The confounding of occupation and smoking and its consequences

Low‑Level Environmental Heavy Metals are Associated with Obesity Among Postmenopausal Women in a Southern State

Both arsenic and cadmium are reported to be toxic to humans. The use of saliva as a biomarker of low-level exposures to these elements has not been adequately explored, and the putative relationship between exposure and obesity is unclear. This cross-sectional study aims to investigate the relationship between salivary arsenic and cadmium concentrations and their association with obesity. Arsenic and cadmium concentrations were analyzed in human saliva samples by Inductively Coupled Plasma-Mass Spectrometry on 270 randomly selected women who participated in the Arkansas Rural Community Health Study. Multivariable logistic regression was performed to evaluate the association between heavy metal concentrations and obesity. Stratified logistic regression was performed based on menopausal status. Generalized linear models were used to evaluate weight gain velocity. Significant positive associations were observed in postmenopausal women for both arsenic (OR = 4.43, 95% CI 1.91-10.28) and cadmium (OR = 2.72, 95% CI 1.23-5.99) concentrations, as well as significant trends among tertiles (p < 0.01 and p = 0.01, respectively). No relationship with obesity was evident among premenopausal women for either metal. A dose-response relationship was observed between increasing weight gain velocity and increasing metal concentrations. At concentrations well below governmental and industrial standards for acute toxicity, significant associations between obesity and concentration of these heavy metals are evident. The rate at which individuals gain weight is affected by metal concentrations and may play a role in the rapid increase in weight in postmenopausal women. These results might explain, in part, the missing variability in the increasing obesity pandemic in certain population exposed to these environmental toxicants.

Direct adjustment for confounding by smoking reduces radiation-related cancer risk estimates of mortality among male nuclear workers in Japan, 1999-2010

A causal relationship between protracted exposure to low-dose rate radiation and health effects remains unclear despite extensive international studies of nuclear workers. One potential reason is that radiation epidemiological studies that adjust for tobacco smoking, which heavily influences mortality, have been limited. In the present study, we examined radiation-related cancer risk by directly assessing the possible confounding effect of smoking, using data from two questionnaire surveys performed among Japanese nuclear workers in 1997 and 2003. Mortality follow-up was carried out for 71 733 male respondents for an average of 8.2 years during the observation period of 1999-2010. The mean cumulative dose was 25.5 mSv at the end of the follow-up period. Estimates of excess relative risk per Sv (ERRs/Sv) were obtained by Poisson regression. By adjusting for smoking directly on the basis of a linear dose-response model, we quantified the confounding effects of smoking on radiation risks. Statistically significant ERRs/Sv were found for all causes, all diseases, all non-cancer diseases, and liver cancer: 0.97 (90% confidence interval: 0.23, 1.78), 1.32 (0.40, 2.34), 1.87 (0.47, 3.49), and 4.78 (0.09, 11.68), respectively, without adjustment for smoking. However, the ERRs/Sv were no longer statistically significant after adjustment for smoking: 0.45 (-0.22, 1.19), 0.77 (-0.08, 1.72), 1.28 (-0.03, 2.79), and 3.89 (-0.46, 10.34), respectively. The ERRs/Sv for all cancers excluding leukaemia and lung cancer were not significant before adjustment for smoking, but declined after adjustment for smoking. The present study demonstrates that in this cohort of workers, smoking heavily distorts radiation risk estimates of mortality. The possibility of confounding by smoking depends on how strongly smoking is correlated with radiation exposure. If a correlation between smoking and radiation dose is suggested, smoking is an important confounder when assessing the radiation and health risks.

The behavioural constellation of deprivation: Causes and consequences

Socioeconomic differences in behaviour are pervasive and well documented, but their causes are not yet well understood. Here, we make the case that a cluster of behaviours is associated with lower socioeconomic status (SES), which we call “the behavioural constellation of deprivation.” We propose that the relatively limited control associated with lower SES curtails the extent to which people can expect to realise deferred rewards, leading to more present-oriented behaviour in a range of domains. We illustrate this idea using the specific factor of extrinsic mortality risk, an important factor in evolutionary theoretical models. We emphasise the idea that the present-oriented behaviours of the constellation are a contextually appropriate response to structural and ecological factors rather than a pathology or a failure of willpower. We highlight some principles from evolutionary theoretical models that can deepen our understanding of how socioeconomic inequalities can become amplified and embedded. These principles are that (1) small initial disparities can lead to larger eventual inequalities, (2) feedback loops can embed early-life circumstances, (3) constraints can breed further constraints, and (4) feedback loops can operate over generations. We discuss some of the mechanisms by which SES may influence behaviour. We then review how the contextually appropriate response perspective that we have outlined fits with other findings about control and temporal discounting. Finally, we discuss the implications of this interpretation for research and policy.

