Re: Alum
R.Farber/K.Sheridan (Farbsher@inter.nl.net)
Tue, 26 Mar 1996 08:58:03 +0100
>>
>> Peter,Klaus, Sandy
>>
>> 1 There is never any necessity to use formaldehyde.
>>
>> 2 There are plenty of safer ways to achieve the same effect i e hardening.
>>
>> 3 As the strength of the chrome alum solution needed to harden gelatine
enough
>> but not too much, is probably less than one tenth of a gram to a litre, the
>> risks are hardly high.
>>
>>
>Terry, Peter, Klaus, Judy et al,
>
>My original posting on the use of formaldehyde versus chrome alum was
>simply to alert Carole that the later was in fact a very toxic chemical.
>I conclude from my readings from various sources that both formaldehyde
>and chrome alum are toxic and proven carcinogens, and
>in the oridinary ways in which we use them are equally dangerous (or safe).
>With specific reference to Terry's comments above:
>
> 1) Perhaps there is no necessity to use formaldehyde, but
>it is very effective in hardening gelatin, and has a long history of use. In
>my case I use it almost exclusively in carbro sensitizers, which are
>very sensitive to change. I could substitute, but that in exchange for
>considerable experimentation to get back to ground zero.
>
> 2) What are they? Glyoxal? Others? Is there a history of long
>term use? What scientific data is this based on? And what about the
>science that assured us that Mad Cow Disease posed no risk to humans?
>
> 3) Yes, diluted as in practical use I am sure that chrome
>alum poses no great risk, and for that reason I continue to use it, as
>I do Pyrogallic acid, which is also a dangerous chemical. But there is
>also a risk in mixing the *dry* chemcals into solution. How much of
>a known carcinogen can one inhale safely? 1/10000 of a gram, 1/1000
>of a gram, 1/100 of a gram?
>
>Sandy
>Sanking@hubcap.clemson.edu
>
>
>Hello,
Regarding glyoxal, see my posting from Monona Rossol in the February
archive. For chrome alum,BTW, the TLV (threshold limit value) set by OSHA
is 0.5mg (that's 0.0005 of a gram) per cubic meter. Rossol, one of the
co-authors of Overexposure, notes that health hazard warnings for most of
the chemicals used in photography are based on very limited short-term
animal studies. Long-term animal studies or significant human data are
rarely available.
This topic can go on indefinitely, but there are but two options: don't use
the material at all, or make a rational informed choice and use the material
as safely as possible. For further information see the IARC monograph on
evaluation of carcinogenic risk of chemicals to humans, Volume
23,Lyon,France, IARC 1980.
To help with the decision making process, you can contact:
Arts, Crafts and Theater Safety, Inc. (ACTS)
181 Thompson St.#23
New York, NY 10012
Telephone 212 777 0062
You can speak with Susan Shaw or Monona Rossol the authors of Overexposure
for further information, both technical and general, at no charge.
The Canadian version of this is:
Ontario Crafts Council Resource Centre
346 Dundas Street West
Toronto, Ontario M5T 1G5
>
MSDS's can be obtained from Enviro-net as well as other net sites
http://www.enviro-net.com/technical/msds/ Look for yourself!
Happy Printing,
Richard Farber