8={{Chembox Related
			| OtherFunction_label = analogous ]s
			| OtherFunction = ] <br /> ]<br />]
			| OtherCompounds = ]<br />]<br />]<br />]}}
	}}		}}
	'''Tetrachloroethylene''', also known under its systematic name '''tetrachloroethene''' and many other names, is a ] with the formula Cl<sub>2</sub>C=CCl<sub>2</sub>. It is a colourless liquid widely used for ] of fabrics, hence it is sometimes called "dry-cleaning fluid." It has a sweet odor detectable by most people at a concentration of 1 part per million (1 ppm). Worldwide production was about 1 megatonne in 1985.<ref name=Ullmann>M. Rossberg et al. “Chlorinated Hydrocarbons” in ''Ullmann’s Encyclopedia of Industrial Chemistry'', 2006, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a06 233.pub2}}</ref>		'''Tetrachloroethylene''', also known as '''perchloroethylene'''{{efn|Previously spelt as '''perchlorethylene'''}} or under the systematic name '''tetrachloroethene''', and abbreviations such as '''perc''' (or '''PERC'''), and '''PCE''', is a ] with the formula {{chem2|Cl2C\dCCl2}}. It is a non-flammable, stable, colorless and heavy liquid widely used for ] of fabrics. It also has its uses as an effective automotive ]. It has a mild sweet, sharp odor, detectable by most people at a concentration of 50 ppm.<ref name=browning>{{cite book |first=Ethel |last=Browning |author-link=Ethel Browning (toxicologist) |title=Toxicity of Industrial Organic Solvents |year=1953 |publisher=Chemical Publishing |section-url=https://archive.org/details/cftri.3112toxicityofindust0000ethe/page/182/mode/1up |pages=182–185 |chapter=Perchloroethylene}}</ref>
			Tetrachloroethylene is regarded as a toxic substance, a ], and an ].<ref name=pubchem/><ref name="tox">{{cite web |author=US Agency for Toxic Substances and Disease Registry |title=Toxicological Profile for Tetrachloroethylene |url=https://www.ncbi.nlm.nih.gov/books/NBK591314/ |publisher=US National Library of Medicine |access-date=23 September 2024 |date=June 2019}}</ref> In 2020, the United States ] stated that "tetrachloroethylene exposure may harm the nervous system, liver, kidneys, and reproductive system, and may be harmful to unborn children", and reported that numerous ] agencies regard it as a ].<ref name="epa">{{cite web |title=Public Health Statement for Tetrachloroethylene (PERC) |url=https://wwwn.cdc.gov/TSP/PHS/PHS.aspx?phsid=263&toxid=48 |publisher=US Environmental Protection Agency |access-date=23 September 2024 |date=22 June 2020}}</ref>
	==Production==
	] first synthesized tetrachloroethene in 1821 by thermal decomposition of ].
	:C<sub>2</sub>Cl<sub>6</sub> &rarr; C<sub>2</sub>Cl<sub>4</sub> + Cl<sub>2</sub>
			==History and production==
	Most tetrachloroethene is produced by high temperature chlorinolysis of light hydrocarbons. The method is related to Faraday's discovery since hexachloroethane is generated and thermally decomposes.<ref name=Ullmann/> Side products include ], ], and ].
			French ] ] first synthesized tetrachloroethylene in 1839 by thermal decomposition of ] following ]'s 1820 synthesis of protochloride of carbon (carbon tetrachloride).