Knowledge of Occupational Chemical Exposure and Smoking Behavior in Korean Immigrant Drycleaners

To examine the association between knowledge of chemical exposure at work and cigarette smoking among Korean immigrant drycleaners. A cross-sectional survey was conducted with a total of 151 Korean immigrant drycleaners (mean age = 49 years, 64 % male) from 96 drycleaning shops in a Midwestern state. The data were collected on demographic and work-related characteristics, knowledge of occupational chemical exposure, health concerns associated with chemical exposure, and smoking status. Approximately 25 % of participants were current smokers. The multivariate regression showed that greater knowledge of occupational chemical exposures was significantly associated with a lower likelihood of current smoking [odds ratio (OR) .63; 95 % confidence interval (CI) .41-.95]. Furthermore, male gender (OR 6.32; 95 % CI 1.66-24.00), shorter-term residence in the US (OR .93; 95 % CI .88-.98), and having multiple duties (OR 2.76; 95 % CI 1.01-7.51) were important covariates associated with current smoking among Korean immigrant drycleaners. Knowledge on occupational chemical exposure was significantly associated with smoking among Korean immigrant drycleaners. Smoking cessation programs for this population should consider integrated approaches that incorporate work environment factors into individual and sociocultural components.

The association between occupational exposures and cigarette smoking among operating engineers

The purpose of this study was to determine the relationship between occupational exposures and cigarette smoking among operating engineers. A cross-sectional survey was conducted with operating engineers (N = 412) from a midwestern state in the United States. The survey included validated questions on cigarette smoking, occupational exposures, demographics, comorbidities, and health behaviors. About 35% were current smokers. Those exposed to asphalt fumes, heat stress, concrete dust, and welding fumes were less likely to smoke (odds ratio [OR] = .79, 95% confidence interval [CI]: .64-.98). Other factors associated with smoking included younger age (OR = .97, 95% CI: .94-.99), problem drinking (OR = 1.07, 95% CI: 1.03-1.12), lower Body Mass Index (OR = .95, 95% CI: .90-.99), and being separated/widowed/divorced (OR = 2.24, 95% CI: 1.19-4.20). Further investigation is needed for better understanding about job-specific exposure patterns and their impact on cigarette smoking among operating engineers.

Occupational Factors and Smoking Cessation among Unionized Building Trades Workers

The purpose of this study was to estimate the contribution of occupational factors to smoking cessation among building trades workers. Longitudinal data came from the MassBUILT smoking cessation intervention study for unionized building trades workers. Multivariable logistic regression analyses were applied to identify the significant predictors of smoking cessation, which was defined as abstinence from smoking during the previous 7 days at the 1-month monitoring and prolonged abstinence for at least 6 months at the 6-month monitoring. Greater concern about exposure to occupational hazards was significantly associated with increased likelihood of smoking cessation at 1 month (odds ratio = 1.06; 95% confidence interval = 1.01–1.11). Additionally, smokers who had a more positive view of their unions had at least marginally increased likelihood of smoking cessation at 1 month. Furthermore, older age, higher levels of educational attainment and household income, and fewer cigarettes smoked per day were important covariates that predicted smoking cessation. Concerns about exposures to work hazards should be incorporated into comprehensive intervention approaches for building trades workers. Additionally, the findings emphasize that blue-collar workers with lower income and education levels and heavy smokers should be considered target groups for implementing cessation interventions.

Cigarette smoking in building trades workers: the impact of work environment

BACKGROUND

Blue-collar workers smoke at higher rates than white-collar workers and the general population. Occupational factors may contribute to smoking behavior in this group. However, little is known about the role of occupational factors in explaining cigarette-smoking patterns.

