Respiratory retention of nicotine and urinary excretion of nicotine and its five major metabolites in adult male smokers

Nicotine Intake in Adult Pod E-cigarette Users: Impact of User and Device Characteristics

INTRODUCTION

This study examined user behavior, e-cigarette dependence, and device characteristics on nicotine intake among users of pod-mod e-cigarettes.

AIMS AND METHODS

In 2019-2020, people who use pod-mods in the San Francisco Bay Area completed questionnaires and provided a urine sample for analysis of total nicotine equivalents (TNE). The relationship between TNE and e-cigarette use, e-cigarette brands, e-liquid nicotine strength, e-cigarette dependence, and urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), as a measure of combustible cigarette exposure, were examined.

RESULTS

Of 100 participants (64% male, 71% in the 18-34 age group, 45% white), 53 used JUUL primarily, 12 used Puff Bar primarily, and 35 used other brands, including Suorin; 48 participants reported current cigarette smoking. Participants most often reported use of e-liquid with 4.5%-6.0% nicotine (68%), fruit (35%), tobacco (28%), and menthol or mint flavors (26%), used e-cigarettes on 25.5 (SD = 6.3) days a month, 10.2 (SD = 14.2) times a day, and 40% used 1-2 pods/cartridges per week. In bivariate analysis, urinary TNE was higher with greater frequency (days used) and intensity (number of pods used) of e-cigarette use, e-cigarette dependence, and combustible cigarette use. In multivariable analysis, days of e-cigarette use in the last 30 days, number of pods used per week, and NNAL levels were significantly associated with TNE. There was no significant impact of e-liquid nicotine strength on TNE.

CONCLUSIONS

Nicotine intake among people who used pod-mod e-cigarettes increased with e-cigarette consumption and e-cigarette dependence, but not with e-liquid nicotine strength. Our findings may inform whether FDA adopts a nicotine standard for e-cigarettes.

IMPLICATIONS

The study examined how device and user characteristics influence nicotine intake among pod-mod e-cigarette users. Nicotine intake increased with frequency (days of e-cigarette use in past 30 days) intensity of use (number of pods used per day) and e-cigarette dependence but not with the flavor or nicotine concentration of the e-liquids. Regulation of nicotine concentration of e-liquids is unlikely to influence nicotine exposure among adult experienced pod-mod users.

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.

A Mixed-Methods Study on Use of Different Tobacco Products among Younger and Older Adults with Lower and Higher Levels of Nicotine Exposure in California in 2019-2020

An increasing number of tobacco products are entering the market, offering a variety of options to attain desired nicotine intake. However, little is known about the effect of this diverse marketplace on the experiences and nicotine exposure among tobacco users. A mixed-methods study examined experiences with tobacco products among individuals with relatively lower or higher levels of biomarkers of nicotine exposure. Semi-structured interviews were conducted with younger and older adults to examine tobacco use behaviors, addiction to tobacco products, and nicotine effects. Younger and older adults provided similar narratives about addiction and nicotine effects, which were similar across age groups, product types (i.e., ENDS, combustible cigarettes, or oral tobacco products), and having lower or higher nicotine exposure. Some individuals with higher nicotine exposure who switched from combustible cigarettes to another product (e.g., ENDS) found similar or greater access and perceived addiction to nicotine. Adults with higher and lower levels of nicotine exposure provided narratives consistent with features of nicotine addiction, regardless of age and products used. Availability of multiple tobacco products may be associated with greater access and exposure to nicotine. Addiction may occur at low levels of use and with non-cigarette products.

Urinary Nicotine Metabolites and Self-Reported Tobacco Use Among Adults in the Population Assessment of Tobacco and Health (PATH) Study, 2013-2014

INTRODUCTION

The Population Assessment of Tobacco and Health (PATH) Study is a longitudinal cohort study on tobacco use behavior, attitudes and beliefs, and tobacco-related health outcomes, including biomarkers of tobacco exposure in the U.S. population. In this report we provide a summary of urinary nicotine metabolite measurements among adult users and non-users of tobacco from Wave 1 (2013-2014) of the PATH Study.

