Document Yrv8L5wBp48YE1zVybY89nxdV

Hcimiirfri ri** Ittunuii r* Th* A"i^rr<in Mttitcti A*'`OCMt**n ri > />'.'* I .( ,,'f/, ..,1. /fl/'.f/J ConyNC^f VC-S. h'j Auu rtcUH SttdtCAi AfWtCMlNVfl ^ IST00 1584 Asbestos Exposure, Smoking, ancl Neoplasia living ] ScliknfJ. MD: . Curler Hainmmid, SrD; and Jacob Churg, MD Asbestos iRSuiition workers, as a group, have a high due to chance, the number of such deaths being risk or s/ing of bronchogenic carcinoma (about seven or small. During the latter part of the study, we ob e ght times expected). We have observed 370 such work- tained information on the smoking habits oi most men from Jan 1. 1963 to April 30. 1967. Our findings of the survivors, but we could not obtain reliable inoicate that asbestos exposure alone is not the entire information on the smoking habits of those who explanation. Of 87 noncigarette smokers, none died of had died at an earlier date. Therefore, we could broncnogemc carcinoma. Of 283 workmen with a history not at that time investigate death rates in rela of regular cigarette smoking, 24 died of bronchogenic tion to smoking habits and exposure to asbestoi carcinoma, although only three were expected to die of dust which were considered both separately and this disease. Calculations suggest that asbestos workers jointly. wno smoke have about 92 times the risk of dying of There is abundant evidence that cigarette smok bronchogenic carcinoma as men who neither work with ing leads to a high rate of death from lung cancer asbestos nor smoke cigarettes. We conclude that asbestos in the absence of occupational exposure to asbestos eiposurc should be minimized, that asbestos workers who dust.'' Our findings outlined above suggesred (but do not smoke shouid never start, and that those now did not prove) that exposure to asbestos dust may smoking should stop immediately. lead to a high rate of death from lung earner in the absence of cigarette smoking. If the latter be n 1964. wc reported on deaths occurring between so, then the combined effect of both types of ex I J.-.n 1. 1943. and Dec 31. 1962, among 632 posure might or might not be equal to or greater memners oi the International Association oi Heat than the sum of the two effects. On the other hand, and Frost Insulators and Asbestos Workers.1 All it was possible that exposure to asbestos dust in oi these men had been occupationally exposed to creases the risk of lung cancer among cigarette asbestos dust for many years. Their death rate smokers but does not lead to lung cancer among from lung cancer was found to lie 6.8 times as high nonsmokers. ns tr.at reported ior the general white male popu The present study was undertaken primarily lation of the United States during the same years, to investigate these possibilities. In addition, we with age taken into consideration. Three of the wished to obtain more information on the occur men (iied oi diffuse pleural mesothelioma and one rence pf mesothelioma and gastrointestinal cancer died oi a neoplasm histologically suggestive of peri among asbestos workers. toneal mesothelioma. This was of interest since mesothelioma is a very rare disease in the general Material population but is reported to be associated with From records of New York Local 12 and Newark. exposure to asbestos dust/ In addition, their death NJ. Local 32 of the International Association oi rate nom cancer of the stomach, colon, and rectum Heat and Frost Insulators and Asbestos Workers, was manor than expected; but this may have been I rom Hi** iV|*Artmcu of Community Medicine. Mount Sintu ''I..., ... Mitiumr il>rn. S>Ukoi2 ond ChurtfJ. and me Depart* I.* mi ... i ...tirmioiucv Anti Sutitues. American Conetr Society Oi .i.iiioiui. Nc* York. i:. ... i ,-tore .i joint mcfimff of the Section on Di*e*hes of the On vi ,m me St non on Preventive Medicine end the American t' ... ..I n,, w, i'hvairiAnt At the llGth Annual convention of the < n Ml.hr.*). Av^cinnon. Atlantic City, N.J. J.mc ID. 1007. rcnui'Ms to Mount Sinai School of Medicine. 100th ' .... imiii Avenue. .New Yora 1 tDr. deiikoU;. a list was made of every' man who was a member of cither one of these locals on Dec 31., 1942. or who joined between that date and Dec 31. 