METHODS

This study used cross-sectional data from the MassBUILT smoking cessation intervention study. Multivariable logistic regression analysis was conducted to investigate the association of occupational factors with current cigarette smoking among 1,817 building trades workers.

RESULTS

Current cigarette smoking was significantly associated with the following occupational factors: union commitment (OR = 1.06; 95% CI: 1.00-1.12); exposure to dust (OR = 1.50; 95% CI: 1.15-1.95), exposure to chemicals (OR = 1.41; 95% CI: 1.11-1.79); and concern about exposure to occupational hazards (OR = 0.93; 95% CI: 0.91-0.95).

CONCLUSION

The findings highlight the need to explicate the pathways by which occupational factors may contribute to current smoking behavior among building trades workers. Smoking cessation programs for this population should consider work-related occupational factors along with individual approaches.

Occupational status, work-site cessation programs and policies and menthol smoking on quitting behaviors of US smokers

AIM

This exploratory study sought to examine the relationships among occupational status, menthol smoking preference and employer-sponsored smoking cessation programs and policies on quitting behaviors.

DESIGN

Data for this cross-sectional study were obtained from the 2006 Tobacco Use Supplement to the Current Population Survey (TUS CPS), a large national survey representative of the civilian population, containing approximately 240,000 respondents. The total sample for the current study was 30,176.

MEASUREMENTS

The TUS CPS regularly collects data on cigarette prevalence, quitting behaviors, smoking history and consumption patterns. We performed a logistic regression with 'life-time quitting smoking for 1 day or longer because they were trying to quit' as outcome variable. Independent variables included type of occupation, employer-sponsored cessation programs and policies and menthol status.

FINDINGS

When controlling for occupational status and work-place policies, there were no differences for menthol versus non-menthol smokers on quitting behaviors [odds ratio (OR) = 0.98; 95% confidence interval (CI) = 0.83, 1.15]. Service workers were less likely to quit compared with white-collar workers (OR = 0.80; 95% CI = 0.69, 0.94), and those with no employer-sponsored cessation program were less likely to quit (OR = 0.70; 95% CI = 0.60, 0.83). White-collar workers, compared with blue-collar and service workers, were more likely to have a smoking policy in the work area (93% versus 86% versus 88%, respectively).

CONCLUSIONS

When occupational status and work-place smoking policies are controlled for, smokers of menthol cigarettes in the United States appear to have similar self-reported life-time rates of attempts to stop smoking to non-menthol smokers.

Socioeconomic Disparities in Health Behaviors

The inverse relationships between socioeconomic status (SES) and unhealthy behaviors such as tobacco use, physical inactivity, and poor nutrition have been well demonstrated empirically but encompass diverse underlying causal mechanisms. These mechanisms have special theoretical importance because disparities in health behaviors, unlike disparities in many other components of health, involve something more than the ability to use income to purchase good health. Based on a review of broad literatures in sociology, economics, and public health, we classify explanations of higher smoking, lower exercise, poorer diet, and excess weight among low-SES persons into nine broad groups that specify related but conceptually distinct mechanisms. The lack of clear support for any one explanation suggests that the literature on SES disparities in health and health behaviors can do more to design studies that better test for the importance of the varied mechanisms.

The association of workplace hazards and smoking in a U.S. multiethnic working-class population

OBJECTIVE

We investigated the extent to which smoking status was associated with exposure to occupational (e.g., dust, chemicals, noise, and ergonomic strain) and social (e.g., abuse, sexual harassment, and racial discrimination) workplace hazards in a sample of U.S. multiethnic working-class adults.

METHODS

United for Health is a cross-sectional study designed to investigate the combined burden of occupational and social workplace hazards in relation to race/ethnicity, gender, and wage and to evaluate related health effects in a working-class population. Using validated measures, we collected data from 1,282 multiethnic working-class participants using audio computer-assisted interviews. We used multiple imputation methods to impute data for those missing data. Crude and adjusted logistic odds ratios (ORs) were modeled to estimate ORs and 95% confidence intervals (CIs).

