Re: IS SALIVA CLEANER (MORE STERILE) THAN URINE?

Hello Erin!

Well, hopefully, both your saliva and your urine are sterile, at
least where they're manufactured!  When we refer to things as "sterile," we
usually mean things that don't have microbes (like bacteria or viruses) on
or in them.  In the human body, if there are bacteria or viruses present
where they shouldn't be, you usually get sick.  If urine were not sterile
(at least inside the body), then it's likely that you'd have a urinary
tract infection (your lower belly and maybe your back would hurt, and it
might hurt to pee; you might also have a fever).  If saliva were not
sterile where it was being manufactured in the salivary glands, chances are
the salivary glands would be harboring some unwelcome guests.  The most
well-known kind of salivary gland infection is called mumps, which
isn't as well-known now as it was when your parents were kids, since
there’s been a vaccine for it for about 40 years.  Mumps is caused by a
virus infecting the parotid salivary glands, causing the glands to swell a
lot and conferring upon the unfortunate sufferer a somewhat chipmunk-like
appearance.

For a picture of a kid with the mumps (from the CDC), go here: http://www.nationalacademies.org/headlines/20060428.html

Now, healthy urine and saliva don’t have any bacteria or viruses in
them.  Once these useful bodily fluids, however, make it to the outside of
the body (where the fluids can touch your skin), then they can – and do –
pick up all kinds of normal bacteria (viruses less so, but it’s
certainly possible), making them not sterile at all.

For an enlightening discussion about spit, go here: http://www.kidshealth.org/kid/talk/yucky/spit.html

…and for more on bacteria and urinary tract infections, go here: http://www.kidshealth.org/kid/ill_injure/sick/uti.html