Biomarkers to assess the utility of potential reduced exposure tobacco products

Clinical study protocol on electronic cigarettes and nicotine pouches for smoking cessation in Pakistan: a randomized controlled trial

BACKGROUND

Pakistan is one of most vulnerable low- and middle-income countries with 29 million adult active tobacco users. Smoking cessation services are lacking as the tobacco control initiatives have largely failed to address the smoking endemic. Over the last 5 years, Pakistan has witnessed the use of innovative tobacco harm reduction (THR) products such as e-cigarettes and nicotine pouches. However, their use remains limited. THR products are imported legally as consumer goods and are taxable. The lack of sufficient data for THR and its application is a challenge in gauging their effectiveness in assisting smokers quit combustible smoking. Evidence-based studies can help in measuring the effectiveness of e-cigarettes and nicotine pouches as smoking cessation aids.

METHOD

Keeping in view the study objectives, a sample size of 600 participants will be sufficient to assess the effectiveness of e-cigarettes and nicotine pouches for smoking cessation in Pakistan. Of these, 200 participants each will receive e-cigarettes and nicotine pouches along with basic care counselling, while the remaining 200 participants will only receive basic care counselling for 48 weeks. The association of participants' characteristics with smoking and health status will be based on the bivariate and multivariate analysis. The simple t-test and variance analysis will assess the differences in intervention indicators between the control and treatment groups. For the inferential analysis, the average treatment impact will be based on the quasi-experimental techniques such as difference in difference (DID) or propensity score matching (PMS).

DISCUSSION

The study will evaluate the participants at the baseline as they decide the quit date. After every 12 weeks, a follow-up survey with the participants will be conducted. Results are anticipated to inform the public, decision-makers, and researchers about the effects of using e-cigarettes and nicotine pouches in the short- and medium-term periods. Critically, the potential of e-cigarettes and other alternative nicotine delivery systems as smoking cessation aid will be assessed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05715164 . Registered on February 6, 2023.

PROTOCOL VERSION

Protocol version 1.0, 14-12-2022 Trial in progress and not yet recruiting participants. Estimated primary data collection date-April 2024.

Associations between biomarkers of nicotine/tobacco exposure and respiratory symptoms among adults who exclusively smoke cigarettes in the U.S.: Findings from the PATH Study Waves 1-4 (2013-2017)

Significance

Determining if tobacco-related biomarkers of exposure (BOE) are associated with respiratory symptoms is an important public health tool that can be used to evaluate the potential harm of different tobacco products.

Methods

Adult data from people who exclusively smoked cigarettes (N = 2,438) in Waves 1-4 (2013-2017) of the Population Assessment of Tobacco and Health Study were stacked to examine associations between baseline and follow-up within wave pairs (W1-W2, W2-W3, W3-W4). Weighted generalized estimating equation models were used to evaluate associations between biomarkers of nicotine, tobacco-specific nitrosamines, acrolein, acrylonitrile, cadmium, and lead at baseline/follow-up and respiratory symptom(s) (wheezing/whistling in the chest, wheezing during exercise, and/or dry cough in the past 12 months) at follow-up.

Results

Higher acrolein metabolite (CEMA) levels at follow-up were associated with increased odds of respiratory symptoms at follow-up for people who exclusively smoked cigarettes (aOR = 1.34; 95% CI = 1.06, 1.70), including when limited to those without a diagnosed respiratory disease (aOR = 1.46; 95% CI = 1.12, 1.90) and those who smoked daily (aOR = 1.40; 95% CI = 1.06, 1.84). Higher cadmium levels at baseline (while controlling for follow-up levels) were associated with reduced odds of respiratory symptoms at follow-up (aOR = 0.80; 95% CI = 0.65, 0.98) among people who exclusively smoked cigarettes without a respiratory disease. There were no significant associations between baseline/follow-up BOE and follow-up respiratory symptoms for people who smoked cigarettes non-daily.

Conclusions

This research supports measuring biomarkers of acrolein, such as CEMA, as a potential intermediate measurement for increased respiratory symptom development. Measuring these biomarkers could help alleviate the clinical burden of respiratory disease.

Changes in biomarkers of exposure and biomarkers of potential harm after 360 days in smokers who either continue to smoke, switch to a tobacco heating product or quit smoking

The aim of this study was to investigate whether biomarkers of exposure (BoE) and potential harm (BoPH) are modified when smokers either continue to smoke or switch from smoking cigarettes to exclusive use of a tobacco heating product (THP) in an ambulatory setting over the period of a year, and to compare any changes with smokers who quit tobacco use completely and with never smokers' biomarker levels. Participants in this year-long ambulatory study were healthy smokers with a self-reported low intent to quit assigned either to continue smoking or switch to a THP; a group of smokers with a self-reported high intent to quit who abstained from tobacco use; and a group of never smokers. Various BoE and BoPH related to oxidative stress, cardiovascular and respiratory diseases and cancer were assessed at baseline and up to 360 days. Substantial and sustained reductions in BoE levels were found at 360 days for both participants who switched from smoking to THP use and participants who quit smoking, in many cases the reductions being of a similar order for both groups. The never smoker group typically had lower levels of the measured BoEs than either of these groups, and much lower levels than participants who continued to smoke. Several BoPHs were found to change in a favourable direction (towards never smoker levels) over the year study for participants who completely switched to THP or quit, while BoPHs such as soluble intercellular adhesion molecule-1 were found to change in an unfavourable direction (away from never smoker levels) in participants who continued to smoke. Our findings, alongside chemical and toxicological studies undertaken on the THP used in this study, lead to the conclusion that smokers who would have otherwise continued to smoke and instead switch entirely to the use of this THP, will reduce their exposure to tobacco smoke toxicants and as a consequence are reasonably likely to reduce disease risks compared to those continuing to smoke.

Understanding heterogeneity among individuals who smoke cigarettes and vape: assessment of biomarkers of exposure and potential harm among subpopulations from the PATH Wave 1 Data

Introduction

People who both smoke cigarettes and vape are often considered as a homogenous group even though multiple subgroups may exist. We examined biomarkers of exposure (BOE) and biomarkers of potential harm (BOPH) to differentiate between subgroups of people who smoke and vape based on PATH Study Wave 1 (2013–2014) data.

Methods

We compared people who only smoke cigarettes everyday (Group A, n = 2442) and people who only vape everyday (Group C, n = 169) against people who smoke and vape segmented into subgroups of people who frequently smoke and vape (Group B1, n = 169), frequently smoke and infrequently vape (Group B2, n = 678), frequently vape and infrequently smoke (Group B3, n = 57), and infrequently smoke and vape (Group B4, n = 66). Eighteen BOEs (representing exposure to TSNAs, nicotine, heavy metals, PAHs, and volatile organic compounds) and four BOPHs (representing inflammation and oxidative stress) were compared within the subgroups.

Results

Levels of many BOEs/BOPHs were higher among Group B2 relative to Groups B1, B3, and B4. Compared to Group A, many BOEs were significantly lower in Groups B3 (15/18) and B4 (17/18), and some BOEs were higher among B2 (4/18). Compared to Group C, significantly lower BOEs were observed for Group B4 (2/18).

