Document Lpvr0YgG9dM0V8zooyBnbwM03

FILE NAME: Owens Illinois Library (OWL) DATE: 1955 DOC#: OWL049 DOCUMENT DESCRIPTION: Journal Article - Mortality from Lung Cancer Asbestos Workers Brit. J, indiatr. Afed., 1955, 12, 81. C . - I 9 & MORTALITY FROM LUNG CANCER IN ASBESTOS WORKERS BY RICHARD DOLL From the SiatUlical Research Unit, Mnlitol Research Council, London (ECLIVtO OR PUIIUCATION AUGUST 10, 1934.) Sixty-one cases of lung cancer have been recorded Ilueper, 1952) consider that a causal relationship in persons with asbestosis (Buvmke, 1953 : 1lueper, between asbestosis and lung cancer is either proved 1952) since Lynch and Smith (1935) reported the ur is highly probable and the reality of the relation first case. In view of the infrequency of asbestosis, ship was agreed at the recent International Sym this large number of eases suggests--but docs not posium on the Kndcmiology of Lung Cancer prove--tltat lung cancer is an occupational hazard (Council of the International Organizations of of asbestos workers. The strongest evidence that it Medical Sciences, 1953). A minority, however, may be a hazard Itas been produced by Mcrewether remains sceptical (Cartier, 1952; Warren, 1948), r 'NGloyne. Mcrewether (1949) found that lung and,according to i Iucpcr(l952), Lanza and Vorwald, f was reported at necropsy in 13-2% of eases so that it was thought desirable to undertake a ' xstosis (31 out of 235) but in only 1*3% of fresh investigation. u .sn of silicosis (91 out of 6,884) and Gloync (1951), on personal examination, found lung cancer in Necropsy Data 14*1% of necropsies on subjects with asbestosis (17 Since 1935, records have been collected o f all the out of 121) against 6*9% in silicotics (55 out of 796). 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 eases are form a higher proportion of asbestos workers than summarized in Table 1. Details of the eases in of persons employed in occupations liable to give rise to silicosis (coal-miners, stonemasons, puttcry workers, foundrymen, metal grinders) and since lung T able 1 CAUSI S OF UEATII DIAGNOSED AT NECROPSY AMONG PERSONS EMPLOYED AT AN ASIIESTOS WORKS (I9JS-32) catiwr is less common among women, the differences in the proportions of cancer eases cannot be Cum or D,ih Atbettotn Aibuiotii Preaent Absent CAulel accounted for by differences in sex distribution. In llcdfi failure** . M fact the proportions which are more properly com Pulmonary tuberculoma l.unt cancer .. 12 IS parable with the findings in silicotic subjects ate the Other ilttcattf of the respiratory proportions of lung cancer found among men with stem OibrdiwiKi .. .. .. 140 a1s9b-6e%stoisnisG, lo1y7n*c2'%s. in Mcrcwvthcr's series and Allauio 1 n It 45 1 2t1t 4 i 14 t JO IOS Animal experiments are inconclusive. A positive result was reported by Nordmann aiul Sorgo (1941) who found that of 10 mice which had been exposed to asbestos dust and survived for 240 days, two developed iung carcinoma. Smith (1952), however, 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. which lung cancer was found are shown in Table 2. During (he first half of the period eight deaths occurred in which lung cancer was found in asso ciation with asbestosis, while <>t the second half of the period there were seven such cases and a further tlnce in which lung cancer was found without asbestosis. The number of asbestos workers employed at the works increased steadily from 1914. A necgative ressult has been reported by Vorwald and ^V>38). The majority of workers (cited by N > v ro |itic i u n tlM tio i < w l> m rg or*Jr4 b> l l l( CPW IKf ii h it o p i n i o n , ih e ie m t) be a qwettm n o f a t b c t io u i b o n g a coutft* h u itiry taut# o f death 81 C plain rifrs i EXHIBIT  -. :, ' . | l>- * i. , , \H* . > ! . ' **' * . >t J .J*v.<' , :r,vT**",t - *t ' t - v -*^-( \- .............. .",*% . , 1 . ` S j r: \ * l ' . h,. .TT* > v.^ast^ ). 82 BRITISH JOURNAL OF INDUSTRIAL MEDICINE Tabu 2 OCCUPATIONAL HISTORY AND NECROPSY DATA OF ASOCSTOS WORKERS WTTII PRIMARY LUNG CANCER I I or and Death A* IV1S 1*11 IBM l*M 1*1 1*40 1*41 1942 1*44 194* 1*41 194 I9S0 I9SI 19! 