RESULTS

The prevalence of smoking was highest among non-Hispanic white workers (38.3%) and lowest for foreign-born workers (13.1%). We found an association between racial discrimination and smoking (OR = 1.12, 95% CI 1.01, 1.25). The relationship between smoking and sexual harassment, although not significant, was different for black women compared with men (OR = 1.79, 95% CI 0.99, 3.22). We did not find any associations by workplace abuse or by any of the occupational hazards.

CONCLUSION

These results indicate that racial discrimination might be related to smoking in working-class populations and should be considered in tobacco-control efforts that target this high-risk population.

MassBuilt: effectiveness of an apprenticeship site-based smoking cessation intervention for unionized building trades workers

Objective

Blue-collar workers are difficult to reach and less likely to successfully quit smoking. The objective of this study was to test a training site-based smoking cessation intervention.

Methods

This study is a randomized-controlled trial of a smoking cessation intervention that integrated occupational health concerns and was delivered in collaboration with unions to apprentices at 10 sites (n = 1,213). We evaluated smoking cessation at 1 and 6 months post-intervention.

Results

The baseline prevalence of smoking was 41%. We observed significantly higher quit rates in the intervention versus control group (26% vs. 16.8%; p = 0.014) 1 month after the intervention. However, the effects diminished over time so that the difference in quit rate was not significant at 6 month post-intervention (9% vs. 7.2%; p = 0.48). Intervention group members nevertheless reported a significant decrease in smoking intensity (OR = 3.13; 95% CI: 1.55–6.31) at 6 months post-intervention, compared to controls.

Conclusion

The study demonstrates the feasibility of delivering an intervention through union apprentice programs. Furthermore, the notably better 1-month quit rate results among intervention members and the greater decrease in smoking intensity among intervention members who continued to smoke underscore the need to develop strategies to help reduce relapse among blue-collar workers who quit smoking.

Difference in airflow obstruction between Hispanic and non-Hispanic White female smokers

Smoking-related respiratory diseases are a major cause of morbidity and mortality. However, the relationship between smoking and respiratory disease has not been well-studied among ethnic minorities in general and among women in particular. The objective of this cross-sectional study was to evaluate the risk of airflow obstruction and to assess lung function among Hispanic and non-Hispanic White (NHW) female smokers in a New Mexico cohort. Participants completed a questionnaire detailing smoking history and underwent spirometry testing. Outcomes studied included airflow obstruction, selected lung function parameters, and chronic mucus hyper-secretion. Chi square, logistic, and linear regression techniques were utilized. Of the 1,433 eligible women participants, 248 (17.3%) were Hispanic; and 319 had airflow obstruction (22.3%). Hispanic smokers were more likely to be current smokers, and report lower pack-years of smoking, compared to NHW smokers (p < 0.05 for all analyses). Further, Hispanic smokers were at a reduced risk of airflow obstruction compared to NHW smokers, with an O.R. of 0.51, 95% C.I. 0.34, 0.78 (p = 0.002) after adjustment for age, BMI, pack-years and duration of smoking, and current smoking status. Following adjustment for covariates, Hispanic smokers also had a higher mean absolute and percent predicted post-bronchodilator FEV(1)/FVC ratio, as well as higher mean percent predicted FEV(1) (p < 0.05 for all analyses). Hispanic female smokers in this New Mexico-based cohort had lower risk of airflow obstruction and better lung function than NHW female smokers. Further, smoking history did not completely explain these associations.

Using the National Health Interview Survey to understand and address the impact of tobacco in the United States: past perspectives and future considerations

OBJECTIVE

The National Health Interview Survey (NHIS) is a continuous, nationwide, household interview survey of the civilian noninstitutionalized population of the United States. This annual survey is conducted by the National Center for Health Statistics, part of the Centers for Disease Control and Prevention. Since 1965, the survey and its supplements have provided data on issues related to the use of cigarettes and other tobacco products. This paper describes the survey, provides an overview of peer-reviewed and government-issued research that uses tobacco-related data from the NHIS, and suggests additional areas for exploration and directions for future research.

DATA SOURCES

We performed literature searches using the PubMed database, selecting articles from 1966 to 2008. Study selection. Inclusion criteria were relevancy to tobacco research and primary use of NHIS data; 117 articles met these criteria. Data extraction and synthesis. Tobacco-related data from the NHIS have been used to analyze smoking prevalence and trends; attitudes, knowledge, and beliefs; initiation; cessation and advice to quit; health care practices; health consequences; secondhand smoke exposure; and use of smokeless tobacco. To date, use of these data has had broad application; however, great potential still exists for additional use.

