>Precisely. Which is why I find those "photo hazards" books useless. Each
>substance is described in worst-case terms, often against what I know from
>my own experience.
There is a fatal amount of oxalic acid in 10 pounds of spinach. Read the
MSDS on oxalic acid and Popeye's a dead man. This points up the great
imprecision in the word "poison". There are about a half a dozen ways that
things can be poisonous. Oxalic acid kills by packing up the kidneys with
calcium oxalate. The body deals with the normal amounts of oxlalic acid
ingested by producing natural chelates in the blood to dissolve the calcium
oxalate. Doctors treat excess oxalic acid poisoning by putting EDTA in the
bloodstream. EDTA works on calcium like its elemental cousin iron by making
it more soluble.
I have customers who treat potassium oxalate developer (similar in effect to
oxalic acid) as if it were plutonium or something and then probably go home
to a meal with a heaping serving of mustard greens or spinach. Just think of
what would happen if the MSDS was packaged with the spinach or greens!
Dick Sullivan
Bostick & Sullivan
Santa Fe, New mexico