Document G5Md9g7E5Rn25OENjDvw68n8r

4 c IVAN SABOURIN , Q.C. Exhibit Exam of Date ............... Official Reporter KATHY RYLANDSHOLf Plaintiff s ^ i ___ FK- 168 >r ALDREO BUILOING, MONTREAL November 11, 1957 Ed. Boadway, Esq., Manager, Quebec Asbestos Corporation, East Broughton, P.Q. Dear Ed, RE: Industrial Hygiene Foundation Study (Lung Cancer)__________ I am enclosing a self-explanatory letter. Kindest regards, IS/LS .< -e_ ^JL^* c9 6. &.Ky-% _ cJ UT-- l d-- -f COPY November 1th, lttT. Karl Lindt11, Esq., CbUn&ia - W.AJiX, Albertoe, PM, Dear Karlr- BE: INDUSTRIAL HYGENE FOUNDATION STUDY (LUNG CANCERJ.- Following tbe mbI I. H. F. (Mellon Institute - Pittsburgh) meeting T hew periled advance copy of the epidemiological isrvey era entrusted with the L R. F.. f enclose herewith a copy of the Summary and Coachuitoai Im* jow confidential information. The whole nmj, la prtM. will be awlleble la a few days aad mailed you. The eaeloaed photostat lb aot of the best quality aad 1 am alone guilty la that respect. I thought yea would he deeply laterested la haring as sooa as possible this ''summary aad coacluslcns" which tell us of the substance of the Hadlags la the report which, I suggest, la well preseated, has logical sequence sad Is particularly art unfavourable aad rather effectively combats the growlag concept of later years la Quebec City (Dr. Yldal was holding the fort coustrtenUy with the W. C. B.) la ^rishlagtea, aad la Europe where tt originated aad develops most. L B. F. seems to haw made the best out of the material awliable (cancer statistical data were ms you know excesstwly meagre ta the whole world and wry poor la the Province ms report of cancer as _ cause of death Is art compellable by law whereas v.g. Tuberculosis must fiT reported). The presentation of the surwy appears ubjectlw, to the potat, aad I strongly bellew Lamedlate attention should be gtwa to capitalising upon tbe report. Ivan Sabourin, Q.C. AIDKD BUILDING Montreal. fciirl LterUli, Aafctrtot, (*e. B- COP Y Mawbir 7th IPS? Tha mader--orlaq tad aoxglaal Uaas art mias (axoapt for the word "recorded" at page 7IJL br. Brkxa tad thour associated with kin la this work te ay aiodest cplaloa kata made their good work. I had a aimart to dlacuaa with i>r. Braua tha aaggestioas ha aaahas at the vary oad. as to taaepeadenf k-Kay readiag. This must aot ba eoa^nsed pejoratively aad eo as to lacrlmiaata tha reedlog methods cf our Doctors at Thatford aad Asbestos. Oar aeethod U/orthodox and is aetaatlficaUy aouad, objective aad la ao way malignatari, /a hat the report rmthar implies as to X-*vaj raadiag la that oar claastficatloa has lor object to determine tha various atafts at a algalfkraal fibrosis of asbestctic asture, "sigaificant" iaasai&g a fibrosis havlag reacted a stags where it assy ba said that It eeold play a part la tha caaaaitty of a cartala lacapaclty to work (preseotiy or la the tutor*). Ashestoats ta la oar view a disease wteaH has goat beyoari those preliminary atagss which are aot ta themselves signifiesat from a comreaaatloa petal at flaw. Tha author et the survey suggests that independent reacuag would taka lato cousideratiaa the preliminary stages of asbestosis (which wo eat aside as taUentilesat) aad would ciasally them as eases which woald ba reported for a atudy, such as that caodbctma by L K. T. Thus, the reported eases of asbestoat* (whether significant er wot) would be more consfeersble aad tha laag cancer incidence would fall below tha actual figures - - - bad I would rather sbaa seggestiag wa refer oar iwodlags to aa Independent source as I firmly believe our doctors at Asbestos aad Thatford ieUnas are eminently qualified fee readings aad that few are as qualified aaywhere. Yeurs faithfully. ITA* SABlXJADI Ivan Sabouhn, Q.C. ALDETD BUILDING Montreal. i 71 YI: SUhQdAlY AND CONGLUaONS Interest la to* enaction of whether fi^n may to aa at. s sciatica between loaf cancer aad astottosls or exposure tonsbee- toi tot tooa evidsst since to rtport la HU by Lynch end Smith of a caM ia which lo&f eaactr aad aebestosis *ere both present. At additional cattt la which tto two ditaatot coexisted ororo raporUd, * a cental association appeart to hart toea gradually accepted by many authors, although a few workera coaaidered toe eorrelatioa to to in conclusive. Caaet of lu&f cancer which had occurred among the at- a* beetot miners in Quebec had been carefully recorded over tto years*, sV aad the present study was commissioned ia an effort to determine whether a causal relationship did, in fact, exist between exposure to asbestos aad caacer of tto lsag. Inference to the literature shows a fremarkabls uniformity both ef method and ef conclusions. 