CONCLUSION

NHIS data provide information that can be useful to both practitioners and researchers. It is important to explore new and creative ways to best use these data and to address the full range of salient tobacco-related topics. Doing so will better inform future tobacco control research and programs.

Being poor and coping with stress: health behaviors and the risk of death

OBJECTIVES

Individuals may cope with perceived stress through unhealthy but often pleasurable behaviors. We examined whether smoking, alcohol use, and physical inactivity moderate the relationship between perceived stress and the risk of death in the US population as a whole and across socioeconomic strata.

METHODS

Data were derived from the 1990 National Health Interview Survey's Health Promotion and Disease Prevention Supplement, which involved a representative sample of the adult US population (n = 40335) and was linked to prospective National Death Index mortality data through 1997. Gompertz hazard models were used to estimate the risk of death.

RESULTS

High baseline levels of former smoking and physical inactivity increased the impact of stress on mortality in the general population as well as among those of low socioeconomic status (SES), but not middle or high SES.

CONCLUSIONS

The combination of high stress levels and high levels of former smoking or physical inactivity is especially harmful among low-SES individuals. Stress, unhealthy behaviors, and low SES independently increase risk of death, and they combine to create a truly disadvantaged segment of the population.

Tobacco smoking by occupation in Australia and the United States: a review of national surveys conducted between 1970 and 2005

Tobacco use represents a key issue in workplace health, and much can be learned from countries where occupational smoking data has been regularly collected on a national basis. This article reviews national smoking surveys previously conducted in Australia and the United States between 1970 and 2005, and examines their relevance to the field of occupational tobacco control. When the first preliminary research was undertaken over 35 years ago, tobacco smoking was a regular feature in the general population of both countries, albeit with higher rates often documented among blue collar workers. Recent national investigations however, suggest that certain historical differences in smoking prevalence rates by occupation are persisting as we enter the 21st century. Detailed examination also indicates that employee sub-groups, such as cleaners and construction workers, are now bearing much of the occupational smoking burden in Australia and the United States. As such, there is an urgent need for more aggressive and finely targeted tobacco control activities in the workplace, as well as increased cooperation between tobacco control organizations, labor unions and other stakeholders, so that they may more effectively combat this ongoing threat to workers' health.

A decade of work on organized labor and tobacco control: reflections on research and coalition building in the United States

Labor unions can and should make strong allies in tobacco control efforts. Through much of the 1980s and 1990s, however, the organized labor and tobacco control communities rarely formed coalitions to achieve mutual gains. Recently, labor unions and tobacco control organizations have begun to work together on smoking cessation programs, smoke-free worksite policies, and increased insurance coverage for cessation treatments. This paper explores the historic and present-day intersections among organized labor and tobacco control advocates. We summarize research in this area and report on our recent programmatic efforts to promote collaboration between the labor and tobacco control communities. We discuss lessons learned with the aims of promoting deeper understanding among tobacco control and labor advocates of how each views tobacco control issues, and most importantly, stimulating further collaboration toward mutual gains in protecting workers' health.

Results of a union-based smoking cessation intervention for apprentice iron workers (United States)

OBJECTIVE

Blue-collar workers are more likely to smoke, smoke more heavily, and have less success in quitting compared to white-collar workers, and this occupational gap is growing over time. Effective smoking cessation interventions among blue-collar workers are needed to address growing class-based disparities.

METHODS

We used a pre-post study design to test feasibility and effect size of a smoking cessation trial in a union apprenticeship training program for iron workers (n = 337). The 4-month intervention drew upon a health promotion-health protection model for smoking cessation among blue-collar workers. We conducted pairwise analyses to assess pre-post intervention differences in 7-day point prevalence smoking abstinence measured 1 month after intervention was completed. Additional secondary outcomes, including smoking frequency, intensity, intention and self-efficacy to quit, were also assessed.

