Document 6B4LqD3BRJR9Q5b1Rrr3kKrb9

LESTER 7. CRALLBY PITTSBURGH Pebwtry 27, 1962 I MR. F. H. REGBHR VERROH MORES 6 Ret SAWING KARANITS In view of the analysis of the above product, we certainly agree that a threshold Unit value for a waigbted 8-hoar repeated daily exposure would be 5 MPPCP. . - One of the things we are anxious to avoid, though, is aisinterpretation of the aeanlng of threshold Unit values for pneueoconiosis-prodaclng dusts. Certainly, atnospherie levels of 2 to 3 tines the threshold Unit value for re peated daily exposures of 1 to.2 hours would be well within the interpretation of this Unit provided the individual is not exposed to significant atnospherie levels of other pnccnoeoniosis-produeing dusts during the day. LVCtDB ces T.I.McClintock - Vernon P.R.Powell - Ternon W.H.Sharp - Vernon -^T.B.Bonney, file L. V. Cralley ARCH 19181 i