Tobacco-Specific Nitrosamines (NNAL, NNN, NAT, and NAB) Exposures in the US Population Assessment of Tobacco and Health (PATH) Study Wave 1 (2013-2014)

Nicotiana alkaloids-intervened phospholipid ozonolysis at the air-water interface

Cigarette nicotiana alkaloids associated with lung and cardiovascular diseases attack enormous attention. However, the mechanism at the molecular level between nicotiana alkaloids and phospholipid ozonolysis remains elusive. Herein, we investigated the interfacial ozonolysis of a hung droplet containing 1-palmitoyl-2-oleoyl-sn-phosphatidylglycerol (POPG) intervened by nicotiana alkaloids (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, NNK; rac-N'-nitrosonornicotine, NNN; nicotine; and (R,S)-N-nitrosoanasabine, NAT) and followed by on-line mass spectrometry analysis. NNK and NNN showed an acceleration on the interfacial ozonolysis, while nicotine and NAT inhibited this chemistry. Such acceleration/inhibition on POPG ozonolysis was positively correlated with nicotiana alkaloid concentrations. The reaction rate constants suggested that the ozonolysis of lung phospholipids exposed to cigarette smoke at the air-water interface occurred rapidly. A possible mechanism of the hydrophilic/oleophilic nature of nicotiana alkaloids mediating the packing density of POPG was proposed. NNK and NNN with a hydrophilic nature inserted into the POPG monolayer loosed the packing, but nicotine and NAT with an oleophilic nature let the POPG closely pack and shield the CC double bonds exposed to ozone (O3). These results gain the knowledge of nicotiana alkaloids mediated phospholipid ozonolysis at the molecule level and provide a method for online interfacial reaction studies associated with elevated indoor pollutants on public health.

Assessment of toxicological validity using tobacco emission condensates: A comparative analysis of emissions and condensates from 3R4F reference cigarettes and heated tobacco products

The tobacco emission condensate, henceforth referred to as "tobacco condensate," plays a critical role in assessing the toxicity of tobacco products. This condensate, derived from tobacco emissions, provides an optimized liquid concentrate for storage and concentration control. Thus, the validation of its constituents is vital for toxicity assessments. This study used tobacco condensates from 3R4F cigarettes and three heated tobacco product (HTP) variants to quantify and contrast organic compounds (OCs) therein. The hazard index (HI) for tobacco emissions and condensates was determined to ascertain the assessment validity. The total particulate matter (TPM) for 3R4F registered at 17,667 μg cig-1, with its total OC (TOC) at 3777 μg cig-1. HTPs' TPM and TOC were 9342 ± 1918 μg cig-1 and 5258 ± 593 μg stick-1, respectively. 3R4F's heightened TPM likely arises from tar, while HTPs' OC concentrations are influenced by vegetable glycerin (2236-2688 μg stick-1) and propylene glycol (589-610 μg stick-1). During the condensation process, a substantial proportion of OCs in 3R4F smoke underwent significant concentration decreases, in contrast to HTPs, where fewer than half of the examined OCs exhibited notable concentration declines. The HI for tobacco emissions exhibited a marginally higher value compared to tobacco condensate, with variations ranging from 7.92% (HTPs) to 18.6% (3R4F), denoting a minimal differential. These observations emphasize the importance of accurate OC recovery techniques to maintain the validity and reliability of toxicity assessments based on tobacco condensates. This study not only deepens the comprehension of chemical behaviors in tobacco products but also establishes a novel benchmark for their toxicity evaluation, with profound implications for public health strategies and consumer protection.

Exposure to Tobacco-Specific Nitrosamines Among People Who Vape, Smoke, or do Neither: A Systematic Review and Meta-Analysis

INTRODUCTION

Smoking exposes people to high levels of Tobacco-Specific Nitrosamines (TSNAs), which include potent carcinogens. We systematically reviewed TSNA exposure between people smoking, vaping, and doing neither.

AIMS AND METHODS

Databases were searched between August 2017-March 2022, using vaping-related terms. Peer-reviewed articles reporting TSNA metabolites (NNAL, NNN, NAB, and NAT) levels in bio-samples among adults exclusively vaping, exclusively smoking, or doing neither were included. Where possible, meta-analyses were conducted.

RESULTS

Of 12 781 identified studies, 22 were included. TSNA levels fell substantially when people who smoke switched to vaping in longitudinal studies and were lower among people who vaped compared to smoked in cross-sectional studies. Levels of TSNAs were similar when comparing people who switched from smoking to vaping, to those who switched to no use of nicotine products, in longitudinal studies. Levels were higher among people who vaped compared to people who neither vaped nor smoked in cross-sectional studies.When comparing people who vaped to smoked: pooled urinary NNAL was 79% lower across three randomized controlled trials and 96% lower across three cross-sectional studies; pooled NAB was 87% lower and NAT 94% lower in two cross-sectional studies. When comparing people who neither vaped nor smoked to people who vaped, pooled urinary NNAL was 80%, NAB 26%, and NAT 27% lower in two cross-sectional studies. Other longitudinal data, and NNN levels could not be pooled.