RESULTS

Baseline smoking prevalence was 41%. We observed a 19.4% post-intervention quit rate among baseline smokers. There were statistically significant positive changes pre- and post-intervention in intention to quit smoking, self-efficacy to quit, and a reduction in the number of days smoked. Participation in pro-active intervention components was associated with a three-fold (OR = 3.0, 1.15, 7.83) increase in the likelihood of quitting. Overall, participation in intervention components was low.

CONCLUSIONS

Labor union apprenticeship programs represent a promising venue for smoking cessation interventions, particularly those that draw upon a health promotion-health protection model.

Smoking, health, risk, and perception

We provide a description of health-related incentives faced by a rational smoker by considering the role of perception in both immediate quality-of-life effects of smoking and future risk of mortality. A person who adapts psychologically to a lowered health state, smokes more early in life and shifts demands for health investments and health-complementary activities later in life. He also smokes more in total. Someone aware of the full mortality consequences of smoking, smokes less and demands less medical care than someone who believes that these effects are highly reversible. The impacts of new information on mortality risk are most valuable early in life. Lastly, someone endowed with a longer life expectancy smokes more in the first part of life but conditional on access to medical care.

Socioeconomic status, smoking, and health: a test of competing theories of cumulative advantage

Although both low socioeconomic status and cigarette smoking increase health problems and mortality, their possible combined or interactive influence is less clear On one hand, the health of low status groups may be harmed least by unhealthy behavior such as smoking because, given the substantial health risks produced by limited resources, they have less to lose from damaging lifestyles. On the other hand, the health of low status groups may be harmed most by smoking because lifestyle choices exacerbate the health problems created by deprived material conditions. Alternatively, the harm of low status and smoking may accumulate additively rather than multiplicatively. We test these arguments with data from the 1990 U.S. National Health Interview Survey, and with measures of morbidity and mortality. For ascribed statuses such as gender, race, and ethnicity, and for the outcome measure of mortality, the results favor the additive argument, whereas for achieved status and morbidity, the results support the vulnerability hypothesis--that smoking inflicts greater harm among disadvantaged groups.

Reducing occupation-based disparities related to tobacco: roles for occupational health and organized labor

BACKGROUND

Persistent and growing occupation-based disparities related to tobacco pose a serious public health challenge. Tobacco exacts a disproportionate toll on individuals employed in working class occupations, due to higher prevalence of smoking and exposure to secondhand smoke among these workers compared to others.

METHODS

We provide an overview of recent advances that may help to reduce these disparities, including research findings on a successful social contextual intervention model that integrates smoking cessation and occupational health and safety, and a new national effort to link labor unions and tobacco control organizations around their shared interest in reducing tobacco's threat to workers' health.

CONCLUSIONS

Implications of these efforts for future research and action are discussed.

Working class matters: socioeconomic disadvantage, race/ethnicity, gender, and smoking in NHIS 2000

OBJECTIVES

We sought to describe the burden of smoking on the US population, using diverse socioeconomic measures.

METHODS

We analyzed data from the 2000 National Health Interview Survey.

RESULTS

Overall, the prevalence of current smoking was greatest among persons in--and independently associated with--working class jobs, low educational level, and low income. Attempts to quit showed no socioeconomic gradient, while success in quitting was greatest among those with the most socioeconomic resources. These patterns held in most but not all race/ethnicity-gender groups. Finer resolution of smoking patterns was obtained using a relational UK occupational measure, compared to the skill-based measure commonly used in US studies.

CONCLUSIONS

Reducing social disparities in smoking requires attention to the complexities of class along with race/ethnicity and gender.

Medium-sized business employees speak out about smoking

A health promotion study, funded by a state health department to meet objectives 3.4 and 3.11 of Healthy People 2000, was designed to: (1) identify tobacco use; (2) assess employees' beliefs on one's health and family member's health; and (3) assess the type of smoking policies favored. Using the Health Belief Model, it was hypothesized that there were differences in the health beliefs of tobacco users, former users, and never users. A 34-item questionnaire was administered to 1090 employees with a return rate of 603 (55%).

RESULTS

tobacco users perceived weight control and reduction of tension as benefits; they accepted warning label as hazardous but reported smokeless not as harmful; they perceived heart disease and cancer as related to tobacco use; and 62% had tried to quit smoking. Former and never users wanted "total ban policies" while, tobacco users wanted "designated areas" for smoking. All perceived their smoking and environmental tobacco smoke hazardous to their health and the health of family.

