Triclosan
Encyclopedia
Triclosan is an antibacterial
and antifungal
agent. It is a polychloro phenoxy phenol
. Despite being used in many consumer products, beyond its use in toothpaste to prevent gingivitis, there is no evidence according to the American Food and Drug Administration
(FDA) that triclosan provides an extra benefit to health in other consumer products. Triclosan safety is currently under review by the FDA and Health Canada.
is a white powdered solid
with a slight aromatic/phenolic odor. It is a chlorinated
aromatic compound
that has functional group
s representative of both ether
s and phenol
s. Phenols often show antibacterial properties. Triclosan is only slightly soluble in water, but soluble in ethanol
, methanol
, diethyl ether
, and strong basic solution
s such as 1 M sodium hydroxide. Triclosan can be synthesized from 2,4-dichlorophenol
.
Some common impurities are: 2,4-dichlorophenol, 3-chlorophenol, 4-chlorophenol, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzo-p-furan, 2,8-dichlorobenzo-furan, 2,8-dichlorobenzo-p-dioxin, 1,3,7-trichlorodibenzo-p-dioxin and 2,4,8-trichlorodibenzo-furan
in benzene under reflux.
Triclosan can be synthesized through a three-step process starting with 1-(2-hydroxyethyl)pyrrolidin-2-one. The 1-(2-hydroxyethyl)pyrrolidin-2-one is to be dehydrated with either zinc or calcium oxide into 1-vinylpyrrolidin-2-one. Then, 1-vinylpyrrolidin-2-one can be reacted with 5-chloro-2-(2,4-dichlorophenoxy)phenyl acrylate in n-heptane to form triclosan.
s, toothpaste
s, shaving cream
s, mouth washes, and cleaning supplies, and is infused in an increasing number of consumer products, such as kitchen utensils, toys, bedding, socks, and trash bags. Triclosan has been shown to be effective in reducing and controlling bacteria
l contamination on the hands and on treated products. More recently, showering or bathing with 2% triclosan has become a recommended regimen for the decolonization of patients whose skin is carrying methicillin-resistant Staphylococcus aureus
(MRSA) following the successful control of MRSA outbreaks in several clinical settings.
Triclosan is regulated by the U.S. Food and Drug Administration
, the Environmental Protection Agency, and the European Union
. During wastewater
treatment, a portion of triclosan is degraded, while the remaining adsorbs to sewage sludge
or exits the plant in wastewater effluent. In the environment, triclosan may be degraded by microorganisms or react with sunlight, forming other compounds, which include between 3 and 12 % of chlorophenols and dioxin (In particular, 2,8-dichlorodibenzo-p-dioxin (external) (2,8-DCDD) and 2,4-dichlorophenol
(2,4-DCP) are produced. Both also are photolabile and, thus, are intermediates.), or it may adsorb to particles that settle out of the water column and form sediment. Triclosan was found in Greifensee
sediment that was over 30 years old, suggesting that triclosan is degraded or removed slowly in sediment.
The use of triclosan as an additive for plastic production for use in food packages has not been approved by the EC.
, with multiple cytoplasmic and membrane targets. At lower concentrations, however, triclosan appears bacteriostatic and is seen to target bacteria mainly by inhibiting fatty acid synthesis. Triclosan binds to bacterial enoyl-acyl carrier protein reductase
enzyme (ENR), which is encoded by the gene FabI. This binding increases the enzyme's affinity for nicotinamide adenine dinucleotide
(NAD+). This results in the formation of a stable ternary complex of ENR-NAD+-triclosan, which is unable to participate in fatty acid synthesis. Fatty acids are necessary for reproducing and building cell membranes. Humans do not have an ENR enzyme, and thus are not affected.
Some bacterial species can develop low-level resistance to triclosan at its lower bacteriostatic concentrations due to FabI mutations, which results in a decrease of triclosan's effect on ENR-NAD+ binding, as shown in Escherichia coli
and Staphylococcus aureus
. Another way for these bacteria to gain low-level resistance to triclosan is to overexpress FabI. Some bacteria have innate resistance to triclosan at low, bacteriostatic levels, such as Pseudomonas aeruginosa
, which possesses multi-drug efflux pumps that "pump" triclosan out of the cell. Other bacteria, such as some of the Bacillus
genus, have alternative FabI genes (FabK) to which triclosan does not bind and hence are less susceptible.
warned that triclosan's overuse could cause resistant strains of bacteria
to develop, in much the same way that antibiotic-resistant
bacterial strains are emerging. In 2003, the Scottish Sunday Herald
newspaper reported that some UK supermarkets and other retailers were considering phasing out products containing triclosan.
