Urinary Cotinine and Cotinine + Trans-3'-Hydroxycotinine (TNE-2) Cut-points for Distinguishing Tobacco Use from Nonuse in the United States: PATH Study (2013-2014)

Validating Wave 1 (2014) Urinary Cotinine and TNE-2 Cut-points for Differentiating Wave 4 (2017) Cigarette Use from Non-use in the United States Using Data from the PATH Study

BACKGROUND

Sex and racial/ethnic identity-specific cut-points for validating tobacco use using Wave 1 (W1) of the Population Assessment of Tobacco and Health (PATH) Study were published in 2020. The current study establishes predictive validity of the W1 (2014) urinary cotinine and total nicotine equivalents-2 (TNE-2) cut-points on estimating Wave 4 (W4; 2017) tobacco use.

METHODS

For exclusive and polytobacco cigarette use, weighted prevalence estimates based on W4 self-report alone and with exceeding the W1 cut-point were calculated to identify the percentage missed without biochemical verification. Sensitivity and specificity of W1 cut-points on W4 self-reported tobacco use status were examined. ROC curves were used to determine the optimal W4 cut-points to distinguish past 30-day users from non-users, and evaluate whether the cut-points significantly differed from W1.

RESULTS

Agreement between W4 self-reported use and exceeding the W1 cut-points was high overall and when stratified by demographic subgroups (0.7%-4.4% of use was missed if relying on self-report alone). The predictive validity of using the W1 cut-points to classify exclusive cigarette and polytobacco cigarette use at W4 was high (>90% sensitivity and specificity, except among polytobacco Hispanic smokers). Cut-points derived using W4 data did not significantly differ from the W1-derived cut-points [e.g., W1 exclusive = 40.5 ng/mL cotinine (95% confidence interval, CI: 26.1-62.8), W4 exclusive = 29.9 ng/mL cotinine (95% CI: 13.5-66.4)], among most demographic subgroups.

CONCLUSIONS

The W1 cut-points remain valid for biochemical verification of self-reported tobacco use in W4.

IMPACT

Findings from can be used in clinical and epidemiologic studies to reduce misclassification of cigarette smoking status.

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.

Variability in Urinary Nicotine Exposure Biomarker Levels Between Waves 1 (2013-2014) and 2 (2014-2015) in the Population Assessment of Tobacco and Health Study

INTRODUCTION

To date, no studies have evaluated the consistency of biomarker levels in people who smoke over a long-time period in real-world conditions with a large number of subjects and included use behavior and measures of nicotine metabolism. We evaluated the variability of biomarkers of nicotine exposure over approximately a 1-year period in people who exclusively smoke cigarettes, including intensity and recency of use and brand switching to assess impact on understanding associations with product characteristics.

AIMS AND METHODS

Multivariate regression analysis of longitudinal repeated measures of urinary biomarkers of nicotine exposure from 916 adults in the Population Assessment of Tobacco and Health (PATH) Study with demographic characteristics and use behavior variables. Intraclass correlation coefficients (ICCs) were calculated to examine individual variation of nicotine biomarkers and the uncertainty of repeat measures at two time points (Waves 1 and 2).

RESULTS

Age, race, and urinary creatinine were significant covariates of urinary cotinine. When including use behavior, recency, and intensity of use were highly significant and variance decreased to a higher extent between than within subjects. The ICC for urinary cotinine decreased from 0.7530 with no use behavior variables in the model to 0.5763 when included. Similar results were found for total nicotine equivalents.

CONCLUSIONS

Urinary nicotine biomarkers in the PATH Study showed good consistency between Waves 1 and 2. Use behavior measures such as time since last smoked a cigarette and number of cigarettes smoked in the past 30 days are important to include when assessing factors that may influence biomarker concentrations.

IMPLICATIONS

The results of this study show that the consistency of the nicotine biomarkers cotinine and total nicotine equivalents in spot urine samples from Waves 1 to 2 of the PATH Study is high enough that these data are useful to evaluate the association of cigarette characteristics with biomarkers of exposure under real-world use conditions.

Furan Metabolites Are Elevated in Users of Various Tobacco Products and Cannabis

Humans are exposed to furan, a toxicant and possible human carcinogen, through multiple sources including diet and tobacco smoke. The urinary metabolites of furan are derived from the reaction of its toxic metabolite with protein nucleophiles and are biomarkers of exposure and potential harm. An established isotopic dilution liquid-chromatography mass spectrometry method was used to measure these biomarkers in urine from users of e-cigarettes, cannabis, and/or combustible tobacco with/without reduced nicotine levels. Amounts of furan mercapturic acid metabolites were higher in these individuals relative to nonsmokers, indicating that they may be at risk for potential furan-derived toxicities.

