Triclosan

OVERVIEW

Triclosan (TRY-klo-san) is a white crystalline powder with antimicrobial properties that make it a useful ingredient in soaps, cosmetics, acne medications, deodorants, foot sprays and foot powders, toothpastes, and mouthwashes. It acts as an antimicrobial by inhibiting the action of an enzyme called enoyl-acyl carrier-protein reductase (ENR) that bacteria and fungi need to survive. The enzyme is used in the synthesis of fatty acids from which cell membranes are constructed. Having lost the ability to manufacture cell walls, bacteria and fungi die. The ENR enzyme is not present in humans, so triclosan has no effect on the human body.

Triclosan is also known by the following names: 5-chloro-2-(2,4-dichlorophenoxy)phenol; trichloro-2'-hydroxydiphenylether; and 2,4,4'-trichloro-2'-hydroxydiphenyl ether.

KEY FACTS

OTHER NAMES:

See Overview

FORMULA:

C₆H₃ClOH-O-C₆H₃Cl₂

ELEMENTS:

Carbon, hydrogen, oxygen, chlorine

COMPOUND TYPE:

Organic

STATE:

Solid

MOLECULAR WEIGHT:

289.54 g/mol

MELTING POINT:

55°C to 57°C (131°F to 135°F)

BOILING POINT:

Not applicable

SOLUBILITY:

Slightly soluble in water; soluble in many organic solvents

HOW IT IS MADE

Two procedures are available for the synthesis of triclosan. In one, 1,4-dichloro-2-nitrobenzene (C₆H₃Cl₂NO₃) is reacted with 2,4-dichlorophenol (C₆H₃ClOH) to obtain triclosan. In the second procedure, 2,4-dichlorobenzene (C₆H₄Cl₂), acetyl chloride (CH₃OCl), and 2,4-dichlorophenol (C₆H₃ClOH) are reacted with each other to obtain the product.

COMMON USES AND POTENTIAL HAZARDS

Triclosan has been used in soaps and other cleaning products since the 1960s. Hospitals found the compound to be very effective in controlling bacteria on hands and surfaces. Medical staff used it to stop outbreaks of infections caused by common bacteria such as Staphylococcus aureus. The compound is still used widely in hospitals for this purpose. In the 1990s, triclosan began to appear in a much wider array of products including antibacterial soaps, body washes, toothpastes, and dishwashing liquids. By the early 2000s, it was also being used in toothbrushes, plastic toys, and socks. The addition of triclosan to tooth care products is based on evidence that the compound may inhibit the growth of bacteria that cause dental caries (cavities). The compound has also proved to be effective in killing the parasites that cause malaria, one of the most serious diseases in the world.

Interesting Facts

• Soaking socks in a solution that contains triclosan can prevent food odor because the compound kills the bacteria that grow on feet and are responsible for the odor.

Words to Know

CARCINOGEN

A chemical that causes cancer in humans or other animals.

SYNTHESIS

A chemical reaction in which some desired product is made from simple beginning chemicals, or reactants.

In spite of its wide use, a number of questions have been raised about the inclusion of triclosan in household and commercial products. One objection is based on the concern that widespread use of the compound may lead to the development of bacteria resistant to antibiotics. Questions have also been raised about byproducts of the reactions by which triclosan is produced and by which it is degraded in the soil. Among those byproducts are a family of organic compounds known as the dioxins, among the most potent toxins known to humans. In addition, studies suggest that cleaning products that contain triclosan are not any more effective in killing germs than is the ordinary procedure of washing one's hands with soap and water. As a result, the Federal Trade Commission has ordered some companies to stop claiming that their product kills germs and reduces disease. The U.S. Environmental Protection Agency has listed triclosan as a possible human carcinogen.

FOR FURTHER INFORMATION

Glaser, Aviva. "The Ubiquitous Triclosan." Beyond Pesticides. http://www.beyondpesticides.org/pesticides/factsheets/Triclosan%20cited.pdf (accessed on November 19, 2005).

"Material Safety Data Sheet." Jeen International Corporation. http://www.jeen.com/cartexe/pdfs/msds%20JEECHEM%20TRICLOSAN.pdf (accessed on November 19, 2005).

Mirsky, Steve. "Home, Bacteria-Ridden Home: Could Antibacterial Soaps Lead to Resistant Strains?" Scientific American (July 19, 1997). Also available online at http://sciam.com/article.cfm?articleID=0009078D-A418-1C76-9B81809EC588EF21 (accessed on November 19, 2005).

See AlsoTriclocarban