Follow-up study of chrysotile asbestos textile workers: Cohort mortality and case-control analyses

Previous studies of mortality among white males employed in a Charleston, South Carolina asbestos textile plant using chrysotile demonstrated significant excess mortality due to asbestos-related disease and a steep exposure-response relationship for lung cancer. This cohort was further studied by adding 15 years of follow-up and including mortality among white female and black male workers. Nested case-control analyses were undertaken to further explore possible differences in lung cancer risk by textile operation as well as possible confounding by mineral oil exposures. Preliminary data for white males have been previously published. White males experienced statistically significant excess mortality due to lung cancer (standardized mortality ratio [SMR] = 2.30; confidence interval [CI] = 1.88–2.79), all causes (SMR = 1.48; CI = 1.38–1.58), all cancers (SMR = 1.50; CI = 1.29–1.72), diabetes mellitus (SMR = 2.05; CI = 1.18–3.33), heart disease (SMR = 1.41; CI = 1.26–1.58), cerebrovascular disease (SMR = 1.50; CI = 1.08–2.02), pneumoconiosis and other respiratory diseases (SMR = 4.10; CI = 3.10–5.31), and accidents (SMR = 1.49; CI = 1.15–1.91). Among white females, statistically significant excesses occurred for lung cancer (SMR = 2.75; CI = 2.06–3.61), all causes (SMR = 1.21; CI = 1.11–1.32), pneumoconiosis and other respiratory diseases (SMR = 2.40; CI = 1.53–3.60), and other respiratory cancers (SMR = 14.98; CI = 4.08–38.7). Among the total cohort of black males, the only statistically significant excess observed was for pneumoconiosis (SMR = 2.19; CI = 1.23–3.62). Based on historical exposure measurements at the plant, there was a positive exposure-response relationship for both lung cancer and pneumoconiosis. Data for the entire cohort demonstrate an increase in the lung cancer relative risk of 2–3% for each fiber/cc-year of cumulative chrysotile exposure. This relationship was more consistent for the white male workers. The excess risk for lung cancer among white males and females appeared to occur at cumulative exposures lower than those for black males. Possible reasons for the lesser lung cancer risk among black males include less smoking and differences in airborne fiber characteristics experienced by black males as a result of plant job placement patterns. The case-control analysis found employment in preparation and carding operations (where most of the black males worked) to be associated with a slightly reduced lung cancer risk, although not statistically significant, whereas spinning and twisting employment was associated with a statistically significant increased lung cancer risk compared to other plant operations. Airborne fiber size data, determined by transmission electron microscopy, demonstrated slightly longer fibers in spinning and twisting compared to other textile operations. Case-control analyses demonstrated little effect of mineral oil exposures on the lung cancer exposure-response estimates. Two deaths due to mesothelioma were observed among this cohort.     

Cancer risks among iron and steel workers in Anshan,China, part I: Proportional mortality ratio analysis

A standardized proportional mortality ratio (SPMR) study of 8,887 deaths during 1980–1989 among male workers in a large integrated iron-steel complex in Anshan, China, was conducted to provide clues to occupational risk factors. Accidents and cancer accounted for a higher proportion of deaths among the iron-steel workers than among the general male population (SPMR = 1.21; 95% CI = 1.12–1.31 and 1.14; 95% CI = 1.10–1.18, respectively). Among all workers, SPMRs were significantly elevated for stomach, lung, and colorectal cancers (SPMR = 1.37, 1.37, 1.38, respectively), but not other cancers. Risks of stomach cancer appeared to be highest among workers employed in jobs with exposure to iron and coal dust, whereas significant increases in colorectal cancer were seen for loading and other dusty jobs and for administrative and sedentary jobs without dust exposure. Risks of lung cancer appeared increased for a variety of jobs throughout the complex, especially those with probable high levels of exposure to polycyclic hydrocarbons and asbestos. Risk of esophageal cancer was significantly elevated for fire-resistant brick makers, and risk of nonmalignant respiratory disease was significantly elevated for those employed as furnace workers, foundry workers, and fire-resistant brick makers. (This article is a US Government work and, as such, is in the public domain in the United States of America.) © 1996 Wiley-Liss, Inc.     

