Trends in US smoking rates in occupational groups: the National Health Interview Survey 1987-1994

It is unknown if reductions in U.S. adult smoking rates are uniform across occupational groups. The National Health Interview Survey (NHIS) is a multistage area probability cross-sectional survey of the U.S. civilian population. Data on occupational and smoking status were collected on 141122 adult participants from the 1987, 1988, and 1990 -1994 NHIS annual surveys. Overall smoking rates ranged from 58% in roofers to 4% in physicians, with higher rates found among blue collar professions. There were reductions in smoking from 1987-1994 within 72% of occupational groups; 19 of these downward trends were significant and occurred exclusively within white collar professions. Blue collar workers continue to smoke in large numbers, whereas white collar workers report lower rates along with corresponding significant downward trends in rates among selected occupational groups. The development of effective smoking prevention strategies targeting blue collar groups is needed.     

Lung cancer mortality in a Dutch cohort of asphalt workers: evaluation of possible confounding by smoking

BACKGROUND: Using data from a Dutch cohort of workers in road construction and asphalt mixing companies, this article describes possible confounding of the association between exposure to bitumen fume and lung cancer mortality by smoking. METHODS: A retrospective cohort of 3,714 workers with at least one season of employment was identified. Semi-quantitative exposure to bitumen fume was assessed by a job-exposure matrix. Information on smoking habits was available for a sub-cohort of 1,138 workers, who underwent medical examinations by the occupational health services in the past. RESULTS: Smoking habits differed between occupational title groups and there was a positive association between cumulative exposure and smoking. Internal analyses using the non-exposed subjects as reference category, showed a positive association between semi-quantitative bitumen fume exposure and lung cancer risk. After adjusting for differences in smoking habits, all relative risks were reduced, but a weak positive association could still be observed. CONCLUSION: Confounding by smoking on the association between exposure to bitumen fume and lung cancer mortality is possible, although the positive trend (not statistically significant) for lung cancer mortality remained. Only a nested case-control study may allow proper treatment of potential (residual) confounding by smoking in this population.     

Cigarette smoking and occupational status: 1977 to 1990.

OBJECTIVES. In this study we examined the relationship between occupational status and smoking habits in men and women during the period from 1977 to 1990. METHODS. Cigarette smoking and occupational history were obtained from 8045 men and women who served as controls for a hospital-based study of tobacco-related diseases. RESULTS. There was an association between increasing occupational status and tobacco exposure in men, but not in women. The quit rate increased over time in all sex-occupational groups except for male laborers, whose quit rate remained constant. Nicotine-dependent smokers are likely to find it difficult to quit. Male nicotine-dependent smokers were consistently found in greater numbers among blue collar workers throughout the study period. Initially, female nicotine-dependent smokers were more often found among blue collar workers, but in recent years became more frequent among white collar workers. CONCLUSION. These trends provide clues to the future epidemiological distribution of lung cancer and other tobacco-related diseases. An understanding of gender differences in the occupational profile of cigarette smokers can provide guidelines for effective antismoking interventions.     

Smoking and degree of occupational exposure: are internal analyses in cohort studies likely to be confounded by smoking status?

Occupational cohort studies are usually carried out without the benefit of information on smoking habits of cohort members. One common approach to avoid confounding bias related to smoking habits is to carry out an internal analysis, comparing workers with different degrees of occupational exposure. The premise behind this approach is that within a cohort there is unlikely to be correlation between degree of exposure and smoking habits. If this were untrue, smoking could confound the disease-exposure relationships. Our purpose was to verify the premise. The study sample consisted of 857 French-Canadian men born between 1910 and 1930, with 11 or fewer years of education, and interviewed around 1980 in the context of an occupational cancer case-control study. For each man we had information on smoking habits, job history, and a history of the chemicals he was exposed to in each of his jobs. We computed two indices of the dirtiness of workers' job histories: one based on the job titles held by the man and a second based on the degree of exposures to workplace substances. There was no correlation between these indices of job dirtiness and smoking history. We also examined the smoking-exposure relationship among the subsets of men who had been occupationally exposed to ten especially noticeable substances. Within the subsets, there was no indication of a consistent difference among the smoking subgroups in level or duration of exposure to these index substances. These findings do not support the view that nonsmokers sought out cleaner job environments than smokers; they imply that internal analyses of "dose-response" in cohort studies are unlikely to be seriously confounded by smoking habits.     

