Document V3kvooq7yzqbnOQxYxQr4rgG4

confidential Interim Report to the Quebec A*bettoe Mining Association on Epidemiological Study of Lung Conetr in Ab*to< Worker* Tbift interim report is presented to acquaint the Acsociation with the progress of the work thus far and the plans for the remainder of the study. The.'objectives of the program as proposed in the memorandum of March 14, 1954 were to determine: 1. Whether there is relationship between asbestos;* and lung cancer. 2, Whether a relationship may exist between mere exposure to asbestos and lung cancer. Tbe suggested procedure included the following stepi; 1. An intra-industry study, selecting a group of people which entered the asbestos industry from ten to twenty years ago and following their future health status. 2, A comparison of this group with the general popu lation of the Province of Quebec. 0355 2. J. A comparison of the group under study ub the _ populations of the Dominion* of Canada And ol '' the United States* In line with these objectives And suggested procedure*, the initial effort was directed to the collection of dots reiAting to Ail workers who had been processed through the clinic At Thetford Mines, And of similar information on the workers at Canadian Johns-Manville Company in Asbestos, Following the initial visit in February, 1956, the first field work was begun in July at these two locations. Although the data in the two instances were not exactly similar in form, the inclusion of records from the personnel department at Asbeetos covering employees who had retired, died, or become disabled provided data sufficiently alike for the purposes of the etudy* Duta from these clinical records included the age, family and personal medical histories, smoking habits, number of years of exposure, on estimate of weighted exposure, and eventual course of health status or cause of death. Death certificates in the Province of Quebec for the years 1952 to 1955 inclusive were reviewed during the last week of July. This infer* mutton was obtained either from the death certificates themselves or from IhM cards summarising the certificates, in the Department of Vital Statistics of the Provincial Health Ministry. All cases in whieh death was certified as having been due to lung caneer were examined for such information as the 03 a plats of residence, occupation. date of death, hospital in which death occurred* and whether or not an autopsy was performed. Cases in which lung cancer was given ae a cause of death but ia which it was not specified as to whether thelung eaacer orifiaated in the lung were also studied. So September, additional data on provincial death certificates were collected and the records of the Sun Life Assurance Company of Canada were examined in order to obtain information on death claims paid tmder the group insurance policy covering the Canadian Johns*Vtanville workers. Statistics for the Province of Quebec, eclating to population, total deaths from all causes, toul deaths from cancer, and deaths from w lung cancer were collected and have been tabulated by counties and by sex for the years 1950 to 1955. These data are currently being processed ia savor&l different ways. Death rate# for the general population in specific years art being established. They will be classified according to total deaths, deaths from cancer, and deaths from lung cancer by county of residence and by sea for tbe years 1950 to 1995 inclusive. They will then be analysed to determine which factors seem to be related to any unusual incidence of lung cancer. Deaths from lung cancer among asbestos workers arc being determined from information contained in the clinical records as well as from the death certificates and insurance records. In order to verify the figures, the individuel deaths are now being reviewed with the phystcians 0357 4. Asbestos And At Thetford Mines. The verification will be carried? out for the death certificate information. Cn completion 0/ this phase, it will be-possible to establiab a list of eases in which primary cancer 0/ the lung has bees proved as the cause of death. All those cases in which lung cancer is strongly suspected hut unproved as the cause of death will be luted separately. Both lists will thes he subjected to careful analysis to detorminc possible relationships or correlations between lung cancer and any of the other factors known from the clinical records. Sueh factors assy include family history of cancer, personal history of boavy smoking, etc. Any apparent discrepancies in the correlations will carefully evaluated to avotd possible biss and to assure proper conclusions from tht resulting statistics. The "cohorts" being established for the Thetford Mines group and the Canadian Johns-Manville group will be used to make comparison of tbe health experience and tha death rates of asbestos workers between these two groups and between them and tbe general population. The death rate from lung cancer among these workers can be established and compared with the death rate from the same cause among tha general population and among specific segments of unesposod persons. After consideration of all factors affecting the comparability of the figures, the cohorts referred to are being established by picking out all employees of record for a selected year. Those still working at this urn* will be subtracted from this list. Of the remainder, those who have died of all causes will be studied exhaustively. There will, of course, be a few who will have been lost to the record, but every attempt will be made to reduce this number to an irreducible minimum. 0358 5. In Addition to the above, reUtcd bibliographic*: material has been collected, studied and abstracted. Particular emphasis is being placed on the accumulation of relevant background statistics. In summary, several available sources of data have been ex. amined to date. From these sources, information pertinent to the problem has been collected and is being reduced to a fora in whicn it can be eon* veftiently analysed. Meanwhile, the literature is being searched with re* lation to asbestosis and to statistics relating to the association between asbestoeis and lung cancer. Respectfully submitted, March I. Its? 0359