CONCLUSIONS

Exposure to all TSNAs was lower among people who vaped compared to people who smoked. Levels were higher among people who vaped compared to people who neither vaped nor smoked.

IMPLICATIONS

As well as TSNAs, there are many other toxicant exposures from smoking and vaping that can increase the risk of disease. However, it is likely that the reduced exposure to TSNAs from vaping relative to smoking reduces the risk to health of those who use vaping products to quit smoking. Future high-quality research, with robust definitions of exclusive vaping and smoking, and accounting for TSNAs half-lives, is needed to fully assess exposure to TSNAs among people who vape.

CYP2A6 Activity and Cigarette Consumption Interact in Smoking-Related Lung Cancer Susceptibility

Cigarette smoke, containing both nicotine and carcinogens, causes lung cancer. However, not all smokers develop lung cancer, highlighting the importance of the interaction between host susceptibility and environmental exposure in tumorigenesis. Here, we aimed to delineate the interaction between metabolizing ability of tobacco carcinogens and smoking intensity in mediating genetic susceptibility to smoking-related lung tumorigenesis. Single-variant and gene-based associations of 43 tobacco carcinogen-metabolizing genes with lung cancer were analyzed using summary statistics and individual-level genetic data, followed by causal inference of Mendelian randomization, mediation analysis, and structural equation modeling. Cigarette smoke-exposed cell models were used to detect gene expression patterns in relation to specific alleles. Data from the International Lung Cancer Consortium (29,266 cases and 56,450 controls) and UK Biobank (2,155 cases and 376,329 controls) indicated that the genetic variant rs56113850 C>T located in intron 4 of CYP2A6 was significantly associated with decreased lung cancer risk among smokers (OR = 0.88, 95% confidence interval = 0.85-0.91, P = 2.18 × 10-16), which might interact (Pinteraction = 0.028) with and partially be mediated (ORindirect = 0.987) by smoking status. Smoking intensity accounted for 82.3% of the effect of CYP2A6 activity on lung cancer risk but entirely mediated the genetic effect of rs56113850. Mechanistically, the rs56113850 T allele rescued the downregulation of CYP2A6 caused by cigarette smoke exposure, potentially through preferential recruitment of transcription factor helicase-like transcription factor. Together, this study provides additional insights into the interplay between host susceptibility and carcinogen exposure in smoking-related lung tumorigenesis.

SIGNIFICANCE

The causal pathway connecting CYP2A6 genetic variability and activity, cigarette consumption, and lung cancer susceptibility in smokers highlights the need for behavior modification interventions based on host susceptibility for cancer prevention.

From cultivation to cancer: formation of N-nitrosamines and other carcinogens in smokeless tobacco and their mutagenic implications

Tobacco use is a major cause of preventable morbidity and mortality globally. Tobacco products, including smokeless tobacco (ST), generally contain tobacco-specific N-nitrosamines (TSNAs), such as N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-butanone (NNK), which are potent carcinogens that cause mutations in critical genes in human DNA. This review covers the series of biochemical and chemical transformations, related to TSNAs, leading from tobacco cultivation to cancer initiation. A key aim of this review is to provide a greater understanding of TSNAs: their precursors, the microbial and chemical mechanisms that contribute to their formation in ST, their mutagenicity leading to cancer due to ST use, and potential means of lowering TSNA levels in tobacco products. TSNAs are not present in harvested tobacco but can form due to nitrosating agents reacting with tobacco alkaloids present in tobacco during certain types of curing. TSNAs can also form during or following ST production when certain microorganisms perform nitrate metabolism, with dissimilatory nitrate reductases converting nitrate to nitrite that is then released into tobacco and reacts chemically with tobacco alkaloids. When ST usage occurs, TSNAs are absorbed and metabolized to reactive compounds that form DNA adducts leading to mutations in critical target genes, including the RAS oncogenes and the p53 tumor suppressor gene. DNA repair mechanisms remove most adducts induced by carcinogens, thus preventing many but not all mutations. Lastly, because TSNAs and other agents cause cancer, previously documented strategies for lowering their levels in ST products are discussed, including using tobacco with lower nornicotine levels, pasteurization and other means of eliminating microorganisms, omitting fermentation and fire-curing, refrigerating ST products, and including nitrite scavenging chemicals as ST ingredients.

