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Re: Dioxin Sources

  I'm not sure how much of the recent postings on dioxins sources and
  Greenpeace's recent dioxin report are taking place offlist so pardon me if
  you get this posting twice.
  The two things apparent from the thread are that some list members describe
  reports where dioxin levels (presumeably some type of worldwide cross media
  average) have declined while PVC production has been increasing.  The implied
  conclusion being that PVC production is not related to dioxin levels.
  I have been reading CHEMOSPHERE and have performed my own testing which both
  show a very high emission rate of tetrachlorodibenzofurans from PVC
  pyrolysis.  (Source:  Christmann, W., Kasiske, D., Kloppel, K., Partscht, H.,
  and Rotard, W.  combustion of polyvinylchloride - an important source for the
  formation of PCDD/PCDF.  Chemosphere 19 (1-6): 387-392 (1989))
  One might say that PVC doesn't cause increases in worldwide dioxin levels
  directly, linearly, and all by itself.  This would lead many observers to
  neglect PVCs enormous contribution of nealry equally toxic polychlorinated
  dibenzo furans.
  There are many other variables in the equation such as cement kiln operators,
  secondary metal smelters, changes in how detection limits are factored into
  mass balances, changes in methods and in the detection limits themselves.
  My request to scientists of all political stripes is:
  I apologize for being obtuse and for shouting, but the people who do this
  know exactly what I am talking about.  Those of us with the priviledge of
  specialized knowledge which was given to us with great public subsidy must
  remember to use that knowledge to inform, and not to confuse or propagandize
  the public.  To do otherwise is to bite the hand which feeds us.
  In closing those who wish to know more about the context of Greenpeace's
  report can consult the following papers:
  Exploring the Balance between Sources, Deposition, and the Environmental
  Burden of PCDD/Fs in the U.K. Terrestrial Environment: An Aid To Identifying
  Uncertainties and Research Needs , Environ. Sci.
  Technol.<VOL>31<ISS>1,11,ESTHAg,<ISSN>S0013-936X(96)00121-6, Copyright; 1996
  by the American Chemical Society
  Dioxins in the Environment: A Review of Trend Data ,Environ. Sci.
  Technol.<VOL>30,<ISS>11,<SPN>3133-3143, ESTHAg,<ISSN>0013-936X, Copyright;
  1996 by the American Chemical Society, R. E. Alcock and< K. C. Jones,
  Institute of Environmental and Biological Sciences, Lancaster
  University,Lancaster, LA1 4YQ, U.K., Received: April 8, 1996