A recent study of contamination on kitchen towels by researchers at the University of Arizona found that 89 percent contained detectable levels of coliform bacteria and 25.6 percent had detectable levels of E. coli.

In their article published in the September/October issue of Food Protection Trends, the researchers conclude that, “The common occurrence of enteric bacteria in kitchen sponges and dishcloths suggests that they can play a role in the cross-contamination of foods, fomites and hands by foodborne pathogens.”

The study was conducted this year on 82 used kitchen towels collected from random households in five major cities: Chicago, IL; Tucson, AZ; New Orleans, LA; Orlando, FL, and Toronto, Canada. The cities were chosen for their differing weather, ranging from cold to hot and dry to humid.

Besides coliform bacteria and E. coli, the towels were also found to contain Enterobacter cloacae, Klebsiella pneumonia and K. oxytoca.

“If you are using a dirty kitchen rag, you may actually be introducing hundreds of thousands of bacteria,” said Kelly Reynolds, a researcher with the University of Arizona’s Zuckerman College of Public Health in Tucson.

What can a person do to reduce the contamination on their kitchen towels? Frequently wash and replace them and/or decontaminate them by soaking in a bleach solution for two minutes to reduce the bacterial load. But even that won’t do the trick if you don’t thoroughly dry them.

“Detergent washing and drying of kitchen cloths in the kitchen only slightly reduced microbial contamination, and regrowth occurred within 24 hours, since the towels remained damp,” the researchers wrote.

Ideally, kitchen towels should be laundered after each use, they advise. If that’s not possible, dip them in a diluted bleach solution (two teaspoons per gallon of water) between uses and let them dry. Then, wash them in a washing machine at least once per week, preferably on the sanitizing or antibacterial cycle.