Circulatory disease and smokeless tobacco in Western populations: a review of the evidence

Health effects associated with chewing tobacco: a Burden of Proof study

Chewing tobacco use poses serious health risks; yet it has not received as much attention as other tobacco-related products. This study synthesizes existing evidence regarding the health impacts of chewing tobacco while accounting for various sources of uncertainty. We conducted a systematic review and meta-analysis of chewing tobacco and seven health outcomes, drawing on 103 studies published from 1970 to 2023. We use a Burden of Proof meta-analysis to generate conservative risk estimates and find weak-to-moderate evidence that tobacco chewers have an increased risk of stroke, lip and oral cavity cancer, esophageal cancer, nasopharynx cancer, other pharynx cancer, and laryngeal cancer. We additionally find insufficient evidence of an association between chewing tobacco and ischemic heart disease. Our findings highlight a need for policy makers, researchers, and communities at risk to devote greater attention to chewing tobacco by both advancing tobacco control efforts and investing in strengthening the existing evidence base.

Tobacco harm reduction in Afghanistan: a recipe for improving smokers' health

Tobacco Harm Reduction (THR) offers a promising approach to addressing the significant burden of smoking in Afghanistan. Over three million Afghans smoke daily, making it a leading cause of preventable deaths in the country. While the previous Afghan government implemented various tobacco cessation policies and strategies, these measures were only partially effective in reducing the number of smokers or smoking-related deaths. In 2021, community-based initiatives in Kabul and Herat started advocating for Tobacco Harm Reduction (THR) as a novel, realistic, and practical approach proven to promote smoking abstinence and minimize tobacco harm. However, implementing THR strategies in Afghanistan faces numerous challenges, including a lack of governmental support, funding issues, unfavorable market conditions, the high cost-effectiveness of THR products, and misconceptions about these products. To effectively promote THR in Afghanistan and overcome these challenges, it will be necessary to implement THR policies that support THR products for smokers, regulate the market for these products, produce them locally with healthcare professional oversight, conduct more engaging advocacy campaigns, and secure domestic sponsors.

Update on new forms of tobacco use

Smoking remains the leading cause of morbidity and mortality worldwide. Because of its clear influence on cardiovascular and respiratory diseases, it is an important factor in internal medicine consultations. Although the rate of smoking cessation has been increasing in recent years, there is a percentage of patients who continue to smoke because they are unable or unwilling to quit, despite having tried existing pharmacological and non-pharmacological therapies. For this group of patients there are strategies based on interventions aimed at reducing the negative effects of smoking without the need for complete cessation. In this review it is shown that due to the absence of combustion of organic matter in conventional cigarettes, snus, e-cigarettes and heated tobacco products generate significantly lower levels of toxic substances.

'95% less harmful'? Exploring reactions to quantitative modified risk claims for snus and e-cigarettes

OBJECTIVES

Studies examining perceptions of 'modified risk tobacco product' (MRTP) messages for e-cigarettes and smokeless tobacco have indicated consumers want statistics and quantification of harm reduction. However, limited research exists on reactions to quantitative MRTP messages.

DESIGN

We conducted 12 focus groups in the USA in 2019-6 focused on e-cigarette messages and 6 on snus messages. Eight groups were with current smokers (ages 21-66) and four with young adult (ages 18-25) non-smokers (n=57). Participants discussed messages stating that use of snus and vaping products have been estimated by scientists to be about 90% and 95% less harmful than smoking cigarettes, respectively.

RESULTS

Several participants agreed the messages strongly communicated that the products are less harmful than cigarettes, were attention getting and could be 'convincing'. However, participants expressed scepticism about the source and accuracy of the stated figures, and some noted the claims could be misleading and attractive to young people. Comments also reflected some claim misunderstandings (eg, that e-cigarettes only pose a 5% chance of harm). Participants also agreed that stating e-cigarette risks 'are unlikely to exceed 5% of cigarette smoking harms' was confusing and less impactful than the '95% less harmful' wording.

CONCLUSIONS

Quantitative claims suggesting high levels of reduced risk when comparing e-cigarettes or smokeless tobacco/snus relative to cigarettes may be successful in gaining attention and being persuasive for some audiences, particularly, if from more credible sources. However, message developers, users and evaluators should be mindful of message limitations and aim to mitigate unintended consequences.

Smokeless Tobacco Use and Prevalence of Cardiovascular Disease Among Males in the Population Assessment of Tobacco and Health (PATH) Study, Waves 1–4

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Oral smokeless tobacco (SLT) products are non-combusted forms of tobacco that can be dependence producing.

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SLT use may pose health risks to users such as cardiovascular disease (CVD) through various pathways including influencing hemodynamics, endothelial dysfunction, inflammation, insulin resistance, hyperlipidemia, and arrhythmogenesis.

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Past studies have suggested a small, elevated risk of CVD among SLT users compared to never tobacco users.

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This study advances the literature by exploring how the duration of regular SLT use relates to CVD prevalence.

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In this study of ≥ 40-year-old men only, we did not find a consistent dose–response trend for years of SLT use and prevalence of CVD.

The purpose of this period prevalence study is to compare the prevalence of cardiovascular disease (CVD) in current/former established smokeless tobacco (SLT) users (ever SLT users who have used the product fairly regularly) to those who were: 1) never established cigarette smokers and SLT users, and 2) current/former established exclusive cigarette smokers (have smoked at least a 100 or more cigarettes in lifetime) only, adjusting for known risk factors for CVD. Analyses included 4,703 men ≥ 40 years of age who participated in the Population Assessment of Tobacco and Health (PATH) Study, Waves: 1–4, conducted between 2013 and 2017. Current users were those using SLT products daily or on some days, whereas former users had not used SLT and/or cigarettes in the past 12 months. CVD prevalence was defined as a self-reported diagnosis of congestive heart failure, stroke, or myocardial infarction. Among current/former established SLT users, years of use defined exposure history, while pack-years defined exposure history for smokers. Adjusted odds ratios (AOR) and 95% confidence intervals (CI) were reported with trend tests to examine dose–response associations. Current/former established exclusive SLT users were not significantly more likely to have had any CVD compared to never established cigarette and SLT users (OR = 1.7 [0.8–3.7]), or current/former established exclusive cigarette smokers (OR = 0.9 [0.5–1.8]). Current/former established exclusive cigarette smokers were more likely to have had any CVD compared to those who were never established cigarette and SLT users (OR = 1.6 [1.1–2.3]).

Tobacco harm reduction: Past history, current controversies and a proposed approach for the future

Tobacco harm reduction remains a controversial topic in tobacco control. Tobacco harm reduction involves providing tobacco users who are unwilling or unable to quit using nicotine products with less harmful nicotine-containing products for continued use. The skepticism towards harm reduction is based in part on the experience with low-yield tar/nicotine cigarettes, which were presumed to be associated with lower health risks than higher yield cigarettes and marketed as such by cigarette manufacturers. Only later did the field learn that these cigarettes were a deceptive way for cigarette manufacturers to allay the health concerns over cigarette smoking. Since this experience, there has been a proliferation of tobacco products that might potentially serve as a means to reduce tobacco harm. Some members of the tobacco control community believe that these products have great potential to reduce mortality and morbidity among smokers who completely switch to them. Others believe that we will be addicting another generation to tobacco products. This paper reviews the past history, the current tobacco landscape and controversies, and an approach that might rapidly reduce the yearly half-million deaths associated with cigarette smoking in the U.S.

Smokeless tobacco use and circulatory disease risk: a systematic review and meta-analysis

Objective

Smokeless tobacco use is a public health issue throughout the world, but reviews and analyses of circulatory disease risks associated with smokeless tobacco use may be outdated or incomplete. This study provides a thorough and comprehensive review and meta-analysis of circulatory disease risks in high-income countries, including recently published study estimates.