It has since been shown that the laboratory method used by Dr. Levy was not effective in predicting bacterial resistance for biocide
s like triclosan. At least seven peer-reviewed and published studies have been conducted demonstrating that triclosan is not significantly associated with bacterial resistance over the short term, including one study coauthored by Dr. Levy.
Some level of triclosan resistance can occur in some microorganisms, but the larger concern is with the potential for cross-resistance or co-resistance to other antimicrobials. Studies investigating this possibility have been limited.
The European Commission Scientific Committee on Consumer Safety (SCCS) concludes that to date, there is no evidence that using triclosan leads to an increase in antibiotic resistance. However it is too early to say that triclosan exposure never leads to microbial resistance, as there is not yet enough information to make a full risk analysis.
and not toxicology of the triclosan itself and would thus occur with Chlorhexidine gluconate
and PCMX, amongst other antibacterial agents. Other studies have linked triclosan to allergic contact dermatitis in some individuals.
asked the Canadian government to ban triclosan use in household products under concerns of creating bacterial resistance and producing dangerous side products (chloroform).
Triclosan also reacts with the free chlorine in tap water to produce lesser amounts of other compounds, like 2,4-dichlorophenol
. Most of these intermediates convert into dioxins upon exposure to UV radiation (from the sun or other sources). Although small amounts of dioxins are produced, there is a great deal of concern over this effect, because some dioxins are extremely toxic and are very potent endocrine disruptor
s. They are also chemically very stable, so that they are eliminated from the body very slowly (they can bioaccumulate to dangerous levels), and they persist in the environment for a very long time.
Triclosan is chemically somewhat similar to the dioxin class of compounds. Its production leads to small amounts of residual polychlorinated dioxins, and polychlorinated furan
s, which are contained in small amounts, in the products that are using it.
The American Dental Association
published a response to the concerns stemming from the Virginia Tech study stating that the study is not relevant to toothpaste.
algae which are responsible for a large part of the photosynthesis
on Earth.
in the North American bullfrog
. The hypothesis proposed is that triclosan blocks the metabolism of thyroid hormone because it chemically mimics thyroid hormone and binds to the hormone receptor sites, blocking them, so that normal hormones cannot be used. A study between 2003 and 2006 concluded that triclosan (as an endocrine disruptor) affects the immune system and showed a positive association with allergy or hay fever diagnosis. Another study in 2000 offered the result that low amount of triclosan can be absorbed through skin and can enter the bloodstream.
Triclosan has also been found in both the bile of fish living downstream from waste-water-processing plants and in human milk. The negative effects of triclosan on the environment and its questionable benefits in toothpastes have led to the Swedish Naturskyddsföreningen to recommend not using triclosan in toothpaste. Another 2009 study demonstrated that triclosan exposure significantly impacts thyroid hormone concentrations in the male juvenile rats.
Triclosan is also showing up in dolphins near South Carolina and Florida in concentrations known to disrupt hormones, growth, and development in other animals.
in tap water to form chloroform
, which the United States Environmental Protection Agency
classifies as a probable human carcinogen
, meaning it could cause cancer
. These recent reports show that triclosan reacts with the free chlorine in tap water to further substitute triclosan with chlorine atoms. These intermediates can be cleaved to form chlorophenols that can react with free chlorine to form trihalomethanes, such as chloroform. As a result, triclosan was the target of a UK cancer alert, even though the study showed that the amount of chloroform generated was less than amounts often present in chlorinated drinking waters.
Nonorganic antibiotics and organic biocides are effective alternatives to triclosan, such as silver and copper ions and nanoparticle
s.
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
and antifungal
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
agent. It is a polychloro phenoxy phenol
Polychloro phenoxy phenol
Polychloro phenoxy phenols are a group of organic polyhalogenated compounds. Among them include triclosan and predioxin, the former which can have trace amounts of dioxins and furans, and the latter which degrades to produce dioxins...
. Despite being used in many consumer products, beyond its use in toothpaste to prevent gingivitis, there is no evidence according to the American Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(FDA) that triclosan provides an extra benefit to health in other consumer products. Triclosan safety is currently under review by the FDA and Health Canada.
