Document 2qM7vG9NrLeJveq1bJ56ob4xr

.;*4M <jp 4U4. >f . -- 4<ut Cf t : CK rmrn* fM< * Orw***'*^' W*V 4 i. ***** *< w *10>iW---^m**-. Amn u i. ftAlltf. *Ml C*e---we** / 0iw * > > >WWHy`i4 17 U0 . 871137 *0 ). HOSIT, VWl Ow.-** v Oc<x-- * !'* 4 MNi* L ***** NmW Wv*i .. MIritM- wwna. nC*t****i. 0M (US OWAIO I. AYfR. V<a aimer -r**w # 'Ckimi iafey 4 Nmmlt* \ *w*4* mn* krv<i *lurw-*ii>tvm. m O*** 4UB . AFRICAN CONFERENCE T^m *. 0AV14 GOVERNMENTAL INDUSTRIAL HYGIENISTS DMWnOM l. VAUOHAM *. O. *mm Vm Dr. Richard Henderson Olin-Mathieaoo Chemical Corporation 275 Winchester Avenue New Haven, Connecticut 06504 011-1970-00004082 nnminiuiiiiiiHniflDHHi Dear Dick: Regarding jour concern over Che TLV for VQTL CHLORIDE, I can't blame you. Follow ing jour call, I looked up the file on the Documentation for the TLV and found that it had been revised in 1962, following the report bj Torfcalaon et al, AIHAJ, Oct. 1961, to 50 ppm. Why this limit was never published in the TLV booklet was the result of a subsequent publication by Lester et al, AIHAJ, 24. 265, 19^5 that disagreed with the Dow investigators and reported evidence for the suitability of the 500 ppm limit. Despite a great deal of discussion with both groups, no reconciliation between the discrepancies was forthcoming, and there the matter lay. I note, however, that Stewart, AIHAJ, 30, 537* ^9^9$ evidently goes along with the 500 ppm limit, as this was one of the levels to which he exposed human volunteers repeatedly. Also, noted in the seme article (Fig. 6), Vinyl Chloride concentra tions were coexnonly as high as 200 ppm on some of the work shifts apparently in Dow Chemical's plants. - Speaking for myself, and not as a statement from the TLV Coaanittee, I would think f that a concentration not much in excess of 200 ppm should be a suitable limit on the basis that Dow Chemical's operating staff keep a pretty close watch on such matters, and if 200 ppm were too high, they would have reduced it in accordance J with their supposed animal findings. This I derived from a rather thorough discussion with the medical and environmental aspects of Vinyl Chloride workers at Dow Chemical Plant (Drs. Kramer, M.D. and Mutchler, Fh.D.) at the Gordon Conference in 1968. These individuals reported 25 years experience with Vinyl Chloride workers. Hundreds of thousands of air samples were taken over this period of time, and since 1939* continuous sasqpling was instituted, as well as breath analyses of the workers. The mean air concentra tion between 1950 and 1967 was 160 ppm, many of the values being well below 50 ppm. There was one maximum peak at 600 ppm. Selection of a suitable TLV is clouded by the fact that exposures to Dow Chemical's Vinyl Chloride are also to about 5 PP of VINYLIDENE CHLORIDE at these levels. Sunanary data from Dow indicate fairly high toxicity of this substance, see enclosure. Putting all of this information together, along with the '69 paper of Stewart, I would think that a TLV with a 200 ppm ceiling would be about as much as we should recommend. However, we will leave this matter up to the TLV Coiittee, which is meeting soon. cc: Elkins, Grabois, Smith, Knauber, Caplan "~%r Herbert1V.^Jcok^ngsr, OU 1557