Document zb0Qnr8GrNNX14vjndBEe4DER

FILE NAME Industrial Hygiene Foundation IHF DATE 1958 DOC IHF042 DOCUMENT DESCRIPTION Journal Article - An Epidemiological Study of Lung Cancer in Asbestos Miners An Epidemiological Study of Lung Cancer in Asbestos Miners a a > fe DANIEL C. BRAUN M.D. and T. DAVID TRUAN M.A. Pittsburgh Ever since the pronounced increase in the incidence of lung cancer among males became apparent there have been attempts to associate it with one or another of the various elements in the environment of man The approach used by some workers has been to suspect one or several substances and then set about in an intensive search for lung cancer among persons who have had any exposure to those materials In this connection Smith 82 writes The tendency of authors reporting the coincidental occurrence of primary lung cancer with silicosis or with any other theoretical etiologic conditions has been to emphasize the percentage relationship in extremely small series of cases with control cases which are not in any way comparable It would seem inevitable that asbestos should come under scrutiny in this manner because prolonged exposure to this material is known to cause a specific type of pneu- moconiosis and because persons who show this form of pneumoconiosis often come to autopsy and provide a ready source of material for study It was in this way that reports of the simultaneous occurrence of lung cancer and asbestosis began to accu- mulate after the report of a case by Lynch and Smith8 in 1935. Within the next 10 years about 15 additional cases ported and in 1954 Merewether were re- r eviewed all deaths from asbestosis recorded in Eng- land since March 1924. Lung cancer oc- curred in 16 of these cases Gloyne whose work is also frequently referred establishing establishing connection to ste as establishing a connection between asbes9 tosis and cancer of the lung reported in 1951 that cancer of the lung was present in 14.1 of asbestosis cases examined by him In 1941 claimed to have mice which they Nordmann and Sorge > produced lung cancer in exposed to asbestos dust Since 1951 additional cases of cancer of . the lung coexisting with asbestosis have been reported and according to Hueper about 100 such cases had been reported up ~ to 1955. As a result an association between the two diseases appears to have been ac- cepted by many authors and several writers - - were using the term asbestosis cancer of the lung Werber in 1952 stated cate- cyt gorically that in % to % of cases of - ~ asbestosis after a latent period of about 1to 20 years carcinoma becomes estab- _ lished in the lung On the other hand not all authors ac- cepted this alleged association without reservation Saupe80 in 1939 reported that he had discovered no cases of lung cancer among 620 cases of asbestosis which he had examined and in 1942 Holleb and ** Angrist expressed the opinion that the number of cases of asbestosis with lung cancer was too small for statistical evalua- tion In 1947 38 Wegelius reported 126 radiologically diagnosed cases of asbestosis among 476 workers in Finland and found no cases of lung cancer in this group Goldblatt and Goldblatt in their section of Accepted for publication Jan. 20 1958 This study was made possible through a grant from the Quebec Asbestos Mining Association Medical Director Dr. Braun and Statistical Consultant Mr. Truan Industrial Hygiene Foundation Merewether's latest book state But at no stage in all these impressive researches was any clue obtained which might have offered any support to the possibility that asbestos could act as a carcinogen There 63+ also frequently referred to connection between asbes- - of the lung reported in of the lung was present| estosis cases examined by Nordmann and Sorge produced lung cancer in exposed to asbestos dust ditional cases of cancer of ~ ting with asbestosis have nd according to Hueper _ cases had been reported up sult an association between appears to have been ac- *- authors and several writers erm asbestosis cancer of er in 1952 stated cate- .. % to 17 of cases of * a latent period of about _ ~ carcinoma becomes estab- hand not all authors ac- eged association without 80 in 1939 reported that d no cases of lung cancer s of asbestosis which he and in 1942 Holleb and ssed the opinion that the s of asbestosis with lung smail for statistical evalua- 88 Wegelius reported 126 ignosed cases of asbestosis xers in Finland and found ng cancer in this group oldblatt in their section of test book state But at these impressive researches btained which might have port to the possibility that . et as a carcinogen There LUNG CANCER IN ASBESTOS MINERS is no reliable criterion by which one can anticipate carcinogenicity and as is well known relatively minute changes in the structure of a chemical carcinogen are suffi- eient to diminish or eliminate carcinogenic scheduled areas by which is meant those areas where processes are carried on which were scheduled under the Asbestos Industry Regulations of 1931 as being dusty There is furthermore a complete lack action If asbestos is indeed to be regarded as a carcinogen the need is felt to demonstrate some property which can be regarded as something more than inertness These authors advance the theory that until some more experimental evidence of direct carcinogenesis by asbestos or a decomposition product of it can be obtained of definition of terms as used in the published literature For example the term asbestosis as used may refer to changes observable only by microscopic examination of the lung tissue or it may mean a radiologically detectable condition Most of the published reports obviously included women among their cases but some of them do not give the number or asbestos might be considered as a car- cinogen which only induces a further de- velopment of a preneoplastic condition brought about by something independent of the asbestos such as an endogenous factor Thus the literature while tending to sup- port the thesis that asbestosis is in some way related to the development of lung cancer is by no means unanimous Alto- gether it is perhaps more confusing than enlightening A careful review shows that the majority of the reports are clinical and not epidemiological They lack many elements necessary for the application of epidemiological techniques to their content * and most of the authors do not make claim to having done so What has happened is that succeeding authors have drawn conclu sions and generalized beyond the scope of the works which they quote Nowhere for example have we found references to a population of asbestos workers although several authors who have quoted the ob- Served incidence of lung cancer in autopsies of persons who also had asbestosis imply that this incidence applies to asbestos work- proportion of women involved in the study There is also a lack of uniformity as to what type of exposure most studies have dealt with Of 99 cases enumerated by 58 Hueper in 1955 only 10 appear to have originated in the United States and 7 in Canada Some of the earlier reports ap- parently included asbestos miners but it can be assumed since 82 of the 99 cases had originated in England and since no asbestos mining operations are carried on in that country that most of the reported cases have involved workers in the textile or fabricating industries Such factors as smoking habits family history of cancer length of time in the industry and age of the individual case are also notably absent in the majority of these reports With this understanding of the limita- tions of the existing literature with respect to epidemiological generalization it may be of value to consider in somewhat more de- tail some representative earlier publications a few of which were referred to briefly ers generally unable to find We have any study likewise been which actually calculated the incidence of lung cancer among a population of persons who had asbestosis and not just those who came to autopsy With the exception of a paper by Doil none of those reviewed gave any data on exposure and dust concentrations and even Doll's paper merely mentions above One of the most detailed studies and one which deserves the most serious considera- tion is that reported by Doll 28 in 1955 This study reviews causes of death among asbestos workers based on coroners records It also attempts to estimate the risk by studying records of men who worked for at least 20 years in exposed situations 635 Truan HEALTH M. A. ARCHIVES OF INDUSTRIAL . # saad 46%. Doll concluded that lung cancer was a spe- lung cancer in other forms of pneumoconio cific industrial hazard of certain asbestos sis was 6.7 and in 169 cases teow which workers and that after 20 years of expo- proved not to have any type of pneumo- sure the risk is 10 times as great as for the general population This article is important for several rea- sons in addition to the definite conclusions coniosis it was 8.3 Gloyne considered the mortality of the asbestos workers to be disturbing First of all it is obvious that the paper does not deal with the mor- at which it arrives For example it begins by stating that in view of the infrequency of asbestosis this large number of cases tality of asbestos workers and secondly it must be borne in mind that all of Dr Gloyne's cases were submitted to him for 61 cases of lung cancer does not prove lung suggests cancer is an study because the findings were unusual for uncomplicated pneumoconiosis It can occupational hazard of asbestos workers Neither this article nor any previous one which we have examined presents any fig- reasonably be assumed that cases including those of asbestosis in which the findings were not considered unusual were not sent ures to prove that asbestosis is an infre quent occurrence Estimates of the number of persons potentially exposed to asbestos dust in the United States alone vary from 10,000 to 35,000 and the incidence of as- bestosis of any degree might be higher than to Dr. Gloyne for examination As a matsent ter of fact in the same paragraph in which he expresses concern over the incidence rate in asbestosis Dr. Gloyne himself points out that the rate for lung cancer based on necropsies at the London Chest Doll imagines Hospital was 21.3 while the figures of This study like so many others involves autopsy records The number of persons involved in the statistical analysis is only 113 representing only 1,042.25 years of life It is also true that in selecting men who had been employed for at least 20 the Registrar showed only 2.4 He thus recognized that autopsies on a cer- rep tain selected group of cases were not resentative of the general population It would seem then that notwithstanding the value of Dr. Gloyne's work its importance years the study automatically excluded those who died