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.

Biomarkers of Electronic Nicotine Delivery Systems (ENDS) Use

This perspective summarizes available evidence on biomarkers of exposure in electronic nicotine delivery system (ENDS) users to aid the overall assessment of the health consequences of using ENDS. Identification of novel biomarkers of exposure specific to ENDS use remains challenging because chemicals emitted from ENDS devices have many familiar sources. The biomarker levels of many tobacco-related toxicants measured in biological samples collected from ENDS users did not differ significantly from non-users, except for nicotine metabolites and a small number of biomarkers of exposure to volatile organic compounds and tobacco-specific tobacco nitrosamines. Several studies have shown that while exposed to nicotine, long-term exclusive ENDS users showed significantly lower levels of toxicant biomarkers than cigarette smokers. Studies have also shown that concurrent users of ENDS and combustible cigarettes ('dual users') are not reducing overall exposure to harmful toxicants compared to exclusive cigarette smokers. Because of an absence of validated ENDS-specific biomarkers, we recommend combining several biomarkers to differentiate tobacco product user groups in population-based studies and monitor ENDS compliance in randomized controlled trials. Using a panel of biomarkers would provide a better understanding of health effects related to ENDS use.

Hand nicotine as an independent marker of thirdhand smoke pollution in children's environments

BACKGROUND

Hand nicotine (HN) levels measure children's exposure to tobacco smoke pollutants from thirdhand and secondhand smoke. HN is associated with urinary and salivary cotinine, but the associations of HN with other tobacco smoke exposure (TSE) markers remain unknown.

OBJECTIVES

We compared levels of HN and four urinary TSE biomarkers: cotinine, trans-3'-hydroxycotinine (3HC), nicotelline N-oxides, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and children's sociodemographic and TSE patterns. We also examined if HN is a plausible pathway for children's exposure to active smoking.

METHODS

Data were collected from 175 non-smoking patients (Mean (SD) age = 5.4 (3.4) years) who lived with ≥1 cigarette smoker(s). HN and TSE biomarker levels were determined using LC-MS/MS. Multivariate and multivariable regression analyses were conducted to examine associations between TSE markers and parent-reported measures, controlling for sociodemographics.

RESULTS

Of the five markers of TSE, cotinine (R² = 0.221; p = 0.003) and HN (R² = 0.247; p = 0.001) showed the strongest overall associations. Of the five markers, only cotinine showed significantly higher levels among Black children (β^=0.307,p<0.05) independent of age, reported exposure, and home smoking bans. Cotinine (β^=0.010,p<0.05), NNAL (β^=0.012,p<0.05), and HN (β^=0.011,p<0.05) showed significant positive associations with reported exposure independent of race, age, and home smoking bans. NNAL (β^=-0.285,p<0.05) and HN (β^=-0.336,p<0.05), but not cotinine, 3HC, and N-oxides, showed significantly lower levels among children who lived in homes with smoking bans. Child age, hand surface area, home smoking ban, and reported exposure independently accounted for 21 % of the variance in HN levels (p = 0.002). HN accounted for 30 % of the variance in cotinine independent of child race and child age.

DISCUSSION

HN levels were associated with modifiable tobacco-related behaviors and shows promise as a marker of sources of THS pollution in a child's environment not captured by measurement of urinary cotinine alone. HN levels provide additional information about TSE, complementing other biomarkers when assessing children's overall TSE.

Optimum Urine Cotinine and NNAL Levels to Distinguish Smokers from Non-Smokers by the Changes in Tobacco Control Policy in Korea from 2008 to 2018

INTRODUCTION

We examined the age- and sex-specific distributions of biomarkers of tobacco smoke exposure to determine the optimal cutoffs to distinguish smokers from non-smokers over the last 10 years in Korea, during which smoking prevalence and secondhand smoke (SHS) exposure declined due to changes in tobacco control policy.

METHODS

We analyzed data from the Korea National Health and Nutrition Examination Survey on creatinine-adjusted urinary cotinine (2008-2018; 33 429 adults: 15 653 males and 17 776 females) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL; 2016-2018; 6337 adults: 3091 males and 3246 females). We determined the optimal cutoffs and confidence intervals (CIs) to distinguish smokers from non-smokers using receiver operator characteristic curve analysis and bootstrapping (1000 resamples).

RESULTS

The optimal cutoff values of creatinine-adjusted urine cotinine and NNAL concentration were 20.9 ng/mg (95% CI: 20.8-21.0, sensitivity: 96.6%, specificity: 93.8%) and 8.9 pg/mg (95% CI: 8.8-8.9, sensitivity: 94.0%, specificity: 94.7%), respectively, in 2016-2018. The optimal cutoffs of both biomarkers increased with age and were higher in females than in males for NNAL concentration. In both sexes, the optimal cutoff of urine cotinine continuously declined over the study period.

