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

Exposure to polycyclic aromatic hydrocarbons, volatile organic compounds, and tobacco-specific nitrosamines and incidence of esophageal cancer

BACKGROUND

Studying carcinogens in tobacco and nontobacco sources may be key to understanding the pathogenesis and geographic distribution of esophageal cancer.

METHODS

The Golestan Cohort Study has been conducted since 2004 in a region with high rates of esophageal squamous cell carcinoma. For this nested study, the cases comprised of all incident cases by January 1, 2018; controls were matched to the case by age, sex, residence, time in cohort, and tobacco use. We measured urinary concentrations of 33 exposure biomarkers of nicotine, polycyclic aromatic hydrocarbons, volatile organic compounds, and tobacco-specific nitrosamines. We used conditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals for associations between the 90th vs the 10th percentiles of the biomarker concentrations and incident esophageal squamous cell carcinoma.

RESULTS

Among individuals who did not currently use tobacco (148 cases and 163 controls), 2 acrolein metabolites, 2 acrylonitrile metabolites, 1 propylene oxide metabolite, and one 1,3-butadiene metabolite were significantly associated with incident esophageal squamous cell carcinoma (adjusted odds ratios between 1.8 and 4.3). Among tobacco users (57 cases and 63 controls), metabolites of 2 other volatile organic compounds (styrene and xylene) were associated with esophageal squamous cell carcinoma (OR = 6.2 and 9.0, respectively). In tobacco users, 2 tobacco-specific nitrosamines (NNN and N'-Nitrosoanatabine) were also associated with esophageal squamous cell carcinoma. Suggestive associations were seen with some polycyclic aromatic hydrocarbons (especially 2-hydroxynaphthalene) in nonusers of tobacco products and other tobacco-specific nitrosamines in tobacco users.

CONCLUSION

These novel associations based on individual-level data and samples collected many years before cancer diagnosis, from a population without occupational exposure, have important public health implications.

A Randomized Control Study in Healthy Adult Smokers to Assess Reduced Exposure to Selected Cigarette Smoke Constituents in Switching to the Novel Heated Tobacco Product DT3.0a

This was a randomized, controlled, open-label, confinement study to assess change in exposure to selected cigarette smoke constituents in healthy adult cigarette smokers who switched to using a novel heated tobacco product (direct heating tobacco system, platform 3, generation 3, version a [DT3.0a]). Sixty nonmenthol cigarette smokers were randomized into 1 of the 4 study groups in which subjects switched to a nonmenthol type of tobacco stick used with DT3.0a, switched to a nonmenthol tobacco stick used with an in-market heated tobacco product device (THS), continued to smoke nonmenthol cigarettes, or stopped smoking. Furthermore, 30 menthol cigarette smokers were randomized into 1 of the 2 study groups in which subjects switched to a menthol tobacco stick used with DT3.0a (mDT3.0a) or continued to smoke menthol cigarettes. Fifteen biomarkers of exposure to selected harmful and potentially harmful constituents (HPHCs) were measured during the 5-day exposure period, followed by assessment of nicotine pharmacokinetics with the assigned product. Results indicated that switching to DT3.0a, THS, and mDT3.0a showed significant exposure reductions in most of the selected HPHCs as compared to continuing smoking cigarettes, with reductions being similar in magnitude to reductions observed with smoking cessation. For DT3.0a and mDT3.0a, nicotine pharmacokinetic parameters were not remarkably different from those obtained for cigarettes and the THS except that a longer time to maximum concentration was obtained following use of the mDT3.0a. In conclusion, switching from smoking cigarettes to DT3.0a or THS use reduced exposure to most of the selected HPHCs, and no remarkable differences were observed for the measurements obtained from different flavors of DT3.0a stick.

Tobacco Smoke Is a Major Source of Aromatic Amine Exposure in U.S. Adults: 2013-2014 National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

Cigarette smoking increases the risk of cancer, cardiovascular diseases, and premature death. Aromatic amines (AA) are found in cigarette smoke and are well-established human bladder carcinogens.

METHODS

We measured and compared total urinary levels of 1-aminonaphthalene (1AMN), 2-aminonaphthalene (2AMN), and 4-aminobiphenyl (4ABP) in adults who smoked cigarettes exclusively and in adult nonusers of tobacco products from a nationally representative sample of non-institutionalized U.S. population in the 2013-2014 National Health and Nutrition Examination Survey.

RESULTS

Sample-weighted geometric mean concentrations of AAs in adults who smoked cigarettes exclusively compared with adult nonusers were 30 times higher for 1AMN and 4 to 6 times higher for 2AMN and 4ABP. We evaluated the association of tobacco-smoke exposure with urinary AAs using sample-weighted multiple linear regression models to control for age, sex, race/ethnicity, diet, and urinary creatinine. Secondhand smoke exposure status was categorized using serum cotinine (SCOT) among adult nonusers (SCOT ≤ 10 ng/mL). The exposure for adults who smoked cigarettes exclusively (SCOT > 10 ng/mL) was categorized on the basis of the average number of self-reported cigarettes smoked per day (CPD) in the five days prior to urine collection. The regression models show AAs concentration increased with increasing CPD (P < 0.001). Dietary-intake variables derived from the 24-hours recall questionnaire were not consistently significant predictors of urinary AAs.

CONCLUSIONS

This is the first characterized total urinary AA concentrations of the U.S. adult non-institutionalized population. Our analyses show that smoking status is a major contributor to AA exposures.

IMPACT

These data provide a crucial baseline for exposure to three AAs in U.S. non-institutionalized adults.

Assessment of biomarkers of exposure and potential harm, and physiological and subjective health measures in exclusive users of nicotine pouches and current, former and never smokers

Background: Oral nicotine pouches (NPs) are smokeless, tobacco-free products that have a potential role in tobacco harm reduction strategies.Methods: In a cross-sectional study in Sweden/Denmark, several recognised biomarkers of potential harm (BoPHs) linked to smoking-related diseases/their initiating biological processes, and biomarkers of exposure (BoEs) to tobacco/tobacco smoke toxicants were compared among exclusive adult users of Velo NPs and current/former/never smokers. Over 24 h, participants used their usual product (Velo NP or cigarette) as normal, and BoEs/BoPHs were assessed via blood/24-h urine/exhaled breath/physiological assessments.Results: Among the primary endpoints, total NNAL (16.9 ± 29.47 vs 187.4 ± 228.93 pg/24 h), white blood cell count (5.59 ± 1.223 vs 6.90 ± 1.758 × 10⁹/L), and COHb (4.36 ± 0.525 vs 8.03 ± 2.173% saturation) were significantly lower among Velo users than among smokers (91%, 19% and 46% lower, respectively, all P < 0.0001), while fractional exhaled NO, previously shown to be lower in smokers, was significantly higher (23.18 ± 17.909 vs 11.20 ± 6.980 ppb) among Velo users (107% higher, P < 0.0001). Furthermore, sICAM-1 tended to be lower (185.9 ± 42.88 vs 204.5 ± 64.85 ng/mL) among Velo users than smokers (9% lower). Several secondary endpoints, including six BoEs (3-HPMA (246.7 ± 91.07 vs 1165.7 ± 718.35 μg/24 h), 3-OH-B[a]P (82.4 ± 217.58 vs 258.3 ± 190.20 pg/24 h), HMPMA (135.1 ± 77.85 vs 368.8 ± 183.15 μg/24 h), MHBMA (0.22 ± 0.166 vs 3.39 ± 2.943 μg/24 h), S-PMA (0.10 ± 0.059 vs 3.53 ± 2.736 µg/24 h) and total NNN (7.5 ± 24.84 vs 9.7 ± 5.93 ng/24 h)), were significantly lower among Velo users (78.8%, 68.1%, 63.4%, 93.5%, 97.2% and 22.7% lower, respectively, P < 0.0001-0.0011), while total nicotine equivalents was significantly higher among Velo users (22.6 ± 12.69 vs 12.1 ± 7.92 mg/24 h, P < 0.0001), although Velo user levels are comparable to those previously reported among oral tobacco users, and Velo user and smoker mean levels were similar in Denmark.Conclusion: As compared with smokers, exclusive users of Velo NPs have significantly less exposure to tobacco toxicants and more favourable BoPHs associated with initiating biological processes of smoking-related diseases.International Standard Registered Clinical Trial number: ISRCTN16988167.

