I just addressed the issue of disposing dichromates in a previous post,
but I wanted to say a few things about personal safety and hygene when
handling dichromate solutions.
If anyone is allowing dichromate to touch their skin enough to stain
it, then they are letting themselves in for an eventual allergic
reaction called contact dermatitis. Like all allergic reactions, the
amount of exposure necessary before the manifestation sets in varies
from person to person, but once it starts, it can make your life
miserable in the darkroom. You will find that contact with even more
common darkroom chemicals will cause outbreaks (eg metol poisoning).
Most people I know who have developed this problem (mostly from
exposure to metol, though dichomate exposure seems to hasten the onset
of it) eventually have to give up any darkroom work, though I did meet
someone who told me that after six years of avoiding the darkroom he
was able to develop film and prints again.
Another area where dichromates can enter your body is through the
lungs. This is even more serious than skin contact as it gets right
into your blood stream. I've known a person who made himself seriously
ill spray painting cyanotype emulsion w/o a respirator (it only took
one time). So, handle powdered dichromates with extreme care, that goes
especially for whoever was letting their dichromate solution evaporate
in order to keep from putting it down the drain. Don't let your well
intentioned idea cause you personal harm.
Please, I hope no one seriously considers a dichromate solution
"benign" or is so casual as to handle it unprotected. I've worked with
many processes that required dichromates and I've stayed healthy (so
far :-) because I always handled it with respect.
There is a lot of literature describing the toxicity of dichromates and
how to handle it safely. Don't let ignorance and the absence of
immediate consequences lull anyone into creating harm to yourselves or