			:{{chem2|C2Cl6 → C2Cl4 + Cl2}}
			Faraday was previously falsely credited for the synthesis of tetrachloroethylene, which in reality, was ].{{Primary source inline|date=October 2024}} While trying to make Faraday's "protochloride of carbon", Regnault found that his compound was different from Faraday's. Victor Regnault stated "According to Faraday, the chloride of carbon boiled around {{convert|70|C|F}} to {{convert|77|C|F}} degrees Celsius but mine did not begin to boil until {{convert|120|C|F}}".<ref>V. Regnault (1839) (On the chlorides of carbon CCl and CCl<sup>2</sup>), ''Annales de Chimie et de Physique'', vol. 70, pages 104–107. Reprinted in German as: {{cite journal
			|journal =Annalen der Pharmacie
			|volume = 30
			|issue = 3
			|year = 1839
			|title = Ueber die Chlorverbindungen des Kohlenstoffs, C2Cl2 und CCl2
			|author = V. Regnault
			|doi = 10.1002/jlac.18390300310
			|pages =350–352
			|url = https://zenodo.org/record/1426937
			}}</ref>
			Tetrachloroethylene can be made by passing chloroform vapour through a red-hot tube, the side products include ] and ], as reported in 1886.<ref>] and ], ], 1886, p. 628</ref>
	Several other methods have been developed. When ] is heated to 400 °C with ], tetrachloroethene is produced by the ]:
	:ClCH<sub>2</sub>CH<sub>2</sub>Cl + 3 Cl<sub>2</sub> → Cl<sub>2</sub>C=CCl<sub>2</sub> + 4 ]
	This reaction can be ] by a mixture of ] and ] or by activated ]. ] is a major byproduct, which is separated by ].
			Most tetrachloroethylene is produced by high-temperature chlorinolysis of light hydrocarbons. The method is related to Faraday's method since hexachloroethane is generated and thermally decomposes.<ref name=Ullmann/> Side products include ], ], and ].
	According to an EPA report of 1976, the quantity of Tetrachloroethylene (also known as perchloroethylene or PCE) produced in the United States in just one year 1973, totaled 706 million pounds (320,000 metric tons). Daimond Shamrock, Dow Chemical Compnay, E.I DuPont and Vulcan Materials Company (Chemical Division) were among the top eight producers nationwide. <ref>"Assessment of Hazardous Waste Practices: Organic Chemicals, Pesticides and Explosives Industries" prebpublication issue for EPA Libraries and Solid Waste Management Agencies under contract # 68-01-2919, USEPA 1976 </ref>
			Several other methods have been developed. When ] is heated to 400&nbsp;°C with ], tetrachloroethylene is produced:
			:{{chem2|ClCH2CH2Cl + 3 Cl2 → Cl2C\dCCl2 + 4 HCl}}
			This reaction can be ] by a mixture of ] and ] or by activated ]. ] is a major byproduct, which is separated by ].
			Worldwide production was about {{convert|1|e6MT}} in 1985.<ref name=Ullmann>{{Ullmann |last1=Rossberg |first1=M. |last2=Lendle |first2=W. |last3=Pfleiderer |first3=G. |last4=Tögel |first4=A. |last5=Dreher |first5=E.-L. |last6=Langer |first6=E. |last7=Rassaerts |first7=H. |last8=Kleinschmidt |first8=P. |last9=Strack |first9=H. |last10=Cook |first10=R. |last11=Beck |first11=U. |last12=Lipper |first12=K.-A. |last13=Torkelson |first13=T.R. |last14=Löser |first14=E. |last15=Beutel |first15=K.K. |last16=Mann |first16=T. |title=Chlorinated Hydrocarbons |doi=10.1002/14356007.a06_233.pub2}}</ref>
			Although in very small amounts, tetrachloroethylene occurs naturally in volcanoes along with ].<ref>{{cite journal | doi = 10.1021/np50088a001 | last = Gribble |first = G. W. | title = Naturally occurring organohalogen compounds – A comprehensive survey | journal = Progress in the Chemistry of Organic Natural Products | year = 1996 | volume = 68 | pages = 1–423 | pmid = 8795309 | issue = 10}}</ref>
	==Uses==		==Uses==
	Tetrachloroethylene is an excellent ] for ] materials. Otherwise it is volatile, highly stable, and ]. For these reasons, it is widely used in ]. Usually as a mixture with other chlorocarbons, it is also used to degrease metal parts in the ] and other metalworking industries. It appears in a few consumer products including ]s and spot removers.		Tetrachloroethylene is an excellent nonpolar ] for ] materials. Additionally, it is volatile, highly stable (easily recycled) and ], and has low toxicity. For these reasons, it has been widely used in ] worldwide since the 1930s. The chemist ] (1901–1991) had suggested tetrachloroethylene to be used in dry cleaning as an alternative to highly flammable dry cleaning solvents such as ].<ref name="Amos">{{Cite book |last=Amos |first=J. Lawrence |title=A History of the Dow Chemical Physics Lab : the freedom to be creative |date=1990 |publisher=Marcel Dekker, Inc. |editor-last=Boundy |editor-first=Ray H. |location=New York and Basel |pages=71–79 |chapter=Chlorinated solvents |editor-last2=Amos |editor-first2=J. Lawrence}}</ref>
			It is also used to degrease metal parts in the automotive and other metalworking industries, usually as a mixture with other chlorocarbons. It appears in a few consumer products including ]s, aerosol preparations and spot removers.