Part three: a randomized study to assess biomarker changes in cigarette smokers switched to Vuse Solo or Abstinence

Biomarkers of exposure (BoE) can help evaluate exposure to combustion-related, tobacco-specific toxicants after smokers switch from cigarettes to potentially less-harmful products like electronic nicotine delivery systems (ENDS). This paper reports data for one (Vuse Solo Original) of three products evaluated in a randomized, controlled, confinement study of BoE in smokers switched to ENDS. Subjects smoked their usual brand cigarette ad libitum for two days, then were randomized to one of three ENDS for a 7-day ad libitum use period, or to smoking abstinence. Thirteen BoE were assessed at baseline and Day 5, and percent change in mean values for each BoE was calculated. Biomarkers of potential harm (BoPH) linked to oxidative stress, platelet activation, and inflammation were also assessed. Levels decreased among subjects randomized to Vuse Solo versus Abstinence, respectively, for the following BoE: 42-96% versus 52-97% (non-nicotine constituents); 51% versus 55% (blood carboxyhemoglobin); and 29% versus 96% (nicotine exposure). Significant decreases were observed in three BoPH: leukotriene E4, 11-dehydro-thromboxane B2, and 2,3-dinor thromboxane B2 on Day 7 in the Vuse Solo and Abstinence groups. These findings show that ENDS use results in substantially reduced exposure to toxicants compared to smoking, which may lead to reduced biological effects.

Assessment of the exposure to selected smoke constituents in adult smokers using in-market heated tobacco products: a randomized, controlled study

The objectives of this clinical study were to demonstrate a reduction in exposure to selected harmful and potentially harmful constituents (HPHCs) in Japanese healthy adult smokers who switched to four in-market heated tobacco products. Eighty-nine smokers were randomly assigned for five days to one of six study groups: four groups who switched to one of the commercially available heated tobacco products; a group who continued to smoke their own brand of combustible cigarettes (CC); or a group who stopped smoking (SS). Fifteen biomarkers of exposure (BoE) to 14 HPHCs and pyrene were measured at baseline, Day 3 and Day 5 in 24 h urine and breath, under clinical confinement. Product consumption, nicotine uptake and subjective effects were also measured before and after product switching. On Day 5, significant reductions in most BoE relative to the CC group were observed after switching to heated tobacco products. No changes in BoE were observed between baseline and Day 5 in the CC group. Significantly, the magnitude of the reduction in exposure to most of the selected HPHCs observed in the heated tobacco product groups was close to that observed in the SS group.

Exposure of Mice to Thirdhand Smoke Modulates In Vitro and In Vivo Platelet Responses

Smoking is a risk factor for a variety of deleterious conditions, such as cancer, respiratory disease and cardiovascular disease. Thrombosis is an important and common aspect of several cardiovascular disease states, whose risk is known to be increased by both first- and secondhand smoke. More recently, the residual cigarette smoke that persists after someone has smoked (referred to as thirdhand smoke or THS) has been gaining more attention, since it has been shown that it also negatively affects health. Indeed, we have previously shown that 6-month exposure to THS increases the risk of thrombogenesis. However, neither the time-dependence of THS-induced thrombus formation, nor its sex dependence have been investigated. Thus, in the present study, we investigated these issues in the context of a shorter exposure to THS, specifically 3 months, in male and female mice. We show that the platelets from 3-month THS-exposed mice exhibited enhanced activation by agonists. Moreover, we also show that mice of both sexes exposed to THS have decreased tail bleeding as well as decreased thrombus occlusion time. In terms of the role of sex, intersex disparities in thrombus development and hemostasis as well as in platelet aggregation were, interestingly, observed. Together, our findings show that exposing mice to THS for 3 months is sufficient to predispose them to thrombosis; which seems to be driven, at least in part, by an increased activity in platelets, and that it does not manifest equally in both sexes.

Assessment of the Exposure to Tobacco-Specific Nitrosamines and Minor Tobacco Alkaloids in Users of Various Tobacco/Nicotine Products

Tobacco-specific nitrosamines (TSNAs), in particular, the human carcinogens 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN), are important toxicants in tobacco and also (as contaminants) in nicotine products. In a clinical study comprising a period of 74 h under confinement, we investigated the exposure to NNK, NNN, N'-nitrosoanabasine (NAB), and N'-nitrosoanatabine (NAT) as well as to the minor tobacco alkaloids anabasine (AB) and anatabine (AT) by measuring suitable biomarkers in habitual users of combustible cigarettes (CCs), electronic cigarettes (ECs), heated tobacco products (HTPs), oral tobacco (OT), and nicotine replacement therapy products (NRTs). Non-users (NU) of any tobacco/nicotine products served as the (negative) control group. Smokers exhibited the highest levels for all biomarkers measured, except for AB in urine, which was found to be highest in OT users. Somewhat elevated levels compared to NU, EC, and NRT groups were also observed in the users of HTPs. In the users of tobacco-containing products (CC, HTP, and OT), most frequently the biomarkers significantly correlated with the dose markers such as daily consumption, urinary nicotine equivalents (Nequ), and plasma cotinine (CotP). In conclusion, except for smokers (CC) and OT users, exposure of users of ECs, HTPs, and NRTs to TSNAs as well as the minor tobacco alkaloids AB and AT is marginal and statistically not distinguishable from that of NU. Finally, our results for NNN in the saliva provide preliminary evidence for the formation of NNN from the precursor nornicotine in the presence of thiocyanate as a catalyst. The latter hypothesis requires experimental verification.

