Triclosan (sometimes abbreviated as TCS) is an antibacterial and antifungal agent present in some consumer products, including toothpaste, soaps, detergents, toys, and surgical cleaning treatments.

[1] A 2006 study recommended showering with 2% triclosan as a regimen in surgical units to rid patients' skin of methicillin-resistant Staphylococcus aureus (MRSA).

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%), shampoos, deodorants, toothpastes, mouthwashes, cleaning supplies, and pesticides.

[5] 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.

Triclosan may be directly applied to commercial HVAC coils, where it prevents microbial growth that contributes to product degradation.

[11][12] More recently, showering with 2% triclosan has become a recommended regimen in surgical units for the decolonization of patients whose skin carries methicillin-resistant Staphylococcus aureus (MRSA).

A bacterial host 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.

[22] A study of triclosan toothpastes did not find any evidence that it causes an increase in serious adverse cardiac events such as heart attacks.

[32] However, at the lower concentrations seen in commercial products, triclosan appears bacteriostatic, and it targets bacteria primarily by inhibiting fatty acid synthesis.

[citation needed] Triclosan binds to bacterial enoyl-acyl carrier protein reductase (ENR) enzyme,[33] which is encoded by the gene fabI.

[36][37] 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.

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.

[41] Triclosan is thought to accumulate in wastewater and return to drinking water, thus propagating a buildup that could cause increasing effects with ongoing use.

[42] 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).

[51][52] Concerns on the health effects of triclosan have been raised after it was detected in human breast milk, blood, and urine samples.

In a 2017 study on 537 pregnant women in China, prenatal triclosan exposure was associated with increased cord testosterone levels in the infants.

[9] Studies show that substantial quantities of triclosan (170,000–970,000 kg/yr) can escape from wastewater treatment plants and damage algae on surface waters.

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 kg/yr.

[9] Triclosan can attach to other substances suspended in aquatic environments, which potentially endangers marine organisms and may lead to further bioaccumulation.

[59] During wastewater treatment, a portion of triclosan is degraded, while the remainder adsorbs to sewage sludge or exits the plant as effluent.

[70] 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.

[citation needed] In 1974, the US FDA began the drug review monograph process for "over-the-counter (OTC) topical antimicrobial products", including triclosan and triclocarban.

"[75] 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] 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 also requesting data and information concerning the safety and effectiveness of topical antimicrobials for use as hand sanitizers or dips.

[77] 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.

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.

[82] 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.

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.