Document ZnV2b92DrJx7yakMbKy2gV9aL

FILE NAME Cape Asbestos CAPE DATE 1955 DOC CAPE152 DOCUMENT DESCRIPTION Journal Article - Mortality from Lung Cancer in Asbestos Workers Legal - Tibbs Case Exhibit 50 Brit J. industr Med 1955 12 81 ELCTRONIAY MORTALITY FROM LUNG CANCER IN ASBESTOS WORKERS FILED - BY RICHARD DOLL 2023 From the Statistical Research Unit Medical Research Council London Oct RECEIVED FOR Publication AUGUST 10 1954. 18 12:13 Sixty cases of lung cancer have been recorded in persons with asbestosis Boemke 1953 ; Hueper Hueper 1952 consider that a causal relationship between asbestosis and lung cancer is either proved PM 1952 since Lynch and Smith 1935 reported the first case In view of the infrequency of asbestosis or is highly probable and the reality of the relationship was agreed at the recent International Sym- - this large number of cases suggests does not posium on the Endemiology of Lung Cancer prove lung cancer is an occupational hazard Council of the International Organizations of RICHLAND of asbestos workers The strongest evidence that it may be a hazard has been produced by Merewether and by Gloyne Merewether 1949 found that lung cancer was reported at necropsy in 13-2 of cases Medical Sciences 1953 A minority however remains sceptical Cartier 1952 Warren 1948 and according to Hueper 1952 Lanza and Vorwald so that it was thought desirable to undertake a - of asbestosis 31 out of 235 but in only 1.3 of fresh investigation cases of silicosis 91 out of 6,884 and Gloyne 1951 COM ON on personal examination found lung cancer in 14.1 of necropsies on subjects with asbestosis 17 out of 121 against 6-9 in silicotics 55 out of 796 Necropsy Data Since 1935 records have been collected of all the coroners necropsies on persons known to have Neither author gave full details of the sex compo- been employed at a large asbestos works Patho- sition of the groups examined but since women logical diagnoses in 105 consecutive cases are PLEAS PLEAS form a higher proportion of asbestos workers than summarized in Table 1. Details of the cases in of persons employed in occupations liable to give TABLE 1 - rise to silicosis miners stonemasons pottery CAUSES OF DEATH DIAGNOSED AT NECROPSY AMONG workers foundrymen metal grinders and since lung PERSONS EMPLOYED AT AN ASBESTOS WORKS 1933-52 cancer is less common among women the differences in the proportions of cancer cases cannot be Cause of Death i Asbestosis | Asbestosis | Present Absent All Cases ee ee accounted for by differences in sex distribution In Heart failure " 34 45 fact the proportions which are more properly com- Pulmonary tuberculosis -- 12 ' 9 21 203CP41759 parable with the findings in silicotic subjects are the proportions of lung cancer found among men with asbestosis 17.2 in Merewether's series and 19-6 in Gloyne's Animal experiments are inconclusive A positive result was reported by Nordmann and Sorge 1941 who found that of 10 mice which had been exposed to asbestos dust and survived for 240 days two developed lung carcinoma Smith 1952 however 66 considers that one of the carcinomas was in fact an example of squamous metaplasia and that the other an adenocarcinoma may have developed spontaneously from the common mouse adenoma Lung cancer . respiratory respiratory 15 Other diseases of the respiratory system .- oe bee 10 Other diseases .. . i 4 3 18 : 4 14 3 | 7 All causes : 75 | 30 | 105 which lung cancer was found are shown in Table 2 During the first half of the period eight deaths occurred in which lung cancer was found in asso- ciation with asbestosis while in the second half of the period there were seven such cases and a further three in which lung cancer was found without asbestosis The number of asbestos workers employed at the works increased steadily from 1914 A negative result has been reported by Vorwald and Karr 1938 The majority of workers cited by * Necropsies on asbestos workers are ordered by the coroner when in his opinion there may be a question of asbestosis being a contri- butory cause of death 81 82 BRITISH Journal of industrial mediCINE TABLE 2 OCCUPATIONAL HISTORY AND NECROPSY DATA OF ASBESTOS WORKERS WITH PRIMARY LUNG CANCER i Year Ocupation Period Exposure ELCTRONIAY of Death | Sex and Age Occupation | | FILED 1935 | M. Weaver of Exposure | Years of Years of | before Years from First | Exposure Jan. , | Exposure 1933 to Death 1919-32 : 13 13 16 Years from Last Exposure ExposurExposure e to Death | Pathological Report Asbestosis HistologicalHistologHistoliogical cal TyTyppee of Primary Lung Cancer +6 3 Present Carcinoma 1935 M. 54 1936 M. 65 1938 | M. Weaver Fiberizer Weaver 1909-32 23 23 26 3 " Epithelial carcinoma - | 1913-36 : 23 19 23 Less than 1 Endothelioma of pleura 1920-37 1920-37 2023 28 . 