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/*',* * r" vt,. r.'-*.*.*v*rtT.-*.c* A;.* i- ' ,*i "C \ zl - C-:*v4 ly A?a '! *^r>J L C. PLAINTIFF'S EXHIBIT ASA-694 Asbestos Exposure, . Smoking, and Neoplasia H Iruing ]. ScUkaff, AfD;. E. Ciiyler Hammond, ScD; and Jacob Churg, MD Asbestos insulation workers, as a group, have a high risk of dying of bronchogenic carcinoma (3bout seven or eight times eipeciad). VYe have observed 370 such work men from Jsn 1, 1563 to April 30, 1557. Our findings .indicate that asbestos exposure alone is not the entire explanation. Of S7 noncigarette smokers, none died of bronchogenic carcinoma. Of 233 workmen with" a history of regular cigarette smoking, 24 died of bronchogenic carcinoma, although only three were- expected to die of this disease, talculations suggest that asbestos workers ' who smoke have about 92 times the risk of dying of bronchogenic carcinoma as men who neither work with asbestos nor smoke cigarettes. Vie conclude that asbestos exposure should fca minimized, that asbestos workers who do not smoke should never start, and that those now smoking should stop immediately. Tn 1984, we reported on deaths occurring between ? Jan 1, 1943, and Dec 31, 1962, among 632 members of the International Association of Heat and frost Insulators and Asbestos Worses.' All of these men had been occupationally exposed to asbestos dust for many ye.3rs. Their death rate from lung cancer was found to be 6.8 times as high as that reported for the general white male popu lation of the United States during the same years, with age taken into consideration. Three of the men' riied of diffuse pleural mesothelioma and one died of a neoplasm histologically suggestive of peri toneal mesothelioma. This was of interest since me.-othslioma is a very' rare disease in the general population but is reported to be associated with exposure to asbestos dust.' In addition, their death rate from cancer of the stomach, colon, and rectum was higher than expected; but this may have been crorr. the D'partrnsnt of Community Mc-dicine. Mount Sinai School of Medicine iOrs. S*Uko5 Churg), and the D*\orlrr.vnt of Kp.J,,-:r.;ohy and Sufiitirt. Americcn Cancer Society (Dr Hviminvnd}, Ne* York. Head before a joint meeting of the Section on Dis**nsvs of the Chest wjth thir Section un Preventive* Medicine and the American CoSie-e cf Chtst Physicians at tin* 21 nth annual conv*n:it.i of the V;ncric_an Medical A^ci^inri, Atlantis City, NJ. June ID. 1937. Reprint requests* to Mount Sinai School of Medicine, lOOlh Street and Fifth Avenue, New York 101/29 (Or. Selikofl). due to chance, the number of such deaths, being small. During the latter part of the study, we ob tained information on the smoking habits of. most of the survivors, but we could not obtain reliable information on the smoking habits of those who had died at an earlier date. Therefore, we could not at that time investigate death rates in rela tion to smoking habits and exposure to asbestos dust which were considered both separately and jointly. There is abundant evidence that cigarette smok ing leads to a high rate of death from lung cancer in the absence of occupational exposure to asbestos dust.'14 Our findings outlined above suggested (but did not prove) that exposure to asbestos dust may lead to a high rate of death from lung cancer in the absence of cigarette smoking. If the latter be so, then the combined effect of both types of ex posure might or might not be equal to or greater than the sum of the two effects. On the other hand, it wa3 possible that exposure to asbestos du0* in creases the risk of lung cancer among cigarette smokers but does not lead to lung cancer among nonsmokers. The present study was undertaken primarily to investigate these possibilities. In addition, we wished to obtain more information on the occur rence of mesothelioma and gastrointestinal cancer among asbestos workers. Material From records of New York Local 12 and Newark, NJ, Local 32 of the International Association of Heat and Frost Insulators and Asbestos Workers, a list was made of every man who was a member of either 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 of the men had first- been occupationally exposed to asbestos dust prior to 1922, and an additional - JAMA. April a. 1953 Vot 2C4. No 2 ASARCO ELP 0003221 A u-:e-su -.off er al 107 293 men had first been ex Table 1--Subjects Classified by A* as of Jin I. 1S63. and by Years From First Occupational posed- "between the be- C/posure to Asbtvtcs Oust up to Jan 1.19S3 -r.ning of <923 and the \d of 1942. All of these rnen-.