CONCLUSIONS

The optimal cotinine cutoff declined along with smoking prevalence and levels of SHS exposure due to enforcement of tobacco control policies, including smoke-free ordinances and tax increases. Monitoring of biomarkers of tobacco exposure appears necessary for verification of smoking status and regulatory use.

IMPLICATIONS

Our results based on nationally representative data suggest that a large decrease in the optimal cutoff value of urine cotinine to distinguish smokers from non-smokers was caused by decreases in smoking prevalence and SHS exposure following enforcement of tobacco control policies over the last 10 years. We determined the optimal cutoff values of urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), which were not previously reported in representative population in Asia, to enable more accurate estimation of exposure to tobacco smoke and proper assessment of disease risks. Gender- and age-specific differences in the optimal cutoffs require further study. Monitoring of biomarkers of tobacco smoke exposure seems necessary for verification of smoking status and regulatory use.

Einfluss des Rauchens auf den Gastrointestinaltrakt

Hintergrund

Nikotin ist ein hochwirksames Suchtgift, das bei regelmäßiger Einnahme chronische oder unheilbare Erkrankungen und somit eine eingeschränkte Lebensqualität zur Folge haben kann.

Fragestellung

Das Ziel dieser Übersichtsarbeit besteht darin, mögliche gesundheitliche Folgen des Rauchens auf den Gastrointestinaltrakt aufzuzeigen und einen Überblick über raucherassoziierte neoplastische und nichtneoplastische gastrointestinale Erkrankungen zu geben.

Material und Methode

Anhand einer ausführlichen Literaturrecherche wird der aktuelle Wissensstand zu raucherassoziierten Folgen auf den Gastrointestinaltrakt dargestellt.

Ergebnisse

Rauchen ist ein wesentlicher Risikofaktor für die Entstehung neoplastischer und nichtneoplastischer Erkrankungen des gesamten Gastrointestinaltrakts. Diese weisen in der radiologischen Bildgebung allerdings keine spezifischen, raucherassoziierten Merkmale auf.

Schlussfolgerung

Die Kenntnis einer Raucheranamnese sowie möglicher Auswirkungen von Nikotin auf den Gastrointestinaltrakt können in der radiologischen Bildinterpretation hilfreich sein sowie die diagnostische Entscheidungsfähigkeit und Genauigkeit verbessern.

High Levels of the Carcinogenic Tobacco-Specific Nitrosamine NNAL and Associated Findings in Children of Smokers: A Case Series

High levels of NNAL, the tobacco smoke exposure (TSE) biomarker of the carcinogen 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), indicate future cancer risk. A prior study of smokers’ children revealed NNAL levels as high as active smokers. Therefore, we conducted a case series to examine the sociodemographics, TSE and clinical patterns, and other TSE biomarker levels in 9 children with extreme NNAL levels of >200 pg/ml to generate hypotheses and explore potential causes and implications. We identified 0 to 4-year-olds who presented to an emergency setting and lived with ⩾1 smoker who were part of a parental tobacco cessation trial (n = 461). Of these children, 52 had urinary NNAL, cotinine, and N-oxides results (n = 52). Nine children (17.3%) had NNAL levels >200 pg/ml, ranging from 206.4 to 1399.0 pg/ml (Median (Mdn) = 489.2 pg/ml; Interquartile Range (IQR) = 222.7-1289.3 pg/ml). The cotinine Mdn (IQR) was 38.5 (10.3-102.2) ng/ml and the N-oxides Mdn (IQR) = 93.8 (24.7-109.6) pg/ml. While all biomarker levels were alarmingly high, these young children would not have been flagged for very high cancer risk based on urinary cotinine levels alone. This underscores the critical role of comprehensive TSE biomarker measurement in capturing different TSE exposure patterns and assessing children’s future risk for cancer and other TSE-related morbidities.

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 the salivary cotinine cut-offs to discriminate smokers and non-smokers before and after Spanish smoke-free legislation

INTRODUCTION

High levels of cotinine in non-smokers indicate passive exposure to tobacco smoke. This study aims to evaluate variations in salivary cotinine cut-offs to discriminate smokers and non-smokers before and after the implementation of smoke-free legislation (Law 28/2005 and Law 42/2010) in a sample of the adult population of Barcelona, Spain.

METHODS

This longitudinal study analyzes salivary cotinine samples and self-reported information from a representative sample (n = 676) of the adult population from Barcelona before and after the approval of smoke-free legislation. We calculated the receiver operating characteristic (ROC) curves, to obtain optimal cotinine cut-off points to discriminate between smokers and non-smokers overall, by sex and age, and their corresponding sensitivity, specificity, and area under the curve. We used linear mixed-effects models, with individuals as random effects, to model the percentage change of cotinine concentration before and after the implementation of both laws.