1 M.4X M.S4 M.4S M.4T M.49 M.12 M. 12 M. 19 M.19 M.11 M.44 M. 41 F. It M.T4 M. 60 1944 M. 14 I9SI M.4J 1912 M.1I Occupation if Ciptiwn ~<a Eepowre YtanoT before Jan. 1. 19 You 9*nt Eipntuft to Death W nw 1*19-12 Weaver Fibvruef W tm t Ditintcrater D bianirw r Weaver Ba| carrier Weaver Weaver 1909-22 1912.14 /1*10 12 \ 1920.17 /19HM4 11*1909 ru u -if ( 1919.21 l 192u n /1911.19 \ 191404 1911-41 / 1912-14 \ 1914-44 1922-11 Spinner 1922 4 Maintenance man 1919-4 Spinner 1911--42 Fibcrircr Weaver 1917-41 / 1919-25 \ 1929-10 1) 1) 2) 2) 2) 1 19 14 24 IT 22 IS 20 14 12 < t) to 24 to 29 I) 27 IT 24 27 i 14 24 2) 2 29 29 2 29 14 24 24 29 21 14 22 Weaver Kibcriecr Weaver 1942-44 2 | * 1919-4 ! # / 1941(1 12) \ 1941-12 . :. o ! i Alto pulmonary tubercukiiia. Year* from Lew Evpoaure to Doth Pathological Report Alhcwodt IfiMotofkal T*ot of Primary Lung C m m 1 j Prevent ) 1! " Leaathanl J m 1 i- Lew then 1 i 1 * lets than 1 1 m * Carcinoma * Epithelial n ie w m t Endothelioma of ptenej * Carcinoma * ` Carcinoma1* ` Carcinoma* 9 m 1 m Leu than 1 ao 1) m Latathan 1 m Leu than 1 1 m 1 im 1 Ool-Ucd eervieama Ovt-ccUed caeriouma Arvaptauie tatriaan. ` Carcinoma* ` Caiciooma* O lK tllld Cltciliooi "Carcinoma* Adenocarcinoma "Carcinoma" Leu than 1 S Leu than 1 Abtcot m m Oa4*<elkU catc*oo>u Anaploatio uicnovu ` Carcinoma* i .w 4V. ir; a r.vc X*jlI l& i-a M V ' n is tK +i \ h.I .V and a great increase in the number o f lung cancer deaths was abo recorded among the whole popu lation of England and Wales over the same period. It might, therefore, have been anticipated that a larger 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 dbscminattoirrnthe works had become effective by the end of the ' following year. Alt 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 of asbestosis. Method of Estimation of Risk Although the necropsy data shown in Tables I and 2 suggest (I) 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 above, 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 prc-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 n> "vchcvJulcd ertat" it mom thove area where proee-e r i frini on hiclv acre tchrduMJ under live Aabettoa imiu^o Ketulatiom of IUI n bem* du). ) *? * -**-,V-T5 7 rrp w > rsrr ' -.".v ' ; -r '/ * *-elv:S ^.v/V w ^> v-v : -rX ''' LUNG CANCER IN ASIIESTUS WORKERS 83 employed fur shorter periods would he di>- England and Wales aged 55 In 59 in 1951 was 2-778 -'itionalcly gical nod, so Ter as was known per 1,000. The uumljcrs of years lived in this age Table 2, would be compaialivcty unicwmding. Croup in the live years 1040-33 were respectively c date of birth, dale of completing 20 years' 15 years, 15 years, 17J ycais, 10 years, and 19 years. . in the " scheduled areas ", and, where applic- The number of deaths expected in the period was, date of ceasing employment and date and muse therefore, estimated to be (15 -f 15 4- I7J + 19 + Mth were obtained, for each man, front the 10) :< 2-778/1,000 -0 -2 3 8 . The total number of ds of the film's Personnel Officer, i-'ull details deaths expected from each category of diseases was . in most instances, already available fur the men obtained by adding the numbers thus calculated for ludceased employment as well as for the greater each age group for each of the five periods. tier who continued to be employed, since some The great majority of the men lived and, when they ><<sc who had left were- registered as having died, died in the town in which the works was tesis and the attention of the firm hail been situated, so that it would have been preferable to n to tho death of others, in view of the have based the calculation of the expected deaths on bility of the cause of death being industrial in the death rates observed in that town rather than on -t. All the remaining men were successfully lire rates for all England and Wales. These, however, .1 and the relevant details obtained. This was were not known in sullicicnt detail. Little error in Mtlcull since, by limiting the study to men who the expected number