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FILE NAME Threshold Limit Values TLV DATE 1966 DOC TLV006 DOCUMENT DESCRIPTION Documentation of Threshold Limit Values Committee on Threshold Limit Values +t Osa S067 fee 4A0T are addt 4dd0 4dA44 Shi aa+s Cte 44s CSS 0447 Oe? aseet ashi Sts alte 444d 40 Aad L0Ct ets aaa 4707 sas 44hs CL4F 4Aht CTE COLE carer ath? se eats ^'4s/ atte athe . Documentation tIth 44s Documentation ortt were Stes a ane Documentation +77 art 477s Sere Cese eats Sts 7Ote 74+ ete ares C477 LAhs Late attr S^'ee Limit Limit thhe eR Ag rat LOST Sti seco Cts ts the Threshold Threshold 4s 44h 4s "Lhe TIGL Seer cass 4Iss CA4G 6400 tthe *ShE hots "4hhe 44s shthe GIST Stbe 4444 cAts F+th COs AAA e "StL thle LIGs *AOhe tA Le A470 AdP7 thhbe Sth, 44st OOF 440F SOTe c4OEE ffde 2444 aI4As 400E see 4404 eaee A ses thle thle eer Pere thie Sthe 44S stle AAA 4247 see fhe hse 404t COG bee Ce, SEOLOEPPEPLLEOEELDLEDEDOIOOBOLL A VOOODOADATIOAGGOOTPOOELROPIEOLTEPRPEOTPDOLIEIIALESEOE . 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SOLE Ltt LCs Ltt 70te STPA 44rd. reae aire esse EDITION REVISED EDITION atnr ne e COE nee VY c4he rare Lae sets aehe Cts Shee atts see POs tse CCFC ate cart 2Aaee shee tee OLE hte atts Sade F444 yd Shh ashe Asis S97: 44h? S44. seer thee 4eet SPI esses sts Yor L208 C044 COMMITTEE ON THRESHOLD LIMIT . VALUES VALUES eae Pods 349 wit tle sae ere aere 3234 Lee LAT EAA ares cere te ae cere eee i et ee, Copies of this publication may be obtained from American Secretariry er Conference of Governmental Industrial 1014 Broadwa Cincinnati Ohio 45202 Hygienists Price per copy 9.50 Make checks payable to American Corerence Corerence of Governmental Industrial Hygier sts Copyright 1965 by American Conference of Governmental Industrial Hygienists 11 a References =< 1 Henderson Henderson 1943 Y. Haggard eee H.W ee Noxious Gases Reinhold Publishing Co. N.Y. rani, Nau C.A South Med J. 41 341 1948 jm^/ Elkins H.B Chemistry ofIndustrial Toxicology Wiley & Sons N.Y. 1959 jm^/ Bulmer F.M.R. et .: J. Ind Hyg & Tox 22 111 1940 jm^/ ASBESTOS ne 5 mppcf Asbestos is a generic term applying to a number of mineral silicates that are incombustible in air and can be separated into filaments The most widely used in industry is chrysotile a magnesium silicate from serpentine Other types include amosite an iron magnesium silicate crocidolite a sodium iron silicate tremolite a calcium magnesium silicate and anthophyllite also an iron magnesium silicate Miller and Sayers 1 showed that intraperitoneal injection of amosite chrysotile and crocidolite in guinea pigs produced the reaction of an inert dust Vorwald et al 2 confirmed this for short fibers under 3 but observed that long fibers produced a fibrous reaction Continuing unpublished work by Gardner these workers demonstrated that long fibers 20 microns and above produced peribronchiolar fibrosis in lower animals and developed evidence that thi resulted from mechanical rather than chemical action Asbestos dust containing 0.0 per cent fibers longer than 10 microns in concentrations of 138 mppcf or 0.8 1lion long fibers per cu ft was capable of producing experimental asbestosis n guinea pigs When the concentration was 6.7 per cent fibers over 10 microns 40 mppcf equivalent to 2.7 million long fibers per cu ft the reaction developed in approximately approximately half the time That exposure to asbestos is associated with cevelopment of a potentially dis- 3,4,5,6,7,8,9,10,1 abling pneumoconiosis in man has been amply demonstrated by industrial experience 3,4,5,6,73,,48,,5,96,,7,18,09,,101,111 The present threshold limit was recommended by Dreessen et al 8 after study of 541 employees in three astestos textile plants using chrysotile Only three doubtful cases of pneumoconiosis were found in those exposed to dust concentrations under 5 mppcf whereas numerous marked cases were found above 5 mppcf Counts were from impinger collected samples in ethyl alcohol and distilled water Both fibrous and nonfibrous particle were counted but the latter greatly predominated While chemical analyses of c llected samples of borne dust corresponded to those of settled dust samples it is believed that dust counts of particulates by conventional methods can be expect d to give only an indirect measure of the risk of asbestosis because of the great rel tive importance of long fibers References 1. inim inim fu 5 br^, br^, br^, g 10. 11. Miller J.W. Sayers R.R Pub Health Rep 56 264 1941 Vorwald A.J. Durkan T.M. Pratt P.C Arch Ind Hyg 3 1 1951 Merewether E.R.A J. Ind Hyg 12 198-239 1930 Pneumoconiosis Abstracts 1926-1938 Vol I p 128 Wood W.B. Gloyne S.R Lancet Dec. 22 19. Fulton W.B. Dooley A. Matthews J.L. Hou z pp 1383-1385 R.L Penn Dept. Labor and Ind Bull 42 1935 Lanza A.J. McConnell W.J. Fehnel J.W P.b. Health Rep 50 1 1935 Donnelly .: J. Ind Hyg & Tox 18 222 1136 Dreessen W.C. DallaValle J.W. Edwards T.i. Miller J.W. Sayers R.R Pub Health Bull No. 241 Washington D.C. 1938 Lynch .: Arch Ind Health 11 185 1955 Smith K.W Arch Ind Health 12 198 1955 Cartier .: Arch Ind Health 11 204 1955 15