Re: Vinyl chloride odor

[asagady@sojourn.com]

  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
  >public discussion.
  >
  >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,
  particularly 
  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
  methylene chloride
  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.
  But hey,
  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
  comment is 
  "deep sarcasm"  and not really my position ...so "hold the flames"...]
  
  
  
  *
  
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