Document VjvmZEKe89v5MQoXjgyqX2eGj

FILE NAME Talc TALC DATE 1973 Aug 31 DOC TALC456 DOCUMENT DESCRIPTION Memo RE FDA Proposed Talc Regulation . POR Neo RREET e PEERS ADEA TERTDee TAPE 3 Aras atin tte re es . ae Manville Manville Fyhe ; Johns Johns Manville Johns Johns Manville ManvilleManvillMe anvilMlae nville 1. P. A. Martinson 2 West ~ ^<nAhugust 31 1973 9-4-73 From R. S. Lamar R Center Copica Copica Subject Subject FDA PROPOSED TALC REGULATION MORE NUMBER EXERCIZES HOPE FOR REEVES = The FDA regulation calls for talc purities of 99.99 percent and 99.9 percent in terms of chrysotile and tremolite Inspectively Their proposed test method which is completely incompatible with these percent purity data call for maximum counts of 100 for chrysotialned 1,000 for tremolite in 1 mg of talc The FDA test method calls for an optical method of counting at 400X The FDA requirement states further than microns or greater in length and having of 3/1 or greater will be counted only fibers 5 an aspect ratio At a magnification of 400x the lower limit of resolution with an optical microscope using heterochromatic light is 2 x microns In other words no particles below this size would be seen or counted by this method Even at is 5 microns petrographic identification very difficult Positive petrographic identification becomes more possible at 10 microns and above The FDA test requires that a petrographic identification be made ; A most significant point here is that the numbers of particlpeesr unit of weight increases enormously as size of the particles is reduced the In his reporotf August 1973 to R. S. Lamar V. E. Wolkodoff states that M Reeves talc milled Hazen Concentrate 73201-1 contains 6,720,000 particles per milligram by direct microscopic count 500X with the optical microscope it is most likely that the greatest numbers particles below x 2 microns are not seen and not counted This same sample was counted using the Coulter Counter This is a well recognized procedure now used in most if not all hospitals and clinical laboratories for blood counts in place of the older direct microscopic count. 000086 | Page 2 | P. A. Martinson oo August 31 1973 Using the Coulter Counter to count to 1.19 microns we have determined sample has 92,000,000 particles Reeves that 1 73201-1 mg of this down Even at Coulter 1.19 microns lower limit of detectability the Counter is ignoring the greater numbers of particles actually present of calculating the total number of particles of Aanllothseirzeswaydown to the very smallest is to work back mathomatically from the surface mean diameter This was determined by air permeability to be 0.50 microns for Reeves 73201-1 By this method we estimate that mg of this tale contains 554,000,000 particles See memo R. S. Lamar to S. Speil August 29 1973. This number is probably closer to the truth than the other two values ' reported above In V. E. Wolkodoff's memo of August 1973 he reports 504 particles of chrysotile and 336 particles of tremolite in Reeves It is difficublutt very important correct perspective . On the basis of all three counting , as follows to put these data in methods these calculate : Counting Method Total Particles Percent per mg _ Tremolite Optical FDA oe 6,720,000 0.005 Coulter Counter . , 92,000,000 ; 0.00037 -. Surface Mean Diameter by air permeability 554,000,000 0.00006 Percent Chrysotile 0.0075 . 0.0005 = 0.00009 Talc purity by the Counting Method three methods would Percent For Tremolite be as follows Talc Purity For Chrysotile Optical FDA 99.995 | 99.9925 Coulter Counter 99.99963 | 99.9995 Surface Mean Diameter 99.99994 99.99991 000087 HO go RNSR Tee Ie RN RCSA CT ee NOR Se ss Te eee t e ea, . . : aS septic iea erRee egree ER AL IO - See ee S latheen its TREO eee ESS RE eee AR . RRS: wet PREYS ve e sisue. $4 veces Gene gee % Bins Herel RE Page 3 ce | P. A. Martinson August 31 oy 1973 oo Even under the most we FDA are talking 99.9925 percent for This is pretty pure difficult counting procedure optical about purities of 99.995 percent and in tremolite and chrysotRi eel vees material by any rational standard These numbers perspective put this matter in a more rational sane Does < y sanity yet remain in Washington D.C3 7 ; R.S R.S a R. S. Lamar rr CC W. L. VanDerbeek 2 West J. M. Sharratt - 2 West : H. R. Keefe F. L. Pundsack - 2 West D Center S. Speil. D Center : W. C. Streib We D Center R. P. Carter ~ 5 West ; : G. E. Parker - 5 West ; F. J. Solon - 1 West CRMC