from other causes after as an index of the prevalence of lung cancer in asbestotics has been misinterpreted shorter employment by some who have quoted him All that it Another reason why this publication is of importance is a statement which it con- really shows is the fact that in a group of 121 cases selected for special study pri- tains to the effect that the strongest evi- dence that it lung cancer may be a hazard in asbestos workers has been produced by Merewether and by Gloyne marily because they seemed abnormal by preliminary examination 17 or 14.1 had lung cancer Merewether 3 in 1947. in the report of In 1951 Gloyne presented a review of 1205 autopsies on persons who had worked in various dusty occupations This number included 132 asbestos workers of whom 121 showed pneumoconiosis sumably asbestosis Primary cancer of the the Chief Inspector of Factories reviewed all cases reported between 1924 and 1946 in which asbestosis was the cause of death or a coexisting condition This work was later extended to include all such cases re- ported up to December 1954 by which time lung occurred 17 times in this group an there were 344 deaths including 205 males incidence rate of 14.1 for lung cancer and 139 females Among them were 55 among asbestosis cases coming to autopsy There were in his series 796 cases with sili- cosis and 6.9 of these also showed pri- mary cancer of the lung The incidence of cases % of cancer of the lung 41 in males and 14 in females It is quite possible that a large number of asbestotics who did not die of their asbestosis or in whose 636 Iul 17 June 1958 i : OF INDUSTRIAL HEALTH HEALTH LUNG LUNG CANCER IN ASBESTOS MINERS which other forms of pneumoconio- 6. and in 169 cases I have any type of pneumo- as 8.3 Gloyne considered " of the asbestos workers to death certificate it was not mentioned may have been missed The import of this % is enhanced by the simultaneous statement that the incidence of lung cancer in autop- sies of the general population is only % workers First of all it is obvious does not deal with the mor stos and secondly The danger of attempting to compare a rate found in 344 cases with the rate for the general population without respect to me in mind that all of Dr. for were submitted to him the findings were unusual ated pneumoconiosis It can age occupation and many other variables such as smoking habits is obvious Lynch who with Smith 66 had reported the first case in 1935 reported 4 cases of that cases including assumed tosis in which the - findings dered unusual were not sent for examination As a mat the same paragraph in which ~ concern over the incidence tosis Dr. Gloyne himself : the rate for lung cancer ' psies at the London Chest 21.3 while the figures of carcinoma of the lung in a series of 49 autopsies on workers in an asbestos manufacturing plant who were shown to have demonstrable deposits of asbestos in the lungs This of course is not necessarily identical with the disease asbestosis Lynch himself points out that although this is an incidence of 8.2 both figures are too small for very serious statistical types of calculation Nevertheless later writers General showed only 2.4 ized that autopsies on a cer rep- oup of cases were not have used this paper to strengthen the case for an association of carcinoma of the lung with asbestosis It is also of interest that the general population It : KlotzfounKlotdzfound Klotzfound only the same number of n that notwithstanding the cases of lung cancer in a series nearly 10 Dyne's work its importance F times as large i e 4 in 478 cases of the prevalence of lung can- asbestosis s has been misinterpreted . ve quoted him All that it the fact that in a grouofp| red for special study pri- they seemed abnormal by ination 17 or 14.1 had Behrens as cited by Merewether estiimated that of 309 cases of asbestosis in the literature 44 showed associated cancer of the giving an incidence of 14.2 This is an illustration of generalizing an incidence obtained in a group of cases in 1947 in the report of or of Factories reviewed between 1924 and 1946 is was the cause of death ondition This work was include all such cases re- mber 1954 by which time aths including 205 males which were undoubtedly reported only be cause some of them showed lung cancer to possibly hundreds of asbestotics whose cses were never reported The same applies to the conclusion of Teleky who appears to have reviewed reports of 39 autopsies on persons with asbestosis among which 6 cases of lung cancer occurred Information from sources such as these does Among them were 55 ancer of the lung 41 in males It is quite possible er of asbestotics who did asbestosis or in whose not justify generalizations with regard to mortality rates Perhaps no one has written so exten- sively on the subject as has Hueper In 1955 he reviewed the 58 cases reported Pol 17 June 1958 Braun Truan prior to that date and enumerated a total of 99. Eleven of these were those dis- cussed by Doll and may have been cases covered by other authors Eight were dis- covered by Kennaway and Kennawa6y2 in an analysis of death certificates and unless Merewether's study was incomplete these cases should have been included in his re- port Of the remaining 80 it is quite possible that the 31 contributed by Merewether and the 17 by Gloyne contain some duplica- tion with each other or with those of other English authors Principles of the Epidemiological Method Dorn 20 has pointed out that much of what is now thought to be pertinent concerning the comparative frequency of lung cancer in different population groups has been developed from the analysis of clinical material particularly surgical and autopsy records supplemented to some extent by the reported impressions of various clinicians based upon their personal observa- tions More recently however attention has turned to the systematic investiga- tion of this problem by the same methods that have proved so successful previously in the study of Communicable diseases that is to say by epidemiological methods In order to apply this method of investigation to the problem under discussion we were of the opinion that a study should be planned so as to provide 1 a defined population group 2 available data for all members of this population including the healthy as well as the ill 3 a sample which is truly representative of the population 4 reliable and valid observations relating to the problem of the study A serious defect common to most of the studies which have been reported is that little or no information concerning the healthy people in the group seems to have been available to the author In order to draw a generalization regarding all asbestos workers it is necessary for a study to in- clude living persons as well as the dead 637 ye A. M. A. ARCHIVES OF INDUSTRIAL HEALTH Limiting the investigation to cases coming to autopsy as has been frequently done in earlier studies still further restricts its use in generalization The problem with which we are concerned is whether asbestos miners experience more lung cancer than does the general population The answer necessitates the collection of reliable infor- mation on asbestos miners as a group as well as on the general population It seems advisable to discuss the differ- ences between the epidemiological approach and that used in the studies which have been reported to date A very important consideration is the fact that lung cancer in spite of its increasing numbers is still a disease of low incidence that is in a given population not many persons will contract this particular disease This fact requires that large samples or groups must be studied to provide meaningful results be found in another group of the same size information but representative of the general population It is true that investigation of cases from such a sample can furnish valuable for research but the use of this information in drawing generalizations is necessarily restricted It is the obligation of both the investigator and of those who read his report to make proper comparisons * and to draw only those conclusions which are valid and justified A good statistical occur- study of cases of cancer of the lung ring in a group of autopsies can lead to a . proper inference concerning the frequency of lung cancer among cases coming to Be autopsy but only to such cases For in- - pro- formation from such a study be jected to some larger group it is necessary ' that the autopsies represent a good sample such of that larger group To assume that is the case in any particular series is dan- Recognizing the difficulty of obtaining such large samples most earlier writers deviated from the epidemiological method and sought to circumvent the requirement of observing well persons by 1 comparing the relative frequency of cancer in vari- ous sites 2 comparing the relative frequency of cancer in a group of hospital- ized patients 3 comparing the relative frequency of cancer in a group of cases coming to autopsy Attempting to compare two population groups looking only at the relative fre- quency of cancer in various body sites may result in finding a higher percentage relative frequency in one of the groups when in fact the mortality rate of cancer of a particular organ is exactly the same in both groups This is very clearly demonstrated in the excellent article by Dorn.30 The mortality rate from a particular cause is the true measure of comparison It is apparent that selected groups such as hospitalized patients or autopsy cases may not be in any way representative of a larger group and that in dealing with such samples the observer may easily find more cases of a given disease than would gerous and likely to be false There is some danger that the * figures ^' reported by some authors may be miscon- strued as applying to asbestos workers or . the even asbestos miners when in fact authors in question do not make this gen- eralization nor can the generalization be | made for the reasons stated Close study of the reports reveals that the percentages cited relate only to the group of autopsies covered by the particular investigation The present study in contrast to the earlier works has been planned to utilize the epidemiological method A defined group of asbestos miners has been estab- lished in such a way that it constitutes a good sample of the whole population of asbestos miners in Quebec Data for all members of this group have been collected and analyzed Those concerning lung can- cer have received most careful considera- tion Details of the methods employed will be set forth later but the type of approach is considered to permit of fair comparisons and valid generalizations Collection and Analysis of Data _ A preliminary survey of potential sources of information in February 1956 involved 638 Vol 17. June 1958 OF