Reductions in biomarkers of exposure to selected harmful and potentially harmful constituents following exclusive and partial switching from combustible cigarettes to myblu™ electronic nicotine delivery systems (ENDS)

Electronic nicotine delivery systems (ENDS) offer adult combustible cigarette smokers an alternative, potentially reduced harm, mode of nicotine delivery, attributed to fewer and reduced levels of harmful and potentially harmful constituents (HPHCs) in their aerosols compared to cigarette smoke. These two identical, randomised, open label, two-part studies aimed to compare levels of 15 biomarkers of exposure (BoE) to selected HPHCs associated with tobacco smoking in healthy US adult smoker subjects (n = 72). Following 9 days of exclusive use of a range of allocated myblu™ ENDS variants, subjects' levels of 14 non-nicotine BoE were substantially reduced compared to baseline values (combustible cigarette use), in the range of 46-97%. BoE reductions were sustained in subjects who continued myblu use exclusively (n = 25) for a further 5 days, and returned to near baseline levels in subjects who returned to exclusive combustible cigarette use (n = 21). Dual users (n = 24) demonstrated reductions in BoE to a lesser extent than with exclusive myblu use. Measured nicotine equivalents did not significantly change throughout the study. These data suggest exclusive use of ENDS provides adult smokers seeking an alternative to combustible cigarettes with substantial reductions in HPHC exposures whilst achieving satisfying levels of nicotine delivery. Dual use involving substitution of cigarettes may also provide some of this advantage, but to lesser extent. Overall, the data contribute to the weight of evidence that ENDS are an important tool in tobacco harm reduction for adult smokers unwilling to or uninterested in quitting smoking. Study 1: NCT04430634, study 2: NCT04429932, clinicaltrials.gov (10-06-2020).

Improving on estimates of the potential relative harm to health from using modern ENDS (vaping) compared to tobacco smoking

BACKGROUND

Although the harm to health from electronic nicotine delivery systems (ENDS) compared to smoked tobacco remains highly uncertain, society and governments still need to know the likely range of the relative harm to inform regulatory policies for ENDS and smoking.

METHODS

We identified biomarkers with specificity of association with different disease groupings e.g., volatile organic compound (VOCs) for chronic obstructive pulmonary disease; and tobacco-specific N´-nitrosamines (TSNAs) and polycyclic aromatic hydrocarbons (PAHs) for all cancers. We conducted a review of recent studies (post January 2017) that compared these biomarkers between people exclusively using ENDS and those exclusively smoking tobacco. The percentage differences in these biomarkers, weighted by study size and adjusted for acrolein from other sources, were used as a proxy for the assumed percentage difference in disease harm between ENDS and smoking. These relative differences were applied to previously modelled estimates of smoking-related health loss (in health-adjusted life-years; HALYs).

RESULTS

The respective relative biomarker levels (ENDS vs smoking) were: 28% for respiratory diseases (five results, three studies); 42% for cancers (five results, four studies); and 35% for cardiovascular (seven results, four studies). When integrated with the HALY impacts by disease, the overall harm to health from ENDS was estimated to be 33% that of smoking.

CONCLUSIONS

This analysis, suggests that the use of modern ENDS devices (vaping) could be a third as harmful to health as smoking in a high-income country setting. But this estimate is based on a limited number of biomarker studies and is best be considered a likely upper level of ENDS risk given potential biases in our method (i.e., the biomarkers used being correlated with more unaccounted for toxicants in smoking compared to with using ENDS).

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.

Identification of biomarkers specific to five different nicotine product user groups: Study protocol of a controlled clinical trial

Background

Assessing biomarker profiles in various body fluids is of large value to discern between the sole use of nicotine products. In particular, the assessment of the product compliance is required for long-term clinical studies. The objective of this study was the identification of biomarkers and biomarker patterns in body fluids, to distinguish between combustibles, heated tobacco products, electronic cigarettes, oral tobacco and oral/dermal nicotine products used for nicotine replacement therapy (NRT), as well as a control group of non-users.

Methods

A controlled, single-center study was conducted with 60 healthy subjects, divided into 6 groups (5 nicotine product user groups and one non-user group) based on their sole use of the products of choice. The subjects were confined for 76 h, during which, free and uncontrolled use of the products was provided. Sample collections were performed according to the study time schedule provided in Table 2. The primary outcome will be validated through analysis of the collected biospecimens (urine, blood, saliva, exhaled breath and exhaled breath condensate) by means of untargeted omics approaches (i.e. exposomics, breathomics and adductomics). Secondary outcome will include established biomarker quantification methods to allow for the identification of typical biomarker patterns. Statistical analysis tools will be used to specifically discriminate different product use categories.

Results/Conclusions

The clinical trial was successfully completed in May 2020, resulting in sample management and preparations for the quantitative and qualitative analyses. This work will serve as a solid basis to discern between biomarker profiles of different nicotine product user groups. The knowledge collected during this research will be required to develop prototype diagnostic tools that can reliably assess the differences and evaluate possible health risks of various nicotine products.

A randomized controlled study in healthy participants to explore the exposure continuum when smokers switch to a tobacco heating product or an E-cigarette relative to cessation

Background

Cigarette smoking is associated with a number of diseases, such as cancer and cardiovascular diseases. Recently, there has been an increase in the use of electronic cigarettes (ECs) and tobacco-heating products (THPs) as an alternative to cigarettes, which may reduce the health burden associated with smoking. However, an exposure continuum when smokers switch to ECs or THPs compared to complete smoking cessation is not well established.

Methods

148 healthy smokers were randomized to either continue smoking cigarettes, switch to using the glo THP or a prototype EC, or completely quit any nicotine or tobacco product use for 5 days, after a 2-day baseline period. During this study breath and 24-h urine samples were collected for Biomarker of Exposure (BoE) analysis.

Results

After a 5-day switching period BoE levels showed a substantial significant decrease in levels from baseline in the groups using the glo THP, the prototype EC, and having quit all nicotine and tobacco use. On an exposure continuum, smokers who completely quit nicotine had the lowest levels of assessed BoEs, followed by those who switched to the EC and then those who switched to glo THP use. Participants who continued to smoke had the highest levels of BoEs.

Conclusions

THP or EC use over a 5-day period resulted in significant reductions in exposure to smoke toxicants, in some cases to levels similar to those for nicotine cessation. These results show that on an exposure continuum, nicotine cessation gives the greatest reduction in exposure to tobacco smoke toxicants, closely followed by the EC and the glo THP. These significant reductions in exposure to toxicants suggest that the glo THP and EC have the potential to be Reduced Risk Products.

Study Registration

ISRCTN80651909.

Changes in Biomarkers of Exposure on Switching From a Conventional Cigarette to the glo Tobacco Heating Product: A Randomized, Controlled Ambulatory Study

Introduction

Tobacco heating products (THPs) generate lower machine yields of toxicants compared to those found in conventional cigarette smoke. During use, these products are likely to expose users to lower levels of particulate matter and harmful and potentially harmful compounds compared with smoking cigarettes.

Aims and Methods

This randomized, controlled study is investigating whether biomarkers of exposure (BoE) to smoke toxicants are reduced when smokers switch from smoking cigarettes to using the glo THP in a naturalistic, ambulatory setting. Control groups include smokers who are abstaining from cigarette smoking and never-smokers. At a baseline study visit, 24-hour urine samples and spot blood samples were taken for BoE analysis, and exhaled carbon monoxide was also measured. N-(2-cyanoethyl) valine (CEVal) was used as a marker of compliance in subjects asked to refrain from combustible cigarette smoking. Subjects are being followed up at periodic intervals for 360 days; this article presents data following a planned interim analysis at day 90.

Results

In continuing smokers, BoE remained stable between baseline (day 1) and day 90. In both per-protocol and CEVal-compliant analysis populations, reductions in BoE were observed in subjects switching to using glo or undergoing smoking cessation. These reductions were statistically significant for a number of BoE when switching to glo was compared with continued smoking. Furthermore, in both populations, reductions observed in subjects switching to using glo were comparable to those seen with smoking cessation and were also to levels similar to those seen in never-smokers.