Conclusions

Overall, the levels of BOEs and BOPHs in people who smoke and vape are associated with frequency of cigarette smoking. Our findings indicate that not all people who smoke and vape are the same, and tobacco product use frequency should be considered when categorizing people who smoke and vape.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12954-022-00673-x.

Changes in biomarkers after 180 days of tobacco heating product use: a randomised trial

The aim of this study was to investigate whether biomarkers of exposure (BoE) and potential harm (BoPH) are modified when smokers switch from smoking cigarettes to exclusive use of a tobacco heating product (THP) in an ambulatory setting. Participants in this randomised, controlled study were healthy volunteer smokers assigned either to continue smoking or switch to a THP, and a control group of smokers who abstained from cigarette smoking. Various BoE and BoPH related to oxidative stress, cardiovascular and respiratory diseases, and cancer were assessed at baseline and up to 180 days. In continuing smokers, BoE and BoPH remained stable between baseline and day 180, while THP users' levels of most BoE reduced significantly, becoming similar to those in controls abstaining from cigarette smoking. Also at 180 days, significant changes in numerous BoPH, including total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, 8-epi-prostaglandin F2α type III, fractional concentration of exhaled nitric oxide and white blood cell count, were directionally consistent with lessened health impact. Our findings support the notion that the deleterious health impacts of cigarette smoking may be reduced in smokers who completely switch to using THPs.

Biomarkers of Toxicant Exposure and Inflammation Among Women of Reproductive Age Who Use Electronic or Conventional Cigarettes

Background: Electronic cigarettes (e-cigarettes) generally have a more favorable toxicant profile than conventional cigarettes; however, limited information exists for women of reproductive age (WRA). Our aim was to compare biomarkers of toxicant exposure, inflammation, and oxidative stress among WRA who self-report exclusive e-cigarette use, exclusive cigarette smoking, or never tobacco use (controls). Methods: Multivariable linear regression models were used to compare the geometric means of urinary biomarkers of toxicant exposure and their metabolites, serum markers of inflammation [highly sensitive C-reactive protein, soluble intercellular adhesion molecule (sICAM), interleukin 6, fibrinogen], and a measurement of oxidative stress [prostaglandin F2a-8-isoprostane (F2PG2a)] among WRA from the Population Assessment of Tobacco and Health survey. Results: E-cigarette users had higher levels of lead, tobacco-specific nitrosamines, nicotine metabolites, and some volatile organic compounds (VOCs) than controls. Except for cadmium and lead, e-cigarette users had lower levels of the analyzed urinary toxicant biomarkers compared with cigarette smokers. Cigarette smokers had higher levels of all the biomarkers of toxicant exposure than controls. There were no significant differences in the levels of markers of inflammation and oxidative stress between e-cigarette users and controls. E-cigarette users and controls had lower levels of sICAM and F2PG2a than cigarette smokers. Conclusion: WRA who use e-cigarettes had lower levels of some of the evaluated urinary biomarkers of toxicant exposure and serum biomarkers of inflammation and oxidative stress than those who smoke cigarettes, but higher lead, nicotine metabolites, and some VOCs than controls, which can increase health risks.

PhenX: Host: Biobehavioral measures for tobacco regulatory research

A working group (WG) of experts from diverse fields related to nicotine and tobacco addiction was constituted to identify constructs and measures for the PhenX (Phenotypes and eXposures) Tobacco Regulatory Research (TRR) Host: Biobehavioral Collection with potential relevance to users of both conventional and newer tobacco products. This paper describes the methods and results the WG used to identify, select, approve and place measures in the PhenX TRR Collection. The WG recognised 13 constructs of importance to guide their categorisation of measures already in the PhenX Toolkit ('complementary measures') and to identify novel or improved measures of special relevance to tobacco regulatory science. In addition to the 22 complementary measures of relevance to tobacco use already in the PhenX Toolkit, the WG identified and recommended nine additional Host: Biobehavioral measures characterising the use, exposure and health outcomes of tobacco products for application to TRR. Of these, five were self-administered or interviewer-administered measures: amount, type and frequency of recent tobacco use; flavor preference in e-cigarette users (adult and youth); pregnancy status and tobacco use; pregnancy status-mother and baby health and withdrawal from tobacco use. The remaining four measures were laboratory-based: cotinine in serum, expired carbon monoxide, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in urine and cue reactivity. Although a number of validated tools are now available in the Host: Biobehavioral Collection, several gaps were identified, including a need to develop and test the identified measures in adolescent samples and to develop or identify measures of nicotine dependence, tolerance and withdrawal associated with newer non-combusted tobacco products.

Biomarkers of Tobacco Exposure: Summary of an FDA-Sponsored Public Workshop

Since 2009, the FDA Center for Tobacco Products (CTP) has had the authority to regulate the manufacturing, distribution, and marketing of tobacco products in order to reduce the death and disease caused by tobacco use. Biomarkers of exposure pertain to actual human exposure to chemicals arising from tobacco use and could play an important role across a number of FDA regulatory activities, including assessing new and modified-risk tobacco products and identifying and evaluating potential product standards. On August 3-4, 2015, FDA/CTP hosted a public workshop focused on biomarkers of exposure with participants from government, industry, academia, and other organizations. The workshop was divided into four sessions focused on: (i) approaches to evaluating and selecting biomarkers; (ii) biomarkers of exposure and relationship to disease risk; (iii) currently used biomarkers of exposure and biomarkers in development; and (iv) biomarkers of exposure and the assessment of smokeless tobacco and electronic nicotine delivery systems. This article synthesizes the main findings from the workshop and highlights research areas that could further strengthen the science around biomarkers of exposure and help determine their application in tobacco product regulation. Cancer Epidemiol Biomarkers Prev; 26(3); 291-302. ©2016 AACR.

Persistent alterations of gene expression profiling of human peripheral blood mononuclear cells from smokers

The number of validated biomarkers of tobacco smoke exposure is limited, and none exist for tobacco-related cancer. Additional biomarkers for smoke, effects on cellular systems in vivo are needed to improve early detection of lung cancer, and to assist the Food and Drug Administration in regulating exposures to tobacco products. We assessed the effects of smoking on the gene expression using human cell cultures and blood from a cross-sectional study. We profiled global transcriptional changes in cultured smokers' peripheral blood mononuclear cells (PBMCs) treated with cigarette smoke condensate (CSC) in vitro (n = 7) and from well-characterized smokers' blood (n = 36). ANOVA with adjustment for covariates and Pearson correlation were used for statistical analysis in this study. CSC in vitro altered the expression of 1 178 genes (177 genes with > 1.5-fold-change) at P < 0.05. In vivo, PBMCs of heavy and light smokers differed for 614 genes (29 with > 1.5-fold-change) at P < 0.05 (309 remaining significant after adjustment for age, race, and gender). Forty-one genes were persistently altered both in vitro and in vivo, 22 having the same expression pattern reported for non-small cell lung cancer. Our data provides evidence that persistent alterations of gene expression in vitro and in vivo may relate to carcinogenic effects of cigarette smoke, and the identified genes may serve as potential biomarkers for cancer. The use of an in vitro model to corroborate results from human studies provides a novel way to understand human exposure and effect. © 2015 Wiley Periodicals, Inc.