	===Historical applications===		===Historical applications===
	Tetrachloroethene was once extensively used as an intermediate in the manufacture of ] and related ]s. In the early 20th century, tetrachloroethene was used for the treatment for ] infestation.<ref>{{cite journal |last=Young |first=M.D. |authorlink= |coauthors=''et al.'' |year=1960 |month= |title=The Comparative Efficacy of Bephenium Hydroxynaphthoate and Tetrachloroethylene against Hookworm and other Parasites of Man |journal=American Journal of Tropical Medicine and Hygiene |volume=9 |issue=5 |pages=488–491 |pmid=13787477 |url= |accessdate= |quote= }}</ref>		Tetrachloroethylene was once extensively used as an intermediate in the manufacture of ] and related ]s.
			In the early 20th century, tetrachloroethene was used for the treatment of ] infestation.<ref>{{cite journal |last1=Young |first1=M.D. |last2=Jeffery |first2=G.M. |last3=Morehouse |first3=W.G. |last4=Freed |first4=J.E. |last5=Johnson |first5=R.S. |year=1960 |title=The Comparative Efficacy of Bephenium Hydroxynaphthoate and Tetrachloroethylene against Hookworm and other Parasites of Man |journal=American Journal of Tropical Medicine and Hygiene |volume=9 |issue=5 |pages=488–491 |doi=10.4269/ajtmh.1960.9.488 |pmid=13787477 |s2cid=19521345}}</ref><ref>{{cite journal |author=<!--Staff writer(s); no by-line.--> | title=Clinical Aspects and Treatment of the More Common Intestinal Parasites of Man (TB-33) | journal=Veterans Administration Technical Bulletin 1946 & 1947 | year=1948 | volume=10 | pages=1–14 | url=https://books.google.com/books?id=uJWxEzwqRiMC }}</ref> In 1925, American veterinarian Maurice Crowther Hall (1881–1938), working on anthelmintics, demonstrated the effectiveness of tetrachloroethylene in the treatment of ] caused by ] infestation in humans and animals. Before Hall tested tetrachloroethylene on himself, in 1921 he discovered the powerful effect of carbon tetrachloride on intestinal parasites and was nominated for the Nobel Prize in Physiology or Medicine, but a few years later he found tetrachloroethylene to be more effective and safer.<ref>{{cite web |title=Maurice C. Hall |series=Special Collections |website=] |url=https://www.nal.usda.gov/exhibits/speccoll/items/show/8197}}</ref>
			Tetrachloroethylene treatment has played a vital role in eradicating hookworms in the United States and abroad.{{cn|date=September 2024}} Hall's innovation was considered a breakthrough in medicine.{{cn|date=September 2024}} It was given orally as a liquid or in capsules along with ] to get rid of the '']'' parasite in humans.<ref>{{cite book |last=Davison |first=Forrest Ramon |title=Synopsis of materia medica, toxicology, and pharmacology for students and practitioners of medicine |year=1940 |section-url=https://archive.org/details/b32804878/page/181/mode/1up |page=181 |section=Tetrachlorethylene}}</ref>
			==Chemical properties and reactions==
			Tetrachloroethylene is a derivative of ] with all hydrogens replaced by ]. 14.49% of the molecular weight of tetrachloroethylene consists of ] and the remaining 85.5% is chlorine. It is the most stable compound among all chlorinated derivatives of ] and ethylene. It is resistant to hydrolysis and less corrosive than other chlorinated solvents.<ref name="Ullmann" /> It does not tend to polymerise like fluorine analogue ], {{chem2|C2F4}}.