1962. No one was omitted regardless of his subsequent work history. Personnel data from union records indicated that of the 632 on the union rolls on Jan 1. 1943. 339 oi the men had first been occupationally exposed to asbestos dust prior to 1922, ana an additional JAMA. Aon I 8. '.968 Vol 204. No 2 DOW 06867 ASBESTOS EXPOSURE--SELIKOFF ET AL 107 STOOI1585 203 men hnti first been ex posed between the be- Table l.--Subiect* Cios*i`:eS by A-e as e: Jan 1. 1953. and by Tears From First Occupations! Exposure to Asbestos Oust uo to Jan 1. 1963 iinmne or 1023 and the ettd of 1042. All of these men were successfully traced through Dec 31, 1962. and 262 of them were found to have died up to that time. Of the 262 deaths, seven oc curred prior to the 20th anniversary of the man's A*. Tf ivn 40-44 45-49 50 54 55 56 90 64 9569 7074 75-76 0044 Total No. of Sutioctt 2 13 i: 109 60 42 49 is 21 4 20-34 2 :2 :7 2S-2S ; 2 t 1 1 30-34 ii so 16 3 l 15-16 :s 34 n 10 3 40-44 . - a 19 11 12 1 1 <S4t 1 8 18 6 5 1 HO. Of 90+ 52 Ma 1 2 11 11 16 2 17 :7 18 :s 8 23 first exposure to asbestos Tolol 170 ii in SO 99 16 94 dust and 253 occurred after the 20th anniver sary. Thus, of the 632 men, 370 were still living on Jan 1, 1963. These 370 men were the subjects of the pres ent investigation. Table 1 shows their age distribu tion as of Jan 1. 1963. and the lapsed time from first exposure up to that date. All of them have Table 2.--Subiects Classified by Age and by Smoking Habits on o- about Jan 1.1963 ISIS 40-44 <5-46 50-54 55 56 60 64 6566 70-74 75-76 10*64 Total No* 2 13 12 106 60 42 49 38 21 4 Nw SmgkH i 2 2 12 6 7 6 7 i 2 Cigar Only 1 6 5 4 6 7 7 1 Cl- , cfrarlt4 Smokora- 1 2 9 26 16 1$ 17 12 6 1 Current Curette Smeken* 1-6 o Oar ..a aaa 3 1 i aaa T1 10-16 a Oar ., . 5 1 4 4 1 -- 20-16 a Oay a. a 6 12 11 20 11 9 4 3' m 40+ a Oar 000 4 12 2 10 4 9 i 3 av. been traced, and 94 of Total 170 48 16 101 s 17 67 61 them were found to have died during the four-year iiKiufl#* tmoMcft who jito tmefcM pip** or cigprt. * and four-month interval from Jan 1, 1963, to April 101 were excigarette smokers, five currently smoked 30. 1967. one to nine cigarettes a day, 17 smoked 10 to 19 Beginning in October 1962, we made arrange cigarettes a day, 97 smoked 20 to 39 cigarettes a ments to examine these men periodically, once day, and 63 smoked 40 or more cigarettes a day. every six to twelve months; the interval depended The smoking habits of the 370 subjects were upon age and physical condition. The examinations compared with the smoking habits of a large num include chest x-ray films as well as physical ex ber of men selected from the general population.' amination and cover past and present smoking There were proportionally more cigarette smokers habits, occupational history, medical history, and among the 370 subjects than were found in the current physical complaints. Altogether, we have general population sample; age was taken into examined 338 (91.4s) of the men at least once consideration. and have repeatedly examined most of those who Causes of Death.--A copy of the death certificate are still living. was obtained for each of the 94 deaths. In addi Information on smoking habits was obtained by tion, we examined hospital records, postmortem personal interview with the 338 men who were ex findings (41 cases), as well as the surgical and amined. Of the 32 men who were not examined, pathologic repons when surgery was performed (39 six told us their smoking habits by telephone and cases). We also reexamined histologic specimens. five gave us the information by mail. The local It was found that the death certificate was inac union secretaries (who personally knew these men curate in 14 instances. However, this did not alter wcil) ascertained the smoking habits of 18 men, the picture as much as might have been expected and family members supplied the information on since there were several compensating errors. For the remaining three men. This accounts for all of example, in one instance the death certificate in the 370 men. Table 2 shows their smoking habits dicated bronchogenic carcinoma as the cause of on or about Jan 1, 1963, the men being classified death while a review of the histologic specimen bv their ages on that date, even though