SEP 18, 2015 4:59 PM PDT

Antibacterial soap doesn't live up to the hype

WRITTEN BY: Kerry Evans
Did you wash your hands today?  Did you use antibacterial soap?  If so, you probably didn’t get the antibacterial benefits you expected.  Sorry.

Researchers from South Korea published a study testing the “real world” effectiveness of antibacterial soap.  The results?  Regular soap was just as effective at eliminating bacteria as soap containing Triclosan, the active ingredient in many antibacterial products, when tested under real world hand washing conditions.

Regular soap is just as effective as antibacterial soap at eliminating bacteria.

Triclosan is a polychloro phenoxy phenol antimicrobial that was developed in the 1960s.  At the low concentrations used in commercial products (up to 0.3%), Triclosan targets a bacterial enzyme necessary for fatty acid synthesis.  It is the most widely used antimicrobial in soaps and other products like toothpaste, shampoo, lotion, kitchenware, and even toys.  It’s also big business.  Americans spend nearly $1 billion on antibacterial soaps annually.  

The authors conducted their study in response to a 2013 statement by the FDA requiring manufacturers to demonstrate that antibacterial products are more effective than products without antibacterial additives. Not to mention, there are conflicting views (Aiello et al. and Montville and Schaffner) when it comes to the effectiveness of antibacterial soaps, and plenty of people are convinced that Triclosan itself is a health hazard (video below).

In this study, published in the Journal of Antimicrobial Chemotherapy, the authors tested antibacterial soap against regular soap in two ways.  First, they tested the ability of each soap to kill 20 different strains of bacteria under conditions that simulated hand washing.  Among these were species of Enterococcus, Staphylococcus, Pseudomonas, and Shigella.  For this experiment, they exposed the bacteria to soap containing 0.3% Triclosan for 20 seconds at either 22oC (room temperature) or 40oC.  In the second experiment, they inoculated volunteers' hands with Serratia marcescens and compared the antibacterial activity of each soap after actual hand washing.  After each experiment, the remaining bacteria were collected and grown on plates to count colonies of surviving bacteria.

Their results showed that Triclosan was more effective at killing bacteria than regular soap, but only after 9 hours of exposure.  (That’s a lot of hand washing.)  Overall, they found no significant differences between the antibacterial activity of Triclosan or regular soap under real world hand washing conditions.  

What’s the take home message?  The next time you’re out to buy soap, don’t bother with the antibacterial stuff.  It seems plain soap works just fine.



Sources: EurekAlert, Journal of Antimicrobial Chemotherapy, FDA, Wikipedia
 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
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