			Tetrachloroethylene may react violently with ] or ]s, alkalis (] and ]), ], beryllium, barium and aluminium.<ref>{{cite book |editor1-last=Pohanish |editor1-first=Richard P. |title=Sittig's Handbook of Toxic and Hazardous Chemical Carcinogens |edition=6th |year=2012 |publisher=Elsevier |page=2520 |isbn=978-1-4377-7870-0 |section-url=https://books.google.com/books?id=RYt0Wzb60b4C&pg=PA2520 |section=Tetrachloroethylene}}</ref>
			===Oxidation===
			] of tetrachloroethylene by ] in air produces ] and ]:
			:{{chem2|4 C2Cl4 + 3 O2 -> 2 CCl3COCl + 4 COCl2}}
			This reaction can be halted by using amines and phenols (usually ''N''-methyl] and ''N''-methylmorpholine) as stabilisers. But the reaction can be done intentionally to produce trichloroacetyl chloride.<ref name="Ullmann"/>
			===Chlorination===
			] is formed when tetrachloroethylene reacts with ] at 50–80 °C in the presence of a small amount of ] (0.1%) as a catalyst:<ref>Oshin LA, ''Промышленные хлорорганические продукты'' (''Promyshlennyye khlororganicheskie produkty''). 1978.</ref>
			:{{chem2|C2Cl4 + Cl2 -> C2Cl6}}
			] is produced by the reaction of tetrachloroethylene with chlorine and ] in the presence of ]:<ref>Knunyatsya IL. ''Химическая энциклопедия'' (''Khimicheskaya Entsiklopediya''). 1992. {{ISBN|5-85270-039-8}}</ref>
			:{{chem2|C2Cl4 + 3 HF + Cl2 -> CClF2CCl2F + 3 HCl}}
			===Nitration===
			] can be obtained by ] of tetrachloroethylene with ] (conc. {{chem2|HNO3}} rich in ]) or ]:<ref name=argo>{{cite journal |last1=Argo |first1=W. L. |last2=James |first2=E. M. |last3=Donnelly |first3=J. L. |title=Tetrachlordinitroethane |journal=The Journal of Physical Chemistry |date=November 1919 |volume=23 |issue=8 |pages=578–585 |doi=10.1021/j150197a004|url=https://zenodo.org/record/1843020 }}</ref>
			:{{chem2|Cl2CCCl2 + N2O4 -> NO2Cl2CCCl2NO2}}
			The preparation of this crystalline solid compound from Tetrachloroethylene and nitrogen tetroxide was first described by ] in 1869.<ref name=argo/>
			===Thermal decomposition===
			Tetrachloroethylene begins to thermally decompose at 400 °C, decomposition accelerates around 600 °C, and completely decomposes at 800 °C. Organic decomposition products identified were trichlorobutene, 1,3-dichloro-2-propanone, tetrachlorobutadiene, dichlorocyclopentane, dichloropentene, methyl trichloroacetate, tetrachloroacetone, tetrachloropropene, trichlorocyclopentane, trichloropentene, hexachloroethane, pentachloropropene, hexachloropropene, hexachlorobutadiene.<ref name=yasuhara>{{cite journal |first=Akio |last=Yasuhara |title=Thermal decomposition of tetrachloroethylene |journal=Chemosphere |volume=26 |issue=8 |date=April 1993 |pages=1507–1512 |doi=10.1016/0045-6535(93)90218-T |bibcode=1993Chmsp..26.1507Y |s2cid=94961581}}</ref>
	==Health and safety==		==Health and safety==
			Tetrachloroethylene is considered to be a toxin.<ref name=tox/> It is identified as a ] and ].<ref name=pubchem/> Exposure to tetrachloroethylene, especially over a long term, may harm the nervous system, other ], and increase the risk of getting ].<ref name=epa/> It may also have effects on pregnancy and the ].<ref name=epa/>
	The ] has classified tetrachloroethene as a Group 2A ], which means that it is probably carcinogenic to humans.<ref>IARC monograph. , Vol. 63, p. 159. Last Updated May 20, 1997. Last retrieved June 22, 2007.</ref> Like many ], tetrachloroethene is a ] depressant and can enter the body through respiratory or dermal exposure.<ref>. Hazard Controls: Publication 97-157. National Institute for Occupational Safety and Health.</ref> Tetrachloroethene dissolves fats from the skin, potentially resulting in skin irritation.