2a general* toe method has toea to study a circumscribed series ef cates of aftottotis and to enumerate toots ia which loaf cancer occurred. The eeriet may consist of eases coming to autopsy or ef dstfh certificates mentioning aebertosia* and ' toe total amaber has served as tto denemiaator by which the number * ef lung cancer cases is divided to produce a certain "incidence veto'1. This rate, as reported by various authors has toea consistently Ugh, e end its uniformity is indicated by the following Audi or fclerewether WodUr yers Lynch It Cannon Cloyns Totals' Asbastocis Deaths 944 fZ . 115 40 111 Tii jOfLung incidence #5 is ' IT . * * ' u. 14.3 U.B ?.# & The eatable characteristic of all pterions publications is the adherence to tfrm derelopment of a percentage relatiensh^ in a relatirely small and rtry selected group ttf case a. Only Dell/^^ a * '. among all of tbs authors, has described e representative population group and studied it for tbs mortality tsta ft aw bag tomeSr and coca* o parod this rate with that for a control group. Bis teroatifatioa dealt ' .V". .v - - . -. with only 115 son fe the study population. v Sines most earlier stadias bad bean limited te * ** i * tha long eancara found ha certain eelected samples, each aa # coming to astopsy or death cerdfleatoo ha Shirk eshestads was tinned, it was apparent that they ceeld set fnlfiH te rsfdreeeeat* of aa epidomioicfleal and statistical approach te tha problem, fta pro- . . . '' . oont study was* therefore, designed te moot thersgrlrcmsuts df this *. a e method. m * * ** * .1 ** , tts . e . . * After a preliminary Surrey t explore dot smO ability ef reliahls Information. *.** . mines in Quebec. based aa medical records at the two mala, locations 14* 73. of these operations. Cohorts were defined according to certain cri teria and all workers who met these criteria were included in the study. Through their medical records, data relative to their charac teristics were c. 'lectsd and their status at the end of a six-year period * df observation was determined. In the case of those who had died, an exhaustive search of death certificates and insurance records was carried out in order to determine as nearly as possible the exact cause of death. Mortality rates from lung cancer for the general population of the Province of Quebec and its various counties and for the Dominion of Canada, as well as the United States were calculated from statistics a collected in the appropriate places. Comparisons of the rates obtained for asbestos workers and for the other population groups were made according to accepted statistical methods which have been explained in * some detail in section IV. Records were obtained on 6091 persons who fulfilled the criteria of our cohorts. It was not possible to trace 133 of these for the whole period, but 5771 of the remaining 5958 were found to be still living in 1955 or later. Of the 187 known dead, cancer of the lung was | considered to have been reasonably proved in nine and to be strongly I j suggested in three. j The members of the cohorts were studied with respect to age, length of employment, a weighted average of their exposure, their smoking habits. Four thousand, six hundred seventy-three 74. were found to be smokers within the definition of that term as used in this study. Thirty-four percent of the cohort were more then 45 years of age, and 30% had been employed for longer than 20 years. Thirty percent had a weighted exposure which placed th^m in cate gory m. The mortality rates for long cancer; as computed on the basis of six "proved" deaths among the Thetford Mines cohort and three * "proved" deaths among the Asbestos cohort, wore 27.6 per 100,000 for the Thetford Mines group, and 22.2 per 1Q0,000 for the Asbestos group. When the three "suspected" cases were added, the "total" rate a for the Thetford Mines cohort rose to 41.3-, The rate for the combined cohort was 25.5 per 100,000 for "proved" cases, and 34 per 100,000 for "proved" and "suspected" cases. The importance of the suspected . but