METHODS

Total nicotine and its metabolites including cotinine, trans-3'-hydroxycotinine (HCTT), and other minor metabolites were measured in more than 11 500 adult participants by liquid chromatography tandem mass spectrometry methods. Weighted geometric means (GM) and least square means from statistical modeling were calculated for non-users and users of various tobacco products.

RESULTS

Among daily users, the highest GM concentrations of nicotine, cotinine and HCTT were found in exclusive smokeless tobacco users, and the lowest in exclusive e-cigarette users. Exclusive combustible product users had intermediate concentrations, similar to those found in users of multiple products (polyusers). Concentrations increased with age within the categories of tobacco users, and differences associated with gender, race/ethnicity and educational attainment were also noted among user categories. Recent (past 12 months) former users had GM cotinine concentrations that were more than threefold greater than never users.

CONCLUSIONS

These urinary nicotine metabolite data provide quantification of nicotine exposure representative of the entire US adult population during 2013-2014 and may serve as a reference for similar analyses in future measurements within this study.

IMPLICATIONS

Nicotine and its metabolites in urine provide perhaps the most fundamental biomarkers of recent nicotine exposure. This report, based on Wave 1 of the Population Assessment of Tobacco and Health (PATH) Study, provides the first nationally representative data describing urinary nicotine biomarker concentrations in both non-users, and users of a variety of tobacco products including combustible, e-cigarette and smokeless products. These data provide a urinary biomarker concentration snapshot in time for the entire US population during 2013-2014, and will provide a basis for comparison with future results from continuing, periodic evaluations in the PATH Study.

Fast analysis of selected compounds in inhaled and exhaled vapor phase of cigarette smoke to evaluate components retained in the upper respiratory tract

RATIONALE

The aim of this work is to use a new design of online sampling photoionization mass spectrometer to analyze chemical ingredients in inhaled and exhaled cigarette smoke directly without separation.

METHODS

Based on vacuum ultraviolet photoionization time-of-flight mass spectrometry (VUV-PI-TOFMS) and a sampling system, a newly developed rapid online sampling design approach was used for the upper respiratory tract retention study of gaseous mainstream cigarette smoke components during smoking. The cigarette smoke inhaled or exhaled by seven subjects who displayed three different smoking patterns was directly sampled into a vacuum chamber, photoionized, and analyzed using TOFMS.

RESULTS

Fourteen species, comprising aldehydes, ketones, phenol, methanethiol, nitrogen-containing heterocyclic compounds and unsaturated hydrocarbons, were identified in the cigarette smoke obtained from Virginia-type cigarettes. The upper respiratory tract results for these compounds were similar for smokers with the three different smoking patterns: aldehyde and ketone constituents had a high retention level of more than 60%; phenol, methanethiol, and nitrogen-containing heterocyclic compounds were retained at between 30% and 70%; and the retention of unsaturated hydrocarbons was about 20%-60%. The retention trend of the same smoke components in Virginia-type cigarettes by subjects from the three smoking patterns (A, B, and C) was consistent, and the retentions all increased with increased smoking age (A < B < C).

CONCLUSIONS

This is the first report of a new online sampling design approach to the study of cigarette smoke components in inhaled and exhaled breath, to evaluate components retained in the upper respiratory tract by subjects with different smoking patterns. This method has good repeatability, and the results indicated that this is a very promising tool for the study of the retention of cigarette smoke constituents.

Biochemical Verification of Tobacco Use and Abstinence: 2019 Update

BACKGROUND

The changing prevalence and patterns of tobacco use, the advent of novel nicotine delivery devices, and the development of new biomarkers prompted an update of the 2002 Society for Research on Nicotine and Tobacco (SRNT) report on whether and how to apply biomarker verification for tobacco use and abstinence.

METHODS

The SRNT Treatment Research Network convened a group of investigators with expertise in tobacco biomarkers to update the recommendations of the 2002 SNRT Biochemical Verification Report.

RESULTS

Biochemical verification of tobacco use and abstinence increases scientific rigor and is recommended in clinical trials of smoking cessation, when feasible. Sources, appropriate biospecimens, cutpoints, time of detection windows and analytic methods for carbon monoxide, cotinine (including over the counter tests), total nicotine equivalents, minor tobacco alkaloids, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol are reviewed, as well as biochemical approaches to distinguishing cigarette smoking from use of electronic nicotine delivery devices (ENDS).