19 14 1 " +3 " Carcinoma 1919-39 Oct 1939 | M. Disintegrater 66 " : 24 17 29 Less than 1 " Carcinoma ( 1911-15 Disintegrater i || 1923 319923 39 | 18 1940 | M. 5 Disintegrater " 2222222229N 15 29 | Less than 1 " Carcinoma 1923 39 | ! 1941 M. | Weaver 1924-38 2222222229N 14 28 3 " celled carcinoma | 1942 M. | Bag carrier 1948 | M. | Weaver 1948 | M. 53 Weaver 1913-41 2222222229N 19 29 1 " celled carcinoma 1918 48 | 12:13 2222222229N 16 36 | than 1 " Anaplastic carcinoma PM " " 1922-35 2222222229N 10 26 13 " Carcinoma - 1948 | M. Spinner 1922-48 45 " : 2222222229N 10 26 Less than 1 " Carcinoma 1948 | M. Maintenance man | 1919-48 2222222229N 13 29 Less than 1 E3 celled carcinoma | RICHLAND 1950 F. 51 Spinner 1915-42 2222222229N 17 35 8 " Carcinoma " 1951 M. 74 Fiberizer 1917-43 2222222229N 15 34 " Adenocarcinoma 1951 | M. | Weaver 1929-50 2222222229N 9 32 1 " " Carcinoma - 1944 | M. 36 1951 M. 43 1952 | M. Weaver Fiberizer Weaver 1942-44 | 1939-48 1945-52 || | COMON 1945-52 2 12 T 11 | Also pulmonary tuberculosis than , Absent 3 " Less than 1 celled carcinoma Anaplastic carcinoma " Carcinoma " PLEAS PLEAS and a great increase in the number of lung cancer Method of Estimation of Risk deaths was also recorded among the whole popu- Although the necropsy data shown in Tables 1 - lation of England and Wales over the same period and 2 suggest 1 that some groups of asbestos It might therefore have been anticipated that a workers have suffered an increased risk of lung larger number of cases in which the two conditions cancer and 2 that the risk may now have decreased were associated would have been found in the last it is not possible to be certain of either of these CASE 10 years National regulations for the control of propositions without a more detailed knowledge of asbestos dust were however introduced in 1931 the whole mortality experience of the workers The Asbestos Industry Regulations 1931 and the first proposition has therefore been tested by 2023CP4001759 precautions taken to prevent dust dissemination in comparing the mortality experienced by that section the works had become effective by the end of the of the male employees of the works referred to following year All the subjects in whom the two above who had worked for at least 20 years in 203CP41759 diseases were found together had been employed " scheduled areas * with the mortality recorded for for at least nine years under the old conditions and all men in England and Wales and the second although 11 of the 15 men and women died within 30 years of their first exposure the association of the two conditions has not yet been found in any person taken into employment during the last 31 proposition by comparing the incidence of lung cancer among men employed for different periods under the 1933 conditions The investigation was limited to the small group of men who had been years 1923-53 It is therefore possible that the employed for at least 20 years since the labour reason more cases were not found in the second half of the period is that reduced exposure to dust has involved in searching out the individual records of already begun to lessen the incidence and severity of asbestosis * By scheduled areas is meant those areas where processes were carried on which were scheduled under the Asbestos Industry Regulations of 1931 as being dusty LUNG CANCER IN ASBESTOS WORKERS 83 ELCTRONIAY men employed for shorter periods would be dis- proportionately great and so far as was known from Table 2 would be comparatively unrewarding The date of birth date of completing 20 years " work in the scheduled areas " and where applic- England and Wales aged 55 to 59 in 1951 was 2-778 per 1,000 The numbers of years lived in this age group in the five years 1949-53 were respectively 15 years 15 years 17 years 19 years and 19 years The number of deaths expected in the period was able date of ceasing employment and date and cause therefore