Triclosan
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Triclosan (sometimes abbreviated as TCS) is an
antibacterial An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
and
antifungal An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as ...
agent present in some consumer products, including
toothpaste Toothpaste is a paste or gel dentifrice that is used with a toothbrush to clean and maintain the aesthetics of Human tooth, teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from th ...
,
soap Soap is a salt (chemistry), salt of a fatty acid (sometimes other carboxylic acids) used for cleaning and lubricating products as well as other applications. In a domestic setting, soaps, specifically "toilet soaps", are surfactants usually u ...
s,
detergent A detergent is a surfactant or a mixture of surfactants with Cleanliness, cleansing properties when in Concentration, dilute Solution (chemistry), solutions. There are a large variety of detergents. A common family is the alkylbenzene sulfonate ...
s, toys, and surgical cleaning treatments. It is similar in its uses and
mechanism of action In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical Drug interaction, interaction through which a Medication, drug substance produces its pharmacological effect. A mechanism of action usually includes mention o ...
to triclocarban. Its efficacy as an antimicrobial agent, the risk of
antimicrobial resistance Antimicrobial resistance (AMR or AR) occurs when microbes evolve mechanisms that protect them from antimicrobials, which are drugs used to treat infections. This resistance affects all classes of microbes, including bacteria (antibiotic resista ...
, and its possible role in disrupted hormonal development remains controversial. Additional research seeks to understand its potential effects on organisms and environmental health. Triclosan was developed in 1966. A 2006 study recommended showering with 2% triclosan as a regimen in surgical units to rid patients' skin of methicillin-resistant ''Staphylococcus aureus'' (MRSA).


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%), shampoos,
deodorant A deodorant is a substance applied to the body to prevent or mask body odor caused by bacterial breakdown of perspiration, for example in the armpits, groin, or feet. A subclass of deodorants, called antiperspirants, prevents sweating itself, t ...
s,
toothpaste Toothpaste is a paste or gel dentifrice that is used with a toothbrush to clean and maintain the aesthetics of Human tooth, teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from th ...
s, mouthwashes, cleaning supplies, and
pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...
s. It also was part of consumer products, including kitchen utensils, toys, bedding, socks, and trash bags. Triclosan was registered as a pesticide in 1969. U.S. EPA registration numbers are required for all EPA-registered pesticides. As of 2017, there were five registrations for triclosan with the EPA. Currently, there are 20 antimicrobial registrations with the EPA under the regulations of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). 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 Heating, ventilation, and air conditioning (HVAC ) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. ...
coils, where it prevents microbial growth that contributes to product degradation. In the United States, by 2000, triclosan and triclocarban (TCC) could be found in 75% of liquid soaps and 29% of bar soaps, and triclosan was used in more than 2,000 consumer products. In healthcare, triclosan is used in surgical scrubs and hand washes. Use in surgical units is effective with a minimum contact time of approximately two minutes. More recently, showering with 2% triclosan has become a recommended regimen in surgical units for the
decolonization Decolonization is the undoing of colonialism, the latter being the process whereby Imperialism, imperial nations establish and dominate foreign territories, often overseas. The meanings and applications of the term are disputed. Some scholar ...
of patients whose skin carries methicillin-resistant ''Staphylococcus aureus'' (MRSA). Two small uncontrolled case studies reported the use of triclosan correlated with reduction in MRSA infections. Triclosan is also used in the coatings for some surgical sutures. There is good evidence these triclosan-coated sutures reduce the risk of surgical site infection. 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. Triclosan has been employed as a selective agent in molecular cloning. A bacterial host transformed by a
plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria and ...
harboring a triclosan-resistant mutant ''FabI'' gene (mFabI) as a selectable marker can grow in presence of high dose of triclosan in growth media.