CONCLUSIONS

Recommendations are provided for whether and how to use biochemical verification of tobacco use and abstinence. Guidelines are provided on which biomarkers to use, which biospecimens to use, optimal cutpoints, time windows to detection, and methodology for biochemical verifications. Use of combinations of biomarkers is recommended for assessment of ENDS use.

IMPLICATIONS

Biochemical verification increases scientific rigor, but there are drawbacks that need to be assessed to determine whether the benefits of biochemical verification outweigh the costs, including the cost of the assays, the feasibility of sample collection, the ability to draw clear conclusions based on the duration of abstinence, and the variability of the assay within the study population. This paper provides updated recommendations from the 2002 SRNT report on whether and how to use biochemical markers in determining tobacco use and abstinence.

Black Light Smokers: How Nicotine Intake and Carcinogen Exposure Differ Across Various Biobehavioral Factors

OBJECTIVE

The study objective was to identify biobehavioral variables associated with greater intake of nicotine and a tobacco carcinogen among Black light smokers who smoke 1 to 10 cigarettes per day (CPD).

METHODS

We analyzed baseline data collected from 426 Black light smokers enrolled in Kick It at Swope III (KIS III), a smoking cessation trial for Black smokers. We examined differences in concentrations of tobacco biomarkers, including urinary total nicotine equivalents (TNE) and total 4-(methylnitrosamino)-1-(3)pyridyl-1-butanonol (NNAL; a human carcinogen), across gender, age, plasma nicotine metabolite ratio (NMR), CPD, and measures of tobacco dependence, including time to first cigarette (TFC), using ANOVA.

RESULTS

Tobacco biomarker levels were significantly higher among those who smoked more CPD (6-10 vs 1-5 CPD) and those with greater reported physical dependence on tobacco. Concurrently, those who smoked 1-5 CPD smoked each cigarette more intensely than those who smoked 6-10 CPD. While we found no gender differences overall, among those who smoked 1-5 CPD, women had higher NNAL levels compared to men. The rate of nicotine metabolism, measured by the nicotine metabolite ratio, was not significantly related to TNE or NNAL levels.

CONCLUSION

Among Black Light smokers, higher cigarette consumption and greater physical dependence-but not rate of nicotine metabolism, menthol use, or socioeconomic status-were associated with greater toxicant exposure and thus a likely increased risk of tobacco-related diseases. The lack of data on light smokers, and specifically on Blacks, make this observation important given the disproportionate burden of lung cancer in this population.

A Comparison of Direct and Indirect Analytical Approaches to Measuring Total Nicotine Equivalents in Urine

Background: Total nicotine equivalents (TNE), the sum of nicotine and metabolites in urine, is a valuable tool for evaluating nicotine exposure. Most methods for measuring TNE involve two-step enzymatic hydrolysis for indirect quantification of glucuronide metabolites. Here, we describe a rapid, low-cost direct LC/MS assay.Methods: In 139 smokers' urine samples, Bland-Altman, correlation, and regression analyses were used to investigate differences in quantification of nicotine and metabolites, TNE, and nicotine metabolite ratio (NMR) between direct and indirect LC/MS methods. DNA from a subset (n = 97 smokers) was genotyped for UGT2B10*2 and UGT2B17*2, and the known impact of these variants was evaluated using urinary ratios determined by the direct versus indirect method.Results: The direct method showed high accuracy (0%-9% bias) and precision (3%-14% coefficient of variation) with similar distribution of nicotine metabolites to literary estimates and good agreement between the direct and indirect methods for nicotine, cotinine, and 3-hydroxycotinine (ratios 0.99-1.07), but less agreement for their respective glucuronides (ratios 1.16-4.17). The direct method identified urinary 3HC+3HC-GLUC/COT as having the highest concordance with plasma NMR and provided substantially better estimations of the established genetic impact of glucuronidation variants compared with the indirect method.Conclusions: Direct quantification of nicotine and metabolites is less time-consuming and less costly, and provides accurate estimates of nicotine intake, metabolism rate, and the impact of genetic variation in smokers.Impact: Lower cost and maintenance combined with high accuracy and reproducibility make the direct method ideal for smoking biomarker, NMR, and pharmacogenomics studies. Cancer Epidemiol Biomarkers Prev; 27(8); 882-91. ©2018 AACR.

