Document wgaNjZLYaZ5kow8Z2DX9JaKVQ

FILE NAME State of the Art Literature SAL DATE 1955 DOC SAL061 DOCUMENT DESCRIPTION Journal Article - Mortality from Lung Cancer in Asbestos Workers i an re ele .. . : en Deteticahecans 6. Fa Brit J. industr Med 1955 12 81 *; . _ a . a . . - ae a "4 : a. . . Loe 4 . i ve iota ntdeipets isu at ane Te pT ree eee 122 a rr . Ror ~ % ; MORTALITY FROM LUNG CANCER IN ASBESTOS WORKERS BY RICHARD DOLL From the Statistical Research RECEIVED FOR Unit Medical Research Council PUBLICATION august 10 1954. London Sixty cases of lung cancer have been recorded in persons with asbestosis Boemke 1953 Hueper 1952 since Lynch and Smith 1935 reported the first case In view of the infrequency of asbestosis this large number of cases suggests does not prove lung cancer is an occupational hazard of asbestos workers The strongest evidence that it may be a hazard has been produced by Merewether 7 , om Merewether Gloyne 1949 found that lung was reported at necropsy in 13.2 of cases Estosis 31 out of 235 but in only % of ses of silicosis 91 out of 6,884 and Gloyne 1951 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 Neither author gave full details of the sex composition of the groups examined but since women form a higher proportion of asbestos workers than of persons employed in occupations liable to give rise to silicosis miners stonemasons pottery workers foundrymen metal grinders and since lung Calmer is less common among women the differences in the proportions of cancer cases cannot be accounted for by differences in sex distribution In fact the proportions which are more properly comparable 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 considers that one of the " carcinomas was in fact an example of squanious metaplasia and that the other an adenocarcinoma may have developed spontaneously from the common mouse adenoma negative negative result has been reported by Vorwald and eo / 938 The majority of workers cited by KX 81 = Hueper 1952 consider that a causal relationship between asbestosis and lung cancer is either proved or is highly probable and the reality of the relation- ship was agreed at the recent International Sym- posium on the Endemiology of Lung Cancer Council of the International Organizations of Medical Sciences 1953 A minority however remains sceptical Cartier 1952 Warren 1948 and according to I lueper 1952 Lanza and Vorwald so that it was thought desirable to undertake a fresh investigation , Necropsy Data Since 1935 records have been collected of all the coroners necropsies on persons known to have been employed at a large asbestos works Pathological diagnoses in 105 consecutive cases are summarized in Table 1. Details of the cases in TABLE 1 CAUSIS OF DEATH DIAGNOSED AT NECROPSY AMONG PERSONS EMPLOYED AT AN ASBESTOS WORKS 1933 52 Cause of Death AsPbreessteonstis | AsAbbessteonstis Heart failure 34 { Pulnionary tuberculosis oe 12 cancer .. respirator respirator 15 | aw > 3 Other diseases of the respirator System oe o oes 10 4 Other diseases .. - 4 an 3 All Cases 45 21 6 14 ui All causes 75 Se 30 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 the second half of the period there were seven such cases and a further thee in which lung cancer was found without asbestosis The number of asbestos workers employed at the works increased steadily from 1914 ce wee 2 ears nt me ' coroner Necropsies on asbestos workers are ordered by the coroner when in his opinion there may be a question of asbestosis being a contras butory cause of death . ' 122 122122 PLAINTIFF'S EXHIBIT = . P 7 _ - - . 7 s * 3 9 : . ; 6 = :, te Loreal Oe . 5 Res Ae ney t 5 a ae ogy K, . Pe bh ae . e fo yee . o * She ge * | 4 9S oe eT Pra eee anaeres te Os Hod Kets Ot Nidbee Cows CL EST ot, Aety twys irene ede Jat. 0d att oh Aesth hah A Oe A hey i} ] 44 4 Lote tos ae RP to eed hay e 8 chee lot re i ee ve Foaes te a ~y Sc (tN tt SL age ee. ee . ee . bos, eg va ivemes Si wot Ph. tae ae ote -., * lg - sew . . : angel a Se we : my ASICS pepha Bn XL Gj edal p . . , ar ee tee "1 44 J . di nl + 3a ' a : . 74 j 4 Jf j , : . | re, | 4. } and ! . % . ] ; 2 . 