INDUSTRIAL HEALTH size her group of the same e of the general population Investigation of cases from can furnish information earch but the use of this drawing icted generalizations is It is the obligation stigator and of those who make proper comparisons ly those conclusions which istified A good statistical i cancer of the lung occur- of autopsies can lead to a concerning the frequency among cases coming to y to such cases For in-such a study be pro- rger group it is necessary * 3 represent a good sample ~ up To assume that such = y particular series is dan- ~ to be false a : danger that the figures : authors may be miscon- *> g to asbestos workers or ners when in fact the =: ndo not make this gen- % can the generalization be ?: ons stated Close study of als that the percentages ' to the group of autopsies articular investigation tudy in contrast to the s been planned to utilize 1 method A defined + miners has been estab- way that it constitutes a the whole population of in Quebec Data for all group have been collected ose concerning lung can- most careful considera- te methods employed will but the type of approach ermit of fair comparisons zations 1 Analysis of Data arvey of potential sources February 1956 involved Vol 17. June 1958 LUNG LUNG CANCER IN ASBESTOS MIXERS discussions with the physicians in charge of the asbestos companies programs and with clinicians pathologists representatives of City and Provincial health departments and of the Canadian Cancer Society and other interested persons It was found that morbidity data although somewhat limited were available from such sources as the hospitals in Montreal and Quebec City and the 13 cancer detection centers in the Prov- ince However because of the high mor- tality in lung cancer it seemed advisable to depend upon data relating to deaths These we found to be obtainable at the vital statistics department of the Ministry of Health in Quebec City From the preliminary survey it was apparent that extensive and detailed information could be gathered with respect to both the persons employed in the asbestos mining industry and the mortality figures for the general population Following this exploratory survey the initial effort was directed to the collection of data relating to all workers who had been processed through the clinic at Thetford Mines since its inception in 1947 and similar information regarding all workers at Asbestos Que Data from the clinical records included the age family and personal medical histories smoking habits number of years of exposure an estimate of weighted exposure and the course 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 lefined should be representative of the whole group and could be followed for a lefinite period of time All of the available experience indicates that the development of asbestosis in less than five years of ex- posure must be somewhat rare Accord- ingly the cohort was defined as including every miner who had a total exposure of five or more years and who was on the employment rolls in 1950. Office and other nonexposed personnel regardless of length of employment were not included This cohort was then followed by means of the annual physical = examination through records through a year interval 1950 through 1955. All data regarding this group were then tabulated in order to determine the characteristics of the cohort For those who survived the entire period reference was made to the physical examination results and ray findings at the end of the period Those who had died were tabulated sepa- rately and corroborated certificates the cause of death by examination of the A further search was was death made concerning those in the original cohort who remained unaccounted for when the living and the known dead had been tabulated They represent men who had left employment through retirement or resignation Eventually all but a small number of these were accounted for as either living or dead and in the latter event the cause of death was substantiated in a similar manner and the results added to the original list of deaths Death certificates for the Province of Quebec for the years 1952 to 1955 inclusive were reviewed in the department of vital statistics of the Provincial Health Ministry together with statistical sum- maries of the causes of deaths in the Prov- ince by counties All cases in which death was certified as having been due to primary cancer of the lung were examined for such information as place of residence occupation date of death hospital in which death occurred and whether or not an autopsy was performed Cases in lung cancer was given as a cause of but in which it was not specified which death as to whether the cancer originated in the lung were also reviewed in an effort to include all instances of primary carcinoma of the lung in the study The statistics for the Province of Quebec relate to population total deaths from all causes total deaths from cancer of all types and deaths from lung cancer These were collected and tabulated by counties and by sex for the years 1950 to 1955. inclusive Braun 630 A. M. A. ARCHIVES OF INDUSTRIAL HEALTH From them death rates for the general In addition to this analysis of deaths oc- population of Quebec and counties were calculated for and analyzed by cause of individual specific years curring in the cohort and during the years under observation every known death from cancer of the lung as well as every case Practically all employees of one company are covered by a group policy of life insurance which fortunately nearly all of them continue to carry when they retire A very few are not covered by this policy and those who leave the industry for one reason or another except retirement usually are no longer covered but this is likewise a diagnosed but still living has been tabulated and analyzed They will be discussed separ- ately from those includedin the population and interval under study mortality A comparison of lung cancer mortality been in the producing counties has made with that in counties which are far removed from the asbestos mines and in small number As an additional check upon the information obtained from the clinical records on this group the records of the life insurance company were examined for all death claims paid under the policy and particular notice was taken of the claims in which the proof of death was based on cancer of the lung Deaths from lung cancer among asbestos which presumably no asbestos miners live Finally compari-% in order to broaden the in different population population son of death rates in different population groups the rates have been collected for - Canada generally and for the United States according to the most recent published and ~ unpublished material ts eM Results and Interpretation a miners were thus determined from the clinical records in the medical service of the industry and checked by means of the death certificates and insurance company records The deaths were then verified individually by reviewing them with the physicians in charge of the medical services In this man- ner there was established a list of cases in >. The cohort which was constructed accord- - ing to the criteria describedin the preceding section has been considered individually and~ compared with the general population~. Description of the cohort will be presented here as a preface to the results of the study - Original Cohort Lost Persons Deducted 6,091 133 which primary cancer of the lung is considered to have been proved as the cause of Final Cohort Living in 1955 Dead by 1955 working and retired 5.958 5,771 187 death A few cases in which lung cancer is Cancer of lung 9 Questionable cancer of lung 3 strongly suspected but not proved as the Other causes 169 cause of death were considered separately Mortality rates have been calculated using both the proved and the total of proved Unknown causes Smokers Nonsmokers Unknown 6 4,673 1.265 20 and suspected cases during the years under observation Comparisons were then made between the death rates from the same Tables 1 2 3 and 4 present age number of years of employment weighted average exposure and smoking habits of the cohort cause among specific segments of unexposed persons All lung cancer deaths both suspected and proved were carefully ana- A comparison of the exposure to asbestos dust is presented in Table 3. All members of the cohort were placed in one of three lyzed to determine possible relationship or correlations between the development of categories representing increasing degrees of exposure based on a weighted average lung cancer and any factor known from the of the years spent at various levels of clinical records such as family history of dustiness The degree of dustiness for each cancer personal history of heavy smoking job category was determined after consulta- coexistence of asbestosis or exposure to tion with persons familiar with the environ- asbestos ment and conditions in the various work 640 Vol 17. June 1055 OF INDUSTRIAL HEALTH > this analysis of deaths oc ohort and during the years on every known death from ung as well as every case till living has been tabulated They will be discussed separ e included in the population il under study ts 1 of lung cancer mortality producing counties has been in counties which are far the asbestos mines and in ly no asbestos miners live ler to broaden the compari- ites in different population es have been collected for , and for the United States 4. most recent published and erial S$ + i 6 ac ord- and Interpretation ich was constructed accord- a described in the preceding considered individually and the general population ~ he cohort will be presented : to the results of the study - co 6,091 1 133 5,958 ng and retired 5,771 187 5 xer of lung 3 169 6 4,673 1.265 20 and + present age number loyment weighted average oking habits of the cohort of the exposure to asbestos in Table 3. All members re placed in one of three enting increasing degrees d on a weighted average ent at various levels of gree of dustiness for each determined after consultafamiliar with the environons in the various work Vol 17 June 1958 LUNG CANCER IN ASBESTOS MINERS Number and Percentage Distribution TABLE by Age Table Number and Percentage Distribution by Length of Employment AFS Number Per Cent EmLpelnogythmeonf t Number Per Cent ; 3.901 829 1,124 829 615 829 315 5 . 