Triclosan
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Triclosan.PNG
Triclosan (chemically 5-chloro-2-(2,4-dichlorophenoxy)phenol) is a potent wide-spectrum antibacterial and antifungal agent.
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Chemistry
This organic chemical compound is a white powdered solid (at room temperature and pressure) with a melting point of about 55-57°C and a slight aromatic/phenolic odor. It is a chlorinated aromatic compound which has functional groups representative of both ethers and phenols. Phenols often show anti-bacterial properties. The chemical formula is C12H7Cl3O2 and the molecular mass is 289.5 g/mole. Triclosan is slightly soluble in water, but soluble in ethanol, diethyl ether, and stronger basic solutions such as 1 M NaOH, like many other phenols. The CAS number is 3380-34-5. Although the IUPAC name is 5-chloro-2-(2,4-dichlorophenoxy)-phenol, the chemical names 2,4,4'-Trichloro-2'-hydroxydiphenyl ether and 2,4,4'-Trichloro-2'-hydroxydiphenyl oxide are also used for triclosan.
Uses
It is found in soaps, deodorants, toothpastes and is impregnated in an increasing number of consumer products, such as kitchen utensils, toys, bedding, socks, and trash bags. It has been shown to be effective in reducing and controlling bacterial contamination on the hands and on treated products.
Triclosan is highly regulated by both the U.S. Food and Drug Administration and by the European Union. In the environment, triclosan is removed during normal waste treatment processes as shown by extensive environmental studies, and any that remains after waste treatment quickly breaks down in the environment.
Resistance concerns
An article coauthored by Dr. Stuart Levy in the August 6, 1998 issue of Nature warned that its overuse could cause resistant strains of bacteria to develop, in much the same way that antibiotic-resistant bacterial strains are emerging, based on speculation that triclosan behaved like an antibiotic. Based on this speculation, in 2003, the Sunday Herald newspaper reported (http://ww1.sundayherald.com/37782) 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 biocides like triclosan, based on work by Dr. Peter Gilbert in the UK. At least seven peer-reviewed and published studies have been conducted demonstrating that triclosan does not cause bacterial resistance, including one study coauthored by Dr. Levy, published in August of 2004 in Antimicrobial Agents and Chemotherapy. In addition, there is 30 years of experience with triclosan without a single incidence of acquired bacterial resistance reported, and there are no studies showing acquired resistance after long-term use.
Other concerns
Studies have shown that triclosan can combine with chlorine in tap water to form chloroform gas. The U.S. EPA classifies chloroform as a probable human carcinogen. Triclosan was recently the target of a UK cancer alert and is used in many common household products including Dentyl mouthwash, Colgate Total fresh stripe, Colgate Total, Sensodyne Total Care, Mentadent, and Aquafresh.
see also: dioxin
External links
- Antibacterials? Here's the Rub (http://www.worldwatch.org/pubs/goodstuff/soap/)
- Picture of structure (http://pubchem.ncbi.nlm.nih.gov/image/imgsrv.fcgi?t=l&cid=5564)
- Toothpaste cancer alert (http://www.thisislondon.co.uk/news/articles/17956139?source=Evening%20Standard&ct=5)
- When chlorine + antimicrobials = unintended consequences (http://pubs.acs.org/subscribe/journals/esthag-w/2005/apr/science/kb_chlorine.html)