Effectiveness

In surgery, triclosan coated sutures reduce the risk of surgical site infection. Some studies suggest that antimicrobial hand soaps containing triclosan provide a slightly greater bacterial reduction on the hands compared to plain soap. , 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. A
Cochrane review Cochrane is a British international charitable organisation formed to synthesize medical research findings to facilitate evidence-based choices about health interventions involving health professionals, patients and policy makers. It includes ...
of 30 studies concluded that triclosan/copolymer-containing toothpastes produced a 22% reduction in both
dental plaque Dental plaque is a biofilm of microorganisms (mostly bacteria, but also fungi) that grows on surfaces within the mouth. It is a sticky colorless deposit at first, but when it forms Calculus (dental), tartar, it is often brown or pale yellow. It is ...
and gingival inflammation when compared with fluoride toothpastes without triclosan/copolymer. There was weak evidence of a reduction in tooth cavities, and no evidence of reduction in
periodontitis Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main c ...
. A study of triclosan toothpastes did not find any evidence that it causes an increase in serious adverse cardiac events such as heart attacks. A study by
Colgate-Palmolive The Colgate-Palmolive Company, commonly known as Colgate-Palmolive, is an American multinational corporation, multinational consumer products company headquartered on Park Avenue in Midtown Manhattan, New York City. The company specializes in ...
found a significant reduction in gingivitis, bleeding, and plaque with the use of triclosan-containing toothpaste. An independent review by the Cochrane group suggests that the reduction in gingivitis, bleeding, and plaque is statistically significant (unlikely to occur by chance) but not
clinically significant In medicine and psychology, clinical significance is the practical importance of a treatment effect—whether it has a real genuine, palpable, noticeable effect on daily life. Types of significance Statistical significance Statistical significanc ...
(unlikely to provide noticeable effects). Triclosan is used in food storage containers although this use is banned in the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
since 2010.
Veterinary Veterinary medicine is the branch of medicine that deals with the prevention, management, diagnosis, and treatment of disease, disorder, and injury in non-human animals. The scope of veterinary medicine is wide, covering all animal species, both ...
use as a biocidal product in the EU is governed by the Biocidal Products Directive.


Chemical structure and properties

This
organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
is a white powdered
solid Solid is a state of matter where molecules are closely packed and can not slide past each other. Solids resist compression, expansion, or external forces that would alter its shape, with the degree to which they are resisted dependent upon the ...
with a slight aromatic, phenolic odor. Categorized as a polychloro phenoxy phenol, triclosan is a chlorinated
aromatic compound Aromatic compounds or arenes are organic compounds "with a chemistry typified by benzene" and "cyclically conjugated." The word "aromatic" originates from the past grouping of molecules based on odor, before their general chemical properties were ...
that has
functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...
s representative of both
ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R†...
s and
phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...
s. Phenols often demonstrate antibacterial properties. Triclosan is soluble in
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
,
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...
,
diethyl ether Diethyl ether, or simply ether, is an organic compound with the chemical formula , sometimes abbreviated as . It is a colourless, highly Volatility (chemistry), volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It belongs ...
, and strongly
basic Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...
solutions such as a 1 M
sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...
solution, but only slightly soluble in water. 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 Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms a hexahydrate with the formula , containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are col ...
. The United States Pharmacopeia formulary has published a monograph for triclosan that sets purity standards.


Mechanism of action

At high concentrations, triclosan acts as a
biocide A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. The US Environmental Protection Agency (EPA) uses a sli ...
with multiple
cytoplasm The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...
ic and
membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. Bi ...
targets. However, at the lower concentrations seen in commercial products, triclosan appears
bacteriostatic A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily killing them otherwise. Depending on their application, bacteriostatic antibiotics, disinfec ...
, and it targets bacteria primarily by inhibiting
fatty acid synthesis In biochemistry, fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes. Two ''De novo synthesis, de novo'' fatty acid syntheses can be distinguished: cytosolic fatty acid synthesis (FAS/FASI) ...
. Triclosan binds to bacterial enoyl-acyl carrier protein reductase (ENR) enzyme,The WHO Guidelines on Hand Hygiene in Healthcare (Advanced Draft)
WHO, 2006, p. 37. "9.9 Triclosan"
which is encoded by the gene ''fabI''. This binding increases the enzyme's affinity for
nicotinamide adenine dinucleotide Nicotinamide adenine dinucleotide (NAD) is a Cofactor (biochemistry), coenzyme central to metabolism. Found in all living cell (biology), cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphat ...
(NAD+). This results in the formation of a stable, ternary complex of ENR-NAD+-triclosan, which is unable to participate in
fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
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.


Endocrine disruptor

Triclosan has been found to be a weak
endocrine disruptor Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine (or hormonal) systems. These disruptions can cause ...
, though the relevance of this to humans is uncertain. The compound has been found to bind with low
affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Pa ...
to both the
androgen receptor The androgen receptor (AR), also known as NR3C4 (nuclear receptor subfamily 3, group C, member 4), is a type of nuclear receptor that is activated by binding any of the androgenic hormones, including testosterone and dihydrotestosterone, in th ...
and the
estrogen receptor Estrogen receptors (ERs) are proteins found in cell (biology), cells that function as receptor (biochemistry), receptors for the hormone estrogen (17β-estradiol). There are two main classes of ERs. The first includes the intracellular estrogen ...
, where both
agonist An agonist is a chemical that activates a Receptor (biochemistry), receptor to produce a biological response. Receptors are Cell (biology), cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an R ...
ic and antagonistic responses have been observed.