18 5,958 18 1,595 89207-18 2.398 89207-18 89207-18 922 89207-18 603 89207-18 15855 89207-18 5,958 89207-18 Less than % areas For the purposes of calculation the assumption has been made that the relation- ship between these categories is linear and that Category II is twice as dusty and Category III three times as dusty as Cate- gory I. ually smoking more than five cigarettes per day Persons who smoke pipes or cigars exclusively were not considered to be smokers for the purpose of this study Table 5 presents the year experience of the cohort and indicates the TABLE Number and Percentage Distribution by Exposure Category Table Number and Percentage Distribution by Smoking Habits Totala Average Exposure 1,772 6,968 2.0 * 88 88 * Number 4,673 1,285 20 3,958 Per Cent ea ea ' 100 . than 0 The fourth variable smoking habits was . similarly tabulated and is shown in Table 4. This was included because the informa- tion was available and because smoking was regarded as one of the variables which besides the environment could conceivably influence the development of lung cancer As used in this presentation the term smoker refers to a cigarette smoker habit- number of deaths each year from specified causes In general a case was considered to be proved as one of primary cancer of the lung when the records showed that the diagnosis had been supported by an autopsy or surgical resection of the lung with microscopic examination of the removed tissue In one case so considered however diagnosis was confirmed by bron- Table Year Experience of Cohort and Death Rates per 100,000 Years of Risk Cause of Death Year Year No. Alive At Beginning of Year 5,958 5.942 5.922 5,885 3,848 5,810 Proved Primary Ca. of Lung -202-310 -202-310 -202-310 -202-310 -202-310 -202-310 Suspected Primary Ca. of Lung 20 16013 20 16013 20 16013 2016013 20016013 20016013 Totals ac cennccceceseee : -202-310 20 16013 Proved rate per 100,000 years of risk- 25.5 35,271.5 35,271.5 12 " " Total rate per 100,000 years of risk 33,271.5 = 34.0 Other auses 20538818 20538818 20538818 20538818 20538818 20538818 20538818 Unknown aloro rf aloro rf aloroorf aloroorf aloro rf aloro rf aloroorf Years of Risk 5,950 5,932 5,903.5 5,886.5 5.820 5,790.5 35.278.5 641 Truan Case No. 4 2 3 4 3 8 7 a 9 HEALTH | M. A. ARCHIVES OF INDUSTRIAL Table Prozed Cases of Primary Cancer of the Lung Age Smoker 8 3595863 Yes 883595863 Yes 883595863 Yes 883595863 Yes 883595863 Yes 883595863 Yes 883595863 Yea 883595863 Yes 883595863 Yes Exposure 28 yr in Cat II 34 yr in Cat I 37 yr in Cat 32 yr in Cat I 22 yr in Cat II 33 yr in Cat III 30 yr in Cat II 16 yr in Cat I 28 yr in Cat III Died 10-12-31 5-3-55 5-3-55 7-20-35 8-20-30 451 4-30-53 11-22-83 &- 5-5 - +88 Autopsy Yes Yes No Yes Yes Yes Yes Yes Bronch ey Asbestos xcs No No Yes Yeq Yes No No choscopy with visualization and biopsy In another although there was no autopsy the diagnosis of primary cancer of the lung seems to have been beyond question The term suspected primary cancer of the lung was applied to those cases in which the diagnosis remains in doubt but some of the evidence points to cancer of the lung There were three such cases The term years of risk has been used to mean the number of men at risk for the year under observation A person who lived throughout the year was counted as a full year of risk but one who died during the year was counted as half a year _ Deaths occurring in the cohort and in which lung cancer is considered to have been proved as a cause are shown in Table - 6. In Table 7 are shown three deaths which have been considered as suspected lung cancer cases _ An indication of the importance of these suspected cases in interpreting the results of the calculations is desirable before fur- ther discussion of the mortality rates which are derived in later tables For example it happens that the rate found for the proved cases is close to the expected rate based on the general population figures for the Province as will be shown later and on this basis we should find eight deaths from lung cancer among the cohort Actually nine cases were observed If however the 3 additional suspected cases were included increasing this figure to 12 the total would be very close to the 95 level of significance However having found just and 12 cases we are not above this level Ss therefore the hypothesis that asbestos miners lung do not have a higher mortality from cancer than does the general population can-. not be rejected Nevertheless the occur- . rence of 12 cases in this sample would- increase the rate to a point which approaches the significant level Because of the tre- mendous importance of the questionable . regarding cases in this respect some detail them will be given here In one of these cases the suspicion of cancer of the lungis based upon the ray ~ interpretation and although no autopsy was performed the death certificate indicates . that death was due to lung cancer It is well known that the ray appearance of fibrosis especially if a localized density or a superimposed tuberculous lesion is pres- ent can simulate that of a tumor and by itself does not justify the inclusion of this case as one of proved cancer of the lung A second case was certified as having died by reason of hydrothorax possibly due to lung cancer but again there was no surgery and no postmortem examination In the third case although it was subjected to autopsy two pathologists disagreed as to whether lung cancer was present The death was certified as having been due to chronic myocarditis with nephritis and pulmonary * congestion and possibly cancer of the lung On the basis of these facts it seems unwar- ranted to include these three cases among TABLE Suspected Primary Cancer of the Lung Case No. 123 123 123 Age $ 98 98 Smoker Yes Yes Yes Exposure 32 yr in Cat III 33 yr in Cat III 12 yr in Cat II Dled 10-25-50 7--53 7--53 9-30-55 Autopsy No Yes No Asbestosis No Yes No 642 Vol 17 June 1958 F INDUSTRIAL } HEALTH HEALTH LUNG CANCER IN ASBESTOS MINERS f the Lung > Autopsy Yes Yeg No YYeess Yes Yes Yes Bronch Ashestogis -_, Yes Ne Ne Ves Yes Yes No No uneen, close to the 95 level However having found just I not above this level and othesis that asbestos minersuy igher mortality from lung the general population can- |. Nevertheless the occur-% es in this sample would 2. o point which approaches < vel Because of the tre- $ proved instances of lung cancer On the other hand they cannot in fairness be dis- regarded completely It is for this reason that mortality rates have been calculated buch ways Table 8 gives the rates by age groups The rates by length of employment are shown in Table 9. During the first 40 years of employment the rate rises an observation which seems plausible since the men were growing older However after 40 years of exposure there are no proved cases reported for a total of 240 men dur- ing the six years or about 1440 years of exposure When the suspected cases are added one case does show up in this Table Lung Cancer Deaths by Age Groups ance of the questionable aifi M i:5 ect some detail regarding n here = Number of Persons and Number of Lung Cancer Deaths No. of Deaths Age Group No. of Persons Proved Total se cases the suspicion of |: & g is based upon the ray =F ~ , although no autopsy was leath certificate indicates & I 1430012 3.901 L 1430012 1,124 615 $ 1430012 315 4 1430012 3 Q 1430012 Totals 5,988 9 1430012 =ce ue to lung cancer It is % the ray appearance of if a localized density or ' aberculous lesion is pres- that of a tumor and by stify the inclusion of this proved cancer of the Table Lung Cancer Deaths by Length of Employment Number of Persons and Number of Lung Cancer Deaths Length of Employment ....... No. of Persons 1,795 2,398 922 603 185 55 5,958 No. of Deaths Proved 0 m50010 m50010 m50010 m50 10 m50010 Total 0-31-2012 0-31-2012 0-31-2012 0-31-2012 0-31-2012 0-31-2012 0-31-2012 Annual Lung Cancer Death Rates per Years of Exposure 100,000 Employment Proved Orxg001a Orxg0 1a Orxg001a Orxg001a Orxg0 1a Orxg01a Orxg001a Total 0-38801 0-38 01 0-38801 0-38801 0-38801 0-38801 x dicates that the members of the cohort did not die from lung cancer at a younger age than the general population The rates by weighted exposure are shown in Table 10 and it will be noted that they present strong evidence against asbestos being a carcinogenic agent for if exposure to asbestos is in any way connected to lung cancer we would expect that the longer and heavier the exposure the higher the rate that would be found The only possible error in this interpretation could occur if the weighted exposures were inversely related to years of employment se was certified as having nydrothorax possibly due ut again there was no ostmortem examination Ithough it was subjected hologists disagreed as to r was present The death ving been due to chronic nephritis and pulmonary ssibly cancer of the lung se facts it seems unwar- these three cases among ing Autopsy No Yes No Asbestosis No Yes Vol 17 June 1958 TABLE Lung Cancer Deaths by Exposure period This would produce a rate of 69 per 100,000 again demonstrating the im- portance proved because of these cases to questionable but un- the final conclusion if there were no cases in this number of men with long exposure and if asbestos is a carcinogenic agent it must be concluded that these 240 men have demon- Category Number of Persons and Number of Lung Cancer Deaths Exposure Category I. eran No. of Persons 2.031 2,150 1.752 5 No. of Deaths Proved / /201 / /201 / /201 / /201 Total 4 4 4 0 Totals 5,958 12 strated considerable resistance This is a bio- | logical phenomenon which has been observed previously and is consistent with the theory of an intrinsic or endogenous factor in cancer The only other explanation would be that the susceptible members of this age Annual Lung Cancer Death Rates per 100,000 Years of Exposure Proved 302013 302013 302013 302013 Tota 365 365 365 group had died earlier of lung cancer Table 18. which appears later in this section in- 302013 12 643 Braun A. M. A. ARCHIVES OF INDUSTRIAL HEALTH TABLE Number of Persons in Various Weighted Exposure Categories by Length of Employment TABLE Lung Cancer Death for Smokers and Nonsmokers Weighted Exposure Number of Persons and Number of Lung Cancer Deaths by Smoking Habits Length of Categories Un- No. of Deaths Employment 1 II III known Total ees Persons Proved Total Hare 5-9 10-19 707 598 490 663 883 851 omammeln 1,795 omam eln 2,398 Smokers 4.873 00010 2002 20-29 314 363 243 omammeln 92a Nonsmokers 1,285 00010 2002 2002 30-39 247 218 137 omam eln 603 Unknown 20 00010 40-49 D+ 76 41 omam eln 185 psy 67 10 omammeln 55 Totals 5,058 00010 2002 Totals 2,031 Average years exposure = 173 2,150 17.8 1,772 16.6 omammeln & 5,958 17.5 Annual Lung Cancer Death Rates per 100,000 Years - of Exposure by Smoking Habits fi. in which case the heaviest weighted exposure Category III would show the shortest length of employment Table 11 which lists the number of persons in various exposure categories by length of employ- ment indicates that this error has not oc- curred In fact the average number of years of employment for each exposure category is almost identical No. of Deaths * Proved Total Clo k 100 Clook ~ = ad smokers may have included a larger ' percentage of young men Consequently ad- ditional Tables 13 14 and 15 were con- structed to show the distribution of smokers Table 12 which develops the rates for smokers and nonsmokers is most striking It shows that not a single case of lung cancer developed among the 1265 nonsmokers and that all cases of lung cancer both proved and suspected occurred in smokers Table 12 was so striking that it was felt and nonsmokers by age length of employment and degree of exposure Although there are slight differences they do not account for the fact that all observed cases ~ of lung cancer were in smokers In respect to age Table 13 the combined average age of the smokers was 4.9 years less than | that of the nonsmokers Table 14 shows that was tion further verification was necessary It possible that some abnormal distribumay have occurred g the non- TABLE Number_and Number_and Percentage Distribution of Smokers and Nonsmokers by Age Groups Number that as far as length of employment is con- TABLE Number and Percentage Distribution of Smokers and Nonsmokers by Length of Employment Length of Employment Number Smokers Nonsmokers Unknown Age Group Smoker Totals Average 3,200 898 411 164 2 4.673 4.673 39. 