US scientists have discovered that microwaving kitchen sponges, cloths and plastic pan scrubbers kills 99 per cent of kitchen germs.

The results of the study are reported in the Journal of Environmental Health.

Gabriel Bitton, Professor of Environmental Engineering at the University of Florida where the tests were conducted said that “Basically what we find is that we could knock out most bacteria in two minutes.” He added that people often put their sponges and pan scrubbers in the dishwasher. This cleans them, but it does not decontaminate them, he said.

Kitchen sponges and dishcloths are a breeding ground for germs such as Salmonella, E. Coli, pseudomonas, staphylococcus and other germs, increasing the risk of potentially fatal foodborne diseases.

Professor Bitton, who is an expert on wastewater microbiology, and his team used a regular off-the-shelf microwave oven to “zap” sponges and plastic pan scrubbers. They microwaved them for different lengths of time, squeezing out the water in between and measuring the microbial load in the water for each duration. These measurements were compared to those taken of water from pads and sponges that had not been microwaved or sterilized in any way.

There were no doubts about the results of the tests. Two minutes in the microwave on full power was enough to kill or neutralize more than 99 per cent of the pathogens that had been living on the sponges and pan scrubbers. The only pathogen that needed longer (about four minutes in the microwave) were spores of Bacillus cereus which causes diarrhea, stomach ache and sometimes vomiting too, with symptoms lingering for about 24 hours.

Professor Bitton said that “the microwave is a very powerful and inexpensive tool for sterilization.” Approximately 90 per cent of American homes have a microwave, making this simple but effective technology within the reach of the vast majority of the population.

In a survey conducted in June last year, the UK’s Food and Drink Federation found that only 12 per cent of people changed or disinfected their kitchen sponge or cloth once a month, and only 6 per cent did it more often.

Food-borne illnesses affect at least 6 million Americans every year, and are responsible for at least 9,000 deaths.

WARNING: To avoid starting a fire if you do this at home, make sure the cloth or sponge is soaked with water, that the water does not boil away (don’t keep microwaving until all the steam has gone), and do it for no more than 2 minutes. And never put metal in the microwave (some cloths and sponges and pan scrubbers, even plastic ones, have metal filaments, don’t put those in the microwave). And finally, use tongs to remove the hot cloth or wait until it has cooled before you remove it or you will scald yourself.

“Microbial Inactivation by Microwave Radiation in the Home Environment.”
Dong-Kyoo Park, Gabriel Bitton, Ph.D., and Richard Melker, M.D., Ph.D.
Journal of Environmental Health Vol 69, No 5, Dec 2006.

National Environmental Health Association (US).

Gateway to (US) Government Food Safety Information.

Written by: Catharine Paddock
Writer: Medical News Today