Document pXpxyqz9xjx4y5RD1VQDK4ND

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 - HaikeLI lab. L, Cox i /V ! / August 21, r"i6) P. J. TRACEY OLD HICKORY ASBESTOS DUST ANALYSIS In aid-1968 we fallowed Construction Division's lead in adopting an asbestos dust levs1 goal of 0.5 Billion particles per cubic feet (MPPCT). The recognized TLV was then 5*0 (Ref. l) based on an impinger collection, light* field count technique. We also adopted Construction's proposed nethod of aembrane filter sample collection and phaae light microscopic analysis as this is more accurate than the impinger/light-fieId technique. Our 0.5 MFPCF goal ia only for the email asbestos particles (less than 5 microns in length) as the recognized Haskei Lab and Construction Safety experts all maintain that the ' respiratory system of the human body can filter out those larger sized particles. In late i~<68 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 milLLlcter, greater than 5 p, (membrane filter, phaae light miero8copic "bount). (Kef. 2). Prom Kef. 3. I reduce that the TLV for the membrane filter method excludes the smaller particles to more equate these results with the impinger method as the impinger collection efficiency for snail partlcic-s is low. I assume ic i.3 from the 1.-63 IL7 intended change that Old Hickory decided to measure only the large asbestos 'iust particles (>5/i) with a goal of 12 part ides/ML. iiowever, since tne problem area is refined today as the small particles ( 5p), I suggest that you have a total particle count made (i.e. 0-?, 5-10, >- liji, total asbestos fiber count, and total count for all dust). Also, while the convertioa frost ML to cubic feat can be readily made, I think it beat if you would use the MFFCF units so that your results directly compare with our established goal and results from Construction Division and other Textile Fibers plants. Dr. Coni, Unlv. of Pittsburgh, can provide a dust count per the above alma ranges in tbs MFFC7 units - as he new does this for our other plants. MAWFACTUBX9S DIYI3IC# J. A. Slgman Division Engineer by ------- -- --^ D. D. Orusmond DDD:hcs Kef .1 Threshold Limit Values - L -67 - American Conference of Government Industrial tygenists. Ref .2 Threshold Limit Values - l .<53 - American Conference of government Industrial Hygenists. Ref. 3 Measurement of Asbestos Exposure by Lynch sad Ayer, from Journal of Occupational Medicine, l/f>3. 174 SETTER THINGS FOR SETTER LIVING . . THROUGH CHKMISTttY DUP 0901291 SC-DP-02710