View source for Triclosan

{{Short description|Antimicrobial agent}}
{{cs1 config|name-list-style=vanc}}
{{Distinguish|triclocarban}}
{{Chembox
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| verifiedrevid  = 470613750
| ImageFile      = Triclosan.svg
| ImageClass     = skin-invert
| ImageFileL1    = Triclosan ball-and-stick model from xtal 2009.png
| ImageFileR1    = Triclosan spacefill model from xtal 2009.png
| PIN            = 5-Chloro-2-(2,4-dichlorophenoxy)phenol
| OtherNames     = 2,4,4′-Trichloro-2′-hydroxydiphenyl ether<br />5-Chloro-(2,4-dichlorophenoxy)phenol<br />Trichloro-2′-hydroxydiphenyl ether<br />CH-3565<br />Lexol 300<br />Irgasan DP 300<br />Ster-Zac
| Section1       = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 5363
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 4NM5039Y5X
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = D06226
| InChI = 1/C12H7Cl3O2/c13-7-1-3-11(9(15)5-7)17-12-4-2-8(14)6-10(12)16/h1-6,16H
| InChIKey = XEFQLINVKFYRCS-UHFFFAOYAS
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 849
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C12H7Cl3O2/c13-7-1-3-11(9(15)5-7)17-12-4-2-8(14)6-10(12)16/h1-6,16H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = XEFQLINVKFYRCS-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 3380-34-5
| PubChem = 5564
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 164200
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB08604
| SMILES = Clc2cc(Cl)ccc2Oc1ccc(Cl)cc1O
}}
| Section2       = {{Chembox Properties
| C=12 | H=7 | Cl=3 | O=2
| Appearance=White solid
| Density=1.49 g/cm<sup>3</sup>
| MeltingPtC=55-57
| BoilingPtC=120
| Solubility=
}}
| Section6       = {{Chembox Pharmacology
| ATCCode_prefix = D08
| ATCCode_suffix = AE04
| ATC_Supplemental = {{ATC|D09|AA06}} (medicated dressing)
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| Section7       = {{Chembox Hazards
| ExternalSDS = [http://www.glenmartinlimited.com/MSDS/gmmsds1154.pdf MSDS]
| MainHazards=
| FlashPtC = 162.2
| AutoignitionPtC =
| NFPA-H = 2
| NFPA-F = 1
| NFPA-R = 0
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}}

'''Triclosan''' (sometimes abbreviated as '''TCS''') is an [[antibiotic|antibacterial]] and [[fungus|antifungal]] agent present in some consumer products, including [[toothpaste]], [[soap]]s, [[detergent]]s, toys, and surgical cleaning treatments. It is similar in its uses and [[mechanism of action]] to [[triclocarban]]. Its efficacy as an [[antimicrobial agent]], the risk of [[antimicrobial resistance]], and its possible role in [[endocrine disruptor|disrupted hormonal development]] remains controversial.  Additional research seeks to understand its potential effects on organisms and environmental health.

Triclosan was developed in 1966.<ref name=Boy2002>{{cite journal|last1=Boyce|first1=JM|last2=Pittet|first2=D|author3=((Healthcare Infection Control Practices Advisory Committee))|author4=((HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force))|title=Guideline for Hand Hygiene in Health-Care Settings. Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. Society for Healthcare Epidemiology of America/Association for Professionals in Infection Control/Infectious Diseases Society of America|journal=MMWR. Recommendations and Reports|date=25 October 2002|volume=51|issue=RR-16|pages=1–45, quiz CE1–4|pmid=12418624}}</ref> A 2006 study recommended showering with 2% triclosan as a regimen in surgical units [[Decolonization (medicine)|to rid]] patients' skin of [[methicillin-resistant Staphylococcus aureus|methicillin-resistant ''Staphylococcus aureus'']] (MRSA).<ref name="pmid16581155">{{cite journal|last1=Coia|first1=J.E.|last2=Duckworth|first2=G.J.|last3=Edwards|first3=D.I.|last4=Farrington|first4=M.|last5=Fry|first5=C.|last6=Humphreys|first6=H.|last7=Mallaghan|first7=C.|last8=Tucker|first8=D.R.|author9=Joint Working Party of the British Society of Antimicrobial Chemotherapy|last10=Hospital Infection|first10=Society|author11=Infection Control Nurses Association|year=2006|title=Guidelines for the control and prevention of meticillin-resistant ''Staphylococcus aureus'' (MRSA) in healthcare facilities|journal=Journal of Hospital Infection|volume=63|pages=S1–44|doi=10.1016/j.jhin.2006.01.001|pmid=16581155}}</ref> 
== Uses ==
Triclosan was used as a hospital scrub in the 1970s. Prior to its change in regulatory status in the EU and US, it had expanded commercially and was a common ingredient in soaps (0.10–1.00%), [[shampoo]]s, [[deodorant]]s, [[toothpaste]]s, [[mouthwash]]es, cleaning supplies, and [[pesticide]]s.<ref name=pmid15765937>{{cite journal |doi=10.2175/106143005X41636 |pmid=15765937 |jstor=25045839 |title=The Fate and Removal of Triclosan during Wastewater Treatment |journal=Water Environment Research |volume=77 |issue=1 |pages=63–67 |year=2005 |last1=Thompson |first1=A. |last2=Griffin |first2=P. |last3=Stuetz |first3=R. |last4=Cartmell |first4=E.|bibcode=2005WaEnR..77...63T |s2cid=33816435 |doi-access=free |hdl=1959.4/41201 |hdl-access=free }}</ref> It also was part of consumer products, including kitchen utensils, toys, bedding, socks, and trash bags.<ref name=pmid15765937/><ref>{{CPID|id=95}}</ref>

Triclosan was registered as a pesticide in 1969.<ref name=":0" /> U.S. EPA registration numbers are required for all EPA-registered pesticides.<ref>{{Cite web |last=US EPA |first=OCSPP |date=2013-02-27 |title=About Pesticide Registration |url=https://www.epa.gov/pesticide-registration/about-pesticide-registration |access-date=2024-01-17 |website=[[United States Environmental Protection Agency]] |language=en}}</ref> As of 2017, there were five registrations for triclosan with the EPA.<ref>National Pesticide Information Retrieval System. Retrieved from http://ppis.ceris.purdue.edu/ {{Webarchive|url=https://web.archive.org/web/20171004114524/http://ppis.ceris.purdue.edu/ |date=2017-10-04 }}, http://ppis.ceris.purdue.edu/chemical2.aspx </ref> Currently, there are 20 antimicrobial registrations with the EPA under the regulations of the [[Federal Insecticide, Fungicide, and Rodenticide Act|Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)]].<ref name=":0" /> The antimicrobial active ingredient is added to a variety of products where it acts to slow or stop the growth of bacteria, fungi, and mildew.  In commercial, institutional, and industrial equipment uses, triclosan is incorporated in conveyor belts, fire hoses, dye bath vats, or ice-making equipment as an antimicrobial. Triclosan may be directly applied to commercial [[HVAC]] coils, where it prevents microbial growth that contributes to product degradation.<ref name=":0">{{Cite web |title=Triclosan Facts {{!}} Pesticides {{!}} US EPA |url=https://archive.epa.gov/pesticides/reregistration/web/html/triclosan_fs.html |access-date=2023-05-26 |website=archive.epa.gov}}</ref>

In the United States, by 2000, triclosan and [[triclocarban]] (TCC) could be found in 75% of liquid soaps and 29% of bar soaps,<ref>{{cite journal |last1=Weatherly |first1=Lisa M. |last2=Gosse |first2=Julie A. |title=Triclosan Exposure, Transformation, and Human Health Effects |journal=Journal of Toxicology and Environmental Health Part B: Critical Reviews |date=2017 |volume=20 |issue=8 |pages=447–469 |doi=10.1080/10937404.2017.1399306 |pmid=29182464 |pmc=6126357 |bibcode=2017JTEHB..20..447W }}</ref> and {{as of|2014|lc=y}} triclosan was used in more than 2,000 consumer products.<ref name=halden/>