			Reports of human injury are uncommon despite its wide usage in dry cleaning and degreasing.<ref>{{Ullmann |first1=E.-L. |last1=Dreher |first2=T. R. |last2=Torkelson |first3=K. K. |last3=Beutel |title=Chlorethanes and Chloroethylenes; In: Ullmann's Encyclopedia of Industrial Chemistry |doi=10.1002/14356007.o06_o01|date=19 November 2014|publisher=Wiley|location=Verlag|isbn=9783527306732}}</ref> Although limited by its low ], tetrachloroethylene has potent anaesthetic effects upon inhalation.<ref name=epa/><ref name=foot1943>{{cite journal |first1=Ellen B. |last1=Foot |first2=Virginia |last2=Apgar |author-link2=Virginia Apgar |first3=Kingsley |last3=Bishop |title=Tetrachlorethylene as an Anesthetic Agent |journal=] |date=May 1943 |volume=4 |issue=3 |pages=283–292 |s2cid=70969652 |doi=10.1097/00000542-194305000-00009 |doi-access=free}}</ref> The risk depends on whether exposure is over minutes or hours, or over years.<ref name=epa/>
	Animal studies and a study of 99 twins by Dr. Samuel Goldman and researchers at the Parkinson's Institute in Sunnyvale, California determined there is a "lot of circumstantial evidence" that exposure to Tetrachloroethlene increases the risk of developing Parkinson's disease ninefold. Larger population studies are planned.<ref></ref>
			Despite the advantages of tetrachloroethylene, cancer research and government environmental agencies have called for its replacement from widespread commercial use.<ref name=epa/> It is described as a possible neurotoxicant, ] and ] and reproductive and developmental toxicant (...) a potential occupational carcinogen.<ref name=tox/><ref name=epa/><ref>{{cite journal |doi=10.3389/fpubh.2021.638082 |doi-access=free |title=Perchloroethylene and Dry Cleaning: It's Time to Move the Industry to Safer Alternatives |year=2021 |last1=Ceballos |first1=Diana M. |last2=Fellows |first2=Katie M. |last3=Evans |first3=Ashley E. |last4=Janulewicz |first4=Patricia A. |last5=Lee |first5=Eun Gyung |last6=Whittaker |first6=Stephen G. |journal=Frontiers in Public Health |volume=9 |page=638082 |pmid=33748070 |pmc=7973082 |s2cid=232116380}}</ref> On the other hand, dry cleaning industry emphasizes minimal risk because modern machinery use closed systems to avoid any vapour escape and to optimize recycling.<ref name=Ullmann/>
			=== Metabolism ===
			Tetrachloroethylene's biological half-life is approximately 3 days.<ref name=bio/> About 98% of the inhaled tetrachloroethylene is exhaled unchanged and only about 1–3% is metabolised to ] which rapidly isomerises into ]. Trichloroacetyl chloride hydrolyses to ].<ref>Toxicological Profile for Tetrachloroethylene: Draft. (1995). U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry.</ref><ref name=bio>{{cite book |title=Biological Monitoring: An Introduction |year=1993 |editor=Shane S. Que Hee |page=470 |chapter=Biological Exposure Indices |isbn=978-0-471-29083-4 |publisher=John Wiley & Sons}}</ref>
			===Neurotoxicity===
			Tetrachloroethylene can harm the nervous system, cause developmental deficits in children, impair vision, and increase the risk of ] diagnoses.<ref name=tox/><ref name="grand">{{cite journal |vauthors=Grandjean P, Landrigan PJ |title=Neurobehavioural effects of developmental toxicity |journal=The Lancet. Neurology |volume=13 |issue=3 |pages=330–8 |date=March 2014 |pmid=24556010 |pmc=4418502 |doi=10.1016/S1474-4422(13)70278-3}}</ref><ref name="aschen">{{cite journal |vauthors=Aschengrau A, Janulewicz PA, White RF, Vieira VM, Gallagher LG, Getz KD, Webster TF, Ozonoff DM|display-authors=3 |title=Long-term Neurotoxic Effects of Early-life Exposure to Tetrachloroethylene-contaminated Drinking Water |journal=Annals of Global Health |volume=82 |issue=1 |pages=169–79 |date=2016 |pmid=27325074 |pmc=4916338 |doi=10.1016/j.aogh.2016.01.013}}</ref>
			=== Carcinogenicity ===
			Tetrachloroethylene has been classified as "]: Probably Carcinogenic" by the ] (IARC) due to sufficient evidence in experimental animals and limited evidence in humans for non-Hodgkin lymphoma, urinary bladder cancers, and cancers of the esophagus and cervix.<ref name=iarc2014>{{Cite web |url=https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Trichloroethylene-Tetrachloroethylene-And-Some-Other-Chlorinated-Agents-2014 |title=Trichloroethylene, Tetrachloroethylene, and Some Other Chlorinated Agents (IARC Monograph, Volume 106, 2014) |website=publications.iarc.fr/ |access-date=23 September 2024}}</ref>{{rp|32}}