Methods

We conducted a systematic review of studies of circulatory disease risks associated with smokeless tobacco use in Europe and North America that were identified from electronic databases and reference lists. Study estimates were extracted by region, smokeless tobacco use status, cigarette smoking status, and circulatory condition and combined in meta-analysis using a random-effects model. We used the Newcastle-Ottawa scale to assess study quality and risk of bias.

Results

We identified 17 relevant cohort studies, two pooled analyses, five case-control studies and one cross-sectional analysis. We found increased risk of heart disease (relative risk (RR) 1.17, 95% CI 1.09 to 1.27) and stroke (RR 1.28, 95% CI 1.01 to 1.62) among US smokeless tobacco users compared with non-users. Increased circulatory disease risk was not observed among Swedish smokeless tobacco users.

Conclusion

US smokeless tobacco users were found to have increased risk of heart disease and stroke.

Improving the conduct of meta-analyses of observational studies

The author, who has published numerous meta-analyses of epidemiological studies, particularly on tobacco, comments on various aspects of their content. While such meta-analyses, even when well conducted, are more difficult to draw inferences from than are meta-analyses of clinical trials, they allow greater insight into an association than do simple qualitative reviews. This editorial starts with a discussion of some problems relating to hypothesis definition. These include the definition of the outcome, the exposure and the population to be considered, as well as the study inclusion and exclusion criteria. Under literature searching, the author argues against restriction to studies published in peer-reviewed journals, emphasising the fact that relevant data may be available from other sources. Problems of identifying studies and double counting are discussed, as are various issues in regard to data entry. The need to check published effect estimates is emphasised, and techniques to calculate estimates from material provided in the source publication are described. Once the data have been collected and an overall effect estimate obtained, tests for heterogeneity should be conducted in relation to different study characteristics. Though some meta-analysts recommend classifying studies by an overall index of study quality, the author prefers to separately investigate heterogeneity by those factors which contribute to the assessment of quality. Reasons why an association may not actually reflect a true causal relationship are also discussed, with the editorial describing techniques for investigating the relevance of confounding, and referring to problems resulting from misclassification of key variables. Misclassification of disease, exposure and confounding variables can all produce a spurious association, as can misclassification of the variable used to determine whether an individual can enter the study, and the author points to techniques to adjust for this. Issues relating to publication bias and the interpretation of “statistically significant” results are also discussed. The editorial should give the reader insight into the difficulties of producing a good meta-analysis.

Association between iq'mik smokeless tobacco use and cardiometabolic risk profile among Yup'ik Alaska Native people

OBJECTIVE

The traditional lifestyle of Yup'ik Alaska Native people, including a diet abundant in marine-based foods and physical activity, may be cardio-protective. However, iq'mik, a traditional form of smokeless tobacco used by >50% of Yup'ik adults, could increase cardiometabolic (CM) risk. Our objective was to characterize the associations between iq'mik use and biomarkers of CM status (low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], triglycerides [TG], systolic blood pressure [SBP] and diastolic blood pressure [DBP], glycated hemoglobin [HbA1c], fasting blood glucose [FBG], waist circumference [WC], and body mass index [BMI]).

DESIGN

We assessed these associations using data from a cross-sectional sample of Yup'ik adults (n = 874). Current iq'mik use, demographic, and lifestyle data were collected through interviews. Fasting blood samples were collected to measure LDL-C, HDL-C, TG, HbA1c, and FBG. SBP, DBP, WC, and BMI were obtained by physical examination. We characterized the association between current iq'mik use and continuous biomarkers of CM status using multiple approaches, including adjustment for measures of Yup'ik lifestyle and a propensity score.

RESULTS

Based on either adjustment method, current iq'mik use was significantly and positively associated with at least 5% higher HDL-C, and significantly associated but in an inverse direction with multiple biomarkers of CM status including 7% lower TG, 0.05% lower HbA1c, 2% lower FBG, 4% lower WC, and 4% lower BMI. Observed associations for LDL-C, SBP, and DBP varied by adjustment method.

CONCLUSIONS

This inverse association between iq'mik use and cardiometabolic risk status has not been previously reported. Additional research is needed to replicate these findings and explore physiological mechanisms and/or confounding factors.

Socio-demographic and behavioural determinants of body mass index among an adult population in rural Northern Ghana: the AWI-Gen study

BACKGROUND

Obesity and associated cardiometabolic diseases are increasing in urban sub-Saharan Africa due to a complex epidemiological and nutritional transition. Related data on rural communities is scarce.

OBJECTIVES

The study characterized the socio-demographic and behavioural factors influencing body mass index (BMI) among adults in rural Northern Ghana Methods: A population-based cross-sectional study involving adults aged 40-60 years residing in the Kassena-Nankana districts was undertaken. Demographic, socio-economic and behavioural data were collected along with measures of anthropometry. We determined factors associated with BMI among women and men.

RESULTS

A total of 2014 adults were studied. The median age was 51 (IQR 45-57) years and 54% were women. The prevalence of overweight/obesity was higher among women than men (18.4% vs. 7.2%; p < 0.001), whilst underweight was more prevalent in men (18.3% vs. 13.1%; p = 0.001). Participants with the highest level of education and a high household socio-economic status had higher BMIs than those in the lowest strata in both men (β = 0.074, p = 0.028 and β = 0.072, p < 0.001, respectively) and women (β = 0.174, p = 0.001 and β = 0.109, p < 0.001, respectively). Men (β = -0.050; p < 0.001) and women (β = -0.073; p < 0.001) of the Nankana ethnic group had a lower BMI than the Kassena ethnic group. Among men, alcohol consumption (β = -0.021; p = 0.001) and smoking (β = -0.216; p < 0.001) were associated with lower BMI. Smokeless tobacco was associated with lower BMI among women. Pesticide exposure was associated with higher BMI (β = 0.022; p = 0.022) among men.

CONCLUSION

Age, sex, ethno-linguistic group and prevailing socio-demographic and behavioural factors within this rural community in Northern Ghana influence BMI. The observed positive association between pesticide use and BMI warrants further investigation.

A longitudinal study of smokeless tobacco use and mortality in the United States

Few studies in the United States have examined longitudinally the mortality risks associated with use of smokeless tobacco (SLT). The sample of our study was composed of participants from the National Longitudinal Mortality Study who completed a single Tobacco Use Supplement to the Current Population Survey between the years 1985 and 2011. Using survival methods, SLT use at the baseline survey was examined as a predictor of all-cause mortality and cause-specific mortalities in models that excluded individuals who had ever smoked cigarettes, cigars or used pipes (final n = 349,282). The participants had median and maximum follow-up times of 8.8 and 26.3 years, respectively. Regression analyses indicated that compared to the never tobacco users, the current SLT users did not have elevated mortality risks from all cancers combined, the digestive system cancers and cerebrovascular disease. However, current SLT users had a higher mortality risk for coronary heart disease (CHD) [hazard ratio (HR) (95% CI) = 1.24 (1.05, 1.46)] relative to never tobacco users. In a separate model, the elevated risk for CHD mortality corresponded to the use of moist snuff [HR (95% CI) = 1.30 (1.03, 1.63)]. The associations with CHD mortality could be attributed to long-term nicotine exposure, other SLT constituents (e.g., metals) or the confounding effects of CHD risk factors not accounted for in our study. The study's findings contribute to the ongoing dialogue on tobacco harm reduction and the US FDA's evaluation of Modified Risk Tobacco Product applications submitted by American SLT manufacturers.