Mortality among California highway workers

Standardized proportional mortality ratios (PMR) were computed for a population of highway workers. Hazards of highway maintenance work include exposure to solvents, herbicides, asphalt and welding fumes, diesel and auto exhaust, asbestos, abrasive dusts, hazardous material spills, and moving motor vehicles. Underlying cause of death was obtained for 1,570 workers who separated from the California Department of Transportation between 1970 and 1983, and who died in California between 1970 and 1983 (inclusive). Among 1,260 white males, the major findings were statistically significant excesses of cancers of digestive organs (PMR = 128), skin (PMR = 218), lymphopoietic cancer (PMR = 157), benign neoplasms (PMR = 343), motor vehicle accidents (PMR = 141), and suicide (PMR = 154). Black males (N = 66) experienced nonsignificant excesses of cancer of the digestive organs (PMR = 191) and arteriosclerotic heart disease (PMR = 143). Among 168 white females, deaths from lung cancer (PMR = 189) and suicide (PMR = 215) were elevated. White male retirees, a subgroup with 5 or more years of service, experienced excess mortality due to cancers of the colon (PMR = 245), skin (PMR = 738), brain (PMR = 556), and lymphosarcomas and reticulosarcomas (PMR = 514). Deaths from external causes (PMR = 135) and cirrhosis of the liver (PMR = 229) were elevated among white males with a last job in landscape maintenance. White males whose last job was highway maintenance experienced a deficit in mortality from circulatory diseases (PMR = 83) and excess mortality from emphysema (PMR = 250) and motor vehicle accidents (PMR = 196). Further epidemiologic and industrial hygiene studies are needed to confirm the apparent excess mortality and to quantify occupational and nonoccupational exposures. However, reduction of recognized hazards among highway maintenance workers is a prudent precautionary measure.     

A proportionate mortality study of granite cutters

Several recent studies (animal and human) have suggested an association between lung cancer and silica exposure. To test the hypothesis, we have studied death benefit records of 1,905 members of the Granite Cutters Union. A proportionate mortality analysis (PMR) was conducted, using U.S. deaths as a comparison population. Statistically (PMR) was conducted, using U.S. deaths as a comparison population. Statistically significant excesses were observed for death from nonmalignant respiratory significant excesses were observed for death from nonmalignant respiratory disease (largely silicosis) (183 obs, 43.7 exp) and for tuberculosis (largely silicotuberculosis) (262 obs, 19.3 exp). Other significant excesses were observed for bone cancer (6 obs, 1.9 exp) and arthritis (5 obs, 1.5 exp). A significant decrease was observed for leukemia (5 obs, 13.0 exp). For lung cancer a slight but nonsignificant excess was observed (97 obs, 81.1 exp, PMR = 1.19, 95% CI 0.97-1.46). A proportionate cancer mortality analysis (PCMR) showed similar results for lung cancer (PCMR = 1.09, 95% CI 0.89-1.33). Lung cancer mortality also failed to show any trend with either calendar time or duration of exposure. Although no significant excess of lung cancer was observed for the entire silica-exposed cohort, there was an indication that those who were silicotic had an excess risk of lung cancer, based on a review of contributing causes on the death certificate.     

Truck drivers and heart disease in the United States, 1979-1990

BACKGROUND: Studies of truck drivers and cardiovascular disease (CVD), myocardial infarction, or ischemic heart disease (IHD) are limited, although studies of other professional drivers reported increased risk. METHODS: US mortality data from 1979 to 1990 for ages 15-90 were used to calculate proportional mortality ratios (PMRs) for heart disease and lung cancer for short and long haul truck drivers. Analysis was performed for Black (998 short haul and 13,241 long haul) truck drivers and White (4,929 short and 74,315 long haul) truck drivers separately. RESULTS: The highest significantly elevated proportionate heart disease (IHD, acute myocardial infarction (AMI), and other forms of heart disease) and lung cancer mortality was found for White and Black male long haul truck drivers age 15-54. Mortality was not significantly elevated for short haul truck drivers of either race or gender, nor for truck drivers who died after age 65, except for lung cancer among White males. An indirect adjustment suggested that smoking could explain the excess IHD mortality, but no direct data for smoking or the other known risk factors for heart disease were available and occupational exposures were not measured. CONCLUSIONS: The highest significant excess proportionate mortality for lung cancer, IHD and AMI was found for long haul truck drivers who were under age 55 at death. A cohort or longitudinal study of heart disease among long haul truck drivers, that obtains data for occupational exposures as well as lifestyle risk factors, could help explain inconsistencies between the findings of this and previous studies.     