Conclusion

glo is a reduced-exposure tobacco product.

Implications

This clinical study builds on a previous 5-day confinement study and demonstrates that when smokers switched from smoking combustible cigarettes to using the glo THP in a naturalistic, ambulatory setting, their exposure to tobacco smoke toxicants was significantly decreased. For most BoE examined, this was to the same extent as that seen when a control group of smokers ceased cigarette smoking, or even to levels seen in never-smoker controls. This indicates that glo is a reduced-exposure product with the potential to be a reduced-risk tobacco product, when used by smokers whose cigarette consumption is displaced completely.

Clinical trial registration

ISRCTN81075760.

Use of toenail-bounded heavy metals to characterize occupational exposure and oxidative stress in workers of waterpipe/cigarette cafés

Tobacco smoke is known for releasing metals in indoor air of waterpipe/cigarette cafés. However, the worker exposure to metals, and its association with oxidative stress in these cafés are still unclear. To this end, 54 workers and 38 customers from waterpipe/cigarette cafés (the exposed group), 30 workers from non-smoking cafés (the control group 1 (CG_1)) and 32 individuals from the general population (the control group 2 (CG_2)) were selected and toenails samples were then taken from them. Our findings revealed a significant difference in terms of toenail-bounded metal levels between the exposure and control groups (CG_1 and CG_2) (Mann-Whitney U test, Pvalue < 0.05). This study has also indicated that "type of tobacco" could be considered as a predictor for toenail-bounded heavy metals. Furthermore, our research's results suggest that toenail-bounded heavy metals are positively and significantly correlated with urinary levels of 8- hydroxy-2'-deoxyguanosine (8-OHdG, as a biomarker for the degradation of deoxyribonucleic acid (DNA) oxidative stress). Therefore, it can be concluded that workers of waterpipe/cigarette cafés are at high risks of adverse health of DNA oxidative degradation.

Systematic review of biomarker findings from clinical studies of electronic cigarettes and heated tobacco products

BACKGROUND

Worldwide adoption of electronic cigarettes (e-cigarettes) and heated tobacco products (HTPs) has increased exponentially over the past decade. These products have been proposed as non-combustible alternatives to traditional tobacco products such as cigarettes and may thus reduce the negative health consequences associated with tobacco smoke. However, the overall health impact and safety of using these products remains unclear. This review seeks to provide an updated summary of available evidence on changes to levels of tobacco-related biomarkers to aid the overall assessment of the consequences of using e-cigarettes and HTPs.

METHODS

A systematic review was conducted through major databases (Medline/PubMed, Scopus, EMBASE) searching for articles directly comparing biomarker levels in humans using e-cigarettes or HTPs and those using combustible cigarettes. We included peer reviewed articles with comparative or longitudinal design and extracted key information for our purpose (type of population, demographics, biomarkers measurements, and health effects). An initial qualitative analysis was performed followed by a summary of findings.

RESULTS

A total of 44 studies were included from initial citations. The vast majority of the literature reported reductions in levels of biomarkers of tobacco smoke exposure (BOE), especially nicotine, MHBMA, 3-HPMA, S-PMA, 1-OHP and NNAL, when using e-cigarettes and HTPs compared to combustible cigarettes. There was a slight tendency toward a larger reduction in these biomarkers levels with the use of e-cigarettes, although direct comparisons between e-cigarettes and HTPs were lacking. There was also a trend toward positive changes in levels of biomarkers of biological effect (BOBE) with the use of e-cigarettes and HTPs.

CONCLUSIONS

A comparison of levels of biomarkers of tobacco-related exposure collected in clinical studies revealed that the use of e-cigarettes and HTPs could lead to a significant reduction in exposure to harmful substances compared to combusted cigarettes. In tandem, the health status of e-cigarettes and HTP users, indexed by levels of biomarkers of biological effect showed potential for improvement compared to smoking. However, larger and longer-term population-based studies are needed to further clarify these findings.

Acrolein and other toxicant exposures in relation to cardiovascular disease among marijuana and tobacco smokers in a longitudinal cohort of HIV-positive and negative adults

BACKGROUND

Marijuana smoke contains some of the same toxicants present in tobacco smoke. Marijuana smoking is prevalent among HIV+ individuals, but few studies have characterized smoke-related toxicants or associated health outcomes in exclusive marijuana users.

METHODS

This longitudinal study included 245 participants over age 40 (76% HIV+). 33 plasma and 28 urine metabolites of nicotine, ∆-9-trans-tetrahydrocannabinol, polycyclic aromatic hydrocarbons, and volatile organic compounds were assayed by liquid or gas chromatography/mass spectrometry. Exposures and health outcomes were assessed from surveys and medical records.

FINDINGS

At baseline, 18% of participants were marijuana-only smokers, 20% tobacco-only smokers, and 24% dual marijuana-tobacco smokers (median (IQR) age 53 (47-60) years, 78% male, 54% white race). Marijuana smoking was independently associated with elevated plasma naphthalenes, 2-hydroxyfluorene sulfate, 4-vinylphenol sulfate, and o-cresol sulfate (p<0·05) and urine acrylonitrile and acrylamide metabolites (p<0·05), but levels were lower than those associated with tobacco smoking. Acrolein metabolite N-Acetyl-S-(3-hydroxypropyl)-l-cysteine (3HPMA) was significantly elevated in plasma and urine in tobacco-only and dual but not marijuana-only smokers, and correlated with nicotine metabolites (p<0·05). The highest tertile of 3HPMA was associated with increased cardiovascular disease diagnoses independent of tobacco smoking, traditional risk factors, and HIV status (odds ratio [95% CI] 3·34 [1·31-8·57]; p = 0·012).

INTERPRETATION

Smoke-related toxicants, including acrylonitrile and acrylamide metabolites, are detectable in exclusive marijuana smokers, but exposures are lower compared with tobacco or dual smokers. Acrolein exposure is increased by tobacco smoking but not exclusive marijuana smoking in HIV+ and HIV- adults, and contributes to cardiovascular disease in tobacco smokers.

FUNDING

U.S. NIH.

The association between urinary levels of 1,3-butadiene metabolites, cardiovascular risk factors, microparticles, and oxidative stress products in adolescents and young adults

1,3-Butadiene (BD) is a synthetic colorless gas used in the production of synthetic rubber and polymers. Exposure to BD has been reported to increase oxidative stress and accelerate atherosclerosis in vitro and in animal studies. In occupational studies, BD exposure has been linked to cardiovascular disease (CVD). However, no previous research has been reported on whether BD exposure is associated with CVD risk factors and oxidative stress in the general population. We recruited 853 young participants to study the correlation between urinary levels of the BD metabolite, N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), CVD risk factors, serum levels of endothelial microparticles and platelet microparticles, and the urinary levels of 8-hydroxydeoxyguanosine (8-OHdG). The results showed the DHBMA levels were positively correlated with low-density lipoprotein-C, carotid intima-media thickness (CIMT), CD31+/CD42a - counts (endothelial apoptosis markers), and urinary 8-OHdG levels. Moreover, DHBMA levels were negatively correlated with CD62 P counts (platelet activation marker). The correlation between DHBMA, CIMT, and 8-OHdG was more evident when the levels of CD31+/CD42a - or CD62 P were above 50%. In conclusion, we reported that the urinary levels of DHBMA were associated with the lipid profile, CIMT, microparticles, and marker of oxidative stress in this young population. Future studies on BD exposure and atherosclerosis are needed.

