Document VJeY6wdxmLaQa4LjopxjN1Lv4

PLAINTIFF'S EXHIBIT PUP-257 . IlilMMIW# E. I. du Pont oc Nemours 5 Company MffMRun# OLO HlCKOtlY, TcnnCSSCC 37IM CC: J. S. Crawley C. H. Lueck J. J. Perkins E . S . Woolard D. D. Drummond, WILMINGTON J. A. Sigman (2), wilhimgtcn TEXTlLt 71 OCAS OtFAWTMCNT PDRSC'K'AL ACT CON"IDENTIAL Old Hickory, ' lenr.es see October 2, 1969 _______ RECEIVED >\ P. Morgan Haskel Laboratory WILMINGTON . **;<:.. .aECHa'Cx METHOD OF REPORTING ASBESTOS DUST LEVELS Ref.: (1) Telacon: c. D. drook and J. P. Morgan, same subject, 9/11/69 (2) Latter: D. D. Drummond to P. J. Tracey, "Asbestos Dust 'Analysis,* 8/21/69 (3) Private communication with Jeremiah R. Lynch, Bureau of Occupational Safety and Health, U. S. Public Health Service, 1014 Broadway, Cincinnati, Ohio (4) Threshold Limit Values for 1968, American Conference of Industrial Hygients, St. Louis, Missouri (5) R. J. Blair to 0. W. Hess, "Asbestos Exposure Hazards," 8/16/6 8 Per reference (1 , I have formalized what I believe is true about re porting asbestos dust lsvsl and request your opinion by return letter. Cur eventual agreement will determine how asbestos dust level will be reported witnin the Taxtile fibers Department. Please comment concerning the following two items: 1. The best method to report asbestos dust level is fibers per milliliter longer than S microns in length. . 2. Construction Division's adoption (Ref. 2) of an asbestos dust level of 0.5 million fibers per cubic foot less than 5 microns in length. This may be questionable for two reasons: Zt ignores the long fibers which ara known to enter the lung - and cause asbestosis. o It applies a numerical tclerancs value intended for overall dustiness (fibers plus grains) as measured by the impinger method to fiber aujtnosx (grains not counted) as measured by the membrane filter method. As a rssult their tolerance value is above that recommended by the U. S. Public Health Service . (Raf. 3) and the American Conference of Governmental Industrial Hygients (Ref. 4). 17C oCTTcn things ro* nrrrrrt living .. rrn*auoa cuLttisrmr DU* 0901308 j. P. Morgan 2 October 2, 1969 T>TSOUS SION ' It bis been established that long fiber do eater the lung tad cause asbestosis. Therefore, the concentration of long airborne fibers Bust be' controlled (see Attaehaents I, II, and III). It is not known if short fibers ~ause asbestosis. Some studies allow short fibers to be inert (Attachment IV) ; others indicate they could be as harmful as long fibers (Attachment V). The U. S. Public Health Service does not consider short fibers inert but maintains that if the long fiber level is low, then the short fiber level will be low also (Ref. 3). Reference 5 specifies that 0.5 million particles per cubic foot to be used as a tentative tolerance.,, This was obtained by taking one-tenth of official governmental standard. But the governmental standard is for overall dustiness (fiber plus grains). Obviously, applying the same numerical value to fibers only gives a high tolerance value: 0.5 million fibers per cubic foot is equivalent to 18 fibers per milliliter; the governmental standard for fibers is 12 per milliliter. To avoid con fusion in the future, I recommend that we always talk in terms of fibers per milliliter. v. ' DACRON* MANUFACTURING DIVISION J. K. SNEED PROCESS SUPERINTENDENT CDC :dd Attaclunar.tc CHARIES D. CROOK DUP 0901309