Chemical structure and properties
This organic compoundOrganic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
is a white powdered solid
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
with a slight aromatic/phenolic odor. It is a chlorinated
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
aromatic compound
Simple aromatic ring
Simple aromatic rings, also known as simple arenes or simple aromatics, are aromatic organic compounds that consist only of a conjugated planar ring system with delocalized pi electron clouds. Many simple aromatic rings have trivial names. They are usually found as substructures of more complex...
that has functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
s representative of both ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
s and phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...
s. Phenols often show antibacterial properties. Triclosan is only slightly soluble in water, but soluble in ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
, methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
, diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
, and strong basic solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
s such as 1 M sodium hydroxide. Triclosan can be synthesized from 2,4-dichlorophenol
2,4-Dichlorophenol
2,4-Dichlorophenol is a chlorinated derivative of phenol with the molecular formula C6H4Cl2O. 2,4-DCP is used primarily as an intermediate in the preparation of the herbicide 2,4-dichlorophenoxyacetic acid . Annual worldwide production is estimated at 88 million pounds...
.
Some common impurities are: 2,4-dichlorophenol, 3-chlorophenol, 4-chlorophenol, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzo-p-furan, 2,8-dichlorobenzo-furan, 2,8-dichlorobenzo-p-dioxin, 1,3,7-trichlorodibenzo-p-dioxin and 2,4,8-trichlorodibenzo-furan
Synthesis
2,4,4'-trichloro-2'-methoxydiphenyl ether is treated with aluminium chlorideAluminium chloride
Aluminium chloride is the main compound of aluminium and chlorine. It is white, but samples are often contaminated with iron trichloride, giving it a yellow colour. The solid has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large...
in benzene under reflux.
Triclosan can be synthesized through a three-step process starting with 1-(2-hydroxyethyl)pyrrolidin-2-one. The 1-(2-hydroxyethyl)pyrrolidin-2-one is to be dehydrated with either zinc or calcium oxide into 1-vinylpyrrolidin-2-one. Then, 1-vinylpyrrolidin-2-one can be reacted with 5-chloro-2-(2,4-dichlorophenoxy)phenyl acrylate in n-heptane to form triclosan.
Reactions
It can be used to produce 2-(2,4-dichloro-phenoxy)-4,5-dichloro-phenol at 20 °C with the reagent sulfuryl chlorideSulfuryl chloride
Sulfuryl chloride is an inorganic compound with the formula SO2Cl2. At room temperature, it is a colorless liquid with a pungent odor. Sulfuryl chloride is not found in nature, as can be inferred from its rapid hydrolysis....
Uses
Triclosan has been used since 1972, and it is present in soaps (0.10-1.00%), deodorantDeodorant
Deodorants are substances applied to the body to affect body odor caused by bacterial growth and the smell associated with bacterial breakdown of perspiration in armpits, feet and other areas of the body. A subgroup of deodorants, antiperspirants, affect odor as well as prevent sweating by...
s, toothpaste
Toothpaste
Toothpaste is a paste or gel dentifrice used with a toothbrush as an accessory to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it serves as an abrasive that aids in removing the dental plaque and food from the teeth, assists in suppressing...
s, shaving cream
Shaving cream
Shaving cream is a substance that is applied to the face or wherever else hair grows, to provide lubrication and avoid razor burn during shaving. Shaving cream is often bought in a spray can, but can also be purchased in tubs or tubes. Shaving cream in a can is commonly dispensed as a foam or a gel...
s, mouth washes, and cleaning supplies, and is infused in an increasing number of consumer products, such as kitchen utensils, toys, bedding, socks, and trash bags. Triclosan has been shown to be effective in reducing and controlling bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
l contamination on the hands and on treated products. More recently, showering or bathing with 2% triclosan has become a recommended regimen for the decolonization of patients whose skin is carrying methicillin-resistant Staphylococcus aureus
Methicillin-resistant Staphylococcus aureus
Methicillin-resistant Staphylococcus aureus is a bacterium responsible for several difficult-to-treat infections in humans. It is also called multidrug-resistant Staphylococcus aureus and oxacillin-resistant Staphylococcus aureus...
(MRSA) following the successful control of MRSA outbreaks in several clinical settings.