estimated to be 15 + 15 +17 +19 + FILED of death were obtained for each man from the records of the firm's Personnel Officer Full details 19 ^ 1,000 = 0.238 The total number of deaths expected from each category of diseases was - were in most instances already available for the men obtained by adding the numbers thus calculated for who had ceased employment as well as for the greater number who continued to be employed since some each age group for each of the five periods The great majority of the men lived and when they 2023 Oct of those who had left were registered as having asbestosis and the attention of the firm had been died died in the town in which the works was situated so that it would have been preferable to drawn to the death of others in view of the have based the calculation of the expected deaths on 18 possibility of the cause of death being industrial in the death rates observed in that town rather than on origin All the remaining men were successfully traced and the relevant details obtained This was the rates for all England and Wales These however were not known in sufficient detail Little error in 12:13 PM not difficult since by limiting the study to men who had been employed in one place for 20 years few the expected number of deaths from lung cancer is likely to have been introduced on this account since - were found to have changed their job or to have according to Stocks 1952 the adjusted death moved out of the region rate for lung cancer among men in the town con- RICHLAND From the data the numbers of men alive in each year age group were counted separately for each of the years from 1922 the first in which a man was recorded as having had 20 years service to 1953. A cerned was 96 of the rate for England and Wales Stocks's figure was calculated only for the period 1946-49 but the proportion is unlikely to have varied greatly over the longer period of the investi- - man who had completed the 20 years before the begin- gation The expected number of deaths from all ning of a year and who was alive at the end of it was causes is however likely to be somewhat under- COM ON counted for that year as one unit a man who estimated since the adjusted death rate from all completed the period before the beginning of a year causes for the town is about 25 higher than the but who died during it and a man who completed the England and Wales rate i.e. the excess was 22 in period during a year and who survived to the end of 1950 % in 1951 and 22 in 1952 it were each counted for that year as half a unit the PLEAS PLEAS one man who died the same year as he completed his Results the year period was counted as a quarter of a unit The number of men studied was 113 ; numbers - The causes of death were recorded as they were of years lived in each of the five periods in each given on the death certificate or when available as age group are shown in Table 3. The total number they were finally determined by necropsy The causes TABLE 3 were classified in five categories see Table 4 and the numbers in each category were then compared with NUMBER OF YEARS LIVED BY MEN WITH 20 OR MORE YEARS OF WORK IN A SCHEDULED AREA | | | | 203CP41759 those which might have been expected to occur by multiplying the numbers of men alive in each fiveyear age group by the corresponding mortality rates for men in England and Wales over the same period Because of the small numbers however the populations were not considered separately for each year Age | years | 19341934 Period 33819839 431944 481949 All Periods 53 30- CO o ! 0-5 1.5 0 0 2 35- | 40- | 45- 50- 4.5 9.5 95) 6-5 2 16 19-5 | | 25-5 11 33.5 50 39.5 17.5 48 78.5 85 9 55 84 96.5 | 44 162 241-5 253 but were added together to form five groups living 55 60- . If | 6 30 3 + 5.25 52 25-5 85.5 36 185-5 84-75 in the periods 1922-33 1934-38 1939-43 1944-48 and 1949-53 and the mortality rates used for each 657075-79 i 13.5 3 | 0 oo; 2 0 | 9 1 10 3 1.5 | 21-5 3.5 0.5 49 17.5 3 group were those for the years 1931 1936 1941 1946 and 1951. The rates for 1931 were used for the ages 58 | 88 | 183-75 321 | 391.5 | 1042-25 period 1922 3r3ather than those for the years of deaths from all causes and the number of deaths since disproportionately few men were under observed in each of the five disease categories observation during the early part of the period As together