of deaths front lung cancer is been employed in one place for 20 years, few likely to have been introduced on this account since, found to have changed their job or to have according to Slocks (1952), the age-adjusted death d out of the region. rate for lung cancer among men in the town con* on the data (he numbers of men alive in each ccrncd was 96% of tire rate for England and Wales. ear age group were counted separately for each Stocks's figure was calculated only for the period c ""'Vfrom 1922 (the first in which a man was 1946-49, hut the proportion is unlikely to have laving had 20 years' service) to I9S3. A varied greatly over the longer period of the investi A completed the 20 years before the begin* gation. The expected number of deaths from all o ra year and who was alive at the end of it was causes is, however, likely to be somewhat under ted. for that year, as one u n it; a man who estimated since the age-adjusted death rate from all pteted the period before the beginning of a year causes for the town is about 25% higher than the tho died during it, and a man who completed the England and Wales rate (/.<'. the excess was 22% in <0 during a year and who survived to the end of 1950. 28% in 1951, and 22% in 1932). ;rc each counted, for that year, as half a u nit; the sun who died the same year as he completed his Results rar period was counted as a quarter of a unit. The number of men studied svas 113 ; the numbers k causes of death were recorded as they were of man-years lived in each of the five periods in each i or the death certificate or, when available, as age group are shown in Table 3. The total number were finally determined by necropsy. The causes T able 3 classified in five categories (see Table 4). and the NUMIIFR o r MAN-YI-AMS LIVCI) HY MEN WITH 20 OR tiers in each category were then compared with MOKE YEARS OF WORK IN A - SCIILOULCI) AREA** ,,which might have been expected to occur by Ace rtfra* AH plying the numbers of men alive in each five* <>**') 1922-55 1954-54 1959-45 1944-44 1949-55 rtfio d i age group by the conesponding moitality rales nen in England and Wales over the same period, JOJ5- 0 05 15 0 0 4 J 2 It 15-S 9 2 44 use of the small numbers, however, (lie pnpula- 40 45- 95 14 5 )5 41 55 9 5. 19 5 50 its 14 142 241-9 t were not considered separately for each year, 90- 45 15 5 59 5 IS 94-9 251 were added together to form five groups living M . 60. 11 15 4 50 52 455 llt-S 5 523 u s M 44 IS e periods 1922-33, 1934-38, I939-4J, I'.*44--18, 65- 70- 1 155 5 10 21S 4 0 2 9 5 a 11-5 1019-53, and the mortality rates used for each 15-79 0 0 1 13 O-J 5 \ p were those for the years 1931, 1936. 1941, All ice* .and 1931. The rates for 1931 were used for the 41 195-5} 521 591-5 1 1042 25 >J 1922-33, rather than those fur the mid-years, of deaths from all causes and the number of deaths : disproportionately few men were under observed in each of the live discuse categories, isalion during the early part of the period. As together with the expected number of deaths, are '.ample of the method, the mortality rate for all sliown in Table 4. f rom Table 4 it appears that the J\oilicr than lung cancer among men in men who had been exposed-to asbestos dust sulfercd m i .m - . c_ i . i. . r*V .., . i v ! +, r , <*. i ; *w> > c\ -r.,r. # 84 BRITISH JOURNAL OF INDUSTRIAL MEDICINE T aiiik 4 the increase in mortality attributed to lung cancer Causi x ok ih a iii amono maif. asm sin s wouki.ks COMFAKI.D Willi MOMIALIIY L.M'LKII NCK III All, MLN IN ENGLAND AND WAUS Caute of Dcjlh No. el D en-tMM|I .SiTAritr<oanM Eoiwcutl 1DtllcrcAci OH No. | CflglafMl Observed Obtened anti and Wale frccled Hate | Value or PI over the past 30 years is certainly due lo improve ments in diagnosis and in therapy (Doll, t9S.it. Even, however, if it were postulated that the whole of the recorded increase between 1931 and I9SI t u , spurious and that (he real mortality from the divea>< throughout was that ascribed to it in 1951. the expected number of deaths is increased to only M and the observed excess is still grossly