Triclosan is regulated by the U.S. Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
, the Environmental Protection Agency, and the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
. During wastewater
Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...
treatment, a portion of triclosan is degraded, while the remaining adsorbs to sewage sludge
Sludge
Sludge refers to the residual, semi-solid material left from industrial wastewater, or sewage treatment processes. It can also refer to the settled suspension obtained from conventional drinking water treatment, and numerous other industrial processes...
or exits the plant in wastewater effluent. In the environment, triclosan may be degraded by microorganisms or react with sunlight, forming other compounds, which include between 3 and 12 % of chlorophenols and dioxin (In particular, 2,8-dichlorodibenzo-p-dioxin (external) (2,8-DCDD) and 2,4-dichlorophenol
2,4-Dichlorophenol
2,4-Dichlorophenol is a chlorinated derivative of phenol with the molecular formula C6H4Cl2O. 2,4-DCP is used primarily as an intermediate in the preparation of the herbicide 2,4-dichlorophenoxyacetic acid . Annual worldwide production is estimated at 88 million pounds...
(2,4-DCP) are produced. Both also are photolabile and, thus, are intermediates.), or it may adsorb to particles that settle out of the water column and form sediment. Triclosan was found in Greifensee
Greifensee
Greifensee is a small lake in the canton of Zürich in Switzerland.- Geography :Lake Greifen is located to the northeast of the city of Zurich, separated by the Pfannenstiel from Lake Zürich...
sediment that was over 30 years old, suggesting that triclosan is degraded or removed slowly in sediment.
The use of triclosan as an additive for plastic production for use in food packages has not been approved by the EC.
Mechanism of action
At in-use concentrations, triclosan acts as a biocideBiocide
A biocide is a chemical substance or microorganism which can deter, render harmless, or exert a controlling effect on any harmful organism by chemical or biological means. Biocides are commonly used in medicine, agriculture, forestry, and industry...
, with multiple cytoplasmic and membrane targets. At lower concentrations, however, triclosan appears bacteriostatic and is seen to target bacteria mainly by inhibiting fatty acid synthesis. Triclosan binds to bacterial enoyl-acyl carrier protein reductase
Enoyl-acyl carrier protein reductase
Enoyl-acyl carrier protein reductase , is a key enzyme of the type II fatty acid synthesis system. ENR is an attractive target for narrow-spectrum antibacterial drug discovery because of its essential role in metabolism and its sequence conservation across many bacterial species...
enzyme (ENR), which is encoded by the gene FabI. This binding increases the enzyme's affinity for nicotinamide adenine dinucleotide
Nicotinamide adenine dinucleotide
Nicotinamide adenine dinucleotide, abbreviated NAD, is a coenzyme found in all living cells. The compound is a dinucleotide, since it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine base and the other nicotinamide.In metabolism, NAD is involved...
(NAD+). This results in the formation of a stable ternary complex of ENR-NAD+-triclosan, which is unable to participate in fatty acid synthesis. Fatty acids are necessary for reproducing and building cell membranes. Humans do not have an ENR enzyme, and thus are not affected.
Some bacterial species can develop low-level resistance to triclosan at its lower bacteriostatic concentrations due to FabI mutations, which results in a decrease of triclosan's effect on ENR-NAD+ binding, as shown in Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
and Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
. Another way for these bacteria to gain low-level resistance to triclosan is to overexpress FabI. Some bacteria have innate resistance to triclosan at low, bacteriostatic levels, such as Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...
, which possesses multi-drug efflux pumps that "pump" triclosan out of the cell. Other bacteria, such as some of the Bacillus
Bacillus
Bacillus is a genus of Gram-positive, rod-shaped bacteria and a member of the division Firmicutes. Bacillus species can be obligate aerobes or facultative anaerobes, and test positive for the enzyme catalase. Ubiquitous in nature, Bacillus includes both free-living and pathogenic species...
genus, have alternative FabI genes (FabK) to which triclosan does not bind and hence are less susceptible.
Formation of dioxin in surface water
The use of triclosan in household antibacterial products introduces the chemical to surface waters where it can form dioxins. The dioxin-like compounds that formed when triclosan degraded in sunlight and wastewater chlorine treatment were analyzed in sediment cores by University of Minnesota researchers.Resistance concerns
An article coauthored by Dr. Stuart Levy in the August 6, 1998 issue of NatureNature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
warned that triclosan's overuse could cause resistant strains of bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
to develop, in much the same way that antibiotic-resistant
Antibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...
bacterial strains are emerging. In 2003, the Scottish Sunday Herald
Sunday Herald
The Sunday Herald is a Scottish Sunday newspaper launched on 7 February 1999. The ABC audited circulation in April 2011 showed sales of 31,123.From the start it has combined a centre-left stance with support for Scottish devolution...
newspaper reported that some UK supermarkets and other retailers were considering phasing out products containing triclosan.