In healthcare, triclosan is used in surgical scrubs and hand washes.<ref name=FDA1994>{{cite web |title=Federal Register Notice: Tentative Final Monograph for OTC Healthcare Antiseptic Drug Products |url=https://www.fda.gov/ohrms/dockets/ac/05/briefing/2005-4098B1_02_03-FDA-TAB1.pdf |archive-url=https://web.archive.org/web/20100310204135/http://www.fda.gov/ohrms/dockets/ac/05/briefing/2005-4098B1_02_03-FDA-TAB1.pdf |archive-date=March 10, 2010 |author=Food and Drug Administration |website=[[Food and Drug Administration]] |date=17 June 1994}}</ref> Use in surgical units is effective with a minimum contact time of approximately two minutes.<ref name="pmid2255283"/><ref name="pmid7677266"/> More recently, showering with 2% triclosan has become a recommended regimen in surgical units for the [[Decolonization (medicine)|decolonization]] of patients whose skin carries [[methicillin-resistant Staphylococcus aureus|methicillin-resistant ''Staphylococcus aureus'']] (MRSA).<ref name="pmid16581155"/> Two small uncontrolled case studies reported the use of triclosan correlated with reduction in MRSA infections.<ref name="pmid2255283">{{cite journal |pmid=2255283 |year=1990 |last1=Brady |first1=L.M. |title=Successful control of endemic MRSA in a cardiothoracic surgical unit |journal=The Medical Journal of Australia |volume=152 |issue=5 |pages=240–45 |last2=Thomson |first2=M |last3=Palmer |first3=M.A. |last4=Harkness |first4=J. L.|doi=10.5694/j.1326-5377.1990.tb120917.x |s2cid=20332234 }}</ref><ref name="pmid7677266">{{cite journal |doi=10.1016/0196-6553(95)90042-X |pmid=7677266 |title=Use of 0.3% triclosan (Bacti-Stat) to eradicate an outbreak of methicillin-resistant Staphylococcus aureus in a neonatal nursery |journal=American Journal of Infection Control |volume=23 |issue=3 |pages=200–08 |year=1995 |last1=Zafar |first1=A.B. |last2=Butler |first2=R.C. |last3=Reese |first3=D.J. |last4=Gaydos |first4=L.A. |last5=Mennonna |first5=P.A.}}</ref>

Triclosan is also used in the coatings for some [[surgical sutures]].<ref>{{cite book |last1=Tobias|first1=Karen M.|last2=Johnston|first2=Spencer A.|title=Veterinary Surgery: Small Animal: 2-Volume Set|publisher=Elsevier Health Sciences|isbn=978-0-323-26337-5|page=190|url=https://books.google.com/books?id=p9tyAgAAQBAJ&pg=PA190|access-date=26 January 2016|quote=Triclosan is a commonly used antibiotic coating|date=2013-12-26}}</ref><ref>{{cite book |last1=Singer|first1=Adam J.|last2=Hollander|first2=Judd E.|last3=Blumm|first3=Robert M.|title=Skin and Soft Tissue Injuries and Infections: A Practical Evidence Based Guide|publisher=PMPH-USA|isbn=978-1-60795-029-5|page=95|url=https://books.google.com/books?id=sDLiLLhCDS4C&pg=PA95|access-date=26 January 2016|quote=Examples of antibacterial sutures that are coated with the antibacterial agent triclosan include... In many institutions these have replaced the comparable non-antibacterial sutures.|year=2010}}</ref>  There is good evidence these triclosan-coated sutures reduce the risk of surgical site infection.<ref name="ReferenceA">{{cite journal|last1=Wang|first1=Z.X.|last2=Jiang|first2=C.P.|last3=Cao|first3=Y.|last4=Ding|first4=Y.T.|title=Systematic review and meta-analysis of triclosan-coated sutures for the prevention of surgical-site infection|journal=British Journal of Surgery|date=March 2013|volume=100|issue=4|pages=465–73|doi=10.1002/bjs.9062|pmid=23338685|s2cid=311834}}</ref><ref name="ReferenceB">{{cite journal|last1=Renko|first1=M|last2=Paalanne|first2=N|last3=Tapiainen|first3=T|last4=Hinkkainen|first4=M|last5=Pokka|first5=T|last6=Kinnula|first6=S|last7=Sinikumpu|first7=JJ|last8=Uhari|first8=M|last9=Serlo|first9=W|title=Triclosan-containing sutures versus ordinary sutures for reducing surgical site infections in children: a double-blind, randomised controlled trial|journal=The Lancet. Infectious Diseases|date=January 2017|volume=17|issue=1|pages=50–57|doi=10.1016/S1473-3099(16)30373-5|pmid=27658562}}</ref> The World Health Organization, the American College of Surgeons and the Surgical Infection Society point out the benefit of triclosan-coated sutures in reducing the risk for surgical site infection.<ref name="Ethicon">{{cite web|title=The Centers for Disease Control and Prevention updated guideline now include a recommendation for Triclosan-Coated Sutures {{!}} Ethicon|url=https://www.ethicon.com/na/about-us/news-events/centers-disease-control-and-prevention-updated-guideline-now-include|website=www.ethicon.com|publisher=Ethicon|access-date=2018-05-04|archive-date=2019-08-15|archive-url=https://web.archive.org/web/20190815014332/https://www.ethicon.com/na/about-us/news-events/centers-disease-control-and-prevention-updated-guideline-now-include}}</ref><ref>{{cite journal|last1=Berríos-Torres|first1=Sandra I.|last2=Umscheid|first2=Craig A.|last3=Bratzler|first3=Dale W.|last4=Leas|first4=Brian|last5=Stone|first5=Erin C.|last6=Kelz|first6=Rachel R.|last7=Reinke|first7=Caroline E.|last8=Morgan|first8=Sherry|last9=Solomkin|first9=Joseph S.|last10=Mazuski|first10=John E.|last11=Dellinger|first11=E. Patchen|last12=Itani|first12=Kamal M. F.|last13=Berbari|first13=Elie F.|last14=Segreti|first14=John|last15=Parvizi|first15=Javad|last16=Blanchard|first16=Joan|last17=Allen|first17=George|last18=Kluytmans|first18=Jan A.J.W.|last19=Donlan|first19=Rodney|last20=Schecter|first20=William P.|title=Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection, 2017|journal=JAMA Surgery|date=1 August 2017|volume=152|issue=8|pages=784–91|doi=10.1001/jamasurg.2017.0904|pmid=28467526|doi-access=free}}</ref>

Triclosan has been employed as a [[selectable marker|selective agent]] in molecular cloning. A bacterial host [[transformation (genetics)|transformed]] by a [[plasmid]] harboring a triclosan-resistant mutant ''FabI'' gene (mFabI) as a selectable marker can grow in presence of high dose of triclosan in growth media.<ref>{{cite journal |doi=10.1371/journal.pone.0057075 |pmid=23437314 |pmc=3577784 |title=A Novel Selection Marker for Efficient DNA Cloning and Recombineering in E. Coli |journal=PLOS ONE |volume=8 |issue=2 |article-number=e57075 |year=2013 |last1=Jang |first1=Chuan-Wei |last2=Magnuson |first2=Terry |bibcode=2013PLoSO...857075J|doi-access=free }}</ref>

===Effectiveness===
In surgery, triclosan coated sutures reduce the risk of surgical site infection.<ref name="ReferenceA"/><ref name="ReferenceB"/> Some studies suggest that antimicrobial hand soaps containing triclosan provide a slightly greater bacterial reduction on the hands compared to plain soap.<ref name="Montville">{{cite journal |doi=10.4315/0362-028X.JFP-11-122 |pmid=22054188 |title=A Meta-Analysis of the Published Literature on the Effectiveness of Antimicrobial Soaps |journal=Journal of Food Protection |volume=74 |issue=11 |pages=1875–82 |year=2011 |last1=Montville |first1=Rebecca |last2=Schaffner |first2=Donald W.|doi-access=free }}</ref> {{As of|2013}}, the US [[FDA]] had found clear benefit to health for some consumer products containing triclosan, but not in others; for example the FDA had no evidence that triclosan in antibacterial soaps and body washes provides any benefit over washing with regular soap and water.<ref name="fda">{{cite web |url=https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm205999.htm |archive-url=https://web.archive.org/web/20100411202211/http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm205999.htm |archive-date=April 11, 2010 |title=Triclosan: What Consumers Should Know |publisher=FDA |date=2013-12-16 |access-date=2014-07-15}}</ref>

