Document 2jJvJ713Bj8VmwQ9aoN6Exa6R

FILE NAME Manville JMA DATE 1965-1973 DOC JMA242 DOCUMENT DESCRIPTION Letter & Memo - Threshold Limit Value BO GHQ March 3 1965 W. L. VanDerbeek Toledo Threshold Limits Each year the American Conference of Governmental Hygienists meet to set maximum allowable concentrations for various dusts fumes vapors noise etc. A given substance is first put on a tentative concentration list and after some time elapses if there is no objections from industry the material is given a permanent rating Last year fiber glass was given a tentative maximum allowable concentration which would make it appear much more hazardous than silica We have objected strenuously to this and I have met with representatives of Corning and Pittsburgh Plate Glass on the subject The new chairman of the committee on these maximum allowable concentrations is Dr. Paul Gross Research Pathologist at the Industrial Hygiene Foundation in Pittsburgh As you know he is a good friend of Manville and has done excellent work for us for many years Unfortunately he has no knowledge whatsoever of the fiber glass industry I would like to have your permission to invite Dr. Gross to visit our Defiance and Waterville Plants on March 25. He already made arrangements to visit the Corning Plant and Research Center in Toledo If this permission is granted Cliff Sheckler will accompany Dr. Gross on his indoctrination tour March 25. We can make further definite travel arrangements with the plant managers if you concur Kenneth W. Smith M.D. 7439 Manville Corporation Greenwood Plaza , Denver Colorado 80217 Environmental Affairs Department : contentacontentacontenta contenta Afess Afess . contenta . re) ae May 7 1973 Dr. Herbert E. Stokinger U. S. Department of Health Education & Welfare Public Health Service National Institute for Safety andHealth Occupational 1C0i1n4ciBnrnoaatdiwayOhio Ohio4520: 2 ) Dear Dr. Stokinger It is my understanding that you still hold the position of Chairman of the Threshold Limit Value Committee of ACGIH and this letter is addressed to you in that capacity The scientist in charge of our diatomaceous earth and talc research has called to our attention that the definition of TALC Fibrous as it appears in the Third 1971 of Documentation of the Threshold Limit Substances in Workroom Air is in error Edition Values for On page 243 reference is made to the fibrous variety of talc The pure talc mineral is never fibrous but is platey or micaceous Pure talc does occur in nature but more often with a number of mineral contaminants such as calcite dolomite quartz serpentine magnitite magnesite chlorite and in some cases the asbestiform minerals tremolite chrysotile and anthophyllite The pure talc mineral can appear fibrous when examined by light microscopy However the fibrous appearing material is actually rolled platelets or platelets on edge or at an angle In our opinion the documentation for TALC Fibrous should be rewritten to eliminate any reference to fibrous talc and instead should refer to the fact that talc ores can contain fibrous contaminants which are asbestiform minerals - Dr.Herbert E. - Page 2 May 7 1973ep^/rastrukt 1973ep^/rastrukt Stokinger W. B. Reitze and I would discuss this with you at later this month conference appreciate the opportunity to the AIHA in Boston Very truly yours JOHNS -MANVILLE CORPORATION " Edmund M. Fenner Director Technical Relations EMF ow. oot, ; Sa Boo Lt MIN De ld