3 Nonsmoker 689 224 202 150 0 1,265 44.2 Unknown 12 4 2 t 1 - 20 40.7 50 eee eee e ee employment 1,408 1.967 722 433 110 33 +.673 +.673 17.0 377 426 199 188 7.5 2 1,265 1,265 19.3 0 /2 0 /2 0 /2 + 0018 0018 0018 0018 16.0 Percentage Distribution Smoker Nonsmoker 88.3 19.2 8.8 3.5 54.5 17.7 16.0 11.8 0.0 100 100 * Less than 0.05 Unknown 60.0 20.0 10.0 5.0 5.0 100 644 Percentage Distribution Smoker 30.1 42.1 15.4 9.3 2.4 0.7 100 Nonsmoker 29.8 33.7 15.7 13.1 5.9 1.8 100 Unknown 50.0 20.0 10.0 20.0 0.0 0.0 100 l'ol 17 June 1958 F INDUSTRIAL HEALTH FLUNG CANCER IN ASBESTOS MINERS Lung Cancer Death for 7s and Nonsmokers = nd Habits Number of Lung Smoking Cancer Cancer Drau Persons No. of Deaths Proved Total FT TABLE ; , ee 15 NumNb umberer and PercentaPgercentagee Distribution of Smokers and Nonsmokers by Exposure Category Supistare Supistare Number Smokers Nonsmokers Unknown 1.553 474 Bloove 1.691 452 Bloove 1.425 38 Bloove t 1 Bloove Totals 4,673 1,265 Bloove Average category Average exposure 2.0 1.9 2.3 Demography in the Provincial Ministry of Health The data on total deaths deaths from all forms of cancer and deaths from cancer of the lung were obtained by sex and by county for the years 1950 through 1955. In addition all death certificates which specified primary cancer of the lung and all those which indicated lung cancer but did not specify the origin were examined for the years 1952 through 1955 Percentage Distribution Table 16 gives a tabulation of the number Exposure [ . II . Unknown Smokers 33.2 36.2 30.5 @2 Nonsmokers Unknown 37.5 35.7 26.5 at 20.0 35,0 45.0 0.0 of deaths from lung cancer in the Province and in the cohort for the years 1950 through 1955 and shows the annual rate per 100,000 in these segments It will be noted from the Totals 100 100 100 table that the mortality rate for the ave included a larger s^' g men Consequently ad3 14 and 15 were con- Si he distribution of smokers age length of employ- 3: of exposure Although cerned the smokers had worked about 2.3 years less on the average than the non- smokers With longer exposure and greater age one would expect the nonsmoking group to show a higher rate if lung cancer were due to asbestos Table 15 shows that proved cases in the cohort is only slightly higher than the rate for the Province When the suspected cases are included in the calculation the rate for the cohort rises to 33.8 per 100,000 which is about 50 higher than the rate for the Province This it will be recalled from the previous dis- ct that all observed cases * re in smokers In respect ) the combined average was 4.9 years less than okers Table 14 shows ~of employment is con- ~ the average exposure category was almost the same for the two groups Therefore a this variable seems to be of no importance P in accounting for this difference cussion of the effect of the suspected cases on the results approaches but does not exceed the significant level One further interesting observation from The result of this additional analysis is that none of these factors appears to lessen ' Table 16 is the rather marked increase in the total number of cases for the Province the effect of Table 12 between 1950 and 1955. It is assumed that and Percentage Distribution Vonsmokers by Length mployment vanaber avs) Nonsmokers 377 % = 426 2 426 168 @ 12628 im 1,265 o 19.3 Unknown 10 *** 0 * 18 16.0 Distribution ker = Nonsmoker t 20.8 15.7 4 13.1 & : 1.8 a % 100 Unknown 30.0 10.0 20.0 0.0 0.0 100 Comparison of the Cohort Experience with that of the Province of Quebec Do- minion of Canada and the United States. In order to make a comparison of the experience among asbestos miners with that of the general population of the Province of statistics statistics Quebec statistics were gathered as stated in Division Division earlier in the office of the Division of at least part of this increase is due to im- proved recognition and reporting of lung cancer during the interval For this reason the years 1954 and 1955 were thought to be more nearly representative of actual condi- tions Even so it is population is general population is with cancer with the same quite likely that the studied not studied for lung diligence with which diligence with which Table Comparison of Cohort with Province of Quebec Annual Lung Cancer Deaths Number Number 1960 1951 1962 1953 1954 Rate per 1955 Total 100,000 Province Province Cobort Total 1,198,000 196 230 246 303 303 357 1,624 ms 5.923 002 NIJ \ NIJ NW I 3 12 83.8 NW i 3 9 25.3 1,192.000 193 218 002 300 302 354 1,612 ms excluding asbestos workers figures been ampumed all male lung Approximata Approximata midpoint midpoint of the population for mographie enumerated Number alive in cobort at beginninogf 1952 cancer deaths are for men of 20+ years 1961 and the estimated population for 1964 Rapport Div de la De Pol 17 June 1958 Truan 645 Age Group M. A. ARCHIVES OF INDUSTRIAL Table Lung Cancer Deaths for the Province of Quebec * HEALTH Number of Deaths SSS 1954 Estimated Population Total Certifled Total Proved 137,000 - 568318 818885 121.000 568318 818885 1,237,000 568318 818885 Specified Primary Total 11 31888 31888 31888 Proved 31888 1955 Total Certified Total 17 630 117 148 342 Proved % 35 5? wa 155 Specified Primary Total Proved 17 9 56 32 116 148 337 Death Rates per 100,000 Age Group Total Certified Total Proved Specified Primary Total Proved 2.2 33.2 73.0 01.7 1.7 1.7 27.3 27.3 02 1.4 21.3 50.4 58.2 12 14.4 23.4 24.0 23.8 97 15.4 8.0 '* Data from death certificates In REasptpiomarttefD or pi opoppuluatilonv atipopuolatinon obtained Demographie apaplpyipnglying 1951 percentages ffoor age groups for Total Certified Total 2.2 29.7 85.4 122.3 27.6 Proved 1.2 17.3 41.6 14.6 12.5 Specified Primary Total 2.2 27.7 84.7 122.3 Proved 1.2 15.8 41.6 14.6 27.2 123 males to the total populaftori1o9n54, as given this disease is looked for in the miners and it seems probable that the mortality rates for the Province may be low This would appear to be substantiated by the fact that the reporting of cases in the cohort showed no such increase over the same period Table 17 was compiled to show the an- nual specific lung cancer rate of cases in which the death certificate merely read cancer of the lung as distinguished from those in which the diagnosis was confirmed by autopsy surgery or biopsy The term specified primary refers to those cases in these two categories in which the tumor was specified as having originated in the lung It will be noted that of the total cases reported in 1955 a much higher percentage than in 1954 were specified as primary The table also shows that a higher percentage of the total cases certified in 1955 were proved again indicating increasing interest in this disease A comparison has been made between the specific rates shown in Table 17 and those for the cohort shown in Table 8 An average of the 1954 and 1955 rates for the Province has been used since the 1955 This comparison summarized in Table 18 shows that the observed number of deaths in our sample is not significantly greater than the expected number of deaths based on the average of the 1954 and 1955 figures for the Province It is true that in the case of the age group of 65 and over the five deaths provide a figure which is almost significant at the 95 level How- ever it should be noted that this number includes one of the suspected but unproved cases previously referred to Furthermore it is rather likely that the rate for the general population is understated in this age group for the obvious reason that the exact cause of death in the very old is not TABLE Comparison of the Actual and Expected Number of Lung Cancer Deaths by Age Among Asbestos Miners Group Province Total Specified Primary Rate per 100,000 45-5 1.8 45-5 24.5 56-64 67.8 65+ 89.8 Unknown -- No. Miners Observed No. ExN peo ct.ed of Deaths Deaths Proved Total 3,901 1,124 815 315 3 0222 I 0222 1 0222 3 14 - fy) . 8355 8355 8355 8355 - figure was higher and may have been ex- ceptional of * The expected number based on the average the 1954 and fos the 1965 specific rates Province of Quebec - Actually 0.4 Mange 646 Vol 17 June 1958 Bre INDUSTRIAL HEALTH Quebec SSN SEEEETEy 1955 Certified Proved > 3366331122 36312 36312 Specified Primary Total Proved 17 17 # 116 4319 148 4319 337 4319 . * 1955 Certified Proved Specified Primary Total Proved 12 17.3 27.7 41.6 84.7 1.7 14.6 122.3 41.6 123 Fa Pry n summarized in Table | he observed number of mple is not significantly spected number of deaths ge of the 1954 and 1955 | ovince It is true that in e group of 65 and over rovide a figure which is at the 95 level How- noted that this number ^ suspected but unproved ferred to Furthermore that the rate for the is understated in this obvious reason that the h in the very old is not Cancer rison of the Actual andand ber of Lung by Age Among stos Miners Observed No. No. Expected No. of Expected Deaths Miners Deaths Proved Total 3,901 1,124 615 315 3 Ot - 2 3 "1 2.544 z 0 > Quebec based on the average Province of orese Vol 17 June 1958 CANCER CANCER IN ASBESTOS MINERS LUNG LUNG Age Distribution of Adult Males for TABLE the Province of Quebec 1951 Table Annual Death Rates per 100,000 for Cancer of the Lung in Canada _ Groups of Years Limip Age Total Province Number Percentage 727,135 322218 188,962 322218 128.944 322218 133,487 322218 322218 1,158,498 322218 Percentage in Cobort 822-18 822-18 822-18 822-18 822-18 Trap * Rapport 1984 intensity a matter matter ofof thethe ssaammee intensity ofof iintnertesetrest as it is in younger persons Table 18 also answers a question pre- Age Group Under 30 30-34 35-30 40-44 30-64 P70o-7n4 8800--8844 