Document rBrogp0921O49Ox1mZgYMKJzG

cmiusMtD not E. I. du Pont de Nemours 51 Company incompohatco Wilmington, Delaware i9898 TEXTILE FIBERS DEPARTMENT cc: c.'. S. Woolard - Cld Hickory C. D. Crook - Old Hickory L _ J. T. Morgan - HatIf*11 I*b. L, Cox i /V ! 7 August 21, r>6) P. J. TRACEY OLD HICKORY 333 ASBESTOS DUST ANALYSIS In aid-1968 we fallowed Coiutructloo Division's lead in adopting an asbestos dust level goal of 0.5 Billion particles per cubic feet (MPPCf). The recognized TLV was then 5*0 (Ref. l) based oo an impinger collection, light* field count technique. We also adopted Construction's proposed nethod of embrace filter sample collection and phase light microscopic analysis as this is more accurate than the iaplnger/light-fieId technique. Cur 0.5 MFPCP goal is only for the snail asbestos particles (less than 5 Bicrons in length) as the recognized Htskel Lab and Construction Safety experts all maintain that the ' ' respiratory systen of the human body can filter out those larger sized particles. In lata 1168 the American Conference of Governmental Industrial Hygeniits published an intent to lower the asbestos TLV to 2 HPPC7 (impinger/light-field count) or 12 fibers per millilcter, greater than 5 >i (membrane filter, phase light mier08copic'Count). (Ref. 2). From Ref. 3. I reduce that the TLV for the membrane filter method excludes the smaller particles to more equate these results with the ispinger method as the lapinger collection efficiency for small partlclc-s is low. I assume ic U from the I.-.63 IL7 intended change that Old Hickory decided to measure only the large asbestos 'iust particles (>5/a) with a goal of 12 particles/KL. iiowever, since tne problem area is ..efiaed today as the aamlL particles ( . 5M-), X suggest that you have a total particle count eade (i.e. 0-5, 5-10,> Up, total asbestos fiber count, and total count for all dust). Also, while the conversion from ML to cubic feet can be readily aade, I think it beat if you would use the MPPCf units so that your results directly cCaspare with our established goal and results from Construction Division and other Textile fibers plants. Dr. Coni, Only, of Pittsburgh, can provide a dust count per the shove slse ranges In tbs MPPCF units - as he new does this for our other plants. HMWfACTURBK DIYI3IC# J. A. Sigmui Division Engineer fay-?yc * -- -- - _' D. D. Druswana DDD:hcs ' Ref .1 Threshold Limit Values - L -67 - Aaericsn Conference of Government Industrial Hygenists. Ref.2 Threshold Limit Values - 1.63 - American Conference of government Industrial Hygenists. . Ref. 3 Measurement of Asbestos Exposure by Lynch tnd Ayer, from Journal of Occupational Medicine, l/6d. 174 SETTER THINGS FOR SETTER LIVING . . THROUGH CHEMISTRY DUP 0901291 SC-DP-02710 Note to J. F. Morgan: In view of apparent discrepancies, could we consider presenting our views on asbestos TLV's, particle size, sampling methods, etc. at the next (5/70) A.C.G.I.H. meeting? This gives us about 8 months to gather data. Suggest we discuss this when Haskell holds the company-wide seminar on asbestos dust hazards. D. DUP 0901292