It has since been shown that the laboratory method used by Dr. Levy was not effective in predicting bacterial resistance for biocide
Biocide
A biocide is a chemical substance or microorganism which can deter, render harmless, or exert a controlling effect on any harmful organism by chemical or biological means. Biocides are commonly used in medicine, agriculture, forestry, and industry...
s like triclosan. At least seven peer-reviewed and published studies have been conducted demonstrating that triclosan is not significantly associated with bacterial resistance over the short term, including one study coauthored by Dr. Levy.
Some level of triclosan resistance can occur in some microorganisms, but the larger concern is with the potential for cross-resistance or co-resistance to other antimicrobials. Studies investigating this possibility have been limited.
The European Commission Scientific Committee on Consumer Safety (SCCS) concludes that to date, there is no evidence that using triclosan leads to an increase in antibiotic resistance. However it is too early to say that triclosan exposure never leads to microbial resistance, as there is not yet enough information to make a full risk analysis.
Health concerns
Triclosan is used in a variety of common household products, including soaps, mouthwashes, dish detergents, toothpastes, deodorants, and hand sanitizers. In the United States, manufacturers of products containing triclosan must indicate it on the label.Allergy
A 2010 study linked triclosan usage in children with the development of allergies, suggesting that children with higher exposure to triclosan are more frequently diagnosed with allergies as related to the Hygiene TheoryHygiene hypothesis
In medicine, the Hygiene Hypothesis states that a lack of early childhood exposure to infectious agents, symbiotic microorganisms , and parasites increases susceptibility to allergic diseases by suppressing natural development of the immune system...
and not toxicology of the triclosan itself and would thus occur with Chlorhexidine gluconate
Chlorhexidine gluconate
Chlorhexidine is a chemical antiseptic. It is effective on both Gram-positive and Gram-negative bacteria, although it is less effective with some Gram-negative bacteria. It has both bactericidal and bacteriostatic mechanisms of action, the mechanism of action being membrane disruption, not ATPase...
and PCMX, amongst other antibacterial agents. Other studies have linked triclosan to allergic contact dermatitis in some individuals.
By-products
In August 2009, the Canadian Medical AssociationCanadian Medical Association
The Canadian Medical Association , with more than 70,000 members, is the largest association of doctors in Canada and works to represent their interests nationally. It formed in 1867, three months after Confederation...
asked the Canadian government to ban triclosan use in household products under concerns of creating bacterial resistance and producing dangerous side products (chloroform).
Triclosan also reacts with the free chlorine in tap water to produce lesser amounts of other compounds, like 2,4-dichlorophenol
2,4-Dichlorophenol
2,4-Dichlorophenol is a chlorinated derivative of phenol with the molecular formula C6H4Cl2O. 2,4-DCP is used primarily as an intermediate in the preparation of the herbicide 2,4-dichlorophenoxyacetic acid . Annual worldwide production is estimated at 88 million pounds...
. Most of these intermediates convert into dioxins upon exposure to UV radiation (from the sun or other sources). Although small amounts of dioxins are produced, there is a great deal of concern over this effect, because some dioxins are extremely toxic and are very potent endocrine disruptor
Endocrine disruptor
Endocrine disruptors are chemicals that interfere with endocrine in animals, including humans. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders...
s. They are also chemically very stable, so that they are eliminated from the body very slowly (they can bioaccumulate to dangerous levels), and they persist in the environment for a very long time.
Triclosan is chemically somewhat similar to the dioxin class of compounds. Its production leads to small amounts of residual polychlorinated dioxins, and polychlorinated furan
Furan
Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen. The class of compounds containing such rings are also referred to as furans....
s, which are contained in small amounts, in the products that are using it.
The American Dental Association
American Dental Association
The American Dental Association is an American professional association established in 1859 which has more than 155,000 members. Based in Chicago, the ADA is the world's largest and oldest national dental association and promotes good oral health to the public while representing the dental...
published a response to the concerns stemming from the Virginia Tech study stating that the study is not relevant to toothpaste.
