Document G66mxyXw9g9kJ4evVvq34D7eY

j06 Asbestos Exposure, Smoking, and Neoplasia In'ing ]. Solihull, MD; . Cuyler Hammond, ScD: and Jacob Churg, MD Asbestos insulation workers, as a group, have a high due to chance, the number of such deaths being risk of dying of bronchogenic carcinoma (about seven or small. During the latter part of the study, we ob eight times expected). We have observed 370 such work tained information on the smoking habits of most men from Jan 1, 1963 to April 30, 1967. Our findings of the survivors, but we could not obtain reliable indicate 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 bronchogenic 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 asbestos carcinoma, although only three were expected to die of dust which were considered both separately and this disease. Calculations suggest that asbestos workers jointly. who 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 exposure should be minimized, that asbestos workers who dust.*' Our findings outlined above suggested (but do not smoke should 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 cancer in the absence of cigarette smoking. If the latter be n 1964, we reported on deaths occurring between so, then the combined effect of both types of ex I Jan 1, 1943, and Dec 31, 1962, among 632 posure might or might not be equal to or greater members of the International Association of Heat than the sum of the two effects. On the other hand, and Frost Insulators and Asbestos Workers.* All it was possible that exposure to asbestos dust in of 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 be 6.8 times as high nonsmokers. ' as that reported for 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 died of diffuse pleural mesothelioma and one rence of mesothelioma and gastrointestinal cancer died of 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 of rate from cancer ol the stomach, colon, and rectum Heat and Frost Insulators and Asbestos Workers, was higher than expected; but this may have been a list was made of every man who was a member From (he Department ol Community Medicine. Mount Sinai School of Medicine iDrs. SelikoH onH Churg), and Ihe Depart of either one of these locals on Dec 31, 1942, or who joined between that date and Dec 31, 1962. ment of Epidemiology and Statistics. American Cancer Societv (Dr. Hammond). New York. ` Read before a joint meeting of Ihe Section on Diseases of Ihe Chest with the Section on Preventive Medicine and the American College of Chest Physicians at the 116lh annual convention of Ihe American Medical Association. Atlantic City. NJ, June 19. 1967. Reprint requests to Mount Sinai School of Medicine. 100th Street and Filth Avenue. New York 10029 (Dr. Selikofl). 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 dutft prior to 1922, and an- additional 104 P: AMA, April 8. 1968 Vol 204. No 2 FOS 0009337 SCF-FA-6090 I ASBESTOS EXPOSURE-SELIKOFF ET AL 107 293 men had first been ex posed between the be Table 1.--Subjects Classified by Age as of Jan 1. 1963. and by Years From First Occupational Exposure to Asbestos Dust up to Jan 1. 1963 ginning of 1923 and the end of 1942. 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 Age, Yr 35-39 4044 45-49 50-54 55-59 60-64 65-69 70-74 75-79 BO-84 Total f4o. of Subfects ' 20-24 22 13 12 32 17 109 60 42 49 38 21 4 No. of Years Since First Exposure to Asbestos 25*29 1 2 30-34 .. 13 80 16 3 1 ... 35*39 .. 28 34 11 10 3 .. 40-44 .. 8 19 18 12 1 1 45-49 ... ... Hi 8 18 6 5 1 SO+ ... . .r . r- 2 17 15 2 _No. of 52 Mo l 2 18 11 16 17 18 8 3 first exposure to asbestos Total 370 31 6 113 86 59 39 36 94 dust and 255 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.--Subjects Classified by Age and by Smoking Habits on or about Jan 1, 1963 Age, Yr 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 Tout No. 2 13 32 109 60 42 49 38 21 4 Never Smoked Regularly 1 2 2 12 6 7 6 7 3 2 Pipe, Cigar Only ... 1 6 5 4 8 7 7 1 cigarette Smokers* 1 2 5 26 16 15 17 12 6 1 Current Cigarette Smokers* 1*9 Day 10-19 a Day 20*39 a Oay 40+ ' a Day 54 12 12 3 5 33 24 3 20 10 1 11 4 49 S 1 44 3 ... 1 3 1 ... been traced, and 94 of Total 370 48 39 101 5 17 97 63 them were found to have Includes cigarette smokers who also smoked pipes or cigars. died during the four-year 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 (91.4) 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 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 all of the 370 men. Table 2 shows their smoking habits example, in one instance the death certificate in 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 1967. lioma; but in another instance exactly the reverse 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 283 had smoked cigarettes regularly. Some of those with history of stomach with metastasis to the lungs while review in another instance resulted in exactly the oposite cigarette smoking also smoked pipes or cigars. Of the 283 with a history of regular cigarette smoking, change. The 9^ deaths were ascribed to the follow ing causes: bronchogenic carcinoma, "24; pleural JAMA, April 8. 