-'were successfully traced through Dec 31, 11552, 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 first exposure to asbestos *{?' 35-39 40-44 45-49 $0-34 35-53 60-64 5*69 70.7* 75-79 80-84 Toil! ToUl No. of Subjects ' :* 22 .n 12 32 17 1C9 . , 50 42 49 33 * 21 4 ... 370 31 No. of Years Since First *>osur to A*Ve*tO* 25-29 ... 1 2 1 1 1 ... ... 30-34 ... .. 13 80 rs % i ... * ...... 35-39 .....- ... 28 34 11 10 ..3. ... 40-44 ... . .. ... 8 19 18 12 1 1 45-49 ... ... ... ... 1. 8 18 6 5 1 * 6 113 86 59 39 SO+ 2 17 25 2 36 _No. of 52 Uo ... i 2 18 11 16 >7 16 6 3 94 dust and 255 occurred after the 20th anniver Table 2.--Subjects Classified by Age and by Smoking Habits on or about Jan 1# 1963 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. AH of them have been traced, and- 94 of Ana. iff 35-39 40 44 45-59 50-54 55*59 60-64 65-69 70-7* 75-79 80-34 Total Total No. 2 13 32 109 60 42 49 38 21 4` 370 Smoked Regularly 1 2 2 12 6 7 .6 7 3 2 43 ClVir Only ... ... 1 6 5 4 8 7 7 l 39 cigarette Smokers* 1 2 S 26 16 15 17 12 6 1 10X Current Clc*ratt e Smokers* 1*9 .D..ay ...... .3.. 1 ... ..i.... 5 10*19 a ..O...a.y ... * 5 ..3. 4 4 1 17 20*39 a Oay- ... 5 12 * 33 20 11 94 3 in 97 40* ' Oay . *** 4 12 24 10 4 S 3 ..1. * 63 them were sound to have 'Includes cigarette smoker* who also smoked or cigars. died during the four-year and four-month interval from Jan 1, 1963, to April 101 were excigarette smokers, five currently smoked '*0. 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 ro 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.5 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 compl.h.-s. Altogether, *a. have general population sample; age was taken ir.ta examined "335 l9l.4) of th.e 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 ori smoking habits was obtained by tion, we examined hospital records, postmortem personal interview' with tbe 33S men who were ex findings (41 cases), as well as the surgical and amined. Of the 32 men w'ho were not examined, pathologic reports 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 well) 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 ail of example, in one instance the death certificate in the 37G 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 by 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 1967. 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 smoked or had smoked pipes or cigars but never from bronchogenic carcinoma to cancer of the smoked cigarettes regularly, and 2S3 had smelted stomach with metastasis, to the lungs while review a.-c-r:es regularly. Some of those with history of in another instance resulted in exactly the oposite ^.garette smoking also smoked pipes or cigars. Of change. The 94 deaths were ascribed to the follow the 253 with a history of regular cigarette smoking, ing causes: bronchogenic carcinoma, 24; pleural JAMA. A>nl 3. 1353 Vol 204, No 2 ASARCO ELP 0003222 :c-3 AS3SST05 EXPOSURE t=L!KOrr ET AL Tails 3.--OSservid in-i Ex?:-c.:zd Number of Csaths Among *' 370 Astsstos Workers Oaring t.*i2 52-?.:on:ti Period Cio* O/ Dt*U% JJtttI. oano.r (n ideal Car-ear of tuns, slaura. brenshy*. and trChea Sronchcsenie carcinoma P;-i.ra( mefcOthaficma Pii.'ainil mesothelioma Conor Of stomach Cancsr of colon and ctctom Carcor of ill othar tltis combined Asbestosis Hurt and circulatory dilute including strcVa All other eiutet of death Ob#.erv%d Deaths *9 27 24 3 7 3 S 7 15 22 8 Outfit* 36 23 t t t 06 1.2 4.$ 21.5 10.4 Total, at! c*vs*s S* 47.5 Batad toon US rrortal.ty <Sol dlwe.-i'dlnj imoXinx habit*. . TU.-ited Siatoa e.ta not avoilotla. bo; f'gure should be only slijiitly tess thsn 2.3. ; United Suits dot* not available. but thee. are rare causes of death in general 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; cornary 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; and accidental fail, one. Expected Deaths.--For purposes of comparison, we wished to ascertain how many of the 370 sub jects would have died during the 52-month period {Jan 1, 1983, to April 30, 19S7) if their age-specific death rates had been exactly the same as for the general white male population of the United States. For this purpose, we made use of the United States 19S-t life table for males; this prc"fled 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.