Efflux pump inducer

Triclosan may upregulate or induce efflux pumps in bacteria causing them to become resistant against variety of other antibiotics.


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 Sewage sludge is the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term "septage" also refers to sludge from simple wastewater treatment but is connected to si ...
, or eating fish exposed to it. 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 The tomato (, ), ''Solanum lycopersicum'', is a plant whose fruit is an edible Berry (botany), berry that is eaten as a vegetable. The tomato is a member of the nightshade family that includes tobacco, potato, and chili peppers. It originate ...
and
onion An onion (''Allium cepa'' , from Latin ), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus '' Allium''. The shallot is a botanical variety of the onion which was classifie ...
plants. 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.


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.


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 The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...
, 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. Triclosan is thought to accumulate in wastewater and return to drinking water, thus propagating a buildup that could cause increasing effects with ongoing use. 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). (See
policy Policy is a deliberate system of guidelines to guide decisions and achieve rational outcomes. A policy is a statement of intent and is implemented as a procedure or protocol. Policies are generally adopted by a governance body within an or ...
section below).


Allergic

Triclosan has been associated with a higher risk of
food allergy A food allergy is an abnormal immune system, immune response to food. The symptoms of the allergic reaction may range from mild to severe. They may include pruritus, itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathi ...
. This may be because exposure to bacteria reduces
allergies Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allergy, food al ...
, as predicted by the hygiene hypothesis, and not caused by toxicology of triclosan itself. This effect may also occur with
chlorhexidine gluconate Chlorhexidine is a disinfectant and antiseptic which is used for skin disinfection before surgery and to disinfect surgical instruments. It is also used for cleaning wounds, preventing dental plaque, treating yeast infections of the mouth, ...
and chloroxylenol (PCMX), among other antibacterial agents. * Other studies have linked triclosan to allergic
contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes ...
in some individuals. Additionally, triclosan concentrations have been associated with allergic sensitization, especially inhalant and seasonal allergens, rather than food allergens.


By-product exposure

Triclosan can react with the free
chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...
in chlorinated tap water to produce lesser amounts of other compounds, such as 2,4-dichlorophenol. Some of these intermediates convert into dioxins upon exposure to UV radiation (from the sun or other sources). The dioxins that can form from triclosan are not thought to be congeners of toxicologic concern for mammals, birds and fish.


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. 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. 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 Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting se ...
levels in the infants.


History

Triclosan (TCS) was patented in 1964 by Swiss company Ciba-Geigy. The earliest known safety testing began in 1968. 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 Novartis AG is a Swiss multinational corporation, multinational pharmaceutical company, pharmaceutical corporation based in Basel, Switzerland. Novartis is one of the largest pharmaceutical companies in the world and was the eighth largest by re ...
. During the merger, Ciba-Geigy's chemical business was spun off to become
Ciba Specialty Chemicals Ciba was a chemical company based in and near Basel, Switzerland. "Ciba" stood for "Chemische Industrie Basel" (Chemical Industries Basel) and was formed when the non-pharmaceuticals elements of Novartis were spun out in 1997, following the merg ...
, which was acquired in 2008 by chemical giant
BASF BASF SE (), an initialism of its original name , is a European Multinational corporation, multinational company and the List of largest chemical producers, largest chemical producer in the world. Its headquarters are located in Ludwigshafen, Ge ...
. BASF currently manufactures TCS under the brand name Irgasan DP300.