Environment
Triclosan is toxic to aquatic bacteria at levels found in the environment. Triclosan inhibits photosynthesis in diatomDiatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
algae which are responsible for a large part of the photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
on Earth.
Endocrine disruption
A 2006 study concluded that low doses of triclosan act as an endocrine disruptorEndocrine disruptor
Endocrine disruptors are chemicals that interfere with endocrine in animals, including humans. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders...
in the North American bullfrog
Bullfrog
The American bullfrog , often simply known as the bullfrog in Canada and the United States, is an aquatic frog, a member of the family Ranidae, or “true frogs”, native to much of North America. This is a frog of larger, permanent water bodies, swamps, ponds, and lakes, where it is usually found...
. The hypothesis proposed is that triclosan blocks the metabolism of thyroid hormone because it chemically mimics thyroid hormone and binds to the hormone receptor sites, blocking them, so that normal hormones cannot be used. A study between 2003 and 2006 concluded that triclosan (as an endocrine disruptor) affects the immune system and showed a positive association with allergy or hay fever diagnosis. Another study in 2000 offered the result that low amount of triclosan can be absorbed through skin and can enter the bloodstream.
Triclosan has also been found in both the bile of fish living downstream from waste-water-processing plants and in human milk. The negative effects of triclosan on the environment and its questionable benefits in toothpastes have led to the Swedish Naturskyddsföreningen to recommend not using triclosan in toothpaste. Another 2009 study demonstrated that triclosan exposure significantly impacts thyroid hormone concentrations in the male juvenile rats.
Triclosan is also showing up in dolphins near South Carolina and Florida in concentrations known to disrupt hormones, growth, and development in other animals.
Probable Carcinogen
Reports have suggested that triclosan can combine with chlorineChlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
in tap water to form chloroform
Chloroform
Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous...
, which the United States Environmental Protection Agency
United States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
classifies as a probable human carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
, meaning it could cause cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
. These recent reports show that triclosan reacts with the free chlorine in tap water to further substitute triclosan with chlorine atoms. These intermediates can be cleaved to form chlorophenols that can react with free chlorine to form trihalomethanes, such as chloroform. As a result, triclosan was the target of a UK cancer alert, even though the study showed that the amount of chloroform generated was less than amounts often present in chlorinated drinking waters.
Alternatives
A comprehensive analysis from the University of Michigan School of Public Health indicated that plain soaps are just as effective as consumer-grade antibacterial soaps with triclosan in preventing illness and removing bacteria from the hands.Nonorganic antibiotics and organic biocides are effective alternatives to triclosan, such as silver and copper ions and nanoparticle
Nanoparticle
In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties. Particles are further classified according to size : in terms of diameter, coarse particles cover a range between 10,000 and 2,500 nanometers. Fine particles are sized...
s.
See also
- Chlorhexidine gluconateChlorhexidine gluconateChlorhexidine is a chemical antiseptic. It is effective on both Gram-positive and Gram-negative bacteria, although it is less effective with some Gram-negative bacteria. It has both bactericidal and bacteriostatic mechanisms of action, the mechanism of action being membrane disruption, not ATPase...
- ChlorineChlorineChlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
- ChloroformChloroformChloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous...
- ChloroxylenolChloroxylenolChloroxylenol is an antimicrobial chemical compound used to control bacteria, algae, and fungi in adhesives, emulsions, paints, and wash tanks. It is also commonly used in antibacterial soaps such as Dettol and ointments, such as the now discontinued Medicated Vaseline. Studies have shown a low...
- Dioxin
- FuranFuranFuran is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen. The class of compounds containing such rings are also referred to as furans....
- Hygiene hypothesisHygiene hypothesisIn medicine, the Hygiene Hypothesis states that a lack of early childhood exposure to infectious agents, symbiotic microorganisms , and parasites increases susceptibility to allergic diseases by suppressing natural development of the immune system...
- TriclocarbanTriclocarbanTriclocarban , or 3,4,4'-trichlorocarbanilide, is a substance with anti-bacterial and anti-fungal properties that is used in disinfectants, soaps and other household products....
- ToothpasteToothpasteToothpaste is a paste or gel dentifrice used with a toothbrush as an accessory to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it serves as an abrasive that aids in removing the dental plaque and food from the teeth, assists in suppressing...
External links
- Triclosan and Its Impurities
- Antibacterials? Here's the Rub – campaign site.
- Antibacterial Chemical Raises Safety Issues New York Times Aug 19, 2011