Analysis of the relationship between smokeless tobacco and cancer based on data from the National Mortality Followback Survey.

This study investigates the potential link between the use of smokeless tobacco and oral cancer and cancer of digestive organs. The combined data of the National Mortality Followback Survey (NMFS), a probability sample of the U.S. deaths, and the coincident National Health Interview Survey (NHIS), a probability sample of the living, non-institutionalized U.S. population, are used to compute risk estimates for cancer, oral cancer, and cancer of the digestive organs associated with use of smokeless tobacco based on a cross sectional study design, simultaneously controlled for potential confounding from active smoking, alcohol consumption, and occupational exposure. Use of smokeless tobacco (either as snuff or chewing tobacco) does not increase the risk of oral cancer or cancer of the digestive organs. Alcohol emerges as a major risk factor for oral cancer with a strong dose-response relationship between the amount of drinking and risk. The same is true to a lesser extent for cancer of the digestive organs. Smoking is associated with increased risk of oral cancer but not of cancer of the digestive organs. Blue collar, technical, and service workers have significantly increased risk of cancer of the digestive organs relative to professional, managerial, and clerical workers, but not of oral cancer. Differences between findings based on the NMFS/NHIS and those obtained from other data very likely are due to inadequate control for confounding. Other reasons for differences between the NMFS/NHIS data and other studies are discussed.     

Lung cancer: is there an association with socioeconomic status in The Netherlands?

STUDY OBJECTIVE--To evaluate if there are differences in lung cancer incidence between socioeconomic groups in the Netherlands and if so, if smoking habits and other lifestyle characteristics could explain these differences. DESIGN--Prospective cohort study. Baseline measurement included information on socioeconomic status, smoking habits, and other covariates by means of a self-administered questionnaire. Follow up was established by computerised record linkage to cancer registries and a pathology register. SETTING--Population originating from 204 municipalities in The Netherlands. PARTICIPANTS--58,279 men aged 55-69 years in September 1986. After 3.3 years of follow up 490 microscopically confirmed incident lung cancer cases were detected. MAIN RESULTS--An inverse association between lung cancer risk and highest level of education was found, which persisted after adjustment for age, smoking, dietary intake of vitamin C, beta-carotene and retinol (rate ratio (RR) highest/lowest level of education = 0.52, 95% CI 0.33, 0.82, trend p < 0.001). Men with a lower white collar profession had a significantly lower relative rate of lung cancer compared with blue collar workers (RR = 0.66, 95% CI 0.47, 0.96), but after adjustment for smoking habits this difference was reduced (RR = 0.73, 95% CI 0.51, 1.08). CONCLUSIONS--There is an inverse association between highest level of education and lung cancer, which is still apparent after adjustment for age, smoking, dietary intake of vitamin C, beta-carotene and retinol. The significantly lower lung cancer risk of lower white collar workers compared with the risk of blue collar workers could be partially explained by smoking habits.     

Prospective evaluation of associations between hearing sensitivity and selected cardiovascular risk factors

The prospective decline of hearing sensitivity was evaluated in an occupational cohort of university blue collar workers in relation to age, gender, occupational and nonoccu-pational noise exposure, smoking, blood pressure, and cholesterol. Each of these were associated with loss of hearing sensitivity univariately. When controlling for age and historical noise exposure in a multiple regression model, systolic blood pressure and cholesterol level were independently associated with decline in auditory sensitivity.     

Smoking imputation and lung cancer in railroad workers exposed to diesel exhaust

BACKGROUND: An association between diesel exhaust exposure and lung cancer mortality in a large retrospective cohort study of US railroad workers has previously been reported. However, specific information regarding cigarette smoking was unavailable. METHODS: Birth cohort, age, job, and cause of death specific smoking histories from a companion case-control study were used to impute smoking behavior for 39,388 railroad workers who died 1959-1996. Mortality analyses incorporated the effect of smoking on lung cancer risk. RESULTS: The smoking adjusted relative risk of lung cancer in railroad workers exposed to diesel exhaust compared to unexposed workers was 1.22 (95% CI = 1.12-1.32), and unadjusted for smoking the relative risk was 1.35 (95% CI = 1.24-1.46). CONCLUSIONS: These analyses illustrate the use of imputation in record-based occupational health studies to assess potential confounding due to smoking. In this cohort, small differences in smoking behavior between diesel exposed and unexposed workers did not explain the elevated lung cancer risk.     