油毡工人比例死亡比的研究

对全国20个油毡厂工人的癌症和其它几种慢性病进行了比例死亡比的研究。接触组按照接触沥青种类分为混合组和石油组,与对照组比较,男性接触组和混合组心血管病的SPMR分别为1.53(p<0.05)和1.45(p<0.05)。接触组和混合组、石油组肺癌超出量尤为显著,SPMR分别为3.38(P<0.01)和2.8l(P<0.01)、4.93(P<0.01)。混合组重、中暴露工作区SPMR分别为3.14(P<0.01)、3.03(P<0.05),轻暴露工作区SPMR不明显,重暴露区食道癌SPMR为2.02(P<0.01)。石油组重中暴露工作区肺癌SPMR分别为5.39(P<0.01)、4.67(P<0.01),均明显高于对照组。同时也进行了癌症比例死亡比(PCMR)的研究,与SPMR研究结果相似,说明油毡厂生产作业工人的肺癌发病与其职业有很强的联系。     

Mortality from lung cancer and respiratory disease among pottery workers exposed to silica and talc

A cohort mortality study of white men employed for at least one year between 1939 and 1966 at three plants of a single United States company was conducted to evaluate the risk of lung cancer and nonmalignant respiratory disease among workers exposed to silica dust and nonfibrous (nonasbestiform) talc in the manufacture of ceramic plumbing fixtures. Follow-up of 2,055 men through January 1, 1981, indicated a substantial excess of nonmalignant respiratory disease among those with high levels of exposure to silica dust (standardized mortality ratio = 2.26). The risk of nonmalignant respiratory disease rose with the number of years exposed, was not further enhanced by talc exposure, and appeared to be appreciably lower among those exposed in more recent time periods. For lung cancer, men exposed to high levels of silica dust with no talc exposure had a nonsignificant standardized mortality ratio of 1.37. However, those exposed to nonfibrous talc in addition to high levels of silica had a significant 2.5-fold excess risk of lung cancer. Among this group, the lung cancer standardized mortality ratio rose with increasing years of talc exposure to 3.64 among those exposed for 15 or more years. Although the role of silica as a cofactor cannot be ruled out, these data suggest that nonfibrous talc exposure is associated with excess lung cancer risk.     

Asbestos disease in sheet metal workers: the results of a proportional mortality analysis

The results of a proportional mortality analysis of a cohort of sheet metal workers who have only intermittent exposure to asbestos demonstrates a significant excess of cancer at the three sites most frequently associated with asbestos: lung, colon and rectum, and the mesothelium. No excess nonmalignant respiratory disease was detected. These data strongly suggest that significant asbestos-related disease is present in populations with secondary exposure to asbestos and emphasize the importance of considering possible asbestos-related disease when treating patients with a history of employment in the construction industry.     

Respiratory disease mortality patterns among South African iron moulders.

To assess the influence of foundry exposure on malignant and non-malignant respiratory disease, the proportional mortality ratio (PMR) was used to compare the cause of death distributions of the 578 dead members of the Iron Moulders Society of South Africa, recipients of the union's death benefit fund between 1961 and 1983. Comparisons were made with the age and period specific white male deaths. For the 419 members where job information was available, the influence of occupation (journeyman, production moulder) was assessed using different techniques--the relative proportional mortality ratio (RPMR), the mortality odds ratio (MOR), and the proportional cancer mortality ratio (PCMR) for comparison. Excess PMRs were found for cancer of the trachea, bronchus, and lung (1.71, p = 0.03; Poisson one sided test) for those over 65 and for non-malignant respiratory disease (1.58, p = 0.01) and for injuries and poisonings (2.61, p less than 0.0001) in those under 65. Reduced PMRs were found for all cancers (0.75, p = 0.03) and all circulatory disease (0.91, p = 0.12) in those under 65. When comparing job types, raised risks were obtained for journeymen using all methods (RPMR, MOR, PCMR) but the small cell sizes rendered the results non-significant. The raised PMRs due to respiratory disease are unlikely to be due to smoking because of a poor association with other causes of death related to smoking. A more likely explanation is that these excess rates for malignant and non-malignant respiratory disease are due to exposure to the foundry environment. Of additional concern are the high PMRs due to injuries and poisonings, which could be related to the high accident rates in the iron and steel industry.     

