Q. What is the best way to clean kitchen sponges?

A. The kitchen sponge is a handy cleaning tool. Unfortunately, kitchen sponges can also become germ magnets. Since sponges retain moisture, bacteria that can cause food poisoning can stick to sponges after cleanup. Then, when you wipe something up, you're just spreading around the germs.

Recently researchers at the U.S. Department of Agriculture tested several methods of disinfecting sponges. They soaked sponges for 48 hours in a solution made from ground beef and a lab growth medium to attain a high level of microorganisms (about 20 million per sponge).

Next they treated each sponge in one of five ways: soaked in a 10 percent solution of chlorine bleach for three minutes, soaked in lemon juice, or de-ionized water for one minute, heated in the microwave on high for one minute, or placed in the dishwasher operating with a drying cycle. For comparison, some sponges were left untreated.

The treatments that killed the most bacteria were microwaving and running the sponges through the dishwasher. Both methods killed 99.99 percent of the bacteria.

Using the microwave or the top rack of a dishwasher with a drying cycle are convenient ways to sanitize sponges. Be sure the sponge is wet before putting it in the microwave (you can wet it and wring it out so it's not dripping). Microwaving dry sponges can start a fire! Don't use the microwave on sponges that contain metal. Only cellulose sponges (not natural sponges) can be sanitized in the microwave. Be careful when removing the sponge as it will be hot.

Although soaking sponges in diluted solutions of bleach didn't score as high as micro-waving or using the dishwasher in this particular test, it is still effective at killing many types of bacteria that make people sick.

Whether you choose to use the microwave, dishwasher or diluted bleach, it will be better than just rinsing your sponge in hot water.

If you spill juice from raw meat, fish or poultry, you can clean it up with a paper towel that can be discarded. Afterward, you should wash the area with hot soapy water, then sanitize it with bleach and water or a commercial sanitizer.

Ideally, sanitizing should be done each day that you cook food. Discard sponges after two weeks.

Amy Tousman is a registered dietitian and certified diabetes educator with Nutrition Unlimited in Kailua. Hawai'i experts in traditional medicine, naturopathic medicine and diet take turns writing the Prescriptions column. Send your questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; islandlife@honoluluadvertiser.com; or fax 535-8170. This column is not intended to provide medical advice.