A [[Cochrane review]] of 30 studies concluded that triclosan/copolymer-containing toothpastes produced a 22% reduction in both [[dental plaque]] and [[gingivitis|gingival inflammation]] when compared with fluoride toothpastes without triclosan/copolymer.<ref name=":1">{{cite journal |doi=10.1002/14651858.CD010514.pub2 |title=Triclosan/copolymer containing toothpastes for oral health |journal=Reviews | pmid=24310847 |pmc=6775959 |volume=12 |issue=12 |year=2013 |article-number=CD010514 | last1 = Riley | first1 = P | last2 = Lamont | first2 = T}}</ref> There was weak evidence of a reduction in [[dental caries|tooth cavities]], and no evidence of reduction in [[periodontitis]].<ref name=":1" />

A study of triclosan toothpastes did not find any evidence that it causes an increase in serious adverse cardiac events such as heart attacks.<ref>{{cite journal |last1=Cullinan |first1=Mary P. |last2=Palmer |first2=Janet E. |last3=Carle |first3=Anne D. |last4=West |first4=Malcolm J. |last5=Westerman |first5=Bill |last6=Seymour |first6=Gregory J. |title=The influence of a triclosan toothpaste on adverse events in patients with cardiovascular disease over 5-years |journal=Science of the Total Environment |date=March 2015 |volume=508 |pages=546–552 |doi=10.1016/j.scitotenv.2014.11.052 |pmid=25442641 |bibcode=2015ScTEn.508..546C |doi-access=free }}</ref>

A study by [[Colgate-Palmolive]] found a significant reduction in gingivitis, bleeding, and plaque with the use of triclosan-containing toothpaste.<ref>{{cite journal |last1=Rover |first1=JA |last2=Leu-Wai-See |first2=P |title=Role of Colgate Total toothpaste in helping control plaque and gingivitis. |journal=American Journal of Dentistry |date=June 2014 |volume=27 |issue=3 |pages=167–70 |pmid=25208366 }}</ref> An independent review by the Cochrane group suggests that the reduction in gingivitis, bleeding, and plaque is [[Statistical significance|statistically significant]] (unlikely to occur by chance) but not [[clinically significant]] (unlikely to provide noticeable effects).<ref>{{cite journal |last1=Kraglund |first1=Ferne |title=Triclosan produces statistically significant reduction in plaque, gingivitis and caries but not clinically important benefit: Question: Are triclosan/copolymer containing fluoride toothpastes more effective than fluoride toothpastes for control of caries, plaque and gingivitis in children and adults? |journal=Evidence-Based Dentistry |date=March 2014 |volume=15 |issue=1 |pages=6–7 |doi=10.1038/sj.ebd.6400980 |pmid=24763165 |s2cid=34379017 |doi-access=free }}</ref>

Triclosan is used in [[food storage]] containers<ref name="Velazquez-2016">{{cite book | editor-last=Barros-Velazquez | editor-first=Jorge | title=Antimicrobial Food Packaging | publication-place=[[Amsterdam]] | date=2016 | doi=10.1016/B978-0-12-800723-5.00033-4 | isbn=978-0-12-800810-2 | oclc=933559725 | s2cid=139202295}}</ref>{{rp|pages=417–423}}<ref name="Chen-et-al-2018">{{cite journal | last1=Chen | first1=Xi | last2=Chen | first2=Mo | last3=Xu | first3=Chenyi | last4=Yam | first4=Kit L. | title=Critical review of controlled release packaging to improve food safety and quality | journal=[[Critical Reviews in Food Science and Nutrition]] | publisher=[[Taylor & Francis]] | volume=59 | issue=15 | date=2018-04-24 | issn=1040-8398 | doi=10.1080/10408398.2018.1453778 | pages=2386–2399 | s2cid=4060996 | pmid=29553807}}</ref> although this use is banned in the [[European Union]] since 2010.<ref name="Chen-et-al-2018" />

[[Veterinary]] use as a biocidal product in the EU is governed by the [[Biocidal Products Directive]].<ref name="europeancommission">{{cite web | title=2. What are the main uses of triclosan? | website=[[European Commission]] | date=2009-06-12 | url=http://ec.europa.eu/health/scientific_committees/opinions_layman/triclosan/en/l-3/2-uses-cosmetics-disinfectant.htm | access-date=2022-07-06}}</ref>

== Chemical structure and properties ==
This [[organic compound]] is a white powdered [[solid]] with a slight aromatic, phenolic odor. Categorized as a [[polychloro phenoxy phenol]], triclosan is a [[chlorine|chlorinated]] [[simple aromatic ring|aromatic compound]] that has [[functional group]]s representative of both [[ether]]s and [[phenol]]s. Phenols often demonstrate antibacterial properties. Triclosan is soluble in [[ethanol]], [[methanol]], [[diethyl ether]], and strongly [[base (chemistry)|basic]] [[Solution (chemistry)|solution]]s such as a 1[[concentration#Molarity|M]] [[sodium hydroxide]] solution, but only slightly soluble in water.<ref>{{Cite web|url=http://copublications.greenfacts.org/en/triclosan/figtableboxes/table-3.htm|title=Table 3: Solubility of triclosan in selected solvents and chemicals - Figures and Tables|website=copublications.greenfacts.org|access-date=2018-12-19}}</ref> Triclosan can be synthesized from [[2,4-dichlorophenol]].

===Synthesis===
Under a reflux process, 2,4,4'-trichloro-2'-methoxydiphenyl ether is treated with [[aluminium chloride]].<ref>Commonwealth of Australia. Department of Health and Ageing. [http://oehha.ca.gov/prop65/public_meetings/052909coms/triclosan/ciba1.pdf National Industrial Chemicals Notification and Assessment Scheme. Priority Existing Chemical Assessment Report No. 30] {{Webarchive|url=https://web.archive.org/web/20101114131316/http://www.oehha.ca.gov/prop65/public_meetings/052909coms/triclosan/ciba1.pdf |date=2010-11-14 }}. National Industrial Chemicals Notification and Assessment Scheme, Jan. 2009. Web. Apr. 2014.</ref>

The United States Pharmacopeia formulary has published a monograph for triclosan that sets purity standards.<ref name=USP>{{cite book |title=US Pharmacopoeia National Formulary|year=2012|publisher=United States Pharmacopeial|isbn=978-1-936424-12-2|url=http://www.usp.org/}}</ref>

==Mechanism of action==
At high concentrations, triclosan acts as a [[biocide]] with multiple [[cytoplasm]]ic and [[cell membrane|membrane]] targets.<ref name="pmid15073159">{{cite journal |author=Russell AD |title=Whither triclosan? |journal=J. Antimicrob. Chemother. |volume=53 |issue=5 |pages=693–95 |date=May 2004 |pmid=15073159 |doi=10.1093/jac/dkh171|doi-access=free }}</ref> However, at the lower concentrations seen in commercial products, triclosan appears [[bacteriostatic]], and it targets bacteria primarily by inhibiting [[fatty acid metabolism#Synthesis|fatty acid synthesis]].{{citation needed|date=December 2022}}

Triclosan binds to bacterial [[enoyl-acyl carrier protein reductase]] (ENR) enzyme,<ref name="who06-99-triclosan">[https://www.who.int/patientsafety/information_centre/Last_April_versionHH_Guidelines%5B3%5D.pdf The WHO Guidelines on Hand Hygiene in Healthcare (Advanced Draft)], WHO, 2006, p. 37. "9.9 Triclosan"</ref> which is encoded by the gene ''fabI''. This binding increases the enzyme's affinity for [[nicotinamide adenine dinucleotide]] (NAD<sup>+</sup>). This results in the formation of a stable, ternary complex of ENR-NAD<sup>+</sup>-triclosan, which is unable to participate in [[fatty acid]] synthesis. Fatty acids are necessary for building and reproducing cell membranes. Vertebrates do not have an ENR enzyme and thus are not affected by this mode of action.{{citation needed|date=December 2022}}

Triclosan has also been reported to interact with [[tubulin]] and inhibit its polymerization.<ref>{{Cite journal | vauthors = Baksheeva VE, La Rocca R, Allegro D, Derviaux C, Pasquier E, Roche P, Morelli X, Devred F, Golovin AV, Tsvetkov PO | title = NanoDSF Screening for Anti-tubulin Agents Uncovers New Structure–Activity Insights | journal = Journal of Medicinal Chemistry | date = 2025 | doi = 10.1021/acs.jmedchem.5c01008 }}</ref>