Use of Swedish smokeless tobacco (snus) and the risk of Type 2 diabetes and latent autoimmune diabetes of adulthood (LADA)

AIMS

It has been suggested that moist snuff (snus), a smokeless tobacco product that is high in nicotine and widespread in Scandinavia, increases the risk of Type 2 diabetes. Previous studies are however few, contradictory and, with regard to autoimmune diabetes, lacking. Our aim was to study the association between snus use and the risk of Type 2 diabetes and latent autoimmune diabetes of adulthood (LADA).

METHOD

Analyses were based on incident cases (Type 2 diabetes, n = 724; LADA, n = 200) and population-based controls (n = 699) from a Swedish case-control study. Additional analyses were performed on cross-sectional data from the Norwegian HUNT study (n = 21 473) with 829 prevalent cases of Type 2 diabetes. Odds ratios (OR) were estimated adjusted for age, BMI family history of diabetes and smoking. Only men were included.

RESULTS

No association between snus use and Type 2 diabetes or LADA was seen in the Swedish data. For Type 2 diabetes, the OR for > 10 box-years was 1.00 [95% confidence interval (CI), 0.47 to 2.11] and for LADA 1.01 (95% CI, 0.45 to 2.29). Similarly, in HUNT, the OR for Type 2 diabetes in ever-users was estimated at 0.91 (95% CI, 0.75 to 1.10) and in heavy users at 0.92 (95% CI, 0.46 to 1.83).

CONCLUSION

The risk of Type 2 diabetes and LADA is unrelated to the use of snus, despite its high nicotine content. This opens the possibility of the increased risk of Type 2 diabetes seen in smokers may not be attributed to nicotine, but to other substances in tobacco smoke.

Trends and Factors Related to Smokeless Tobacco Use in the United States

BACKGROUND

While declines in smoking prevalence in the United States have been well documented, trends in smokeless tobacco (SLT) use are less clear. This study updates previous analyses of US SLT use prevalence to better understand trends and factors related to SLT use.

METHODS

We used the Tobacco Use Supplement of the Current Population Survey (TUS-CPS) to examine trends and factors related to SLT use using joinpoint and logistic regression models. SLT consumption from 1985 to 2011 was obtained from the 2011 Federal Trade Commission Smokeless Tobacco Report. Sensitivity analyses were conducted for assessing the impact of varying frequency definitions of SLT use.

RESULTS

Decreasing trends in smoking and SLT prevalence overall were observed from 1992 to 2003 independently of use definition. SLT prevalence in the total adult population significantly decreased at an annual percent change (APC) of 4.5% per year from 1992 to 2003, but has been approximately constant ever since. Similar patterns were also found in adult males (APC = -4.4%) and young males (APC = -9.5%). SLT per capita consumption decreased significantly from 1991 to 1999 (APC = -2.2%), but has since decreased at only 0.35% per year (1999-2011). SLT use was found to be associated with former smoker status, younger age, white race, living in rural areas, residence in the South, lower education and unemployment, adjusting for other factors.

CONCLUSIONS

Declines in SLT use were found in the United States, suggesting tobacco control has had positive impacts, but these have slowed since 2003. Targeting tobacco control policies to at-risk demographic groups is needed to further reduce SLT use in the United States.

IMPLICATIONS

This study confirms that the declines in SLT use prevalence stopped in 2003 across different demographic groups, consistent with trends in SLT consumption. In addition, the longer period of analysis in comparison with earlier studies allows for quantitative characterization of SLT use trends using joinpoint regression. The study also shows the impact of different SLT use definitions in determining tobacco product use prevalence and trends.

Perceived Health Risks of Snus and Medicinal Nicotine Products

INTRODUCTION

Perceived health risk (PHR) of a tobacco product may influence both uptake and continued use. In this study, we examined PHRs of snus and medicinal nicotine using the PHR scale and the relationship of PHR responses to use of these products in smokers seeking an alternative to smoking.

METHODS

Smokers were randomly assigned to snus or to medicinal nicotine for a period of 12 weeks and asked to only use the assigned product. The PHR scale involves rating the extent of perceived risk of a product for different diseases and was given at baseline and weeks 4 and 12 during treatment. Relationships between PHR scale scores and study attrition, compliance with only using the product, and continued use of the product after treatment were determined.

RESULTS

Response to the PHR scale showed no significant differences between the snus and medicinal nicotine for perceived risks for lung cancer, emphysema, and bronchitis. However, significant differences were observed for other cancers, heart disease, stroke and risk for addiction, particularly after product use, with higher scores among those assigned to snus. Scores on the PHR scale were not related to any of the trial outcome variables.

CONCLUSIONS

Among smokers seeking an alternative to smoking in a clinic setting, PHR of a product changes after product use but may not be related to product use patterns.

IMPLICATIONS

PHRs of snus or medicinal nicotine in smokers assigned to these products become more accurate after product use. PHR does not appear to be associated with patterns of product use; rather satisfaction with a product is a better indicator as to whether a smoker is compliant with only using the product or continues to use the product.

Estimation of Nickel in Different Smokeless Tobacco Products and Their Impact on Human Health of Oral Cancer Patients

It has been extensively investigated that the chewing of smokeless tobacco (SLT) products may enhance the inflammation of the oral cavity. The aim of the present study is to evaluate the relationship between nickel (Ni) exposure via different SLT products with oral cancer (different sites) incidence in the population of Sindh, Pakistan. The different brands of SLT products (mainpuri, gutkha, and moist snuff) commonly consumed by the studied population were analyzed for Ni contents. The biological samples of oral cancer patients and noncancerous control subjects of both genders, who have or have not consumed SLT products, were collected. The concentration of Ni in biological samples and SLT products were measured by electrothermal atomic absorption spectrophotometer after microwave-assisted acid digestion. The validity and accuracy of the methodology were checked by using certified reference materials. The results of this study showed that the Ni level was significantly higher in scalp hair and blood samples of oral cancer patients compared to controls (P < 0.01). The study suggested that exposure of Ni as a result of chewing different SLT products may be synergistic with risk factors associated with oral cancer.

Associations of Proposed Relative-Risk Warning Labels for Snus With Perceptions and Behavioral Intentions Among Tobacco Users and Nonusers

INTRODUCTION

The US Food and Drug Administration can require changes in warning statements for modified risk tobacco products. We report an independent analysis of a consumer perception survey sponsored by Swedish Match as part of a Modified Risk Tobacco Product application to change warning labels for Swedish snus products.

METHODS

The survey exposed each of 4324 daily exclusive cigarette smokers, 1033 daily smokeless tobacco users, 1205 daily other tobacco users, 726 former users, and 5915 triers/never users to one of four current warnings and two proposed relative-risk labels (No tobacco product is safe, but this product presents lower risks to health than cigarettes, or No tobacco product is safe, but this product presents substantially lower risks to health than cigarettes) for snus. Descriptive and logistic regression analyses examined four outcomes: believability, harmfulness, motivation to use, and intention to buy snus.

RESULTS

Compared with the current not-safe-alternative warning, adult tobacco users who viewed the proposed labels perceived them as less believable, perceived snus as less harmful and were more likely to use and buy snus. The proposed labels had no impact on former smokers' likelihood to use and buy snus; triers/never users viewing the substantially lower risk label were more likely to buy snus.

CONCLUSIONS

Tobacco users viewing the proposed labels perceived snus as less harmful than cigarettes and may be more likely to use and buy snus. If labeling changes lead to increased snus use and cigarette reduction or abstinence, public health may benefit. If the opposite occurs, public health could suffer.

