Colorado State University Extension
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SAFEFOOD NEWS - Summer 2005 - Vol 9 No.4

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Study Highights Effectiveness of Alcohol Gel Sanitizers

by Janice Brown, MS Candidate

Hand washing research recently completed in the Department of Food Science and Human Nutrition at Colorado State University surveyed public beliefs about available hand cleansers and their effectiveness in reducing bacteria from hands. In addition, a hand washing experiment was conducted to determine the effectiveness of three different hand cleansers commonly used in the home.

Consumer Behavior Study:
A 6-item behavioral questionnaire was presented to 100 participants to determine the rationale and knowledge consumers use when selecting specific hand soaps for the home. Consumer responses showed an overwhelming endorsement for the use of antibacterial soaps in the home with little awareness or understanding of the value of alcohol gel hand sanitizers as antimicrobial agents. Most participants believed regular hand soaps were not as effective as antibacterial soaps in reducing bacteria on hands. Researchers also found that regular liquid hand soaps currently have little shelf space on supermarket shelves.

Hand Washing Experiment:
Liquid hand soap, antibacterial liquid hand soap and an alcohol gel sanitizer were evaluated for their effectiveness in reducing live bacteria on hands using a 20-second hand washing procedure. Participants (n= 90) were given step-by-step instructions on how to wash their hands in the study. To better illustrate differences between the three hand agents used, participants were instructed to pat-dry their hands with a paper towel rather than use a rubbing action which might cause further mechanical loosening of bacteria. The alcohol gel stations were set up in a similar manner as the hand soap stations, but water was not used to wet or rinse hands. Participants were told to put the alcohol gel on their hands, then rub them together for 20 seconds to disperse the alcohol gel evenly on the hands and wrists and to allow the alcohol gel to dry.

While bacterial reductions were seen using all three hand cleansers, significantly greater reductions (P<0.05) were seen using the alcohol sanitizing gel than the two liquid hand soaps. The liquid hand soap and antibacterial hand soap did not differ in their effectiveness in reducing bacterial counts (p>0.05). (see Figure 1).

Figure 1. Comparison of the effectiveness of hand washing procedures using liquid hand soap, antibacterial hand soap and alcohol sanitizing gel in reducing bacterial counts on hands. a-b, bars with different letters are significantly different (P<0.05)

Conclusions:
Consumers are not well informed about the use and efficacy of hand soaps and are not aware that they may be able to reduce hand bacteria as effectively with plain soap and water as with antibacterial soap. Under the conditions of this study, the alcohol gel was more effective than either the antibacterial or regular hand cleansers in destroying bacteria; however, this product must be used on debris-free hands. All three products used in this study reduced live bacteria on hands, which is the goal of a successful hand hygiene regime.

1. Source: Brown, J.M., 2005. Effectiveness of antibacterial hand soap and alcohol gel sanitizer to disinfect hands in the home. M.S. professional paper. Dept. Food Science and Human Nutrition, Colorado State University, Fort Collins, CO

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