some showed that death was due to pleural mesothe changed their smoking habits between 1963 and lioma; but in another instance exactly the reverse 19G7. was found. Likewise, review in one instance re Of the 370 men, 48 never smoked regularly, 39 sulted in changing the reported cause of death i-mokcd or had smoked pipes or cigars but never from bronchogenic carcinoma to cancer of the >mnkcd cigarettes regularly, and 283 had smoked stomach with metastasis to the lungs while review cigarettes regularly. Some of those with history of in another instance resulted ir. exactly the oposite cigarette smoking aiso smoked pipes or cigars. Of change. The 94 deaths were ascribed to the follow the 283 w;;h a hi.-tory of regular cigarette smoking, ing causes: bronchogenic carcinoma. 24: pieural JAMA. Apr.) 8. 1968 Vol 204. No 2 DOW 06868 IST00 1506 ASBESTOS EXPOSURE--SELIAOFF ET AL ,ind Eapcetcd Number of Death* Amor.j /sjca:;* v.'orKert During tli 52"on:n Penoo Coutt of Ooath *i e*"** * *** rAncf Iirr O'tur*. broneftwt. " .ifl U -CPfl F'itr"en mciotn"4*na C v'Cff CJ*CF of CO0*6 roclum 'ictr of on otnof vtM combtnoO <4MtlOt>l M0* o*0 Citcuioiory oitoato including H'OM oit of**' cowiot of ototft T*tl. all MUM* Obtcrveo doom* 49 :r :* 0 7 3 ft 7 IS :: 94 CoecteO DoOtftft* St :3 * ; : St 12 4ft :s.s 134 *73 Boto use" US mortality o.la di*rt(*raiftf tmoain* naO'tt. un.no Sniot data not ayaiiaoio. But t.(gra anouio bo only ti'fiiiy lota man 2J. lun.ito Slant can not aut'iBBia. But thoao art roro cauttt of ooailt n (tnorai population. mesothelioma, three; peritoneal mesothelioma, sev en: cancer of the colon, four; cancer of the rectum, one: cancer of the stomach, three; cancer of the pancreas, two: cancer of buccal cavity and pharynx, two: cancer of bladder, one; cancer of undeter mined primary site, two; asbestosis, 15; cor pul monale. one; comary heart disease, 17; congestive heart failure, one; cerebral vascular lesion, two; aortic aneurysm, one; cirrhosis of the liver, three; bronchopneumonia, one: encephalopathy, one; acute pancreatitis, one; Wegener's granulomatosis, one: ami accidental fall. one. i'.v/)ixted Dcaf/is.-For purposes of comparison, v\e wished to ascertain how many of the 570 sub jects would have died during the 52-month period i Jan 1. 1965. to April 50, 1967) if their agc-spccific death rates had been exactly the same r for the general white male population of the United States. For this purpose, we made use of the United States 1964 life table for white males; this provided the most stable basis for comparison. It should be noted that for white males total death rates and death rates from respiratory cancer were slightly higher in the industrial states of New York and New Jersey than in the United States as a whole." ' On the other hand, respiratory cancer death rates in white men aged 20 to 64 are reported to be a trifle lower than average among laborers, not elsewhere classif.ed employed in construction work." From the life table we determined for each of the 370 men the probability of his dying within a pe riod of 52 months, considering his age on Jan 1, 1963, and assuming that the life table probability applied to him. Summing these probabilities for the 570 men yielded an estimate of the "expected" number of deaths under the null hypothesis that the age-specific death rates of these asbestos work ers arc the same as for United States white males in general. The computation indicated that 47.3 deaths would have been expected. Next, we wished to estimate the expected num ber of deaths from each of several causes. For this, we made use of the percentage distribution of deaths by cause of death among United States white males of various accs nuring the year 10*34 as reported by the National Center for Health Sta tistics. These percentages were then standardized tor age according to the age distribution at time of the 47.5 expected deaths. The results are shown in Table 3. Expected vs Observed Deaths.-As shown in Table 3. there were 94 observed deaths (ie, 94 of the 370 asbestos workers died) as compared with 47.5 deaths expected on the basis of the age-specific death rates of all white males in the United States in 1964. Thus, there were 94 minus 47.5 - 46.5 excess deaths. The excess deaths were due to bron chogenic carcinoma, mesothelioma of the pleura and peritoneum, asbestosis, and cancer of the stomach, colon, and rectum. Cancer of Lung, Pleura, and Trachea.