Blood DNA methylation signatures of lifestyle exposures: tobacco and alcohol consumption

BACKGROUND

Smoking and alcohol consumption may compromise health by way of epigenetic modifications. Epigenetic signatures of alcohol and tobacco consumption could provide insights into the reversibility of phenotypic changes incurred with differing levels of lifestyle exposures. This study describes and validates two novel epigenetic signatures of tobacco (EpiTob) and alcohol (EpiAlc) consumption and investigates their association with disease outcomes.

METHODS

The epigenetic signatures, EpiTob and EpiAlc, were developed using data from the Swiss Kidney Project on Genes in Hypertension (SKIPOGH) (N = 689). Epigenetic and phenotypic data available from the 1921 (N = 550) and 1936 (N = 1091) Lothian Birth Cohort (LBC) studies, and two publicly available datasets on GEO Accession (GSE50660, N = 464; and GSE110043, N = 94) were used to validate the signatures. A multivariable logistic regression model, adjusting for age and sex, was used to assess the association between self-reported tobacco or alcohol consumption and the respective epigenetic signature, as well as to estimate the association between CVD and epigenetic signatures. A Cox proportional hazard model was used to estimate the risk of mortality in association with the EpiTob and EpiAlc signatures.

RESULTS

The EpiTob signature was positively associated with self-reported tobacco consumption for current or never smokers with explained variance ranging from 0.49 (LBC1921) to 0.72 (LBC1936) (pseudo-R2). In the SKIPOGH, LBC1921 and LBC1936 cohorts, the epigenetic signature for alcohol consumption explained limited variance in association with self-reported alcohol status [i.e., non-drinker, moderate drinker, and heavy drinker] (pseudo-R2 = 0.05, 0.03 and 0.03, respectively), although this improved considerably when measuring self-reported alcohol consumption with standardized units consumed per week (SKIPOGH R2 = 0.21; LBC1921 R2 = 0.31; LBC1936 R2 = 0.41). Both signatures were associated with history of CVD in SKIPOGH and LBC1936, but not in LBC1921. The EpiTob signature was associated with increased risk of all-cause and lung-cancer specific mortality in the 1936 and 1921 LBC cohorts.

CONCLUSIONS

This study found the EpiTob and EpiAlc signatures to be well-correlated with self-reported exposure status and associated with long-term health outcomes. Epigenetic signatures of lifestyle exposures may reduce measurement issues and biases and could aid in risk stratification for informing early-stage targeted interventions.

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.

Anabasine and Anatabine Exposure Attributable to Cigarette Smoking: National Health and Nutrition Examination Survey (NHANES) 2013-2014

Anabasine and anatabine are minor alkaloids in tobacco products and are precursors for tobacco-specific nitrosamines (TSNAs). The levels of these two compounds have been used to differentiate tobacco product sources, monitor compliance with smoking cessation programs, and for biomonitoring in TSNA-related studies. The concentrations of urinary anabasine and anatabine were measured in a representative sample of U.S. adults who smoked cigarettes (N = 770) during the 2013−2014 National Health and Nutrition Examination Survey (NHANES) study cycle, which was the first cycle where urinary anabasine and anatabine data became available. Weighted geometric means (GM) and geometric least squares means (LSM) with 95% confidence intervals were calculated for urinary anabasine and anatabine categorized by tobacco-use status [cigarettes per day (CPD) and smoking frequency] and demographic characteristics. Smoking ≥20 CPD was associated with 3.6× higher anabasine GM and 4.8× higher anatabine GM compared with smoking <10 CPD. Compared with non-daily smoking, daily smoking was associated with higher GMs for urinary anabasine (1.41 ng/mL vs. 6.28 ng/mL) and anatabine (1.62 ng/mL vs. 9.24 ng/mL). Urinary anabasine and anatabine concentrations exceeded the 2 ng/mL cut point in 86% and 91% of urine samples from people who smoke (PWS) daily, respectively; in comparison, 100% of them had serum cotinine concentrations greater than the established 10 ng/mL cut point. We compared these minor tobacco alkaloid levels to those of serum cotinine to assess their suitability as indicators of recent tobacco use at established cut points and found that their optimal cut point values would be lower than the established values. This is the first time that anabasine and anatabine are reported for urine collected from a U.S. population-representative sample of NHANES study participants, providing a snapshot of exposure levels for adults who smoked during 2013−2014. The results of this study serve as an initial reference point for future analysis of NHANES cycles, where changes in the national level of urinary anabasine and anatabine can be monitored among people who smoke to show the effect of changes in tobacco policy.