			Evidence from cohort and case-controlled epidemiologic studies demonstrates a positive association between cumulative exposures to tetrachloroethylene and the prevalence of ], ], and ] in adults. Some limited evidence of increased prevalence of kidney, lung, liver, and breast cancers with exposure to tetrachloroethylene has been found in epidemiologic research, but data quality limitations have produced variable results across studies.<ref name=iarc2014/>{{rp|326}}<ref name=epatox>{{Cite web |url=https://iris.epa.gov/ChemicalLanding/&substance_nmbr=106 |title=Tetrachloroethylene (Perchloroethylene) (United States Environmental Protection Agency, Integrated Risk Information System Toxicological Review, 2012) |website=iris.epa.gov/ |access-date=23 September 2024}}</ref>{{rp|&sect; 4.2.1.3}}<ref name=atsdr>{{Cite web |url=https://www.atsdr.cdc.gov/toxprofiles/tp18.pdf |title=Toxicological Profile for Tetrachloroethylene (United States Agency for Toxic Substances and Disease Registry, 2019) |website=www.atsdr.cdc.gov/ |access-date=23 September 2024}}</ref>{{rp|237}}
			Several modes of action are hypothesized for the carcinogenicity of tetrachloroethylene in humans, though existing data is insufficient for adequate characterization.<ref name=epatox/>{{rp|&sect; 4.2.4, &sect; 4.3.4}} Markers of oxidative metabolism of tetrachloroethylene and increased prevalence of abnormal hepatic sonographs have been observed in dry-cleaners and laundry workers exposed to tetrachloroethylene,<ref name=brodkin>{{cite journal |last1=Brodkin |first1=CA |last2=Daniell |first2=W |last3=Checkoway |first3=H |last4=Echeverria |first4=D |last5=Johnson |first5=J |last6=Wang |first6=K |last7=Sohaey |first7=R |last8=Green |first8=D |last9=Redlich |first9=C |last10=Gretch |first10=D |title=Hepatic ultrasonic changes in workers exposed to perchloroethylene |journal=] |date=1995 |volume=52 |issue=10 |pages=679–685 |doi=10.1136/oem.52.10.679 |doi-access=free |pmc=1128334 |pmid=7489059}}</ref><ref name=gennari>{{cite journal |last1=Gennari |first1=P |last2=Naldi |first2=M |last3=Motta |first3=R |last4=Nucci |first4=MC |last5=Giacomini |first5=C |last6=Violante |first6=FS |last7=Raffi |first7=GB |title=gamma-Glutamyltransferase isoenzyme pattern in workers exposed to tetrachloroethylene |journal=] |url=https://onlinelibrary.wiley.com/doi/10.1002/ajim.4700210506 |date=1992 |volume=21 |issue=5 |pages=661–671 |doi=10.1002/ajim.4700210506 |pmid=1351699}}</ref> which suggests a potential for hepatocellular damage through the formation of ] from glutathione conjugates during metabolization.<ref name=iarc2014/>{{rp|328}}<ref name=atsdr/>{{rp|10, 189-193}} Although most genotoxicity assays of tetrachloroethylene produced negative findings for genotoxicity and mutagenicity, modest genotoxic effects and mutagenic effects have been identified under certain metabolic activation conditions, and several of tetrachloroethylene's metabolites have been shown to be mutagenic.<ref name=epatox/>{{rp|&sect; 4.10.3}}<ref name=atsdr/>{{rp|172-178}}
	===Testing for exposure===		===Testing for exposure===
	Tetrachloroethene exposure can be evaluated by a breath test, analogous to breath-alcohol measurements. Because it is stored in the body's fat and slowly released into the bloodstream, tetrachloroethene can be detected in the breath for weeks following a heavy exposure. Tetrachloroethylene and ] (TCA), a breakdown product of tetrachloroethene, can be detected in the ].		Tetrachloroethylene exposure can be evaluated by a breath test, analogous to breath-alcohol measurements. Also, for acute exposures, tetrachloroethylene in expired air can be measured.<ref>{{Cite web |date=2021-02-09 |title=Tetrachloroethylene Toxicity: Section 3.1. Evaluation and Diagnosis |url=https://www.atsdr.cdc.gov/csem/tetrachloroethylene/section_3_1.html |access-date=2023-03-02 |website=] |language=en-us}}</ref> Tetrachloroethylene can be detected in the breath for weeks following a heavy exposure. Tetrachloroethylene and its metabolite ], can be detected in the blood.