4 At . . F- . ies 4 8' a wee oe ov i ar ; 2:. - -i F 4-4 or oer or . bs | 4 wd 4 ^' oo tf f o. . ae 3 a .o 4 3 -40@ 1 -- yyae a aes oP ars awa a Poe ae ee Ry a4 84 | 3] rs, SERS ayes ps3/ oor a\ Fy 82 MEDICINE BRITISII Journal of INDUSTRIAL MEDICINE TABLE 2 OCCUPATIONAL HISTORY AND NECROPSsy data of ASBESTOS WORKERS WITII PRIMARY LUNG CANCER Sen Year Death and Ast OccupationOccupationOc upation : : Perofiod Exposure 1935 | M. 62 Weaver 1919-31 1935 | M. Weaver 1935 | M. | Fiberizer 1938 | M. | Weaver 1939 | M. | Disintegrater 1940 | M. | Disintegrater 1941 1942 | M. |] M. 19 | Weaver Bag carrier 1909-32 1913 36 1920-37 1910-14 1911-15 i] 11991293--2319 1913-19 1913-41 1948 | M. | Weaver 1948 | M. | Weaver 1948 | M. | Spinner 1912-14 1922-33 1922 48 1943 | M. | Maintenance man 1919-48 1950 | F. I Spinner 1915 42 1931 | M. | Fiberiser 1921 | M. | Weaver 1917-43 1929-30 Years of Years Years Exposure of Exposure | | i before Jan. , 1933 First First Exposure to Death 13 : 16 23 23 26 23 19 23 19 14 28 24 17 29 22 is 1 20 34 i 28 28 19 32 16 10 10 | 26 10 a 3 & 36 [ 26 26 29 13 19 27 17 33 26 13 1 71 8 " 32 Years from Last Exposure Exposure Death Pathological Report . Asbestosis . Primary Lung Cancer Asbestosis Flistological Type 3 3 than 1 than , Present Carcinoma i ~ Epithelial carcinoma sn Endotheloif polemuraa | ow |, | Carcinoma * Carcinoma Less >, : S| gn - >on Carcinoma " Carcinoma | celled celled carcinoma carcinunua than =| Anaplastic carcinoma - *Carcinoma than =. " * Carcinoma Less than nfi | celled carcinoma 8 : * ' Carcinoma s re Adenocarcinoma mo. ' Carcinoma 1944 | M. | Weaser 1931 | M. | Fiberizer 1932 | M. | Weaver 1942-44 2 1939-48 1945-52 {| ok 0 | o te . 2 Less = Absent | celled carcinou . 12 3 es Anaplastic carcinonis 11 than Carcinoma . * Also pulmonary tuberculosis and a great increase in the number of lung cancer ldaetaitohns larger popu- was also recorded among the whole of England and Wales over the sanie period It might therefore have been anticipated that a number of cases in which the two conditions were associated would have been found in the last 10 years National regulations for the control of asbestos dust were however introduced in 1931 Asbestos Industry Regulations 1931 and the precautions taken to prevent dust disseminatiionn the works had become effective by the end of the following year All the subjects in whom the two diseases were found together had been employed for at least nine years under the old conditions and 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 years 1923-53 It is therefore possible that the reason more cases were not found in the second half of the period is that reduced exposure to dust has already begun to lessen the incidence and severity asbestosis of asbestosis Method of Estimation of Risk Although the necropsy data shown in Tables I and 2 suggest ) that some groups of asbestos workers have suffered an increased risk of lung cancer and 2 that the risk may now have decreased it is not possible to be certain of either of these propositions without a more detailed knowledge of the whole mortality experience of the workers The first proposition has therefore been tested by comparing the mortality experienced by that section of the male employees of the works referred to a11 bove who had worked for at least 20 years in scheduled areas *** with the mortality recorded for all men in England and Wales and the second 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 employed for at least 20 years since the labour involved in searching out the individual records of A scheduled greas were carried on which were Regulations of 1931 as being it meant scheduled dusty those areas where procent under the AsbesAtsobsestos iinndusty dusty ae a. . ete * ttmnthhe Sve sp Dasa , se wt Auge Oey, ot gett ett Ryoat ee ars ee Ne om tm: on sank caliente, mel petite toandond taint mens ie fan i) sertswe atin ea? LUNG CANCER IN ASBESTOS WORKERS 83 diame ora bent employed for shorter periods would be dis ortionately gitat and so far as was known Table 2 would be comparatively unrewarding e date of birth date of completing 20 years in " the scheduled areas " and where applic- date of casingemploynient and date and cause bath were obtained for each man from the is of the firm's Personnel Officer Full details in most instances already available the men had ceased employment as well as for the greater yer who continued to be employed since some inse who had left were registered as having tosis and the attention of the firm had been in to the death of others in view of the bility of the cause