Evaluating the relationship between biomarkers of potential harm and biomarkers of tobacco exposure among current, past, and nonsmokers: data from the National Health and Nutrition Examination Survey 2007-2012

Potential long-term health effects from tobacco products can be estimated by measuring changes in biochemical indicators of disease mechanisms like inflammation. This study assesses the potential relationships between biomarkers of potential harm (BOPH) and biomarkers of cigarette smoke exposure (BOE) based on data from the NHANES (2007-2012, n = 17,293 respondents). Statistically significant relationships were observed between white blood cells (WBC) and high-density lipoprotein (HDL) and BOE; between WBC and high-sensitivity C-reactive protein and smoking status; and between WBC and HDL and smoking intensity. This analysis suggests that WBC and HDL are useful BOPH in studies assessing the health risks of cigarette smoking.

Switching from usual brand cigarettes to a tobacco-heating cigarette or snus: Part 2. Biomarkers of exposure

A randomized, multi-center study of adult cigarette smokers switched to tobacco-heating cigarettes, snus or ultra-low machine yield tobacco-burning cigarettes (50/group) was conducted, and subjects' experience with the products was followed for 24 weeks. Differences in biomarkers of tobacco exposure between smokers and never smokers at baseline and among groups relative to each other and over time were assessed. Results indicated reduced exposure to many potentially harmful constituents found in cigarette smoke following product switching. Findings support differences in exposure from the use of various tobacco products and are relevant to the understanding of a risk continuum among tobacco products (ClinicalTrials.gov Identifier: NCT02061917).

Switching from usual brand cigarettes to a tobacco-heating cigarette or snus: Part 3. Biomarkers of biological effect

A randomized, multi-center study of adult cigarette smokers switched to tobacco-heating cigarettes, snus or ultra-low machine yield tobacco-burning cigarettes (50/group) for 24 weeks was conducted. Evaluation of biomarkers of biological effect (e.g. inflammation, lipids, hypercoaguable state) indicated that the majority of consistent and statistically significant improvements over time within each group were observed in markers of inflammation. Consistent and statistically significant differences in pairwise comparisons between product groups were not observed. These findings are relevant to the understanding of biomarkers of biological effect related to cigarette smoking as well as the risk continuum across various tobacco products (ClinicalTrials.gov Identifier: NCT02061917).

A CHRNA5 Smoking Risk Variant Decreases the Aversive Effects of Nicotine in Humans

Genome-wide association studies have implicated the CHRNA5-CHRNA3-CHRNB4 gene cluster in risk for heavy smoking and several smoking-related disorders. The heavy smoking risk allele might reduce the aversive effects of nicotine, but this hypothesis has not been tested in humans. We evaluated the effects of a candidate causal variant in CHRNA5, rs16969968, on the acute response to nicotine in European American (EA) and African American (AA) smokers (n=192; 50% AA; 73% male). Following overnight abstinence from nicotine, participants completed a protocol that included an intravenous (IV) dose of saline and two escalating IV doses of nicotine. The outcomes evaluated were the aversive, pleasurable, and stimulatory ratings of nicotine's effects, cardiovascular reactivity to nicotine, withdrawal severity, and cognitive performance before and after the nicotine administration session. The heavy smoking risk allele (rs16969968*A; frequency=28% (EA) and 6% (AA)) was associated with lower ratings of aversive effects (P<5 × 10(-8)) with marked specificity. This effect was evident in EA and AA subjects analyzed as separate groups and was most robust at the highest nicotine dose. Rs16969968*A was also associated with greater improvement on a measure of cognitive control (Stroop Task) following nicotine administration. These findings support differential aversive response to nicotine as one likely mechanism for the association of CHRNA5-CHRNA3-CHRNB4 with heavy smoking.

Providing a Science Base for the Evaluation of Tobacco Products

OBJECTIVE

Evidence-based tobacco regulation requires a comprehensive scientific framework to guide the evaluation of new tobacco products and health-related claims made by product manufacturers.

METHODS

The Tobacco Product Assessment Consortium (TobPRAC) employed an iterative process involving consortia investigators, consultants, a workshop of independent scientists and public health experts, and written reviews in order to develop a conceptual framework for evaluating tobacco products.

RESULTS

The consortium developed a four-phased framework for the scientific evaluation of tobacco products. The four phases addressed by the framework are: (1) pre-market evaluation, (2) pre-claims evaluation, (3) post-market activities, and (4) monitoring and re-evaluation. For each phase, the framework proposes the use of validated testing procedures that will evaluate potential harms at both the individual and population level.

CONCLUSIONS

While the validation of methods for evaluating tobacco products is an ongoing and necessary process, the proposed framework need not wait for fully validated methods to be used in guiding tobacco product regulation today.

Evaluation of health promotion programmes in severe mental illness: theory and practice

Health promotion programmes for patients with severe mental illness (HPP) are not uniformly evaluated. We discuss the evaluation of HPP in theory and practice, as a prerequisite for future uniform evaluation. We explored the expected outcome and mechanism of HPP in the current literature. Based on this theoretical exploration we selected measures assessing the expected outcome and mechanism in current practice. The individual properties of these measures were described. Based on our theoretical exploration the outcome of HPP can be expressed in several aspects of health. Health can be improved through several mechanisms. In the current evaluation of HPP only some of the expected outcomes were evaluated. The measures used for evaluation were not all representative for the constructs they should assess. Important aspects of HPP are currently not evaluated, based on a comparison between our theoretical exploration of expected outcome and mechanism and current practice. Additionally, not all measures in use are suitable for evaluation of HPP. Therefore, development and identification of suitable measures is necessary. Our framework offers valuable directions for the development of such measures and the future evaluation of HPP.

Magnitudes of biomarker reductions in response to controlled reductions in cigarettes smoked per day: a one-week clinical confinement study

Tobacco toxicant-related exposure reduction is an important tool in harm reduction. Cigarette per day reduction (CPDR) occurs as smokers migrate from smoking cigarettes to using alternative tobacco/nicotine products, or quit smoking. Few reports characterize the dose-response relationships between CPDR and effects on exposure biomarkers, especially at the low end of CPD exposure (e.g., 5 CPD). We present data on CPDR by characterizing magnitudes of biomarker reductions. We present data from a well-controlled, one-week clinical confinement study in healthy smokers who were switched from smoking 19-25 CPD to smoking 20, 10, 5 or 0 CPD. Biomarkers were measured in blood, plasma, urine, and breath, and included smoke-related toxicants, urine mutagenicity, smoked cigarette filter analyses (mouth level exposure), and vital signs. Many of the biomarkers (e.g., plasma nicotine) showed strong CPDR dose-response reductions, while others (e.g., plasma thiocyanate) showed weaker dose-response reductions. Factors that lead to lower biomarker reductions include non-CPD related contributors to the measured response (e.g., other exposure sources from environment, life style, occupation; inter-individual variability). This study confirms CPDR dose-responsive biomarkers and suggests that a one-week design is appropriate for characterizing exposure reductions when smokers switch from cigarettes to new tobacco products.

