MadSci Network: General Biology

Re: How affective are antiseptic soaps?

Date: Sat Jan 16 22:09:37 1999
Posted By: John Carlson, Medical student, MD/PhD (parasitology) , Tulane University, School of Medicine
Area of science: General Biology
ID: 916102886.Gb

Dear Lauren,

Your question is an interesting one because it can only be answered fully by using good scientific technique. In any experiment, there must be a "control" group with which the experimental technique can be compared.

While many people would be content to see that antibacterial soap removed most bacteria from their hands, a good scientist will use a control to understand what exactly removes those bacteria. In this case, a good control would be using soap that did not have any "antibacterial" chemicals added to it.

In fact, a number of studies have been done on common antibacterial soaps showing that although these soaps did remove most bacteria, they did no better than soaps without antibacterial chemicals added. The fact is that plain soap is so effective that after correctly washing your hands, there aren't many bacteria left for the antibacterial chemicals to work on. Also, most antibacterial compounds require that you keep the soap on your hands for a couple minutes, and few people have the patience for that. Antibacterial soaps work well, but because of the soap, and not because of the added compounds.

Soap works well because it is an emulsifier. Emulsifiers break down lipids, which bacteria use to help them stick to the surface of your hands. Scrubbing with soap dislodges not only the bacteria, but also tiny pieces of dirt and other debris on your hands which may harbor bacteria inside.

A common mistake people make in washing their hands is failing to use soap. Simply running your hands under the water won't get rid of the potentially dangerous microbes on them. Another common mistake is that people don't wash their hands long enough. A minimum of 15 seconds should be spent scrubbing your hands with soap. The Centers for Disease Control and Prevention make all kinds of guidelines for the prevention of disease transmission. For hand washing they recommend:

Always use warm, running water and a mild, preferably liquid, soap. Antibacterial soaps may be used, but are not required. Premoistened cleansing towelettes do not effectively clean hands and do not take the place of hand washing.

Wet the hands and apply a small amount (dime to quarter size) of liquid soap to hands. Rub hands together vigorously until a soapy lather appears and continue for at least 15 seconds. Be sure to scrub between fingers, under fingernails, and around the tops and palms of the hands.

Rinse hands under warm running water. Leave the water running while drying hands.

Dry hands with a clean, disposable (or single use) towel, being careful to avoid touching the faucet handles or towel holder with clean hands. Turn the faucet off using the towel as a barrier between your hands and the faucet handle.

Discard the used towel in a trash can lined with a fluid-resistant (plastic) bag. Trash cans with foot-pedal operated lids are preferable.

If you are interested in a comparison of the effectiveness of different soaps surgeons use before and after surgery, I recommend reading a paper entitled Comparative antibacterial effectiveness of seven hand antiseptics, written by S. Myklebust. (Scand J Dent Res 1985 Dec;93(6):546-54). Here is a link to the abstract.

Thank you for your question,


Current Queue | Current Queue for General Biology | General Biology archives

Try the links in the MadSci Library for more information on General Biology.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-1998. All rights reserved.