===Endocrine disruptor===
Triclosan has been found to be a weak [[endocrine disruptor]], though the relevance of this to humans is uncertain.<ref name="pmid24897554">{{cite journal | vauthors = Witorsch RJ | title = Critical analysis of endocrine disruptive activity of triclosan and its relevance to human exposure through the use of personal care products | journal = Crit. Rev. Toxicol. | volume = 44 | issue = 6 | pages = 535–55 | year = 2014 | pmid = 24897554 | doi = 10.3109/10408444.2014.910754 | s2cid = 207505994 }}</ref><ref name="pmid20932229">{{cite journal | vauthors = Witorsch RJ, Thomas JA | title = Personal care products and endocrine disruption: A critical review of the literature | journal = Crit. Rev. Toxicol. | volume = 40 | pages = 1–30 | year = 2010 | issue = Suppl 3 | pmid = 20932229 | doi = 10.3109/10408444.2010.515563 | s2cid = 4653232 }}</ref> The compound has been found to bind with low [[affinity (pharmacology)|affinity]] to both the [[androgen receptor]] and the [[estrogen receptor]], where both [[agonist]]ic and [[receptor antagonist|antagonistic]] responses have been observed.<ref name="pmid24897554" />

===Efflux pump inducer===
Triclosan may upregulate or induce [[efflux pump]]s in bacteria causing them to become resistant against variety of other antibiotics.<ref>{{cite journal |last1=Shrestha |first1=Prabin |last2=Ni |first2=Jie |last3=Wong |first3=Tit-Yee |title=Synergistic and antagonistic interactions of triclosan with various antibiotics in bacteria |journal=Journal of Environmental Science and Health, Part C |date=2020 |volume=38 |issue=3 |pages=187–203 |doi=10.1080/26896583.2020.1781494 |pmid=32648520 |bibcode=2020JESHC..38..187S |s2cid=220474188 }}</ref><ref>{{cite journal |last1=Shrestha |first1=Prabin |last2=Zhang |first2=Yongmei |last3=Chen |first3=Wen-Jen |last4=Wong |first4=Tit-Yee |title=Triclosan: antimicrobial mechanisms, antibioticsinteractions, clinical applications, and human health |journal=Journal of Environmental Science and Health, Part C |date=2020 |volume=38 |issue=3 |pages=245–268 |doi=10.1080/26896583.2020.1809286 |pmid=32955413 |bibcode=2020JESHC..38..245S |s2cid=221825961 }}</ref>

==Exposure==
Humans are exposed to triclosan through skin absorption when washing hands or in the shower, brushing teeth, using mouthwash or doing dishes, and through ingestion when swallowed. When triclosan is released into the environment, additional exposure to the chemical is possible through ingesting plants grown in soil treated with [[sewage sludge]], or eating fish exposed to it.<ref name=halden/>

An article from the [[American Society of Agronomy]] refers to a study done by Monica Mendez ''et al.'', in which the researchers irrigated plants with water containing triclosan and months later found it in all edible parts of [[tomato]] and [[onion]] plants.<ref>{{cite journal | last1 = Mendez | first1 = Monica O. | last2 = Valdez | first2 = Erika M. | last3 = Martinez | first3 = Eileen M. | last4 = Saucedo | first4 = Melissa | last5 = Wilson | first5 = Brittan A. | year = 2016 | title = Fate of Triclosan in Irrigated Soil: Degradation in Soil and Translocation into Onion and Tomato | journal = Journal of Environmental Quality | volume = 45 | issue = 3| pages = 1029–35 | doi = 10.2134/jeq2015.07.0386 | pmid = 27136171 | bibcode = 2016JEnvQ..45.1029M }}</ref> Triclosan is found to kill a wide spectrum of bacteria, and the researchers are also concerned about the effect it has on the beneficial bacteria in soil.<ref>{{Cite web |title=Search {{!}} American Society of Agronomy |url=https://www.agronomy.org/search/404/science%20news%20following%20tricky%20triclosan/ |access-date=2023-05-26 |website=www.agronomy.org}}</ref>

==Distribution, metabolism, and elimination==
Once absorbed, triclosan is metabolized by humans primarily through conjugation reactions into [[glucuronide]] and [[sulfate conjugates]] that are excreted in feces and urine. Pharmacokinetic studies demonstrate that triclosan sulfate and glucuronide may be formed in the liver at approximately equal rates at the environmentally relevant concentration of 1 to 5 microMolar. When concentrations of triclosan are below 1 microMolar, [[sulfonation]] is expected to be the major metabolic pathway for elimination.<ref name="Yueh et al 2016">{{cite journal |last1=Yueh |first1=Mei-Fei |last2=Tukey |first2=Robert H. |title=Triclosan: A Widespread Environmental Toxicant with Many Biological Effects |journal=Annual Review of Pharmacology and Toxicology |date=6 January 2016 |volume=56 |issue=1 |pages=251–272 |doi=10.1146/annurev-pharmtox-010715-103417 |pmid=26738475 |pmc=4774862 }}</ref>

==Health concerns==
Because of potential health concerns, due to the possibility of antimicrobial resistance, endocrine disruption and other issues as listed below, triclosan has been designated as a "contaminant of emerging concern (CEC)" by the [[United States Geological Survey]], meaning it is under investigation for public health risk. "Emerging contaminants" can be broadly defined as any synthetic or naturally occurring chemical or any microorganism that is not commonly monitored in the environment but has the potential to enter the environment and cause known or suspected adverse ecological or human health effects.<ref>United States Geological Survey. Contaminants of Emerging Concern in the Environment. Retrieved October 27, 2016, from https://toxics.usgs.gov/investigations/cec/index.php {{Webarchive|url=https://web.archive.org/web/20161029112108/http://toxics.usgs.gov/investigations/cec/index.php |date=2016-10-29 }}</ref> Triclosan is thought to accumulate in wastewater and return to drinking water, thus propagating a buildup that could cause increasing effects with ongoing use.<ref>{{Cite journal |last=Commissioner |first=Office of the |date=2020-09-09 |title=5 Things to Know About Triclosan |url=https://www.fda.gov/consumers/consumer-updates/5-things-know-about-triclosan |archive-url=https://web.archive.org/web/20190507072630/https://www.fda.gov/consumers/consumer-updates/5-things-know-about-triclosan |archive-date=May 7, 2019 |journal=FDA |language=en}}</ref>

In the United States, after a decades-long review of the potential health issues from this contaminant of emerging concern, the FDA ruled on September 6, 2016, that 19 active ingredients including triclosan are not generally recognized as safe and effective (GRAS/GRAE).<ref>{{Cite web |date=2020-03-24 |title=FDA issues final rule on safety and effectiveness of antibacterial soaps |url=https://www.fda.gov/news-events/press-announcements/fda-issues-final-rule-safety-and-effectiveness-antibacterial-soaps |archive-url=https://web.archive.org/web/20190531095358/https://www.fda.gov/news-events/press-announcements/fda-issues-final-rule-safety-and-effectiveness-antibacterial-soaps |archive-date=May 31, 2019 |access-date=2023-08-17 |website=FDA |language=en}}</ref> (See [[Triclosan#Policy|policy]] section below).