Nicotine: Pharmacology, Toxicity and Therapeutic use

Nicotine is naturally found in the plants belonging to the Solanaceae family. Concentrations high enough to have a pharmacological effect are seen only in the tobacco sub-family, approximately 2% of dry weight and in Duboisia Hopwoodii that has been used by Australian aborigines (http://en.wikipedia.org/wiki/Duboisia_hopwoodii). It is also present in the range of 2–7 microgram per kg of various edible plants.

Health risks related to dual use of cigarettes and snus - a systematic review

Reviews show that using snus (Swedish-type moist snuff) is much safer than smoking, with no increased risk from snus of cancer or circulatory disease yet demonstrated, but have not investigated possible health effects from dual use of cigarettes and snus. This review considers studies where health risks can be compared in dual users, those who only use snus or only smoke, and those who use neither product. The interaction RR, the ratio of RRs associated with snus use in smokers and in non-smokers, was used to test for special effects of dual use. Of 51 interaction RRs presented, only one (for gestational hypertension in a study based on the Swedish Medical Register) was significantly (p<0.05) above 1.0, and RRs below 1.0 were commoner, perhaps as cigarette consumption is lower in dual users than those who only smoke. Dual users more often initiate tobacco use with cigarettes than snus. Dual use is much commoner in adolescents than adults, possibly because many tobacco users try both products, eventually settling on one. Epidemiological evidence from various sources, though suffering from weaknesses, consistently suggests concomitant snus use increases smoking quit rates, and aligns with evidence from RCTs using snus to aid smoking cessation.

Association between betel quid chewing and carotid intima-media thickness in rural Bangladesh

BACKGROUND

Areca nut, more commonly known as betel nut, is the fourth most commonly used addictive substance in the world. Though recent evidence suggests it may play a role in the development of cardiovascular disease, no studies have investigated whether betel nut use is related to subclinical atherosclerosis.

METHODS

We evaluated the association between betel nut use and subclinical atherosclerosis in 1206 participants randomly sampled from the Health Effects of Arsenic Longitudinal Study (HEALS). Frequency and duration of betel nut use were assessed at baseline, and carotid IMT was measured on average 6.65 years after baseline.

RESULTS

A positive association was observed between duration and cumulative exposure (function of duration and frequency) of betel nut use and IMT, with above-median use for duration (7 or more years) and cumulative exposure (30 or more quid-years) corresponding to a 19.1 μm [95% confidence interval (CI): 5.3-32.8; P ≤ 0.01] and 16.8 μm (95% CI: 2.9-30.8; P < 0.05) higher IMT in an adjusted model, respectively. This association was more pronounced in men [32.8 μm (95% CI: 10.0-55.7) and 30.9 μm (95% CI: 7.4-54.2)]. There was a synergy between cigarette smoking and above-median betel use such that the joint exposure was associated with a 42.4 μm (95% CI: 21.6-63.2; P ≤ 0.01) difference in IMT.

CONCLUSION

Betel nut use at long duration or high cumulative exposure levels is associated with subclinical atherosclerosis as manifested through carotid IMT. This effect is especially pronounced among men and cigarette smokers.

Epidemiological evidence relating snus to health--an updated review based on recent publications

An earlier review summarized evidence relating use of snus (Swedish-type moist snuff) to health and to initiation and cessation of smoking. This update considers the effect recent publications on snus use and health have on the overall evidence. The additional evidence extends the list of neoplastic conditions unassociated with snus use (oropharynx, oesophagus, stomach, lung) to include colorectal cancer and acoustic neuroma, and further undermines the weakly-based argument that snus use increases the risk of pancreatic cancer, although there is a report of poorer cancer survival in users. It remains undemonstrated that “snuff-dipper’s lesion” increases risk of oral cancer, and recent publications add to the evidence that snus use has no effect on periodontitis or dental caries. Although onset of acute myocardial infarction is not adversely associated with snus use, there is some evidence of an association with reduced survival. Whether this is a direct effect of snus use or a result of confounding by socioeconomic status or other factors requires further investigation, as does a report of an increased risk of heart failure in snus users. Even if some adverse health effects of snus use do exist, it remains clear that they are far less than those of smoking.

The effect on health of switching from cigarettes to snus - a review

Interest in snus (Swedish type moist snuff) as an alternative to smoking is increasing, but the evidence on the health effects of switching from cigarettes to snus has not previously been reviewed. We identified six epidemiological cohort or case-control studies, all from Sweden, which allowed comparison of cancer or cardiovascular disease risk in current snus users who formerly smoked ("switchers") with that of never snus users who continued to smoke ("continuers") or of never snus users who quit smoking ("quitters"). Based on 13 sets of comparisons, one for oral cancer, one for stomach cancer and 11 for various cardiovascular disease endpoints, switchers were consistently found to have a lower risk than continuers, with relative risks varying from 0.35 to 0.61, and a similar risk to quitters. Based on estimates from four studies for ischaemic/coronary heart disease or acute myocardial infarction, meta-analyses gave combined relative risk estimates of 0.55 (95% confidence interval 0.45-0.68) for switchers vs. continuers and 1.02 (95% confidence interval 0.83-1.26) for switchers vs. quitters. Though based on limited evidence with some weaknesses, these results are consistent with a recent review which found no increased risk of cancer or heart disease from snus use.

Use of snus and acute myocardial infarction: pooled analysis of eight prospective observational studies

The use of snus (also referred to as Scandinavian or Swedish moist smokeless tobacco), which is common in Sweden and increasing elsewhere, is receiving increasing attention since considered a tobacco smoke "potential reduction exposure product". Snus delivers a high dose of nicotine with possible hemodynamic effects, but its impact on cardiovascular morbidity and mortality is uncertain. The aim of this study was to investigate whether snus use is associated with risk of and survival after acute myocardial infarction (AMI). Data from eight prospective cohort studies set in Sweden was pooled and reanalysed. The relative risk of first time AMI and 28-day case-fatality was calculated for 130,361 men who never smoked. During 2,262,333 person-years of follow-up, 3,390 incident events of AMI were identified. Current snus use was not associated with risk of AMI (pooled multivariable hazard ratio 1.04, 95 % confidence interval 0.93 to 1.17). The short-term case fatality rate appeared increased in snus users (odds ratio 1.28, 95 % confidence interval 0.99 to 1.68). This study does not support any association between use of snus and development of AMI. Hence, toxic components other than nicotine appear implicated in the pathophysiology of smoking related ischemic heart disease. Case fatality after AMI is seemingly increased among snus users, but this relationship may be due to confounding by socioeconomic or life style factors.

Effects of a Fact Sheet on beliefs about the harmfulness of alternative nicotine delivery systems compared with cigarettes

BACKGROUND

This study explored the value of providing information in a Fact Sheet to correct misperceptions about the relative harmfulness of nicotine replacement products (NRT) and smokeless tobacco (ST), when compared to cigarette smoking.

METHODS

Four convenience samples from different countries (Australia, UK, Sweden and USA) were surveyed concerning their beliefs about the relative harmfulness of smokeless tobacco and NRT. Study participants were given the Fact Sheet that explained that nicotine, as used by consumers, is not particularly harmful and explained why. They were resurveyed one week later regarding their beliefs about the relative harmfulness of smokeless tobacco and NRT and future intentions to use the products.

RESULTS

In all four samples knowledge increased by similar amounts and beliefs regarding the lower harmfulness of smokeless tobacco increased. However, misconceptions remained common and responses to belief measures were not always consistent. Likelihood of use of ST increased in all four samples after exposure to the Fact Sheet, but interest in NRT use only increased in the US sample.

CONCLUSIONS

A Fact Sheet such as this one can help address misconceptions about NRT and smokeless tobacco, at least in the short term. However, as is true of most educational interventions, exposure to a single educational session is not sufficient to overcome misperceptions that smokers have about the relative harmfulness of oral versus combustible forms of nicotine delivery.