with the expected number of deaths are an example of the method the mortality rate for all shown in Table 4. From Table 4 it appears that the neoplasms other than lung cancer among men in men who had been exposed to asbestos dust suffered 84 BRITISH Journal of Industrial medicine ELCTRONIAY TABLE 4 CAUSES OF DEATH AMONG MALE ASBESTOS WORKERS COMPARED WITH MORTALITY EXPERIENCE OF ALL MEN IN ENGLAND AND WALES No. of Deaths Test of the increase in mortality attributed to lung cancer over the past 30 years is certainly due to improvements in diagnosis and in therapy Doll 1953 Even however if it were postulated that the whole of the recorded increase between 1931 and 1951 was _ _ - -] Significance Cause of Death Expected of spurious and that the real mortality from the disease Difference No. on England between Observed throughout was that ascribed to it in 1951 the Expected FILED Observed and expected number of deaths is increased to only 1.1 Wales Expected - Value Rates of P and the observed excess is still grossly significant | | ' 2023 Lung cancer : with mention of asbestosis 11 without mention of asbestosis 0 For the actual number of lung cancer cases to be so PALLON 000001 little in excess of the expected as to be reasonably 0-8 Other respiratory diseases including pulmonary tuberculosis and Oct attributable to chance it would be necessary for the expected cases to be 6-2 that is 5-6 times the number cardiovascular diseases: 18 with mention of asbestosis .. 14 \ without mention of asbestosis 46 = 7.6 | 0.001 estimated on 1951 rates In other words it would be necessary to postulate that in 1951 and throughout lung Neoplasms other than All other diseases. cancer . . 4 2.3 4 4.7 | > 0.1 the previous 20 years there was 5.6 times as much cancer of the lung as was recognized in 1931 12:13 causes .. 0. 0... 39 15-4 0.000001 which would mean that the condition would have | | PM * to have been present and capable of detection in Including one case with pulmonary tuberculosis - Including two cases benign stricture of oesophagus and septi- over 20 of all men at death Moreover even if caemia in which asbestosis was present but was not thought to this were so it would still not account for the fact have been a contributory cause of death that all the cases of lung cancer were found in RICHLAND an increased mortality from lung cancer other respiratory diseases and cardiovascular diseases in association with asbestosis but that their mortality association with asbestosis It is therefore concluded that the fourth explan- ation is the most reasonable one and that the asbestos from other diseases was close to that expected - workers who had worked for 20 or more years in the Four explanations of the findings are possible: 46 scheduled areas suffered a notably higher risk COM ON 1 that all the men who had died of lung cancer were recorded because of interest in the condition but that some of the records of other men dying of other diseases or still alive were omitted with consequent from lung cancer than the rest of the population To test if the risk has altered since the 1931 regulations were introduced it is not only necessary to make allowance for duration of employment underestimation of the expected number of deaths ; before the end of 1932 but also to allow for the men's PLEAS PLEAS 2 that lung cancer was incorrectly and excessively diagnosed among the asbestos workers 3 that ages and for the total durations of their employment in the scheduled areas " since the men employed - lung cancer was insufficiently diagnosed among the in the earlier periods can also have been employed general population of England and Wales or 4 longer and lived to be older On the other hand that the asbestos workers studied suffered an excess there is no need to consider the changing incidence mortality from lung cancer of lung cancer in the total population of England and It certainly cannot be claimed that the records of Wales since the industrial risk has been shown the Personnel Office were necessarily complete but to be small in comparison with the industrial one they were believed to be complete and no deficiency The data required for comparing the risks among men 203CP41759 on this score would account for the total excess of deaths unless it were so gross that more than half the defined population had been