--In pub lished mortality data for the United States show ing deaths each year from various causes by age, sex, and race, the following diseases are combined: cancer of the lugg.(including sarcoma of tne lung), cancer' of the bronchia, cancer of the pleura, and cancer of the trachea. For this group oTdiseases, there were 27 observed deaths and only 2.3 ex pected deaths, a ratio of nearly 12 to 1. It is well known that, for the United States as a whole, all except a very few of the deaths .re ported in the combined category are due to t&QQ^ chogenic carcinoma. Thus, it may be assumed that "there'were close to 2.3 expected deaths from this cause as compared with 24 observed deaths, a ratio of over 10 to 1. Mosothelioma.-Tcn of the 94 observed deaths were due to mesothelioma, three were due to pleural mesothelioma, and seven were due to peri toneal mesotheliomas. This is such a rare disease that if the 370 subjects had been selected as a random sample from the general population, one would not have expected any of them to die of mesothelioma within a period of 52 montns. All three of the men who died of pleural meso thelioma had a history of regular cigarette smoking. Of the seven who died of peritoneal mesothelioma, one never smoked regularly, one smoked only pipes and cigars, and five had a history of regular ciga rette smoking. Cancer of Stomach, Colon, and Rectum.--In our earlier study of asbestos workers,' there were more deaths than expected from cancer of the stomach. colon, and rectum (9.4 expected, 29 observed). As compared with a total of 1.8 expected deaths from these causes, there were eight observed deaths in this study, due to cancer of the following sites: stomach, three; colon, four; and rectum, one. Al though this bears out our earlier findings, the num ber of deaths from these causes was so small that we still refrain from drawing any conclusion at this time. Asbestosis.--Asbestosis accounted for 15 of the 94 deaths. While it is not surprising that deaths from this disease occur among men exposed to asbestos dust, attention must be called to the fact JAMA. April 8. 1968 Vol 204. No 2 DOW 06869 IST00 1507 AS8ESTCS EXPOSURE-SELIKOFF ET AL 109 that these subjects were pr.tr.ahly insulation work* ers. While all of them were occupationally ex* posed to asbestos dust, their degree of exposure was light as compared with the degree of ex posure of asbestos miners, processors, and weavers in earlier times. Bronchogenic Cardnoma.-Bronchogenic car cinoma accounted for 24 deaths while only about 2.3 were expected on the Tabl 4.--Estimated Number of Lung Cancer Oeatns Expected to Occur Dur r,r a Period of 52 Months per 10.000 Men Living at the Start of Period: by A(;e ar.o by Smoking natiits- Aft. tf Uan 1,19*11 39-39 4044 1141 u-u SS 99 66-64 l-*9 70-74 -7l 0*4 ft.puiarly 0 2 2 1 * If 14 12 21 25 Pip*. Ci-r Only .... ..t 2 12 IS 3 12 92 91 12 IlCifirittl Smiirsl S 7| ;a 22 11 71 7 100 ICO 14* 14 o...r ... 21 to 103 ... ... Curr.nt Cmarctl. Imottrw 10-19 . O.y ... . 44 ii. 197 20* III ;s.v . O.y 13 39 *t : 17 190 301 281 341 $ Qr 1$ 46 90 1*9 394 390* <90* 12* '*** upon sta Ircm pr.ie.ctiv. ttuy ,th .Piu.tm.nt far US mertainy ipri.no. tcii.pmi motcm rates amittce for caiifsnee with no susiecta m this ttuay. See Tael* 2. tmciuaet eicsrette smeeera wh* else smekse pip. w cifer. mm with s histerr at eni* cieerette tmeking neve n.gn.r lung cancer rates then anewn here. I Salat astamee ey ameetnmg tne gate. basis of general United States mortality data for divided into many five-year age groups, some of the white males. However, as previously mentioned, subgroups contained only, a small number of men. evidence at hand suggests that there were propor In consequence, the lung cancer death rate was tionally somewhat more cigarette smokers among statistically unstable in some of the very small sub the 370 subjects than among white males in the groups. In three instances where the observed rate United States as a whole, age being taken into in a small subgroup appeared to be