Triclocarban

OVERVIEW

Triclocarban (TRY-klo-kar-ban) is a fine white powder with a slight odor. It is used almost exclusively as an antimicrobial agent—a substance that kills microorganisms such as bacteria and fungi. Triclocarban is available under a number of trade names, including Cusiter®, Cutisan®, Genoface®, Procutene®, Solubacter®, and TCC®. The compound is an ingredient in deodorant soaps, disinfectants, toothpastes, and other household products. It is also used in hospitals to cleanse and disinfect the skin of patients and medical staff. It remains on surfaces for relatively long periods of time, lengthening the disinfecting action, rather than breaking down fairly quickly like many other disinfectants. Triclocarban can be imbedded in plastics and textiles to create long-lasting antimicrobial surfaces, such as in toys and kitchenware. It is sometimes used in combination with triclosan, a similar antimicrobial agent.

KEY FACTS

OTHER NAMES:

3,4,4'-Trichlorocarbanilide, N-(4-chlorophenyl)N'-(3,4-dichlorophenyl)urea

FORMULA:

C₆H₃Cl₂NH-CONHC₆H₄Cl

ELEMENTS:

Carbon, hydrogen, nitrogen, oxygen, chlorine

COMPOUND TYPE:

Organic

STATE:

Solid

MOLECULAR WEIGHT:

315.58 g/mol

MELTING POINT:

256°C (493°F)

BOILING POINT:

Not applicable

SOLUBILITY:

Insoluble in water; soluble in fats and many organic solvents

Triclocarban works as a disinfectant because it disables an enzyme called enoyl-acyl-carrier-protein reductase, or ENR, that many bacteria and fungi use to make cell membranes. If they cannot make cell membranes, these microorganisms die. Humans do not have this enzyme, so triclocarban is considered harmless to them. The use of triclocarban became more widespread after another popular antimicrobial, hexachlorophene, was banned by the U.S. Food and Drug Administration in the 1970s. Hexachlorophene use was discontinued after the antimicrobial was implicated in the death of infants who had been exposed to the product. In the first years of the twenty-first century, triclocarban and triclosan began to be used less, due to increased concerns about the long-term effects of these compounds on the human body and on the environment.

HOW IT IS MADE

Triclocarban is synthesized by one of two procedures. In one, 4-chlorophenyl isocyanate (ClC₆H₄NCO) is reacted with 3,4-dichloroaniline (C₆H₃NH₂Cl₂) to give triclocarban. The relationship of these two compounds to the structure of the final product (C₆H₃Cl₂NHCONHC₆H₄Cl) is obvious from their chemical structures. In the second method of preparation 3,4-dichlorophenyl isocyanate (Cl₂C₆H₃NCO) is reacted with 4-chloroaniline (ClC₆H₄NH₂) to give the desired product.

COMMON USES AND POTENTIAL HAZARDS

About three-fourths of all liquid soaps and nearly one-third of all bar soap made in the United States contains antimicrobial agents such as triclocarban and triclosan. Research has shown, however, that washing one's hand with plain soap and water provides as much protection from disease-causing organisms as do antimicrobial soaps. It is apparently the action of washing that removes most bacteria. Many public health experts say that antimicrobial soaps are not necessary in normal healthy households.

The growing concern is that the widespread use of anti-microbial soaps may cause harmful bacteria and fungi to become resistant to antimicrobial agents such as triclocarban and triclosan. That could happen if the genes in microorganisms that produce the enzyme ENR mutate, that is, change their chemical structure. Bacteria carrying the new gene might be more resistant to antimicrobial compounds.

Interesting Facts

• Hunters sometimes wash their clothes in detergents that contain triclocarban to kill the bacteria that contribute to body odor. In this way, the animals on whom they prey, such as deer, are less likely to detect the smell of the hunter and flee the scene.
• No triclocarban is manufactured in the United States. It is imported from other countries, primarily China and India.

Triclocarban has been shown to cause contact dermatitis, an allergic skin rash caused by contact with an irritating substance. This effect is of particular concern among infants and small children. The compound has been implicated in illnesses among newborns, and its use in maternity wards is discouraged. However, the compound is effective in treating other forms of skin rashes, such as atopic dermatitis, also known as eczema, because it kills the bacteria that cause the condition. Although the effects of ingesting triclocarban have not been thoroughly investigated, there is some question about the compound's possible carcinogenic effects.

Triclocarban is considered by some authorities to be an environmental hazard, as well as a risk to human health. The compound is released into waterways when it is used for washing and bathing. Although wastewater treatment plants can remove up to 98 percent of the triclocarban in water, public health researchers have found the compound in 60 percent of the U.S. waterways studied. In one study, it was the fifth most common contaminant among 96 pollutants studied. The half life of triclocarban (the time it takes for half of the substance to disappear) is 1.5 years. That means that the compound will remain in water supplies for relatively long periods of time, certainly more than a few years. Although triclocarban is harmless to humans, it can be toxic to some types of aquatic life such as shellfish.

Words to Know

ANTIMICROBIAL

A substance that destroys microorganisms such as bacteria and fungi.

CARCINOGEN

A chemical that causes cancer in humans or other animals.

ENZYME

A complex protein that is produced by living cells and which promotes biochemical reactions in the body.

FOR FURTHER INFORMATION

"3,4,4'-Trichlorocarbanilide." Hazardous Substances Data Bank. http://toxnet.nlm.nih.gov/cgi-bin/sis/search (accessed on November 19, 2005).

"Anti-bacterial Additive Triclocarban Widespread in U.S. Waterways." Johns Hopkins Bloomberg School of Public Health, Public Health News Center. http://www.jhsph.edu/PublicHealthNews/Press_Releases/2005/Halden_triclocarban_triclosan.html (posted on January 21, 2005; accessed January 6, 2006).

Senese, Fred. "What Are Triclocarban and Triclosan (Ingredients in Some Antiseptic Soaps)?" General Chemistry Online! http://antoine.frostburg.edu/chem/senese/101/consumer/faq/triclosan.shtml (accessed on November 19, 2005).

See AlsoTriclosan