*'' Or, 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 classified 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 370 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 are the same as for United States white males in general. The computation indicated that 47.5 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 causa of death among United States white males of various ages during the year 1984 as reported by the National Center for Health Sta tistics. These percentages were then standardized for 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 lung (including sarcoma of the lung), car.cer of the bronchus, cancer of the pleura, and cancer of the trachea. For this group of diseases, there were' 27 observed deaths and only 213 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 bron chogenic carcinoma. Thus, it may be assumed that there were close to 2.3 expected deaths from this causa as compared with 24 observed deaths, a ratio of over 10 to 1. Mesothelioma.--Ten 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 rar^cvn sample from the general population, one would not have expected any of them to die of mesothelioma within a period of 52 months. 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,1 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 those 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 S, I9E3 Vo! L'O-t. i.'o 2 ASARCO ELP 0003223 . . C i`~S7 CS ELXPC5' iff ET At 1C-3 that the-:- = subjects were primarily insulation work TabiJ 4.--Estimated Nerr.iir c< Lung Cancar Deaths Expected to Occur Ouria- a Period of 52 Months per 10.000 Man living at the Start of Period; by Age and by Srr.0V.in5 Habits* ers. While all of them were occupationally ex posed to asbestos dust, "tfieir decree of exposure was light as compared with the degree of ex posure of asbestos miners, processors, and weavers in earlier times. Bronchogenic Carci noma.--Bronchogenic car cinoma accounted for 24 deaths while only about 2.3 were expected on the . (JzAnc1*,. Yf 35*39 40*44 4S-<9 . 50-54 55-53 60-54 65-69 70-74 7650*-7949 RSefrirgt.ucteil.aerrtlfy 0 2 2 7 6 1146 12 . 23 25 COP7in?.l1y..t ...t CSimefcnkxerersttJe s. Current C!jr.:t9 Smaicnf a 1O*9xy a10O*1a9/ a20D.3a9y a4_0O4a*y ... 2 12 25 31 32 52 S3 32 1075 22 23 S3 71 80 97 ... 100 103 I1C4O8 ... ... ** *44 91 157 20$ 13$ * ... 3IS9 69 117 190 305 233431 4165 90 . 215865 sso* 450* . 329 ... upon data from a prc*.?F<tie stud/ with adjustment for US mortality experience, t Classes indicate rates omitted for ce'.cgonrs with no subjects in this study. See Table 2. ilnciudes cigarette amo'rers who also stocked pipe or cigar. Men with a history of only cigaratt* smoking have higher lung cancer rates than shown here. $Pates obtained by smoothing the data. 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 rnen. 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 carry 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 clone 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 4 40,000 men en in 1964 than during the period 1960 to 1964 as a rolled by American Cancer Society volunteers in whole. Furthermore, in ttye study described above, a prospective epidemiological study between Oc we avoided enrolling seriously ill people and, as of tober 1S5S and March 1980 and traced through the cut-off date for preparing the computer tape, Sepc 30,1964. Causes of death were ascertained from we had not yet received death certificates for 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 J.:-agresment bet'"--i the two source of infor aporeriably lower than those reported for 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 death 1960, and ending on Sept 30, 1964. The number of rate (disregarding smoking habits) in each five- lung cancer deaths occurring during the 52-month year age group would be the same as that of all period was divided by the number of men alive at United States white males (based upon the 1964 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 computations 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 for bined); (2) history of regular pipe or cigar smok further 