omitted Moreover the number of deaths due to conditions unrelated to asbestosis was close to the estimated number and this employed for under 10 years for 10 to 14 years and for 15 years and over in the 1933 conditions are shown in Table 5. The ages shown are the ages at death of the men who have died and the ages in mid- 1953 for the men who are still alive The expected is unlikely to have happened unless the population numbers of men in each 1933 employment group had been estimated approximately correctly and the found to have asbestosis or asbestosis and lung deaths from all causes fully reported cancer are estimated by multiplying the numbers in All the 11 deaths attributed to lung cancer were each age total employment and 1933 employ- confirmed by necropsy and histological examination ment subgroup by the proportions of men with so that the excess number cannot be attributed to asbestosis or with asbestosis and lung cancer in the incorrect diagnosis among the group of asbestos same age and total employment group for all lengths workers Some of the excess may well be due to an of 1933 employment combined For example underestimation of the expected deaths since part of three out of the nine men aged 50 to 54 years who had LUNG CANCer in asbESTOS WORKERS 85 ELCTRONIAY TABLE 5 NUMBERS OF MEN EMPLOYED FOR DIFFERENT PERIODS BEFORE 1933 AND NUMBERS KNOWN TO HAVE ASBESTOSIS AND LUNG CANCER IN ASSOCIATION WITH ASBESTOSIS DIVIDED BY TOTAL DURATION OF EMPLOYMENT IN A SCHEDULED AREA AND BY AGE Total Length of Employment before January , 1933 All Lengths of Employ- ment before Length of 0-9 Years 10-14 Years 15+ Years January , 1933 | Employment 1953 in | | FILED Scheduled or at No. No. of Men No. of No. of No. of No. of with No. of No. No. of with No. of " No. Asbes- No. | | Area | Men Men with of Men Men with Men Men with of Men Men with Asbes- Cancer Men Cancer Asbes- Cancer Men Asbes- Cancer - years Men years Men tosis of Lung tosis of Lung tosis of Lung tosis of Lung 11-23-00-122-111 14735320- 2023 258275 ] oo | || 12843I 11-300-11 1473520- 1-2301- E PEltya Ome -20- 2587 1-30-1 20-24 531473520- 1032-0 ew 1032-0 11 [ OUR Oct 12843I RK 18 --- 12843I | ||||| man 11-300-11 1-230-12-1 45-45-45- MO63-00 Tad 25-29 60- 11-23-00-122-111 MO63-0 0281- 101 1-0- O326410 1-23-0-12-11 300 1-0-1 mo- LL PITY | / ||| SOS! 12:13 ||||| ||| 12 326572 ||| | Owe 1 T Sa ||| 326572 PM - 326572ma O32641010 | | | | RICHLAND 2 tl || cosHu] 0 Plitl 30-34 53- id COKE PTET one PEdt OMNUS 2-0- ||| OWUN Se RB - - | | |||||| 35+ 6065-9 OS] |||||| |||| co] TTI = ee |||| ||||| 12 oo | | | COM ON -79-272o All 3540- |||||| ||||||| 45- -79-272o 0-5tm<A || || || | 287632- - lengths of employment 50- -79-272o 35- -79-272o in 60- | mmn 15028no PLEAS 282786732- anu scheduled 65- -792o -0- | ** <28-0 0-5tm<A 287632- 15028no | 2-0 PLEAS yrs yrs 75- 80-4 o LT] ||| 0-5tm<A - All ages 61 61 13 13 - 26 | 14 14 we 26 26 16 16 7 113 113 113 43 43 -_ ad 1 been employed for 20 to 24 years in the areas in which they might be exposed to asbestos dust were found to have asbestosis and lung cancer Since three men had worked for under 10 years in the pre- 1933 conditions three had worked for 10 to 14 years and three had worked for 15 or more years the expected number of cases in each of the 1933 employment groups would have been the same i.e. 3 ^ 3/9 or 1. In fact the numbers of cases found were 0 1 and 2. The total numbers expected in each 1933 employment group are obtained by adding the numbers calculated for each of the age and total employment groups within it follows : The results are as The differences between the numbers of men observed and the numbers expected in each employ- ment group had the incidence of the conditions remained steady throughout are statistically signi- ficant total asbestosis x= 7-52 = 2 P = 0.025 asbestosis and lung cancer x= 8.74 = 2 P = 0.01 They are highly so if the trend that is Total number of men with asbestosis observed expected Number of men with | observed asbestosis and lung J expected cancer Length of Employment before January 1 1933 Under 10 Years 13 21-9 10-14 Years 14 10.3 15 Years and Over 16 10-8 1 5-5 3 2.4 7 3-1 * The expected numbers of lung cancer are small and the probability that the differences could arise by chance has consequently been somewhat but not seriously underestimated If all