Nicotine exposure, blood pressure, and inflammation in tobacco smokers and chewers in a rural community in Nepal

Tobacco consumption is high amongst the people of Xxx. This study was carried out in 2011 in a rural community of Xxx, to compare pathological parameters associated with tobacco use in relation to nicotine metabolism between smokers, chewers, and a control group. A total of 216 volunteers provided blood and urine samples for testing nicotine metabolites, C-reactive protein, and cell counts. Data were analyzed using ANOVA, correlation, and t-tests using STATA. Differences in blood pressure amongst the groups indicate a role of smoking in preventing a rise in BP with age, likely attributable to a different mechanism of metabolism of tobacco constituents.

Cotinine concentration in serum correlates with tobacco smoke-induced emphysema in mice

Secondhand smoke (SHS) has been associated with a variety of adverse health outcomes in nonsmokers, including emphysema (a chronic obstructive pulmonary disease). One way to detect SHS exposure is to measure the concentration of cotinine, the primary metabolite of nicotine, in bodily fluids. We have developed a method for cotinine analysis by combining micellar electrokinetic chromatography with enrichment techniques. We employed the method to measure cotinine concentrations in serum samples of mice exposed to tobacco smoke for 12 or 24 weeks and found that it was 3.1-fold or 4.8-fold higher than those exposed to room air for the same period. Further, we investigated the morphological changes in lungs of mice and observed tobacco smoke induced emphysema. Our results indicate that the method can be used to measure cotinine and there is an association between the serum cotinine concentration and tobacco smoke-induced emphysema in mice.

Urinary biomarkers of smokers' exposure to tobacco smoke constituents in tobacco products assessment: a fit for purpose approach

There are established guidelines for bioanalytical assay validation and qualification of biomarkers. In this review, they were applied to a panel of urinary biomarkers of tobacco smoke exposure as part of a "fit for purpose" approach to the assessment of smoke constituents exposure in groups of tobacco product smokers. Clinical studies have allowed the identification of a group of tobacco exposure biomarkers demonstrating a good doseresponse relationship whilst others such as dihydroxybutyl mercapturic acid and 2-carboxy-1-methylethylmercapturic acid - did not reproducibly discriminate smokers and non-smokers. Furthermore, there are currently no agreed common reference standards to measure absolute concentrations and few inter-laboratory trials have been performed to establish consensus values for interim standards. Thus, we also discuss in this review additional requirements for the generation of robust data on urinary biomarkers, including toxicant metabolism and disposition, method validation and qualification for use in tobacco products comparison studies.

Lung cancer biomarkers for the assessment of modified risk tobacco products: an oxidative stress perspective

Manufacturers have developed prototype cigarettes yielding reduced levels of some tobacco smoke toxicants, when tested using laboratory machine smoking under standardised conditions. For the scientific assessment of modified risk tobacco products, tests that offer objective, reproducible data, which can be obtained in a much shorter time than the requirements of conventional epidemiology are needed. In this review, we consider whether biomarkers of biological effect related to oxidative stress can be used in this role. Based on published data, urinary 8-oxo-7,8-dihydro-2-deoxyguanosine, thymidine glycol, F2-isoprostanes, serum dehydroascorbic acid to ascorbic acid ratio and carotenoid concentrations show promise, while 4-hydroxynonenal requires further qualification.

Feasibility of identifying the tobacco-related global metabolome in blood by UPLC-QTOF-MS

Metabolomics is likely an ideal tool to assess tobacco smoke exposure and the impact of cigarette smoke on human exposure and health. To assess reproducibility and feasibility of this by UPLC-QTOF-MS, three experiments were designed for the assessment of smokers' blood. Experiment I was an analysis of 8 smokers with 8 replicates. Experiment II was an analysis of 62 pooled quality control (QC) samples from 7 nonsmokers' plasma placed as every tenth sample among a study of 613 samples from 160 smokers. Finally, to examine the feasibility of metabolomic study in assessing smoke exposure, Experiment III consisted of 9 smokers and 10 nonsmokers' serum to evaluate differences in their global metabolome. There was minimal measurement and sample preparation variation in all experiments, although some caution is needed when analyzing specific parts of the chromatogram. When assessing QC samples in the large scale study, QC clustering indicated high stability, reproducibility, and consistency. Finally, in addition to the identification of nicotine metabolites as expected, there was a characteristic profile distinguishing smokers from nonsmokers. Metabolites selected from putative identifications were verified by MS/MS, showing the potential to identify metabolic phenotypes and new metabolites relating to cigarette smoke exposure and toxicity.

Socioeconomic, demographic and smoking-related correlates of the use of potentially reduced exposure to tobacco products in a national sample

BACKGROUND AND AIM

In recent years, new non-traditional, potentially reduced exposure products (PREPs), claiming to contain fewer harmful chemicals than the traditional products, have been introduced in the market. Little is known about socioeconomic, demographic and smoking-related determinants of the likelihood of using these products among smokers. The aim of this study was to examine these determinants.

METHODS

Data from the 2006-2007 Tobacco Use Supplement to the Current Population Survey was used. We limited the analysis to current smokers (n=40724). Multivariate logistic regression analyses were conducted to estimate the association between covariates and the probability of the use of PREPs.

RESULTS

We found that younger age, lower education, higher nicotine addiction and having an intention to quit are associated with higher likelihood of the use of PREPs. The likelihood of using these products was found to be higher among respondents who are unemployed or have a service, production, sales or farming occupation than those with a professional occupation. Smokers living in the midwest, south or west, were found to have a greater likelihood of the use of PREPs than those living in the northeast.

CONCLUSIONS

Because there is little evidence to suggest that PREPs are less harmful that other tobacco products, their marketing as harm-minimising products should be regulated. Smokers, in particular those who are younger, have a lower socioeconomic status, and are more nicotine-dependent, should be the target of educational programmes that reveal the actual harm of PREPs.

DNA and protein adducts in human tissues resulting from exposure to tobacco smoke

Tobacco smoke contains a variety of genotoxic carcinogens that form adducts with DNA and protein in the tissues of smokers. Not only are these biochemical events relevant to the carcinogenic process, but the detection of adducts provides a means of monitoring exposure to tobacco smoke. Characterization of smoking-related adducts has shed light on the mechanisms of smoking-related diseases and many different types of smoking-derived DNA and protein adducts have been identified. Such approaches also reveal the potential harm of environmental tobacco smoke (ETS) to nonsmokers, infants and children. Because the majority of tobacco-smoke carcinogens are not exclusive to this source of exposure, studies comparing smokers and nonsmokers may be confounded by other environmental sources. Nevertheless, certain DNA and protein adducts have been validated as biomarkers of exposure to tobacco smoke, with continuing applications in the study of ETS exposures, cancer prevention and tobacco product legislation. Our article is a review of the literature on smoking-related adducts in human tissues published since 2002.

Research opportunities related to establishing standards for tobacco products under the Family Smoking Prevention and Tobacco Control Act

INTRODUCTION

This paper was written in response to a request from the U.S. National Cancer Institute. The goal is to discuss some research directions related to establishing tobacco product standards under the Family Smoking Prevention and Tobacco Control Act, which empowers the U.S. Food and Drug Administration to regulate tobacco products. Potential research related to tobacco product ingredients, nicotine, and harmful or potentially harmful constituents of tobacco products is discussed.