1968 Vol 204. No 2 P . . ' 105 FOS 0009339 108 ASBESTOS EXPOSURE-SELIKOFF ET AL Table 3.--Observed and Expected Number of Deaths Among 370 Asbestos Workers During the 52-Month Period Cause of Death Total, cancer (all sites) Cancer of lung, pleura, bronchus, and trachea Bronchogenic carcinoma Pleural mesothelioma Peritoneal mesothelioma Cancer of stomach Cancer of colon and rectum Cancer of all other sites combined Asbestosis Heart and circulatory disease including Stroke All other causes of death Total, all causes Observed Deaths 49 27 24 3 7 3 5 7 25 22 8 94 Expected Deaths* 8-6 2.3 t * 0.6 1.2 4.5 28.5 10.4 47.5 'Based upon US mortality data disregarding smoking habits. tUnited States data not available, but figure should be only slightly less than 2.3. .. tUnited States data not available, but these 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 fall, 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, 1963, to April 30, 1967) 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 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.'T 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 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 cause of death among United States white males of various ages during the year 1964 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 us Observed Deaths.--As shown in Table 3, there were 94 observed deaths (ie, 94 of the 370 asbestos workers died) 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 t.ie lung), cancer of the bronchus, cancer of the pleura, and cancer of the trachea. For this group of diseases, 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 bron 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. 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 random 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,' 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 106 P: AMA, April 8, 1968 Vol 204, No 2 FOS 000934-0 ASBESTOS EXPOSURE--SELIKOFF ET AL 109 that these subjects were primarily insulation work Table 4.--Estimated Number of Lung Cancer Deaths Expected to Occur During a Period of 52 Months per 10,000 Men Living at the Start of Period; by Age and by Smoking Habits* 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 Age, Yr <Jn 1. 1963) 25*39 40-44 45-49 50*54 55-59 6064 65*69 Never Smoked Regularly 0 2 2 7 6 16 14 Ripe, Cigar Only ...t 2 12 15 31 32 Excigarette Smokers^ 5 75 10 22 53 71 97 1-9 a Day ... ... ... 28 .8.0. Current Cigarette 'Smofcerst 1019 a Day ... ... 44 ~ 91 ... ` 157 20-39 a Day ... 15 39 69 117 190 305 . 40+ a Day . .. 15 46 90 185 256 350* in earlier times. Bronchogenic Carci noma.--Bronchogenic car cinoma accounted for 24 deaths while only about 2.3 were expected on the 7074 75-79 8084 12 28 25 52 100 103 206 288 450* S3 100 185 341 329 32 148 ... 'Based upon data from a prospective study with adjustment for US mortality experience, t CUipses indicate rates omitted for categories with no subjects in this study. See Table 2. (Includes cigarette smokers who also smoked pipe or cigar. Men with a history of only cigarette smoking have higher lung cancer rates than snown here. Rates 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 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 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 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 of tober 1959 and March 1960 and traced through the cut-off date for preparing the computer tape, Sept 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 disagreement between the two sources of infor appreciably lower than those reported for white mation, the physician's statement was accepted. For the purpose at hand, we only made use of data covering the 52-month period beginning on June 1, 1960, and ending on Sept 30, 1964. The number of males in the United States in 1964. To compensate for this, we raised the rate of each individual smok ing category so that the total lung cancer death rate (disregarding smoking habits) in each five- lung cancer deaths occurring during the 52-month period was divided by the number of men alive at the beginning of the period. This was done by fiveyear age groups for men in each of the following smoking categories: (1) never smoked regularly (nonsmokers and occasional smokers being com 'year age group would be the same as that of all United States white males (based upon the 1964 life table and the 1964 distribution of deaths by causes of death). The results of these computations are shown in Table 4. (It should be noted that 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 regularly; (3) excigarette smokers (including those