All Ages 1931-1933 0,2 0.9 2.0 3.0 B 12 15.1 10.7 15.B 11.4 2.8 1941-1943 0.3 0.9 3.2 5.4 1188..99 34.5 30.6 27.9 14.3 7.1 1950-1952 1.0 0.8 3.0 8.5 37.2 59.7 102.0 86.3 83.9 71.0 15.8 * Mortality from Lung Cancer in Canada 1931 to 1962 viously raised It shows that the members of the cohort have not died from lung can- cer at an age earlier than the general population and that such an explanation cannot be offered for the absence of lung cancer in 240 men with more than 40 years of increase is particularly marked after age 50 confirming an observation previously made to the effect that until recently lung cancer has probably been underdiagnosed in the older age groups in the general popu- | employment referred to on page 643 Before leaving this comparison of the Province with the miners it should be shown that their age distributions are rea- sonably the same That this is the case can be observed from Table 19 It should be remembered that the miners retire and consequently it can be expected that the oldest age group will be larger in lation To use these figures for purposes of comparison it is necessary to combine the rates for certain age groups in order to conform to the age distributions used in this study Since the exact populations in each age group for the years indicated is not known this must be an approximation However the rates would be somewhat as the general population The data presented in Table 20 indicate that the lung cancer rate generally decreases after age 70. Therefore we could expect the rate for all people over 65 to be smaller than the rate for the group between 65 and 75 which would apply to the oldest group of miners It is felt that by using the whole adult male population we have developed rates for the gen- eral population which are somewhat lower than if we had been able to exclude the people in the general population over 75 A comparison between the asbestos miners and the population of the Dominion as a whole was made using statistical material from several sources In one source Phil- 79 lips gave Canada for 1952. The age- and specific three periods between rates for males are rates for 1931 and given in Table 20 These figures show strikingly the increase in rates between 1931 and 1952 and this follows: Age Group 20-44 45-54 55-64 65+ Rate 27 69 90-95 These rates are in general lower than those developed for the total proved and suspected cases of lung cancer among the asbestos miners The only large difference however is in the age group of 65 years and over and it is quite possible that the rate for this group may have increased for Canada between 1952 and 1954 as it did for the Province of Quebec Table 17 A further comparison has been made with an over rate obtained from the American Cancer Society for respiratory cancer deaths in Canada in 1953. This rate for males is 20.8 per 100,000 or 5 more per 100,000 than Phillips 1950-1952 rate and compares with 25.3 per 100,000 for proved cases and 33.8 per 100,000 for total cases among the 647 Braun A. M. A. ARCHIVES OF INDUSTRIAL HEALTH TABLE Number of Deaths and Death Rates per 100,000 by Age Groups for the Adult Male Population of the United States* Age Group 20-44 55-64 55-64 85+ Total Population 24,544,000 8,085,000 6,340,000 5,670,000 44,619,000 Cases 883 2,979 6.254 6.483 16,399 Rate per 100,000 3.0 36.9 98.6 114.3 37.3 Data from Vital Statistics of the United States Vol 1 and Data 1952 asbestos miners in this study It is therefore obvious that there are no important differences between the rates for asbestos miners and those for the general population of Quebec and the Dominion of Canada Since it is probable that figures for the United States are more complete and therefore possibly more comparable to the data for the miners specific rates were computed from Vital Statistics of the United States Volumes I and II for 1952. These rates have been tabulated in Table 21 It is apparent that these rates compare favorably with those for the asbestos miners as shown in Table 8. Still other rates for the United States were obtained from the American Cancer Society and for males these were 25.3 per 100,000 in 1953 and 28.0 per 100,000 in 1955. They are not identical with the rate calculated from the figures of the office of Vital Statistics but this is possibly because the American Can- cer Society rates are for males of all ages Nevertheless they too compare favorably with the rates of 25 or 34 for total cases obtaining among the asbestos miners Turning for a moment to a comparison between the asbestos miners and persons who are exposed to asbestos in one form or another as distinguished from the gen- eral population groups just discused who have no exposure an interesting observa- tion can be developed by deduction Hue- 58 per has stated that there are about 35,000 persons exposed in the United States and we have found that the Canadian mines employ about 8000. Elsewhere it has been estimated that the workers in England who have exposure total between 3000 and 5000 With workers in Africa Denmark Nor- way and other countries at least 50,000 persons must be exposed throughout the world and it can be assumed that this number has been fairly constant in the 20 years since 1935 when the first case of asbestosis with lung cancer was reported At least 1,000,000 years of exposure has thus been accumulated and this figure can be divided by the approximately 150 cases of lung cancer with asbestosis re- during the year period This ported gives a rate of 15 per 100,000 whichis at least indicative that any lung cancer rate which can be calculated for workers ex- | posed to asbestos dust is not much greater than that for the unexposed population Comparison Between Eight Counties Ad- jacent to the Producing Areas and lung Eight Selected Counties compare cancer mortality rates in the counties sur- with asbestos producing rounding the areas | another of counties in which no as-| group rates bestos miners are likely to reside the were computed on the basis of figures for | ~ the years 1950 through 1955. The eight counties selected for comparison were Ar-~ genteuil Chateaugay Montmagny Port- neuf Richlieu Riviere St. Hyacinthe and Terrebonne mainly because they represent a wide geographic distribu- tion throughout the Province The counties selected because of their proximity to the asbestos mines include Arthabaska Beauce Rich- Drummond Frontenac Megantic mond Sherbrooke and Wolfe Table22 shows the number of lung cancer deaths for the years 1950 through 1955 for each of these counties and a mortality rate based on the adult male population in 1952 To emphasize the comparison Megantic County has been shown separately as has the Province of Quebec and also the Prov- ince with the eight producing counties subtracted Because of its unique lung cancer death rate Montreal et Isle de Jesus has also been listed in order to provide further comparison It is apparent from the table that the lung cancer death rate for the eight counties Megan Eight Eight Provir Provit ad~fl Montr It R1111 duci of Wh twi cou Pro rat WOI ver 19 in un oth ex WC C01 the tie in- liv C P P t A Vol 17 June 1958 He, F INDUSTRIAL HEALTH HEALTH countries at least 50,000 e exposed throughout the an be assumed that this 1 fairly constant in the 20 5 when the first case of ung cancer was 10 years of reported exposure cumulated and this figure by the approximately 150 ancer with asbestosis re- This 's he year period 5 per 100,000 which is at hat any lung cancer rate alculated for workers ex-. . dust is not much greater ^ unexposed population - tween Eight Counties Ad- Producing Areas and unties compare lung ~ rates in the counties sur- 3 producing areas with , counties in which no as- likely to reside the rates In the basis of figures for * through 1955. The eight for comparison were Ar-;5. gay Montmagny Port- . Riviere St.-* / errebonne mainly because wide geographic * distribu- he Province The counties of their proximity to the lude Arthabaska Beauce ntenac Megantic Rich- 2. and Wolfe Table 22 r of lung cancer deaths 0 through 1955 for each 3. and a mortality rate t male population in 1952 le comparison Megantic shown separately as has Quebec and also the Prov- ght producing d Because of its unique rate Montreal et Isle de 1 listed in order to provide n from the table that the rate for the eight counties Vol 17 June 1958 LUNG CANCER IN ASBESTOS MINERS TABLE Number of Lung Cancer Deaths and Rate per 100,000 Years Counties M. antic County Right Adjacent Counties Eight Selected Counties Province of Quebec Province of Quebec less eight adjacent counties Montreal et sio de Jesus Adult Male Population 1952 1950 1951 13.100 3 } 97.600 6 3 83.000 2 10 1.198,000 198 220 1.300,000 190 217 394.000 3 7 Male Lung Cancer Deaths 1952 is A 243 236 158 1953 3 16 18 303 287 192 1954 1 + 3 303 299 185 1955 4 16 9 337 341 225 Total 13 # 19 1624 1370 770 It is assumed that all male lung cancer deaths occurred after age W. Rate per 100,000 100,000 18.9 9.4 9. 23.5 23.8 32.3 immediately surrounding the asbestos ducing areas is practically identical with that of eight counties selected for comparison While Megantic County has a rate nearly twice that of the combined eight selected counties it is lower than the rate for the Province and considerably lower than the rate for Montreal The figure for Montreal would certainly be higher except for the very low numbers of deaths reported for 1950 and 1951 and it would appear that in those years some error in reporting has undoubtedly been made On the basis of the other years 1950 and 1951 deaths would be expected to be about 200 greater This would result in a rate of 40 per 100,000 suggestive of cancer of the lung and in- cluded such diagnoses as mediastinal lymphosarcoma mesothelioma cancer of the leg with metastases to lung abscess of lung and cancer of the pancreas One other was diagnosed on the basis of ray only In addition there are now living four cases in which the diagnostic evidence is strongly suggestive of lung cancer This is a total of 33 cases of all types including 10 sus- pected but unproved cases and 4 that are still living The remaining 19 constitute the total of proved cases of cancer of the lung among the asbestos miners since 1940 The proved cases averaged 59 years of age at death and varied between 37 years The only possible conclusion from this comparison is that there is no evidence that the persons who live and work in the coun- ties surrounding and adjacent to the as- and 68 years Their working span covered periods varying from a minimum of 14 years to a maximum of 37 years Only three men had less than 25 years of em- producing areas have any greater incidence of lung cancer than those who ployment in the industry Seven among those on whom such information is avail- live elsewhere in the Province