===Allergic===
Triclosan has been associated with a higher risk of [[food allergy]].<ref>{{cite journal |doi=10.1016/j.jaci.2012.11.007 |pmid=23199604 |title=Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2012 |journal=Journal of Allergy and Clinical Immunology |volume=131 |issue=1 |pages=55–66 |year=2013 |last1=Sicherer |first1=Scott H. |last2=Leung |first2=Donald Y.M.|doi-access=free }}</ref> This may be because exposure to bacteria reduces [[allergy|allergies]], as predicted by the [[hygiene hypothesis]], and not caused by toxicology of triclosan itself. This effect may also occur with [[chlorhexidine|chlorhexidine gluconate]] and [[chloroxylenol]] (PCMX), among other antibacterial agents.<ref name="Clayton-2010">{{cite journal|last1=Clayton|first1=Erin M. Rees|last2=Todd|first2=Megan|last3=Dowd|first3=Jennifer Beam|author-link3=Jennifer Dowd|last4=Aiello|first4=Allison E.|year=2010|title=The Impact of Bisphenol a and Triclosan on Immune Parameters in the U.S. Population, NHANES 2003–2006|journal=Environmental Health Perspectives|volume=119|issue=3|pages=390–96|doi=10.1289/ehp.1002883|pmc=3060004|pmid=21062687}}
* {{cite press release |date=November 30, 2010 |title=Antibacterial soaps: Being too clean can make people sick, study suggests |website=ScienceDaily |url=https://www.sciencedaily.com/releases/2010/11/101129101920.htm}}</ref><ref>{{cite news |first=April |last=Fulton |date=November 29, 2010 |url=https://www.npr.org/blogs/health/2010/11/29/131670317/new-questions-raised-on-chemicals-in-soaps-plastics?ft=1&f=1007 |title=New Questions Raised On Chemicals In Soaps, Plastics |newspaper=NPR |access-date=2010-11-30}}</ref> Other studies have linked triclosan to allergic [[contact dermatitis]] in some individuals.<ref name="Bhutani-2009">{{cite journal |doi=10.1111/j.1524-4725.2009.01151.x |pmid=19389086 |title=Triclosan |journal=Dermatologic Surgery |volume=35 |issue=5 |pages=888–89 |year=2009 |last1=Bhutani |first1=Tina |last2=Jacob |first2=Sharon E.}}</ref><ref name="Campbell-2006">{{cite journal |doi=10.2310/6620.2006.06014 |pmid=17150172 |title=Triclosan |journal=Dermatitis |volume=17 |issue=4 |pages=204–07 |year=2006 |last1=Campbell |first1=Lauren |last2=Zirwas |first2=Matthew J. |last3=Mowad |first3=Christen M.|s2cid=220577352 }}</ref> Additionally, triclosan concentrations have been associated with allergic sensitization, especially inhalant and seasonal allergens, rather than food allergens.<ref>{{cite journal |doi=10.1111/all.12058 |pmid=23146048 |pmc=3515701 |title=Triclosan exposure and allergic sensitization in Norwegian children |journal=Allergy |volume=68 |issue=1 |pages=84–91 |year=2013 |last1=Bertelsen |first1=R.J. |last2=Longnecker |first2=M.P. |last3=Løvik |first3=M. |last4=Calafat |first4=A.M. |last5=Carlsen |first5=K-H. |last6=London |first6=S.J. |last7=Lødrup Carlsen |first7=K.C.|author6-link=Stephanie J. London}}</ref>

===By-product exposure===
Triclosan can react with the free [[chlorine]] in [[Water chlorination|chlorinated tap water]] to produce lesser amounts of other compounds, such as [[2,4-dichlorophenol]]. Some of these intermediates convert into [[polychlorinated dibenzodioxins|dioxins]] upon exposure to [[UV]] radiation (from the sun or other sources).<ref>{{cite journal |doi=10.1007/s11356-011-0632-z |pmid=22057832 |title=Occurrence and toxicity of antimicrobial triclosan and by-products in the environment |journal=Environmental Science and Pollution Research |volume=19 |issue=4 |pages=1044–65 |year=2011 |last1=Bedoux |first1=Gilles |last2=Roig |first2=Benoit |last3=Thomas |first3=Olivier |last4=Dupont |first4=Virginie |last5=Le Bot |first5=Barbara|s2cid=35106807 }}</ref> The dioxins that can form from triclosan are not thought to be congeners of toxicologic concern for mammals, birds and fish.<ref name=EPA2013>{{cite web |publisher=Environmental Protection Agency |url=http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2012-0811-0002 |title=Triclosan Registration Review Preliminary Work Plan |date=27 March 2013}}</ref><ref name=WHO>{{cite journal |doi=10.1080/713810655 |pmid=10912238 |title=Consultation on assessment of the health risk of dioxins; re-evaluation of the tolerable daily intake (TDI): Executive Summary |journal=Food Additives and Contaminants |volume=17 |issue=4 |pages=223–40 |year=2000 |last1=van den Berg |first1=M |last2=van Birgelen |first2=A |last3=Birnbaum |first3=L |last4=Brouwer |first4=B |last5=Carrier |first5=G |last6=Dragan |first6=Y |last7=Farland |first7=W |last8=Feeley |first8=M |last9=Fýrst |first9=P |last10=Galli |first10=CL |last11=Greig |first11=J |last12=Hayashi |first12=Y |last13=Kogevinas |first13=M |last14=Kurokawa |first14=Y |last15=Larsen |first15=JC |last16=Liem |first16=AKD |last17=Matsumura |first17=F |last18=Mocarelli |first18=P |last19=Moore |first19=MR |last20=Newhook |first20=RC |last21=Peterson |first21=RE |last22=Poellinger |first22=L |last23=Portier |first23=C |last24=Rogan |first24=WJ |last25=Schrenk |first25=D |last26=Sweeney |first26=MH |last27=Tohyama |first27=C |last28=Tuomisto |first28=J |last29=Water |first39=J |last30=Zeilmaker |first30=M|s2cid=216644694 }}</ref>

===Hormonal===
Concerns on the health effects of triclosan have been raised after it was detected in human breast milk, blood, and urine samples. Studies on rats have shown that triclosan exposure modulates estrogen-dependent responses.<ref>{{cite journal |last1=Stoker |first1=Tammy E. |last2=Gibson |first2=Emily K. |last3=Zorrilla |first3=Leah M. |title=Triclosan Exposure Modulates Estrogen-Dependent Responses in the Female Wistar Rat |journal=Toxicological Sciences |date=September 2010 |volume=117 |issue=1 |pages=45–53 |doi=10.1093/toxsci/kfq180 |pmid=20562219 |doi-access=free }}</ref> There have been many studies performed over the years both in vivo and in vitro, in male and female fish and rats and they support the conclusion that triclosan possesses (anti)estrogenic and (anti)androgenic properties depending on species, tissues, and cell types.<ref name="Yueh et al 2016"/>

Human studies on triclosan and hormone effects are fewer in number than those on animals, but are being conducted. In a 2017 study on 537 pregnant women in China, prenatal triclosan exposure was associated with increased cord [[testosterone]] levels in the infants.<ref>{{cite journal |last1=Wang |first1=Caifeng |last2=Chen |first2=Limei |last3=Zhao |first3=Shasha |last4=Hu |first4=Yi |last5=Zhou |first5=Yijun |last6=Gao |first6=Yu |last7=Wang |first7=Weiye |last8=Zhang |first8=Jun |last9=Tian |first9=Ying |title=Impacts of prenatal triclosan exposure on fetal reproductive hormones and its potential mechanism |journal=Environment International |date=February 2018 |volume=111 |pages=279–286 |doi=10.1016/j.envint.2017.11.007 |pmid=29150338 |bibcode=2018EnInt.111..279W }}</ref>

==History==
Triclosan (TCS) was patented in 1964<ref name=halden/> by Swiss company [[Ciba-Geigy]]. The earliest known safety testing began in 1968.<ref>{{cite news | last=Kary | first=Tiffany | title=Cancer-Linked Colgate Total Ingredient Suggests FDA Flaws | date=August 11, 2014 | url=https://www.bloomberg.com/news/articles/2014-08-11/in-35-pages-buried-at-fda-worries-over-colgate-s-total | newspaper=Bloomberg.com | access-date=October 29, 2016}} From embedded infographic: [https://www.bloomberg.com/graphics/infographics/triclosan-four-decades-of-regulatory-limbo.html Triclosan: Four Decades of Regulatory Limbo]</ref> It was introduced the next year, mainly for use in hospitals, and was in worldwide production and use by the early 1970s.

In 1997 Ciba-Geigy merged with another Swiss company, [[Sandoz]], to form [[Novartis]].<ref name="novhist">{{Citation |title=Company history  |work=corporate website  |at=novartis.com  |publisher=Novartis  |url=http://www.novartis.com/about-novartis/company-history/index.shtml |archive-url=https://web.archive.org/web/20101230203847/http://www.novartis.com/about-novartis/company-history/index.shtml  |archive-date=30 December 2010  |df=dmy}}</ref> During the merger, Ciba-Geigy's chemical business was spun off to become [[Ciba Specialty Chemicals]], which was acquired in 2008 by chemical giant [[BASF]]. BASF currently manufactures TCS under the brand name Irgasan DP300.<ref>{{cite web | title=Homecare and I & I: Irgasan DP 300 | url=http://www.homecare-and-i-and-i.basf.com/ProductDetails?PRD=30338761 | website=BASF.com | access-date=October 29, 2016 | archive-date=October 29, 2016 | archive-url=https://web.archive.org/web/20161029112102/http://www.homecare-and-i-and-i.basf.com/ProductDetails?PRD=30338761 }}</ref>