of death being industrial in 1. All the remaining men were successfully and the relevant details obtained This was fanficult since by limiting the study to men who been employed in one place for 20 years few found to have changed their job or to have out of the region om the data the numbers of men alive in each year age group were counted separately for each from 1922 the first in which a man was a~ laving had 20 years service to 1953. A completed the 20 years before the begin- or year and who was alive at the end of it was ted for that year as one unit a man who pleted the period before the beginning ofa year cho died during it and a man who completed the d during a year and who survived to the end of ere each counted for that year as half unit the man who died the same year as he completed his zar period was counted as a quarter of a unit se causes of death were recorded as they were or the death certificate or when available us 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 therefore estimated to be 15 + 15 + 17 19 + 19 ^ 1,000 = 0.238 The total number of deaths expected from each category of diseases was obtained by adding the numbers thuis calculated for cach age group for each of the five periods The great majority of the men lived and when they died died in the town in which the works was situated so that it would have been preferable to have based the calculation of the expected deaths on the death rates observed in that town rather than on the rates for all England and Wales These however were not known in suflicient detail Little error in the expected number of deaths from lung cancer is likely to have been introduced on this account since according to Stocks 1952 the adjusted death rate for lung cancer among men in the town concerned was 96 of the rate for England and Wales Stucks'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 investigation The expected number of deaths from all causes is however likely to be somewhat underestimated since the adjusted death rate from all causes for the town is about 25 higher than the England and Wales rate ie the excess was 22 in 1950 28 in 1951 and 22 in 1952 Results The number of men studied was 113 ; the numbers of years lived in each of the five periods in each age group are shown in Table 3. The total number were finally determined by necropsy The causes Table 3 classified in five categories see Table 4 and the hers in each category were then compared with NUMBER OF YEAHS LIVED BY MEN WITH 20 OR MORE YEARS OF WORK IN A SCHEDULED AREA : which might have been expected to accur by iplying the numbers of men alive in each five- age group by the corresponding mortality rates men in England and Wales over the same period use of the small numbers however the popula i were not considered separately for each year were added together to form five groups living Ace years 1 1922-33 1934 30- 354043- 0 4.5 | 9.5 95.) o3 2 16 195 30- os] 23.3 ... ) 60 is ) e periods 1922-33 1934 318939 431944 48 05 10- { 13.5 6 2 1919-53 and the mortality rates used for each 75-79 0 a p were those for the years 1931 1936 1941 and 1951. The rates for 1931 were used for the ages 58 | 88 Period _ |318939 |413944 1.3 tt 17.5 33.5 41 30 39 | 303.25 78.3 35 32 23.9 p 10 7 1 14 | 183-75 321 |418949 AR Periods 33 r t 35 44 35 162 84 | 96.1 | 05.3 { 36 241 233 185.5 04.73 21.3 49 Ms 17.3 oS 3 | 1 391-3 1042-25 id 1922-33 rather than those for the years : disproportionately few men were under rvation during the early part of the period As xample of the method the mortality rate for all Fa other than lung cancer among men in of deaths from all causes and the number of deaths observed in each of the five discuse categories together with the expected number of deaths are shown in Table 4. From Table 4 it appears that the men who had been exposed to asbestos dust sulfered er nati we Pesan easewer : eite, 2 a . oo te, WOT ete ray Wt y= POND oharefi ote Att eee at Rel tae te 0 DACRE. ORT ery PET . ie renyS Teya]of no Bh be PEDALSie oe o aeeth r ehe tee a ws Anes al 4. we Lt e ee eM ao C ~re cy voginng IK ade os Wee come pou tm . a sats aea Abe AP Bove 2. ome oe tare sae ee Fame. ea kk Kae Ly ee var, Vie wtf. Slye g _ tew nd nore ae =! - odd 84 ad th BRITISH JOUrnal of industrial MEDICINE od ee Gon. ... mage we eo ... ... ... _ ~ do oo e lsenncth Loe ardin 2 ' temietanl aa