Environmental concerns


Treatment and disposal

Exposure to triclosan in personal product use is relatively short. Upon disposal, triclosan is sent to municipal
sewage treatment Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water p ...
plants, where, in the United States, about 97–98% of triclosan is removed. 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. In a study on
effluent Effluent is wastewater from sewers or industrial outfalls that flows directly into surface waters, either untreated or after being treated at a facility. The term has slightly different meanings in certain contexts, and may contain various pol ...
from wastewater treatment facilities, approximately 75% of triclocarban was present in
sewage sludge Sewage sludge is the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term "septage" also refers to sludge from simple wastewater treatment but is connected to si ...
. 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 Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewerage, sewer system. Sewage consists of wastewater discharged fro ...
sludge after initial successful capture from wastewater is 44,000 ± 60,000 kg/yr. Triclosan can attach to other substances suspended in aquatic environments, which potentially endangers marine organisms and may lead to further bioaccumulation.
Ozone Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...
is considered to be an effective tool for removing triclosan during sewage treatment. As little triclosan is released through
plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...
and textile household consumer products, these are not considered to be major sources of triclosan contamination. During wastewater treatment, a portion of triclosan is degraded, while the remainder adsorbs to sewage sludge or exits the plant as effluent. 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. In the environment, triclosan may be degraded by microorganisms or react with sunlight, forming other compounds, which include chlorophenols and dioxins. During 1999 to 2000, US Geological Survey detected TCS in 57.6% of streams and rivers sampled.


Bioaccumulation

While studies using semi-permeable membrane devices have found that triclosan does not strongly bioaccumulate, methyl-triclosan is comparatively more stable and
lipophilic Lipophilicity (from Greek language, Greek λίπος "fat" and :wikt:φίλος, φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are c ...
and thus poses a higher risk of bioaccumulation. The ability of triclosan to bioaccumulate is affected by its ionization state in different environmental conditions.
Global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
may increase uptake and effects of triclosan in aquatic organisms.


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 Wastewater treatment is a process which removes and eliminates contaminants from wastewater. It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on ...
facilities that treat household wastewaters. Triclosan has been observed in multiple organisms, including algae, aquatic blackworms, fish, and
dolphin A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...
s. It has also been found in land animals including earthworms and species higher up the
food chain A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as ...
. In toxicity experiments with ''Vibrio fischeri'' marine bacterium, an EC50 value of TCS equal to 0.22 mg/L has been determined. 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. 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). 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.


Resistance concerns

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 ''Pseudomonas aeruginosa'' is a common Bacterial capsule, encapsulated, Gram-negative bacteria, Gram-negative, Aerobic organism, aerobic–facultative anaerobe, facultatively anaerobic, Bacillus (shape), rod-shaped bacteria, bacterium that can c ...
'' and '' Stenotrophomonas maltophilia'', already resistant to triclosan, had increased resistance against antibiotics tetracycline and norfloxacin when exposed to triclosan. 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 ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often posi ...
'' and ''
Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...
''. This was not observed with exposure to
chlorhexidine Chlorhexidine is a disinfectant and antiseptic which is used for skin disinfection before surgery and to disinfect surgical instruments. It is also used for cleaning wounds, preventing dental plaque, treating yeast infections of the mouth, and ...
or a hydrogen
peroxide In chemistry, peroxides are a group of Chemical compound, compounds with the structure , where the R's represent a radical (a portion of a complete molecule; not necessarily a free radical) and O's are single oxygen atoms. Oxygen atoms are joined ...
-based agent (during the conditions in said study).


Alternatives

A comprehensive
meta-analysis Meta-analysis is a method of synthesis of quantitative data from multiple independent studies addressing a common research question. An important part of this method involves computing a combined effect size across all of the studies. As such, th ...
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.". Nonorganic antibiotics and organic biocides are effective alternatives to triclosan, such as silver and copper ions and
nanoparticle A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At ...
s.


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. 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." The proposed rule lists dozens of products that were already on the market at the time and the firms that produced them. 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." 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. 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." In the 1994 update to the rule, TCS was effectively removed from the drug category which made it available for use in consumer products. In 2010, the
Natural Resources Defense Council The Natural Resources Defense Council (NRDC) is a United States–based 501(c)(3) non-profit international environmental advocacy group, with its headquarters in New York City and offices in Washington, D.C., San Francisco, Los Angeles, Chicag ...
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. On December 17, 2013, the FDA issued a draft rule revoking the
generally recognized as safe Generally recognized as safe (GRAS) is a United States Food and Drug Administration (FDA) designation that a chemical or substance added to food is considered safe by experts under the conditions of its intended use. An ingredient with a GRAS d ...
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. 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. 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 Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...
(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) * 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." 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); 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. 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. 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. Triclosan was not approved by the European Commission as an active substance for use in biocidal products for product-type 1 in January 2016. 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. Use of triclosan in cosmetic products was restricted by the EU commission in 2014.Commission Regulation (EU) No 358/2014 of 9 April 2014


See also


References

{{Estrogen receptor modulators Antibiotics Antifungals Chloroarenes Endocrine disruptors Phenol ethers Steroid sulfotransferase inhibitors Xenoestrogens