Document LgLXaJZQxQMx1XQqy8nGQa597

FILE NAME Talc TALC DATE 1970 DOC TALC409 DOCUMENT DESCRIPTION Unpublished Internal Report - Talc Fibrous - Tremolite ge TALO FIBROUS - TREMOLITE 5 fibers ml > 5 min length variety The fibrous of talc as well as that of its associated amphiboles tremolite and anthophyllite anthophyllite contain fibers which are classi- fied as asbestos Fibrous cale has been shown tobe of greater physio- | logical significance than the non fibrous variety in a number of environ- related and clinical studies to workers exposed totalc dusts A mental mineral differentiation proper evaluation of the dust hazard requires a values in the threshold limit for the fibrous and fibrous forms 1 Porro ' Patton and Hobbs on the basis of 15 cases with 5 post- _ mortemexaminations reported that asbeosftottiaclcboosdiisesanadrenoatlemdosatdeignrveareiaobfly present in the fibrotic areas in cases " similarity between asbestosis and pneumoconiosis due to talc Siegal and associates 2 found an advanced fibrosis incidence rate of 14.5 14.5 per cent | Inastudy covering 221 tremolite talc miners and millers The dust to which these workers were exposed was largelyfibrous andthis physical characteristic was considered tobe responsible for thepathology of the lung lesion particularly because ofits resemblance tto oasbestosia Findings by McLaughlin and coworkers 3 indicated that tale pneumoconiosis , could he caused only by the fibrous varieties of talc Asbestos was con- sidered , be more actively fibrogenic possibly due to the higher propor- tionof fibers in asbestos In postmortem examinations on 8 talo industry workers Schepers and Durkan 4 found histological featureswhich suggested a 000109 ee TALO 2. cromolite characteristic that a was the main pathogenic agent i provoking the There teaction talc lung lesion might cause a animal degree talc dust on was reason to suspect that the fibrous of the asbestotic type In studying the tissue -the same authors 5 found that the , amphiboles of effects to rather which the fibrosis supervenes depends on the length of the fibers than on their chemical composition Kleinfeld et al 6 reported postmortem 2 findings on 6 talc industry workers in which thebodies found in respiratory when 2 bronchioles or imbedded in fibroustissue were indistinguishable from asbestos Engine when when bodies as seen in asbestosis Engine Because of the striking similarity in the fibrotic reaction produced = by talc and asbestos fibers the suggested thresholdlimit of 5 fibers exceeding 5 microns in length per milliliter of air. 18 recomma ended for | talc References Roentgenol Greenburg 1. Porro F.W.Patton J.R. Hobbs A.A Am J. Roentgenol 47 507 1942 2. Siegal W.Smith A.R. .: Am J. 49 11 1943 A.I.G. E. Dunham K.C Drit Ind J. Med 6 184 . McLaughlin Durkan 1955 McLaughlin T.M 3. Rogers 4. Schepers G.W.H.G.W.H. Arch Ind Hith 12182 C.P. 5 ibid Arch Ind Hlth 12 317 1355 6. Kleinfald M. Ciel SS.F. .F. Messite .: Arch Environ Majeranowski Ss ee Hich % 101 1963 z t x ok TALC 000110