	In Europe, the Scientific Committee on Occupational Exposure Limits (]) recommends for tetrachloroethylene an ] (8h time-weighted average) of 20 ppm and a short-term exposure limit (15 min) of 40 ppm.<ref>{{cite web|url= http://ec.europa.eu/social/keyDocuments.jsp?type=0&policyArea=82&subCategory=153&country=0&year=0&advSearchKey=recommendation&mode=advancedSubmit&langId=en|title=SCOEL recommendations|date=2011-04-22|accessdate=2011-04-22}}</ref>		In the European Union, the ] (SCOEL) recommends for tetrachloroethylene an ] (8-hour time-weighted average) of 20 ppm and a short-term exposure limit (15 min) of 40 ppm.<ref>{{cite web|url= http://ec.europa.eu/social/keyDocuments.jsp?type=0&policyArea=82&subCategory=153&country=0&year=0&advSearchKey=recommendation&mode=advancedSubmit&langId=en|title=SCOEL recommendations|date=2011-04-22|access-date=2011-04-22}}</ref>
			==Remediation and degradation==
	== Environmental contamination ==
			In principle, tetrachloroethylene contamination can be remediated by chemical treatment. Chemical treatment involves reducing metals such as iron powder.<ref>{{cite journal |first1=Timothy J. |last1=Campbell |first2=David R. |last2=Burris |first3=A. Lynn |last3=Roberts |first4=J. Raymond |last4=Wells |title=Trichloroethylene and tetrachloroethylene reduction in a metallic iron–water-vapor batch system |date=October 2009 |journal=Environmental Toxicology and Chemistry |volume=16 |issue=4 |doi=10.1002/etc.5620160404 |pages=625–630 |s2cid=94525849}}</ref>
	Tetrachloroethene is a common ]. With a specific gravity greater than 1, tetrachloroethylene will be present as a ] if sufficient quantities of liquid are spilled in the environment. Because of its mobility in groundwater, its ] at low levels, and its density (which causes it to sink below the ]), cleanup activities are more difficult than for oil spills. Recent research has focused on the in place ] of soil and ground water pollution by tetrachloroethylene. Instead of excavation or extraction for above-ground treatment or disposal, tetrachloroethylene contamination has been successfully remediated by chemical treatment or bioremediation. Bioremediation has been successful under anaerobic conditions by reductive dechlorination by ''Dehalococcoides'' sp. and under aerobic conditions by cometabolism by ''Pseudomonas'' sp.<ref>{{cite journal | doi = 10.1007/s002530100675 | author = Ryoo, D., Shim, H., Arenghi, F. L. G., Barbieri, P., Wood T. K. | year = 2001 | title = Tetrachloroethylene, Trichloroethylene, and Chlorinated Phenols Induce Toluene-o-xylene Monooxoygenase Activity in Pseudomonas Stutzeri OX1 | journal = Applied Microbiol Biotechnol | volume = 56 | pages = 545–549}}</ref><ref>{{cite journal | doi = 10.1007/BF01020855 | author = Deckard, L. A., Wills, J. C., Rivers, D. B. | year = 1994 | title = Evidence for aerobic degradation of tetrachloroethylene by bacterial isolate | journal = Biotechnol. Lett. | volume = 16 | pages = 1221–1224}}</ref> Partial degradation daughter products include ], cis-] and ]; full degradation converts tetrachloroethylene to ethene and chloride dissolved in water.		] usually entails reductive dechlorination under anaerobic conditions by '']'' spp.