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Health effects associated with smokeless tobacco: a systematic review.

ABSTRACT: BACKGROUND:It is believed that health risks associated with smokeless tobacco (ST) use are lower than those with cigarette smoking. A systematic review was therefore carried out to summarise these risks. METHODS:Several electronic databases were searched, supplemented by screening reference lists, smoking related websites, and contacting experts. Analytical observational studies of ST use (cohorts, case-control, cross sectional studies) with a sample size of >/=500 were included if they reported on one or more of the following outcomes (all cause mortality, oral and pharyngeal cancers, other cancers, cardiovascular diseases, dental diseases, pregnancy outcomes, surgical outcomes). Data extraction covered control of confounding, selection of cases and controls, sample size, clear definitions and measurements of the health outcome, and ST use. Selection, extraction and quality assessments were carried out by one or two independent reviewers. RESULTS:A narrative review was carried out. Many of the studies lacked sufficient power to estimate precise risks, mainly due to the small number of ST users. Studies were often not designed to investigate ST use, and many also had major methodological limitations including poor control for cigarette smoking and imprecise measurements of exposure. Studies in India showed a substantial risk of oral or oropharyngeal cancers associated with chewing betel quid and tobacco. Studies from other regions and of other cancer types were not consistent. Few studies have adequately considered the non-cancer health effects of ST use. CONCLUSIONS:Chewing betel quid and tobacco is associated with a substantial risk of oral cancers in India. Most recent studies from the US and Scandinavia are not statistically significant, but moderate positive associations cannot be ruled out due to lack of power. Further rigorous studies with adequate sample sizes are required, especially for cardiovascular disease.

SUBMITTER: Critchley JA

PROVIDER: S-EPMC1746661 | biostudies-literature | 2003 May

REPOSITORIES: biostudies-literature

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Health effects associated with smokeless tobacco: a systematic review.

Critchley J A JA Unal B B

Thorax 20030501 5

<h4>Background</h4>It is believed that health risks associated with smokeless tobacco (ST) use are lower than those with cigarette smoking. A systematic review was therefore carried out to summarise these risks.<h4>Methods</h4>Several electronic databases were searched, supplemented by screening reference lists, smoking related websites, and contacting experts. Analytical observational studies of ST use (cohorts, case-control, cross sectional studies) with a sample size of >/=500 were included i ...[more]

PMID: 12728167

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Project description:IntroductionSmokeless tobacco (ST) was consumed by 356 million people globally in 2017. Recent evidence shows that ST consumption is responsible for an estimated 652 494 all-cause deaths across the globe annually. The WHO Framework Convention on Tobacco Control (FCTC) was negotiated in 2003 and ratified in 2005 to implement effective tobacco control measures. While the policy measures enacted through various tobacco control laws have been effective in reducing the incidence and prevalence of smoking, the impact of ST-related policies (within WHO FCTC and beyond) on ST use is under-researched and not collated.Methods and analysisA systematic review will be conducted to collate all available ST-related policies implemented across various countries and assess their impact on ST use. The following databases will be searched: Medline, EMBASE, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Scopus, EconLit, ISI Web of Science, Cochrane Library (CENTRAL), African Index Medicus, LILACS, Scientific Electronic Library Online, Index Medicus for the Eastern Mediterranean Region, Index Medicus for South-East Asia Region, Western Pacific Region Index Medicus and WHO Library Database, as well as Google search engine and country-specific government websites. All ST-related policy documents (FCTC and non-FCTC) will be included. Results will be limited to literature published since 2005 in English and regional languages (Bengali, Hindi and Urdu). Two reviewers will independently employ two-stage screening to determine inclusion. The Effective Public Health Practice Project's 'Quality Assessment Tool for Quantitative Studies' will be used to record ratings of quality and risk of bias among studies selected for inclusion. Data will be extracted using a standardised form. Meta-analysis and narrative synthesis will be used.Ethics and disseminationPermission for ethics exemption of the review was obtained from the Centre for Chronic Disease Control's Institutional Ethics Committee, India (CCDC_IEC_06_2020; dated 16 April 2020). The results will be disseminated through publications in a peer-reviewed journal and will be presented in national and international conferences.Prospero registration numberCRD42020191946.

