
Cleaning a Dirty Sponge Only Helps Its Worst Bacteria - aaronbrethorst
https://www.nytimes.com/2017/08/04/science/sponges-bacteria-microwaving-cleaning.html
======
cstross
If you want an _effective_ means to disinfect a sponge, it's not unreasonable
to turn to the standard for sterilizing intravenous infusion fluids
(pharmaceutical grade sterilization) back in the 1980s. That was designed to
reduce a bacterial titre of 1 million organisms per ml down to one organism
surviving per million litres, in other words by 15 orders of magnitude. And
you can achieve this in your own kitchen quite easily.

The trick is to use saturated steam at 1 bar overpressure — a pressure cooker
at 15 psi will do this — for 15-20 minutes. (Pharmaceutical grade autoclaves
are just pressure cookers that operate on a large scale.) 1 bar overpressure
corresponds to saturated steam at a temperature of 121 degrees celsius and it
makes a _real_ mess out of anything with a cell wall or proteins. This is a
whole lot more effective than merely boiling your sponges at standard
atmospheric pressure, let alone the microwave-and-pray method.

(Note: I'm going from third-of-a-century-old memory of pharmaceutical
manufacturing standards here, rather than an actual citable source. Confirming
it is an exercise for the reader and actual specifics may vary. A sterilized
sponge, no matter how thoroughly boiled, may still contain residual toxic
compounds left from bacterial decomposition. And as I allowed my professional
registration as a pharmacist to lapse a _long_ time ago this is not
professional advice.)

~~~
SAI_Peregrinus
You need to be able to hold the sponge above the water and air levels so it's
in the steam. Real autoclaves either vacuum out the air or have some other
method to keep the air from insulating the item being sterilized. One could
construct a small wire stand to hold the sponge near the top of the pressure
cooker, that would probably help.

~~~
shalmanese
Why does it need to be in the steam? Both the steam and the water are at 121C
and water is a lot more effective at heat transfer.

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brilee
News at 11:

When you kill bacteria via technique X, some bacteria are affected by it more
than others. Since not all bacteria are killed, this leads to the enrichment
of some types of bacteria.

When a scientist took the most populous bacteria and scoured the encyclopedia
for any way in which this bacteria could possibly be dangerous, he finds that
"It is widespread in nature and lives on the human skin. It can cause
infections in people with weak immune systems.", which is about par for the
course.

Scaremongering ensues.

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ChuckMcM
It's where I keep my pet tardigrades. :-)

It always amazes me the traction this sort of story gets. We've been cleaning
hands and dishes and counter tops with towels and sponges for hundreds of
years, and the more we worry about the bacteria, the worse we make things.

Trust that we've evolved to live in bacteria filled environments and not die
horribly.

~~~
sslayer
You can think of it this way as well - breathing pure oxygen sounds good in
theory, but the reality is, it would kill you.

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giardini
How about a new product, "probiotics for your sponge", i.e., a dose of
"healthy" bacteria to keep the bad ones at bay?

~~~
lioeters
Living sponges, possibly bioengineered, with an immune system that keeps
itself healthy/clean?

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scaryclam
Isn't it obvious to most people that sponges (damp, room temperature
environment) are bacteria ridden?

I use mine to get food off of the dishes, and then rinse the dishes in running
hot water. There's no way I'm expecting the sponge to be bacteria free.

------
exhilaration
The entire article is based on people trying to disinfect sponges using pretty
ineffective means (like microwaving???), we dump boiling hot excess water from
our tea kettle onto our dish washing sponge / scouring pad. I'm skeptical than
anything survives that.

A better headline for the article would be "most people don't know how to
properly disinfect their stuff".

I did enjoy the comparison of used sponges with human feces, the article is
definitely worth a read.

~~~
faitswulff
Boiling was specifically mentioned in the study. Previous studies only
measured the bacterial load, but not the bacterial composition. Apparently the
worst types of bacteria continue to survive and repopulate the sponge in
greater numbers:

"Sanitation by boiling or microwave treatment has been shown to significantly
reduce the bacterial load of kitchen sponges19, 21 and can therefore be
regarded as a reasonable hygiene measure.

However, our data showed that regularly sanitized sponges (as indicated by
their users) did not contain less bacteria than uncleaned ones. Moreover,
“special cleaning” even increased the relative abundance of both the
Moraxella– and Chryseobacterium–affiliated OTUs (Fig. 3B). Presumably,
resistant bacteria survive the sanitation process and rapidly re–colonize the
released niches until reaching a similar abundance as before the treatment
(Fig. 6A). This effect resembles the effect of an antibiotic therapy on the
gut microbiota40, 41, and might promote the establishment of higher shares of
RG2-related species in the kitchen sponges.

Although further analyses, including controlled sanitation experiments, are
needed to substantiate these findings, our data allow careful speculation that
a prolonged application of sanitation measures of kitchen sponges is not
advisable."

\- "Microbiome analysis and confocal microscopy of used kitchen sponges reveal
massive colonization by Acinetobacter, Moraxella and Chryseobacterium species"
[https://www.nature.com/articles/s41598-017-06055-9](https://www.nature.com/articles/s41598-017-06055-9)

~~~
duozerk
I wonder how freezing the sponge for 24+ hours would compare.

~~~
andai
Does freezing kill bacteria? In school we were warned to always let a chicken
fully defrost before cooking it, otherwise the center doesn't cook properly
and salmonella (which presumably survived being frozen) will survive the
cooking.