DISCUSSION

Ingredients, which are additives, require less attention than nicotine and harmful or potentially harmful constituents. With respect to nicotine, the threshold level in tobacco products below which dependent users will be able to freely stop using the product if they choose to do so is a very important question. Harmful and potentially harmful constituents include various toxicants and carcinogens. An updated list of 72 carcinogens in cigarette smoke is presented. A crucial question is the appropriate levels of toxicants and carcinogens in tobacco products. The use of carcinogen and toxicant biomarkers to determine these levels is discussed.

CONCLUSIONS

The need to establish regulatory standards for added ingredients, nicotine, and other tobacco and tobacco smoke constituents leads to many interesting and potentially highly significant research questions, which urgently need to be addressed.

Smoking cessation program with exercise improves cardiovascular disease biomarkers in sedentary women

BACKGROUND

Several cardiovascular disease (CVD) biomarkers sensitive to tobacco exposure have been identified, but how tobacco use cessation impacts them is less clear. We sought to investigate the effects of a smoking cessation program with an exercise intervention on CVD biomarkers in sedentary women.

METHODS

This is a cohort study on a subsample of a 2×2 factorial randomized controlled trial (RCT) (exercise setting: home vs. facility; level of exercise counseling: prescription only vs. prescription and adherence counseling) conducted January 2004 through December 2007. The analyses were completed in October 2010. In the greater Boston area, 130 sedentary female smokers aged 19-55 completed a 15-week program. All participants received nicotine replacement therapy (transdermal patch) and brief behavioral counseling for 12 weeks. They all received an exercise prescription on a moderate intensity level. All exercise interventions lasted for 15 weeks, from 3 weeks precessation until 12 weeks postcessation. Main outcome measures were selected CVD biomarkers hypothesized to be affected by smoking cessation or exercise measured at baseline and 12 weeks postcessation.

RESULTS

Independent of tobacco abstinence, improvement was seen in inflammation (white blood cells [WBC]), prothrombotic factor (red blood cells [RBC]), and cardiovascular fitness level (maximum oxygen consumption [Vo(2)max]). This suggests that even if complete abstinence is not achieved, reduction in tobacco exposure and increase in exercise can improve the cardiovascular risk profile. A significant decrease was seen for total cholesterol and the total cholesterol high-density lipoprotein cholesterol (HDL-C): ratio only among the abstainers. The heart rate was reduced among all participants, but this decrease was more profound among abstainers. A significant weight gain and body mass index (BMI) increase were observed among abstainers and those who relapsed. We also found an increase in hemoglobin A1c (Hb A1c), although significant only when the groups were combined.

CONCLUSIONS

A smoking cessation intervention including exercise reduced tobacco-induced cardiovascular damage selectively within 3 months.

Is 24h nicotine equivalents a surrogate for smoke exposure based on its relationship with other biomarkers of exposure?

Nicotine and its 5 major metabolites (Nicotine equivalents, NE) may serve as a surrogate biomarker for smoke exposure.

OBJECTIVE

To investigate the relationship between nicotine equivalents (NE) and biomarkers of exposure (BOE) to cigarette smoke.

METHODS

Data from nine controlled studies in 916 adult smokers were used. BOEs to nicotine, NNK, pyrene, acrolein, benzene, 1,3-butadiene and CO were used.

RESULTS

Among all the factors investigated (NE, cigarette type, age, gender, BMI and study), NE was the most statistically significant factor for all biomarker relationships. Weak to moderate relationships (0.32 ≤ R(2)  ≤ 0.65) were found between NE and the BOEs.

CONCLUSIONS

Based on the relationships with BOEs, NE may be considered as a surrogate biomarker of total cigarette smoke exposure.

Quantification of ETS exposure in hospitality workers who have never smoked

BACKGROUND

Environmental Tobacco Smoke (ETS) was classified as human carcinogen (K1) by the German Research Council in 1998. According to epidemiological studies, the relative risk especially for lung cancer might be twice as high in persons who have never smoked but who are in the highest exposure category, for example hospitality workers. In order to implement these results in the German regulations on occupational illnesses, a valid method is needed to retrospectively assess the cumulative ETS exposure in the hospitality environment.

METHODS

A literature-based review was carried out to locate a method that can be used for the German hospitality sector. Studies assessing ETS exposure using biological markers (for example urinary cotinine, DNA adducts) or questionnaires were excluded. Biological markers are not considered relevant as they assess exposure only over the last hours, weeks or months. Self-reported exposure based on questionnaires also does not seem adequate for medico-legal purposes. Therefore, retrospective exposure assessment should be based on mathematical models to approximate past exposure.

RESULTS

For this purpose a validated model developed by Repace and Lowrey was considered appropriate. It offers the possibility of retrospectively assessing exposure with existing parameters (such as environmental dimensions, average number of smokers, ventilation characteristics and duration of exposure). The relative risk of lung cancer can then be estimated based on the individual cumulative exposure of the worker.

CONCLUSION

In conclusion, having adapted it to the German hospitality sector, an existing mathematical model appears to be capable of approximating the cumulative exposure. However, the level of uncertainty of these approximations has to be taken into account, especially for diseases with a long latency period such as lung cancer.

Applying tobacco carcinogen and toxicant biomarkers in product regulation and cancer prevention

Tobacco carcinogen and toxicant biomarkers are metabolites or protein or DNA adducts of specific compounds in tobacco products. Highly reliable analytical methods, based mainly on mass spectrometry, have been developed and applied in large studies of many of these biomarkers. A panel of tobacco carcinogen and toxicant biomarkers is suggested here, and typical values for smokers and nonsmokers are summarized. This panel of biomarkers has potential applications in the new and challenging area of tobacco product regulation and in the development of rational approaches to cancer prevention by establishing carcinogen and toxicant uptake and excretion in people exposed to tobacco products.

Hypotheses and fundamental study design characteristics for evaluating potential reduced-risk tobacco products. Part I: Heuristic

The risk-reducing effect of a potential reduced-risk tobacco product (PRRP) can be investigated conceptually in a long-term, prospective study of disease risks among cigarette smokers who switch to a PRRP and in appropriate comparison groups. Our objective was to provide guidance for establishing the fundamental design characteristics of a study intended to (1) determine if switching to a PRRP reduces the risk of lung cancer (LC) compared with continued cigarette smoking, and (2) compare, using a non-inferiority approach, the reduction in LC risk among smokers who switched to a PRRP to the reduction in risk among smokers who quit smoking entirely. Using standard statistical methods applied to published data on LC incidence after smoking cessation, we show that the sample size and duration required for a study designed to evaluate the potential for LC risk reduction for an already marketed PRRP, compared with continued smoking, varies depending on the LC risk-reducing effectiveness of the PRRP, from a 5-year study with 8000-30,000 subjects to a 15-year study with <5000 to 10,000 subjects. To assess non-inferiority to quitting, the required sample size tends to be about 10 times greater, again depending on the effectiveness of the PRRP.