significan!. Lung I l n u r ' ; ilk meniion o r boMo.it.. II mihwii mtniHMi wf i\b<iunit 0 Qihtr irkfH/jtwrj dtfivt (acM* i*l jMilmyiutf lubtrwvJom) and (iitftoviKtilir dtW4i4i : llh awAHAAOftb(1l(hil 14 iibuul anaihiai avbniifwi O8 V > <0 000001 01 / 7 For the actual number of lung cancer eases to be * little in excess of the expected os to be reasonable attributable to chance, it would be necessary for the expected cases to be 6-2, that is 5-6 times the numher estimated on I9SI rates. In other words, it would bt necessary to postulate that in 1951 (and throughout KtopUimt other than lung confer 4 Allother Oica>ct.......................... 4 3) 4 3 y >o-i the previous 20 years) there w as 5.6 times as much cancer of the lung as was rccognircd in I*>31. Allctuwt............................. I 3 f j 4 i <0000001 which would mean that the condition would have 9 o m ( im ftith iM tm oiiiri lubcrculouv fllKlusJtAf Wo MM (btftit of OM>(lh4|UI M(l WpU* (itn iM ) in h u h isIm in M t m i p ristA i b u t m i m h Umw| I iI to biv been i contfibuiory cium o f tuih, to have been present and capable of detection it over 20% of all men at death. Moreover, even it this were so, it would still not account for the fait that all the eases o f lung cancer were found i.s an increased mortality from lung cancer, other association with asbestosis. respiratory diseases and cardiovascular diseases, in x It is, therefore, concluded that the fourth explan association with asbestosis, but that their mortality ation is the most reasonable one and (haLthc asK-sm from other diseases was dose to that expected. workers who had worked for 20 o r more years in the Four explanations of the findings arc possible: . **scheduled areas *' suffered a notably higher nk 0 ) that all the men who had died of lung cancer were from lung cancer than the rest o f the population. recorded because of interest in the condition, but T o test if the risk has altered since the 1931 that some of the records of other men dying of other regulations were introduced, it is n o t only necessary diseases or still alive were omitted, with consequent to make allowance for duration o f employ mee: underestimation of the expected number o f deaths ; before the end o f 1932, but also to allow for the id (2) that lung cancer was incorrectly and excessively ages and for the total durations o f their employmcr.: diagnosed among the asbestos w orkers: (3) that 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 Ungland and W ales; o r (4) longer and lived to be older. O n the other hanJ. 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 .m2 It certainly cannot be claimed that the records o f Wales since the non-industrial risk has boo. sho-.m the Personnel Office were necessarily cmplete, hut lo be small in comparison w ith the industrial one. they were believed to be complete and no deficiency The data required for comparing the risksanvong men on this score would account for the total excess of employed fur under 10 years, for 10 to 14 years. ar.J deaths unless it were so gross Ilia! more than half the for 15 years and over in the prc-1933 conditions ore defined population had been omitted. Moreover, the shown in Table 5. The ages shown arc the ag o at number of deaths due to conditions unrelated to death of the men who have died and the ages in mid- asbestosis was close to the estimated number and this 1953 for the men who arc still alive. The expccici is unlikely to have happened unless the population numbers of men in each pre-1933 employment group had been estimated approximately correctly and the found to have asbestosis o r asbestosis and lur..: deaths from all causes fully reported. cancer are estimated by multiplying the numbers ' All the 11 deaths attributed to lung cancer were each age, total employment, and prc-1933 empluv continued by necropsy and histological examination tvvcivl subgroup by the proportions of men u.t1 so that the excess number cannot be attributed to asbestosis or with asbestosis and lung cancer in iK: incorrect diagnosis among the group o f asbestos same age and total employment group for all length, workers. Some of the excess ntay well he due to an of pic-193) employment combined. For cvanvp'e. undcrustiin.ilioit of the expected deaths since part of three out of the nine men aged 50 to 54 years wholud wC. . ;. li mtmi 0 f,<* h,' I t A i . I t i I. _ _1>, .. L-- w V,'.'' ! '*./ `'"'V' * '7 '* '* ''`l"* - ' - 1 I. " ' *V * * , V%' 1 . .'i/i*-..! :. ` !?