[Slack, Steve]

Slack, Steve  asked the Naked Scientists:
   
If urine is sterile, why do we have to wash our hands after going to the toilet?
 
Steve Slack
Hampshire

What do you think?

[freecw]

I don't.
I think its because other people use the restroom and when they do some go number 2, which is not sterile. The bacteria from that is then transferred all over the place making it a good idea to wash your hands if you touch the doorknob or other things found in the restroom.
Also its just good practice to wash your hands every now and then to limit growth of bacteria that may end up in your body when you rub your eyes or touch your mouth or something like that.

[Kryptid]

Urine isn't always sterile. Sometimes bacteria may be present if the person in question has a urinary tract infection. Likewise, rabies virus can be excreted in the urine (although that's obviously usually not a concern for most people).

[chris]

Urine is sterile when it leaves the bladder (in a healthy person) but, depending upon the gender and anatomy, picks up bugs on the way out. In women, as the stream passes over the labia, it inevitably collects a rich menagerie of bacterial flora that naturally congregate in that area. This is why when females are required to provide a urine sample they are always encouraged to part the labia, pass some urine into the toilet to flush the urethral opening clean and then to pee into the pot to achieve a "clean catch". In uncircumcised men the foreskin carries a substantial bacterial burden of flora and should be retracted before providing a specimen. Circumcised men, in the absence of a UTI or other infection, generally have as close to sterile urine as it's possible to get.

But it's not the urine that dictates the need to wash hands when using the toilet - it's the filth that other people have left on the surfaces that you touch - like the door handles - when you are in there.

Chris

[Geezer]

Urine is sterile when it leaves the bladder (in a healthy person) but, depending upon the gender and anatomy, picks up bugs on the way out. In women, as the stream passes over the labia, it inevitably collects a rich menagerie of bacterial flora that naturally congregate in that area. This is why when females are required to provide a urine sample they are always encouraged to part the labia, pass some urine into the toilet to flush the urethral opening clean and then to pee into the pot to achieve a "clean catch". In uncircumcised men the foreskin carries a substantial bacterial burden of flora and should be retracted before providing a specimen. Circumcised men, in the absence of a UTI or other infection, generally have as close to sterile urine as it's possible to get.

But it's not the urine that dictates the need to wash hands when using the toilet - it's the filth that other people have left on the surfaces that you touch - like the door handles - when you are in there.

Chris

Bleedin' heck!

Forget all the "sex education". I think they better start off with "how to take a whizz" education first.

[techmind]

I imagine it is quite possible for some faecal particles to be transferred from one part of the underwear to another (especially if pulled down/up during the course of the day) so the male organ may not be quite as perfectly clean as you'd like to think...

[CZARCAR]

recently heaRD that urine is good for killing mold in the bathtub? so what else can urine do?

[CliffordK]

recently heaRD that urine is good for killing mold in the bathtub? so what else can urine do?

Lots of things.
Reports are that they used it to make gunpowder during the US Civil War.

[Geezer]

recently heaRD that urine is good for killing mold in the bathtub? so what else can urine do?

Lots of things.
Reports are that they used it to make gunpowder during the US Civil War.

Quite likely they did http://www.thenakedscientists.com/forum/index.php?topic=610.msg358912;boardseen

[Don_1]

It is also said to be an aid to the breakdown of organic matter in a compost heap, though only male urine in this case. Perhaps Chris's answer is a clue as to why. Anyway, you wont catch 'er indoors popping down the garden path to wee on the compost heap, nor me either. Reason - we don't have a compost heap.

[Mr. Data]

Slack, Steve  asked the Naked Scientists:
   
If urine is sterile, why do we have to wash our hands after going to the toilet?
 
Steve Slack
Hampshire

What do you think?

Because urine (which may be sterile) is only sterile up to a point I would surmise. Have you ever noticed public area's with a strange yellow mesh of almost clear deposits round the urinal toilet? This is bacteria, and I bet a lot of it is harmful!

[Bored chemist]

Even if we accept your un-evinced assertion that the deposit is made up of bacteria, whic I doubt, I bet a lot of those bacteria are not harmful.
Most bacteria are harmless.
The ones growing on or near a urinal will have evolved to be suited to those conditions. The conditions in the human body will be markedly different. Typically 15 or 20C hotter for a start.

[CZARCAR]

true= showered this morn & felt slimy under my feet [never clean it] so i pissed on the slime & after rinsing,the underfoot slime diminished! Heard this inspiration from Steph Miller radio show, kinda

[Ashley VC]

Can you catch any std's from a females urine??

[Donnah]

Please wash hands after peeing because I don't want to shake hands with someone who's just wiped or shaken their private parts.  I read a study once listing the number of vaginas and penises you may be touching on doorknobs.  Yuk!  They're called private parts for a reason.

On the other hand (pun intended), I've heard that the nitrogen in pee is good for plants.  Is this true?

[chris]

Definitely - nitrogen in urine is in a fixed state - unlike the dinitrogen in the atmosphere. As such it is in a biologically available state, which can benefit plant growth. The schoolboy idea that peeing on the stinging nettles will kill them is a massive myth - it will actually make them flourish!

[Bored chemist]

There's enough salt in urine that peeing on plants repeatedly will kill them, I'd not choose nettles as the test  case.

Incidentally, it's said that the definition of a chemist is someone who washes their hands before they go for a pee. (Though I gather this distinction applies to chefs in chilli restaurants too)

[Mirch Masala]

Before discussing the microbiology of urine we should keep one thing in our mind that urine is something that includes the unnecassary metabolic products from our body that are harmful for us that is why it is being excreted.Does anyone wants his/her hands carrying the metabolic waste products of body?. So better wash your hands after passing urine.

[Donnah]

Definitely - nitrogen in urine is in a fixed state - unlike the dinitrogen in the atmosphere. As such it is in a biologically available state, which can benefit plant growth. The schoolboy idea that peeing on the stinging nettles will kill them is a massive myth - it will actually make them flourish!

Sounds like one prankster schoolboy was hoping another would get a little too close to the nettle.

Are nettle stings beneficial in some way?  Young nettles are tasty when they're steamed and buttered...or so I've heard.  How nutritious are they?  Should I be out there peeing on them to increase the yield? [] 

[imatfaal]

Definitely - nitrogen in urine is in a fixed state - unlike the dinitrogen in the atmosphere. As such it is in a biologically available state, which can benefit plant growth. The schoolboy idea that peeing on the stinging nettles will kill them is a massive myth - it will actually make them flourish!

Sounds like one prankster schoolboy was hoping another would get a little too close to the nettle.

Are nettle stings beneficial in some way?  Young nettles are tasty when they're steamed and buttered...or so I've heard.  How nutritious are they?  Should I be out there peeing on them to increase the yield? [] 

Taste like really nice spinach.