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177 Mortality Experience in a Group of Asbestos Workers Murri* Kleinfeid. MD: Jacqueline Mcs*ite. HD: and Olive Kooyman, MD. New York The TERM "asbestos" is used to identify a group of fibrous silicates. Prolonged inha lation of significant amounts of asbestos dust over an extended period of time can produce in certain individuals a respiratory disorder known as asbestosis. It is character ized primarily by cough, dyspnea, basal crepitations, and reticulonodular shadowing of chest roentgenograms. Clubbing and cy anosis are usually seen in the more ad vanced stage of this disorder. Chronic bron chitis and emphysema are associated with this disease, the emphysema being more of a localized than a diffuse obstructive type. Cor pulmonale is the major complication and usual cause of death from this disease. This is particularly true in those with excessive dust exposure. There is an increased inci dence of lung carcinoma and mesothelioma of pleura and peritoneum associated with sustained asbestos exposure. The most con sistent pathological finding is a dense fibro sis containing macrophages with absorbed dust particles which in many areas obliter ates the pulmonary architecture. A pattern of endarteritis with intimal hyperplasia consis tent with pulmonary hypertension and bronchiolectasia are associated major .findings. Rather striking is the presence of elongated, terminally clubbed bodies, both segmented and unsegmented, in the respiratory bron chioles or imbedded in the fibrous tissues or both. The pleura often shows dense fibrotic thickening, and not infrequently there are Submitted {or publication March 23. 1967; accept ed April IX From the Division of Industrial Hygiene. Mew York and the New York University Medical Ten ter. New York (Drs. Kleinfeid and Mcssitc). Reprint requests to Division of Industrial Hy giene, State of New York Department of Labor, SO Centre St. New York 10013 (Dr. Kleinfeid). calcified pleural plaques over the pleural surfaces. The clinical and patholgical fea tures are indicative of a pronounced dys function of the respiratiory mechanism. This has been confirmed by studies of pul monary function which have shown a dis turbance in both ventilatory function and diffusion capacity. The main physiologic al teration is a reduced diffusion capacity.1-3 The purpose of the present study was to obtain mortality data in a group of asbestos workers and to compare the observed mor tality experience from specific diseases with the expected mortality among a similar bas ic population. Material and Methods The study group consisted of 152 asbestos workers who had 15 or more years of asbestos exposure by 1945 or had achieved 15 years of exposure to asbestos dust between 1945 and 1965. Source of Data.--Personal data were ob tained from union records, and the occupa tional history obtained for each man included operations performed and dates and places of employment For those who had died, records of the health and wrifarc fund provided date and place of death. Copies of death certificates were examined in ail instances when available. The records of the physicians attending the workers privately were reviewed. Hospital records and histological specimens were examined whenever available. Autopsy records were obtained in 17 of the 46 deaths. Statistical Analysis.--Total number of deaths were distributed in the following categories: malignancies, cardiac, pneumoconiosis or com plications or both, accidents, and all other causes. The observed mortality from cancer of the lung and pleura and of the gastrointes tinal tract and peritoneum were compared with Arch Environ Health--Vol IS, Aug 1967 CHEV BB 178 MORTALITY EXPERIENCE--KLEINFELD ET AL Tabic 1.--Causes of Death in 4$ Asbestos Workers From 1945 to T965 Causa of Dtatn Number % -Malignancies lung and pleura Gastrointestinal and peritonaum All other malignancies Cardiac deaths (other than cor pulmonale) Asbestosis and complications Accidents AU other causes Total 23 SO 12 26.1 7 15.2 A 8.7 13 28.3 2 4.3 2 4.3 6 13.1 46 100 the expected mortalities due to the above causes in the various age groups. The expected mortality represents the proportion of deaths among US white males due to the specific causes in the year 1948. This particular year was chosen as standard because it is the medi an year of death' among the 46 deaths. The differences between the observed and the ex pected frequencies were detailed for signifi cance, using the normal curve for large numbers and the Fisher's exact probability test for small frequencies. Findings Total Deaths.--There were 46 deaths in the group of 152 asbestos insulators. The causes of death in the various categories are shown in Table 1. A distribution of the deaths according to age group showed that there was 1 less than 40 years, 21 between 40 and 59 years, 23 between 60 and 79 years, and 1 over SO years (Table 2). The average age of death of the 46 asbestos workers was 60.3 years with a range of 33 to 81. The av erage age for the overall group of 152 asbes tos workers was 53.7 years with a range of 33 to 81. Malignancies.