Document bObaZGkOqd8gJoGR31JDwpEGk

FILE NAME Corning OC DATE 1964 Apr 22 DOC OC123 DOCUMENT DESCRIPTION Memo RE Selikoff Article - Asbestos Exposure and Neoplasia F. H. Edwards W. C. Taylor oo. ASBESTOS EXPOSURE AND NEOPLASIA SELIKOFF ET AL JAMA APRIL 6 1964 April 22 1964 8. . W. Grant Pfeifer At your request we have studied the subject article particularly in the light of its possible application to Kaylo It is noted that the authors state neoplasis associated with with asbestosis seldom occurs until 20 years after first exposure to asbestos asbestos limit dust Therefore we decided to such an exposure history the present analysis to men with The cases under study were the 632 insulation workers who entered the trade before 1943. Of these 632 men 339 had been exposed to asbestos dust prior to 1924. In other words as of January 1 1943 20 years or longer had elapsed since these men were first exposed The 293 who were first exposed in 1924 or later were counted only after they reached the 20 years - since - first - exposure point .1 These dates are highly significant in that they show that calcium silicate insulations could not have been involved to any appreciable extent in this study Kaylo was the first of the calcium silicate insulations and it is barely 20 years old as of now It has been less than 20 years that any significant quantity Las been in the field The second point is this Asbestos is altered both chemically and physically during the autoclaving process in the presence of lime which which is involved in the manufacture of calcium silicate insulation Whether or not this altered asbestos possesses the same cancer inducing tendencies tendencies as the original asbestos remains to be demonstrated >fi >fi >fi ~ . $ , me wr W. C. Taylor 102 102