From: stan johnson (sjohnson@gwi.net)
Date: 05/03/00-12:09:28 AM Z
** Reply to note from Linda Phillips <linda__phillips@hotmail.com>
Tue, 02 May 2000 22:46:10 -0500 (CDT)
> How did these rumours of dichromate hazards get started, anyway?
> Urban legend? Well, that's the last time I ever fall for THAT one.
> MSDS indeed!
Toxicology is a somewhat complex and esoteric subject burdened with
incomplete information and approximation. And obfuscated by jargon.
But that's reality. If you want a reasonably factual discussion of the
dangers and lack of dangers of chromium, I suggest you look at the
EPA's IRIS database entry for chromium:
http://www.epa.gov/ngispgm3/iris/subst/0144.htm
A similar but IMO much more readable document is at:
http://risk.lsd.ornl.gov/tox/profiles/chromium.shtml
The latter has an executive summary....
A search with Google or other good search engine will find analogous
info for many (but not all) chemicals. Generally, I think, you'll find
studies on substances that have some harmful effects at some level.
Those that are clearly not harmful won't be studied, for obvious
reasons. Nor will those that are not seen except in a few isolated
places, like darkrooms...
The emphasis is on chemicals that occur in industrial settings. You'll
note that the most severe injuries, and most studies, are reported at
workplaces. That's largely because that's where the highest exposure
levels for the greatest number of hours [per week, say] are generally
going to occur, and thus the greatest incidence of injury, or its lack, as
the case may be.
For all substances presenting an identified hazard, except
carcinogenicity, there will be one or more lower limits of concern
identified. You'd have to make a careful guess to translate these into
realistic darkroom numbers; that might be the most difficult part of the
whole process--evaluating your exposure to compare with 'safe' and
'unsafe' levels. Also keep in mind that the government is more willing
to accept risk to workers than you might wish for yourself. And
especially keep in mind that these numbers are for adult males; not
fetuses nor children.
All of this is human-health oriented. It says nothing about any other
environmental effects. There are other databases of that sort.
stan
-- Stan Johnson sjohnson@gwi.net 05/03/00 02:09am
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