--Of the 46 deaths, the ob served and expected number of deaths due to cancer of the lung and pleura, gastroin testinal tract and peritoneum are shown in Table 2. Of the 12 malignancies of the lung and pleura, ten were carcinomas of the lung, and two were pleural tumors, one a mesothe lioma and the other a fibrosarcoma. Of the seven malignancies of the gastrointestinal tract and peritoneum, two were cancers of the stomach; one, a lymphosarcoma of the small intestine; one, a cancer of the colon; and three were peritoneal tumors, two of which were mesotheliomas and one a mesentrie sarcoma. The malignancies involving other sites included one case of chronic lym phatic leukemia, and one retroperitoneal re ticulum cell sarcoma and one metastatic car cinoma. primary site unknown. Cardiac Deaths.--Of the 13 cardiac deaths excluding cor pulmonale, eight had coronary artery disease, three had hyperten sive heart disease, one rheumatic heart dis ease and one syphilitic heart Asbestosis or Complications or Both.--Of the 46 deaths, two had asbestosis complicat ed by cor pulmonale. All Other Causes.--Of the six in this cate gory, there was one each of the following: cerebrovascular accident, pulmonary tuber culosis, acute peritonitis, chronic arthritis, gangrenous appendicitis with peritonitis, and Laennec cirrhosis. Environmental Exposure.--The mean du ration of exposure for the 152 asbestos work ers was 26 years with a range of 15 to 56 years, while that for the 46 death cases was 31.8 years with a range of 15 to 47 years. Al though fiberglass was introduced into the industry during the past ten years, it is fair ly certain that all of these asbestos insula- Table 2.--Deaths and Proportional Mortality From Cancer ol the Lung and Pleura and Gastrointestinal Tract and Peritoneum Related to Age in Asbastos Workers Age Group 40 40-59 Total Oeaths 1 21 Deaths From Malignant Causes lung & Pleura 1 5 Grand Peritoneum 0 4 Proportional Mortality lung i Pleura Gl and Peritoneum Obsarved 1 23.8 Expected 7.4t Observed 0 19 Expected 5.6t 60.79 23 6 3 26.1 3.8t 13 5t 804- 1 0 0 0 0 Total 46 12 7 26.1 3.It 15.2 3.9t r Gl indicates gastrointestinal tract. t Oitlerence between observer! and expected valuer is statistically significant (P <"0.01). Arch Environ Health--Vol 15, Aug 1967 MORTALITY EXPERIENCE--KLEINFELI) ET AL 179 tors had a minimum at five years' exposure to asbestos dust. Even though fiberglass eventually became the primary component of the insulating material, some asbestos was nevertheless incorporated. Comments Malignancies--The data on carcinoma of the lung and pleura show an overall mortals ty from carcinoma of the lung and pleura to be approximately nine times that expected. Selikoff et al,3 who studied a similar group of asbestos insulators, found that the death rate from cancer of the lung and pleura was approximately seven times as high among the asbestos group as in the US white male population. As shown in Table 2, the in crease is significant both in the 40- to 59- and 60- to 79-year age groups. This is at variance with what was observed among talc workers exposed to mixed silicate dusts where die significant increase in cancer of the lung and pleura occurred in the 60- to 79-year age group rather than in the 40- to 59-year age group.4 The talc group consist ed of 220 talc millers or miners or both who had 15 or more years of exposure in 1940 or achieved 15 years between the period of 1940 and 1965. The overall mortality in the talc workers was 41.4%. The reason for an increased incidence of lung or pleural can cers in the younger age group among the as bestos workers as compared to the talc workers may be partly due to the greater carcinogenicity or longer duration of expo sure to asbestos or both. The asbestos work ers with lung or pleural cancers were ex posed on the average for 28.2 years, while the talc workers had an average exposure of 23.3 years. In addition, it is possible that other components such as the metallic ra tions present in the asbestos dust may also account for the difference in incidence of lung or pleural cancers between the two groups. In view of the meager history avail able on smoking, one cannot assess the role played by this factor in the causation of pul monary carcinomas among either the bile or asbestos workers. In four of the 12 asbestos workers where a smoking history was obtain able. one smoked two packs per day for 29 years; one, one pack a day for 24 years; one, half a pack a day toe over 20 years; and one smoked only two cigars per day for IS years. With regard to carcinoma of the gastroin testinal tract and puritonoum among the asbestos workers, a significant difference was found between the observed and expected frequencies in the overall and specific age groups studied. The present findings among the asbestos workers arc similar to those re ported by Selikoff et aL3 No significant differences was found between the observed and expected frequencies in the overall and specific age groups among the talc wokers. If a clear-cut etiological relationship is subse quently established between exposure to as bestos dust and carcinoma of the gastroin testinal tract, then one may attribute the difference in incidence between' the asbestos and talc groups to the reasons given for car cinoma of the lung and pleura. Deaths Due to Asbestosis and Complica tions.--Previous studies have reported that cor pulmonale is a major complication of as bestosis and a major cause of death among asbestos workers.