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 shown in each of who had smoked or currently smoked pipes or the corresponding internal cells of Table 2. This cigars); and (4) current regular cigarette smokers yielded an estimate of the number of lung cancer (including those who also had smoked or currently deaths expected to occur during a 52-month period smoked pipes or cigars). The last of these cate among the 370 asbestos workers classified by their gories was further divided by current number of smoking habits. By "expected" number, we here 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 under the null 20 to 39 cigarettes a day; and (4d) 40 or more hypothesis that asbestos workers do not differ from cigarettes a day. Since the men were divided into other men in respect to their lung cancer death seven groups by smoking habits and further sub rates, both age and smoking habits being taken JAMA. April 8. 1S53 Vol 204. No 2 ASARCO ELP 0003224 j'io -. ASBESTCS EXrCSU.-.i-SELIKOrE ET M Til!* 5.--Otij-ir.trd and Expected Gronchoranie Carcinoma Daaths by S.-neVi-j Habits* for 370 Asbastos Workers Smofctnx Habit* ttevar sm'sVed reguUrty `History of pip*, c:r smoking only History of regular cigarette smoklngt Total Observed 0*Clb* 0 0 24 u pasted Deaths COS 0.13 2.S8 Tie "S.s.9 upon d>u in Ta!>!. 2 nd *. f lnctuCo cigarette imoun who alo amoved ptpe or cigar. Table 6.--Expected and Observed Ceatfis Among 632 Asbes-' tos Workers Exposed to Asbesto Dust 20 years or Longer ELcpvcted Observd Total cnort ell site* pnc!%d Observed Cancer of Iyn* trachea, pleura ap*ct<rd^ Observed Cancer cf stomach. colon, rectum Etp-*ct*d Observed Cancer all other cits* combined ptp*i:ted Observed Asbestos^* xp*Cted Observed All other cause* cipected Observed 1S434962 2C3.S zss Total 1552-1957 IS4M9S7 47.5 94 2SI 549 3o.S 95 3.6 49 45.1 :u 6.6 S 2.3 27 8.9 72 9.4 29 1.8 21,2 8 37 20.5 21 *.s 14 25 35 000 !2 IS 27 _ ___ 157 33.9 2053 143 30 173 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 ;:.r of the excess '-.onchogenic care:-' na deaths might be attributed to the fact that there appear to l ave 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 of 6.8 to 1 (not taking smoking habit3 into considera tion). It should he noted in this connection that the 370 subjects in this study had been exposed to asbestos dust somewhat longer than the subjects of our previous study (the present 370 subjects are survivors as of Jan 1, 1953, of subjects in the previous study). Oi the subjects who never smoked regularly and those who smoked only pipes or cigars, none died of bronchogenic carcinoma whereas 0.1S of these men wore expected to die of lung cancer. Th:3 sug gests that exposure to asbestos dust does not in crease toe risk of bronchogenic carcinoma among men who never smoked cigarettes regularly. How ever, considering the small 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 man with a history of regular cigarette smoking died of bronchogenic carcinoma whereas only 2.9S 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 (te, 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 does 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 r.rsd expected number of deaths for each of two periods (the first, 1943 to 1932, being previously reported') 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 Endings in the two periods are in close agreement. Comment The increased risk of neoplasia (mainly broncho genic carcinoma arid 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 5% to 15%. Conditions of work vary; these men often work outdoors unlike asbestos operators in factory work. Comparatively few dustexposure surveys have been made in this trada but their results have generally been within the 5 mil lion particles per cubic foot permissible limits cur rently accepted by the American Conference of Governmental Industrial Hygienists.*-10 Nor have JAMA. April 8. lGc-2 Vs! 2C i. No 2 ASARCO ELP 0003225 ASSES70$ EXPOSURE--?SL;.<C?r Er AL i 111 additional potentially carcinogenic substances Leon identified among the other materials used.10 " Keener or even lighter exposure may result in different degrees of risk of neoplasia. Heavy factory exposure in the past has in some instances resulted -in considerable lung cancer risk.'