-*: I *-! _ ; ri LUNG CANCER IN ASBESTOS WORKERS T A ftLt 2 jM o t n t o p m e n e m p l o y i 'd r o il n u n . K i. N r n n io n s m :i o u r. iv ji a n d n u m iic h s k n o w n t o h a v e a s h c s t o s is O t o s o C A N C L K IN A h b O C lA llO N W l f l l A M Ilb lO X IS D IV ID E D IIY T O T A L D U R A I IO N O P E M P L O Y M E N T IN A s c .m n u L i.u a h i a a n d u y a o b T.al I re*.iH.d j Ac ai *iU rn n l 2una XL I9S), in Sc!rU>k4 or at Arre * IA*aih 0a>| Ucarsl )S- 40 45 20 -24 SS 60 6S- TO- 75-9 4043 so SS 2S- w 65 70 75 10-4 0-M 45 5035 60-- 6570-4 Irris ili of J.mptoymcni bfura January I. 1955 0-9 Year j 10-14 Ycj re 1S+ Yaars N* !nK J No. o f 1 Men ni, N>. 1MNno . of u iih No. of Men uiih No. No. of No. or Mn with Man uh ! M | * ? Cancer j of Meo | of Lung | Asbf lu u i Cancer of Mao o f Lung Asbes to* Cancer ofLung 1 1 1 0 mm 4 W mm 1 1 0 MV mm 7 1 0 0 1 | I ) 2 -- J 1 | 2 2 2 5 2 t 0 0 0 1 1 mm 1 t 1 1 0 2 0 mm 0 t 1 1 0 0 mm 0 mm MM 1 I 1 1 -- 0 -- -- 0 -- s 0 0 mm mm to 2 mm 2 1 | 0 -- mm 6 2 1 0 0 0 0 mm MM 4 1 4 0 1 1 mm J -- mm 1 1 0 J 2 1 1 -- mm 1 1 1 0 0 0 0 mm 0 MM 1 0 0 0 -- mm 0 mm . 1 1 1 0-- mm 0 mm -- 1 0 _ 2 mm 0 mm 0 *M M. 2 MV 5 mm 2 -- --I t . mm 1 mm 2 2 1 1 mm 0 mm M- 2 1 0 -- mmm 0 _ mm 0 0 MV 0 -- -- 0 -- 1 1 -- A ll Lengths o f Employ* mens before January I 1952 No. No. of No. of Man t*iih Man ilk of Mao Asbes to* Cancer of Lung 2 1 mm s 1 1 2 1 9 1 2 7 4 0 2 2 0 2 1 1 1 1 1 1 -- 5 0 mm 12 2 | 6 2 1 IS 6 0 7 4 1 2 1 1 0 0 I 1 1 0 2 0 M, 1 0 mm S 2 1 y 1 0 0 mm i 1 -- 55 0 mm 0 1 --m mm t 0 mm 60 0 mm 0 mm mm mm i 0 mm r 65-9 0 -- mm 0 mm -- 2 mm -- 2 0 -- r 55 f 1 1 0 mm mm 2 1 mm J 40 7 ^m 1 1 0 mm . 1 45 19 2 mm 2 1 1 1 1 1 22 5 2 kacibs o f SO- II 4 1 1 J t 2 2 2 24 10 4 .ape) m en! 55 12 4 mm II 5 0 5 2 1 21 12 1 n a 60 7 1 mm 2 2 0 7 2 1 16 I 1 s.h(4uk4 65- S 0 1 t 1 2 1 1 7 2 2 i r 70 0 0 mm 0 mm mm ) 2 0 2 2 0 >.+) 75- 1 1 mm 0 -- mm 1 1 1 2 2 1 10-4 0 mm 0 -- -- 1 0 1 0 -- A ll a tr e 61 u 1 2 1 14 26 16 i in * .tn employed for 20 to 24 years in Ihe areas in Uich (lcy might be exposed to asbestos dust were >uno to have asbestosis and lung cancer. Since tree men had worked for under 10 years in the prei)3 conditions three had worked for 10 to 14 years, ltd three had worked for IS or more years, the \pcctcd number of cases in each of the prc-1933 nploymcnt groups would have been the same, x 3,9, or 1. In fact, the numbers of eases found ere 0 ,1and 2. The total numbers expected in each re-1933 employment group are obtained by adding ic numbers calculated for each of the age and total mploymcnt groups within it. The results arc as Hows : The differences between the numbers of mcn therved and the numbers expected in each employ ant group, had the incidence of the conditions :maincd steady throughout, arc statistically signi- ficant (total asbestosis, x* ** 7*32 n * 2, P = 0*025; asbestosis and lung cancer, x* *8*74, n ** 2, P 0-01*). They are highly so if the trend, that is. T otal number o f mao' l observed u h asbestosis 4I rap rrrrd Number o f men v iih l 1o b u n e d asbesto* and lung j f \ p e r ir cancer Lentil o f Empio) meni before iiM u r y 1.1952 Under 10 Years 10-14 Years 12 Y e a n and Osar 12 14 16 JO-2 JO-2 t 2 7 J4 7*2 2-J T h< piN numbers o f lung cancer i n small am i iha probabiliiy that ilie difference* ( u u U sure by chanct has osuiiw coUy been ttmclMt. but not M iw u tly , underestimated. I f a ll men u h more than 10 >cars nte-IVJJ empioyment are grouped l o p i i u r and Yares* correction mad for small num bers x* ** S S L s I, f O O L . . . i * ' 1 vr. j a .* i I f . - s ' xT.-`w:r. A v. '_ V *?* At I .t .. * ,,. Ur* *>i** *. ' --`*v*,'1i 4!