men with more than 10 years 1933 employment are grouped together and Yates correction made for small numbers x = 5.82 n = 1 P = 0.02 CASE 2023CP4001759 203CP41759 86 BRITISH JOURNAL OF INDUSTRIAL MEDICINE ELCTRONIAY the biologically important reduction in the propor- tion between observed and expected numbers as the length of 1933 employment is reduced is also taken into consideration It is clear therefore that the incidences both of asbestosis and of lung cancer One hundred and thirteen men who had worked for at least 20 years in places where they were liable to be exposed to asbestos dust were followed up and the mortality among them compared with that which would have been expected on the basis of the associated with asbestosis have become progressively mortality experience of the whole male population FILED less as the number of years during which men were exposed to the 1933 conditions has decreased Thirty deaths occurred in the group whereas 15.4 were expected The excess was entirely due - The extent of the risk of lung cancer over the to excess deaths from lung cancer 11 against whole period among the men studied appears to have been of the order of 10 times that experienced by 0.8 expected and from other respiratory and cardiovascular diseases 22 against 7.6 expected 2023 Oct other men This agrees well with the data reported by Merewether 1949 but it is somewhat greater All the cases of lung cancer were confirmed histologically and all were associated with the presence than that suggested by Gloyne's data 1951 The of asbestosis 18 great reduction in the amount of dust produced in From the data it can be concluded that lung cancer 12:13 asbestos works during the period has been accom- panied by a reduction in the incidence of lung cancer was a specific industrial hazard of certain asbestos workers and that the average risk among men PM among the workmen so that the risk before 1933 is employed for 20 or more years has been of the order likely to have been considerably perhaps 20 of 10 times that experienced by the general popula- times the general risk Whether the specific industrial tion The risk has become progressively less as the risk of lung cancer has yet been completely eliminated duration of employment under the old dusty con- RICHLAND cannot be determined with certainty ; the number of men at risk who have been exposed to the new conditions only and who have been employed for a sufficient length of time is at present too small for ditions has decreased I would like to offer my thanks to the management of the firm concerned for permission to carry out this work - confidence to be placed in their experience It is and to the Medical Officer and members of the staff of COM ON clear however that the risk has for some time been greatly reduced The extent of the reduction is particularly striking when it is recalled that between 1933 and 1953 the incidence of the disease among the works where the men were employed who carried out the greater part of the work on which this report is based REFERENCES men in the country at large has increased sixfold Asbestos Industry Regulations 1931 Statutory Rules and Orders PLEAS 1931 No. 1140. H.M.S.O. London Summary Boemke F. 1953 Med Mschr 7 77 Cartier P. 1952 Arch industr Hyg 5 262 contribution to PLEAS The cause of death as determined at necropsy is discussion Council of the International Organizations of Medical Sciences - reported for 105 persons who had been employed at 1953 Acta Un int Cancr 9 443 one asbestos works Lung cancer was found in 18 Doll R. 1953 Brit med J. 2 521 Gloyne S. R. 1951 Lancet 1 810 instances 15 times in association with asbestosis Hueper W. C. 1952 Proceedings of the Seventh Saranac Symposium To be published All the subjects in whom both conditions were found had started employment in the industry before 1923 Lynch K. M. and Smith W. A. 1935 Amer J. Cancer 24 56 Merewether E. R. A. 1949 Annual Report of the Chief Inspector of Factories for the Year 1947. H.M.S.O. London and had worked in the industry at least nine years Nordmann M. and Sorge A. 1941 Z. Krebsforsch 51 168 Smith W. E. 1952 Arch industr Hyg 5 . 203CP41759 before the regulations for the control of dust had become effective Stocks P. 1952 Brit J. Cancer 6 99Amer Vorwald A. J. and Karr J. W. 1938 Amer J. Path 14 49 Warren S. 1948 Occup Med 5 249