The Centers for Disease Control (CDC) have established the 20-second hand washing rule for safety, and the 20 seconds is based in science. Few of us watch the clock while we’re washing, but those of us in the food service industry learned early to “Sing the ‘Happy Birthday!’ song twice.” Or, of course if you’re into technology, you can get the app for your smart phone or smart watch.
ServSafe, the National Restaurant Association’s manager-level food safety course, suggests these five steps:
• Wet hands and arms (up to the sleeve), using warm running water. As of January 1, 2023, the minimum temperature of the water was reduced to 85º F.
The CDC instructs us to turn off the water after this step to conserve water and energy.
• Apply soap according to the manufacturer’s direction and work up a good lather.
• Scrub hands and arms vigorously for 10-15 seconds, scrubbing all around the fingers and under the fingernails.
The CDC suggests that we scrub for a full 20 seconds.
• Rinse throroughly using warm running water.
Wash the soap and microbes away.
• Dry hands and arms with a single-use paper towel or hand dryer.
Some studies have shown that drying with the paper towel adds additional friction, and may actually remove more pathogens that may have been missed while scrubbing.
Now the science…
Soap is a surfactant which gets in between the surface and the soil and lifts the soil away. Scrubbing creates friction which assists in the process. Clearvue Health, www.clearvuehealth.com, is an incredibly interesting online resource which explains a myriad of health-related topics through data. Regarding scrubbing time, they found that scrubbing hands for 5 second removes 98.8% of surface microbes; 10 seconds, 99.3%; 20 seconds, 99.7%; and, 40 seconds, 99.6%.
These data show us there is no significant improvement in microbe reduction between the CDC’s guideline of scrubbing for 20 seconds, and ServSafe’s 10-15. Take added comfort in knowing that not all microbes on the hands to begin with are disease causing, and in food service, we don’t attempt to sterilize (total elimination of pathogens), we just want to reduce pathogens to a safe level.
Keep those hands clean and safe!