About this Article
Written by: Stephanie Angkadjaja
Written on: December 1st, 2007
Tags: chemical engineering, health & medicine
Thumbnail by: Peter Galbraith/SXC
About the Author
In the Fall of 2007, Stephanie Angkadjaja was a sophomore majoring in Chemical (Environmental) Engineering. She likes watching football and basketball, collecting sneakers, and traveling to new countries.
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Volume IX Issue I > What Makes Antibacterial Soap Antibacterial?
Germs are everywhere, so it's no surprise that antibacterial soaps, hand sanitizers, and lotions are as well. Despite this, consumer knowledge of Triclosan (the active ingredient in many antibacterial products) remains vague at best. A biochemical explanation of how Triclosan disables bacteria will give consumers a more scientific understanding of a product they use so often. After a closer look at how bacteria develop resistance to Triclosan and other antibacterial agents, consumers will learn that the ingredient is a double-edged sword. Will consumers want to continue using antibacterial products at the risk that those products will no longer be effective? Consumers will also learn of the adverse reactions Triclosan has with water to form chloroform, a possible carcinogen, and with sunlight to form dioxins, known endocrine disruptors. Because of the negative trade-offs associated with Triclosan, consumers should consider antibacterial products that do not use Triclosan and instead use ethyl alcohol as the active ingredient. Washing hands with plain soap and water the old-fashioned way is another reliable option.

Ewww! Germs!

Peter Galbraith/SXC
Figure 1: How many times a day do you wash your hands?
In the 2004 film The Aviator, Leonardo DiCaprio portrays Howard Hughes, the famed 20th century Renaissance man with obsessive-compulsive​ disorder and a general paranoia of all things unclean. Scenes in the film show Hughes repeatedly washing his hands; the real-life Hughes, who lived in the mid-1900s, was known to pick up objects with paper towels in order to avoid germs. Today, pharmaceutical companies and the personal hygiene industry cater to the public's similar obsession with cleanliness by marketing antibacterial soaps, gels, and lotions (see Fig. 1). The U.S. consumer demand for antibacterial products is projected to increase $8 million from 2005 to $136 million by 2009 [1].
What is the common active ingredient in these products that is popularly claimed to kill "99.9% of germs,"and how does it work? The secret weapon is Triclosan, a potent synthetic chemical. Although effective, the controversial chemical ironically contributes to bacterial resistance, decreasing its future effectiveness against bacteria. Potentially toxic side effects linked to Triclosan have also raised concerns among environmental protection and consumer advocacy groups. Consumers must be aware of the trade-offs associated with using Triclosan-based products.

A Quick Overview of Triclosan

Triclosan is classified as a broad-spectrum antimicrobial agent because it is effective against a wide range of microbes; the term antimicrobial implies that the chemical is antibacterial, antifungal, and antiviral [2]. Because Triclosan is extremely powerful, very low concentrations can effectively kill bacteria. For example, Colgate toothpaste lists 0.30 % as the percentage of Triclosan on their label. Although the percentage is almost negligible, 0.30 % is sufficient to qualify Triclosan as an active and powerful ingredient. In addition to soaps, Triclosan is found in mouthwashes, face washes, deodorants, toothpastes, and many other household products [3].

Biology 101

Understanding how Triclosan functions requires some rudimentary knowledge of biology, namely the interactions of cell membranes, fatty acids, and enzymes.
The cells of all organisms, including bacteria, require a cell membrane to survive. The cell membrane is a critical barrier that selectively allows oxygen, nutrients, and wastes to permeate and leave the cell [4]; it is the "edge of life, the boundary that separates the living cell from its nonliving surroundings" [4]. Without a permeable cell membrane, a cell would simply die. For example, wastes would not be transported out of the cell, causing toxins to accumulate and poison the cell. Curiously, it is precisely this function of the cell membrane that Triclosan is engineered to immobilize. Fig. 2 shows the important components of the cell membrane, including the lipid bilayer and proteins embedded in the bilayer that facilitate transport in and out of the cell.
Fi​gure 2: Cell Membrane Structure.
The lipid bilayer holds the cell membrane together. Lipids, or fatty acids, are long hydrocarbon chains essential to cell membrane growth and function. Triclosan immobilizes the cell membrane by stopping the process that elongates these chains.