Simultaneous quantification of urinary tobacco and marijuana metabolites using solid-supported liquid-liquid extraction coupled with liquid chromatography tandem mass spectrometry

Co-exposure to tobacco and marijuana has become common in areas where recreational marijuana use is legal. To assist in the determination of the combined health risks of this co-exposure, an analytical method capable of simultaneously measuring tobacco and marijuana metabolites is needed to reduce laboratory costs and the required sample volume. So far, no such analytical method exists. Thus, we developed and validated a method to simultaneously quantify urinary levels of trans-3'-hydroxycotinine (3OH-COT), cotinine (COT), and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (COOH-THC) to assess co-exposure to tobacco and marijuana. Urine (200 µL) was spiked with labelled internal standards and enzymatically hydrolyzed to liberate the conjugated analytes before extraction using solid-supported liquid-liquid extraction (SLE) with ethyl acetate serving as an eluent. The target analytes were separated on a C18 (4.6 × 100 mm, 5 μm) analytical column with a gradient mobile phase elution and analyzed using tandem mass spectrometry with multiple reaction monitoring of target ion transitions. Positive electrospray ionization (ESI) was used for 3OH-COT and COT, while negative ESI was used for COOH-THC. The total run time was 13 min. The extraction recoveries were 18.4-23.9 % (3OH-COT), 65.1-96.8 % (COT), and 80.6-95.4 % (COOH-THC). The method limits of quantification were 5.0 ng/mL (3OH-COT) and 2.5 ng/mL (COT and COOH-THC). The method showed good accuracy (82.5-98.5 %) and precision (1.22-6.21 % within-day precision and 1.42-6.26 % between-day precision). The target analytes were stable for at least 144 h inside the autosampler (10 °C). The analyses of reference materials and 146 urine samples demonstrated good method performance. The use of a 96-well plate for preparation makes the method useful for the analysis of large numbers of samples.

Loss of MMR and TGFBR2 Increases the Susceptibility to Microbiota-Dependent Inflammation-Associated Colon Cancer

BACKGROUND AND AIMS

Mutations in DNA mismatch repair (MMR) genes are causative in Lynch syndrome and a significant proportion of sporadic colorectal cancers (CRCs). MMR-deficient (dMMR) CRCs display increased mutation rates, with mutations frequently accumulating at short repetitive DNA sequences throughout the genome (microsatellite instability). The TGFBR2 gene is one of the most frequently mutated genes in dMMR CRCs. Therefore, we generated an animal model to study how the loss of both TGFBR2 signaling impacts dMMR-driven intestinal tumorigenesis in vivo and explore the impact of the gut microbiota.

METHODS

We generated VCMsh2/Tgfbr2 mice in which Msh2^loxP and Tgfbr2^loxP alleles are inactivated by Villin-Cre recombinase in the intestinal epithelium. VCMsh2/Tgfbr2 mice were analyzed for their rate of intestinal cancer development and for the mutational spectra and gene expression profiles of tumors. In addition, we assessed the impact of chemically induced chronic inflammation and gut microbiota composition on colorectal tumorigenesis.

RESULTS

VCMsh2/Tgfbr2 mice developed small intestinal adenocarcinomas and CRCs with histopathological features highly similar to CRCs in Lynch syndrome patients. The CRCs in VCMsh2/Tgfbr2 mice were associated with the presence of colitis and displayed genetic and histological features that resembled inflammation-associated CRCs in human patients. The development of CRCs in VCMsh2/Tgfbr2 mice was strongly modulated by the gut microbiota composition, which in turn was impacted by the TGFBR2 status of the tumors.

CONCLUSIONS

Our results demonstrate a synergistic interaction between MMR and TGFBR2 inactivation in inflammation-associated colon tumorigenesis and highlight the crucial impact of the gut microbiota on modulating the incidence of inflammation-associated CRCs.

Minor Tobacco Alkaloids as Biomarkers to Distinguish Combusted Tobacco Use From Electronic Nicotine Delivery Systems Use. Two New Analytical Methods

Biomarkers for the use of electronic nicotine delivery systems (ENDS) are desirable for studies of the health effects of electronic cigarettes and related devices. However, the aerosols inhaled from these devices do not contain substances that are unique to this class of products, i.e., substances that are not present in cigarette smoke or those that do not have common environmental or dietary sources. Consequently, identifying selective biomarkers for ENDS use remains a challenge. If co-use of conventional tobacco products can be definitively ruled out, then nicotine and its metabolites are suitable for assessing exposure. Self-reports from questionnaires are often used to obtain information on product use. But self-reports may not always be accurate, and are not amenable to obtaining quantitative information on exposure. An alternative approach is to use selective biomarkers for conventional tobacco products to definitively rule out their use. In this article, we describe two new LC-MS/MS methods for the minor tobacco alkaloids anabasine, anatabine, nicotelline, anatalline, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a tobacco-specific nitrosamine metabolite, all biomarkers that are selective for the use of conventional tobacco products. Applications of these biomarkers in studies of ENDS use and dual use of ENDS and conventional tobacco products are also discussed.

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.

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.