RESULTS

The mean salivary cotinine concentration was significantly lower post-2010 law (-85.8%, p < 0.001). The ROC curves determined that the optimal cotinine cut-off points for discriminating non-smokers and smokers were 10.8 ng/mL (pre-2005 law) and 5.6 ng/mL (post-2010 law), with a post-2010 law sensitivity of 92.6%, specificity of 98.4%, and an area under the curve of 97.0%. The post-2010 law cotinine cut-off points were 5.6 ng/mL for males and 1.9 ng/mL for females.

CONCLUSION

The implementation of Spanish smoke-free legislation was effective in reducing secondhand smoke exposure and, therefore, also in reducing the cut-off point for salivary cotinine concentration. This value should be used to better assess tobacco smoke exposure in this population.

Exposure in the tobacco fields: Genetic damage and oxidative stress in tobacco farmers occupationally exposed during harvest and grading seasons

Agricultural workers engaged in tobacco cultivation are constantly exposed to large amounts of harmful agents, such as pesticides and nicotine. Furthermore, most of the flue-cured tobacco leaves are manually graded exposing workers to agents such as tobacco-specific nitrosamines. This study aimed to evaluate genetic damage and oxidative stress in tobacco farmers occupationally exposed during the harvest and grading seasons. We obtained data on DNA damage detected in Comet assay in blood cells and micronucleus experiment with buccal cells from 241 individuals. The serum cotinine levels and nitrates were also evaluated. The Comet Assay results showed a showed an increased visual score for males and females during harvest time and tobacco grading. An increase of micronucleated and binucleated cells was observed in the grading group compared to the control and harvest groups. The oxidative stress measurements showed a clear increase of thiobarbituric acid reactive substances (TBARS) in tobacco farmers during harvest time, and trolox equivalent antioxidant capacity (TEAC) in individuals during harvest and grading time compared to the controls. Significant increases of the cotinine levels were observed during the harvest and grading period (harvest>grading), and nitrates for the grading period compared to the control. In this study, tobacco farmers presented compromised DNA integrity associated with enhanced oxidative stress levels.

Metabolism and DNA Adduct Formation of Tobacco-Specific N-Nitrosamines

The tobacco-specific N-nitrosamines 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) always occur together and exclusively in tobacco products or in environments contaminated by tobacco smoke. They have been classified as "carcinogenic to humans" by the International Agency for Research on Cancer. In 1998, we published a review of the biochemistry, biology and carcinogenicity of tobacco-specific nitrosamines. Over the past 20 years, considerable progress has been made in our understanding of the mechanisms of metabolism and DNA adduct formation by these two important carcinogens, along with progress on their carcinogenicity and mutagenicity. In this review, we aim to provide an update on the carcinogenicity and mechanisms of the metabolism and DNA interactions of NNK and NNN.

Secondhand smoke exposure in school children in Malta assessed through urinary biomarkers

School children may be exposed to secondhand smoke (SHS) either at home, in transit or in social gatherings permitting smoking in their presence. Questionnaires about SHS often underestimate prevalence and extent of exposure. A more accurate tool is the use of biomarkers such as cotinine (COT) and trans-3'-hydrocycotinine (3HC) as biomarkers of SHS exposure, alongside 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a reduction product in the body of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), both potent carcinogens. We measured urinary COT, 3HC and total NNAL using sensitive and specific high-performance LC-MS/MS methods. The limit of quantification (LOQ) for each assay were 0.05 ng/mL, 0.1 ng/mL and 0.25 pg/mL respectively. The aim of this study was to evaluate the exposure to SHS of school children (9-11 years), from five public schools in the island of Malta, from questionnaire information about smoking at home and verify it by urinary biomarker data of COT, 3HC and NNAL. These biomarkers were measurable in 99.4%, 95.4% and 98.3% of the participating children respectively. From the children reporting smoking at home, 11% had a history of asthma and had COT, 3HC and NNAL geometric mean concentrations double compared to the non-asthmatic group. In has been confirmed that non-smokers exposed to SHS and THS have a higher NNAL/COT ratio than the group identified as smokers according to specific and defined COT threshold levels (despite the fact that a priori, the entire study group was composed of non-smokers). The implication of high measured levels of urinary NNAL in children should be of concern given its potency. A main effects multifactor ANOVA model was developed and the children's house and school locations and the smoking frequency were statistically significant to predict the levels of the three metabolites. For 3HC only, the status of the employment of the mother was also an important predictor.