~~~
duozerk
Not all of them - which likely means it'd have the same result or worse as the
boiling mentioned above.

I believe freezing is, however, extremely effective again parasites (but there
won't be in the sponge though).

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acconrad
Couldn't you just soak the sponge in bleach? Bleach kills everything and it's
a liquid, which can get to the depths of your sponge.

~~~
fnord123
And now you are cleaning your dishes with a sponge giving off residual amounts
of bleach. Which is poisonous.

~~~
tombrossman
The amount of bleach left on your dishes after washing and rinsing isn't going
to poison you. Also, bleach breaks down to mostly salt and water.

The real problem with using bleach to clean dishes or eating utensils is that
some of us can taste it very strongly, even hours or days later. For example,
the first job I had was at a fast food place and we had one idiot who used
bleach to soak the plastic soft drink dispenser nozzles in overnight, instead
of the provided cleaning solution (which was tasteless). I was the only one
working there who noticed but I knew _every single time_ he did it without
fail.

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t0mbstone
Some amount of bacteria is good for our immune systems. Letting children play
in the dirt, eating their boogers, and all sorts of other gross things that
children do has been proven to result in them having stronger immune systems.

[http://www.telegraph.co.uk/good-news/2016/06/11/our-
obsessio...](http://www.telegraph.co.uk/good-news/2016/06/11/our-obsession-
with-hygiene-is-jeopardising-our-childrens-haelth/)

On the flip side, people who use hand sanitizer all the time? Yep. You guessed
it. They end up having crappy immune systems as a result, and in some cases,
toxicity from over-absorption of the hand cleaning chemicals such as
Triclosan.

[http://awakeningwillow.com/2010/04/27/11-toxic-
ingredients-t...](http://awakeningwillow.com/2010/04/27/11-toxic-ingredients-
to-avoid-in-hand-soap-and-sanitizer-and-safer-options-for-your-family/)

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nonbel
The soapy sponge is just to remove any adhered matter and oils from the dish
so that a smooth surface is left. The real cleaning occurs when the dish
dries. I'm surprised this isn't common knowledge.

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buzzybee
I do microwave the sponge after use, for about 2 minutes so that it's bone
dry. The reasoning is simple: most of the bacteria are going to hang out in
the water. It's still going to be infected, but it doesn't have to be
_disinfected_. It just has to remain close enough to the ambient load of the
kitchen that it doesn't obviously inflame my hands when I pick it up. After
all, my hands are germy too, most of the time. The soap, water, and pressure
applied during cleaning are supposed to do most of the work.

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josho
What a frustrating article. Did the research show that a boiling water wash to
kill bacteria doesn't work, or that some peoples techniques don't work.

~~~
WalterSear
That no cleaning method they tried works.

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CodeWriter23
We store our sponge vertically in a glass with slanted sides. The sponge stops
about 1-1/2" before the bottom. The sponge drips dry after every use,
depriving bacteria of the "wet" they need to thrive. It surely doesn't kill
all bacteria but it takes about 2 months before the sponge gets into the ewww
zone, which from my standards, greatly extends sponge life over storing them
flat.

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totallynotcool
In sterile processing we toss brushes, albeit not exactly a sponge, daily- if
not more often- because of the bio-burden/micro-organism build up and
efficacy. At home I'm a bit more relaxed as most utensils are only touching
semi/non-critical tissue but i try to stay clear of anything that holds
moisture for cleaning; unless I'm using it with a disinfectant ala bleach.

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andai
“Now I’m an expert in how to clean sponges,” said Dr. Egert, who wants to
compare disinfection methods in a follow-up study. “I’m waiting for the sponge
industry to call me.”

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wiradikusuma
How about sponge with soap?

I use soap when washing dishes, and after I'm done, I just leave it there (I
don't clean the soap from the sponge).

~~~
stephengillie
(Non-antibacterial) soap just sticks to bacteria, making them more slippery,
so they can be washed away. They're still alive in the drain and septic/sewer.

But soap doesn't just magically do this - it has to be foaming, as scrubbing
allows the soap molecules to magnetically organize. As the hydrophobic soap
molecules stick to the non-polar bacteria, they form a bubble shell that's not
unlike a cell wall. To produce this foam with normal hand soap takes ~20
seconds of rotational scrubbing - a soap- _Rasengan_ , if you will.

Bacteria are in everything, including every breath of air and gulp of water.
Our immune system kills the ones which get through our small intestine's mesh
system.

~~~
koolba
Is it possible to use electricity to kill bacteria? A soaked sponge would be
conductive enough to pass a current through. Essentially a sponge _Chidori_.

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majkinetor
Why would anybody clean a spounge god damn it, its not like they cost a
fortune.

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tryingagainbro
OK, so how do I wash the dishes by hand? Use e thinner cloth?

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sjg007
Just wait until they study underwear.

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sprash
I read somewhere else that the best way to kill bacteria in sponges is to
microwave them for about 30 seconds.

~~~
dguo
I thought the same thing, but the first line of the article is "Stop. Drop the
sponge and step away from the microwave."

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stcredzero
I've switched my household over to using these instead:

[http://a.co/aQC3ljK](http://a.co/aQC3ljK)

The reason why sponges are great for bacteria is their ability to hold water
in little pockets. These dry out completely and much faster. The bacterial
load won't be zero, but I suspect it will be much better than with sponges,
especially with some judicious disinfecting. (Which I will be using the
pressure cooker for!)