ste = 28 Peres verte Dov . Hae . conn ae we Tene Say odd : wen) in by ee hmasetalh oa! ea.Cerda w, . - ' ntiteScie > 2 To S Brecat fettle. eae wey 4a) VP WY nr) enersy yrbatat ib . nae an ~~ R feuy . Sed . Oe See Table 4 CAUSES OF DEATIE AMONG AMONG MALE ASHISTOS WORKERS COMPARED WITH MORTALITY LXPERIENCE LXPERIENCE OF ALL MLN IN ENGLAND AND WALFS Cause of Death No. of Deaibs Test of Jame ee - 1 Significance Expected od Billerence -- -- | No. England Observed and between Observed and Wiles Expected Rates | Value of P Lung cancer . with mention of asbestosit a) i) without mentiun uf asbeumis - os } 0000001 0000001 Other respiratury diseases includ ing Milmonary tuberculosis and cardiovascular : diseases with nation of asbestosis ., without mention of asbestinis Neoplasms other than lung cancer other diseases .. 4 ^' 4 4 76 76 } 0.001 0.001 } 23 501 aa All causes .. - t 19 1954 } 0000001 0000001 * Including one case with pulmonary tuberculosis fincluding two cases benign stricture of oemiphagus and septicaemia in which asbestous was present but was not thought to bave been a contributory cause of death an increased mortality from lung cancer other respiratory diseases and cardiovascular diseases in association with asbestosis but that their mortality from other diseases was close to that expected Four explanations of the findings are possible: ) 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 underestimation of the expected number of death; 2 that lung cancer was incorrectly and excessively diagnosed among the asbestos workers 3 that hing cancer was insufficiently diagnosed among the general population of England and Wales or 4 that the asbestos workers studied suffered an excess mortality from lung cancer It certainly cannot be claimed that the records of the Personnel Office were necessarily complete hut they were believed to be compl^teand no deficiency 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 is unlikely to have happened unless the population had been estimated approximately correctly and the deaths from all causes fully reported All the 11 deaths attributed to lung cancer were confirmed by necropsy and histological examination so that the excess number cannot be attributed to incorrect diagnosis among the group of asbestos workers Some of the excess may well be due to an underestimation of the expected deaths since part of the increase in mortality attributed to lung cancer over the past 30 years is certainly due to improve ments in diagnosis and in therapy Dull 1953 Even however if it were postulated that the whole of the recorded increase between 1931 and 1951 was spurious and that the real mortality from the disease throughout was that ascribed to it in 1951 the expected number of deaths is increased to only !! and the observed excess is still grossly significant For the actual number of lung cancer cases to be so little in excess of the expected as to be reasonable attributable to chance it would be necessary for the expected cases to be 6-2 that is 5-6 times the number estimated on 1951 rates In other words it would be necessary to postulate that in 1951 and throughest the previous 20 years there was 5.6 times as much cancer of the lung as was recognized in 1931 which would mean that the condition would have to have been present and capable of detection in over 20 of all men at death Moreover even if this were so it would still not account for the fact that all the cases of lung cancer were found in association with asbestosis * It is therefore concluded that the fourth explan ation is the most reasonable one and that asbestos workers who had worked for 20 or more years in the scheduled areas suffered a notably higher risk 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 before the end of 1932 but also to allow for the men's ages and for the total durations of their employment in the scheduled arcas " since the nien eniployed in the earlier periods can also have been employed longer and lived to be older On the other hand there is no need to consider the changing incidence of lung cancer in the total population of England and Wales since the industrial risk has been shown to be small in comparison with the industrial one The data required for comparing the risks aniong mea employed for under 10 years for 10 to 14 years and for 15 years and over in the 1933 