From: nreitzel@lonestar.utsa.edu (Norman L. Reitzel   )
Newsgroups: rec.pyrotechnics
Subject: Re: Potassium Nitrate
Message-ID: <1994Jan6.170327.927@ringer.cs.utsa.edu>
Date: 6 Jan 94 17:03:27 GMT

In article <2gfvot$b1d@menudo.uh.edu> crf@cfox.bchs.uh.edu (Chris Fuller) writes:
>William (billw@glare.cisco.com) wrote:
>
>:     I got it from our Chem Lab.  That's also where I got the Ammonium
>:     Dichromate, which doesn't belong anywhere near a school, to begin with.
>
>Now then, I don't blame them for denying the little volcano experiment.
>Hexavalent chromium is suspected of being a .... scratch that - almost
>certainly a strong carcinogen.  It has no place in public school labs....
>especially when this is the only lab the teachers are allowed to use to
>begin with, when there are a variety of equally interesting and yet less
>dangerous experiments that can be substituted and which the students can
>actually participate in.

Oh, FAH!  Hexavalent chromium is a corrosive, and kills cells.  It is a
carcinogen by virtue of the fact that your body has to replace the dead
cells, and any time it has to produce new cells, the risk of oncogenesis
is increased.  Sticking yourself with a pin produces the same effect, as
does sun exposure - which is why sunburn is a cancer risk also.

Where I have a problem is in the term "a carcinogen" - in case you hadn't
noticed, EVERYTHING is a carcinogen.  I'd like more specific data as to
what the risks are.  In the carcinoginicity experiments (LeBlanq, Morris)
on chromium 6+, rats and guinea pigs were ulcerated with Cr6+ continuously,
and strangely enough developed tumors.  You could have done the same thing
with a hot soldering iron, and gotten the same results.

IMO, the results are not germane to anyone, except possibly chrome platers
who are _very_ sloppy, or (and this is for real) in shops where the chrome
tanks aren't properly ventilated and disperse a chromium mist in the air.
For these people, and there were quite a few of them, labeling Cr6+ as
a carcinogen forced some industries to clean up their acts.  Unfortunately,
civil servants do not seem to understand quantitative risk assessment, and
have decided that "any" risk is too much.

Idiots!  Bureaucrats.

Do you know that the "Environmental" program at my college is a Business
program?  It includes _no_ hard science, not even Calculus or Chemistry.
Boy, these people are going to protect the shit out of us, for our own good.

--------------------------------------------------------------------------
  Norman L. Reitzel, Jr.       |    "When you live beside the graveyard,
  nreitzel@lonestar.utsa.edu   |       you can't cry for every funeral."
  Blue Water Ventures, dba.    |                         Russian Proverb
  ------------------------------------------------------------------------

From: shirriff@sprite.berkeley.edu (Ken Shirriff)
Newsgroups: rec.pyrotechnics
Subject: Re: Potassium Nitrate
Message-ID: <2gl3mo$ki2@agate.berkeley.edu>
Date: 8 Jan 94 01:53:28 GMT

In article <1994Jan6.170327.927@ringer.cs.utsa.edu> nreitzel@lonestar.utsa.edu (Norman L. Reitzel   ) writes:
>Oh, FAH!  Hexavalent chromium is a corrosive, and kills cells.  It is a
>carcinogen by virtue of the fact that your body has to replace the dead
>cells, and any time it has to produce new cells, the risk of oncogenesis
>is increased.  Sticking yourself with a pin produces the same effect, as
>does sun exposure - which is why sunburn is a cancer risk also.

That's not true.  Sunburn is a cancer risk because UV radiation has enough
energy to rearrange bonds in DNA.  UV is known to introduce skin cancer
in experimental animals and it is thought that most non-melanoma human
skin cancers are caused by sunlight.  UV damages the bases in DNA through
several mechanisms, and if the DNA gets copied before the bases are
repaired, the bases may be copied incorrectly, causing a mutation (usually
C->T).  After enough mutations a tumor may arise.

For more information, see for example, Ananthaswamy HN, Pierceall WE,
Molecular mechanisms of ultraviolet radiation carcinogenesis.
Photochemistry and Photobiology, 1990 Dec, 52(6):1119-36.

Ken Shirriff			shirriff@cs.Berkeley.EDU