Cleans hot water better than cold water



New Brunswick - The popular belief that hot water helps clean hands could not be confirmed in an experimental study. The temperature of the water had no effect on the removal of germs. Antimicrobial additives in the soap also had no advantages.

The US Food and Drug Administration (FDA) requires food companies and restaurants to keep hot water pipes at least 100 degrees Fahrenheit (38 degrees Celsius). This is to improve hand cleaning, which is mandatory when handling food. Donald Schaffner from Rutgers University in New Brunswick and colleagues have now tested in an experiment whether this requirement is necessary.

They asked 20 people to wash their hands with water that was 15 degrees Celsius, 26 degrees Celsius, or 38 degrees Celsius. Before washing, the researchers infected the hands with a non-pathogenic strain of E. coli. After washing, contact samples were examined in the laboratory.

Result: The temperature of the water had no influence on the effectiveness of the washing process. The use of an antimicrobial soap (with 1 percent chloroxylenol) did not have a better effect than a conventional soap. It was more important that the washing process took at least 20 seconds (equivalent to two stanzas of Happy Birthday) and that the people cleaned their hands thoroughly. This includes using enough soap and cleaning the palms, backs of the hands, the areas between the fingers and around the thumbs individually and, after rinsing, drying their hands with a disposable towel.