Document k61MGykaq0L18JpMxLgLY1Yay

J January 19, 1945 Mr. Ivon Sebourin Aldred Building Montreal, P. Q. , Canada Dear Irani I as enclosing; a copy of the tuberculosis mortality study which is at last completed* I believe that Z>r Cartier will be interested in it since he is the cnost logical person to take the initiative in carrying out some of the recomwendatloas* X had thought we would see you here before this, but no doubt some change in your plans has occurred*. I certainly appreciated your thoughtfulness in sending se the Christmas care of your hone under the snow* It reminded se of the nest hospitable week that Bill and X enjoyed with you* X also appreciate the assistance you gave us la securing the data froa which the enclosed study was node* Ylth kindest regards* Sincerely yours, DR. WrlEATLc'J _ Assistant Medical Director CS39 TjeztlC 'JLOStS AND ' AS86SWT& S : - ' A Grief rtAjiSJji trf CvyywJ t*KjvCtdft. A&0d*[fi40 &L i&*-6uj tnis Aten fti&vff tits eq. ~ria.-fft.-ttl Aumj , Ti GJ , 3h4w>1^ Csr-tyujsrtSi, Recent developments in Canada have focused attention on the question of the relationship between asbestosis and tuberculosis. Asbestosis has been declared a compensable disease in the Province of Quebec, thus increasing medico-legal interest in the establishment of this_jiiagnosis and evaluation of any contributing factors. Autopsy of asbestos miners has disclosed evidence of active tuberculosis and asbestosis in the same individuals. In Thetford Mines, where a substantial part of all the asbestos in Canada is produced, the mortality from tuberculosis has in the past 16 years approximately doubled in contrast to a significant decline in the Provincial rate. These developments have materially helped to create the impression in the Province of Quebec that there is a .causal relationship between tuberculosis and asbestosis similar to the V carefully demonstrated and generally accepted relationship between silicosis and tuberculosis. Observations in the Unite! States Previous studies of workers exposed to asbestos dust have not disclosed a higher incidence of tuberculosis among workers with clinical and X-ray evidence of asbestosis. (T) Lanza in 1935 concluded that asbestos dust did not predispose to tuberculosis. In his examination of 126 workers in the industry in the United States, 53.1$ were found to have definite X-ray evidence of asbestosis. Two cases of active tuberculosis were found. One of these was a worker with asbestosis. Q^)ln 1936 Donnelly reviewed X-ray film of 151 workers in asbestos mills anH found evidence of asbestosis among 34-4$ of the group. No cases of active tuberculosis were o<jJT found among workers with asbestosis. On the other hand, in the group with asbestosis he found 4 active cases of tuberculosis. Two of these active cases had been in the asbestos industry, 6 and 10 years respectively. Donnelly concluded that there was no tendency per se in this type of industrial occupation to exacerbate old tuberculous lesions. (3) McPheeters reported in 1936 an X-ray survey of 210 persons exposed to asbestos dust. He found 25.2$ had some evidence of asbestosis. Three cases of active tuberculosis were : C831 \ \ found. No tuberculosis was found in -workers with asbestosis. The three individuals with tuberculosis had been, exposed to asbestos dust 6, 9 and 10 years respectively. In five cases healed-pdlfionary tuberculosis and asbestosis were found in association. The average duration of exposure for the 5 was 10.4 years nri for the entire group 10.2 years. McPheeters decided there is no accelerating effect of tuberculosis on - asbestosis. \ In summation of this evidence it can be said that X-ray nH clinical studies among asbestos workers in the United States does not reveal a significantly greater amount of tuberculosis than found in the routine examination of workers in any industry. Moreover there is no evidence from these studies to indicate that long exposure to asbestos dust activates or accelerates the tuberculous process. Both these observations are in contrast to findings among workers exposed to free silica. Canadian Observations There have been no published reports of studies among asbestos workers in Canada with respect to the prevalence of asbestosis or of tuberculosis in the asbestos industry. Ir ' " and his associates examined physically and by X-ray 195 asbestos wwoorrkklfeecrr*ss -iifnnouA/rf sbestos and Thetford Mines^-^ ^A '*<****^1 TAAlii I Asbestos Thetford Mines # examined 141 54 % with more than. 10 years tifoiu.ru. 22 83.4 # with asbestosis % with asbestosis 12.7 24 44.4 One case of active tuberculosis was found among the 195 individuals examined. This is a very satisfactory incidence of tuberculosis among an industrial group. lineA in a surgey in 1940 of the garment trade when an ine&daaeo-ef 1 case was found in 200 individuals examined. Bedley 'i found that the tuberculosis mortality in Thetford Mines for the years 1926, 1927 and 1928 compared favorably with the tuberculosis mortality for the Province of Quebec. 