Lung cancer in never smokers: molecular profiles and therapeutic implications

The majority of lung cancers are caused by long term exposure to the several classes of carcinogens present in tobacco smoke. Although a significant fraction of lung cancers in never smokers may also be attributable to tobacco, many such cancers arise in the absence of detectable tobacco exposure, and may follow a very different cellular and molecular pathway of malignant transformation. Recent studies summarized here suggest that lung cancers arising in never smokers have a distinct natural history, profile of oncogenic mutations, and response to targeted therapy. The majority of molecular analyses of lung cancer have focused on genetic profiling of pathways responsible for metabolism of primary tobacco carcinogens. Limited research has been conducted evaluating familial aggregation and genetic linkage of lung cancer, particularly among never smokers in whom such associations might be expected to be strongest. Data emerging over the past several years show that lung cancers in never smokers are much more likely to carry activating mutations of the epidermal growth factor receptor (EGFR), a key oncogenic factor and direct therapeutic target of several newer anticancer drugs. EGFR mutant lung cancers may represent a distinct class of lung cancers, enriched in the never-smoking population, and less clearly linked to direct tobacco carcinogenesis. These insights followed initial testing and demonstration of efficacy of EGFR-targeted drugs. Focused analysis of molecular carcinogenesis in lung cancers in never smokers is needed, and may provide additional biologic insight with therapeutic implications for lung cancers in both ever smokers and never smokers.

Cigarette filter-based assays as proxies for toxicant exposure and smoking behavior--a literature review

BACKGROUND

Cigarettes are being marketed with filters that differ in composition and design. The filters have different toxicant trapping efficiencies, and smoking stains reflect variations in smoking behavior. Presented herein are the results of a structured literature review that was done to identify cigarette filter-based assays that may serve as proxies for mouth-level exposure and assessing smoking methods.

METHODS

A search of the published scientific literature and internal tobacco company documents from 1954 to 2009 was carried out.

RESULTS

The literature search identified diverse schemes for assessing cigarette filters, including visual inspection and digital imaging of smoked-stained spent filters, and quantitative determinations for total particulate matter (TPM), nicotine, and solanesol. The results also showed that: (a) there are sufficient data to link filter-based chemical measures to standardized smoking machine-measured yields of tar and nicotine; (b) TPM eluted from filters or in chemical digest of filters can be used to estimate the efficiency of the filter for trapping smoke solids; (c) visual and digital inspection of spent filters is useful in finding indicators of variations in smoking behaviors; and (d) there is a correlation between solanesol and nicotine measured in filters and exposure biomarkers in smokers.

CONCLUSIONS

The cigarette filter may prove useful in estimating smoking behaviors such as filter vent blocking and puffing intensity, and may have utility as proxy measures of mouth-level smoke exposure in clinical trials. Additional investigations are needed to compare the different proposed assay schemes and the assay results with measurements of human biomarker assays of smoke exposure.

A pilot randomized study of smokeless tobacco use among smokers not interested in quitting: changes in smoking behavior and readiness to quit

INTRODUCTION

Several prior studies suggest that smokeless tobacco use results in less carcinogenic risk than does cigarette smoking. Whether smokers will use smokeless tobacco is unclear, as is the impact of such use on long-term smoking behavior and cessation. It is equally plausible that smokeless tobacco use among smokers could either (a) increase total tobacco exposure and undermine motivation to quit or (b) decrease overall tobacco exposure, motivate smokers to quit, and enhance cessation. Either outcome is of major public health significance.

METHODS

In this small (N = 31), short-term (2 week) pilot study, smokers uninterested in quitting were randomized to (a) receive Ariva or Stonewall (both spitless and smokeless tobacco lozenges) or (b) continue smoking conventional cigarettes.

RESULTS

Ariva/Stonewall use led to a significant reduction (40%, 95% CI: 24%-55%) in cigarettes per day, no significant increases in total tobacco use (cigarettes + Ariva/Stonewall; p > .05), and significant increases in two measures of readiness to quit, either in the next month (p < .001) or within the next 6 months (p = .04), as well as significant increases in self-efficacy to quit smoking (p < .001). No such changes were found among smokers maintained on conventional cigarettes.

DISCUSSION

These results suggest no deleterious effect on short-term smoking and quitting behavior among smokers who use smokeless tobacco. More broadly, this study suggests a strong need for a large prospective randomized clinical trial to more accurately assess the long-term viability of smokeless tobacco use as a method for cessation induction among unmotivated smokers.

Clinical trials methods for evaluation of potential reduced exposure products

Potential reduced exposure products (PREPs) to tobacco toxicants may have promise in reducing tobacco-related morbidity or mortality or may promote greater harm to individuals or the population. Critical to determining the risks or benefits from these products are valid human clinical trial PREP assessment methods. Such an assessment involves determining the effects of these products on biomarkers of exposure and effect, which serve as proxies for harm, and assessing the potential for consumer uptake and abuse of the product. This article identifies critical methodologic issues associated with PREP assessments, reviews the methods that have been used to assess PREPs, and describes the strengths and limitations of these methods. Additionally, recommendations are provided for clinical trial PREP assessment methods and future research directions in this area based on this review and on the deliberations from a National Cancer Institute sponsored Clinical Trials PREP Methods Workshop.

Reconciling human smoking behavior and machine smoking patterns: implications for understanding smoking behavior and the impact on laboratory studies

BACKGROUND

Recent Food and Drug Administration legislation enables the mandating of product performance standards for cigarette smoke and the evaluation of manufacturers' health claims for modified tobacco products. Laboratory studies used for these evaluations and also for understanding tobacco smoke toxicology use machines to generate smoke. The goal of this review is to critically evaluate methods to assess human smoking behavior and replicate this in the laboratory.

METHODS

Smoking behavior and smoking machine studies were identified using PubMed and publicly available databases for internal tobacco company documents.

RESULTS

The smoking machine was developed to generate smoke to allow for comparing cigarette tar and nicotine yields. The intent was to infer relative human disease risk, but this concept was flawed because humans tailor their smoking to the product, and chemical yields and toxicologic effects change with different smoking profiles. Although smoking machines also allow for mechanistic assessments of smoking-related diseases, the interpretations also are limited. However, available methods to assess how humans puff could be used to provide better laboratory assessments, but these need to be validated. Separately, the contribution of smoke mouth-holding and inhalation to dose need to be assessed, because these parts of smoking are not captured by the smoking machine. Better comparisons of cigarettes might be done by tailoring human puff profiles to the product based on human studies and comparing results across regimens.

CONCLUSIONS

There are major research gaps that limit the use of smoking machine studies for informing tobacco control regulation and mechanistic studies.