<ref>{{cite journal |doi=10.1016/j.watres.2017.02.001 |title=Anaerobic biodegradation of (Emerging) organic contaminants in the aquatic environment |year=2017 |last1=Ghattas |first1=Ann-Kathrin |last2=Fischer |first2=Ferdinand |last3=Wick |first3=Arne |last4=Ternes |first4=Thomas A. |journal=Water Research |volume=116 |pages=268–295 |pmid=28347952 |doi-access=free |bibcode=2017WatRe.116..268G |s2cid=205698959}}</ref> Under aerobic conditions, degradation may occur via co-metabolism by '']'' sp.<ref>{{cite journal |doi=10.1007/s002530100675 |last1=Ryoo |first1=D. |last2=Shim |first2=H. |last3=Arenghi |first3=F. L. G. |last4=Barbieri |first4=P. |last5=Wood |first5=T. K. |year=2001 |title=Tetrachloroethylene, Trichloroethylene, and Chlorinated Phenols Induce Toluene-o-xylene Monooxoygenase Activity in Pseudomonas stutzeri OX1 |journal = Appl Microbiol Biotechnol |volume=56 |pages=545–549 |issue = 3–4 |pmid = 11549035 | s2cid = 23770815 }}</ref> Products of biological reductive dechlorination include ], ''cis''-], ], ethylene and chloride.
			== Explanatory notes ==
	It has been estimated that about 85% of tetrachloroethylene is released into the ]; ] models assumed 90% release into the air and 10% to water. Based on these models, its distribution in the environment is estimated to be in the air (76.39% - 99.69%), water (0.23% - 23.2%), soil (0.06-7%), with the remainder in the sediment and biota. Estimates of lifetime in the atmosphere vary, but a 1987 survey estimated the lifetime in the air has been estimated at about 2 months in the Southern Hemisphere and 5–6 months in the Northern Hemisphere. Degradation products observed in a laboratory include phosgene, trichloroacetyl chloride, hydrogen chloride, carbon dioxide, and carbon monoxide. In water, tetrachloroethylene is degraded very slowly by ], and it is persistent under ] conditions. It is degraded through reductive dechlorination under anaerobic conditions, with the degradation products including trichloroethene, dichloroethene, vinyl chloride, ethene, and ethane.<ref>Watts P. (2006). , ]</ref>
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	==References==		==References==
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	==Further reading==		==Further reading==
	* {{cite web | publisher = ] | year = 1997 | title = Toxicological Profile for Tetrachloroethene | url = http://www.atsdr.cdc.gov/toxprofiles/tp18.html}}		*{{cite web | publisher = ] | year = 1997 | title = Toxicological Profile for Tetrachloroethene | url = https://wwwn.cdc.gov/TSP/ToxProfiles/ToxProfiles.aspx?id=265&tid=48}}
			*{{cite journal | author = Doherty, R.E. | year = 2000 | title = A History of the Production and Use of Carbon Tetrachloride, Tetrachloroethylene, Trichloroethylene and 1,1,1-Trichloroethane in the United States: Part 1 - Historical Background; Carbon Tetrachloride and Tetrachloroethylene | journal = Environmental Forensics | volume = 1 | pages = 69–81 | doi = 10.1006/enfo.2000.0010 | issue = 2 | bibcode = 2000EnvFo...1...69D | s2cid = 97680726 }}
	* {{cite journal | author = Doherty, R.E. | year = 2000 | title = A History of the Production and Use of Carbon Tetrachloride, Tetrachloroethylene, Trichloroethylene and 1,1,1-Trichloroethane in the United States: Part 1 - Historical Background; Carbon Tetrachloride and Tetrachloroethylene | journal = ] | volume = 1 | pages = 69–81 | doi = 10.1006/enfo.2000.0010 }}
	==External links==		==External links==
	* U.S. ]		* U.S. ]
			* U.S. ]
	* Australian page
			*Australian page
	* , by Julian Kesner, New York ''Daily News'', April 20, 2007.
			*, ]
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