Re: Cheap Shot -- or - UV rays, red plants or red skin

["S. Hieber" <shieber at yahoo_com>]

Steven Maier felt that my comments about the potential
risks of using Ultraviolet light in aquaria was a cheap
shot:

> >Scott Hieber Wrote:
> >To that I would add, and how do you do it without
> damaging
> >your retinas and causing undue risk of the other harmful
> >effects of UV.
> 
> >I know some tanning salons say that some UVs are good
> UV.
> >lol
> 
> >Scott H.
> 
> Scott, this might be one of the most narrow minded
> statements in the history
> of aquarium keeping. Perhaps you should subscribe to a
> different list. Maybe
> you can save a few hundred thousand future blind reef
> keepers.

I don't want to get into a p- contest because this is a
serious subject.  And I regret Steve's emotional response
to my comments.  So I'll take it as a suggestion that
further info be produced.

Okay.  What wavelengths are we talking about?  And how
much? Both dose and energy level (wavelength) are key
factors in determining the extent of risk of exposing human
cells to UV.  The shorter wavelengths are higher energy and
more damaging, or damaging at lower doses, than the longer
wavelengths.

And certainly, using something like, say, a philips  G15T8
#046677-30864-3, which consumes 15 watts, about 4.5 of
which is given off as UV-C or a G30T8, which consumes 30
watts and gives off about 11 watts of UV-c, would not be
wise.  Prolonged UV exposure causes cumulative damage to
skin and retinas.  The amount that one can safely receive
from artifical sources is probably less these days, given
that the amounts from sunlight are greater.

OTOH, all fluorescent bulbs give off a small amount of UV
-- some of the UV produced by the electrical flow through
the mercury vapor is not converted to lower energy levels
by the phosphors; a teeny little bit always leaks through. 
A tiny bit indeed since even those bulbs designed and
intended specifically for UV-C only give off about 1/3 of
their energy in the UV-C range.

BTW, the waavelengths typically assigned the A, B, & C
designations are:

UVA 400 nm - 320 nm  (nanometers)
UVB 320 nm - 290 nm
UVC 290 nm - 100 nm

The Medical College of Wisconsin has some info about the
dangers here:

http://healthlink.mcw.edu/article/964647970.html

Some additional info about the risks involved, inlcuding
UVA are provided here by NASA:

http://sunshine.jpl.nasa.gov/1rst%20Tier/References/VITAL.TECH.UV.html

enter all as one line in your browser/


And additional info, including discussion of potential
risks of UVA, B, and C, is here from the FDA:

http://www.fda.gov/fdac/features/2000/400_sun.html


So I guess at a minimum, if suggesting one increases the
amount of UV exposure to make plants redder, greener,
whatever, it's important to say how much UV and at what
energy levels (wavelengths).  As for how much of what
wavelengths present what degree of danger, that *is* a
matter of some controversy.  Those selling SPF creams tend
to argue one way and those selling time under tanning
lights tend to argue the other.  The medical literature is
probably a better source of reliable info and, of course, I
defer to those.  Perhaps one of the M.D.s on our list could
add something more informed.

Scott H.

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