Use of multiple surveys to estimate mortality among never, current, and former smokers: changes over a 20-year interval

OBJECTIVES

This study sought to demonstrate how data from publicly available large-scale cross-sectional health surveys can be combined to analyze changes in mortality risks among never, current, and former smokers.

METHODS

Data from the 1966/68 and 1986 National Mortality Followback Surveys and the 1970 and 1987 National Health Interview Surveys were used to estimate the distribution of never, current, and former smokers among the US population at risk and decedents. Standardized mortality ratios and quotients of standardized mortality ratios were used to estimate mortality risks.

RESULTS

Generally, during the period from 1966 through 1986, mortality rates in the United States for most causes of death declined among all smoking groups. However, mortality rates from respiratory diseases increased for current and former smokers.

CONCLUSIONS

The reported changes in never and current smoker mortality risks are similar in magnitude and direction to those reported in a previous study based on longitudinal data. The use of combined data from the National Mortality Followback Survey and the National Health Interview Survey offers several advantages as an epidemiological tool.

An alternative explanation for the apparent elevated relative mortality and morbidity risks associated with exposure to environmental tobacco smoke

Insofar as industrial and other blue collar workers are more likely to bring home toxic materials on their person, and also are more likely to smoke than those in other occupations, members of a household are more likely to be subject to paraoccupational exposure and belong to lower socioeconomic strata if the household contains a smoker than if the household does not contain a smoker. Thus observed differences in risk of mortality or morbidity ascribed to ETS on the basis of a comparison of households with and without smokers may be partly or entirely due to differences in paraoccupational exposure and socioeconomic strata. Similarly, differences in mortality and morbidity ascribed to paraoccupational exposure may be partly or entirely due to differences in ETS exposure that are also related to social class and to types of occupation. Unfortunately, there are no data now in existence that could help determine separately the effects of these major confounded variables. There exists, then, a situation in which two explanations are advanced for respiratory diseases among members of a household, each based on similar study populations but focused on different major risk variables: ETS on the one hand, socioeconomic status and paraoccupational exposure on the other. Properly focused investigations need to be initiated.

Differences between smokers, ex-smokers, passive smokers and non-smokers

The extent to which current, ex- and passive smoking are associated with other risk factors, and the potential for confounding arising from these associations, was studied using a representative sample of 9003 British adults. The distribution of 33 lifestyle factors generally considered associated with adverse health were compared in current smokers, ex-smokers, never smokers living with a smoker ("passive smokers") and other never smokers. Of the 33 risk factors 27 showed a significantly higher prevalence in heavy smokers than in never smokers and only two showed a lower prevalence. For many risk factors, prevalence increased with amount smoked, decreased with time of smoking cessation and was increased in passive smokers. The possible magnitude of bias from confounding by the risk factors is estimated. It is concluded that confounding by multiple risk factors may be an important issue in smoking studies where weak associations are observed. This applies particularly to studies investigating the possible association of passive smoking with various health effects.

Environmental tobacco smoke and the risk of cancer in adults

The apparent effect of environmental tobacco smoke (ETS) exposure on cancer risk has become an important social and political issue. The risk of cancer in non-smokers is often the main reason for prohibiting or restricting smoking in public places. A number of epidemiological studies have shown an association between ETS exposure and lung cancer. However, the strength of this association has still to be estimated. Only a few studies have reported on ETS and cancer from sites other than the lung in adults. No definite conclusions can be drawn at present from a critical review of the epidemiological evidence, but the suggestion of an association is present for sinonasal cancer, while bladder cancer does not seem to be associated to ETS exposure. Positive studies are available for cancers from other sites, including the breast, the uterine cervix and the brain, but these are difficult to interpret.

Confounding of occupation and smoking: its magnitude and consequences

In a recent contribution to this journal, Sterling and Weinkam discuss the importance of the confounding of occupation and smoking when considering the contribution of smoking to mortality risk. In this report we provide estimates of the potential magnitude of this effect using data from a cohort study. It is shown that failing to consider possible confounding by socio-economic factors can lead to over-estimating of the strength of the relationship between smoking and mortality. The implications of these findings for the interpretation of results derived from observational studies are discussed.