Document 91NmV8KyR8n4qZa6KaV5NXzJV

**$* m+* 14. i :. <'i ; 1.1*. .iL' .1JL * .t ' I* I- Following this exploratory survey, the Initial effort wa* directed to the collodion of data relating to all workers who had been proceteed through the clinic at Thetford Mince alnce Ua Inception In 1947, and altr.Uar Informa tion regarding all worker* at Aabeatoa, P.Q. Data from the clinical recorda Included the age, family and peraonal medical hlatorloe, amoking habit*, number of yeara of exposure, an eatlmate of weighted exposure, and the courae of the Individual's health status or the cause of his death. From this Information It was possible to formulate a "cohort" which could be well defined, should be representative of ths whole group, and could be followed for a definite period of time. All of the available experience Indl- ca'les that the development of asboatoale In less than flvo years of oxpoaure must bo somewhat rare. Accordingly, the cohort was doflned as Including every wop'nw who had a total exposure of five or moro yeara, and who waa on Qffne /hU r*t* S'* &*.**c* the employment rolls In 1950.4?hU cohort was then followed by means of fi yOcsec. /Vc-xvy^v. the annual physical examination records through a six-year Interval, 1950 through 1955. All data regarding this group were thon tabulated In order to determine the characteristics of the cohort. For those who survived the en tire period, referenco was made tu the physical examination results and x-ray findings at the end of the period. Those who had died worn tabulated separately and the cause of death corroborated by oxamtnatlou of the death cortlflcaios. A further search woo made concerning thoee In the original cohort who re mained unaccounted for when the living and the known dead had boon tabulated, They reproeonl mon who bad left omploymanl through retirement or resigns- tloo. Evontually, all but a small numb or of these were accounted for as either