I apologize in advance for the length of this posting, but I felt that it was
information that might be useful to know regarding glyoxal. I became interested in
using glyoxal as a safer substitute for formalin to harden gelatin when it was
discussed in late '95 on the list. Being cautious, I found a few MSDS's
(manufacturers safety data statements) about glyoxal. After finding that none of
them were exactly the same, I got in touch with Monona Rossol, co-author of the
excellent book "Overexposure". She found some information and has generously
agreed to let me post it. BTW, the oral rat LD50's that I found ranged from 1 to 7
grams/kg, which is quite a lot to ingest, not to mention a large difference in
amounts. In that respect it is safer than formalin, but the other possibilities don't
look like great improvements. It can also, by all reports, be absorbed by the skin.
Draw your own conclusions from this information, but do handle these materials
carefully.
BTW, although unrelated, a recent contributor (this is *not* a flame) mentioned
dire effects from inhalation of silver nitrate (stop breathing) and contact with open
cuts (paralysis). Silver nitrate *is* dangerous, make no mistake; among other
things, it can be fatal if ingested, cause black skin discoloration and cause
blindness with eye contact, but I can find no reference to the above posted
remarks in my Merck's Index or MSDS's. Perhaps these unfortunate victims had
other pre-existing conditions that were exacerbated by the silver nitrate?
Although interesting as anecdotal evidence, what documentation is there to
suggest that these effects are a real and consistent hazard to anyone who
doesn't happen to be hyper-sensitive?
If you would like to find further information about chemicals you are using, or
intend to use, the following net address is a good place to look for MSDS's:
gopher://atlas.chem.utah.edu:70/11/msds If you have a browser such as
Netscape, just look up MSDS.
These are the remarks Monona Rossol made about glyoxal:
Glyoxal. What we have here is an aldehyde. the most comprehensive study of
data on this is:
NNIOSH Current Intelligence Bulletin 55, Centers for Disease Control September
1991, "Carcinogenicity of Acetaldehyde and Malonaldehyde, and Mutagenicity of
related Low-Molecular-Weight Aldehydes."
This study pulls together and summarizes all the research data up to 1991. It
concludes that like formaldehyde, there is animal evidence that acetaldehyde and
malonaldehyde cause cancer in animals. the limited human evidence is
inadequate as yet. there are a few sentences in their conclusions that about says
it all:
"Testing has not been completed to determine the carcinogenicity of the nine
related low-molecular-weight aldehydes discussed in this CIB (acrolein,
butyraldehyde, crotonaldehyde, glutaraldehyde, glyoxal, paraformaldehyde,
propiolaldehyde, propionaldehyde, and valeraldehyde). However, the limited
studies that have been conducted indicate that these chemicals have chemical
reactivity and mutagenicity similar to acetaldehyde, malonaldehyde, and
formaldehyde. Therefore careful consideration shuld be given to reducing
exposures to these nine related aldehydes."
Glyoxal studies:
Mutagenic response -positive in Salmonella typhimurium in vitro in four separate
studies.
Increased DNA synthesis -positive in rats by stomach intubation.
Contact dermatitis positive study in humans.
Add the LD50's data and this is all there is really known about glyoxal. In rats,
7.07ml/kg very toxic.
Monona Rossol, industrial hygienist with Arts, Crafts and Theater Safety
I hope this will be helpful to someone!
Richard Farber