==Environmental concerns==

===Treatment and disposal===
Exposure to triclosan in personal product use is relatively short. Upon disposal, triclosan is sent to municipal [[sewage treatment]] plants, where, in the United States, about 97–98% of triclosan is removed.<ref name=halden>{{cite journal |doi=10.1021/es500495p |pmid=24588513 |pmc=3974611 |title=On the Need and Speed of Regulating Triclosan and Triclocarban in the United States |journal=Environmental Science & Technology |volume=48 |issue=7 |pages=3603–11 |year=2014 |last1=Halden |first1=Rolf U. |bibcode=2014EnST...48.3603H}}</ref> Studies show that substantial quantities of triclosan (170,000–970,000&nbsp;kg/yr) can escape from wastewater treatment plants and damage algae on surface waters.<ref name=halden/> In a study on [[effluent]] from wastewater treatment facilities, approximately 75% of triclocarban was present in [[sewage sludge]].<ref>{{cite journal |doi=10.1016/j.envint.2010.06.004 |pmid=20797791 |title=Review of 'emerging' organic contaminants in biosolids and assessment of international research priorities for the agricultural use of biosolids |journal=Environment International |volume=37 |issue=1 |pages=226–47 |year=2011 |last1=Clarke |first1=Bradley O. |last2=Smith |first2=Stephen R.|bibcode=2011EnInt..37..226C }}</ref> This poses a potential environmental and ecological hazard, particularly for aquatic systems. The volume of triclosan, in the United States, re-entering the environment in [[sewage]] sludge after initial successful capture from wastewater is 44,000 ± 60,000&nbsp;kg/yr.<ref name=halden/> Triclosan can attach to other substances suspended in aquatic environments, which potentially endangers marine organisms and may lead to further bioaccumulation.<ref name=tf>{{cite web |url=http://www.epa.gov/oppsrrd1/REDs/factsheets/triclosan_fs.htm |archive-url=https://web.archive.org/web/20080619011328/http://www.epa.gov/oppsrrd1/REDs/factsheets/triclosan_fs.htm |archive-date=June 19, 2008 |title=Triclosan Facts |publisher=Environmental Protection Agency |access-date=17 Feb 2014}}</ref> [[Ozone]] is considered to be an effective tool for removing triclosan during sewage treatment. As little triclosan is released through [[plastics|plastic]] and textile household consumer products, these are not considered to be major sources of triclosan contamination.<ref name=tf/>

During wastewater treatment, a portion of triclosan is degraded, while the remainder adsorbs to sewage [[sludge]] or exits the plant as effluent.<ref name="pmid12523412">{{cite journal |doi=10.1021/es025750i |pmid=12523412 |title=Triclosan: Occurrence and Fate of a Widely Used Biocide in the Aquatic Environment: Field Measurements in Wastewater Treatment Plants, Surface Waters, and Lake Sediments |journal=Environmental Science & Technology |volume=36 |issue=23 |pages=4998–5004 |year=2002 |last1=Singer |first1=Heinz |last2=Müller |first2=Stephan |last3=Tixier |first3=Céline |last4=Pillonel |first4=Laurent |bibcode=2002EnST...36.4998S}}</ref><ref name="pmid16766013">{{cite journal |doi=10.1016/j.chemosphere.2006.04.066 |pmid=16766013 |title=Mass balance assessment of triclosan removal during conventional sewage treatment |journal=Chemosphere |volume=66 |issue=2 |pages=362–69 |year=2007 |last1=Heidler |first1=Jochen |last2=Halden |first2=Rolf U.|bibcode=2007Chmsp..66..362H }}</ref> A mass balance in Athens (Greece) Sewage Treatment Plant (2013) showed that 43% of triclosan is accumulated to the primary and secondary sludge, 45% is lost due to degradation while the rest 12% is discharged to the environment via the secondary treated wastewater.<ref>{{cite journal |last1=Stasinakis |first1=Athanasios S. |last2=Thomaidis |first2=Nikolaos S. |last3=Arvaniti |first3=Olga S. |last4=Asimakopoulos |first4=Alexandros G. |last5=Samaras |first5=Vasilios G. |last6=Ajibola |first6=Akinranti |last7=Mamais |first7=Daniel |last8=Lekkas |first8=Themistokles D. |title=Contribution of primary and secondary treatment on the removal of benzothiazoles, benzotriazoles, endocrine disruptors, pharmaceuticals and perfluorinated compounds in a sewage treatment plant |journal=Science of the Total Environment |date=October 2013 |volume=463-464 |pages=1067–1075 |doi=10.1016/j.scitotenv.2013.06.087 |pmid=23891999 |bibcode=2013ScTEn.463.1067S }}</ref> In the environment, triclosan may be degraded by microorganisms or react with sunlight, forming other compounds, which include chlorophenols and [[polychlorinated dibenzodioxins|dioxins]].{{citation needed|date=December 2022}}

During 1999 to 2000, US Geological Survey detected TCS in 57.6% of streams and rivers sampled.<ref name="Dhillon et al 2015">{{cite journal |last1=Dhillon |first1=Gurpreet |last2=Kaur |first2=Surinder |last3=Pulicharla |first3=Rama |last4=Brar |first4=Satinder |last5=Cledón |first5=Maximiliano |last6=Verma |first6=Mausam |last7=Surampalli |first7=Rao |title=Triclosan: Current Status, Occurrence, Environmental Risks and Bioaccumulation Potential |journal=International Journal of Environmental Research and Public Health |date=22 May 2015 |volume=12 |issue=5 |pages=5657–5684 |doi=10.3390/ijerph120505657 |pmid=26006133 |pmc=4454990 |doi-access=free }}</ref>

===Bioaccumulation===
While studies using semi-permeable membrane devices have found that triclosan does not strongly [[Bioaccumulation|bioaccumulate]], [[methyl-triclosan]] is comparatively more stable and [[lipophilicity|lipophilic]] and thus poses a higher risk of bioaccumulation. The ability of triclosan to bioaccumulate is affected by its ionization state in different environmental conditions.<ref>{{cite journal |last1= Brausch |first1= John |last2= Rand |first2= Gary |year= 2011 |title= A review of personal care products in the aquatic environment: Environmental concentrations and toxicity |journal= [[Chemosphere (journal)|Chemosphere]] |volume= 82 |issue= 11 |pages= 1518–32 |doi= 10.1016/j.chemosphere.2010.11.018|pmid= 21185057 |bibcode= 2011Chmsp..82.1518B }}</ref>

[[Global warming]] may increase uptake and effects of triclosan in aquatic organisms.<ref>{{cite journal |last1=Hedrick-Hopper |first1=Tiffany L. |last2=Koster |first2=Lauren P. |last3=Diamond |first3=Sandra L. |title=Accumulation of triclosan from diet and its neuroendocrine effects in Atlantic croaker (Micropogonias undulatus) under two temperature Regimes |journal=Marine Environmental Research |date=December 2015 |volume=112 |issue=Pt A |pages=52–60 |doi=10.1016/j.marenvres.2015.09.006 |pmid=26446583 |bibcode=2015MarER.112...52H }}</ref>

===Ecotoxicity===
{{Further|Ecotoxicity}}
Triclosan is toxic to aquatic bacteria at levels found in the environment. It is highly toxic to various types of algae and has the potential to affect the structure of algal communities, particularly immediately downstream of effluents from [[wastewater treatment]] facilities that treat household wastewaters.<ref>{{cite web |url=http://www.oehha.org/prop65/public_meetings/052909coms/triclosan/ciba12.pdf |title=Estimates Of Exposures And Risks To Aquatic Organisms From Releases Of Triclosan To Surface Water As A Result Of Uses Under EPA'S Jurisdiction |access-date=2014-09-22 |archive-date=2010-11-27 |archive-url=https://web.archive.org/web/20101127104239/http://oehha.org/prop65/public_meetings/052909coms/triclosan/ciba12.pdf }}</ref> Triclosan has been observed in multiple organisms, including algae, aquatic [[Lumbriculus variegatus|blackworms]], fish, and [[dolphin]]s. It has also been found in land animals including earthworms and species higher up the [[food chain]].<ref name=halden/> In toxicity experiments with ''Vibrio fischeri'' marine bacterium, an EC50 value of TCS equal to 0.22&nbsp;mg/L has been determined.<ref>{{cite journal |last1=Stasinakis |first1=Athanasios S. |last2=Mamais |first2=Daniel |last3=Thomaidis |first3=Nikolaos S. |last4=Danika |first4=Elena |last5=Gatidou |first5=Georgia |last6=Lekkas |first6=Themistokles D. |title=Inhibitory effect of triclosan and nonylphenol on respiration rates and ammonia removal in activated sludge systems |journal=Ecotoxicology and Environmental Safety |date=June 2008 |volume=70 |issue=2 |pages=199–206 |doi=10.1016/j.ecoenv.2007.12.011 |pmid=18237779 |bibcode=2008EcoES..70..199S }}</ref> Few data are available for the long-term toxicity of TCS to algae, daphnids and fish, while enough data are available for its acute toxicity on these groups of organisms.{{citation needed|date=December 2022}}