Who is using snus? - Time trends, socioeconomic and geographic characteristics of snus users in the ageing Swedish population

BACKGROUND

The prevalence of smoking in Sweden has decreased in recent decades, and is now among the lowest in the world. During the same period, the use of Swedish moist oral snuff, a smokeless tobacco called snus, has increased. Few studies have evaluated time trends of the socioeconomic and geographic characteristics of snus users in Sweden. This paper contributes to filling that gap.

METHODS

This study utilized the Linnaeus Database, which links national registers with comprehensive individual data on socioeconomic status (SES) to health data from a large ongoing health survey, the Västerbotten Intervention Programme (VIP). The VIP targets the entire middle-aged population of Västerbotten county at ages 40, 50 and 60 years with yearly cross-sectional surveys including self-reported data on tobacco habits. Time trends of snus use among 92,563 VIP-participants across different areas of residence and smoking groups were investigated graphically. Logistic regression was performed to estimate the associations between SES and geographical variables and current use versus non-use of snus.

RESULTS

Overall, in parallel to decreasing smoking, the increasing trend of snus use in this middle-aged population continues, particularly in 40-year-olds. In both genders, the highest prevalence of snus use was observed among previous smokers. The prevalence of snus use also increased over time among smokers, and was consistently higher compared to those who had never smoked. Among males - both those who had never smoked and previous smokers - low education (OR 1.21, 95%CI 1.06-1.40 and OR 1.28, 95%CI 1.14-1.43), living alone (OR 1.16, 95%CI 1.07-1.27 and OR 1.13, 95%ci 1.04-1.23), low income and living in rural areas was associated with using snus, while this was not seen among male current smokers. Among women, living alone was associated with using snus irrespective of smoking habits. Among female smokers, the OR for snus use increased with higher education.

CONCLUSIONS

A disadvantaged social profile and also higher prevalence in rural areas is observed among male snus users who had never smoked or were previous smokers. Among male smokers there was no association between SES and use of snus. The prevalence of snus use among women is increasing, but is still considerably lower than that of men. The association between snus and SES characteristics is less pronounced among women, although snus is clearly linked to living alone. These patterns should be taken into consideration in tobacco control policies.

The scientific foundation for tobacco harm reduction, 2006-2011

Over the past five years there has been exponential expansion of interest in tobacco harm reduction (THR), with a concomitant increase in the number of published studies. The purpose of this manuscript is to review and analyze influential contributions to the scientific and medical literature relating to THR, and to discuss issues that continue to stimulate debate. Numerous epidemiologic studies and subsequent meta-analyses confirm that smokeless tobacco (ST) use is associated with minimal risks for cancer and for myocardial infarction; a small increased risk for stroke cannot be excluded. Studies from Sweden document that ST use is not associated with benign gastrointestinal disorders and chronic inflammatory diseases. Although any form of nicotine should be avoided during pregnancy, the highest risks for the developing baby are associated with smoking. It is documented that ST use has been a key factor in the declining rates of smoking and of smoking-related diseases in Sweden and Norway. For other countries, the potential population health benefits of ST are far greater than the potential risks. In follow-up studies, dual users of cigarettes and ST are less likely than exclusive smokers to achieve complete tobacco abstinence, but they are also less likely to be smoking. The health risks from dual use are probably lower than those from exclusive smoking. E-cigarette users are not exposed to the many toxicants, carcinogens and abundant free radicals formed when tobacco is burned. Although laboratory studies have detected trace concentrations of some contaminants, it is a small problem amenable to improvements in quality control and manufacturing that are likely with FDA regulation as tobacco products. There is limited evidence from clinical trials that e-cigarettes deliver only small doses of nicotine compared with conventional cigarettes. However, e-cigarette use emulates successfully the cigarette handling rituals and cues of cigarette smoking, which produces suppression of craving and withdrawal that is not entirely attributable to nicotine delivery. THR has been described as having "the potential to lead to one of the greatest public health breakthroughs in human history by fundamentally changing the forecast of a billion cigarette-caused deaths this century."

The association between active smoking, smokeless tobacco, second-hand smoke exposure and insufficient sleep

BACKGROUND

Studies have shown that cigarette smoking is associated with sleep disorders in the general population. But studies examining the association between smokeless tobacco use, second-hand smoke exposure and insufficient rest/sleep are limited.

METHODS

We examined the association between smoking, smokeless tobacco use (n=83,072), second-hand smoke exposure (n=28,557) and insufficient rest/sleep among adults aged ≥20 years in the state-based 2008 Behavioral Risk Factor Surveillance System. Exposure to second-hand smoke was defined as >1 day of exposure to cigarette smoking either at home or in the workplace in the preceding 7 days. Insufficient rest/sleep was defined as not getting enough rest/sleep everyday in the preceding 30 days.

RESULTS

Compared to never smokeless tobacco users, the odds ratio (OR; 95% confidence interval [CI]) of insufficient rest/sleep was 1.16 (1.00-1.36) and 1.74 (1.37-2.22) among former and current users. Compared to non-smokers/non-smokeless tobacco users, the OR (95% CI) of insufficient rest/sleep for those who were both current smokers and current smokeless tobacco users was 2.21 (1.66-2.94). Regarding second-hand smoke exposure among non-smokers, those with second-hand smoke exposure had higher odds for insufficient rest/sleep than those without. In contrast, the odds of insufficient rest/sleep were similar among current smokers with or without second-hand smoke exposure.

CONCLUSIONS

In a multiethnic sample of US adults, compared to non-smokers/non-smokeless tobacco users, those who were both current smokers and current smokeless tobacco users had twice the odds of insufficient sleep. Second-hand smoke exposure was associated with insufficient rest/sleep among non-smokers.

Summary of the epidemiological evidence relating snus to health

Interest in snus (Swedish-type moist snuff) as a smoking alternative has increased. This wide-ranging review summarizes evidence relating snus to health and to initiation and cessation of smoking. Meta-analyses are included. After smoking adjustment, snus is unassociated with cancer of the oropharynx (meta-analysis RR 0.97, 95% CI 0.68-1.37), oesophagus (1.10, 0.92-1.33), stomach (0.98, 0.82-1.17), pancreas (1.20, 0.66-2.20), lung (0.71, 0.66-0.76) or other sites, or with heart disease (1.01, 0.91-1.12) or stroke (1.05, 0.95-1.15). No clear associations are evident in never smokers, any possible risk from snus being much less than from smoking. "Snuff-dipper's lesion" does not predict oral cancer. Snus users have increased weight, but diabetes and chronic hypertension seem unaffected. Notwithstanding unconfirmed reports of associations with reduced birthweight, and some other conditions, the evidence provides scant support for any major adverse health effect of snus. Although some claims that snus reduces initiation or encourages quitting are unsoundly based, snus seems not to increase initiation, as indicated by few smokers using snus before starting and current snus use being unassociated with smoking in adults (the association in children probably being due to uncontrolled confounding), and there are no reports that snus discourages quitting.

Socio-demographic, lifestyle and health characteristics among snus users and dual tobacco users in Stockholm County, Sweden

BACKGROUND

Socio-demographic and lifestyle characteristics of snus users have not been systematically described. Such knowledge is pivotal for tobacco control efforts and for the assessment of health effects of snus use.

METHODS

A cross-sectional study was conducted, based on the Stockholm Public Health Survey, including a population-based sample of 34,707 men and women aged 18-84 years. We examined how socio-demographic, lifestyle and health-related characteristics were associated with the prevalence of current daily snus use, smoking and dual tobacco use. Logistic regression was used to calculate odds ratios of prevalence (ORs) and 95% confidence intervals (CIs).