Smokeless tobacco and cigarette smoking: chemical mechanisms and cancer prevention

Tobacco products present a deadly combination of nicotine addiction and carcinogen exposure resulting in millions of cancer deaths per year worldwide. A plethora of smokeless tobacco products lead to unacceptable exposure to multiple carcinogens, including the tobacco-specific nitrosamine N'-nitrosonornicotine, a likely cause of the commonly occurring oral cavity cancers observed particularly in South-East Asian countries. Cigarettes continue to deliver a large number of carcinogens, including tobacco-specific nitrosamines, polycyclic aromatic hydrocarbons and volatile organic compounds. The multiple carcinogens in cigarette smoke are responsible for the complex mutations observed in critical cancer genes. The exposure of smokeless tobacco users and smokers to carcinogens and toxicants can now be monitored by urinary and DNA adduct biomarkers that may be able to identify those individuals at highest risk of cancer so that effective cancer prevention interventions can be initiated. Regulation of the levels of carcinogens, toxicants and nicotine in tobacco products and evidence-based tobacco control efforts are now recognized as established pathways to preventing tobacco related cancer.

Exposure to Toxicants Associated With Use and Transitions Between Cigarettes, e-Cigarettes, and No Tobacco

IMPORTANCE

Transitions between e-cigarettes and cigarettes are common among tobacco users, but empirical evidence on the health outcomes of switching tobacco products is scarce.

OBJECTIVES

To examine changes in urinary biomarkers between baseline and 1-year follow-up among adult tobacco users switching between e-cigarettes and cigarettes.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from wave 1 (baseline, September 2013 to December 2014) and wave 2 (1-year follow-up, October 2014 to October 2015) of the Population Assessment of Tobacco and Health Study. A subset of the probability sample of US adults who voluntarily provided biospecimens at 2 waves was analyzed. Participants were divided into 3 mutually exclusive groups at baseline: exclusive cigarette smokers, exclusive e-cigarette users, and dual users. Data analysis was performed in 2021.

EXPOSURES

Harmful and potentially harmful constituents included nicotine metabolites, tobacco-specific nitrosamines (TSNAs; including 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol [NNAL]), metals, polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs).

MAIN OUTCOMES AND MEASURES

Within-participant changes in 55 urinary biomarkers of exposure (BOEs) to harmful and potentially harmful constituents were examined using multivariable regression models.

RESULTS

Among 3211 participants (55.6% women, 68.3% White, 13.2% Black, and 11.8% Hispanic) at baseline, 21.9% of exclusive cigarette users, 42.8% of exclusive e-cigarette users, and 62.1% of dual users changed product use at follow-up (all percentages are weighted). There was a significant reduction in urine concentrations of TSNAs, PAHs, and VOCs when users transitioned from exclusive cigarette to exclusive e-cigarette use, with a 92% decrease in NNAL, from a mean of 168.4 pg/mg creatinine (95% CI, 102.3-277.1 pg/mg creatinine) to 12.9 pg/mg creatinine (95% CI, 6.4-25.7 pg/mg creatinine; P < .001). A similar panel of BOEs decreased when dual users transitioned to exclusive e-cigarette use; NNAL levels decreased by 96%, from a mean of 143.4 pg/mg creatinine (95% CI, 86.7-237.0 pg/mg creatinine) to 6.3 pg/mg creatinine (95% CI, 3.5-11.4 pg/mg creatinine; P < .001). Nicotine metabolites, TSNAs, PAHs, and VOCs significantly increased when baseline exclusive e-cigarette users transitioned to exclusive cigarette use or dual use. Switching from exclusive cigarette use to dual use was not associated with significant decreases in BOEs.

CONCLUSIONS AND RELEVANCE

This national cohort study provides evidence on the potential harm reduction associated with transitioning from exclusive cigarette use or dual use to exclusive e-cigarette use. e-Cigarettes tend to supplement cigarettes through dual use instead of cessation at the population level. Continuous monitoring of BOE at the population level and assessment of BOE change by product transition are warranted, as well as defined adverse health outcomes.

