Monday, April 23, 2007

Kill those infectious agents part two

In January of this year, I wrote about how researchers from the University of Florida reported that microwaving kitchen sponges (that are soaking wet) for two minutes kills most infectious agents.

Now we kitchen sponge users have a second way to sterilize our cleaning tool: The dishwasher with a drying cycle.

Scientists from the Agricultural Research Services performed an experiment to determine which normally used household methods for cleaning reusable sponges worked.

At the ARS Food Technology and Safety Laboratory in Beltsville, microbiologists Manan Sharma and Cheryl Mudd and two student interns did the testing. First, they soaked sponges at room temperature for 48 hours in a solution made from ground beef and lab growth medium to attain a high level of microbes (20 million per sponge) to simulate a very dirty sponge.

Then, they treated each sponge in one of five ways: soaked for three minutes in a 10 percent chlorine bleach solution, soaked in lemon juice or deionized water for one minute, heated in a microwave for one minute, placed in a dishwasher operating with a drying cycle—or left untreated.

The scientists chose these methods because they're commonly used in most household kitchens. They found that between 37 and 87 percent of bacteria were killed on sponges soaked in the 10 percent bleach solution, lemon juice or deionized water—and those left untreated. That still left enough bacteria to potentially cause disease.

Microwaving sponges killed 99.99999 percent of bacteria present on them, while dishwashing killed 99.9998 percent of bacteria.

Science you can use.


Waldo said...

The thing about microwaving a stanky sponge is that then your house smells like stanky sponge. I tried it once. Never again.

Sarabeth said...

I've always done the dishwasher cleansing method, but when the microwave story was published, I tried it.

I guess my sponge wasn't skanky enough. I didn't notice a smell.

Still, good to know that the dishwasher does the trick. A 0.0001 difference isn't going to keep me from doing it.

Genevieve said...

I've always run the sponges & scrubby pads through the dishwasher (w/drying cycle) -- glad to hear that it is good practice to do so. I also put our toothbrushes in there every now and then.

TDubRN said...

I send them thru the washing machine after 24 hours. We have a lot of sponges at my house. They are also colour-coded for use: blue=dishes, green=floor, purple=bathroom...

And the funny thing is I'm not even a very good housekeeper! I'm just weird about cross-contamination.

TDubRN said...

Oh yeah, and I change the toothbrushes once a month and I don't keep them in the same room with the toilet.

Man, I sound like I'm a weirdo.

Sarabeth said...

TDubRN--No one has tested the washing machine. I'd go with the dishwasher.

You only sound like a halfway weirdo. We all have some habits that others view as odd. Yours just happens to keep mouths out of the toilet. Not a bad one to have.