badly out of consideration. This might have partially accounted line, we arbitrarily made an adjustment to bring it for the high bronchogenic carcinoma death rate of more into line with adjacent figures in the table. the subjects. For this and other reasons we made These adjusted figures which are indicated with estimates of the expected number of bronchogenic symbols in Table 4 cany very little weight in the carcinoma deaths, the smoking habits of the men final calculation. All of the rates were then ad being taken into consideration. This was done as justed as follows: ' follows: Lung cancer death rates in the United States Data are available on lung cancer deaths in re have risen steadily year by year and were higher lation to the smoking habits of 440,000 men en in 1964 than during the period 1960 to 1964 as a rolled by American Cancer Society volunteers in whole. Furthermore, in the study described above, a prospective epidemiological study between Oc we avoided enrolling seriously ill people and. as ot tober 1030 ami March 1900 and traced through the cut-oil date for preparing the computer tai>e. Sept 30,1064. Causes of death were ascertained from we had not yet received death certificates ior all death certificates, but whenever cancer was men of the men now known to have died during the tioned on a death certificate inquiry was made of specified period of time. For these reasons, lung the physician who signed the certificate. In case cancer death rates in the study population were of disagreement between the two sources of infor appreciably lower than those reported lor white mation, the physician's statement was accepted. males in the United States in 1964. To compensate For the purpose at hand, we only made use of data for this, we raised the rate of each individual smok covering the 52-month period beginning on June 1, ing category so that the total lung cancer licnilt 1060, and ending on Sept 30, 19Gi. The number of rate (disregarding smoking habits) in each live- lung cancer deaths occurring during the 52-month year age group would be the same as that ni all period was divided by the number of men alive at United States white males t based upon tiu: I'Jb; the beginning of the period. This was done by five- life table and the 1964 distribution of deaths by year age groups for men in each of the following causes of death). The results of these compui-uions smoking categories: (1) never smoked regularly are shown in Table 4. (It should be noted that (nonsmokers and occasional smokers being com Table 4 shows only such rates as were required lor bined); (2) history of regular pipe or cigar smok iurther calculations.) ing, past or present, but never smoked cigarettes The rates shown in Table 4 were then applied to regularly; (3) excigarette smokers (including those the number of asbestos workers .-hown in each oi who had smoked or currently smoked pipes or the corresponding internal ceils of Table 2. This cigars); and (4) current regular cigarette smokers yielded an estimate of the number m' !uu:: cancer (including those who also had smoked or currently deaths expected to occur during a *2-monih period smoked pipes or cigars). The last of these cate among the 370 asbestos workers cla--.iicd by their gories was further divided by current number of smoking habits. By "expected" mnab.-r. -u: to cigarettes smoked per day: (4a) one to nine ciga mean an estimate of the number of lung cancer rettes a day; (4b) 10 to 19 cigarettes a day; (4c) deaths which would have occurred undi .- s:;.: nail 20 to 39 cigarettes a day; and (4d) 40 or more hypothesis that asbestos workers do nut i;.:T; :mnt cigarettes a day. Since the men were divided into other men in respect to :::c;r 1,... itn seven groups by smoking habits and further sub rates, both age and smoking being taken ,AMA. April 8. 1968 Vol 204. No 2 DOU1 06870 IST00 1508 no AS5E570S wX'CSURt--SctiKOFr ci AL ,,a.c 5.--C.-;;rvcc ana Expected 3rc.nciicser.ie Cjrci.