Document 3eRZmgLD5K0d7B7O6eX6B84O6

, - General Chemical Division > VI"1 gMEMKAL C0WOSA7.0N ** V/ vV * ') /- VINYL CHLORIDE - TOXICITY MEETING OF AM. IND. HYG. ASSOCIATION WAsHtNGf6F. b.C. - "may 13-17.19EZ Technical Director Mr. J. C. Fedoruk W. A. Knapp May 28, 1962 1. Pursuant to our recent conversation, the writer attended Thursday afternoon session of subject meeting to hear paper by Dr. David Lester of Yale. This paper reported our results with vinyl chloride which are in sharp contrast to those reported by Torkelson, Oyen and Rowe of Dow Chemical in the INDUSTRIAL HYGIENE JOURNAL, October 1961, pgs. 354-361. 2. In the Dow study the animals (albino rats) were exposed to a maximum concentration of 500 ppm for 4-1/2 months; in our study animals were exposed to 20,000 ppm for 3 months in longest exposure test. Dow reported patho logical changes in liver and kidneys, we found only morphological alterations and nothing that could be described as pathological change. Although our study was not as long, the exposure concentration was 40 times their level and injury would have been expected to be much more severe. 3. In view of conflicting results Dr. Lester went to great pains to describe a "double blind" procedure to examine tissues microscopically. Reason for the different result remains unexplained but sufficient doubt has been cast on validity of Dow results so that it is unlikely that present threshold limit value of 500 ppm will be reduced to 100 ppm (or weighted average of 50 ppm) recommended by Dow. Dr., Herbert Stokinger of U.S. Public Health Service and chair man of the ACGIH committee on threshold limit values sat with us and discussed Dr. Lester's paper after presentation; he will recommend continuation of the present value. 4. Other than differences in pathologist's findings which are not uncommon, the only conceivable reason for different results is possible impurities in Dow material. In their article they analyzed their product via gas phase which could reasonably miss liquid phase impurities. ASI 000015758 General Chemical Oiv IN -OWOLA.V. Hr. J* C* Fadoruk -2 5/28/1962 5. The maintenance of a reasonable threshold limit value for vinyl chloride la important in our development of this material as an aerosol propellant* research Consultant CC: SS* Ge^etron Saies ?1gr. ,ih**F.C.Hitehing3, Attn IYO. Safety Manager, Hr. J. Guelich A.Wallace Tech.Serv.,Mr. W. B. Sherry CCRL. Safety Supv., Hr.R.D.Poirier Solvay, Org,Sales,%r., Hr, R.A.Marshall Solvay,Moundsville Wka. ,Mgr. ,Mr.P.B. Cornell Solvay, Syracuse, Org.Prod..Toch.Serv.,Supv.,Mr.W.G.Dooley AS I 000015759