Re: Solvent Safety- Last post from [Bill Davis]

[P3D John W Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Sat, 24 May 1997 13:26:38 -0500
>From: P3D Bill Davis  <bd3d@xxxxxxxxxxxxx>
>Subject: Solvent Safety- Last post from me

>John W Roberts, from Digest 2076:

>>I think you just raised a point that had not been covered in the
>>previous discussion...

>>From my post in Digest 2074:
 
>>They must be used in well-ventilated areas a long way
>>from any source of spark or flames.  Breathing the concentrated vapors from
>>any of them could lead to central nervous system depression or death.  They
>>can be extremely irritating to the skin and eyes. 

>I didn't cover long-term effects because the topic was an individual
>cleaning their own shutter blades, which should be a one-time affair,
>definitely short-term exposure. By recommending  well-ventilated areas I
>tried to address and prevent inhalation side effects like headaches, not
>just address the flammability issues. 

>I didn't wish to inundate the list with pedantic recitations of Permissible
>Exposure Limits, Threshold Limit Values, Teratology, Mutagenicity,
>Ecotoxicology, etc., because 99% of those on the list don't really care how
>much I know about a topic only marginally related to stereo photography. 

Excuse me - I meant the discussion on *criteria for selection* among those
solvents. The Digest 2074 quote addresses the valid safety concerns, but to
me it leaves the impression that you might as well flip a coin to select
among them in terms of health risks from exposure.

My concern was that based on my own exposure to a few of these solvents,
I get the strong impression that some are much more nasty than others, and
also that "adequate ventilation" means very different things for the different
substances. To use an analogy from a field I understand a little better, a
cookbook might include a warning to use hot peppers "with caution". Jalapenos
and Red Savina habaneros are both hot peppers, but if you disregard the advice
with one you'll get a scorched tongue for a few minutes, while if you
overapply the other you may get intense discomfort, watering eyes, and
shortness of breath for half an hour. So a little bit of additional information
in the cookbook might be handy.

Similarly for the solvents - those mentioned appear to have different sets
of symptoms, and at least a 10 to 1 variation in exposure ratings.

Partial information from "Hazards in the Chemical Laboratory" (Ed. S.G. Luxon, 
Royal Society of Chemistry, 1992:

  [All exposure ratings here are listed as "OES short-term"]

Acetone: exposure 1500 ppm, toxic effects include dizziness, narcosis, and coma
Naptha [white gas????]: exposure 125 ppm, toxic effects include irritation,
  can permeate the skin
Toluene: exposure 150 ppm, toxic effects include dizziness, headache, nausea,
  mental confusion, irritation, can be absorbed through the skin
Xylene: exposure 150 ppm, risks include irritation

I couldn't find anything about ketones.

I hope you will relent and at least indicate whether you think there's a
preference among these solvents. It wouldn't be a matter of showing off
what you know, but of providing some useful information to those who want
to recondition their old cameras.

John R


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