conditions are shown in Table 3. The ages shown are the ages at death of the men who have died and the ages in me 1953 for the men who are still alive The expected numbers men in each pre 1933 cmployineat groep found to have asbestosis or asbestosis and lung cancer are estimated by multiplying the numbers in each age total employment and 1933 employe ment subgroup by the proportions of men with asbestosis or with asbestosis and lung cancer the same age and total employment group for all lengths of 1933 employment combined For examp's three out of the nine men aged 50 to 54 years who lud ese aw et . tt et ye. 2 me^' oe tee eE T T TT slMi ad tobe and oe eee OO 71 ony meeer eel ad $ SO ay. cram sos be Toy trary tee None eel we ET! Se en See eT . ree . ? Sew . H . os . ry cow tay Jad et ee tr. - ok . oe as Te ow) . et ya wee ews: eg ny re aneee ort, e ope tor fae k ek s Be re LUNG CANCER IN ASBESTOS WORKERS 85 Table 5 IMBLIES OF MEN EMPLOYED FOR DIFFERENT PERIODS PERIODS BEFORE BEFORE 1911 AND NUMBERS KNOWN TO HAVE ASBESTOSIS T^ LUNG CANCER IN ASSOCIATION WITH ASHESTOSIS DIVIDEU BY TOTAL DURATION OF EMPLOYMENT IN A SCHEDULED AREA AND BY AGB Tamal eaystt a Nouvel Nouvel Nouvel Nouvel Nouvel Ares prats (9eats} eee I ength ee emer -o- 0-9 Yeare of 1.niploynient before we el 10-14 Yeara January , tee 1933 No. of All Lengths of Employ ment befor No. of 1923 No No No of 1 No. of | No of No. of Asbew Cancer 10118 of Lung | New of | No. of 1 No. of No. of No. of MenMen | Asbes- Busso Cancer of Lung { No. Men No.No. of | No. of of No. of | Asbess tosis | | Cancer of Lung NNoo.. Men No.No. of | No. of of of No. of Aabess tosia Cancer of Lung 3S~ t 11-004-11 | ~ONUued rere Therse | | Lbecomt UOrKe @- 43. 10- | 332 od CODEN 6 0 33-9 Ouw=O0 ovary 1-04-1 wean Geer 11-004-11 mcneswase awe | INE trelds 0-24 -- 3063-0 INNE L 306-0 10-1-0 1-0-1 10-10 111-000-1 10- 0 1-10-1 mon nf 1-11-0-11 Biandew anual] e cmeGm 111-111 LEBEETLE LEBEETLE LEBEETLE LEBEETLE LEBETLE 10-35 LEBT LEBTLE LEBETLE LEBT LEBETLE LEBETLE LEBTLE LEBETLE 1-10-1 LEBLEEBETLTELE LEBTLE COl ttt 19 35- 40~ 4- | wengths of 19 Inglisment Inglisment In 5055O- scheduled 65- OwnrNe arca 0~ -ocasulOm 20 L+ 73- 30.4 | All ages 61 61 13 13 aa coe! 1 Terr PELdbati Pa-Tore -- 26 \ rs |||||| Mew!) |||| OSOl] ||||||| menu ~~ 26 26 16 16 ed 60] 111 --11 --11 Tee ||| SIMON -ON --11 hoPneerr mes a | poye re | 7 113 113 113 43 43 | = sen employed for 20 to 24 years in the areas in hich they might be exposed to asbestos dust were und to have asbestosis and lung cancer Since free men had worked for under 10 years in the pre- 133 conditions three had worked for 10 to 14 years ad three had worked for 15 or more years the spected number of cases in each of the 1933 mployment groups would have been the same i.e. 3,9 3,9 or 1. In fact the numbers of cases found cre 0 1 and 2. The total numbers expected in each 1933 employment group are obtained by adding se numbers calculated for each of the age and total mployment groups within it llous : The results are as The differences between the numbers of men bserved and the numbers expected in each employ- ient group had the incidence of the conditions mained steady throughout are statistically signi- ficant total asbestosis = 52 n = 2. P = 025 asbestosis and lung cancer x"= 8.74 n = 2 P = 01 They are highly so if the trend that is Length of Employment before January , 1933 Under : 10 Years asbestosis } Total with asbestosis ubserved eapecied Numofb mee n wr ith observed | asbestosis } expected expected cancer | 21.8 1 $$ 10-14 Yean 14 10-3 J 24 15 Years || and Over 16 10.8 7 v2 T he experied numbers of lung cancer are sniait and the probability that the differences could arise by chance has consequently been somewhat somewhsomaewhtat but not seriously underestimated If all men with more than 10 years pre 1933 employment are grouped together and Yates correction made for small numbers x" 3.82 - 1. 002 otve . gus te 8 tae CMeey an ye Oe og te te wf bo a My 7 el . As eit oote tat a e Sard erdcl heson81 et Sar ne on er en af PTI 7 2. OU Py ad ae aafe Da Sa t PRPrt ; aot em . Maney # wpbe s . MyArdeg i Mite: vag emceon AND Scents OOEOfi s came a oie 22434 UA? ets ed i \ . % ifot ary,oe | ad404 -, Sar 4Osan - Ton 7 wan hanes Re ere tives SetJub Bnei.- te atgat a ll 7 e be net, = cae . nen . ot we . . tne yO . 89 Me ment . 