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Re: Vinyl chloride odor
At 04:37 PM 11/13/97 -0500, Chlorine Chemical Council wrote:
>Jon, and the list:
>I sent these postings privately to Jon because he is incorrect to assume that
>the odor of plasticized PVC is vinyl chloride, and out of respect for him I
>did not want to conduct that discussion in public. Clearly, this is now a
>Monitoring done in processing facilities--like those making window
>shades--shows vinyl chloride is always well below the OSHA action level (0.5
>ppm), and usually is non detect at low ppb levels. You can't smell vinyl
>chloride in a processing plant, never mind at home or in your car.
As a result of having to deal with chemical odor issues as part of a review
of a motor vehicle assembly plant proposed permit, I just happen to have
info on my desk on this topic.
Information extracted from "Handbook of Environmental Data on Organic Chemicals"
by Michigan Department of Environmental Quality -- Air Quality Division
indicates the "threshold odor concentration" for vinyl chloride is
4,000 to 25,000 ppm. This is the highest odor threshold listed by far for 6
chlorinated solvents listed. Such gas concentrations are far higher by
orders of magnitude than permissible occupational or environmental
exposures to vinyl chloride. This is definitely a case of what you can't smell
can hurt you if you are exposed to vinyl chloride in the neighborhood of
the occupational health limits.
The boiling point of vinyl chloride is --13 degrees centigrade. It is a
very volatile compound. As a result, any thermal process associated
with "setting" and forming PVC into a product would necessarily drive out any
significant unreacted vinyl chloride monomer that happened to be present,
for a product shape that had a lot of surface area in proportion to its overall
volume (such as venetian blinds or vinyl sheet). This
is why I doubted the claim that the source of vinyl chloride monomer
in landfill gases was outgassing of plastics in those landfills.
As for degradation of PVC into vinyl chloride, I believe that the only
chance of this happening is under a condition of elevated tempertures
high enough to bring PVC into a state of combustion, pyrolisis or thermal
degradation....several hundred degrees..... perhaps also through
UV light degradation at a dramatically lower rate.
The auto plant I'm studying, by the way, has eliminated ALL
chlorinated solvents from the paints it proposes to use.
[TAKE THAT!!!....Chlorine Chemistry Council] [Although they still
use lots of PVC in auto interiors]
That (no chlorinated solvents in newly developed auto plants) sure
wouldn't have been true even 7-8 years ago. Back then, the
auto/Dupont//coatings/Dow Chemical cabal was beating the drum to
exempt methylene chloride from volatile organic compound
rules so it could be substituted unregulated in paint solvents. Since
material has been shown to be carcinogenic, and since
methyl chloroform has been fingered as a ozone layer
depleter, those "auto boys" are back to using poorly studied glycol ethers
with few health effect
studies and poorly characterized petroleum distillates for their paints.
what we don't know won't hurt us and let's just throw
precaution to the wind eh??? ;-> [NOTE to the "humorless"....this last
"deep sarcasm" and not really my position ...so "hold the flames"...]
Alex J. Sagady & Associates Email: firstname.lastname@example.org
Environmental Consulting and Database Systems
PO Box 39 East Lansing, MI 48826-0039
(517) 332-6971 (voice); (517) 332-8987 (fax)