[Rockhounds] Luminescence of the Human Body

[Feather]

WOW - what a Science Fair project!!
Feather


Luminescence of the Human Body

Many organic substances fluoresce, so it should come as no surprise that we
humans do too.  Seeing yourself and others under ultraviolet light can be
quite an experience.  Before you run for that ultraviolet light, however, we
offer two caveats:  First, never use a shortwave or midwave ultraviolet
light for this purpose, for it can sunburn the eyes in moments, and also
cause sunburn of the skin.  The only safe light to use is longwave
ultraviolet light, the ones commonly sold as "black lights" in novelty shops
and science stores.  Second, there is no such thing as a beautiful woman,
handsome man, or cute child under ultraviolet light.  The UV lamp is a great
social leveler, turning every one of us into ghouls.

Should you still decide to look at yourself and/or others under ultraviolet
light, here is what to expect.

Parts of the Body
Fingernails:  Your fingernails are one of the most brightly fluorescent
parts of your body and in most people fluoresce bright bluish-white.

Teeth:  Teeth are brightly fluorescent, creamy white.  A person grinning
broadly under longwave ultraviolet light is a sight to behold.  Synthetic
teeth in dentures and caps fluoresce in a range of colors - pink, green,
blue - depending on the material from which they were made.  People who have
had dental work done over a period of decades sometimes have false teeth
that fluoresce different colors.  Modern braces, those made in part of
plastic instead of just metal, often fluoresce brilliantly, and sometimes
quite attractively.

Eyes- The whites of your eyes fluoresce, as others will see if you open your
eyes widely under a longwave ultraviolet lamp.  Your intraocular fluid (the
fluid inside your eyeballs) fluoresces too.  If you look directly into a
longwave ultraviolet lamp (don't ever do this with a shortwave lamp!) you
will see everything through a pronounced haze because you are looking
through an eyeball filled with luminous liquid.

Skin- Your skin fluoresces, not as brightly as your fingernails or eyes, but
enough that you cannot hide under ultraviolet light.  Some parts of your
skin fluoresce more brightly than others.  For example, the palms of your
hands fluoresce more brightly than the backs.  Freckles will appear as dark
spots and typically are more pronounced under ultraviolet light than in
daylight.  Scar tissue often appears more brightly fluorescent than the
surrounding skin.  In general, the paler the skin, the brighter the
fluorescence, as you will see when viewing different parts of your own body,
and especially when comparing the fluorescence of people with markedly
different complexions.

Hair- Light-colored hair, whether blonde or grey, shows a ghostly white
fluorescence.  The brightness of fluorescence dims as hair color darkens and
in true brunettes is hardly noticeable.  Styling mousses and other hair
additives can, of course, introduce fluorescences of their own, so even a
person with black hair can light up in an interesting manner under
ultraviolet light.

Body Fluids and Exudates
    Discussion of this topic quickly engenders the yuck response in many
people.  Suffice it to say that nearly everything your body produces, from
sweat to saliva to fingerprint oils to urine to ear wax to mother's milk to
all those other things, fluoresces - some strongly, some weakly - and that
these things are of more than passing interest to medical researchers and to
crime scene investigators for a variety of good reasons.  Within the field
of criminology, especially, much effort has been expended to study the
fluorescence of these substances and, where possible, to enhance it for
detection purposes.  Fingerprint oils, for example, generally fluoresce
weakly, but suitable chemical treatment can make them fluoresce sufficiently
well that good-quality photographs can be taken of them.

Within the realm of "things to try for fun," the next time you visit a
doctor for a retinal angiogram, which involves injecting a solution of
fluorescein into one of your veins, try carrying an ultraviolet lamp with
you into the bathroom the next time you have to urinate.  Fluorescein is
eliminated from the body through the kidneys, and the results for a day or
so after a retinal angiogram are impressive to say the least.  Similar but
less spectacular results can be had after taking a couple of vitamin B
tablets.

Skin Disorders - Rashes, Parasites, Stains, etc.
    [Later.  Perhaps never.]
Some types of ringworm fluoresce.  Gleason reports orange-fl. stains between
the fingers of habitual smokers.  Much more exists on this topic.  [Develop
later]


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