* The findings in this study, however, are not consistent with the previous reports, and this may be explained by a lower concentration of asbestos dust exposure over a prolonged period of time. The mean duration of exposure of those who developed lung or pleural cancer was 2S.2 years with a range of 15 to 40 years. This is consistent with the observation of Gilson11 who recently pointed out that a reduction in asbestos dust exposure is less likely to pro duce chronic lung disease, but the risk of neoplasia increases with sustained exposure to relatively lower concentrations. In 26 of the deaths where roentgenographic data were available, 12 showed changes consistent with asbestosis. In only two of the 12. death was related to the asbestosis, cor pulmonale being the primary cause in both. Of the 12 that died of malignancy of the lung or pleura, five had asbestosis, and three did not, and no information was available on the remaining four. Correlation of Carcinoma of Lung or Pleura With Age, Duration of Exposure, or Asbestosis.--The mean age of the group of 12 workers who developed carcinoma of the lung or pleura was 56.5 years with a range of 33 to 71 years. This is slightly below the mean age of 60.3 years with a range of 33 to 81 years for the overall group of 46 death Arch Environ Health--Vol lJ, Aug 1967 CHEV BB 0003198 180 UORTAUTY EXPERIENCE--KLE1NFELD ET AL cases. The mean duration of exposure of those that had cancer of the lung and pleura was 28.2 years with a range of 15 to 40 years. The average years from onset of ex posureJo death in this group was 29.5 years with a range of 15 to 40 years. The mean du ration of exposure for the overall group of 46 deaths was 31.8 years with a range of 15 to 47 years. The differences in mean age and mean duration of exposure for the 46 deaths cases and the group that developed cancer of the lung or pleura are not statistically sig nificant With regard to cardnoma of the lung and asbestosis, the data indicated that five of the 12 individuals with carcinoma of the lung had asbestosis, three did not, and in four no information was available. The small number of cases plus the absence of information in four cases precludes the mak ing of any correlation. 1 Summary and Conclusions Mortality data on 46 asbestos insulators in New York state who has 15 or more years of exposure to asbestos dust by 1945 or had achieved 15 years of exposure between 1945 and 1965 were reviewed. The average age at death was 60.3 years with a range of 33 to 81 years. There were 12 deaths due to malig nancies of lung or pleura. The differences in the mean age and mean duration of expo sure for the 46 deaths and the group that developed cancers of lung or pleura were not statistically significant. Proportional mortality from carcinoma of the lung and pleura among asbestos workers studied was nine times that expected in US white moles. The observed mortality was significantly higher in the 40- to 59- os well as in the 60- to 79-year age groups. This was at variance with authors' previous findings among talc workers who had a similar dura tion of exposure covering a similar period but where the observed incidence increased significantly only in the 60- to 79-year age category. The occurrence of malignancy of lung and pleura in the younger age group of asbestos workers may be attributed to the greater carcinogenicity of asbestos or the longer duration of exposure to asbestos dust or both as compared to talc dust exposure. The mean duration of exposure of the asbes tos workers with lung or pleural cancers was five years longer in duration than that found in the talc group with similar malignancies. In addition, other components in the asbes tos dust exposure such as the presence of metallic cations may also be a factor to ac count for the difference in incidence be tween the two groups. Cardnoma of toe gas trointestinal tract and peritoneum, of which there were seven cases, showed a sig nificantly greater incidence in toe observed as compared to toe expected in US white males. Death due to cor pulmonale was ob served in only two individuals. The low inridonce of cor pulmonale as a cause of death as compared to the high incidence of pulmo nary and gastrointestinal cardnoma may be ascribed to a lower level of asbestos dust ex posure occurring over a longer period of time. M. H. Zalri. MD. Department of Environmental Medicine. State University of New York. Downstate Medical Center. New York, assisted in the statisti cal analysis of data. References 1.'Klcinfeld. M.; Messitc, J.: and Shapiro, X: Clinical, Radiological and Physiological Findings in Asbestosis. Arch Inem Med 117:813, 1966. 2. Bader, MJS.; Bader, R.A.; and Selikoff, XX: Pulmonary Function in Asbestosis of Luna, Amer J Med 30:235, 19SL 3. Selikoff, IX; Chur?, J.: and Hammond, E.C.: Asbestos Exposure and Neoplasia, JAMA 188:22. 1964, 4. Kleinfeld, M.. et al: Mortality Among Talc Miners and Millers in New York State, Arch Envi ron Health 14:663-667,1967. 5. Heard, B.E.: and Williams, R.: The Pathology of Asbestosis With Reference to Lung Function, Thorax 16:264, 1961. 6. Gilson, J.C.: Changing Hazards of Exposure to Asbestos Dust, presented at Conference on Biologi cal Effects of Asbestos, New York Academy of Sciences, New York, Oct 19-21,1964. Arch Environ Health--Vol 15, Aug 1967 CHEV B8B 0003199