Document zQOnkkkKEaZeRvwjxREowGwMm

february 25, 1944 Hr. Ivan Sabourin ildred Building Montreal, P.W., Canada Dear Hr* Sabourin: I hare jour 1 attar of Pabruary 22 asking for eoaoenta os tha relationship batvaaa aabastoals and suscejjtlbllity to tuberculosis. This question cannot be answered decisively/from a study of post aortas materiel alona. Medical problaas of this nature ara usually soItad os tna basis of probabllltlas and It is this satter of probabilities on vhlch we need further aridanew In tha case of tuberculosis associated with asbestosls. Verawathar in his Memorandum an Asbestosls* Tubercle * r end December, 1933 sad January, 1934) adaits that the data on .:Jeet are maager.* Ea reports that of 374 worksrs while at work, _ showed signs of aetlTe tuberculosis and that tha Brltlah Silicosis . .asbestos Medical Board in its first periodic examination of workers la this Industry found only one case of asbestosls and tuberculosis la 1512 examinations. On tha other hand tha English post mortem material at that time rarealad 35.7Jf of the cases complicated by tuberculosis. (Subsequently be appears to have found more cases if Dr. Riddell is cor rectly informed). In tha publication eitad Karewethar concludes: The evidence therefore, points to the hypothesis that At present the added risk to asbestos wo-ter from pr.:'1 -.---a--r tuberculosis Is limited and daflnltalr less than in workers exposed to free silica; virulent wesire infections will aa la the general papulation, cause death; lesser ones will result in more widespread fibrosis than would appear in cases amongst the general population and slight infections, in common with many other affections, are likely to precipitate death in cases of advanced asbestosls where they wouldn't do so in the general population.* Cie underscoring is mine but I agree with'these views. When Dr. Merewether was 1a this country last year he visited me for several days and we spent most of our time discussing these problw 2e rtill accepts our experimental work which proves that there is no specific susceptibility to tuberculosis Induced by asbestosls and he,like ourselves, is anxious to accumulate comparative statistics from various parts of the world to establish the general clinical experience. (2) is 1. Indicated In tar last latter the Quebec experience la not yet analysed; there is only an Impression that most of the asbestos sorters die of tuberculosis without taking Into account the excessive prevalence of such lafectlcn among the population of the Province. This Uspresslon needs aerification by careful analysis of morbidity and mortality statistics collected from the employees of the asbestos Industry, from their faailles not exposed to asbestos dust nrf froa other commumlUas In the Province of Qu%b*c. Such data should then be coapared with similar statistics for asfbestos workers In other countries. If there Is a specific occupational predisposition to tuber culosis it will beeoms apparent os such analysus just as It haa for silicosis. Wherever silicosis Is being.created, the high mortality from tuberculosis cannot be hidden. I do not believe that there is such tuberculosis among asbestos workers In the United. 8tates and suspect that the excess aortallty froa this cause in England Is probably due to the low living standards of industrial workers. Possibly selection of cases coning to autopsy has Influenced the picture. American studies have this far failed to demonstrate enough tuberculosis among asbestos workers to cause comment. The U. 8. Public Health Service Study of Asbestosls In the Asbestos Textile Industry In Forth Caroline, (Bulletin 2X1), Issued in 1938, hardly mentioned tuberculosis, disslsslng the subject with the statement ' -age 51 that *there were only 2 eases of aetlve. pulmonary tuberculosis group* (5X1 employees). Shull, (Badlology 27, lo. 3 , 279-292: examined 71 of 100 cases discharged from the plants where the Health Serrlea made lta study 15 months later and found 8 eases complicated by tuberculosis of alight to moderate extent but only 2 were active. These two subsequently died of this cause and In 2 others the Infection later became aetlve. Shull states In his conclusions that asbestosls does not predispose to tuberculosis.* Presumably he infers, although he does not say so, that the X eases of active disease among 5X1 wortaaen represented accumulated disabilities whan the examination program was Inaugurated. Donnelly (.T. Ind. Bjg. and Tax. 18, Vo. X, 222-228:1936) also examined 151 discharged esployees Inctarting the 100 reported by Shall. He gives .v>re details an the esses of tuberculosis* One of them bad worked ln~tbe asbestos Industry for 5 months and the otners 15 months. Tbs remaining 2 had worked 6 and 10 years respectively ar.l their infections might have been aggravated by exposure to asbestos dust. He points out, however, that an Incidence of 2 eases among 151 Industrial employees Is so higher than In any other industrial group. VcPhseters, (J. Ind. Hyg. and Tax., 18, 229-239: 1936) likewise ex amined and reported on these eases and ha Is In entire agreement with the other report era. In his conclusions he states, *Vo activating or aggravating effect of asbestos dust or asbestosls or tuberculosis was observed.