Comparison of Levels of Three Tobacco Smoke Exposure Biomarkers in Children of Smokers

Objectives: Cotinine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and N-oxides are biomarkers of tobacco smoke exposure (TSE) used to assess short- and longer-term TSE. The objective of this study was to assess the associations between these TSE biomarkers, sociodemographics, parental smoking, and child TSE patterns among 0–17-year-olds. Methods: A convenience sample of 179 pediatric patients (mean (SD) age = 7.9 (4.3) years) who lived with ≥1 smoker and who had parental assessments completed and urine samples analyzed for the three TSE biomarkers of interest were included. Biomarker levels were log-transformed, univariate regression models were built and Pearson correlations were assessed. Results: In total, 100% of children had detectable levels of cotinine and >96% had detectable NNAL and N-oxide levels. The geometric means of cotinine, NNAL, and N-oxide levels were 10.1 ng/mL, 25.3 pg/mL, and 22.9 pg/mL, respectively. The mean (SD) number of daily cigarettes smoked by parents was 10.6 (6.0) cigarettes. Child age negatively correlated with urinary cotinine (r = −0.202, p = 0.007) and log NNAL levels (r = −0.275, p < 0.001). The highest log-cotinine levels were in children who were younger, of African American race, and whose parents had a lower education, an annual income ≤USD15,000, and no smoking bans. The highest log-NNAL and N-oxide levels were in children whose parents had a lower education, had no smoking bans, and were around higher numbers of cigarettes. Conclusion: Children of smokers who were younger, African American, and had no smoking bans had the highest TSE biomarker levels. Targeted interventions are needed to reduce TSE levels among high-risk children.

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).

1,2-Propylene Glycol: A Biomarker of Exposure Specific to e-Cigarette Consumption

Over the past decade, new emerging tobacco and nicotine-delivery products have changed the tobacco landscape. Especially, electronic cigarettes (ECs) have been suggested to be considered for tobacco harm reduction, reinforcing the need to identify novel biomarkers of exposure (BoE) specific to the EC use as this would complement exposure assessment and product compliance monitoring. Therefore, a sensitive LC-MS/MS method for the quantification of 1,2-propylene glycol (PG) and glycerol (G), the main e-liquid constituents, was established. PG and G were analyzed in plasma and urine samples from a clinical study comparing five nicotine product user groups, users of combustible cigarettes (CC), electronic cigarettes (EC), heated tobacco products (HTP), oral tobacco (OT), and oral/dermal nicotine delivery products (used for nicotine replacement therapy, NRT) with a control group of non-users (NU). Data demonstrate significantly elevated PG levels in urine and plasma in EC users compared to users of CC, HTP, NRT, OT as well as NU. In addition, PG in plasma and urine of vapers significantly correlated with nicotine (plasma) and total nicotine equivalents (urine), biomarkers reflecting product consumption, emphasizing the high specificity of PG as a BoE for EC consumption. We therefore suggest the use of PG as BoE in urine and/or plasma in order to monitor EC use compliance in exposure assessments.

A Low-Cost, High-Throughput Digital Image Analysis of Stain Patterns on Smoked Cigarette Filter Butts to Estimate Mainstream Smoke Exposure

Standard machine smoking protocols provide useful information for examining the impact of design parameters, such as filter ventilation, on mainstream smoke delivery. Unfortunately, their results do not accurately reflect human smoke exposure. Clinical research and topography devices in human studies yield insights into how products are used, but a clinical setting or smoking a cigarette attached to such a device may alter smoking behavior. To better understand smokers' use of filtered cigarette products in a more natural environment, we developed a low-cost, high-throughput approach to estimate mainstream cigarette smoke exposure on a per-cigarette basis. This approach uses an inexpensive flatbed scanner to scan smoked cigarette filter butts and custom software to analyze tar-staining patterns. Total luminosity, or optical staining density, of the scanned images provides quantitative information proportional to mainstream smoke-constituent deliveries on a cigarette-by-cigarette basis. Duplicate sample analysis using this new approach and our laboratory's gold-standard liquid chromatography/tandem mass spectrometry (LC/MS/MS) solanesol method yielded comparable results (+7% bias) from the analysis of 20 commercial cigarettes brands (menthol and nonmentholated). The brands varied in design parameters such as length, filter ventilation, and diameter. Plots correlating the luminosity to mainstream smoked-nicotine deliveries on a per-cigarette basis for these cigarette brands were linear (average R2 > 0.91 for nicotine and R2 > 0.83 for the tobacco-specific nitrosamine NNK), on a per-brand basis, with linearity ranging from 0.15 to 3.00 mg nicotine/cigarette. Analysis of spent cigarette filters allows exposures to be characterized on a per-cigarette basis or a "daily dose" via summing across results from all filter butts collected over a 24 h period. This scanner method has a 100-fold lower initial capital cost for equipment than the LC/MS/MS solanesol method and provides high-throughput results (~200 samples per day). Thus, this new method is useful for characterizing exposure related to filtered tobacco-product use.

Sexual identity differences in biomarkers of tobacco exposure among women in a national sample

BACKGROUND

Sexual minority women are consistently at increased risk for tobacco use compared to heterosexual women. Neither biomarkers of nicotine exposure nor biomarkers of tobacco toxicant exposure have been examined by sexual identity.