* In others, para doxically, little lung cancer was seen because r.sb&stcsis was so common and so severs as to causa death of the exposed workers before they could live long enough to develop lung cancer. Once exposure was reduced by improved industrial hygiene prac tices, early death from asbestosis sharply dimin ished and lung cancer became common.*' In any case, heavy exposure is not likely to be the most important problem in the future, unless there be sheer carelessness or unconcern. Rather, light exposure, similar to that in insulation work, will he much more common, both in 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 affect 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 mesothelioma.** What is not now 1. -;c\vn 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 cocarcir.ogenic 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 riser, to over 4,000,000 tons per year now), it may be difficult for cigarette smokers to avoid inhaling air contaminated with asbestos. It 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 neously; there was much less asbestos used 20 to 40 years ago. Youngsters who start smoking now have a much greater chance of having both ex posures simultaneously. Significance of Findings for Asbestos Workers.-- The import of the data reported here seems clear. Thc-re is an extraordinary risk of developing and * dying from lung cancer for. asbestos 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 283 asbestos workers who had a history of cigarette smoking, 78 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 7S 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, only 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 0.28 would have been expected to die of tha 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 three died of asbestosis and one died of peritoneal mesothelioma). This finding, being based upon the experience of only S7 men, does 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 doss 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 as 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 iheir tissues for the remainder of their lives. 2. AH 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 that 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. This invisitsMton supported by th< Health Research Coun cil of lha City of Nf-v York, ft&fsrenc^s 1. Selifeaff, I.J.: ChuifT. J.; and Hammond, EC.: Aj-hotos Ex posure ar.c JAMA J5S:2-26 (April C> l'JtM, 2. SeUko.X I.J.; Chury. J.: nod Hammond, E.C.: Relation He- I'vaen Exposure to Asbolcs and Mc-jxitheHorr.a, Neiu Enj J Afd 272:5c0-S5J (March IS) !9So. JAMA. April 8. IS68 Vo'. 204. No 2 ASARCO ELP 0003226 11? AS3EST0S EXPOSURE--SEUKCFF ET AL 3. Kiraxtuni. E.C.: "Smoklr.? ia to ifce Qvs'si P-- ot l.fXO.COO Mna nrA SVao.*" In Epidrmiatsxint Si`-dy ot Conor jcud Other Chronic DUecjct, ?*ldi Kaiion.il C>aoif Institute, 1956. tnccofraph 19, pp 127-004. 4. Smckinj end Health, Report of the Advfcory Ovc-.niUte-* to (he Surjwi General of the Public K**Kh Service. publication 1X03, US Dept of Health, Education, end Welfare. 1964. 5. Hammond, E.C, and GarSnfcel, L.: Chengs* in GprttU Smoking 1959*1955. Amer J Public Health 3;20-tf (Jan) 1963. 6. Vitef Statistics of /Ae Untied Sides, I960, part A, US Dept of Health, Education, end Welfare, 1S63, vol 2. 7. Death Rates From Malignant Kfoplzsms, 2d0, Public Health Service, publication 1113. US Dept of Health* Education, and Welfare, 1963. 9. Mortality by Occupation and Cause of Death, Public }U jtl(h Service, US Dept of Health, Education, and Welfare, Vital Sta tistic* Division. Vital S'-ati*tco-Sp-2?ciat Reports, 3:323 (Spt) 11X3. 9. Fleeter, W.E., cd al: A Kcnlth Survey of Pip*-Covertr*j Op-iretiona sa Ctaatructinj Naval Vessels, J Induszr Hyz Toxic 23:9-16 (Jan) 1946. 10. Keane, W.i.. end Zavon, M.R.: Occupational Hazards of Pipe Insula tern, Arch Environ Health 13:171-173 (Au*> I960. 11. Doll, fL: Mortality From lAir.g Cancer ia Asbestos Workers, Brit J tndusir Med 12:31-56 (April) 1955. 12. Jacob. G., and Anspach, M: Pulmonary Neoplasia Arooo* Dresden Asbestos Workers, Ann NY Acad Sc 132:536-543 (Dec 31) 1955. 13. Mewhouse. M.L,. sod Thotnpeou. HL: Mosotheliocsa of Pleura aod Peritoneum Following Exposure to Asbestoa in the London Area, Eat J Industr Med 22:2Sl-2$9 (Oct) 1965. 14. $*lik<xt I,,T., et al: Asb-cstoais cod Neoplasia, AtrterJ Med 42:437-436 (April) 1967. ASARCO ELP 0003227