Effects of smoking cessation on eight urinary tobacco carcinogen and toxicant biomarkers

We determined the persistence at various times (3, 7, 14, 21, 28, 42, and 56 days) of eight tobacco smoke carcinogen and toxicant biomarkers in the urine of 17 smokers who stopped smoking. The biomarkers were 1-hydroxy-2-(N-acetylcysteinyl)-3-butene (1) and 1-(N-acetylcysteinyl)-2-hydroxy-3-butene (2) [collectively called MHBMA for monohydroxybutyl mercapturic acid] and 1,2-dihydroxy-4-(N-acetylcysteinyl)butane (3) [DHBMA for dihydroxybutyl mercapturic acid], metabolites of 1,3-butadiene; 1-(N-acetylcysteinyl)-propan-3-ol (4, HPMA for 3-hydroxypropyl mercapturic acid), a metabolite of acrolein; 2-(N-acetylcysteinyl)butan-4-ol (5, HBMA for 4-hydroxybut-2-yl mercapturic acid), a metabolite of crotonaldehyde; (N-acetylcysteinyl)benzene (6, SPMA for S-phenyl mercapturic acid), a metabolite of benzene; (N-acetylcysteinyl)ethanol (7, HEMA for 2-hydroxyethyl mercapturic acid), a metabolite of ethylene oxide; 1-hydroxypyrene (8) and its glucuronides (1-HOP), metabolites of pyrene; and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (9) and its glucuronides (total NNAL), a biomarker of exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). These biomarkers represent some of the major carcinogens and toxicants in cigarette smoke: 1,3-butadiene, acrolein, crotonaldehyde, benzene, ethylene oxide, polycyclic aromatic hydrocarbons (PAH), and NNK. With the exception of DHBMA, levels of which did not change after cessation of smoking, all other biomarkers decreased significantly after 3 days of cessation (P < 0.001). The decreases in MHBMA, HPMA, HBMA, SPMA, and HEMA were rapid, nearly reaching their ultimate levels (81-91% reduction) after 3 days. The decrease in total NNAL was gradual, reaching 92% after 42 days, while reduction in 1-HOP was variable among subjects to about 50% of baseline. Since DHBMA did not change upon smoking cessation, there appear to be sources of this metabolite other than 1,3-butadiene. The results of this study demonstrate that the tobacco smoke carcinogen/toxicant biomarkers MHBMA, HPMA, HBMA, SPMA, HEMA, 1-HOP, and NNAL are related to smoking and are good indicators of the impact of smoking on human exposure to 1,3-butadiene, acrolein, crotonaldehyde, benzene, ethylene oxide, PAH, and NNK.

Smokers of menthol and nonmenthol cigarettes exhibit similar levels of biomarkers of smoke exposure

There has been speculation that the addition of menthol to cigarettes may affect the manner in which cigarettes are smoked, potentially influencing smokers' exposures to smoke constituents that have been associated with smoking-related diseases. One hundred twelve male and female smokers participated in a parallel-arm study to determine whether the ad libitum smoking of menthol cigarettes results in differences in smoke constituent exposure biomarkers in blood and urine relative to those smoking nonmenthol cigarettes having similar machine-measured (Federal Trade Commission) yields of approximately 9 to 10 mg "tar." The study subjects were provided cigarettes of their preferred menthol or nonmenthol types prior to two 24-hour study intervals spaced one week apart. Carboxyhemoglobin levels were measured in blood samples drawn at midafternoon following the two 24-hour urine collection periods. Six urinary nicotine metabolites (nicotine, cotinine, trans-3'-hydroxycotinine and respective glucuronides) were determined as measures of nicotine intake, and urinary 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronide were determined to assess exposure to the tobacco-specific nitrosamine 4-(N-nitrosomethylamino)-1-(3-pyridinyl)-1-butanone. Subjects' median blood carboxyhemoglobin values did not differ significantly between the cigarette types. Neither total urinary NNAL nor urinary nicotine equivalents exhibited statistically significant differences between the menthol and nonmenthol cigarette smokers. The present findings indicate that moderately heavy smokers of menthol and nonmenthol cigarettes of similar machine-generated smoke yield exhibit essentially identical levels of biomarkers of smoke constituent exposure. These results are consistent with the substantial majority of epidemiology studies to date that suggest the risks attending the smoking of menthol and nonmenthol cigarettes are similar.

Nicotine gum for pregnant smokers: a randomized controlled trial

OBJECTIVE

To estimate the safety and efficacy of treatment with 2-mg nicotine gum for smoking cessation during pregnancy.

METHODS

Pregnant women who smoked daily received individualized behavioral counseling and random assignment to a 6-week treatment with 2-mg nicotine gum or placebo followed by a 6-week taper period. Women who did not quit smoking were instructed to reduce the number of cigarettes smoked by substituting with gum. Measures of tobacco exposure were obtained throughout the study.

RESULTS

Participants in the nicotine (n = 100) and placebo (n = 94) groups were comparable in age, race/ethnicity, and smoking history. Biochemically validated smoking-cessation rates were not significantly higher with nicotine gum compared with placebo (after 6 weeks of treatment: 13% compared with 9.6%, P=.45; at 32-34 weeks of gestation: 18% compared with 14.9%, P=.56). Using a completer analysis, nicotine gum significantly reduced the number of cigarettes smoked per day (nicotine gum: -5.7 [standard deviation (SD)=6.0]; placebo: -3.5 [SD=5.7], P=.035), and cotinine concentration (nicotine gum: -249 ng/mL [SD=397]; placebo: -112 ng/mL [SD=333]; P=.04). Birth weights were significantly greater with nicotine gum compared with placebo (3,287 g [SD=566] and 2,950 g [SD=653], respectively, P<.001). Gestational age was also greater with nicotine-replacement therapy than with placebo (38.9 weeks [SD=1.7] and 38.0 weeks [SD=3.3], respectively; P=.014).

CONCLUSION

Although nicotine gum did not increase quit rates, use of nicotine gum increased birth weight and gestational age, two key parameters in predicting neonatal wellbeing.

Associations between cigarette smoking and mitochondrial DNA abnormalities in buccal cells

DNA alterations in mitochondria are believed to play a role in carcinogenesis and are found in smoking-related cancers. We sought to replicate earlier findings for the association of smoking with increased mitochondrial DNA (mtDNA) content in buccal cells and further hypothesized that there would be an increased number of somatic mtDNA mutations in smokers. Buccal cells and blood lymphocytes were studied from 42 healthy smokers and 30 non-smokers. Temporal temperature gradient electrophoresis screening and sequencing was used to identify mtDNA mutations. The relative mtDNA content was determined by real-time polymerase chain reaction. Assuming that mtDNA in lymphocytes represents the inherited sequence, it was found that 31% of smokers harbored at least one somatic mtDNA mutation in buccal cells with a total of 39 point mutations and 8 short deletions/insertions. In contrast, only 23% of non-smokers possessed mutations with a total of 10 point mutations and no insertions/deletions detected. mtDNA somatic mutation density was higher in smokers (0.68/10 000 bp per person) than in non-smokers (0.2/10 000 bp per person). There was a statistically significant difference in the pattern of homoplasmy and heteroplasmy mutation changes between smokers and non-smokers. Whereas non-smokers had the most mutations in D-loop region (70%), smokers had mutations in both messenger RNA encoding gene (36%) and D-loop region (49%). The mean ratio of buccal cells to lymphocytes of mtDNA content in smokers was increased (2.81) when compared with non-smokers (0.46). These results indicate that cigarette smoke exposure affects mtDNA in buccal cells of smokers. Additional studies are needed to determine if mitochondrial mutation assays provide new or complementary information for estimating cigarette smoke exposure at the cellular level or as a cancer risk biomarker.