The rates shown in Table 4 were then applied to the number of asbestos workers shown in each of who had smoked or currently smoked pipes or cigars); and (4) current regular cigarette smokers (including those who also had smoked or currently smoked pipes or cigars). The last of these cate gories was further divided by current number of cigarettes smoked per day: (4a) one to nine ciga rettes a day; (4b) 10 to 19 cigarettes a day; (4c) 20 to 39 cigarettes a day; and (4d) 40 or more cigarettes a day. Since the men were divided into seven groups by smoking habits and further sub the corresponding internal cells of Table 2. This yielded an estimate of the number of lung cancer deaths expected to occur during a 52-month period among the 370 asbestos workers classified by their smoking habits. By "expected" number, we here mean an estimate of the number of lung cancer deaths which would have occurred under the null hypothesis that asbestos workers do not differ from other men in respect to their lung cancer death rates, both age and smoking habits being taken P . ' JAMA. April 8, 1968 Vol 204, No 2 107 FOS 0009342 110 ASBESTOS EXPOSURE-SELIKOFF ET AL Table 5.--Observed and Expected Bronchogenic Carcinoma Deaths by Smoking Habits* for 370 Asbestos Workers Smoking Habits Never smoked regularly History of pipe, cigar smoking only History of regular cigarette smokingt Observed Deaths 0 0 24 Expected Deaths 0.05 0.13 2.98 Total 24 3.16 "Based upon data in Table 2 and Table 4. tlncludes cigarette smokers who also smoked pipe or cigar. Table 6.--Expected and Observed Deaths Among 632 Asbes tos Workers Exposed to Asbesto Dust 20 years or Longer Total deaths: all causes Expected Observed Total cancer all sites Expected Observed Cancer of lung, trachea, pleura Expected Observed Cancer of stomach, colon, rectum Expected Observed Cancer all other sites combined Expected Observed Asbestosis Expected Observed AM other causes Expected Observed 1943-1962 203.5 255 Total 1963-1967 1943-1967 47.5 94 251 349 36.5 95 8.6 49 45.1 144 6.6 45 2.3 27 8.9 72 9.4 29 1-8 11.2 8 37 20.5 22 4.5 14 25 35 00 12 15 0 27 167 38.9 205.9 148 30 178 into consideration. The results are summarized in ~ ble 5 which shows the expected and observed jiber 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 of 6.8 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 of 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 bronchogenic carcinoma whereas 0.18 of these -n were expected to die of lung cancer. This sug gests that exposure to asbestos dust does not in crease the 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 men with a history of regular cigarette smoking died of bronchogenic carcinoma whereas only 2.98 were expected to diffDf it, a ratio of 8.05 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 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 and expected number of deaths for each of two periods (the first, 1943 to 1962, 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 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 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 trade 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 108 P JAMA. April 8. 1958 Vol 204. No 2 FOS 000934-1 I ASBESTOS EXPOSURE-SELIKOFF ET AL 111 additional potentially carcinogenic substances been identified among the other materials used.' Heavier 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 asbestosis was so common and so severe as to cause 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 be 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 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 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. There 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 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, 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 0.26 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 three died of asbestosis and one died of peritoneal mesothelioma). This finding, being based upon the experience of only 87 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 does not lead to an ex tremely high risk of lung cancer among nonsmokeis. 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 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 that the decrease in risk which results from cessation of smoking among the general public3 will be the good fortune of the asbestos workers as well. This investigation was supported by the Health Research CouOt dl of the City of New York. References 1. SelikofT, I.J.; Churg, J.; and Hammond. E.C.: Asbestos Ex posure and Neoplasia. JAMA 188:22-26 (April 6) 1964. 2. SelikoS. I.J.; Churg, J.; and Hammond. E.C.: Relation Be tween Exposure to Asbestos and Mesothelioma. New Eng J Med 272:560-565 (March 18) 1965. ; JAMA. April 8. 