-.err.s cy Snoxrnj Habits* for 370 Asbestos Workers Smaauta HaMa *.cvr smoittf regularly r^otonr o1 0*09. egar tmokiftg e*4y hittory of regular Cigarottt amoarngt ObtcrvcO dattrtt 9 0 24 toeetcb Oaatna 0.05 3.13 2.91 Tetal u S.1* *3aaad upon oata m Tab:# 2 and Tabid 4. nc.udti egafand amour* ono atao amoaod piaa or cigar. Tsbi 6 --csscctdd ana Observed Caatns Among 632 Assettos Workers Eaoosid to Asbtsto Oust 20 yaars or Lon;:r Total eaatna: au cauaaa ClbKtM ODtarvM Total cancar all titaa ElOMtlO O&iorved Caneir af Iuhb. tracltaa. alaura Eaocto* Ofttarvod Cancor e* ttomten. cote*, return CsDOCtOO CbiirvM Canetr ail stnar titaa camtena* ElOKtM 00*rv#d A|0tt0*i9 EaOCCtOd Otto rued All other eauoeo Ciotetio GOterved 1942-19*2 202.9 2SS 19*2-19*7 19T43o*t*a9l47 47.1 211 94 24* J4.9 l.t 4S4 99 49 144 U 2J 49 27 U 72 9.4 1.* I1J 29 * 17 :o.s i) 29 21 14 39 00 0 12 19 27 147 :t9 239J 149 10 179 into consideration. The results are summarized in Table 5 which shows the expected and observed number of lung cancer deaths in each of three smoking categories. Taking smoking habits as well as age into con sideration (Table 5) a total of 3.2 bronchogenic carcinoma deaths were expected whereas taking only age into consideration 2.3 deaths were ex pected from this cause (Table 3). Thus, perhaps one of the excess bronchogenic carcinoma deaths might be attributed to the fact that there appear to have been proportionally somewhat more ciga rette smokers among the 370 subjects than among men of the same ages in the general population. The following statements are based upon the data shown in Table 5. Twenty-four deaths from bronchogenic carcinoma occurred among the 370 subjects compared with only 3.16 expected, a ratio of about 7.6 to 1. This is slightly higher than found in our earlier study which indicated a ratio oi 6.6 to 1 (not taking smoking habits into considera tion). It should be noted in this connection that the 370 subjects in this study had been exposed to asbestos dust somewhat longer than the subjects oi our previous study (the present 370 subjects are survivors as of Jan 1, 1963, of subjects in the previous study). Of the subjects who never smoked regularly and those who smoked only pipes or cigars, none died of hrom nogi nic carcinoma whereas 0.1S of these men wi.rc < ctcn u> die of lung cancer. This sug- tr.:.'. ';.*< k, . i.c -.ios dust docs not in crease tr.u risk of hroncnogunic carcinoma among incr. who never smoked cigarettes regularly. Kowever, considering the smail number of such subjects in this study, we only conclude that exposure to asbestos dust does not greatly increase the risk of bronchogenic carcinoma among men who never smoked cigarettes regularly. Twenty-four of the men with a history of regular cigarette smoking died of bronchogenic carcinoma whereas only 2.93 were expected to die of it, a ratio of S.05 to 1. From this it appears that exposure to asbestos dust greatly increases the risk of lung cancer among cigarette smokers. Now we may ask how greatly is the risk of bron chogenic carcinoma increased by the combined ef fects of cigarette smoking and exposure to asbestos dust. To answer this question, we applied rates shown in Table 4 for nonasbestos workers who never smoked regularly to the number of subjects with a history of regular cigarette smoking as shown in Table 2. This indicated that only 0.26 of the subjects with a history of regular cigarette smoking would have been expected to die of bronchogenic carcinoma if they had never smoked regularly and had never been occupationally exposed to asbestos dust. Since 24 of them actually died of this cause, the ratio of observed to expected deaths is 92 to 1 (ie, 24 divided by 0.26-92). This appears to in dicate that cigarette smoking plus occupational exposure to asbestos dust increases the risk of bronchogenic carcinoma by a factor in the order of magnitude of 92 to 1. It should be noted that this estimate docs not take current amount of cigarette smoking into consideration. Comparison With Earlier Findings.