RESULTS

Low educational level (OR = 1.60, CI = 1.41-1.81 and OR = 1.49, CI = 1.17-1.89, for men and women respectively), as well as occupational class and low income were associated with snus use. Some unfavourable lifestyle characteristics, including risky alcohol consumption (males: OR = 1.81, CI = 1.63-2.02; females: OR = 1.79, CI = 1.45-2.20), binge drinking and low consumption of fruit and vegetables were also associated with snus use. In contrast, physical inactivity and overweight/obesity were not, nor was perceived health. The prevalence of smoking followed steeper gradients for social as well as lifestyle characteristics. Overweight and obese men were however less often smokers. Perceived poor general health and psychological distress were highly related to smoking. Social disadvantage, as well as unhealthy lifestyle and self-reported poor health were strongly associated with dual use. There were limited differences between men and women.

CONCLUSIONS

The social, lifestyle and health profiles of exclusive snus users in Stockholm County are less favourable than those of non-users of tobacco, but more advantageous than those of exclusive smokers. This knowledge should guide tobacco control measures as well as the interpretation of health risks linked to snus use.

Does dual use jeopardize the potential role of smokeless tobacco in harm reduction?

INTRODUCTION

The use of smokeless tobacco as part of a strategy to reduce the harm from cigarette smoking is a topic of debate within the tobacco control and public health communities. One concern voiced regarding endorsement of such a tactic is the possibility of actually increasing harm should current smokers adopt dual cigarette/smokeless tobacco use (dual use), which could lead to unintended consequences by perpetuating cigarette smoking, diminishing tobacco cessation, or increasing tobacco-related harm.

METHODS

Here, we review the available literature on health effects and trajectories of use among dual users from a variety of U.S. and European epidemiological studies.

RESULTS

These data suggest that there are not any unique health risks associated with dual use of smokeless tobacco products and cigarettes, which are not anticipated or observed from cigarette smoking alone. Furthermore, studies show that dual users smoke fewer cigarettes than exclusive smokers, and studies of tobacco use patterns over time (tobacco use trajectory data) indicate that dual users are more likely than exclusive cigarette smokers to cease smoking.

CONCLUSIONS

Overall, the concern about dual use appears to be contradicted by the evidence in the literature that dual use of smokeless tobacco and cigarettes may result in reduction in smoking-related harm as smoking intensity is decreased and smoking cessation increases.

Risk of incident cardiovascular disease among users of smokeless tobacco in the Atherosclerosis Risk in Communities (ARIC) study

Use of smokeless tobacco in the United States has been relatively constant in recent years, as tobacco companies continue aggressive marketing campaigns. The health effects of smokeless tobacco use need further documentation. Thus, the authors examined whether current use of smokeless tobacco was associated with increased incidence of cardiovascular disease (CVD) in 14,498 men and women aged 45-64 years at baseline (1987-1989) in the Atherosclerosis Risk in Communities (ARIC) Study. There were 2,572 incident CVD events (myocardial infarction, coronary revascularization, coronary death, or stroke) during a median of 16.7 years of follow-up (maximum = 19.1 years). Current use of smokeless tobacco at baseline was associated with 1.27-fold greater CVD incidence (95% confidence interval: 1.06, 1.52) than was nonuse, independently of demographic, socioeconomic, and lifestyle and other tobacco-related variables. Past use of smokeless tobacco was not associated with CVD incidence. In conclusion, current use of smokeless tobacco was associated with increased risk of CVD incidence in ARIC cigarette nonsmokers. Current users of smokeless tobacco should be informed of its harm and advised to quit the practice. Current cigarette smokers should also be given sufficient information on safe, therapeutic methods of quitting which do not include switching to smokeless tobacco.

Smokeless tobacco: a gateway to smoking or a way away from smoking

Recently, tobacco companies have been marketing moist smokeless tobacco products that are 'spitless'. These products have lower concentrations of tobacco-specific nitrosamines and of other harmful chemicals than other tobacco products, but can deliver relatively high doses of nicotine. They are packaged in small sachets, similar to tea bags that are placed between cheek and gum. Global promotion of smokeless tobacco products is hotly debated among tobacco control and public health experts. Proponents point to the Swedish experience where snus (Swedish moist snuff) is widely used as an alternative to cigarette smoking among men. Meanwhile, Sweden has low rates of smoking and a lower rate of respiratory diseases and lung cancers by comparison to other developed countries. The opponents argue that snus has its own risks, that no form of tobacco should ever be promoted; and that 'snus is culture-bound and not transferable to other settings'. Critics also suspect that the tobacco industry will use snus marketing as a 'gateway' to promote cigarettes among young people. Research on the effects of marketing snus to smokers is too limited to support using snus as a harm-reduction tool, and the epidemiological data are not conclusive.

Evaluation of cadmium and zinc in biological samples of tobacco and alcohol user male mouth cancer patients

There is compelling evidence in support of positive associations between zinc (Zn) deficiency and high accumulation of cadmium (Cd) in biological samples of different cancerous patients. The incidence of mouth cancer has been increased among people who possess habit of drinking alcohol, tobacco smoking and chewing with gradients in Pakistan. In the present study, Cd and Zn contents of blood and scalp hair samples of 92 male mouth cancer patients and 78 referents of same age group (range 35-65 years), socio-economic status, localities and dietary habits. Among referent male subjects, 56 consumed tobacco (smoking/chewing), 22 had none of smoking and chewing tobacco habits, while none of them admitted for alcohol drinking. The scalp hair and whole blood samples were oxidized by 65% nitric acid and 30% hydrogen peroxide (2:1) ratio in microwave oven. The Zn in digests was determined by flame atomic absorption while Cd was determined by electrothermal atomic absorption spectrometry. The average Cd concentration was higher, while level of Zn was lower in the blood and scalp hair samples of mouth cancer patients as compared to referent subjects (p < .001). The male referents consuming tobacco (chewing and smoking) have high level of Cd in both their biological samples as compared to those not smoking or chewing tobacco (p < .012). The Cd/Zn ratio in both biological samples was found to be higher in patients than in referent subjects.

Use of smokeless tobacco and risk of myocardial infarction and stroke: systematic review with meta-analysis

OBJECTIVE

To assess whether people who use smokeless tobacco products are at increased risk of myocardial infarction and stroke.

DESIGN

Meta-analysis of observational studies from Sweden and the United States.

DATA SOURCES

Electronic databases and reference lists.

DATA EXTRACTION

Quantitative estimates of the association between use of smokeless tobacco products and risk of myocardial infarction and stroke among never smokers.

REVIEW METHODS

Both authors independently abstracted risk estimates and study characteristics. Summary relative risks were estimated on the basis of random effects models.

RESULTS

11 studies, mainly in men, were included. Eight risk estimates were available for fatal myocardial infarction: the relative risk for ever use of smokeless tobacco products was 1.13 (95% confidence 1.06 to 1.21) and the excess risk was restricted to current users. The relative risk of fatal stroke, on the basis of five risk estimates, was 1.40 (1.28 to 1.54). The studies from both the United States and Sweden showed an increased risk of death from myocardial infarction and stroke. The inclusion of non-fatal myocardial infarction and non-fatal stroke lowered the summary risk estimates. Data on dose-response were limited but did not suggest a strong relation between risk of dying from either disease and frequency or duration of use of smokeless tobacco products.

CONCLUSION

An association was detected between use of smokeless tobacco products and risk of fatal myocardial infarction and stroke, which does not seem to be explained by chance.

