Document r0e1G6Ryewp3mYB7GMZkqBxr

MEMORANDUM DEPARTMENT OF HEALTH, EDUCATION, AN D WE L FARE PUBLIC HEALTH SERVICE FOOD AND DRUG ADMINISTRATION TO : DIVISION OF COSMETICS TECHNOLOGY PRODUCT COMPOSITION BRANCH ATTENTION: RONALD L. YATES " DATE: December 2, 1976 FROM Acting Director, Science Branch (HER-2loXl) SUBJECT: Asbestos In Talc / Analysis has been completed on /thebeight samples that you forwarded with your Octobef4 5, 1976'm^mo. Four of the samples were found to contain chrysotile, four were found to contain tremolite. The Nomarski Differential Interference Contrast microscope was found to be useful for the detection of chrysotile fibers in talc. A chrysotile count was made on the four samples found to contain that type of fiber. Analyst Leonora Auerbach's report on her examination of these samples is enclosed. A copy of Ms. Auerbach's paper on the optical microscopic detection of asbestos in parenterals is also enclosed. This paper has been accepted for publication in the March issue of the JAOAC. We would appreciate hearing how our results compared with those obtained by other methods. V TED M. TMH:bh 7 (b) (5) MEMORANDUM DEPARTMENT OF HEALTH, EDUCATION, A N D W E LFARE PUBLIC HEALTH SERVICE FOOD AND DRUG ADMINISTRATION TO GEORGE H. BOONE DIRECTOR, SCIENCE B R A N TM rv THRU: TED M. HOPES CHIEF CHEMISTRY SECTI d a t e : November 23, 1976 fr o m : Leonora Auerbach Chemist, Lab H s u b j e c t : Results Of Survey Of Chrysotile And Tremolite Asbestos In Talc. Introducti on: This memorandum reports on the application of the Nomarski Differential Interference Contrast microscopical system (NDIC) for the qualitative and quantitative analysis of chrysotile and tremolite in talc. A pre-publication copy* of the paper "Use Of Three Optical Systems To Obtain A Microscopic profile Of Asbestos And Other Non-Opaque Particulates Larger Than 5 Micrometers In Parenteral Drugs" is attached. The microscopic equipment used for analysis is described on page 3 of the paper. It was determined that the NDIC has no application for the detection and quantitation of tremolite in talc, but the NDIC is very useful for the detection and quantitation of chrysotile fibers in talc. Chrysotile fibers not visible in the crossed polar mode in plane polarized light are visible in the NDIC. Chrysotile is recognized by its characteristic fibrous morphology. The enclosed photo of Canadian chrysotile (photographed at 200X)in refractive index oil 1.464 illustrates the sharp image visible in the NDIC system. *JA0AC, 1977, 60, March. -2- Quali tative: The qualitative procedure used consisted of mounting sample crystals in refractive index oils 1.464 and 1.590. The 1.464 mount was examined at 500X using the NDIC, and the 1.590 mount was examined in plane polarized light at 500X. Crystals in the 1.590 mount which exhibited inclined extinction, positive elongation, and had a higher refractive index than the oil in both extinction positions were called tremolite particles. Wavy, cylindrical fibers visible in the NDIC in the 1.464 mount were called chrysotile fibers. The talc samples examined were known to contain either chrysotile or tremoli te. Results: DOST 77-1371: chrysotile present. DOST 77-1372: chrysotile present. DOST 77-1373: chrysotile present. DOST 77-1374: chrysotile present. DOST 77-1375: tremolite present. DOST 77-1383: tremolite present. DOST 77-1384: tremolite present. DOST 77-1385: tremolite present. Quanti tati ve: The quantitative procedure employed for the chrysotile count was as follows: 0.5 mg + (0.030 mg) of sample was carefully mixed in a drop of 1.464 Cargille refractive index oil and evenly distributed under a 22 X 22 mm coverslip. The preparation was examined at 500X using the NDIC optical system. A field by field count was made until 150 fibers were counted or 1/10 of the cover glass area was examined. 3- - The number of fibers per 0.5 mg was calculated as follows; No. of fibers per 0.5 mg = No. of fibers counted x cover glass area No. of fields counted x microscopic field area Results: DOST 77-1371: found 4,267chrysotile fibers per 0.5 mg DOST 77-1372: found 1,943 chrysotile fibers per 0.5 mg DOST 77-1373: found 760 chrysotile fibers per 0.5 mg DOST 77-1374: found 1800 chrysotile fibers per 0.5 mg Comment : The NDIC system has application for the detection of chrysotile fibers when used with plane polarized light microscopy. We would appreciate receiving information concerning the con centration of chrysotile and tremolite in the samples. *,/*.'/u Cuut/^<-<vL' LEONORA AUERBACH