able had a weighted exposure placing them Comment on All Recorded Lung Cancer Cases Living and Dead among the Asbes- in Category III and six worked in an exposure represented by Category I. tos Although a simple enumeration of all the known or suspected cases of cancer of the lung in these areas has no particular value from a statistical point of view it is of interest to summarize such cases for the record There were nine deaths prior to the beginning of the time period covered by the study including one in which the diagnosis was mediastinal lymphosarcoma During the period covered by this There were only 17 among these proved lung cancer cases in which we have information regarding the presence of as- bestosis Asbestosis was present in nine although it was minimal in two Two pathologists disagreed regarding its presence in another At least seven of the 19 proved lung cancers therefore were not accom- panied by asbestosis investigation there were nine proved cases and three suspected cases in the cohort Through 1956 and to date in 1957 there were eight deaths six of which were merely Summary and Conclusions Interest in the question of whether there may be an association between lung cancer 649 Braun eo A. M. A. ARCHIVES OF INDUSTRIAL HEALTH and exposure to asbestos has been evident since the report in 1935 by Lynch and Smith of a case in which lung cancer and asbes- tosis were both present As additional cases in which the two diseases coexisted were reported a causal association appears to have been gradually accepted by many authors although some workers considered the correlation to be inconclusive The pres- ent study was undertaken in an effort to de- termine whether a causal relationship did in fact exist between exposure to asbestos and cancer of the lung Since most earlier studies had been limited to enumerating the lung cancers found in certain selected samples such as cases coming to autopsy or death certificates in which asbestosis was mentioned it was apparent that they could not fulfill the re- quirements of an epidemiological and statistical approach to the problem The present study was therefore designed to meet the requirements of this method After a preliminary survey to explore the availability of reliable information data were gathered on workers in the asbestos mines in Quebec based on their medical records A cohort was defined as a group ofasbestos miners having at least five years of exposure and who were in the industry in 1950. Data relative to their characteristics were collected and their status at the end of a year period of observation was de- termined In the case of those who had died an exhaustive search of death certif- icates 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 collected in the appropriate places Comparisons of the rates obtained for asbestos workers and for the other popu- lation groups were made according to ac- cepted statistical methods Records were obtained on 6091 persons who fulfilled the criteria of the cohort It 650 was not possible to trace 133 of these for remaining the whole period but 5771 of the 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 9 and to be strongly suggested in 3 The members of the cohort were studied | with respect to age length of employment | a weighted average of their exposure and their smoking habits * It was found that 4673 were smokers within the definition of that term as used in this study Thirty per cent of the cohort were more than 45 years of age and thirty per cent had been employed for longer than 20 years Thirty per cent had a weighted exposure which placed them in the category of highest ex- . posure The mortality rate for lung cancer as - computed on the basis of nine proved . deaths among the cohort was 25.3 per 100 = 000. When the three suspected cases were added the total rate for the cohort rose * to 33.8 The importance of the as suspected + but unproved cases in these determining rates has been reiterated because it is likely * that such cases would not be included in - the statistics for the general population and because they influence the results so mark- edly According to the findings in this study the mortality rate from lung cancer does not appear to increase with length of exposure or with degree of exposure a fact which presents strong evidence against the carcinogenicity of asbestos Comparison of the experience among the asbestos miners with that of various seg- ments of the unexposed comparabie popu- lation shows that the observed number of deaths among the miners is not significantly greater than the expected number The rate for proved cases among the asbestos miners 25.3 per 100,000 compares well with the rate of 22.5 per 100,000 for the rest of the Province and 20.8 per 100,000 for adult males throughout the Dominion of Canada It also compares satisfactorily with rates ' Vol 17 June 1958 OF INDUSTRIAI HEALTH HEALTH LUNG CANCER IN ASBESTOS MINERS these e to trace 133 of 1. but 5771 of the remainingremaining ad to be still living living in 1953 je 187 known dead been is considered to have ed in 9 and to be strongly of the cohort were studied studied age length of employment age of their exposure : F of 37.2 25.3 and 28.0 obtained from various F sources for adult males in the United States Finally in this matter of comparison it : would appear that the world experience of persons exposed to asbestos dust is not worse with respect to lung cancer than that of the unexposed population The counties surrounding the asbestos- producing areas in which it is presumed most of the asbestos miners live have al- within ers within the definition of :: than I in this study Thirty cohort were more 45 d thirty per cent had been nger than 20 years Thirty which weighted exposure x he category of highest ex- .; QmEost identical mortality rates with those of eight counties widely scattered through the Province and are lower than those for the remainder of the Province and much lower than the rate for Montreal Since 1940 there have been 19 cases in which the diagnosis of primary cancer of the lung may be considered to have been rate for lung cancer as = : basis of nine proved *: 100 : cohort was 25.3 per _ ree suspected cases were rate for the cohort rose portance of the suspectedses in determining thes<e5 terated because it is likely vould not be included in he general population and ence the results so mark- - proved Approximately half of these cases were associated with asbestosis All but one died in the recognized cancer and at least third had only the lightest exposure Category ) to asbestos dust On the basis of what are believed to be complete and reliable data it seems fair to conclude that the asbestos miners in the Province of Quebec do not have a significantly higher death rate from lung cancer than do comparable segments of the general population Furthermore the death rate from lung e findings in this study from lung cancer does rease with length of ex- gree of exposure a fact ong evidence against the asbestos he experience among the ith that of various seg- posed comparable poputhe observed number of cancer in the areas contiguous to the asbestos operations is comparable to that in areas widely scattered throughout the Province of Quebec and is lower than in some urban- ized areas within the Province REFERENCES 1. Alascio Escobar .: Bronchial Carcinoma Review of 200 Cases J. Internat Coil Surgeons 25 375-379 Sept. 1956 2. Allen M. .: Bronchiogenic Carcinoma As- iners is not significantly pected number The rate nong the asbestos miners compares well with the sociated with Pneumonoconiosis Report of 2 Cases J. Indust Hyg 346-347 Nov. 1934 3. Cartier .: A Contribution to the Study of Asbestosis Arch mal profess 589-595 1949 0,000 for the rest of the 4. Anderson C. S. and Dible J. H Silicosis per 100,000 for adult le Dominion of Canada atisfactorily with rates and Carcinoma of the Lung J. Hyg 185-204 March 1938 5. Baader E. W Asbestosis Deutsche med Wehnschr 65 407-408 March 17 1939 6. Behrens Wi Experimental Asbestosis Schweiz Ztschr allg Path 275-297 1931 7. Behrens W. Jr The Clinical Picture and Pathology of Asbestosis Ztschr Unfallmed u Berufskrankh 129-140 June 15 1952 8. Berblinger W Increase of Lung Cancer and Diseases Due to Dust Inhalation Med Klin 27 1337-1342 Sept. 11 1931 9. Berenblum .: Irritation and Carcinogenesis Arch Path 233-244 Oct. 1944 10. Bohne Asbestosis Deutsche med Wchnschr 62 928-930 June 5 1936 11. Bohme A Results of Periodical Examinations of Workers in an Asbestos Factory Beitr Silikose Forsch 11:34 1951 12. Bowles O Asbestos Marketing and Fabrication Information Circular No. 6869 U. S. Department of the Interior Bureau of Mines 1935 pp 1-26 13. Breslow .; Hoaglin .; Rasmussen G. and Abrams H. .: Occupations and Cigarette Smoking as Factors in Lung Cancer Am J. Pub Health 171-181 Feb. 1954 14. Bristol L. .: Roentgenologic Aspects of Silicosis and Asbestosis M. A. Arch Indust Health 189-195 March 1955 15. Cancer of the Lung An Evaluation of the Problem Proceedings of the Scientific Section Annual Meeting American Cancer Society Inc. Nov. 3-4 1953 New York American Cancer Society Inc. 1956 16. Cartier .: Asbestosis Cancer of the Lung in discussion on Smith W. E Survey of Some Current British and European Studies of Occupational Tumor Problems A. M. Arch Indust Hyg 262-263 1952 17. Cartier .: Some Clinical Observations of Asbestosis in Mine and Mill Workers A. M. A. Arch Indust Health 204-207 March 1955 18. Clerens .: Research into Pulmonary Asbestosis in Belgium Arch belges m^'dSociale 557565 Nov. 1951 19. Clynes Asbestosis and Silicosis Brit M. J. 379 1931 20. Coffin G. .; Duryee H. .; Maier H. .; Pardee H. E. B. and Wynter E. .: The Effects of Tobacco Smoking Panel Meeting Bull New York Acad Med 133-156 Feb. 1956 21. Cohart E. M Lung Cancer and Economic Status Cancer 1126-1129 Nov. 1955 22. Cooke W. .: Pulmonary Asbestosis Brit M. J. 1024-1025 Dec. 3 1927 23. Cureton R. J. R Squamous Cell Carcinoma - Occurring in Asbestosis of the Lung Brit J. Cancer 249-253 Sept. 1948 24. Cutler S. .; Schneiderman M. A. and Greenhouse S. W Some Statistical Considera- Vol 17 June 1958 Truan 651 M. A. ARCHIVES OF INDUSTRIAL HEALTH tions in the Study of Cancer in Industry Am J. Pub Health 1159-1166 Sept. 1954 25. Davies D. .: Current Status of Lung Cancer Research Some Pathogenetic Aspects CA 169-174 Sept. 1956 26. Desmeules .; Rousseau .; Giroux M. and Sirois A Asbestosis and Pulmonary Cancer Semaine de h^p Paris 1820-1823 Aug. 7 1947 27. Doll .: Bronchial Carcinoma Incidence and Aetiology Milroy Lectures abridged Brit M. J. 521-527 Sept. 5 585-590 Sept. 12 1953 28. Doll .: Among Asbestos 12 81-86 1955 Mortality Workers from Lung Cancer Brit J. Indust Med 29. Donnelly .: Pulmonary Asbestosis Am J. Pub Health 1275-1281 Dec. 1933 30. Dorn H. F. and