Occupational causes of laryngeal cancer.

In a case-control study of all new cases of laryngeal cancer in Denmark from 1980 to 1982, 326 cases and 1134 community selected controls participated. Questionnaires were used to obtain information on education, occupation, and number of occupational exposures as well as smoking and drinking habits. High risk ratios for laryngeal cancer were found for semiskilled and unskilled workers, workers exposed to dust, out of doors workers, drivers, and people working in the cement industries and port services. The study hypothesis was that exposure to chromium or nickel increases the incidence rate of laryngeal cancer. No support for this was found concerning chromium, but exposure to nickel had a statistically significant risk ratio of 1.7.     

Occupation and male lung cancer: a case-control study in northern Sweden

Using a case-control study comprising about 600 men with lung cancer in northern Sweden the potential risk of different occupations and groups of occupations was studied. Longitudinal data concerning occupation, employment, and smoking habits were obtained by questionnaires. Some occupational groups (underground miners, copper smelter workers, electricians, and plumbers) exposed to previously known lung carcinogenic agents such as radon daughters, arsenic, and asbestos, had considerably increased odds ratios, which persisted after adjustment for smoking. A slightly raised odds ratio was observed in a group of blue collar workers potentially exposed to lung carcinogenic agents; this rise in the group as a whole mainly disappeared after adjustment for smoking. Farmers and foresters had strikingly low odds ratios, which could only partly be explained by their more moderate smoking habits. The population aetiological fraction attributable to occupation was estimated as 9%.     

Occupation and male lung cancer: a case-control study in northern Sweden.

Using a case-control study comprising about 600 men with lung cancer in northern Sweden the potential risk of different occupations and groups of occupations was studied. Longitudinal data concerning occupation, employment, and smoking habits were obtained by questionnaires. Some occupational groups (underground miners, copper smelter workers, electricians, and plumbers) exposed to previously known lung carcinogenic agents such as radon daughters, arsenic, and asbestos, had considerably increased odds ratios, which persisted after adjustment for smoking. A slightly raised odds ratio was observed in a group of blue collar workers potentially exposed to lung carcinogenic agents; this rise in the group as a whole mainly disappeared after adjustment for smoking. Farmers and foresters had strikingly low odds ratios, which could only partly be explained by their more moderate smoking habits. The population aetiological fraction attributable to occupation was estimated as 9%.     

Incidence of laryngeal cancer and exposure to acid mists.

To determine the relation between exposure to acid mist and laryngeal cancer, the smoking habits, drinking habits, and incidence of laryngeal cancer of 879 male steelworkers exposed to acid mists during pickling operations was ascertained. Sulphuric acid mist was the primary exposure for most men in this cohort. These men had all worked in a pickling operation for a minimum of six months before 1965, with an average duration of exposure of 9.5 years. Exposures to sulphuric acid in the 1970s averaged about 0.2 mg/m3, and earlier exposures were probably similar. Interviews were conducted with all cohort members or their next of kin in 1986 and medical records of decedents were reviewed. Nine workers were identified who had been diagnosed as having laryngeal cancer, using a conservative case definition that required medical record confirmation for any case among decedents and confirmation by a physician for any case among live individuals. Using data from national surveys of cancer incidence as referent rates, 3.44 laryngeal cancers would have been expected. Excess smoking by the exposed cohort compared with the United States population resulted in an upward adjustment of the expected number of cases of laryngeal cancer to 3.92. The standardised incidence rate ratio for laryngeal cancer was 2.30 (9/3.92), with a one sided p value of 0.01 (assuming a Poisson distribution). The finding of excess laryngeal cancer in this cohort is consistent with four other studies published since 1981.     

Smoking behavior in trucking industry workers

BACKGROUND: In retrospective occupational studies, the degree of confounding by smoking depends on variation in smoking among job-related exposure groups. We assessed the relationship between job title and smoking behavior as part of a study on occupational exposures and lung cancer. METHODS: A questionnaire on smoking was mailed to a sample of 11,986 trucking industry workers. Company records were used to gather other relevant information. RESULTS: The response rate was 40.5%. Among white males, the age-adjusted prevalence of ever smoking was highest among longhaul truck drivers (67%) and lowest among clerks (44%). Smoking rates among workers with other job titles were similar. CONCLUSIONS: Our results will be used to adjust for the differences in smoking among job-related exposure groups when assessing the association between particulate matter exposure and lung cancer mortality. Our study also suggests that an assessment of methods to control for smoking should be considered in the design of retrospective occupational health studies.     