Project description:There are an estimated 8 million users of smokeless tobacco products (STPs) in the United States, and yet limited data on microbial populations within these products exist. To better understand the potential microbiological risks associated with STP use, a study was conducted to provide a baseline microbiological profile of STPs. A total of 90 samples, representing 15 common STPs, were purchased in metropolitan areas in Little Rock, AR, and Washington, DC, in November 2012, March 2013, and July 2013. Bacterial populations were evaluated using culture, pyrosequencing, and denaturing gradient gel electrophoresis (DGGE). Moist-snuff products exhibited higher levels of bacteria (average of 1.05 × 106 CFU/g STP) and diversity of bacterial populations than snus (average of 8.33 × 101 CFU/g STP) and some chewing tobacco products (average of 2.54 × 105 CFU/g STP). The most common species identified by culturing were Bacillus pumilus, B. licheniformis, B. safensis, and B. subtilis, followed by members of the genera Oceanobacillus, Staphylococcus, and Tetragenococcus. Pyrosequencing analyses of the 16S rRNA genes identified the genera Tetragenococcus, Carnobacterium, Lactobacillus, Geobacillus, Bacillus, and Staphylococcus as the predominant taxa. Several species identified are of possible concern due to their potential to cause opportunistic infections and reported abilities to reduce nitrates to nitrites, which may be an important step in the formation of carcinogenic tobacco-specific N'-nitrosamines. This report provides a microbiological baseline to help fill knowledge gaps associated with microbiological risks of STPs and to inform potential regulations regarding manufacture and testing of STPs.ImportanceIt is estimated that there 8 million users of smokeless tobacco products (STPs) in the United States; however, there are limited data on microbial populations that exist within these products. The current study was undertaken to better understand the potential microbiological risks associated with STP use and provide a baseline microbiological profile of STPs. Several bacterial species were identified that are of possible concern due to their potential to cause opportunistic infections. In addition, some species have abilities to reduce nitrates to nitrites, which may be an important step in the formation of carcinogenic tobacco-specific N'-nitrosamines. Overall, this report provides a microbiological baseline to help fill knowledge gaps related to the microbiological risks of STPs and to inform potential regulations regarding the manufacture and testing of STPs.

Project description:BackgroundUse of smokeless tobacco (SLT) products has been linked to multiple adverse effects, especially precancer and cancer of oral cavity. However, the association of SLT use with risk of coronary heart disease (CHD) is shrouded with controversy due to conflicting results in the literature. The present meta-analysis aimed to evaluate the risk of CHD among adult ever-users of SLT products along with sub-group analysis.MethodsThe analysis included studies retrieved from a systematic literature search for published articles assessing risk of CHD with SLT use. Two authors independently extracted risk estimates and study characteristics of the included studies. Summary relative risks were estimated using the random-effect model.ResultsTwenty studies from four WHO regions were included in the analysis. The summary risk of CHD in SLT users was not significantly positive (1.05, 95% CI = 0.96 to 1.15) although a higher risk of fatal CHD was seen (1.10, 95% CI = 1.00 to 1.20). The risk was significant for users in European Region (1.30, 95% CI = 1.14 to 1.47). The results remained unchanged even after strict adjustment for smoking. Product-wise analysis revealed a significant positive association of fatal CHD with snus/snuff use (1.37, 95% CI = 1.14 to 1.61). The SLT-attributable fraction of fatal CHD was calculated to be 0.3%, highest being for European region (5%).ConclusionA significant positive association was detected between SLT use and risk of fatal CHD, especially for European users and those consuming snus/snuff. In view of the positive association even after strict adjustment for smoking, these results underscore the need for inclusion of cessation efforts for smokeless tobacco in addition to smoking for control of fatal cardiovascular diseases.ImplicationsThe present meta-analysis demonstrates a global perspective of association between coronary heart disease (CHD) and use of smokeless tobacco (SLT), especially for fatal cardiac events, even with strict adjustment for smoking. There appears to be some difference in this effect based on the type of SLT product used. These results highlight the independent deleterious effect of SLT products on the outcome of CHD and might help to resolve the long-standing controversy regarding the association of SLT with the risk of CHD. Hence, we propose that in addition to smoking, cessation efforts should be directed towards SLT products as well, for control of cardiovascular diseases.

Project description:Smokeless tobacco products (STP) contain diverse microbial communities that contribute to the formation of harmful chemical byproducts. This is concerning since 300 million individuals around the globe are users of smokeless tobacco. Significant evidence has shown that microbial metabolic activities mediate the formation of carcinogens during manufacturing. In recent years, studies have revealed a series of additional health impacts that include lesions and inflammation of the oral mucosa and the gastrointestinal tract, as well as alterations of the endogenous microbiota. These findings are due to recent developments in molecular technologies that allowed researchers to better examine the microbial component of these products. This new information illustrates the scale of the STP microbiota and its diversity in the finished product that is sold for consumption. Additionally, the application of metagenomics and metatranscriptomics has provided the tools to look at phylogenies across bacterial, viral, and eukaryotic groups, their functional capacities, and viability. Here we present key examples of tobacco microbiology research that utilizes newer approaches and strategies to define the microbial component of smokeless tobacco products. We also highlight challenges in these approaches, the knowledge gaps being filled, and those gaps that warrant further study. A better understanding of the microbiology of STP brings vast public health benefits. It will provide important information for the product consumer, impact manufacturing practices, and provide support for the development of attainable and more meaningful regulatory goals. KEY POINTS: Newer technologies allowed quicker and more comprehensive identification of microbes in tobacco samples, encapsulating microorganisms difficult or impossible to culture. Current research in smokeless tobacco microbiology is filling knowledge gaps previously unfilled due to the lack of suitable approaches. The microbial ecology of smokeless tobacco presents a clearer picture of diversity and variability not considered before.

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Health effects associated with smokeless tobacco: a systematic review.

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Health effects associated with smokeless tobacco: a systematic review.

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