Biomarkers of Tobacco Exposure Decrease After Smokers Switch to an E-Cigarette or Nicotine Gum

Introduction

The aerosol composition of electronic cigarettes (ECs) suggests that exposure to toxicants during use is greatly reduced compared to exposure from combustible cigarettes (CCs).

Methods

This randomized, parallel-group, clinical study enrolled smokers to switch to Vuse Solo (VS) Digital Vapor Cigarettes (Original or Menthol) or Nicorette 4 mg nicotine gum (NG) in a controlled setting. Subjects who smoked CCs ad libitum for 2 days during a baseline period were then randomized to ad libitum use of either VS or NG for 5 days. Biomarkers of 23 toxicants were measured in 24-hour urine samples and blood collected at baseline and following product switch.

Results

A total of 153 subjects completed the study. Total nicotine equivalents decreased in all groups, but higher levels were observed in the VS groups compared to the NG groups, with decreases of 38% and 60%–67%, respectively. All other biomarkers were significantly decreased in subjects switched to VS, and the magnitude of biomarker decreases was similar to subjects switched to NG. Decreases ranged from 30% to greater than 85% for constituents such as benzene and acrylonitrile.

Conclusions

These results indicate that exposure to toxicants when using VS is significantly reduced compared to CC smoking, and these reductions are similar to those observed with use of NG. Although statistically significantly decreased, nicotine exposure is maintained closer to CC smoking with VS use compared to NG use. This research suggests that use of VS exposes consumers to fewer and lower levels of smoke toxicants than CCs while still providing nicotine to the consumer.

Implications

This is the first study to report changes in nicotine delivery and biomarkers of tobacco exposure following a short-term product switch from CCs to either an EC or NG in a controlled environment. The study shows that nicotine exposure decreased in both groups but was maintained closer to CC smoking with the EC groups. Biomarkers of tobacco combustion decreased to similar levels in both EC and gum groups.

Comparison of Urinary Biomarkers of Exposure in Humans Using Electronic Cigarettes, Combustible Cigarettes, and Smokeless Tobacco

BACKGROUND

Cigarette smoking is associated with an increase in cardiovascular disease risk, attributable in part to reactive volatile organic chemicals (VOCs). However, little is known about the extent of VOC exposure due to the use of other tobacco products.

METHODS

We recruited 48 healthy, tobacco users in four groups: cigarette, smokeless tobacco, occasional users of first generation e-cigarette and e-cigarette menthol and 12 healthy nontobacco users. After abstaining for 48 h, tobacco users used an assigned product. Urine was collected at baseline followed by five collections over a 3-h period to measure urinary metabolites of VOCs, nicotine, and tobacco alkaloids.

RESULTS

Urinary levels of nicotine were ≃2-fold lower in occasional e-cigarette and smokeless tobacco users than in the cigarette smokers; cotinine and 3-hydroxycotinine levels were similar in all groups. Compared with nontobacco users, e-cigarette users had higher levels of urinary metabolites of xylene, cyanide, styrene, ethylbenzene, and benzene at baseline and elevated urinary levels of metabolites of xylene, N,N-dimethylformamide, and acrylonitrile after e-cigarette use. Metabolites of acrolein, crotonaldehyde, and 1,3-butadiene were significantly higher in smokers than in users of other products or nontobacco users. VOC metabolite levels in smokeless tobacco group were comparable to those found in nonusers with the exception of xylene metabolite-2-methylhippuric acid (2MHA), which was almost three fold higher than in nontobacco users.

CONCLUSIONS

Smoking results in exposure to a range of VOCs at concentrations higher than those observed with other products, and first generation e-cigarette use is associated with elevated levels of N,N-dimethylformamide and xylene metabolites.

IMPLICATIONS

This study shows that occasional users of first generation e-cigarettes have lower levels of nicotine exposure than the users of combustible cigarettes. Compared with combustible cigarettes, e-cigarettes, and smokeless tobacco products deliver lower levels of most VOCs, with the exception of xylene, N,N-dimethylformamide, and acrylonitrile, whose metabolite levels were higher in the urine of e-cigarette users than nontobacco users. Absence of anatabine in the urine of e-cigarette users suggests that measuring urinary levels of this alkaloid may be useful in distinguishing between users of e-cigarettes and combustible cigarettes. However, these results have to be validated in a larger cohortcomprised of users of e-cigarettes of multiple brands.

Tobacco Consumption and Toxicant Exposure of Cigarette Smokers Using Electronic Cigarettes

Background

There is considerable debate about the benefits and risks of electronic cigarettes (ECs). To better understand the risk-benefit ratio of ECs, more information is needed about net nicotine consumption and toxicant exposure of cigarette smokers switching to ECs.

Methods

Forty cigarette smokers (≥1 year of smoking) interested in switching to ECs but not necessarily quitting smoking were enrolled in a 4-week observational study and provided an e-Go C non-variable battery and refillable atomizers and choice of eight flavors in 12 or 24 mg nicotine dosage. Measurement of urinary cotinine (metabolite of nicotine), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL; a pulmonary carcinogen), and eight volatile organic compounds (VOCs) that are toxic tobacco smoke constituents was conducted at baseline and week 4.

Results

All participants with follow-up data (92.5%) reported using the study EC. Of the 40 smokers, 16 reported no cigarettes at week 2 (40%) and six continued to report no cigarettes at week 4 (15%). Change in nicotine intake over the 4 weeks was non-significant (p = .90). Carbon monoxide (p < .001), NNAL (p < .01) and metabolites of benzene (p < .01) and acrylonitrile (p = .001) were significantly decreased in the study sample. Smokers switching exclusively to ECs for at least half of the study period demonstrated significant reductions in metabolites of ethylene oxide (p = .03) and acrylamide (p < .01).

Conclusion

Smokers using ECs over 4 weeks maintained cotinine levels and experienced significant reductions in carbon monoxide, NNAL, and two out of eight measured VOC metabolites. Those who switched exclusively to ECs for at least half of the study period significantly reduced two additional VOCs.

Implications

This study extends current literature by measuring change in smoking dependence and disease-associated biomarkers, NNAL and a panel of eight common VOCs that are toxic tobacco smoke constituents in smokers who switch to ECs. The findings support the idea of harm reduction, however some levels of toxicant exposure are still of clinical concern, particularly for dual users. Extrapolation of these results must be careful to separate the different toxic exposure results for exclusive switchers versus dual cigarette + EC users, and not to equate harm reduction with the idea that using ECs is harmless.

Measuring e-cigarette addiction among adolescents

BACKGROUND AND OBJECTIVES

With high rates of use and uncertain consequences, valid electronic cigarette (e-cigarette) use frequency and addiction measures for adolescents are needed. This cross-sectional study examined correlations for multiple measures of adolescent e-cigarette use with nicotine exposure quantified with salivary cotinine levels.

METHODS

Adolescents (N=173, age 13-18) who reported past-month e-cigarette use were recruited from the San Francisco Bay Area. Participants self-reported: (1) days of e-cigarette use in a typical month, (2) number of e-cigarette sessions in a typical day (sessions per day; SPD) and the (3) E-Cigarette Addiction Severity Index (EASI). Participants also completed the 10-item Penn State Electronic Cigarette Dependence Index (ECDI), which we examined in full and as a 2-item Heaviness of Vaping Index (HVI; the sum of the ECDI items on use frequency and time to first vaping on wakening). Sessions per month (SPM) were calculated using days per month and SPD. Cotinine levels, SPD and SPM were log-transformed.