Incidence of laryngeal cancer and exposure to acid mists

To determine the relation between exposure to acid mist and laryngeal cancer, the smoking habits, drinking habits, and incidence of laryngeal cancer of 879 male steelworkers exposed to acid mists during pickling operations was ascertained. Sulphuric acid mist was the primary exposure for most men in this cohort. These men had all worked in a pickling operation for a minimum of six months before 1965, with an average duration of exposure of 9.5 years. Exposures to sulphuric acid in the 1970s averaged about 0.2 mg/m3, and earlier exposures were probably similar. Interviews were conducted with all cohort members or their next of kin in 1986 and medical records of decedents were reviewed. Nine workers were identified who had been diagnosed as having laryngeal cancer, using a conservative case definition that required medical record confirmation for any case among decedents and confirmation by a physician for any case among live individuals. Using data from national surveys of cancer incidence as referent rates, 3.44 laryngeal cancers would have been expected. Excess smoking by the exposed cohort compared with the United States population resulted in an upward adjustment of the expected number of cases of laryngeal cancer to 3.92. The standardised incidence rate ratio for laryngeal cancer was 2.30 (9/3.92), with a one sided p value of 0.01 (assuming a Poisson distribution). The finding of excess laryngeal cancer in this cohort is consistent with four other studies published since 1981.     

Exposure-response models based on extended follow-up of a cohort mortality study in the automobile industry

OBJECTIVE: This report describes the extended follow-up of a cohort of 46 399 automobile manufacturing workers with potential exposure to metalworking fluids (MWF). The outcomes of interest were cancers of the esophagus, stomach, colon, rectum, liver, pancreas, larynx, skin, prostate, and brain, as well as leukemia. Additional follow-up increased the power to detect modest elevations in mortality rates in association with specific types of MWF, including synthetic fluids not in widespread use until the 1970s. METHODS: Standardized mortality ratios (SMR) were computed for the most recent 10 years of follow-up, as well as for the entire study period. Adjusted relative risks (RR) were estimated in Poisson regression models with categorical variables for cumulative exposure to each type of MWF and in proportional hazards models with continuous exposure variables. RESULTS: Associations were found between straight MWF and esophageal, laryngeal and rectal cancer; soluble MWF and cancer of the esophagus, larynx, skin, and brain; synthetic MWF and cancer of the esophagus, liver, and prostate. The elevated RR values were modest in magnitude (1.5 to 2.0). SMR values were increased for stomach, liver, and pancreatic cancer and also for leukemia in the last 10 years of follow-up. The SMR values were also elevated for stomach and liver cancer among the persons recently hired. CONCLUSIONS: The results provide further evidence that exposure to metalworking fluids causes cancer among workers in automobile manufacturing. Although airborne exposures declined over the study period, this study suggests that modest risk of several digestive cancers, as well as prostatic cancer and leukemia, may persist at current levels of exposure to water-based metalworking fluids.     

Confounding by variable smoking habits in different occupational groups

Smoking habits of different occupational groups were studied in a sample of persons who participated in health screening examinations carried out by the mobile clinic of the Institute of Occupational Health (Helsinki, Finland). The sample consisted of 1 990 men and 1 044 women. The smoking habits of the study population as a whole conformed with those of the entire Finnish population. Distinct differences in smoking habits were found, however, in different occupational groups. The effect of smoking habits on tentative rate ratios of lung cancer in occupational groups were estimated with a procedure presented by Olav Axelson. The groups were selected from extreme ends of the smoking habit variable. Extreme estimates were taken to maximize the confounding effect of smoking. When occupational groups were contrasted with the general population, the confounding effect was found to be smaller than usually believed.     