Respiratory disease mortality patterns among South African iron moulders

To assess the influence of foundry exposure on malignant and non-malignant respiratory disease, the proportional mortality ratio (PMR) was used to compare the cause of death distributions of the 578 dead members of the Iron Moulders Society of South Africa, recipients of the union's death benefit fund between 1961 and 1983. Comparisons were made with the age and period specific white male deaths. For the 419 members where job information was available, the influence of occupation (journeyman, production moulder) was assessed using different techniques--the relative proportional mortality ratio (RPMR), the mortality odds ratio (MOR), and the proportional cancer mortality ratio (PCMR) for comparison. Excess PMRs were found for cancer of the trachea, bronchus, and lung (1.71, p = 0.03; Poisson one sided test) for those over 65 and for non-malignant respiratory disease (1.58, p = 0.01) and for injuries and poisonings (2.61, p less than 0.0001) in those under 65. Reduced PMRs were found for all cancers (0.75, p = 0.03) and all circulatory disease (0.91, p = 0.12) in those under 65. When comparing job types, raised risks were obtained for journeymen using all methods (RPMR, MOR, PCMR) but the small cell sizes rendered the results non-significant. The raised PMRs due to respiratory disease are unlikely to be due to smoking because of a poor association with other causes of death related to smoking. A more likely explanation is that these excess rates for malignant and non-malignant respiratory disease are due to exposure to the foundry environment. Of additional concern are the high PMRs due to injuries and poisonings, which could be related to the high accident rates in the iron and steel industry.     

Lung function, respiratory symptoms, and mortality: results from the Busselton Health Study

PURPOSE: This study examines the association between lung function [percentage predicted FEV, (forced expiratory volume in 1 s)] and respiratory symptoms (asthma, bronchitis, wheeze, dyspnea) and mortality from all causes; coronary heart disease, stroke, cancer, and respiratory disease in a cohort of 2,100 men and 2,177 women in the Busselton Health Study followed for 20-26 years for mortality. METHODS: A total of 840 men and 637 women died during the follow-up period, and Cox proportional hazards regression was used to assess the relationships between risk factors and mortality. RESULTS: Lung function was significantly and independently predictive of mortality from all causes, coronary heart disease, cancer, and respiratory disease in both men and women, and of mortality from stroke in women. There was evidence that, among men, the association was stronger in current and former smokers as compared to those who never smoked. After adjustment for age, smoking, lung function, coronary heart disease, blood pressure, treatment for hypertension, total cholesterol, body mass index, and alcohol consumption, dyspnea was significantly related to total mortality in men and women and to respiratory disease mortality in men, and asthma was significantly related to respiratory disease mortality in women. CONCLUSIONS: Lung function is associated with mortality from many diseases independent of smoking and respiratory symptoms. Although most respiratory symptoms are associated with smoking and lung function, after controlling for smoking and lung function, only dyspnea is associated with mortality from nonrespiratory causes.     

Exposures and mortality among chrysotile asbestos workers. Part II: mortality

A retrospective cohort mortality study was conducted among a cohort of 1,261 white males employed one or more months in chrysotile asbestos textile operations and followed between 1940 and 1975. Statistically significant excess mortality was observed for all causes combined (standardized mortality ratio [SMR] = 150), lung cancer (SMR = 135), diseases of the circulatory system (SMR = 125), nonmalignant respiratory diseases (SMR = 294), and accidents (SMR = 134). Using estimated fiber exposure levels in conjunction with detailed worker job histories, exposure-response relationships were investigated. Strong exposure-response relationships for lung cancer and asbestos related non-malignant respiratory diseases were observed. Compared with data for chrysotile miners and millers, chrysotile textile workers were found to experience significantly greater lung cancer mortality at lower lifetime cumulative exposure levels. Factors such as differences in airborne fiber characteristics may partially account for the large differences in exposure response between textile workers and miners and millers.     

石棉暴露地区的居民死因分布研究

目的探讨石棉暴露地区的人群死因分布情况。方法以慈溪市居民死因资料为基础,对石棉暴露地区居民死亡的年龄段、性别、疾病等变量进行分类,计算预期死亡数;根据死亡登记数据统计实际死亡数,然后计算标化比例死亡比(SPMR)和95%可信区间(95%CI)。结果石棉制品加工集中的城镇女性因呼吸系统疾病死亡120例,SPMR为1.85(95%CI:1.53～2.21);肺癌死亡65例,SPMR为1.56(95%CI:1.21～1.99)。结论慈溪地区的呼吸系统疾病和肺癌高发可能与石棉接触有关。     