METHODS

This study used interview and biomarker data from women in the biomarker core sample of Wave 1 of the Population Assessment of Tobacco and Health (PATH) study (2013-2014; n = 4930). We examined associations of sexual identity with nicotine exposure (measured with urinary cotinine and TNE-2) and with tobacco-specific nitrosamines (measured with urinary NNAL). Multivariable regression modeling was used to examine these associations among the full biomarker core sample, among past 30-day tobacco users, and among exclusive established cigarette users before and after controlling for tobacco use quantity and intensity.

RESULTS

In the full biomarker sample of women, prior to adjusting for tobacco use quantity and intensity, bisexual women had significantly higher cotinine, TNE-2, and NNAL levels compared to heterosexual women. Among exclusive established cigarette users, gay/lesbian women had significantly higher NNAL compared to heterosexual women prior to adjusting for tobacco quantity and intensity. No differences by sexual identity were found after adjusting for tobacco use quantity and intensity.

CONCLUSIONS

This is the first study to demonstrate differences in biological markers of tobacco exposure by sexual identity among women in the U.S. This has important public health implications as greater exposure to both nicotine and to tobacco-specific nitrosamines are strongly linked to cancer risk.

Estimating the Impact of Tobacco Parity and Harm Reduction Tax Proposals Using the Experimental Tobacco Marketplace

Taxes are a demonstrably effective method to suppress tobacco use. This study examined the effects of the tobacco parity (i.e., imposing taxes equally on all tobacco products) and the harm reduction (i.e., applying taxes in proportion to the products' levels of harm) tax proposals on demand and substitution across products. A crowdsourced sample of cigarette smokers (n = 35) completed purchasing trials with increasing tax magnitudes across different tax tiers in the Experimental Tobacco Marketplace in a repeated-measures design. Products were placed in three tax tiers (high, medium, and no tax) according to each proposal's goal. The results indicated that total nicotine (mg) purchased was not significantly different between the proposals, with higher taxes yielding lower demand. However, as taxes increased, the tobacco parity proposal decreased the purchasing of all tobacco products and increased the purchasing of medicinal nicotine (i.e., the no tax tier). Conversely, the harm reduction proposal resulted in greater purchases of electronic nicotine delivery systems and smokeless tobacco (i.e., the medium tax tier). These findings support tobacco taxation as a robust tool for suppressing purchasing and suggest that differential taxation in proportion to product risk would be an effective way to incentivize smokers to switch from smoked to unsmoked products. Further studies should investigate the unintended consequences of their implementation.

Associations between Biomarkers of Exposure and Lung Cancer Risk among Exclusive Cigarette Smokers in the Golestan Cohort Study

Biomarkers of tobacco exposure are known to be associated with disease risk but previous studies are limited in number and restricted to certain regions. We conducted a nested case-control study examining baseline levels and subsequent lung cancer incidence among current male exclusive cigarette smokers in the Golestan Cohort Study in Iran. We calculated geometric mean biomarker concentrations for 28 matched cases and 52 controls for the correlation of biomarker levels among controls and for adjusted odds' ratios (ORs) for lung cancer incidence by biomarker concentration, accounting for demographic characteristics, smoking quantity and duration, and opium use. Lung cancer cases had higher average levels of most biomarkers including total nicotine equivalents (TNE-2), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and 3-hydroxyfluorene (3-FLU). Many biomarkers correlated highly with one another including TNE-2 with NNAL and N-Acetyl-S-(2-cyanoethyl)-L-cysteine (2CYEMA), and N-Acetyl-S-(4-hydroxy-2-buten-1-yl)-L-cysteine (t4HBEMA) with N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine (3HMPMA) and N-Acetyl-S-(4-hydroxy-2-methyl-2-buten-1-yl)-L-cysteine (4HMBEMA). Lung cancer risk increased with concentration for several biomarkers, including TNE-2 (OR = 2.22, 95% CI = 1.03, 4.78) and NNN (OR = 2.44, 95% CI = 1.13, 5.27), and estimates were significant after further adjustment for demographic and smoking characteristics for 2CYEMA (OR = 2.17, 95% CI = 1.03, 4.55), N-Acetyl-S-(2-carbamoylethyl)-L-cysteine (2CAEMA) (OR = 2.14, 95% CI = 1.01, 4.55), and N-Acetyl-S-(2-hydroxypropyl)-L-cysteine (2HPMA) (OR = 2.85, 95% CI = 1.04, 7.81). Estimates were not significant with adjustment for opium use. Concentrations of many biomarkers were higher at the baseline for participants who subsequently developed lung cancer than among the matched controls. Odds of lung cancer were higher for several biomarkers including with adjustment for smoking exposure for some but not with adjustment for opium use.