Systematic review of the relation between smokeless tobacco and cancer in Europe and North America

BACKGROUND

Interest is rising in smokeless tobacco as a safer alternative to smoking, but published reviews on smokeless tobacco and cancer are limited. We review North American and European studies and compare effects of smokeless tobacco and smoking.

METHODS

We obtained papers from MEDLINE searches, published reviews and secondary references describing epidemiological cohort and case-control studies relating any form of cancer to smokeless tobacco use. For each study, details were abstracted on design, smokeless tobacco exposure, cancers studied, analysis methods and adjustment for smoking and other factors. For each cancer, relative risks or odds ratios with 95% confidence intervals were tabulated. Overall, and also for USA and Scandinavia separately, meta-analyses were conducted using all available estimates, smoking-adjusted estimates, or estimates for never smokers. For seven cancers, smoking-attributable deaths in US men in 2005 were compared with deaths attributable to introducing smokeless tobacco into a population of never-smoking men.

RESULTS

Eighty-nine studies were identified; 62 US and 18 Scandinavian. Forty-six (52%) controlled for smoking. Random-effects meta-analysis estimates for most sites showed little association. Smoking-adjusted estimates were only significant for oropharyngeal cancer (1.36, CI 1.04-1.77, n = 19) and prostate cancer (1.29, 1.07-1.55, n = 4). The oropharyngeal association disappeared for estimates published since 1990 (1.00, 0.83-1.20, n = 14), for Scandinavia (0.97, 0.68-1.37, n = 7), and for alcohol-adjusted estimates (1.07, 0.84-1.37, n = 10). Any effect of current US products or Scandinavian snuff seems very limited. The prostate cancer data are inadequate for a clear conclusion.Some meta-analyses suggest a possible effect for oesophagus, pancreas, larynx and kidney cancer, but other cancers show no effect of smokeless tobacco. Any possible effects are not evident in Scandinavia. Of 142,205 smoking-related male US cancer deaths in 2005, 104,737 are smoking-attributable. Smokeless tobacco-attributable deaths would be 1,102 (1.1%) if as many used smokeless tobacco as had smoked, and 2,081 (2.0%) if everyone used smokeless tobacco.

CONCLUSION

An increased risk of oropharyngeal cancer is evident most clearly for past smokeless tobacco use in the USA, but not for Scandinavian snuff. Effects of smokeless tobacco use on other cancers are not clearly demonstrated. Risk from modern products is much less than for smoking.

Cigarette smoking, smoking cessation, and diabetes

There is evidence for increased risk of developing type 2 diabetes among cigarette smokers. In addition, smoking-associated health risks can exacerbate major conditions that precede or accompany diabetes, such as cardiovascular and kidney diseases. Smoking cessation can result in weight gain and a short-term worsening of some diabetic symptoms that may deter smokers with diabetes from attempting to quit. Additionally, there is limited evidence regarding the efficacy/safety of smoking cessation pharmacotherapies in this population and the general effects of smoking cessation, particularly for type 1 diabetes. Smoking cessation in diabetes therefore remains a highly relevant subject for further research.

Use of snus and risk for cardiovascular disease: results from the Swedish Twin Registry

OBJECTIVE

To study the association between snus use and the risk for cardiovascular disease, i.e. ischemic heart disease and stroke.

DESIGN

Cohort study.

SETTING

Sweden.

SUBJECTS

Sixteen thousand six hundred and forty-two male Swedish twins participating in the Screening Across the Lifespan Twin Study, conducted in 1998- 2002, were followed for incident cardiovascular disease. Participants were without a history of cardiovascular disease at baseline and incident cases were identified via the Swedish Cause of Death Register and Hospital Discharge Register.

RESULTS

Overall, there was no association between use of snus and risk for cardiovascular disease. Current snus users, without a smoking history, had a relative risk of 1.00 (95% confidence interval 0.69-1.46) for cardiovascular disease as compared to non users. Corresponding relative risks for ischemic heart disease and stroke were 0.85 (95% confidence interval 0.51-1.41) and 1.18 (95% confidence interval 0.67-2.08), respectively. In smoking adjusted models, risk estimates for ischemic heart disease in relation to snus use were all close to unity regardless of timing or intensity of snus use. However, current heavy snus users (consuming more than four cans week(-1)) had a relative risk for stroke of 1.75 (95% confidence interval 0.95-3.21).

CONCLUSION

These data do not support any strong association between snus use and risk for cardiovascular disease.

Swedish snuff and incidence of cardiovascular disease. A population-based cohort study

Background

The relationship between smoking and an increased incidence of cardiovascular diseases is well known. Whether smokeless tobacco (snuff) is related to myocardial infarction (MI) or stroke is still controversial. Aim of this study was to explore whether snuff users have an increased incidence of MI or stroke.

Methods

A total of 16 754 women and 10 473 men (aged 45–73 years), without history of cardiovascular disease (CVD), belonging to the population-based "Malmö Diet and Cancer" study were examined. Incidence of MI and stroke were monitored over 10.3 years.

Results

Snuff was used by 737 (7.0%) men and 75 (0.4%) women, respectively. Among men, snuff was significantly associated with low occupation level, single civil status, high BMI and with current and former smoking. In women, snuff was associated with lower systolic blood pressure. A total of 964 individuals (3.5%), i.e.544 men (5.3%) and 420 (2.5%) women suffered a MI during the follow-up period. The corresponding numbers of incident stroke cases were 1048, i.e. 553 men (5.3%) and 495 (3.0%) women, respectively. Snuff was not associated with any statistically significant increased risk of MI or stroke in men or women. The relative risks (RR) in male snuff users compared to non-users were 1.05 (95% confidence interval (CI): 0.8–1.4, p = 0.740) for incident MI and 0.97 (0.7–1.4, p = 0.878) for stroke, after taking age and potential confounders into account. In women none of the 420 (2.5%) women who were snuff users had a MI and only one suffered a stroke during the follow-up.

Conclusion

Several life-style risk factors were more prevalent in snuff-users than in non-users. However, the present study does not support any relationship between snuff and incidence of cardiovascular disease in men.

Smokeless tobacco use among men in the United States, 2000 and 2005

BACKGROUND

Compared with smoking, there is much less information about smokeless tobacco (ST) use in the United States. The purpose of this study is to characterize and compare ST use among American men in 2000 and 2005.

METHODS

We used US National Health Interview Surveys from 2000 and 2005 to estimate the prevalence of ST use, describe the demographic and socioeconomic profile of ST users and evaluate ST use according to product type and with respect to smoking.

RESULTS

The prevalence of ST use among American men was 4.4% in 2000 and 4.3% in 2005. Almost all ST users were white, about half were 25-44 years old and 80% lived in the South or Midwest, commonly in small metropolitan and rural areas. Educational and income levels of ST users were lower than those of never users of tobacco. One-third of ST users also smoked; cigarette consumption was lower among dual users than among exclusive smokers. In 2005, 1.3 million current ST users were former smokers but 3.2 million smokers were former ST users. ST users were evenly distributed between snuff (43%) and chewing tobacco (44%) in 2000 and 13% used both products. By 2005 snuff use was clearly dominant.

CONCLUSIONS

The prevalence of ST use among men is low but stable; dual use of cigarettes and ST is common, and snuff has become the dominant ST product.