A 2017 study that used risk quotient (RQ) methodology and evaluated the ecological threat due to the discharge of wastewater containing TCS in European rivers, reported that the probability that RQ values exceeds 1 ranged from 0.2% (for rivers with dilution factor of 1000) to 45% (for rivers with dilution factor 2).<ref>{{cite journal |last1=Thomaidi |first1=Vasiliki S. |last2=Matsoukas |first2=Christos |last3=Stasinakis |first3=Athanasios S. |title=Risk assessment of triclosan released from sewage treatment plants in European rivers using a combination of risk quotient methodology and Monte Carlo simulation |journal=Science of the Total Environment |date=December 2017 |volume=603-604 |pages=487–494 |doi=10.1016/j.scitotenv.2017.06.113 |pmid=28641188 |bibcode=2017ScTEn.603..487T }}</ref>

Triclosan favors anaerobic conditions which is typical in soil and sediment. The antimicrobial properties of Triclosan are resistant to anaerobic degradation which is the main contributor to its persistence in the environment.<ref>{{cite journal |last1=Dann |first1=Andrea B. |last2=Hontela |first2=Alice |title=Triclosan: environmental exposure, toxicity and mechanisms of action |journal=Journal of Applied Toxicology |date=May 2011 |volume=31 |issue=4 |pages=285–311 |doi=10.1002/jat.1660 |pmid=21462230 |s2cid=30753558 }}</ref>

==Resistance concerns==
{{missing information|section|resistance mechanism, if any known|date=July 2022}}
Concern pertains to the potential for [[cross-resistance]] (or co-resistance) to other antimicrobials. Numerous studies have been performed and there have been results indicating that the use of biocidal agents, such as triclosan, can cause cross-resistance.
A study done in a wide range of bacteria and different classes of antibiotics showed that ''[[Pseudomonas aeruginosa]]'' and ''[[Stenotrophomonas maltophilia]]'', already resistant to triclosan, had increased resistance against antibiotics tetracycline and norfloxacin when exposed to triclosan.<ref>{{cite journal |last1=Shrestha |first1=Prabin |last2=Ni |first2=Jie |last3=Wong |first3=Tit-Yee |title=Synergistic and antagonistic interactions of triclosan with various antibiotics in bacteria |journal=Journal of Environmental Science and Health, Part C |date=2020 |volume=38 |issue=3 |pages=245–268 |doi=10.1080/26896583.2020.1781494 |pmid=32648520 |bibcode=2020JESHC..38..187S |s2cid=220474188 }}</ref>
Results from a study published in ''The American Journal of Infection Control'' showed that exposure to triclosan was associated with a high risk of developing resistance and cross-resistance in ''[[Staphylococcus aureus]]'' and ''[[Escherichia coli]]''. This was not observed with exposure to [[chlorhexidine]] or a hydrogen [[peroxide]]-based agent (during the conditions in said study).<ref name="pmid26810885">{{cite journal |doi=10.1016/j.ajic.2015.11.009 |pmid=26810885 |title=Use of a predictive protocol to measure the antimicrobial resistance risks associated with biocidal product usage |journal=American Journal of Infection Control |volume=44 |issue=4 |pages=458–64 |year=2016 |last1=Westgate |first1=Rebecca |last2=Grasha |first2=Pierre |last3=Maillard |first3=Jean-Yves |doi-access=free }}</ref>

==Alternatives==
A comprehensive [[meta-analysis]] published in 2007 indicated that, in community settings, plain soap was no less effective than soaps containing triclosan for "preventing infectious illness symptoms and reducing bacterial levels on the hands.".<ref>{{cite journal |doi=10.1086/519255 |pmid=17683018 |title=Consumer Antibacterial Soaps: Effective or Just Risky? |journal=Clinical Infectious Diseases |volume=45 |pages=S137–47 |year=2007 |last1=Aiello |first1=A.E. |last2=Larson |first2=E.L. |last3=Levy |first3=S.B. |hdl=2027.42/55477 |hdl-access=free |doi-access=free}}
* {{cite web |date=August 15, 2007 |title=Plain soap as effective as antibacterial but without the risk |website=Phys.org |url=http://phys.org/news106418144.html}}</ref>

Nonorganic antibiotics and organic biocides are effective alternatives to triclosan, such as silver and copper ions and [[nanoparticle]]s.<ref>{{cite journal |doi=10.1016/j.nano.2006.12.001 |pmid=17379174 |title=Antimicrobial effects of silver nanoparticles |journal=Nanomedicine: Nanotechnology, Biology and Medicine |volume=3 |issue= 1|pages=S137–47 |year=2007 |last1=Kim |first1=Jun Sung |last2=Kuk |first2=Eunye |last3=Yu |first3=Kyeong Nam |last4=Kim |first4=Jong-Ho |last5=Park |first5=Sung Jin |last6=Lee |first6=Hu Jang |last7=Kim |first7=So Hyun |last8=Park |first8=Young Kyung |last9=Park |first9=Yong Ho |last10=Hwang |first10=Cheol-Yong |last11=Kim |first11=Yong-Kwon |last12=Lee |first12=Yoon-Sik |last13=Jeong |first13=Dae Hong |last14=Cho |first14=Myung-Haing |hdl=10371/8335 |hdl-access=free }}</ref>

==Policy==
In the US, triclosan is regulated as a pesticide by the EPA and as a drug by the FDA. The EPA generally regulates uses on solid surfaces, and FDA regulations cover uses in personal care products.{{citation needed|date=December 2022}}

In 1974, the US FDA began the drug review monograph process for "over-the-counter (OTC) topical antimicrobial products", including triclosan and triclocarban. The advisory panel first met on June 29, 1972, and the agency published its proposed rule on Sept 13, 1974. The initial rule applied to, "OTC products containing antimicrobial ingredients for topical human use, which includes soaps, surgical scrubs, skin washes, skin cleansers, first aid preparations and additional products defined by the panel."<ref>Proposal to Establish a Monograph for OTC Topical Antimicrobial Products. Federal Register, vol. 39, no. 179. September 13, 1974. [https://web.archive.org/web/20090710142303/http://www.fda.gov/downloads/Drugs/DevelopmentApprovalProcess/DevelopmentResources/Over-the-CounterOTCDrugs/StatusofOTCRulemakings/ucm107140.pdf]
</ref> The proposed rule lists dozens of products that were already on the market at the time and the firms that produced them.{{citation needed|date=December 2022}}

In 1978 the FDA published a tentative final monograph (TFM) for topical antimicrobial products. The record was re-opened in March 1979 to take into account six comments the agency received during the period for submitting objections to the TFM, including new data submitted by Procter & Gamble on the safety and effectiveness of triclocarban and by Ciba-Geigy on the proliferation of use of triclosan. The document states that, "significant amounts of new and previously unconsidered data were submitted with each of the above petitions."<ref>Topical Antimicrobial Products for Over-the-Counter Human Use: Reopening of the Administrative Record. Federal Register, vol. 44, no. 48. March 9, 1979. [https://web.archive.org/web/20090710142323/http://www.fda.gov/downloads/Drugs/DevelopmentApprovalProcess/DevelopmentResources/Over-the-CounterOTCDrugs/StatusofOTCRulemakings/UCM107157.pdf]</ref> It was re-opened again in October of that year to permit interested persons to submit further data establishing conditions for the safety, effectiveness and labeling of over-the-counter topical antimicrobial products for human use.{{citation needed|date=December 2022}}