6 fa,me. teet aly a oc kd om. ge + serne a ol oat ew td tiyodne, oity SOREL~~ oY dae m 4tepmnietd-e4 4 4 PF N . 4 ~~: }* Baba bef 323 oe a Pays was AS net . Spas } 7. 7 ae On toe tag i ae oe . OY a sey a) s a oe ee . . ha rh oo aan neers A baw HE . ae Lyecuee ele, . yee a ewe Le he te gee ee ane Sg meet Fee al om ade uA thhaatse9aknne a nt meee ay anSeenl Cole me Y NtsBoPotORES EAS FE CRISTAE date ad ALOE 86 britisii journal of induUSTRIAL Medicine the biologically insportant reduction in the proportion 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 associated with asbestosis have become progressively less as the nuniber of years during which men were exposed to the 1933 conditions has decreased. thirteen One hundred and men who had worked for at least 20 years in places where they were lighte to be exposed to asbestos dust were followed up an the mortality among them compared with that which would have been expected on the basis of the mortality experience of the whole male population = Thirty deaths occurred in the group wherea 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 again whole period among the men studied appears have 0 expected and from other respiratory an been of the order of 10 times that experienced by cardiovascular diseases 22 against 7-6 expected other men This agrees well with the data reported All the cases of lung cancer were confirmed histe by Merewether 1949 but it is somewhat greater logically and all were associated with the presence than that suggested by Gloyne's data 1951 The of asbestosis great reduction in the amount of dust produced in asbestos works during the period has been accompanied by a reduction in the incidence of lung cancer From the data it can be concluded that lung cancer was a specific industrial hazard of certain asbesto workers and that the average risk among men among the workmen so that the risk before 1933 is likely to have been considerably perhaps 20 ,, times the general risk Whether the specific industrial risk of lung cancer has yet been completely eliminated cannot be determined with certainty ; the number of employed for 20 or more years has been of the order of 10 times that experienced by the general populztion The risk has become progressively less as the duration of employment under the old dusty con- ditions has decreased men at risk who have been exposed to the new conditions only and who have been employed for a I would like to offer my thanks to the management v sufficient length of time is at present too small for the firm concerned for permission to carry o^tthis work confidence to be placed in their experience It is 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 and to the Medical Officer and employedwho staff carried out the greater partof the work on which this report based disease 1933 and 1953 the incidence of the among men in the country at large has increased sixfold REFERENCES Asbestos Industry Regulations 1931 Statutory Rules and Oriders Summary Summary determined is The cause of death as determined at necropsy is reported for 105 persons who had been employed at one asbestos works Lung cancer was found in 18 instances 15 times in association with asbestosis All the subjects in whom both conditions were found employment had started in the industry before 1923 in industry nine and had worked in the industry at least nine years before the regulations for the control of dust had effective become effective Boembe F. ) Aleid Mschr , . P. Cartier 1952 Arch indiestr Hyg 5 262 contibution to Council of the International Organizations of Medical Sciences 1951 Un Acta int Concr 9 44 Gl^R,. y19n53e Meit FunJ. c8e1s0 Huther Huther W. To Procpublisehed Perodcieendigngss of the Seventh Saranne Symm Lynch K. and Smith W. A. 1935 Anur J. Cancer .16 Merewether R. A. 1949 Annual Report of the Chief Inspect * of Facturies for the Year 1947. H.M.5.0 London Nordmann M. and Sorge 1911 Z. Krebsforsen , 51 51 168 Krebsforsen Smith 1952 Arch industr Hve Krebsforsen P. Vorwald 1952 Karr J. Cancer 1938 99 Vorwald A. J. and Warren 14 Karr J. W. , Amer Amer. JJ . .Pask Pask 14 49 Occup Med 249 nn . A oe aan . ads om wea pes . ~ 232 At e CR : TR pee Sees . ae ial . : is iarn an : ' fi wee. naoe e 5 een* tr . yee etm Pee age * merry gvyper mre on we ; PR. TONS Pr enee ar te Pe . ete . liu Te tee aren) et es ee . Aone a es A Mape re ue ee