08? 1. Table 2 Average Tuberculosis Mortality for All Ages per 100,000 Place 1926-23 1940-42 % Change Quebec 123.6 78.6 35 - Thetford 137.9 252.1 83 4 " this reiort of Pedlev there h&s b6en a. sharp change la tiA^relationshlp between Thetford Mines and the Province as a whole. Table 2 shows that In the Province of Quebec the average rate for the three years 1940-12 has decreased 35JC cornered to the average rate for the ears 1926-23. This corresponds to experience eleewhere tn Canada and the United States. On the other hand, in Thetford Sines for the corresnondlng period tuberculosis mortality has increased nore than SOf. The obvioue existence of a serious tuberculosis problem in tffif^MUJiily*has SfttfcSfe* speculation regarding the influence of asbestos dust. ,y Tuewft'toili flCKTAtl *Y frt'Oy -- If the industrial exposure'Is a significant factor in exacerbating or ocoelerating tuberculosis one would expect to find a significant difference in males over 25 years of i /UjU, att'tf ytt if jiftL'i+ff, twin , age since, in Thetford lllnesf^this part of the populationj[aeeBjiSete_yiij `fhti"ty Inrit vtahiel i Memeaimr sinrta $ocio-eoonomio factors are also significant in relation to tubercnlosl^Mm^'ttxaparlson of the tuberculosis mortality rates in Thetford (lines pith communities In the Province of like size, medical and public health facilities, soc,io-econom.ic and. rac.ia,l o,horacterlstlos ia Important.tublin has nointad out that _ where socio-economic factors were dominant the tuberculosife mortality rates fur both husbands end wives ware similarly affected; where industrial factors played a leading rolethe standardized mortality rates for the husbands greatly exceeded that of the wives. (p. 53. Tuberculosis in Industry - Saranac laboratory Symposium. -- - Through the courtesy of the ^Provincial tiesiy. najMBtmnnt 1941) g,7.d~ Dr.^Parrot, we were furnished the number of deuths from tuberculosis by age and sex for the years 1939 to 1943 for the cities of Thetford Hines, Rlmouakl, Chicoutimi, Cap da Madeleine, St. Hyacinths, St. Jean, and Valleyfleld, as well as for the Province end the Dominion as a whole. Of the six communities picked with these characteristics in mind, the town i, tevu>|adAa of RlaouakLmore nearly aBemupjSatrW Thetford Hines, except instead of asbestos mining Tafcta 3 --------- ----------- - f.t.-iTi- ,. Its principal industry is lumbering end rood 14eo fA*4-*- -if K, Shows tha^^Mortality Rate by Sex fMf All Ages in the Provinice wd in the Seven Cit_i_h_a___<t5t*0- nt. Tuberculosis Death Bate per 100,000 All Ages PB07IKCE OP QUEBEC Cap de la Madeleine St. Hyaointhe St. John Valleyfleld Chicoutimi Thetford Hines Riaousld. l&la 77.5 55.9 84.5 75.1 101.7 141.8 190.1 171.9 Female 80.8 44.5 90.9 109.8 85.3 149.1 223.9 287.3 0S32 Froi~Tab'ie Z~it will be noted that three of the--seven towns for which"data" whs"-----obtained have a tuberculosis mortality which is appreciably higher than the Provincial rate. Females in Rimouski have the highest average jrate for the years 1940-42. Females in Thetford lnes hava a higher average mortality for the corresponding period than males in Thetford -ines who ranked third in this analysts. -4- further analysis by ige and sex has beer. tte-.vrted for the contunitiea of r.imouskt ini Thetford "ines are? the results appear in Table 5- interpret?tlon is difficult because of the small number of persons involved in the ege groups in the tv.' comeunities. ft is of interest to note, hor.ever. that among Theforc .tiles the hig.naat mortality rate Is recorded in males aged 25-34. In F.lmousfci miles the highest rate is in the group 35 and older. Thetford females aged 25-34 have the highest rate in either male or female groups., being 519.3 per 100,000, or four times the rovineial rate for the same ages. The rate in the corresponding are group in piooushl females is 44^.4 which is nearly three tines the Provincial rate in the seme age group. Tuberculosis also _ takes a high toll in Rimnuski females 35 and older. Hare the rate is four times ta^, mln it~ pi `n fn ft i in Ti? n> oidT~. lAfilC. S Tuberculosis Deaths and Death Rates - per 100,000 - 1940-1942 Pror. of Quebeo Deaths Rata <^18 THmnnjH Deaths Sate Thetford IHn Deaths Rata All Ages 0-24 25-3^* 35 (- 3888 1167 803 1918 77.5 45.2 102.1 116.2 17 171.9 5 93.3 2 114.4 10 360.9 .