Document YjMBX4p23zn2a2ooJOqGnOQky

1STA/ NATIONAL CENTEN EON unban and inoustnial health 1014 BNOAOHAV CINdNHATI, OHIO 4M02 DEPARTMENT O.F HEALTH. EDUCATION. AND WELFARE PUBLIC HEALTH SERVICE ' January 18, 1968 / 7 I REFER TO: Mr. Peter Kostlc Dewey and Almy Division i I V. R. Grace Company Cambridge, Massachusetts Dear Mr. Kostic: Enclosed are the results of the fiber counts made on samples collected at your plant in Libby, Montana. These counts were made at 430X magnification under phase contrast illumination using a method ve developed for use in our epidemiological study of the asbestos products industry. An equivalence between this method and the impinger which we developed from ashestos study data leads us to believe that fiber concentra tions of about 50 total fibers/cc or 30 fibers/cc greater than 5 ji are near the present TLV. As you can see these concentra tions are exceedsby all but one sample and it appears likely that a hazardous asbestos exposure does exist. In addition, our current TLV may well be too high and if the British TLV of 2 fibers/cc greater than 5 ji were applied, the dust concentrations are from 10 to 100 times in excess of the safe limit. I have discussed this matter with our Salt Lake City field station and 1 am sure they would be happy to honor a request for assistance in developing a control program submitted via the Montana Department of Health. If I can be of any further assistance, please let me know. Sincerely yours, f Enclosure wn fj Jeremiah R. Lynch ) J Asst. Chief, Environmental Activities Field Studies Occupational Health Program 15162476 0M9G0S& Results of fiber counts on membrane filter general air sauries collected at the Zonollte Division, W. R. Grace Co., Libby, Montana, on February 1, 1967. Location Second floor Fifth floor Sixth floor Fibers/cc Total Fibers 75 ii fibers 280 110 40 21 93 71 310 200 140 50 54 33 300 210 15162477 *