Cutler S. .: Morbidity from Cancer in the United States Pub Health Monograph No. 29 P. H. S. Publication No. 418 U. S. Public Health Service 1955 121 pp 31. Dorn H. F Cancer Morbidity Surveys A Tool for Testing Theories of Cancer Etiology Am J. Pub Health 45 615-621 May 1955 32. Egbert D. S. and Geiger A. .: Pulmonary Asbestosis and Carcinoma Report of a Case with Necropsy Findings Am Rev. Tuberc 143-150 July 1936 co 33. Ellman .: Pulmonary Asbestosis Its Clinical Radiological and Pathological Features and Associated Risk of Tuberculosis Infection J. Indust Hyg 165-183 July 1933 34. Ellman P Pulmonary Asbestosis Proc Roy Soc Med 557 July 1941 35. Feil .: Pneumoconiosis in Asbestos Workers Presse m^'d 1872-1874 Dec. 19 1931 36. Fulton W. .; Dooley .; Matthews J. L. and Houtz R. .: Asbestosis Part III The Effects of Exposure to Dust Encountered in Asbestos Fabricating Plants on the Health of a Group of Workers Special Bulletin No. 42 Pennsylvania Department of Labor and Industry Bureau of Indust Standards Sept. 20 1935 37. Gardner L. U. and Cummings D. .: Studies on Experimental Pneumoconiosis Inhala- tion of Asbestos Dust Its Effect upon Tuberculous Infection J. Indust Hyg Feb.; 97 March 1931 Primary 65-81 38. Gilliam A. G Mortality Trends in Lung Cancer Cancer 1130-1136 Nov. 1955 39. Gilliam A. G Mortality Attributed to Lung Cancer in the Large Cities of the United States in 1948 and 1949 J. Nat Cancer Inst 15 1307-1312 1955 40. Gloyne S. .: Two Cases of Squamous Carcinoma of the Lung Occurring in Asbestosis Tubercle 17 5-10 Oct. 1935 652 41. Gloyne S. R Pneumoconiosis A Histological Survey of Necropsy Material in 1205 Cases Lancet 810-814 April 14 1951 42. Gloyne S. .: A Case of Oat Car- cinoma of the Lung Occurring in Asbestosis Tubercle 100-101 Dec. 1936 43. Gloyne S. R. and Merewether E. R. .: Asbestos Occupation and Health Supplement to x Encyclopedia on Occupation and Health Geneva International Labor Office 1938 wn 44. Goldblatt M. W. and Goldblatt .: dustrial Carcinogenesis and Toxicology in In- #; In- 3 In- dustrial Medicine and Hygiene edited by E. R. Merewether London London Butterworth Co. Ltd. 1956 Vol 3 pp 185-188 & *e 45. Haenszel W. M Epidemiological Tests of RNe Theories on Lung Cancer Etiology Pub Health SS Rep 163-172 Feb. 1956 : 46. Hammond E. .: Lung Cancer and Com- mon Inhalants Cancer 1100-1108 ( Nov. 1954 47. Hammond E. .: Etiology of Bronchiogenic Carcinoma CA 156-168 Sept. 1956 48. Holleb H. B. and Angrist A Bronchio- genic Carcinoma in Association with Pulmonary Asbestosis Report of 2 Cases Am J. Path 18 123-135 Jan 1942 % aid % 3 gin nd v7 4 Pulmonary 49. Homburger .: Primary Carcinoma of The Incidence of Lungs and Pulmonary Asbestosis Analysis of Literature and Report Re of 2 Cases Am J. Path 797-807 Sept. 1943Report 50. Horn D Is Lung Cancer on the Increase Evaluation of Present Day Evidence Cancer of the Lung Proceedings of the Scientific Section Annual Meeting American Cancer Society Inc. Metbe Nov. 3-4 1953 51. Hornig F Clinical Considerations on the Question of Industrial Cancer of Asbestos Work- ers Ztschr Krebsforsch 47 281-287 1938 52. Hueper W. .: Cancer in Its Relation to Occupation and Environment Bull Am Soc Control Cancer 25 63-69 June 1943 53. Hueper W. C Significance of Industriai Cancer in the Problem of Cancer Occup Med 190-200 Sept. 1946 54. Hueper W. C Environmental and Occupa- tional Cancer Public Health Service Supp 20" U. S. Public Health Service 1949 55. Hueper W. C A Methodology for Environmental and Occupational Cancer Surveys Public Health Monograph No. 1 P. H. S. Publication No. 12 U. S. Public Health Service 1950 56. Hueper W. .: Environmental Lung Cancer Indust Med 49-62 Feb. 1951 57. Hueper W. C Occupational and Environ- mental Pulmonary Cancers with Special Reference to Pneumoconiosis Proceedings 7th Saranac Symposium on Pneumoconiosis 1952 58. Hueper W. .: A Quest into the Environ- mental Causes of Cancer of the Lung Pub Vol 17 June 1953 OF INDUSTRIAL HEALTH Pneumoconiosis: .: Vecropsy A Histo Histo : A Cases Vecropsy Material in 1205 April 14 1951 Cases R. A Case of ung Occurring " Dec. 1936 Oat Car- in AsbestosisAsbestosis 1. and Merewether E. R. Ai and to Ocupation Health Supplement Occupation and Health Geneva - Office 1938 Geneva In- . W. and Goldblatt .: nesis and Toxicology in In- A ad Hygiene edited by E. R. on London Butterworth & pp 185-188 & Cancer ofwe Epidemiological Tests fi Cancer Etiology Pub Health Health eb 1956 - C. Lung Cancer and #: f> ee Com-aed cer 1100-1108 Nov. 19524 .: Etiology of Bronchiogenic 156-168 Sept. 1956 oft and Angrist A Bronchio- ~, | Association with Pulmonary 2 of 18 2 Cases Am J. Path 9 %: .: The Incidence of 1 of Lungs and Pulmonarys of Literature and Report & Path 797-807 Sept. 1943 nt Day Evidence Cancer of 7 ags of the Scientific Section ~ nerican Cancer Society Inc. ~ linical Considerations on the *: al Cancer of Asbestos Work- : rsch 281-287 1938 : Cancer in Its sironment Bull 69 June 1943 Relation to Am Soc : Significance of Industriai m of Cancer Occup Med 16 Environmental and Occupa Health Service Supp 20" Service 1949 A Methodology for Environ- nal Cancer Surveys Public la 1. P. H. S. Publication Health Service 1950 .: Environmental Lung 49-62 Feb. 1951 Occupational and Environcers with Special Reference Proceedings 7th = Saranac toconiosis 1952 A Quest into the Environ- ancer of the Lung Pub Vol 17 June 1953 LUNG CANCER IN ASBESTOS MINERS Health Monograph No. 36 P. H. S. Publication No. 452 U. S. Public Health Service 1955 30. Hueper W. .: Environmental Causes of Cancer of the Lung other than Tobacco Smoke Dis Chest 141-158 Aug. 1956 60 Isselbacher K. .; Klaus H. and Hardy H. .: Asbestosis and Bronchogenic Carcinoma Report of One Autopsied Case and Review of Available Literature Am J. Med 721-732 Nov. 1953 61. Kennaway E. L. and Kennaway N. M A Study of the Incidence of Cancer of the Lung and Larynx J. Hyg 236-267 June 1936 62. Kennaway E. L. and Kennaway N. M Studies of Incidence of Cancer of the Lung and Larynx Brit J. Cancer 153-158 June 1951 63. Klotz M. .: Association of Silicosis and Carcinoma of the Lung Am J. Cancer 35 38-49 Jan. 1939 64. Lanza A. .; McConnell W. J. and Fehnel J. W. The Effects of the Inhalation of Asbestos Dust on the Lungs of Asbestos Workers Preliminary Study Pub Health Rep 1-12 Jan. 4 1935 65. Lanza A. J. editor Silicosis and Asbestosis New York and London Oxford University Press 1938 66. Lew E. .: Use of Life Insurance Company Records for Cancer Studies A. M. Arch Indust Hyg 198-203 March 1952 67. Linzbach A. J. and Wedler H. W Occupational Cancer among Asbestos Workers Arch path Anat 307 387-409 1941 68. Lynch K. M. and Smith W. A Pulmonary Asbestosis Carcinoma of Lung in Silicosis Am J. Cancer 56-64 May 1935 69. Lynch K. M. and Smith W. A Pulmonary Asbestosis A Report of Bronchial Carcinoma and Epithelial Metaplasia Am J. Cancer 36 567-573 Aug. 1939 70. Lynch K. M. and Cannon W. M Asbestosis Analysis of 40 Necropsied Cases Dis Chest 874-889 Nov. 1948 71. McPheeters S. .: A Survey of a Group of Employees Exposed to Asbestos Dust J. Indust Hyg 229-239 April 1936 72. Merewether E. R. .: The Occurrence of Pulmonary Fibrosis and Other Pulmonary Affections in Asbestos Workers J. Indust Hyg 12 198 May 239 June 1930 73. Merewether E. R. A. and Price C. W Report on Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos Industry London His Majesty's Stationery Office 1930 74. Merewether E. Asbestosis Tubercle 152 Jan. 1934 R. A A Memorandum on 109 Dec. 1933 15 Truan 75. Merewether E. R. A Annual Reports of the Chief Inspector of Factories London His Majesty's Stationery Office 1947 76. Merewether E. R. A. editor Industrial Medicine and Hygiene London Butterworth & Co. Ltd 1956. Vol 3 77. Nordmann M The Industrial Cancer of Workers in Asbestos Ztschr Krebsforch 47 288302 1938 78. Nordmann M. and Sorge A Cancer Produced by Asbestos Dust mental Animals Ztschr Krebsforch Pulmonary in Experi51 168-182 1941 79. Phillips A. .: Mortality from Cancer of the Lung in Canada 1931-1952 Canad M. A. J. 71 242-244 Sept. 1954 80. Saupe E Further Contributions to the Roentgenological Diagnosis of Asbestosis Arch Gewerbepath u Gewerbehyg 391-406 1939 81. Smith K. W Pulmonary Disability in Asbestos Workers A. M. Arch Indust Health 198-203 Aug. 1955 82. Smith L. W Pneumoconiosis and Lung Cancer with Special Reference to Silicosis and Asbestosis Compens Med 3-10 Nov. 1949 83. Smith W. .: Survey of Some Current British and European Studies of Occupational Tumor Problems Part III Asbestos M. A. Arch Indust Hyg 242-263 March 1952 84. Stoll R Bass R. and Angrist A Asbestosis Associated with Bronchogenic Carcinoma M. Arch Int Med 831-834 Dec. 1951 85. Teleky .: Occupational Lung Cancer Acta Union internat contre Cancer 253-273 1938 also Zentralbl Gewerbehyg 27:33 1940 86. Vorwald A. .; Durkan T. M. and Pratt P. .: Experimental Studies of Asbestosis A. M. Arch Indust Hyg 1-43 Jan. 1951 87. Wedler H. W Asbestosis and Lung Cancer Deutsche Aug. 6 1943 med Wchnschr 60 575-576 88. Wegelius .: Changes in the Lungs in 126 Cases of Asbestosis Observed in Finland Acta radiol 28 139-152 1947 89. Werber M Pulmonary Asbestosis Associated with Carcinoma Zentralbl Arbeitsmed u Arbeitsschutz 179-180 Nov. 1952 90. Wood W. B. and Gloyne S. .: Pulmonary Asbestosis Complicated by Pulmonary Tuberculosis Lancet 954-956 Oct. 31 1931 91. Wyers H Asbestosis Postgrad Med 25 631-638 Dec. 1949 92. Wynder E. L. and Graham E. .: Etiologic Factors in Bronchiogenic Carcinoma with Special Reference to Industrial Exposures Report of 857 Proved Cases A. M. Arch Indust Hyg 221-235 Sept. 1951 653 VOLUME 17 JUNE 1958 NUMBER 6 INDUSTRIAL HEALTH INDEX NUMBER Covel Covel Mutual Goals of Public Health and Occupational Medicine L. E. Burney New Techniques in Teaching Occupational Medicine Jean Spencer Felton Significance of the 1956 Social Security Amendments to the Insurance Business Practical Psychiatry in Industry R. H. Felix ~ Practical Application of Psychiatric Techniques in Industry Ralph T. Collins Potassium Alloy . Asher J. Finkel and Willard B. Lyons John H. Miller The Reconciliation of Pensions and Social Security Disability Insurance Robert E. Royes Occupational Medicine and Modern ; Drugs Albert H. Holland Jr. v An Epidemiological StudyStudy of LungLung Cancer in Asbestos Miners Daniel C. Braun and T. David Truan / Collection of Integrated Samples of Gaseous Effluents Richard S. Brief and Philip A. Drinker . Practical Significance to Industry of Recent Developments in Tuberculosis Management Edward T. Blomquist Industrial Health in the Atomic Energy Industry James H. Sterner Executive Health Examinations Robert Clyne Tellurium Oxide Marvin L. Amdur Practical Aspects of a Hearing Conservation Program Lloyd B. Shone News and Comment Books AMERICAN MEDICAL ASSOCIATION PUBLICATION