Ask The Homemaker
The #DeathSponge edition
Dear Jenny: I heard that kitchen sponges are the nastiest thing in the house. Is this true? And can you really disinfect a sponge?
Dear Germaphobe: I’ve seen so much written on this subject that I sometimes think it must be the 21st century’s most pressing issue. There are endless blog posts and pins telling us how to disinfect a sponge and thereby prevent the eradication of human life.
Some say to bleach them. Some claim vinegar will do the trick. Others cry shenanigans and insist that the microwave is the only way to stop the bubonic plague from descending upon us. I’ve heard of using lemon juice, boiling water, ammonia, the dishwasher and even the washing machine.
The problem is that the sponge cleanliness mavens virtually never cite a source. Who says that these methods disinfect or sanitize sponges? Is there data to prove it? Are they just repinning what they saw on a blog that got the information from another blog which got the information from….? You get the idea.
I figured that it made sense that the VeryHotWater of the dishwasher or the SuperNuke capabilities of the microwave could kill off bacteria. We know bleach will kill just about anything in the right concentrations, so that made sense too. But I wanted proof.
I began to dig deep. I found a study conducted by scientists from the USDA’s Food Safety Laboratory and published in a peer reviewed scientific journal  that evaluated five methods of disinfection. I’m feeling pretty good about trusting the results. Scientific method and all that.
Get a glass of wine and read on, or just skip to the results.
What Is Disinfecting?
So when we talk about “disinfecting” our sponges, what does that mean? What are we trying to get rid of? Some nasty stuff, as it turns out. The grossness they were looking for in this study included:
- Escherichia coli O157:H7 – better known as the always fun E. coli
- Campylobacter – which includes C. coli and C. jejuni. C. jejuni is one of the main causes of food poisoning in developed countries
- Salmonella – the one your mother warned you about
- Yeast and molds – blech
Do We Really Need to Disinfect Kitchen Sponges?
Yep. You really do. The study I reference in this article cites many (25 in fact) other studies related to foodborne illness and household kitchen hygiene.
One of their conclusions is that, “Improper domestic food handling and unhygienic practices are thought to be a major factor in sporadic cases of foodborne illness. It is estimated that up to 87% of foodborne disease outbreaks that occurred in the United Kingdom, Europe, Australia, New Zealand, the United States, and Canada originated from food prepared or consumed in the home (Redmon & Griffith, 2003) … Kitchen sponges deserve attention in the household because they can remain wet and serve as a reservoir and vehicle for foodborne pathogens to cause illness.”
But I’ve Never Had Food Poisoning
My mom says we never used cellulose sponges when I was growing up, but I’ve used them all of my adult life. No one in my family has kicked off as a result, but I’m not sure that “no one has actually DIED” is the best benchmark.
You know those times when you’ve had that miserable grumbling in your gut a few hours after a meal? Was it really just because the gravy was too rich? What about that “stomach flu” you had a couple of months ago?
Surprise! Those could very well have been the consequences of consuming contaminated food. Food poisoning doesn’t always (infrequently, as a matter of fact) end up with a hospital stay or a near-death experience. Good ol’ diarrhea and/or upchucking is your body’s rather efficient way of getting rid of the bugaboos.
Now obviously, dirty sponges are not the only way to spread bacteria around in a way that will get into your food, but keeping your sponges clean can certainly help things be more hygienic.
So Why Don’t We Just Throw Away All of the Sponges?
There are alternatives to regularly disinfecting your sponges. You could throw them out every night and start fresh every morning. That strikes me as wasteful (admittedly, this is coming from someone who goes through like eight rolls of paper towels a week #JudgeAway), and expensive.
You could use dish rags instead, but that doesn’t eliminate the bacteria issue (although it may reduce it). You could save the mesh bags that onions come in, wrap them around strands of yarn and knit them into scrubby dishcloths. But, um, yeh. That’s probably not going to happen around here and it doesn’t get rid of the problem all together.
You could use nylon/plastic scrubbies. I don’t have any data on how sanitary they are but when I’ve tried them I’ve found it very, very difficult to get the little food particles (bits of rice, etc) out of them, which grosses me out.
