Document b5oR3wM4MGQRyxVjavJQLr2QD

.C-RS M E M O R A N D U M ,#A1L Subject: June ?5, 1977 E. Ccllerd, V. Griffin TSA FCG Garden State "Cyprus Riston Vapor T a l c R Samples # ' s 74-77) 6 2 7 - 7 6 OGS file 4 FJS n rht HBW PJH \ : D . G. 5. &UG 1 ( 1' i U 60 In recent months, various. stGi?0s by QiPi&iGftjfjal Institute for Occupational Safety and Health (NIOSH) , National Bureau of Standards (KBS), Occupational Safety and Health Adninistration (OSHA) and Bureau of Kines have questioned the technique of using phase contrast microscopy to perform asbestos fiber determinations. In particular, talc samples have caused considerable controversy because of the difficulties they present to an analyst in separating or defining the various types of asbesto3-form fibers that may be present in many talc products. The Travelers Chemical and Environmental Laboratory has been aware of the controversial aspects of the phase contrast microscopy technique and has attempted to make rational and accurate decisions in d e t e m i n g if samples being analyzed do contain asbestos fibers. Kvc*n though various precautions are taken for the analysis of asbestos fibers, it has been our concern, particularly with talc, that the standard method of phase contrast microscopy may not be adequate. To investigate the variability resulting from the phase contrast microscopic technique, the Chemical and Enviro/miental laboratory performed a study on several samples that had been previously analyzed using the standard phase contrast microscopic method. All the samples in the study were bulk samples and were previously reported to positively contain asbestos-form fibers. Also, all the samples with the exception of one v/ere talc samples that had been submitted to determine if they wei'e asbestos-form talc. The samples were analyzed by using a combination Scanning Electron Microscope (SeM), Transmission Electron Microscope (TEH), Energy Dispersive Analysis of X-Hays (KUAX) and Selected Area Electron Diffraction (SARD). Samples of Cyprus Industrial Minerals Companies Kiston Vapor Talc wore analyzed by using these more sensitive methods and no asbestos-form fibers could bo found in the samples. All the particles that were previously considered fibers, when chocked at higher magoificiation, were reflections of talc platelets. Approximately fifty thousand particles were examined from these talc samples. Tills indicates there is a 95# probability that the fiber content of these camples is less than 0,01#. >it6 any. j-7S r>i,KD.s.i EXHIBIT CAM-378 S W Goodhue 000251 I examined these samples on two different occasions, first at a vendor laboratory where an analysis was performed using n SEK and TEX-EDAX-SAED systems. Then, at the invitation of the Cyprus Industrial Minerals Company, I went to their Los Angeles laboratory and analyzed the samples a second time using their SEM and TEK-SAED systems. I would like to thank 0. Gill and C, J, Palmateer of the Cyprus Industrial Mineral Company for their cooperation in these studies, The Chemical and' Environmental Laboratory v?as not able to confirm its original findings of asbestos-form fibers. Wc also acknowledge because of the limitations of the standardized phase contrast microscopic technique that the original findings were not an accurate indication of any fibers in the product. The preceeding results reflect "the findings of a laboratory study. They may not be used for or are considered to-be a specific product endorsement. RH'Ic/ekm X 'il'd i Ronald E. KcCullcn lob Administrator