Lack of relationship between occupational exposure to carbon disulfide and endocrine dysfunction: a six-year cohort study of the Japanese rayon workers

OBJECTIVES: A six-year prospective cohort study was conducted to clarify whether the current carbon disulfide (CS2) exposure level is low enough to prevent subclinical health impairment and/or to ameliorate health effects due to previous high exposure. This paper describes the follow-up results, exposure assessment, and effects on the endocrine system. METHODS: The study subjects were 432 male workers exposed to CS2 at one of the 11 rayon factories in Japan and 402 referent workers from the same factories, all of whom were examined in 1992-93. 251 CS2-exposed, 140 former-exposed and 359 referent workers participated in the follow-up survey (follow-up rate 89.9%) in 1998-99. Urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) at the end of a shift as internal exposure index and the time-weighted average CS2 concentration as external exposure index were measured twice a year from 1992-1993. By using various blood indices, we evaluated effects on thyroid, hypophysis, and gonad function, as well as effects on glucose metabolism. Information on potential confounding factors, such as age, smoking and alcohol drinking, were collected and adjusted for. RESULTS: When the individual exposure level was represented by arithmetic mean for TTCA and CS2 concentration, geometric means (SD) of CS2 workers were 1.61 (1.91) mg/g.crea and 5.02 (1.84) ppm, respectively. There were no exposure-related differences in glucose metabolism or any of the endocrinological indices. CONCLUSIONS: No biologically significant effects of CS2 were found on endocrine function in Japanese rayon manufacturing workers when the average internal and external exposure levels were maintained below the current occupational exposure limit.     

Mesothelioma and lung tumors attributable to asbestos among petroleum workers

BACKGROUND: Asbestos exposure has been definitively found to be associated with both mesothelioma and lung cancer. Nevertheless, in the overall population of oil refinery workers potentially exposed to asbestos, many studies clearly show a definitely increased risk of mesothelioma, but no proven excess of lung cancer after comparison to the general population. Through the presentation of new data and the re-appraisal of two recent and independent epidemiological studies conducted in Liguria, Italy, and Ontario, Canada, we attempt to shed light on this apparently paradoxical finding. METHODS: Lung cancer mortality was studied among maintenance workers exposed to asbestos, and among two other subgroups of refinery employees: blue collar and white collar workers. The comparison with blue collar workers was performed in order to take into account the role of healthy worker effect, smoking habit, and the socioeconomic level. The comparison with white collar workers was performed to control for other occupational lung carcinogens. RESULTS AND CONCLUSIONS: Results reveal a consistency between the two studies and show that 96-100% of the mesotheliomas and 42-49% of the lung tumors arising among maintenance workers were attributable to asbestos exposure. Our new analysis, estimating two cases of asbestos-related lung cancer for each case of mesothelioma, confirms published findings on the magnitude of asbestos-related tumors in oil refineries.     

The morbidity and mortality of vermiculite miners and millers exposed to tremolite-actinolite: Part III. Radiographic findings

A study was conducted to estimate the exposure-response relationship for tremolite-actinolite fiber exposure and radiographic findings among 184 men employed at a Montana vermiculite mine and mill. Workers were included if they had been employed during 1975-1982 and had achieved at least 5 years tenure at the Montana site. Past fiber exposure was associated with an increased prevalence of parenchymal and pleural radiographic abnormalities. Smoking was not significantly related to the prevalence of small opacities. However, the number of workers who had never smoked was small, and this prevented measurement of the smoking effect. Under control for smoking and age, the prevalence of small opacities was significantly greater for vermiculite workers with greater than 100 fiber/cc-years exposure than for comparison groups (cement workers, blue collar workers, and coal miners) who had no known occupational fiber exposure. A logistic model predicted an increase of 1.3% in the odds ratio for small opacities at an additional exposure of 5 fiber-years.     

Effects of smoking and drinking on excretion of hippuric acid among toluene-exposed workers

Summary In order to investigate possible effects of smoking and drinking on the metabolism of toluence in occupational settings, 206 toluene-exposed men (mean age: 31.4 years) in shoemaking, painting, or surface-coating workshops together with 246 nonexposed control men (36.8 years) were studied for the time-weighted average intensities of exposure to toluene, hippuric acid concentration in shift-end urine samples, and the two social habits of smoking and drinking. The mean daily consumptions of cigarettes and ethanol were about 20 pieces and 10 g among smokers and drinkers, respectively. The geometric mean toluene concentration among the exposed subjects was about 20 ppm, with a maximum of 521 ppm. Regression analysis after classification of the subjects by smoking and drinking clearly demonstrated that the two social habits, when combined, markedly reduce the hippuric acid level in the urine of workers exposed to was a significant association between smoking and drinking habits, which hindered separate evaluation of the effects of the two habits on toluene metabolism. Comparison of the present results with the findings reported in the literature, however, suggested that the observed effects may be attributable to smoking rather than to drinking habits.