Electronic cigarettes and indoor air quality: a review of studies using human volunteers

OBJECTIVE

This paper is primarily aimed to review articles on electronic cigarettes (e-cigarettes) focusing on indoor air quality (IAQ) assessment that were conducted using human volunteers under natural settings that mimic actual vaping scenarios. Such studies may give a better representation of the actual potential exposure towards e-cigarettes emissions in indoor settings.

METHODS

A systematic literature search was conducted using PubMed search engine database. Search terms such as "electronic cigarette", "e-cigarette", "electronic nicotine delivery system", and "indoor air quality" were used to identify the relevant articles to be included in this review. Articles that involved human volunteers who were asked to vape in natural settings or settings that mimic the actual vaping scenario were chosen to be reviewed. The search yielded a total of 15 published articles. Eleven articles were excluded due to 1) unavailability of its full-text (n=1), 2) did not involve human volunteers (n=5) and 3) did not involve an IAQ study (n=5). Four articles were critically reviewed in this paper.

RESULTS

From the four selected articles, two of the papers focused on the determination of nicotine level released by e-cigarettes whereas the other two covered IAQ parameters namely; particulate matters (PM), propylene glycols, formaldehyde, metals and polycyclic aromatic hydrocarbons (PAHs). Only two of the studies involved determination of biomarkers of exposure. The level of chemical contents released varied between studies. The differences in the brands of e-cigarette used, number of vapers recruited and the sensitivity of the methodologies employed in these studies may be the possible causes for such differences. However, studies using human volunteers conducted in a natural setting are more relevant to portray the actual exposure to vapors among e-cigarettes users and non-users compared to studies using a smoking machine/an exposure chamber. This is because such studies take into account the behavior of consumers and individual retention of nicotine. Such method will therefore avoid the possibility of overestimation in terms of exposures toward e-cigarettes users and non-users.

CONCLUSION

There are limited e-cigarette studies on the impact of IAQ performed using human volunteers in natural settings. The available studies however, provided inconsistent scientific evidence on the actual exposure towards the vapor contents as unstandardized methodology were used in conducting such research. Therefore, there is a need to conduct IAQ studies in natural settings by using a standardized protocol in terms of the number of vapers recruited, the size of the indoor settings, the methods used in detecting and quantifying the contents and levels of emissions and the sensitivity of the equipment used in analyzing the contents. This will help in better utilization of the findings from such studies for the use of risk assessment of the exposures towards e-cigarette emissions. There is also a need to emphasize that it is the onus of the manufacturers in providing and proving scientifically sound safety claims for their products prior to commercializing it in the market.

Biomarkers of exposure to new and emerging tobacco delivery products

Accurate and reliable measurements of exposure to tobacco products are essential for identifying and confirming patterns of tobacco product use and for assessing their potential biological effects in both human populations and experimental systems. Due to the introduction of new tobacco-derived products and the development of novel ways to modify and use conventional tobacco products, precise and specific assessments of exposure to tobacco are now more important than ever. Biomarkers that were developed and validated to measure exposure to cigarettes are being evaluated to assess their use for measuring exposure to these new products. Here, we review current methods for measuring exposure to new and emerging tobacco products, such as electronic cigarettes, little cigars, water pipes, and cigarillos. Rigorously validated biomarkers specific to these new products have not yet been identified. Here, we discuss the strengths and limitations of current approaches, including whether they provide reliable exposure estimates for new and emerging products. We provide specific guidance for choosing practical and economical biomarkers for different study designs and experimental conditions. Our goal is to help both new and experienced investigators measure exposure to tobacco products accurately and avoid common experimental errors. With the identification of the capacity gaps in biomarker research on new and emerging tobacco products, we hope to provide researchers, policymakers, and funding agencies with a clear action plan for conducting and promoting research on the patterns of use and health effects of these products.