>.<:*. -.v: *cs.r**i 'K* * ^ , ' > ' a-V -L-3C \ S`` L ?>s -V^V w s . %._ A .V '* ; v / y ** V> U.>. f . - V < -i ** ?-. -c *.*. s^.; . 'v . r.v < -, r~cUJi.,,\y a ` .V Tm wisxr H n v d im tS f * 86 BRITISH JOURNAL OF INDUSTRIAL MEDICINE the biologically important reduction in the propor tion between observed and expected numbers as the length of pre-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 number of years during which men were exposed to the pre-1933 conditions has decreased.* The extent of the risk of lung cancer over the whole period among the men studied appears to have been of the order of 10 times that experienced by other men. This agrees well with the data reported by Merewether (1949), but it is somewhat greater than that suggested by Gloync's data (1951). The great reduction in the amount of dust produced in asbestos works during the period has been accom panied by a reduction in the incidence of lung cancer among the workmen so that the risk before 1933 is likely to have been considerably greater--perhaps 20 4 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 men nt risk, who have been exposed to the new conditions only and who tiavc been employed for a sufficient length of time, is at present too small for confidence to be placed in their experience. It is dear, 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 men in the country at large has increased sixfold. Summary 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, IS times in association with asbestosis. All the subjects in whom both conditions were found had started employment in the industry before 1923 and had worked in the industry at least nine years before the regulations for the control of dust had become effective. 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 any the mortality among them compared with that which would have been expected on the basis of th.* mortality experience of the whole male population. Thirty-nine deatlis occurred in the group whcrca; 15*4 were expected. The excess was entirely due to excess deaths from lung cancer (II again-.; 0*8 expected) and from other respiratory and cardiovascular diseases (22 against 7*6 expected). All the eases of lung cancer were confirmed histo logically and all were associated with the presence of asbestosis. From the data it can be concluded that lung cancer was a specific industrial hazard of certain asbestoworkers and that the average risk among men employed for 20 or more years has been of the order of 10 times that experienced by the general popula tion. The risk has become progressively less ns tl-.c duration of employment under the old dusty con ditions has decreased. I would like to offer my thanks to the management the firm concerned for permission to carry ont thu work and to the Medical Ofliccr.and mcmbc:s of the statT of the works where the men were employed, who carried out the greater part of Use work on which this report ibased. R eferenccs Alberto InduMry Retaliation! (1931). Statutory R uin and Order. 19)1. No. IMO. H.M.S.O, London. Boemke, F. (195)). A M . M tehe^ 7. 77. Cartier, f . (1952). Areh. indiate. t t y f ^ S, 263 (contribution t> diwuuionl. Council or the International Oresnicnioni of Medical Scici (195)). A tta Un. tnt. Canee.. 9, 44). Doll. R. 1195)). M l. nteJ. J,, 2. 321. Gloyne, S. R. (19511. lancet, 1 .110. I l i . x i , W . C. (I952L Prneeedinta o f the Seventh S m m t S*----- slum. To be pubtirlwd. Lynch, K. M.. and Sm ith. W. A . (19)5). Amur. J. Canerr, 24..**. M rftw tllK r, E. R. A. ( 1949). Annual Repaet o f the Chief Intis*: effa cto tiet foe the fette in i:. H.M.S.O.. London. Nordntann. M.. and Some. A. (1941). Z . Keehtfueten* 31. In). Smith, W. C. (1932). Arch, imhntr. H ie ., S, 2d9. Stock!. V. (1932). M l. J. Contee, 4. 99. Vmwakl, A. ).. and K arr. ). \V. (|9 J* ). Amer, J, Path* 14. 4 Warren, S. IW4>. O r * Meti., S. 349. 1 J' m> ?iiir`o.m*- )r ' n * * < . * , * ' i*. *r ' .o . ^ i i* y . R a l Ah . ) ' , ' k* ** i rnv-- ` / .** ' v - -- '. ! ' S `*. * ' \ T . ^>StF *w l-.,.. _ _ . .V -