The next document issued was a proposed rule dated June 17, 1994, which states, the "FDA is issuing a notice of proposed rulemaking in the form of an amended tentative final monograph that would establish conditions under which OTC topical health-care antiseptic drug products are generally recognized as safe and effective and not misbranded. The FDA is issuing this notice of proposed rulemaking on topical antimicrobial drug products after considering the public comments on that notice and other information in the administrative record for this rulemaking. The FDA is also requesting data and information concerning the safety and effectiveness of topical antimicrobials for use as hand sanitizers or dips."<ref>Topical Antimicrobial Drug Products for Over-the-Counter Human Use. Federal Register, vol. 59, no. 116. June 17, 1994. [https://web.archive.org/web/20090710142405/http://www.fda.gov/downloads/Drugs/DevelopmentApprovalProcess/DevelopmentResources/Over-the-CounterOTCDrugs/StatusofOTCRulemakings/UCM110451.pdf]</ref> In the 1994 update to the rule, TCS was effectively removed from the drug category which made it available for use in consumer products.<ref name=halden/>

In 2010, the [[Natural Resources Defense Council]] forced the FDA to review triclosan after suing the agency for its inaction. Because the FDA prohibited [[hexachlorophene]], a compound similar to triclosan, Halden and others argued that the FDA should also ban triclosan.<ref name=halden/> On December 17, 2013, the FDA issued a draft rule revoking the [[generally recognized as safe]] status of triclosan as an ingredient in hand wash products, citing the need for additional studies of its potential endrocrine and developmental effects; impact on bacterial resistance; and carcinogenic potential.<ref>{{cite web |url=http://www.gpo.gov/fdsys/pkg/FR-2013-12-17/pdf/2013-29814.pdf |title=Federal Register |access-date=2014-09-22}}</ref>

On September 6, 2016, 44 years after its initial proposed rule, the FDA issued a final rule establishing that 19 active ingredients, including triclosan and triclocarban, used in over-the-counter (OTC) consumer antiseptic products intended for use with water (aka consumer antiseptic washes) are not generally recognized as safe and effective (GRAS/GRAE) and are misbranded, and are new drugs for which approved applications under section 505 of the FD&C Act are required for marketing.<ref>Safety and Effectiveness of Consumer Antiseptics; Topical Antimicrobial Drug Products for Over-the-Counter Human Use. Federal Register, vol. 81, no. 172. September 6, 2016. https://www.gpo.gov/fdsys/pkg/FR-2016-09-06/pdf/2016-21337.pdf</ref> Companies have one year to reformulate products without these ingredients, take them off the market or submit a New Drug Application (NDA) for the products. The 19 ingredients are:
* [[Cloflucarban]]
* [[Fluorosalan]]
* [[Hexachlorophene]]
* [[Hexylresorcinol]]
* Iodine complex (ammonium ether sulfate and polyoxyethylene sorbitan monolaurate)
* Iodine complex (phosphate ester of alkylaryloxy polyethylene glycol)
* [[Methylbenzethonium chloride]]
* Nonylphenoxypoly (ethyleneoxy) ethanoliodine
* [[Phenol]] (greater than 1.5 percent)
* Phenol (less than 1.5 percent)
* [[Poloxamer]]-iodine complex
* [[Povidone-iodine]] 5 to 10 percent
* Secondary [[amyltricresols]]
* [[Sodium oxychlorosene]]
* [[Tribromsalan]]
* [[Triclocarban]]
* Triclosan
* [[Triple dye]] (an antiseptic applied to the [[umbilical region]] of newborn infants<ref>{{cite journal |last1=Roth |first1=Philip |title=Neonatology |journal=Pediatric Secrets |date=2011 |pages=423–479 |doi=10.1016/B978-0-323-06561-0.00012-4|isbn=978-0-323-06561-0 }}</ref>)
* [[Undecoylium chloride]] iodine complex

In 2015 and 2016 FDA also issued proposed rules to amend the 1994 TFM regarding the safety and effectiveness of OTC health care antiseptics and OTC consumer antiseptic rubs.

The state of Minnesota took action against triclosan in advance of a federal rule. In May 2014, the governor signed a bill banning triclosan-containing products in the state. A ''CNN'' article quotes the new law, "In order to prevent the spread of infectious disease and avoidable infections and to promote best practices in sanitation, no person shall offer for retail sale in Minnesota any cleaning product that contains triclosan and is used by consumers for sanitizing or hand and body cleansing."<ref>Landau, Elizabeth and Young, Saundra. (May 21, 2014). Minnesota issues ban on antibacterial ingredient. CNN. Retrieved from http://www.cnn.com/2014/05/21/health/triclosan-ban-antibacterial/</ref> The law goes into effect on January 1, 2017. The exceptions to this rule are individual products that have received approval from the US Food and Drug Administration for consumer use.

In light of mounting evidence on the human health and ecotoxic effects of triclosan, some companies reformulated to remove it in advance of regulation: Colgate-Palmolive removed it from Palmolive Dish Soap and Softsoap in 2011 (but it remained in Colgate Total toothpaste until late 2018 or early 2019<ref>{{Cite web|url=https://qz.com/1540815/colgate-eliminated-triclosan-from-its-toothpaste-could-a-ban-be-on-the-way/|title=Colgate eliminated triclosan from its toothpaste. Could a ban be on the way?|last=Purtill|first=Corinne|date=February 2, 2019|website=Quartz|language=en|access-date=June 26, 2019}}</ref>); Johnson & Johnson removed it from baby products in 2012 and all products in 2015; Procter & Gamble from all products in 2014; in 2014 it was removed from Clearasil and Avon began phasing it out; and Unilever removed it from skin care and cleansing products in 2015, and says oral care by 2017.<ref>{{Cite news |title=Triclosan: Four Decades of Regulatory Limbo |language=en |work=Bloomberg.com |url=https://www.bloomberg.com/graphics/infographics/triclosan-four-decades-of-regulatory-limbo.html |access-date=2023-08-17}}
</ref>

In Canada, triclosan is allowed in cosmetics, though FDA's recent announcement has prompted Health Canada spokeswoman Maryse Durette to state in an e-mail to Toronto newspaper ''The Globe and Mail'' that, "the government will publish a final assessment of the safety of triclosan 'in the near future' and take further action 'if warranted.{{'"}}<ref>{{Cite news |date=2016-09-06 |title=The FDA will ban antibacterial ingredients from soaps. What about Canada? |language=en-CA |work=The Globe and Mail |url=https://www.theglobeandmail.com/life/health-and-fitness/health/the-fda-will-ban-antibacterial-ingredients-from-soaps-what-about-canada/article31729886/ |access-date=2023-08-17}}
</ref> Health Canada maintains a Cosmetic Ingredient Hotlist, including hundreds of chemicals that are not allowed or whose use is restricted in cosmetics. The list states that triclosan is currently allowed in cosmetics up to 0.3%, and 0.03% in mouthwashes and other oral products with required warnings to avoid swallowing and not for use in children under the age of 12.<ref>Consumer Ingredient Hotlist. Health Canada website. Retrieved October 20, 2016, http://www.hc-sc.gc.ca/cps-spc/cosmet-person/hot-list-critique/hotlist-liste-eng.php
</ref>

Triclosan was not approved by the European Commission as an active substance for use in biocidal products for product-type 1 in January 2016.<ref>{{cite web|url=http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=uriserv:OJ.L_.2016.021.01.0086.01.ENG&toc=OJ:L:2016:021:FULL|title=EUR-Lex – 32016D0110 – EN – EUR-Lex|website=eur-lex.europa.eu|access-date=8 September 2017}}</ref> In the United States, manufacturers of products containing triclosan must indicate its presence on the label. In Europe, triclosan is regulated as a cosmetic preservative and must be listed on the label.<ref>{{cite web |title=REGULATION (EC) No 1223 /2009 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 30 November 2009 on cosmetic products|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2009:342:0059:0209:en:PDF|website=Official Journal of the European Union|year=2009}}</ref> Use of triclosan in cosmetic products was restricted by the EU commission in 2014.<ref>Commission Regulation (EU) No 358/2014 of 9 April 2014</ref>

==See also==
{{columns-list|colwidth=30em|
* [[Antibacterial soap]]
* [[Benzalkonium chloride]]
* [[Breast cancer]]
* [[Chloroform]]
* [[Chloroxylenol]]
* [[Dial (soap)]]
* [[Hand sanitizer]]
* [[Simple aromatic ring]]
}}

==References==
{{Reflist}}

{{Antiseptics and disinfectants}}
{{Medicated dressings}}
{{Androgen receptor modulators}}
{{Estrogen receptor modulators}}

[[Category:Antibiotics]]
[[Category:Antifungals]]
[[Category:Chloroarenes]]
[[Category:Endocrine disruptors]]
[[Category:Phenol ethers]]
[[Category:Steroid sulfotransferase inhibitors]]
[[Category:Xenoestrogens]]