The STAGE cohort: a prospective study of tobacco use among Swedish twins

We investigated patterns of cigarette smoking and Swedish snus (oral smokeless tobacco) use in a population-based sample of 19,073 Swedish twins 20-47 years old who participated in the baseline assessment of a prospective study of tobacco use and cessation in 2005-2006. Age-adjusted prevalence odds ratios (POR) and 95% confidence intervals (CI ) describe the association between tobacco use and sex, after adjustment for non-independence of twin pairs. Kaplan-Meier survival methods produced cumulative incidence curves of age at initiation of tobacco use. Slightly more than half of the baseline population was female (55.2%); the mean age at interview was 33.3 (+/-7.2) years and did not differ by sex. Having ever smoked daily was less common among males than females (11.9% vs. 15.3%; POR = 0.70 [0.64-0.77]), while having ever used snus daily was more common among males than females (31.1% vs. 4.8%; POR 11.7 [95% CI = 10.6-13.1]). The median age at initiation of smoking was 15 years for both sexes; median age at onset of snus use was 15 years for males and 18 years for females. Nicotine dependence scores were higher for males than females, and for current than former smokers. Findings from this study are in contrast to our previously published report on tobacco use among 32,123 Swedish twins 42-64 years old who completed a similar survey, and reported lower rates of snus use at later ages. Patterns of tobacco use may be changing in Sweden; snus use appears to be increasing, while daily smoking appears to be decreasing in popularity among the younger Swedish twins.

Systematic review of the relation between smokeless tobacco and cancer of the pancreas in Europe and North America

Background

Recent reviews claiming smokeless tobacco increases pancreatic cancer risk appear not to have considered all available epidemiological evidence; nor were meta-analyses included. We present a systematic review of studies from North America and Europe, since data are lacking from other continents. Risk is also difficult to quantify elsewhere due to the various products, compositions and usage practices involved.

Methods

Epidemiological studies were identified that related pancreatic cancer to use of snuff, chewing tobacco or unspecified smokeless tobacco. Study details and effect estimates (relative risks or odds ratios) were extracted, and combined by meta-analyses.

Results

Nine North American and two Scandinavian studies were identified. Reporting was limited in four studies, so only seven were included in meta-analyses, some providing results for never smokers, some for the overall population of smokers and non-smokers, and some for both.

Giving preference to study-specific estimates for the overall population, if available, and for never smokers otherwise, the random-effects estimate for ever smokeless tobacco use was 1.03 (95% confidence interval 0.71–1.49) based on heterogeneous estimates from seven studies. The estimate varied little by continent, study type, or type of smokeless tobacco.

Giving preference to estimates for never smokers, if available, and overall population estimates otherwise, the estimate was 1.14 (0.67–1.93), again based on heterogeneous estimates. Estimates varied (p = 0.014) between cohort studies (1.75, 1.20–2.54) and case-control studies (0.84, 0.36–1.97). The value for cohort studies derived mainly from one study, which reported an increase for never smokers (2.0, 1.2–3.3), but not overall (0.9, 0.7–1.2). This study also contributed to increases seen for snuff use and for European studies, significant only in fixed-effect analyses.

The studies have various weaknesses, including few exposed cases, reliance in cohort studies on exposure recorded at baseline, poor control groups in some case-control studies, and lack of a dose-response. Publication bias, with some negative studies not being presented, is also possible.

Conclusion

At most, the data suggest a possible effect of smokeless tobacco on pancreatic cancer risk. More evidence is needed. If any risk exists, it is highly likely to be less than that from smoking.

Snus use and other correlates of smoking cessation in the Swedish Twin Registry

BACKGROUND

We investigated 12 variables and their interactions as correlates of smoking cessation among regular smokers in the population-based Swedish Twin Registry (STR).

METHOD

Detailed information on tobacco use and personal characteristics were available from 14 715 male and female twins aged 42-64 years who participated in a screening of the population-based STR and reported being regular smokers in their lifetime. A two-stage analytic design was used to examine correlates of smoking cessation. The sample was split at random and significant main effects and interactions identified in the testing set were examined in the validation set. Hazard ratios (HRs) and 95% confidence intervals (CIs) describe the association between correlates and smoking cessation.

RESULTS

Twelve main effects were significantly associated with smoking cessation in the testing set; eight were confirmed in the validation set. Of the nine interactions identified in the testing set, none remained significant when evaluated in the validation set after Bonferroni correction. HRs were highest for Swedish oral smokeless tobacco (snus) use (HR 2.70, 95% CI 2.30-3.20), >11 years of education (HR 1.57, 95% CI 1.43-1.73) and being married or cohabitating (HR 1.51, 95% CI 1.39-1.63). Although not statistically significant after Bonferroni correction, snus use also appeared important in the context of interactions, where lower nicotine dependence score, higher socio-economic status (SES) and greater body size were associated with smoking cessation only among participants who never used snus.

CONCLUSIONS

Snus use was the strongest independent correlate of smoking cessation. Further studies should investigate the mechanism of this association.

Smokeless tobacco and cancer

Use of smokeless tobacco products is common worldwide, with increasing consumption in many countries. Although epidemiological data from the USA and Asia show a raised risk of oral cancer (overall relative risk 2.6 [95% CI 1.3-5.2]), these are not confirmed in northern European studies (1.0 [0.7-1.3]). Risks of oesophageal cancer (1.6 [1.1-2.3]) and pancreatic cancer (1.6 [1.1-2.2]) have also increased, as shown in northern European studies. Results on lung cancer have been inconsistent, with northern European studies suggesting no excess risk. In India and Sudan, more than 50% of oral cancers are attributable to smokeless tobacco products used in those countries, as are about 4% of oral cancers in US men and 20% of oesophageal and pancreatic cancers in Swedish men. Smokeless tobacco products are a major source of carcinogenic nitrosamines; biomarkers of exposure have been developed to quantify exposure as a framework for a carcinogenesis model in people. Animal carcinogenicity studies strongly support clinical results. Cancer risk of smokeless tobacco users is probably lower than that of smokers, but higher than that of non-tobacco users.

Systematic review of the relation between smokeless tobacco and non-neoplastic oral diseases in Europe and the United States

Background

How smokeless tobacco contributes to non-neoplastic oral diseases is unclear. It certainly increases risk of oral mucosal lesions, but reviewers disagree as to other conditions. In some areas, especially South-East Asia, risk is difficult to quantify due to the many products, compositions (including non-tobacco ingredients), and usage practices involved. This review considers studies from Europe (in practice mainly Scandinavia) and from the USA.

Methods

Experimental and epidemiological studies published in 1963–2007 were identified that related risk of oral lesions to smokeless tobacco use. Data were assessed separately for oral mucosal lesions, periodontal and gingival diseases, dental caries and tooth loss, and oral pain.

Results

Oral mucosal lesions: Thirty-three epidemiological studies consistently show a strong dose-related effect of current snuff on oral mucosal lesion prevalence. In Scandinavia, users have a near 100% prevalence of a characteristic "snuff-induced lesion", but prevalence of the varied lesions reported in the USA is lower. Associations with chewing tobacco are weaker. The lack of clear association with former use suggests reversibility following cessation, consistent with experimental studies showing rapid lesion regression on quitting.

Periodontal and gingival diseases: Two of four studies report a significant association of snuff with attachment loss and four out of eight with gingival recession. Snuff is not clearly related to gingivitis or periodontal diseases. Limited evidence suggests chewing tobacco is unrelated to periodontal or gingival diseases.

Tooth loss: Swedish studies show no association with snuff, but one US study reported an association with snuff, and another with chewing tobacco.

Dental caries: Evidence from nine studies suggests a possible relationship with use of smokeless tobacco, particularly chewing tobacco, and the risk of dental caries.

Oral pain: Limited evidence precludes any clear conclusion.

Conclusion

This review confirms the strong association of current use of smokeless tobacco, particularly snuff, with prevalence of oral mucosal lesions. It provides suggestive evidence of an association of snuff use with gingival recession and attachment loss, and of chewing tobacco with dental caries. While smokeless tobacco clearly increases risk of oral mucosal lesions, interpretation for other endpoints is limited by study weaknesses, including poor confounding control.