RESULTS

Among frequency measures, SPM correlated most strongly with cotinine (r=0.59), followed closely by days per month (r=0.58) and SPD (r=0.57), p<0.001. Among dependence measures, the EASI correlated most strongly with cotinine (r=0.51), closely followed by the ECDI and HVI (r's=0.50), all p's<0.001.

CONCLUSIONS

Adolescents' reports of frequency of e-cigarette use and degree of addiction correlated significantly with cotinine as a biomarker of nicotine exposure. We recommend the EASI and days per month as brief general measures. SPM and the ECDI are more extensive measures that may yield a more nuanced understanding of use.

Time to First Cigarette and the Risk of Hypertension: A Nationwide Representative Study in Korea

BACKGROUND

Although previous studies have explored the effect of smoking on blood pressure, little is still known about the role of time to first cigarette (TTFC)-an indicator of nicotine dependence-in hypertension. Therefore, we evaluated this association using representative nationwide data.

METHODS

Current daily smokers (N = 941; aged 19-79 years) who participated in the 7th version of the Korea National Health and Nutrition Examination Survey I (2016) were included. We categorized participants into 4 groups according to their TTFC. Furthermore, we categorized participants into hypertensive and nonhypertensive groups based on whether they were taking antihypertensive medications or had high blood pressure (≥140/90 mm Hg). The association of daily TTFC and hypertension was examined without adjusting for any covariates; after adjusting for smoking behaviors; and after adjusting for demographic characteristics, socioeconomic status, health-related behaviors, and comorbidities.

RESULTS

In the fully adjusted weighted regression analysis, participants reporting TTFC ≤ 5 minutes (vs. >60 minutes) had roughly twice the odds of having hypertension (95% confidence interval [CI] = 1.07-4.16) and the adjusted odds ratios compared with TTFC of >60 minutes were 1.53 (95% CI = 0.81-2.86) for 6-30 minutes and 1.31 (95% CI = 0.68-2.50) for 31-60 minutes (Ptrend = 0.03).

CONCLUSIONS

Hypertension risk increases with shorter TTFC. Especially, TTFC of ≤5 minutes may prove valuable in assessing the risk of hypertension. Screening smokers based on their TTFC might be useful in assessing their risk of hypertension and smoking cessation programs.

Biomarkers of Exposure to Secondhand and Thirdhand Tobacco Smoke: Recent Advances and Future Perspectives

Smoking is the leading preventable disease worldwide and passive smoking is estimated to be the cause of about 1.0% of worldwide mortality. The determination of tobacco smoke biomarkers in human biological matrices is key to assess the health effects related to the exposure to environmental tobacco smoke. The biomonitoring of cotinine, the main nicotine metabolite, in human biofluids-including urine, serum or saliva-has been extensively used to assess this exposure. However, the simultaneous determination of cotinine together with other tobacco biomarkers and the selection of alternative biological matrices, such as hair, skin or exhaled breath, would enable a better characterization of the kind and extent of tobacco exposure. This review aims to perform a critical analysis of the up-to-date literature focused on the simultaneous determination of multiple tobacco smoke biomarkers studied in different biological matrices, due to the exposure to secondhand smoke (SHS) and thirdhand smoke (THS). Target biomarkers included both tobacco-specific biomarkers-nicotine and tobacco specific nitrosamine biomarkers-and tobacco-related biomarkers, such as those from polycyclic aromatic hydrocarbons, volatile organic compounds, metals and carbon monoxide. To conclude, we discuss the suitability of determining multiple biomarkers through several relevant examples of SHS and THS exposure.

Assessment of the exposure to harmful and potentially harmful constituents in healthy Japanese smokers using a novel tobacco vapor product compared with conventional cigarettes and smoking abstinence

The objectives of this clinical study were to demonstrate a reduction in exposure to selected harmful and potentially harmful constituents (HPHCs), and to assess product use behavior, in Japanese healthy adult smokers who switched to a novel tobacco vapor product (NTV). 60 smokers were randomly assigned for 5 days to either (a) a group who switched to an NTV (n = 20), (b) a group who continued to smoke their own brand of conventional cigarettes (CC, n = 20) or (c) a smoking abstinence group (SA, n = 20). Fifteen biomarkers of exposure (BoEs) to 14 HPHCs and pyrene were measured at baseline, day 3 and 5. Product use behavior was assessed by measuring product consumption, nicotine uptake and puffing topography. During investigations, increases were observed in product consumption and total puff volume in NTV group subjects as compared to baseline. Additionally, nicotine uptake in the NTV group was approximately half that observed in the CC group. BoE values were significantly reduced in the NTV group as compared to those in the CC group. Significantly, the magnitude of the reduction in exposure to HPHCs observed in the NTV group (49-94%) was close to that observed for the SA group (39-95%).

Smoking Exposure in Early Pregnancy and Adverse Pregnancy Outcomes: Usefulness of Urinary Tobacco-Specific Nitrosamine Metabolite 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanol Levels

OBJECTIVES

The aim was to investigate the effect of -maternal smoking exposure assessed by urinary tobacco-specific nitrosamine metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-a1-butanol (NNAL) with adverse pregnancy outcomes.

METHODS

A total of 251 pregnant women were recruited. Urinary cotinine and NNAL were measured. Participants' sociodemographics were obtained by questionnaire and pregnancy outcomes were collected by charts review after delivery.

RESULTS

The prevalence of smoking was 8.4% (21 of 249), 1.2% (3 of 241), and 3.7% (9 of 241) in pregnant women according to questionnaire, cotinine, and NNAL, respectively. As compared with questionnaire positivity and cotinine levels, women with positive NNAL were independent determinants for spontaneous abortion (adjusted OR 12.357, 95% CI 2.053-74.368), preterm birth (adjusted OR 22.239, 95% CI 3.737-132.357), and small for gestational age (adjusted OR 6.915, 95% CI 1.385-34.524).

CONCLUSIONS

Urinary NNAL might be a useful biomarker in detection of maternal smoking status in association with adverse pregnancy outcomes. Use of this marker in preconception and pregnancy counselling before planning pregnancy may allow prevention of several adverse pregnancy outcomes.

Adolescent Exposure to Toxic Volatile Organic Chemicals From E-Cigarettes

BACKGROUND

There is an urgent need to understand the safety of e-cigarettes with adolescents. We sought to identify the presence of chemical toxicants associated with e-cigarette use among adolescents.

METHODS

Adolescent e-cigarette users (≥1 use within the past 30 days, ≥10 lifetime e-cigarette use episodes) were divided into e-cigarette-only users (no cigarettes in the past 30 days, urine 4-[methylnitrosamino]-1-[3-pyridyl]-1-butanol [NNAL] level <1 pg/mL of creatinine; n = 67), dual users (use of cigarettes in the past 30 days in addition to e-cigarettes, NNAL level >30 pg/mL; n = 16), and never-using controls (N = 20). Saliva was collected within 24 hours of the last e-cigarette use for analysis of cotinine and urine for analysis of NNAL and levels of 8 volatile organic chemical compounds. Bivariate analyses compared e-cigarette-only users with dual users, and regression analyses compared e-cigarette-only users with dual users and controls on levels of toxicants.

