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Author Topic: Should you rinse detergent off dishes after washing them?  (Read 15631 times)

thedoc

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Alan Cluett  asked the Naked Scientists:
   
Chris,

I listen to your session with Redi on 702 on Fridays.

My wife and I differ on how we complete the dishwashing exercise.

I always rinse the cleaned but soapy dishes in clean water before stacking for drying, whilst my wife stacks the dishes directly from the soapy water.

We use biodegradable dish washing liquid.

My view is that the dishwashing liquids contains de-greasers and wetting agents that, if not rinsed off, will contaminate the next plate of food, cup of coffee or tea etc. Over many years this could impact on the internal linings of our mouths, throats and, especially, stomachs.

Am I being paranoid*?

Alan.

* in the sense of "unreasonably or obsessively anxious, suspicious, or mistrustful"?

What do you think?
« Last Edit: 12/03/2012 08:51:01 by _system »

ashugg

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Re: Should you rinse detergent off dishes after washing them?
« Reply #1 on: 12/03/2012 09:25:52 »
I say definitely yes because I find the taste of dish washing detergent to be disgusting. Even your nice biodegradable one.

CliffordK

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Re: Should you rinse detergent off dishes after washing them?
« Reply #2 on: 13/03/2012 07:44:46 »
I'm all for a good rinsing...  I suppose if you towel dry the dishes, that will take off most of the soap.  Or, you could stack, then spray-rinse.

Sprool

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Re: Should you rinse detergent off dishes after washing them?
« Reply #3 on: 14/03/2012 12:49:59 »
any small traces of detergent in your mouth will be washed away when you eat and drink, they will get mashed to bits in the stomach full of hydrochloric acid and any surviving traces will be washed through your guts, eventually finding their way back into the drainage system via your toilet bowl. At least they may in some small way contribute to keeping the bowl clean

peppercorn

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Re: Should you rinse detergent off dishes after washing them?
« Reply #4 on: 14/03/2012 13:08:28 »
Isn't the rinsing process just using hot water/steam drying?
There's usually a rinsing 'agent' in the dishwashing tablet but I had thought this just stopped smearing (just a softener?) and left no chemical residue behind anyway.

I have heard that washing-up liquid can have carcinogenic properties and I would always rinse suds off plates, etc before stacking. Although it's probably just an urban myth.

Bored chemist

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Re: Should you rinse detergent off dishes after washing them?
« Reply #5 on: 14/03/2012 20:10:39 »
"I have heard that washing-up liquid can have carcinogenic properties"
I can think of relatively few things that couldn't be substituted for "washing up liquid" in that sentence.

The detergents are of low oral toxicity (Gosh!).
They don't taste very nice (even the lemon scented ones).
On the other hand, if those detergents get into the bloodstream they are quite toxic. However if there's a big enough hole in your stomach lining for that to be an issue, then you already have a much bigger problem than soap.

SeanB

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Re: Should you rinse detergent off dishes after washing them?
« Reply #6 on: 14/03/2012 20:36:39 »
They do tend to have a laxative effect in many cases........

A case of them doing double duty, cleaning the plate and a while later doing the same to you from the inside.

CliffordK

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Re: Should you rinse detergent off dishes after washing them?
« Reply #7 on: 15/03/2012 03:18:13 »
I'm not quite sure what is in the squeeze bottle of detergent.

However, you can make lye soap if you wish.  100% natural, and it should be safe to eat it too  ;)

charkol

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Re: Should you rinse detergent off dishes after washing them?
« Reply #8 on: 19/03/2012 01:38:06 »
Aside from the chance of gaining a stomach ache and/or diarrhea, the basic mechanism of how soap works would be enough to get me to rinse off the dirty dishwater.

Soap removes grease and dirt(salty, sugary) things from your dishes.  Each lauryl (soap) molecule has a non-polar end for greases and oils, and a polar end for salts and sugars.  These soap molecules surround the oils and dirts by which ever end of the molecule is needed. 

So when the dishes are not rinsed, those greases and dirts are being left on your dishes, with the 'bonus' of the soap as well.  Hope this helps your proposal.

 

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