unproved cases in determining these rates has been reiterated be cause it is likely that inch cases would not be included in the statistics for the general population. t i -+ -^ According to the findings in this study, the mortality rata from lung cancer does mot appear to increase with length of exposure or with degree of exposure, e fact which presents strong evidence e- g-a--i-n--s--t--t-h--e----c--a--r-c--i-n--o--g--e--n---ic--i-t-y---o---f--a--s--b--e-s--tos. . On this other hand, the study | indicates that cigarette smoking is a very Important factor in the in- ' cidenee of cancer of the lung. '\ A cumpartvosi oThelative frequency of lang esneer sad es- hestosis is less reeeeuring, bat we believe that la fryof na 75. under-reporting of asbestos is cases. The incidence of asbestosis indicated by the medical recorda la far below that which would be ^ expected on the baaia of ' ll previously published figure a. Naturally, when the caaea of lung cancer are compared with an artificially low figure, it a relative incidence will be higher than it ahould. However this may be, 12.5% of the recorded caaea of aafreatoala in this study developed lung cancer, a figure alightly lower than those quoted by authors who confined themselves to this type of comparison. Comparison of the experience among the asbestos milters with that of various segments of the uaexpoaed, comparable population . shows that the observed number of deaths among the miners is not significantly greater. The rate for proved cases among the asbestos miners (25.5 per 100,000) compares well with the rate of 2.5 per 100,000 for the rest of the Province, and 20.1 per 100,000 for adult males throughout the Dominion of Canada, ft also compares satisfacto rily with rates of ,37.2, 25.3, and 2,0 obtained from various sources for adult males in the United States. Finally, in this matter of com- parison. it would appear that the world-wide experience of persona ex posed to acbestos dust is not worse with respect to lung cancer than that t of the unexposed population. The counties surrounding the asbestos-producing areas, and in which it is presumed most of the asbestos miners live, have almost identical mortality rates with those of eight counties widely scattered It 76 through to Pro-rimea, and arc tower ton &SM (Br to fOmalndor of to ProTiacs, and mach fewer to* to nU for bTrsimnifl' * Uses 1940, tor* Urt Im & tuti to bhich to tof no*it of primary tracer of '' j long may be considered to bare top prorad. Approximately kiH of toco 4*00 wore aaoeciafeod with u> , .. f . . beetesis. All bat cu tod la to recognised "cancer agi" tad 01 loaat on*-third bad only to light*at exposure (category I) to Mbiitoi toot. Cone lotions On tbs basis of a cartful tad detailed otndy of what in *t ^* *' , . t balisrsd to ba complete aad raliabls data, it seems fair to conclude . . ' t ' , `* ** * \ that to asbestos miners at Tbatford idioms aad Asbestos 14 tiu Poo. riacs of Qoaboc do oot bars a significantly higbst death^tstetrom tong caaesr than do comparable tegmenta Of to general ^cptdetioa. Despite tbit, to result* ^uggsft that a minar whs iBovoldps to aabaa* *tosls dost bars a groatar likelihood of dersfeping cancer of to bag than a p*r*on without this disease. If# tuptet, bowseer, tbot andor* reporting of asbostosia catt bad Led to a fallacious |* fbla com* section. S * * .S 4 it > ,* >7 i 4 The death rats from lung candor In to areas eeatiagwon* to th* atbottot operations is comparable to tbit bi.areas widely scattered throughout the Proriacs of Quebec aad fi lower then 14 obms urbanised arsaa within the Proriacs. . V'N t: . iv- A;..' /V- * in * ' -** 4 4. * . ; `m***---i . *4T . * 77. The present study tndtc.au* tfrat the effect of cigarette smoking is a mack sort important cenaidfration in the production of luagr cancer than is exposure te asbestos, tad in this respect, it taads to confirm rocoat stadias dealing with tha S&ect of smoking. . - The welua of this tBrestlgattoa wo*uld beconsiderably an hanrad by cortiaatnf the observation of tbs cohorts formulated herein on. a yeer-by-yaar basis. It is strongly recommended that fee chest x-rays of all workers be submitted to an independent reading for tha diagnosis of asbestosis, since an inaccurately law incidence rata for this disease creates anartHically high r^iaUrt incidence for long cancer^ I < . ( * r tk.*