Food Safety Magazine

News | May 31, 2017

Study: Effective Handwashing Does Not Require Hot Water

By Staff

Study: Effective Handwashing Does Not Require Hot Water

Handwashing is a hot topic in the world of food safety. Lack of proper handwashing procedures in foodservice and other sectors can lead to the spread of foodborne illness. Are current handwashing rules in need of updating? A new study suggests it may be time.

According to research released by Rutgers University, cool water is apparently just as effective as hot water in terms of washing away harmful bacteria. For the study, 21 volunteers had their hands covered with a harmless bacteria multiple times over a 6 month period. Each time, the volunteers were instructed to wash their hands at varying water temperatures—60 °, 79 ° or 100 °. They were also asked to use 0.5 ml, 1 ml or 2 ml volumes of soap.

"People need to feel comfortable when they are washing their hands but as far as effectiveness, this study shows us that the temperature of the water used didn't matter," says Donald Schaffner, distinguished professor and extension specialist in food science.

"This study may have significant implications towards water energy, since using cold water saves more energy than warm or hot water," says Schaffner. "Also, we learned even washing for 10 seconds significantly removed bacteria from the hands."

The study appears to indicate that there is no difference between washing hands with cold or hot water, nor does it matter how much soap is used. However, further study would help to decipher what types of soap are most effective at removing harmful bacteria from hands.

"This is important because the biggest public health need is to increase handwashing or hand sanitizing by foodservice workers and the public before eating, preparing food and after using the restroom," says Jim Arbogast, study co-author and vice president of hygiene sciences and public health advancements for GOJO.

Rutgers’ study is an important one for the foodservice industry since the U.S. Food and Drug Administration (FDA) issues handwashing guidelines to individual states about every 4 years or so. Currently, those guidelines instruct foodservice establishments to set plumbing systems at 100 °F for handwashing. If cold water handwashing becomes the norm, businesses could save significantly in terms of energy use.

FDA will convene in 2018 to discuss existing code and modifications. The authors of the study hope that the agency will revise water temperature policy at that time to avoid so much wasted energy on hot water usage.

The Rutgers study appears in the June 2017 issue of the Journal of Food Protection.

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