Progress and challenges in selected areas of tobacco carcinogenesis

Tobacco use continues to be a major cause of cancer in the developed world, and despite significant progress in this country in tobacco control, which is driving a decrease in cancer mortality, there are still over 1 billion smokers in the world. This perspective discusses some selected issues in tobacco carcinogenesis focusing on progress during the 20 years of publication of Chemical Research in Toxicology. The topics covered include metabolism and DNA modification by tobacco-specific nitrosamines, tobacco carcinogen biomarkers, an unidentified DNA ethylating agent in cigarette smoke, mutations in the K-RAS and p53 gene in tobacco-induced lung cancer and their possible relationship to specific carcinogens, secondhand smoke and lung cancer, emerging issues in smokeless tobacco use, and a conceptual model for understanding tobacco carcinogenesis. It is hoped that a better understanding of mechanisms of tobacco-induced cancer will lead to new and useful approaches for the prevention of lung cancer and other cancers caused by tobacco use.

Introducing oral tobacco for tobacco harm reduction: what are the main obstacles?

With the number of smokers worldwide currently on the rise, the regular failure of smokers to give up their tobacco addiction, the direct role of smoke (and, to a much lesser extent, nicotine) in most tobacco-related diseases, and the availability of less toxic (but still addictive) oral tobacco products, the use of oral tobacco in lieu of smoking for tobacco harm reduction (HR) merits assessment.

Instead of focusing on the activity itself, HR focuses on the risks related to the activity. Currently, tobacco HR is controversial, generally not discussed, and consequently, poorly evaluated.

In this paper, we try to pinpoint some of the main reasons for this lack of interest or reluctance to carry out or fund this type of research. In this paper we deal with the following issues: the status of nicotine in society, the reluctance of the mainstream anti-tobacco lobby toward the HR approach, the absence of smokers from the debate, the lack of information disseminated to the general population and politicians, the need to protect young people, the role of physicians, the future of HR research, and the role of tobacco companies.

Quantitation of acrolein-derived (3-hydroxypropyl)mercapturic acid in human urine by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry: effects of cigarette smoking

Recently published data suggest that acrolein (1), a toxic but weakly carcinogenic constituent of cigarette smoke, may be involved as a causative factor for the mutations frequently observed in the p53 tumor suppressor gene in lung cancer in smokers. Biomarkers are needed to further assess the possible relationship between acrolein uptake and cancer. In this study, we analyzed (3-hydroxypropyl)mercapturic acid (3-HPMA, 2) in human urine. 3-HPMA is a major metabolite of acrolein in laboratory animals. The method employs [13C3]3-HPMA as an internal standard, with analysis and quantitation by LC-APCI-MS/MS-SRM. Clean, readily quantifiable chromatograms were obtained. The method was accurate and precise and required only 0.1 mL of urine. Median levels of 3-HPMA were significantly higher (2900 pmol/mg of creatinine, N=35) in smokers than in nonsmokers (683 pmol/mg of creatinine, N=21) (P=0.0002). The effect of smoking was further assessed by determining the levels of 3-HPMA before and after a 4 week smoking cessation period. There was a significant 78% decrease in median levels of urinary 3-HPMA after cessation (P<0.0001). The relationship between the levels of urinary 3-HPMA and those of acrolein-derived 1,N2-propanodeoxyguanosine (PdG) adducts in lung was investigated in 14 smokers. There was a significant inverse relationship between urinary 3-HPMA and alpha-hydroxy-PdG (3) but not gamma-hydroxy-PdG (4) or total adduct levels. The results of this study clearly demonstrate that acrolein uptake in smokers is significantly higher than in nonsmokers and underline the need for further investigation of the possible relationship of acrolein uptake to lung cancer.

Quantitation of isoprostane isomers in human urine from smokers and nonsmokers by LC-MS/MS

A simple, rapid liquid chromatography-tandem mass spectrometry method was developed to identify and quantitate in human urine the isoprostanes iPF(2 alpha)-III, 15-epi-iPF(2 alpha)-III, iPF(2 alpha)-VI, and 8,12-iso-iPF(2 alpha)-VI along with the prostaglandin PGF(2 alpha) and 2,3-dinor-iPF(2 alpha)-III, a metabolite of iPF(2 alpha)-III. Assay specificity, linearity, precision, and accuracy met the required criteria for most analytes. The urine sample storage stability and standard solution stability were also tested. The methodology was applied to analyze 24 h urine samples collected from smokers and nonsmokers on controlled diets. The results for iPF(2 alpha)-III obtained by our method were significantly correlated with results by an ELISA, although an approximately 2-fold high bias was observed for the ELISA data. For iPF(2 alpha)-III and its metabolite 2,3-dinor-iPF(2 alpha)-III, smokers had significantly higher concentrations than nonsmokers (513 +/- 275 vs. 294 +/- 104 pg/mg creatinine; 3,030 +/- 1,546 vs. 2,046 +/- 836 pg/mg creatinine, respectively). The concentration of iPF(2 alpha)-VI tended to be higher in smokers than in nonsmokers; however, the increase was not statistically significant in this sample set. Concentrations of the other three isoprostane isomers showed no trends toward differences between smokers and nonsmokers. Among smokers, the daily output of two type VI isoprostanes showed a weak correlation with the amount of tobacco smoke exposure, as determined by urinary excretion of total nicotine equivalents.

Nicotine pharmacokinetics and subjective effects of three potential reduced exposure products, moist snuff and nicotine lozenge

OBJECTIVE

To compare nicotine pharmacokinetics and subjective effects of three new smokeless tobacco potential reduced exposure products (PREPs; Ariva, Revel and Stonewall) with moist snuff (Copenhagen) and medicinal nicotine (Commit lozenge).

METHODS

10 subjects completed a randomised, within-subject, crossover study. Subjects used one product for 30 min at each of the five laboratory sessions. Maximal nicotine concentration (Cmax) was determined and area under the concentration time curve (AUC) was calculated for a 90-min period (during use and 60 min after use). Nicotine craving, withdrawal symptoms and ratings of product effects and liking were measured during product use.

RESULTS

Nicotine AUC and Cmax were higher for Copenhagen than for any other product (p<0.002) and higher for Commit than for either Ariva or Revel (p<0.001). Cmax for Commit was also higher than for Stonewall (p = 0.03). Craving was lowest during use of Copenhagen (p<0.03). Craving during use of Stonewall, Ariva and Commit was lower than during use of Revel (p<0.05). Withdrawal symptom score during use of Copenhagen was lower than during use of Revel (p = 0.009). Copenhagen scores were higher (p<0.005) than all other products in several measures of drug effects and liking (feel good effects, satisfaction, liking and desire for product, and strength of product).

CONCLUSION

The new smokeless tobacco PREPs result in lower nicotine concentrations and equivalent or lower reductions in subjective measures compared with medicinal nicotine. Since health effects of PREPs are largely unknown, medicinal nicotine should be preferentially encouraged for smokers or smokeless tobacco users wishing to switch to lower-risk products.