Document pmar6Le6KJ1M4Y48vzzd2ZR7d

DEPARTMENT OF HEALTH. EDUCATION. AND WELFARE PUBLIC HEALTH SERVICE .ONAL CENTER FOR ,7 3 AN AND INDUSTRIAL HEALTH 1014 9ROAOW AY CINCINNATI. OHIO 45202 September 20, 1968 Mr. H. P. Hoopea Product Manager Fibreboard Paper Products Corp, 475 Brannan Street San Francisco, California 94119 Dear Sir: The analysis of air samples collected at your plant in Bneryville, California during our survey in September 1967 has been completed and the results are attached. The impinger samples were counted in accordance with the American Conference of Governmental In dustrial Hygienists method and the membrane filter sample;with the method described in the attached reprint. The present Threshold Limit Value (TLV) for asbestos is 5 million particles per cubic foot (mppcf) as measured by impinger. A tenta tive TLV of 2 mppcf by impinger or 12 fibers longer than 5 microns/ cubic centimeter (f/cc) has been accepted by the TLV Committee. Since the fiber count method is a direct measure of asbestos while the impinger method also measures other, less toxic, dusts, it is assumed that the fiber concentrations are a more relevant index of the workers*exposure hazard. The fiber count limit of 12 fibers longer than 5p/cc was exceeded frequently in mixing, once in finishing, once in packing and in the hopper room. Your cooperation in this study is sincerely appreciated and the data gained from your plant is of considerable value. Sincerely yours. ;J[, Jeremiah R. Lynch S Assist. Chief, Environmental Activities Field Studies Occupational Health Program Attachment