RESULTS

The participants were 16.4 years old on average. Urine excretion of metabolites of benzene, ethylene oxide, acrylonitrile, acrolein, and acrylamide was significantly higher in dual users versus e-cigarette-only users (all P < .05). Excretion of metabolites of acrylonitrile, acrolein, propylene oxide, acrylamide, and crotonaldehyde were significantly higher in e-cigarette-only users compared with controls (all P < .05).

CONCLUSIONS

Although e-cigarette vapor may be less hazardous than tobacco smoke, our findings can be used to challenge the idea that e-cigarette vapor is safe, because many of the volatile organic compounds we identified are carcinogenic. Messaging to teenagers should include warnings about the potential risk from toxic exposure to carcinogenic compounds generated by these products.

Assessing modified risk tobacco and nicotine products: Description of the scientific framework and assessment of a closed modular electronic cigarette

Cigarette smoking causes many human diseases including cardiovascular disease, lung disease and cancer. Novel tobacco products with reduced yields of toxicants compared to cigarettes, such as tobacco-heating products, snus and electronic cigarettes, hold great potential for reducing the harms associated with tobacco use. In the UK several public health agencies have advocated a potential role for novel products in tobacco harm reduction. Public Health England has stated that "The current best estimate is that e-cigarettes are around 95% less harmful than smoking" and the Royal College of Physicians has urged public health to "Promote e-cigarettes widely as substitute for smoking". Health related claims on novel products such as 'reduced exposure' and 'reduced risk' should be substantiated using a weight of evidence approach based on a comprehensive scientific assessment. The US FDA, has provided draft guidance outlining a framework to assess novel products as Modified Risk Tobacco Products (MRTP). Based on this, we now propose a framework comprising pre-clinical, clinical, and population studies to assess the risk profile of novel tobacco products. Additionally, the utility of this framework is assessed through the pre-clinical and part of the clinical comparison of a commercial e-cigarette (Vype ePen) with a scientific reference cigarette (3R4F) and the results of these studies suggest that ePen has the potential to be a reduced risk product.

Prevalence, Duration and Severity of Parkinson's Disease in Germany: A Combined Meta-Analysis from Literature Data and Outpatient Samples

BACKGROUND

Epidemiological data on the prevalence of Parkinson's disease (PD) in Germany are limited. The aims of this study were to estimate the age- and gender-specific prevalence of PD in Germany as well as the severity and illness duration.

SUMMARY

A systematic literature search was performed in 5 different databases. European studies were included if they reported age- and gender-specific numbers of prevalence rates of PD. Meta-analytic approaches were applied to derive age- and gender-specific pooled prevalence estimates. Data of 4 German outpatient samples were incorporated to calculate the proportion of patients with PD in Germany grouped by Hoehn and Yahr (HY) stages and disease duration. In the German population, 178,169 cases of PD were estimated (prevalence: 217.22/100,000). The estimated relative illness duration was 40% with less than 5 years, 31% with 5-9 years, and 29% with more than 9 years. The proportions for different HY stages were estimated at 13% (I), 30% (II), 35% (III), 17% (IV), and 4% (V), respectively. Key Message: We provide an up-to-date estimation of age- and gender-specific as well as severity-based prevalence figures for PD in Germany. Further community studies are needed to estimate population-based severity distributions and distributions of non-motor symptoms in PD.

Nicotine, Carcinogen, and Toxin Exposure in Long-Term E-Cigarette and Nicotine Replacement Therapy Users: A Cross-sectional Study

BACKGROUND

Given the rapid increase in the popularity of e-cigarettes and the paucity of associated longitudinal health-related data, the need to assess the potential risks of long-term use is essential.

OBJECTIVE

To compare exposure to nicotine, tobacco-related carcinogens, and toxins among smokers of combustible cigarettes only, former smokers with long-term e-cigarette use only, former smokers with long-term nicotine replacement therapy (NRT) use only, long-term dual users of both combustible cigarettes and e-cigarettes, and long-term users of both combustible cigarettes and NRT.

DESIGN

Cross-sectional study.

SETTING

United Kingdom.

PARTICIPANTS

The following 5 groups were purposively recruited: combustible cigarette-only users, former smokers with long-term (≥6 months) e-cigarette-only or NRT-only use, and long-term dual combustible cigarette-e-cigarette or combustible cigarette-NRT users (n = 36 to 37 per group; total n = 181).

MEASUREMENTS

Sociodemographic and smoking characteristics were assessed. Participants provided urine and saliva samples and were analyzed for biomarkers of nicotine, tobacco-specific N-nitrosamines (TSNAs), and volatile organic compounds (VOCs).

RESULTS

After confounders were controlled for, no clear between-group differences in salivary or urinary biomarkers of nicotine intake were found. The e-cigarette-only and NRT-only users had significantly lower metabolite levels for TSNAs (including the carcinogenic metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol [NNAL]) and VOCs (including metabolites of the toxins acrolein; acrylamide; acrylonitrile; 1,3-butadiene; and ethylene oxide) than combustible cigarette-only, dual combustible cigarette-e-cigarette, or dual combustible cigarette-NRT users. The e-cigarette-only users had significantly lower NNAL levels than all other groups. Combustible cigarette-only, dual combustible cigarette-NRT, and dual combustible cigarette-e-cigarette users had largely similar levels of TSNA and VOC metabolites.

LIMITATION

Cross-sectional design with self-selected sample.

CONCLUSION

Former smokers with long-term e-cigarette-only or NRT-only use may obtain roughly similar levels of nicotine compared with smokers of combustible cigarettes only, but results varied. Long-term NRT-only and e-cigarette-only use, but not dual use of NRTs or e-cigarettes with combustible cigarettes, is associated with substantially reduced levels of measured carcinogens and toxins relative to smoking only combustible cigarettes.

PRIMARY FUNDING SOURCE

Cancer Research UK.

Fit-for-purpose biomarker immunoassay qualification and validation: three case studies

AIM

To improve on the efficiency of biomarker assay readiness, and for reliable biomarker data to support three drug programs, we implemented a fit-for-purpose approach, qualifying two biomarker assays and validating a third. Results/methodology: The qualification strategy and selection of experiments for two exploratory biomarkers (CXCL1, CCL19) was determined by the intended use of the biomarker data. The third biomarker, IL-6, was validated as the data would be used in monitoring patient safety during dose-escalation studies in a Phase I trial. All three assays passed a priori acceptance criteria.

CONCLUSION

These assays highlight strategies and methodologies for a fit-for-purpose approach. Minimum qualification, full qualification and validation were chosen and supported programs at different stages of drug development.

Reductions in biomarkers of exposure, impacts on smoking urge and assessment of product use and tolerability in adult smokers following partial or complete substitution of cigarettes with electronic cigarettes

Background

Electronic cigarettes (e-cigarettes) are popular alternatives to conventional cigarettes among adult smokers wishing to reduce their exposure to harmful smoke constituents. However, little information exists on the relative internal exposures resulting from the exclusive or dual use of e-cigarettes.