The truth is, I don’t anticipate eliminating sponges from my kitchen any time soon, and lots of y’all probably don’t either, so let’s find out how to create the nastiest sponge ever, and then learn how to keep it from killing us.
How to Make a Death Sponge
You won’t believe what they did to germify the sponges in this study. If you used sponges contaminated like this, I don’t see how you’d survive a week! Prepare to puke. Or just skip to the results. But this is like a train wreck: You won’t be able to look away.
Step 1: Cut lots of sponges into little rectangles
Step 2: Make a beef slurry using raw ground beef, tryptic soy broth (I think I had a bowl of that before my entrée last night), and put it in a stomacher (WTH? I don’t even want to know).
Step 3: Soak the sponges in the slurry and then let them sit out at room temperature for 48 hours.
That’s right. You soak them in raw beef slurry and then leave ‘em out for two days. Pardon me while I go retch a bit.
On my first reading of this study I wondered why they would cause such extreme contamination for tests that are specifically designed to improve sanitation in household use. What sort of people soak a sponge in raw beef juice, leave it out for a couple of days and then wash a glass with it?
My very clever husband noted that perhaps the reason they create death sponges is so that they can be sure to develop really big colony forming units (CFUs). The larger your sample size, the more easily you can measure and compare the results.
Ok Clever Husband. You got me this time. And you do nearly every time, truth be told. But that’s an issue for my self-esteem coach and I to discuss.
What They Tried
The methods they tested:
- Soaking in a 10% bleach solution for 3 minutes
- Soaking in a 2.9ph vial of lemon juice for 1 minute
- Soaking in deionized water for 1 minute
- Microwaving on full power for 1 minute (2,450 MHz)
- Washing on the top rack of a dishwasher with the water heat booster and heated drying feature
- Control (no attempt to disinfect)
The entire experiment was replicated three times, with the results averaged. “Averaged” isn’t quite the right word. Specifically, they used statistical analysis software to, “conduct an analysis of variance and least significant difference mean separation tests (P <= 0.05).”
To keep my head from exploding I’m going to stick with the term averaged.
The Results ↑
You skipped right to this part, didn’t ya? Ok, drumroll then…
The microwave is the winner. It killed significantly more bacteria, yeasts and molds than any of the chemical methods, and significantly more bacteria than the dishwasher (it came out about the same as the dishwasher on the yeast/mold counts).
It’s also wicked easy. After dinner, rinse out the sponge, toss it in the microwave for 1-2 minutes, and then put it somewhere it can get some air circulation. The study used a 2,450 MHz microwave. Mine is only 1,000 MHz so I go with 2 minutes just to make myself feel better.
I’ve read criticism of the bleach, dishwasher and microwave methods.
- Bleach is TheBigEvil. It’s toxic. Yes, yes it is. So is lots of other stuff used at improper dilutions. But that’s another post.
- The dishwasher may not get the water hot enough to sanitize the sponge. The study I cite for this article did not specify the temperature of the water used in their dishwasher. Death sponges “were placed in the top rack of a household dishwasher (portable-convertible model, General Electric) and a normal cycle with the water temperature boost feature and heated drying cycle was executed.” I’m guessing that’s comparable to what the average person uses in their house.
- The sponge might catch on fire in the microwave and burn the house down. Plus, microwaves are a government conspiracy to make us radioactive zombies. A little common sense goes a long way here. Don’t put the sponge in the microwave dry, as noted in this study and another similar study. Make sure it’s wet. Also, don’t put a ball of tinfoil in the microwave. Or a cast iron skillet.
I disinfect my kitchen sponge in the microwave every night after dinner cleanup and leave it on top of the sink area to let it get some air. It’s become part of the evening routine and doesn’t add any time to cleanup. Nuking the kitchen sponge isn’t the only thing you need to do to maintain a clean, healthy kitchen but it makes sense to me. If I disinfect the counters and sink shouldn’t I disinfect a sponge too? I’ll go with a yes on that.
So what do you think? What’s your sponge personality? Do you use sponges in your kitchen? Do you disinfect them? Tweet How To Make a #DeathSponge and/or leave a comment below and let me know!