Silicosis and lung cancer: a mortality study of compensated men with silicosis in New South Wales, Australia

BACKGROUND: Lung cancer mortality has been found to be in excess in several groups with silicosis, but allowance for smoking was not always possible. We investigated the lung cancer mortality in men with silicosis in New South Wales, Australia, who were compensated, making allowance for smoking habits. METHODS: A mortality study of 1467 men with silicosis in New South Wales who were compensated was carried out comparing observed mortality with that expected from the New South Wales death rates adjusting for age and period. Their smoking habits were compared with national survey smoking rates and the expected number of lung cancer deaths adjusted for smoking. Cases were coded for occupation and industry. RESULTS: The observed mortality was higher than expected, but the only site of cancer showing a significant excess was the lung. The group with silicosis had smoked more than the national rates. After adjusting for smoking the standardized mortality ratio for lung cancer was 1.9 (95% confidence interval 1.5-2.3). Although there were differences in lung cancer mortality between industries and occupations, these differences were not statistically significant. CONCLUSIONS: The excess lung cancer death rate may not be entirely due to silica exposure because compensation may have been influenced by the presence of chronic obstructive respiratory disease and there is some evidence that the presence of this disease increases lung cancer risk independently of smoking.     

A retrospective cohort mortality study of males mining and milling attapulgite clay

To evaluate the possible health effects of occupational exposure to a nonasbestos mineral fiber, a cohort of 2,302 males employed for at least 1 month between 1940 and 1975 at an attapulgite (clay fiber) mining and milling facility was followed through 1975. A significant deficit of mortality (SMR = 43, 90% CI 23-76) from nonmalignant respiratory disease (NMRD) was observed for the cohort based on age-, calendar year-, and race-specific rates for U.S. males. A marked deficit of NMRD was seen regardless of presumed dust exposure level, induction-latency period, or duration employed. A statistically significant excess of mortality from lung cancer was observed among whites (SMR = 193, 90% CI 121-293), but a deficit occurred among nonwhites (SMR = 53, 90% CI 21-112). Lung cancer risk in either race was not altered substantially with presumed dust exposure level, induction-latency period, or duration employed with one exception-those employed for at least 5 years in high-exposure-level jobs.     

Lung cancer risk among refractory brick workers exposed to crystalline silica: a retrospective cohort study.

We conducted a retrospective cohort study among 1,022 refractory brick workers exposed to crystalline silica. Mortality from lung cancer (SMR = 1.77) and respiratory diseases (SMR = 3.15) was elevated in workers first employed less than or equal to 1957 who are likely to have shared the highest exposure to crystalline silica. Workers with at least 19 years of cumulative employment in the plant experienced particularly increased risks for lung cancer (SMR = 2.01) and respiratory diseases (SMR = 3.89). Relative mortality from these specific causes increased with years since first employment (that is, first exposure) and decreased with age at first employment. Indirect adjustment for smoking habits and the lack of excess mortality from cardiovascular diseases and emphysema indicated little effect of smoking on the increased risks for lung cancer and respiratory diseases.     

Suicide,cancer, and other causes of death among california veterinarians, 1960-1992

Previous studies reporting on mortality patterns in veterinarians have been restricted to deaths among white male veterinarians. In an effort to examine the mortality of male and female veterinarians of all races, we conducted a standardized proportionate mortality ratio (SPMR) analysis of 450 California veterinarians who died between January 1960 and December 1992. In comparison to State of California general population statistics, white male veterinarians had significantly elevated mortality from malignant melanoma of the skin (SPMR 3.47, 95% CI 1.74. 6.94), cancer of the large intestine (SPMR 1.74, 95% CI 1.04, 2.09), rheumatic heart disease (SPMR 3.50, 95% CI 1.90, 6.43), and suicide (SPMR 2.50, 95% CI 1.84, 3.38). White female veterinarians had significantly elevated mortality from suicide (SPMR 5.89, 95% CI 3.02, 11.48). We also examined veterinary mortality for different lengths of time in the profession. Significantly elevated SPMRs were noted for suicide in veterinarians in the profession for less than 30 years; deaths due to malignant melanoma of the skin and rheumatic heart disease in veterinarians in the profession 20 years or more; and cancer of the large intestine in veterinarians in the profession 30 years or more. Because of significant findings in mortality from suicide among veterinarians of both sexes, it was recommended that future studies and efforts toward suicide prevention include both male and female veterinarians.     