Methods

Measurements of product use; adverse events; changes in smoking urge; and blood, urine and exhaled breath biomarkers of exposure (BoE) representing toxicants believed to contribute to smoking related diseases were made at baseline and after five days of product use in 105 clinically-confined smokers randomized into groups that partially or completely substituted their usual brand combustible cigarette with commercial e-cigarettes, or discontinued all nicotine and tobacco products.

Results

Subjects switching to e-cigarettes had significantly lower levels (29 %–95 %) of urinary BoEs after 5 days. Nicotine equivalents declined by 25 %–40 %. Dual users who substituted half of their self-reported daily cigarette consumption with e-cigarettes experienced 7 %–38 % reductions, but had increases (1 %–20 %) in nicotine equivalents. Blood nicotine biomarker levels were lower in the cessation (75 %–96 %) and e-cigarette use groups (11 %–83 %); dual users had no significant reductions. All groups experienced significant decreases in exhaled CO (27 %–89 %). Exhaled NO increases (46 %–63 %) were observed in the cessation and e-cigarette use groups; dual users had minimal changes. By Day 5, all groups had greater reductions in smoking urge compared to cessation. However, reductions were larger in the dual use group. No serious adverse events were observed.

Conclusions

Exposures to harmful smoke toxicants were observed to be lower in smokers who completely or partially replaced their cigarettes with e-cigarettes over five days.

Reductions in biomarkers of exposure (BoE) to harmful or potentially harmful constituents (HPHCs) following partial or complete substitution of cigarettes with electronic cigarettes in adult smokers

Changes in fifteen urine, blood and exhaled breath BoEs of HPHCs representing classes of compounds reported by FDA to be significant contributors to smoking-associated disease risks were measured in 105 clinical-confined subjects following randomization and a five-day forced-switch from usual brand conventional combustible cigarettes to: (i) exclusive commercial e-cigarette use; (ii) dual-use of commercial e-cigarettes and the subject's usual cigarette brand; or (iii) discontinued use of all tobacco or nicotine products. Levels of urinary biomarkers in subjects that completely substituted their usual cigarette with e-cigarettes were significantly lower (29-95%) after 5 days. Percent reductions in eight of nine urinary BoEs were indistinguishable to smokers who had quit smoking, except for nicotine equivalents, which declined by 25-40%. Dual users who halved self-reported daily cigarette consumption with e-cigarettes exhibited reductions (7-38%) in eight of nine urinary biomarkers, but had increase (1-20%) in nicotine equivalents. Reductions were broadly proportional to the reduced numbers of cigarettes smoked. Dual user urinary nicotine equivalents were slightly higher, but not statistically significant. After 5 days, blood nicotine biomarker levels were lower in the cessation (75-96%) and exclusive use groups (11-83%); with dual users experiencing no significant reductions. All subjects experienced significant decreases in exhaled CO. Decreases in the cessation and exclusive groups ranged from 88-89% and 27-32% in dual users. Exhaled NO increased in the cessation and exclusive groups (46-63% respectively), whereas the dual users experienced minimal changes. Overall, smokers who completely or partially substituted conventional cigarettes with e-cigarettes over five days, experienced reductions in HPHCs.

A cross-sectional study of biomarkers of exposure and effect in smokers and moist snuff consumers

Cigarette smoking is a major risk factor for several chronic diseases. Epidemiological data indicate the use of smokeless tobacco (ST) is associated with significantly lower risk for smoking-related diseases compared to cigarettes. Several biomarkers of exposure (BioExp) and effect (BioEff) associated with smoking and use of moist snuff (ST) were evaluated.

A single site, cross-sectional clinical study enrolled three groups of generally healthy male smokers (SMK), moist snuff consumers (MSC), and non-tobacco consumers (NTC), and several BioExp and BioEff were evaluated.

Blood and urinary BioExp, including total nicotine equivalents and tobacco-specific nitrosamines, were higher in MSC compared to SMK. Biomarkers of combustion-related toxicants and cadmium were elevated in SMK. Elevated levels of some BioEff associated with oxidative stress (urinary isoprostanes and leukotriene E4), inflammation (white blood cell count), platelet activation (thromboxane metabolites), and lipid metabolism (apolipoprotein B100 and oxidized low-density lipoprotein) were observed in SMK relative to NTC and MSC (all p<0.05). The non-smoking groups (MSC and NTC) showed similar levels of combustion-related BioExp and BioEff.

Higher levels of exposure to nicotine and some N′-nitrosamines may be observed in MSC, and SMK are exposed to higher levels of combustion-related toxicants. Changes in BioEff consistent with some aspects of inflammation, oxidative stress, and altered lipid metabolism were detected in SMK compared to the non-smoking groups. The biomarker data further improve our understanding of pathophysiological changes and the risk continuum associated with various tobacco products, and could be useful components of future assessments of tobacco products.

Application of CE-MS to a metabonomics study of human urine from cigarette smokers and non-smokers

BACKGROUND

Novel biomarkers of exposure and early adverse effects are needed for comparative studies of combustible and non-combustible tobacco products for regulatory authority evaluation. Metabolic biomarkers reflect both gene and environmental effects.

RESULTS

CE-MS has been applied to human urine samples from non-smokers and smokers of cigarettes at two tar levels. Validated chemometric models were able to separate smokers from non-smokers, with discrimination mainly based on the presence of nicotine metabolites. With these removed, it still proved possible to discriminate smokers from non-smokers with models now based on endogenous metabolites. The biochemical relevance of these biomarkers is discussed.

CONCLUSION

This proof-of-principle metabonomics study illustrates the potential of CE-MS to discover novel biomarkers in urine from tobacco users.

Study of cardiovascular disease biomarkers among tobacco consumers, part 1: biomarkers of exposure

A study was conducted to evaluate biomarkers of biological effect and physiological assessments related to cardiovascular disease (CVD) among adult male cigarette smokers (SMK), moist snuff consumers (MSC) and non-consumers of tobacco (NTC). Additionally, biomarkers of tobacco and tobacco smoke exposure (BoE) were measured in spot urines and are reported here. Except for the BoE to nicotine and NNK, BoE were generally greater in SMK compared with MSC, and BoE were generally not different in comparisons of MSC and NTC. Results demonstrated that MSC had lower systemic exposures to many harmful and potentially harmful constituents than SMK, which is consistent with epidemiological data that indicate a differential in CVD risk between these groups.

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.

Biomarkers of tobacco smoke exposure

Diseases and death caused by exposure to tobacco smoke have become the single most serious preventable public health concern. Thus, biomarkers that can monitor tobacco exposure and health effects can play a critical role in tobacco product regulation and public health policy. Biomarkers of exposure to tobacco toxicants are well established and have been used in population studies to establish public policy regarding exposure to second-hand smoke, an example being the nicotine metabolite cotinine, which can be measured in urine. Biomarkers of biological response to tobacco smoking range from those indicative of inflammation to mRNA and microRNA patterns related to tobacco use and/or disease state. Biomarkers identifying individuals with an increased risk for a pathological response to tobacco have also been described. The challenge for any novel technology or biomarker is its translation to clinical and/or regulatory application, a process that requires first technical validation of the assay and then careful consideration of the context the biomarker assay may be used in the regulatory setting. Nonetheless, the current efforts to investigate new biomarker of tobacco smoke exposure promise to offer powerful new tools in addressing the health hazards of tobacco product use. This review will examine such biomarkers, albeit with a focus on those related to cigarette smoking.