>6 13 10 13 190.1 121.3 342.9 245.0 All ages 0-24 25t34 35 f Prov. of Quebec Deaths Bate Females lid monglH Deaths Sate Thetford Uinaa Deaths Rate 4019 1614 1072 1333 80.8 62.7 134.1 83.1 32 287.3 13 211.9 9 446.4 10 334.7 rsbuC *& 3.#.VTIV6 J4TA u,eTO 43 18 16 9 223.9 162.5 519.8 178.1 /TT\ Population Healthy Health Pub.H. Priv. Phys.Ratio tc Industries Officers Unit Nurses Fhvsicixna Pooulation Thetford Uines 12,000 Asbestos mining 1 15 12 1/1000 RlaonsH, Incl. suburbs Cap Madeleine 10,000 13,000 lunbericg,wood 1 finishing rubber mfg. 1 steel foundry, bag,nfg. silk 14 1*# 6 10 2 l/iooo 1/6500 1 Three Rivers 45,800 paper, linen mg. 1 1 9 40 rubber, iron 1/1150 Chicoutimi St. Hyacinths 25,000 18,500 aluminum,, pulp, 1 paper, iron fdry, clay products textile mfg. 1 1*** litwm 10 19 (incl. 7'specs) 1/4500 6 14 1/1300 Valleyfield 20,600 munition* , other 1 wax indBs cotton allk. i 5 10 full time health officers ** including 1 dentist Including 1 tb. specialist **** including 2 full-time physicians 1/2000 0834 -5DISCUSSION It'.is obvious that tuberculosis mortalitv is excessive in Thetford Mines But A there is no indication from these data that occiq>ation is a dominant factor.because: 1) the mortality is equally b&d-among females; 2) it is excessive in the age group under 24`.where there is little or no industrial exposure; 3) tuberculosis is also a serious problem in Rimouslci where there is no asbestos industry. The age and sex distribution of mortality from tuberculosis resembles the picture of tuberculosis in a heavily seeded, susceptible population with a substantial pro portion of the mortality occurring in both sexes under age 24 and the majority cf deaths under age 35- There is no evidence, if asbestos dust is a factor, that it resembles free silica in its influence on tuberculosis mortality. Careful and thorough mortality studiesamong granite cutters in the state of Vermont revealed that they are subject to an exeesstve frequency of deaths from pulmonary tuberculosis, not because of an exceptional risk of contact infection, or because of inferior physique, or because of unfavorable housing conditions or other sanitary deficiencies, but primarily because cf the occupational exposure. This same conclusion has been reached in every other study of workers who contract silicosis. Unfortunately we were unable to calculate expected deaths based on the Provincial rates because the age groupings obtained for Thetford Mines and Rimouski did not correspond to the age groupings available in the census data for the Province. Fcr further insight into the magnitude of the tuberculosis problem in these two communities,1 2 1. Based on current mortality data, tuberculosis in Thetford Mines, in contrast to many communities in the Province as well as the Province as a whole, has substantially increased. - 0835 2. Rimouski, a limbering town, comparable to Thetford mines in socio-economic conditions, medical and public health resources, has a high tuberculosis mortality comparable to Thetford Mines. 3. Analysis of the tuberculosis mortality by age and sex in Thetford Mines, in the other communities and in the Province shows that both males and females in Thetford succumb to the disease with approximately the same frequency. This is not the mortality picture seen where there is industrial exposure to free silica. L. Admittedly our data is inadequate for final conclusions, nevertheless there is no indication from this mortality study that demonstrates asbestos mining per se in Thetford Mines is the cause of the high tuberculosis mortality. 5 Further mortality studies should be made to construct expectancy tables for age and sex in Thetford Mines, Rimouski, and perhaps elsewhere in the Province. 6. Tuberculosis case-finding surveys should be made both in Thetford Mines and comparable communities. ^ ~ <~n t * * ^ .(p^ rrxM^- /y (< ^ r^--P j /^ u ^J,*/j^ 4,<P "% 3. h^c. i-^ - -'/ -J (^---Z^-Q* y ? ^ i^5 ' *-f^t ^ \ ^-/t/*- ^ C mi L f f ^\ sB.^lr ? i/. , ^ * -*1 J ^~7-> ^'f'fii/e/fi( l t L/ '> \ . %hut. *r. h-MfCru^ . hJ t /? A K~~l0fJ> 0837 o/~ \ r ^------- w ^>*-***/fyy