The mortality of lead smelter workers: an update.

OBJECTIVES. Mortality studies of lead workers have shown excesses of nonmalignant renal disease and cerebrovascular disease. Animal studies and one human study have shown excess kidney cancer. We have updated a mortality study of male lead smelter workers (n = 1990). METHODS. An analysis was conducted using standard life table techniques. The updated analysis added 11 years of follow-up and 363 new deaths. RESULTS. The original study had found elevated but nonsignificant risks for kidney cancer, stroke, and nonmalignant renal disease, probably attributable to lead exposure. Deaths from accidents and nonmalignant respiratory disease were significantly elevated, but probably not as a result of lead exposure. In the updated study, no new deaths from nonmalignant renal disease occurred (9 observed, standardized mortality ratio = 1.21). Three more deaths from kidney cancer were observed, yielding a standardized mortality ratio of 1.93 (9 observed, 95% CI = 0.88, 3.67), which increased for those who had worked in areas with the highest lead exposure (8 observed, standardized mortality ratio = 2.39, 95% CI = 1.03, 4.71). Cerebrovascular disease remained elevated for those with more than 20 years of exposure (26 observed, standardized mortality ratio = 1.41, 95% CI = 0.92, 2.07). CONCLUSIONS. This cohort with high lead exposure showed a diminishing excess of death from nonmalignant renal disease, a continued excess from kidney cancer, and an excess of cerebrovascular disease only in those with longest exposure to lead.     

Mortality of a cohort of U.S. workers employed in the crushed stone industry, 1940-1980

The mortality of 3,246 males who had been employed 1 or more years during 1940-1980 at 20 crushed stone operations was evaluated for possible association between employment and death from lung cancer, pneumoconiosis, and other respiratory diseases. Four deaths were attributed to pneumoconiosis. Based on available work histories, at least two of these deaths were probably due to dust exposures in the crushed stone industry. Mortality attributed to pneumoconiosis and other nonmalignant respiratory diseases, including chronic obstructive lung disease, was significantly increased overall (SMR: 1.98; 95%CI: 1.21-3.05), and especially so for a subcohort of crushed stone workers that processed granite (SMR: 7.26; 95%CI: 1.97-18.59). With regard to lung cancer, overall SMRs were elevated (although not statistically significant). Analyzed by rock type, there was a significantly elevated lung cancer SMR among granite workers with at least 20 years latency (SMR: 3.35; 95%CI: 1.34-6.90). Although not definitive, results of this study are consistent with the hypothesis that exposure to respirable silica dust is a risk factor for lung cancer.     

A case-control study of malignant and non-malignant respiratory disease among employees of a fiberglass manufacturing facility.

A case-control study was conducted to determine the influence of non-workplace factors on risk of respiratory disease among workers at the Owens-Corning Fiberglas plant in Newark, Ohio. Cases and controls were drawn from a historical cohort mortality study conducted on behalf of the Thermal Insulation Manufacturers Association (TIMA) of workers employed at Newark for at least one year between 1 January 1940 and 31 December 1963 and followed up to the end of 1982. The TIMA study reported a statistically significant increase in respiratory cancer (compared with national death rates). Interviews were completed for 144 lung cancer cases and 299 matching controls and 102 non-malignant respiratory disease cases and 201 matching controls. Unadjusted odds ratios (ORs) were used to assess the association between lung cancer or non-malignant respiratory disease and birthplace, education, income, marital state, smoking with a duration of six months or more, age at which smoking first started, and duration of smoking. Only the smoking variables were statistically significant. For lung cancer, of the variables entered into a conditional logistic regression model, only the smoking OR of 23.4 (95% CI 3.2-172.9) was statistically significant. For non-malignant respiratory disease no variables entered into the final model were statistically significant. Results of the interview portion of our case-control study clearly indicate that smoking is the most important non-workplace factor for risk of lung cancer in this group of workers. Smoking does not seem to play as important a part, however, for non-malignant respiratory disease. Prevalence of cigarette smoking at the Newark plant was estimated for birth cohorts by calendar year. Corresponding data for the United States were compiled from national smoking surveys. Prevalence of cigarette smoking for Newark in 1955 appears to be sufficiently greater than the corresponding United States data in 1955 to suggest that some of the previously reported excess of lung cancer for Newark based on United States mortality may be accounted for by differences in the prevalence of cigarette smoking between white men in Newark and those in the United States as a whole.