--As explained, we started with a cohort of 632 asbestos insulation workers, the entire membership of the union locals on Jan 1, 1943. We have now traced each man through April 30, 1967. Table 6 shows the observed and. expected number of deaths for each of two periods (the first, 1943 to 1962, being previously reported1) and for the entire period. In respect to respiratory cancer (lung, trachea, and pleura) and in respect to cancer of the stomach, colon, and rectum, the findings in the two periods are in close agreement. Comment ' The increased risk of neoplasia (mainly broncho genic carcinoma and mesothelioma) among insula tion workers reported here should be evaluated in the knowledge that these men have comparatively light exposure as asbestos trades go. Primarily em ployed in construction work, many of the materials they use contain little or no asbestos and others have only 3% to 15%. Conditions oi work vary; these men often work outdoors unlike asbestos operators in factory work. Comparatively iew dustexposure surveys have been made in this trade but their results have generally been within the 3 mil lion particles per cubic foot permissible limits cur rently accepted by the American Conference of Governmental Industrial Hygienists.'Nor have JAMA. April a. Vo1 204` No 2 DOU 06871 STOO11589 at wS<jRc*SwL*kOF^ ti Ill addition?.! p.'itrr.:i.*.!ly identified among :?..*.- I{* nvicr or . 1: " >ii;7(.r; ns. drgrt. rl- :... I'xp'ouri: in ii.: ..... resulted in '.n.-iricr;:n!.r !;:r" :v t r.-.:. dtv<i< .i;:!,: lung < i.r o..*.er.*. parauccouse a- iii '.u.-i-i was common ;>nr; *o -cverc as to cause d, atii <>( :;ii! f.po.-tfi workers xc.ore tncv cou.d i:ve long --r.oiiah to develop lung c.'.r.r^r. Once exposure ..w r< -duc-cd !<y improved industrial hygiene prac tices. early death from asbestos.* >.'.arpiy cimin- i>hco ana lur.g cancer became common." In any case, heavy exposure not likely to be the most important problem in the future, unless there he sheer carelessness or unconcern. Rather, iight exposure, similar to that in insulation work, will lie much more common, both ir. direct asbestos working trades and as the result of indirect occupa tional exposure, as in the construction and ship building industries. There is another type of "light exposure' which may a fleet many more people than those industrial ly exposed. In the past several years, it has been demonstrated that asbestos bodies can be found in the lungs of 25% to 50% of adults examined at autopsy in large cities, such as Belfast. Northern Ireland, Capetown, Republic of South Africa, Miami. Fla, Pittsburgh, and Montreal. This is presumably due to "asbestos air pollution" by fibers derived from industrial "spillover" (as dust from construction sites or factory wastes) or from end-product use. Such community asbestos air pollution may be important since there is already evidence that in certain circumstances, as living within half mile of an asbestos plant or in the household of an asbestos worker, intimate environ mental contamination can be associated with some risk of mesothelioma.'* What is not now known is whether the minimal amounts inhaled by the gen eral public carry a similar risk.'* Nor do we know whether inhalation of the very small amounts of asbestos present in the air of some communities is associated with a special lung cancer risk in cigarette smokers (or. conversely, whether cigarette smoking makes the inhalation of very small amounts of asbestos particularly hazard ous). It will be important to ascertain whether such cocarcinogenic or potentiating or precipitating rela tionships exist because, with the rapid growth of asbestos use (500,000 tons per year world produc tion in 1930 has risen to over -1.000.000 tons per year now), it may be difficult for cigarette smokers to avoid inhaling air contaminated with asbestos. I: may not be easy to unravel the interrelation ships which might exist between community as bestos air pollution and cigarette smoking. Both asbestos exposure and cigarette smoking have a long-lapsed period between onset of exposure and occurrence of neoplasia, yet for current smokers these two exposures may not have begun simulta- iies.i.s.y; there was muen less asoestos used 20 to fl year* .*ro. Young-:. :\- v. no s;.-,rc smoking now Iv.vr a much greater chance of having both ex posures sirr.uit.iurmi-iv. Significance of Findin a fir ihrstns Workers.