- PI nelly I believe I told you tbat I myself, had just re turned from Forth Carolina where I had reviewed chest films of some 100 employees of the local asbestos Industry and saw cnly one that showed any lxrtlcatla of adult type pulmonary tuberculosis. This was completely ! < i /. n" * Mr. Ivan Sabourln (3} February 28, 1944 healed. I consented on the fact to tha members of the Medical Board of tne 8tats Industrial Commission with whom I was conferring had th Chairmen, Vr. 7stal, told a that tuberculosis was a rar finding among asbestos workers although common enough la other Industrial workers la their state. Zt would therefore, appear that la lorth Carolina asbestosls does not favor or predispose to tuberculosis. Z have Just now completed a rwwiWw-of 123 films for an asbestos fabricating plant in another state, la th * plant the amount of severity of the asbestosls on tha first examine; .oa la 1930 was well aarked, approximately 40% of the group showing definite X-ray evidence of the disease. levertheleas, the total adult type tuberculosis rate was only 5%i four of these cases occurred in persons with ssbestosls and 2 of thea were considered probably active. A second er 'uination was wade upon 67 of the original group after an Interval of f years during which they remained at work, low the Incidence of asbest ,, had Increased to 62% but the tuberculosis rate had fallen to 2.9%. A third anamination was done on 57 of tha original group who still remained In employment after a further Interval of 3 to 4 years; in this group the incidence of asbestosls was over 80% but that for tuberculosis only 3.5%* In spite of excessive anounts of severe asbestosls tha tuberculosis rate remained within the Halts usually found In American Indus trial populations. The behavior of the tuberculosis In these people was not unusual. Tot txarple one man, a spinner for 13 years, was 31 years old when first examined. Be had at that time an early non-specific dust reaction and evidence of old tuberculosis in the top of hi* lungs. In two succeeding examinations his dust reaction steadily Increased to reseh first stage asbestosls 9 years after he was first seen. Els tuberculosis boweTer, remained apparently uninfluenced.. Most of the others behaved in the same manner. These people had already been exposed to asbestos dust for periods of 3 to 18 or more years when they were first examined I and the three subsequent axamlmatloxis during the foIlOTlBC 9 years give ; us a good opportunity to follow what might have developed, lo new ease I of tuberculosis appeared. If it had not by that time the chances were not very great that they would later. II After they left the asbestos industry we do net know what happened to most of them bat on a few therw arw insurance records that indicate the cause of death. Two died of tuberculosis. One had had his infection when he was examined In 1930 at the age of 50. At that tine he had an early asbestosls after weaving for 10 years and evidence of associated enroule tuberculosis. H# was advised to leave wnleh he did and died of hia infection about 3 years latwr. Th# second man aged 32 had been a weaver for 12 years and had first stag# asbestosls but no evidence of tuberculosis at the time. Be left hie Job after the j Xr. Iran Babourla U) February 28, 1944 first examination for reasons not stated, Three years later be was reported to bare died of tuberculosis In a saultorlua. Such eases could occur anywhere. It is possible that If we bad follow-ups on sen of t^se eases after they left the asbestos Industry ve would flrd sore persons who subsequently contracted tuberculosli. and died of It. 2re aver, the evidence now available Indicates nonsuch tendency. Anlaal experiments, contrary to those upon silicosis, disclose no theoretical reasons for suspecting that as bestosis creates asj special suscepti bility to the tubercle bacillus of Eoch. I aa becoming sore and sore convinced that that the high tuberculosis rates reported in English autopsy statistics are doe to causes other occupation. I believe tbat the sane aust hold true in Quebec where the aasust of severity of the asbestos dust reaction Is very such less than It Is In the fabricating plants In the United States. I believe I have covered the other points raised In letter and will therefore not prolong this discussion further. Yery truly your*. Leroy U. Gardner, X. 9. Director LOG:EH ee to Mr. Vandiver Brown