1968 Vol 204. No 2 P *9 FOS 0009343 ; 1X2 ASBESTOS EXPOSURE--SEUKOFF ET AL 3. Hammond. E.C: "Smoking in Relation to the Death Rates of 1.000,000 Men and Women," in Epidemiological Study of Cancer and Other Chronic Diseases, Bethesda. Md: National Cancer Institute, 1966, monograph 19. pp 127-204. 4. Smoking and Health. Report of the Advisory Committee to the Surgeon General of the Public Health Service, publication 1103, US Dept of Health. Education, and Welfare. 1964. 5. Hammond, E.C, and Garfinkel, L.: Changes in Cigarette Smoking 1959-1965. Amer J Public Health 58:30-45 (Jan) 1968. 6. Vital Statistics of the United States. 1960. part A. US Dept of Health. Education, and Welfare, 1963. vol 2. 7. Death Rates From Malignant Neoplasms. 1960. Public Health Service, publication 1113. US Dept of Health, Education, and Welfare, 1963. 8. Mortality by Occupation and Cause of Death. Public Health Service. US Dept of Health, Education, and Welfare. Vital Sta tistics Division, Vital Statistics-Special Reports, 53:323 (Sept) 1963. 9. Fleischer, W, et al: A Health Survey of Pipe-Covering Operations in Constructing Naval Vessels, J Industr Hyg Toxic 28:9-16 (Jan) 1946. 10. Keane, W.T., and. Zavon. M.R.: Occupational Hazards of Pipe Insulators, Arch Environ Health 13:171-178 (Aug) 1966. 11. Doll. R.r Mortality From Lung Cancer in Asbestos Workers, Brit J Industr Med 12:81-86 (April) 1955. 12. Jacob, G. and Anspech. M.: Pulmonary Neoplasia Among Dresden Asbestos Workers, Ann NY Acad Sc 132:536-548 (Dec 31) 1965. 13. Newhouse, M.L. and Thompson. H.: Mesothelioma of Pleura and Peritoneum Following Exposure to Asbestos in the London Area. Brit J Industr Med 22:261-269 (Oct) 1965. 14. SelikoS, IJ.. et al: Asbestosis and Neoplasia. Amer J Med 42:487-496 (April) 1967. Many, possibly most, of the words in the dictionary stand there as representatives of a whole family of forms. Not even the timidest of the linguistically timid will run to the dictionary for encouragement when, for instance, they want to refer to a spell of "hiccuping," provided they are certain that Webster does know "to hiccup." All the tense forms, the participles, the gerunds are assumed to be authorized by implication the moment the infinitive is known to exist. The plurals of nouns are similarly taken for granted, and the forms of comparison and the adverbial forms of adjectives. This phenomenon is generally covered by the assertion that a dictionary is not a grammar and that each individual entry in a dictionary stands simultaneously for all its grammatically possible forms. (For details, consult your grammar.) But is a gerund a grammatical form? Or is it a suffix-derived noun? I am not really looking for an answer. I ask those questions to suggest that the dividing line between grammatical form and derived neologism is both hard to de fine and artificial. If I distinguish--among men--the "hunting" from the "hunted," I have done no more than form (grammatically) two nouns from two adjectives which are forms (grammatically) implied in the existence of "to hunt." But if "hunting" is implied, why not "hunter"? Why not "huntee" and "huntable" and "huntabilize"? The question of when a new word is a new word and when it is merely an "im plied" form of a conventional term is indeed more complex than is grossly ap parent. Take "dehairability" as an example. Can I claim the word is implied in the existence of "hair," or must I assume the responsibility for having spawned a monster? Or take "unequivocably," which indeed was the starting point of all this rea soning and wondering, for it was spotted as a bold neologism in JAMA in the sentence, "Research at the Public Health Service Hospital at Lexington, Ky, has unequivocably proven that methadone has all of the euphoric properties of morphine. ..." Now, clearly, the adverb "unequivocably" is grammatically implied in the ad jective "unequivocable," and this in turn is implied--grammatically of semi-gram- matically or otherwise--in "equivocable." If we grant further that formations in "-able" of "-ible" are likewise legitimate without special dispensation, we shall conclude that "unequivocably" is in no sense a bold departure since "to equivo cate" is a firmly established, standard English word. But there is a hitch and a flaw in the argument. "To equivocate" means "to use ambiguous language" and (by extension) "to render ambiguous." Hence, "equivocable" can only suggest the trait of "being apt or able to be made ambig uous," and that, I fear, was not intended. Which means, by (nongrammatical.) implication, that the discrepancy between the obviously intended meaning of "un equivocably" and its structurally supported significance was the cause of the un pleasant jolt experienced by the spotting reader. . PS.--It is of course possible, and even likely, that "unequivocably" was just a typo for "equivocally." . Alexander Gode, PhD 110 p JAMA, April 8. 1968 Vol 204, No 2 FOS 0009344