-- The import of the data reported here seems clear. There is an extraordinary risk of developing and dying from lung cancer tor -hrstos workers who smoke cigarettes regularly. In the group studied, the combination of asbestos exposure and cigarette smoking increased the risk approximately 90 times compared with men who neither work with asbestos nor smoke! Of 2S3 asbestos workers who had a history of cigarette smoking, TS died within a period of 52 months whereas only 32.4 would have been ex pected to die within that length of time if their age specific death rates had been the same as for the general white male population of the United States. Of the 78 deaths, 24 (31%) were due to broncho genic carcinoma. It is estimated that if these men had smoked cigarettes but had not been exposed to asbestos dust, oniy 2.98 would have died of bron chogenic carcinoma within the same length of time. If they had neither smoked nor been exposed to asbestos dust, only 0.26 would have been expected to die of the disease within a period of 52 months. Of 87 asbestos workers who never smoked ciga rettes regularly, none died of lung cancer within the 52-month period (although throe died of osbestosia and one died of peritoneal mesothelioma). This' finding, being based upon the experience of only 87 men, (iocs not prove that exposure to asbestos dust has no influence on the risk of lung cancer among nonsmokers. However, it suggests that ex posure to asbestos dust does not lead to an ex tremely high risk of lung cancer among nonsmokers. The conclusions are evident: 1. Occupational exposure to asbestos dust should be reduced to as low a level ns possible: but there may be an irreducible minimum level if asbestos, a very useful material, is to be used at alL Such reduction in exposure will benefit asbestos workers of the future. However, we are also concerned with workers who have already been exposed at signifi cant levels for many years. Asbestos fibers will re main in their tissues for the remainder of their lives. 2. All people incur a great increase in risk of lung cancer if they smoke cigarettes: for asbestos work ers the increase in risk is tremendous. Asbestos workers who do not now smoke cigarettes should never begin. Those who do smoke, should stop immediately. We may hope shat the decrease in risk which results from cessation of smoking among the general public' will be the good fortune of the asbestos workers as well. Thin invMiicnnon wan -uitportMt hv th Health Reasarm Gxincil of thi City of Now York. Rtftrtncts 1. Solikoff. I J.. Chur**. J.. nd jl.tmmond. iC C.. (NriipitUiei, MAM tMitfii a" (Ai-ru 1,1 *. Htlikoit l J.; Ciurif. J.: nrui H.uumonti. K-C. .sbi-.*n Kvowuri* o .inn A*-. *'* * (NUrch 10) iSKiS. JAMA, April 8. 1968 Vol 204. No 2 k- DOUI 06872 AS3EST0S EXPOSURE--SEUXOF? OT AU 112 * }f.imninun. j' C. "Smosinc in Relation lo (he Death Rates of 1 omul) V.'ii ami Women,'' in Ktudi'mintocieal Study nt Cc.icrr amt lt:n,r C: fame Dnenjre. Itcil.pvia Md: National Cancer i.i-tuittr. : *>. aionoeraph 19, pp 12?-234. t. Smnnne end Health. Itcimrt of the Advisory Committee to the Sureeon Ccneral at the IHtblic Health Service. publication U03. l.'S Dopt oi Health. Education. and Welfare. IM4. ` Haminmtn. E.C.. and (larSnkei. f,,: Chances in Gearett# Smoktnc U'.Vt.lCiWi, Amer J Public Health 33:30-43 ijan) 1C6S. V Vito/ Stctmtice of the United Stater. tittO. part A. US Dcpl of Hralin. Knur.:iion. and Welfare. 19<X>. vol i. 7 Der.th .'Tetri Protn htalienant Neoplasms. .'JIM. Public Healtn Service, publication 1113. US Dept of Health, Education, and Welfare. 1963. 8. Mertnlitv by Occupation and Cause of Death. Public Health Service. US Dept of Health. Education, and Welfare. Vita) Su- italics Division. Vital Siauaitca-Special r..;.-,r;.. !). Fleischer. W.S.. t alt A Health 5sv~ oi 1' -. .. Operations in Ccnsmieiinj Nuvat Vcsoc.s. J imdutr I 23:9-ir. I4an< 1946. ..,, _ 10. Keano. W.T ar.d Zavon. M TU; On upai-.nnal H.v.wii id Pipe insulaton. Arch Km-iron Health tttlTl-lTft < Ausi *.1. Dolt. R.: N!oftftsv From Icuntr Ginctr in A^mo* \Vm Srit J ttiduMir Med 1241*66 t Apnl* 1M1 li j.Mh 0., ^nd Anspach. .Vt.: Pulmonary Npl.wn Amonf Dresden Asbestos Workers. Ann NY Acad Sc 133^3C-'rtd iDer 31) 1965. 13. Ntwhouaa. M.L- ar.d Thompson. H.: Meaotheliomo of Pleura and Peritoneum Following Ezpoaura to Asbestos in the London Ares. Dnt J Ir.duttr Med 22:261-2G9 (Oct) 1965. 14 Selikoff, IJ, at al: Aabaatoaia and Neoplasia. Amer J Med 43:487-496 (April) 1967. IST00 1590 00Ul 68?3