Comprehensive review of epidemiological and animal studies on the potential carcinogenic effects of nicotine per se

The effects of long-term use of nicotine per se on cancer risk, in the absence of tobacco extract or smoke, are not clearly understood. This review evaluates the strength of published scientific evidence, in both epidemiological and animal studies, for the potential carcinogenic effects of nicotine per se; that is to act as a complete carcinogen or as a modulator of carcinogenesis. For human studies, there appears to be inadequate evidence for an association between nicotine exposure and the presence of or lack of a carcinogenic effect due to the limited information available. In animal studies, limited evidence suggests an association between long-term nicotine exposure and a lack of a complete carcinogenic effect. Conclusive studies using current bioassay guidelines, however, are missing. In studies using chemical/physical carcinogens or transgenic models, there appears to be inadequate evidence for an association between nicotine exposure and the presence of or lack of a modulating (stimulating) effect on carcinogenesis. This is primarily due to the large number of conflicting studies. In contrast, a majority of studies provides sufficient evidence for an association between nicotine exposure and enhanced carcinogenesis of cancer cells inoculated in mice. This modulating effect was especially prominent in immunocompromized mice. Overall, taking the human and animal studies into consideration, there appears to be inadequate evidence to conclude that nicotine per se does or does not cause or modulate carcinogenesis in humans. This conclusion is in agreement with the recent US Surgeon General's 2014 report on the health consequences of nicotine exposure.

Cessation of alcohol consumption decreases rate of nicotine metabolism in male alcohol-dependent smokers

BACKGROUND

Rate of nicotine metabolism is an important factor influencing cigarette smoking behavior, dependence, and efficacy of nicotine replacement therapy. The current study examined the hypothesis that chronic alcohol abuse can accelerate the rate of nicotine metabolism. Nicotine metabolite ratio (NMR, a biomarker for rate of nicotine metabolism) and patterns of nicotine metabolites were assessed at three time points after alcohol cessation.

METHODS

Participants were 22 Caucasian men randomly selected from a sample of 165 smokers entering a 7-week alcohol dependence treatment program in Poland. Data were collected at three time points: baseline (week 1, after acute alcohol detoxification), week 4, and week 7. Urine was analyzed for nicotine and metabolites and used to determine the nicotine metabolite ratio (NMR, a biomarker for rate of nicotine metabolism), and total nicotine equivalents (TNE, a biomarker for total daily nicotine exposure).

RESULTS AND CONCLUSIONS

There was a significant decrease in urine NMR over the 7 weeks after alcohol abstinence (F(2,42)=18.83, p<0.001), indicating a decrease in rate of nicotine metabolism. On average NMR decreased 50.0% from baseline to week 7 (9.6±1.3 vs 4.1±0.6). There was no change in urine TNE across the three sessions, indicating no change daily nicotine intake. The results support the idea that chronic alcohol abuse may increase the rate of nicotine metabolism, which then decreases over time after alcohol cessation. This information may help to inform future smoking cessation interventions in this population.

Different profiles of carcinogen exposure in Chinese compared with US cigarette smokers

BACKGROUND

Differences in carcinogen exposure from different cigarette products could contribute to differences in smoking-associated cancer incidence among Chinese compared with US smokers.

METHODS

Urine concentrations of metabolites of nicotine, the tobacco-specific nitrosamine (TSNA) 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and polycyclic aromatic hydrocarbon metabolites (PAHs) were compared in 238 Chinese and 203 US daily smokers.

RESULTS

Comparing Chinese versus US smokers, daily nicotine intake and nicotine intake per cigarette smoked were found to be similar. When normalised for cigarettes per day, urine NNAL excretion was fourfold higher in US smokers, while the excretion of urine metabolites of the PAHs fluorene, phenanthrene and pyrene metabolites was 50% to fourfold higher in Chinese smokers (all, p<0.0001). Similar results were seen when NNAL and PAHs excretion was normalised for daily nicotine intake.

CONCLUSIONS

Patterns of carcinogen exposure differ, with lower exposure to TSNA and higher exposure to PAHs in Chinese compared with US smokers. These results most likely reflect country differences in cigarette tobacco blends and manufacturing processes, as well as different environmental exposures.

TRIAL REGISTRATION NUMBER

NCT00264342.

UGT1A and UGT2B genetic variation alters nicotine and nitrosamine glucuronidation in european and african american smokers

BACKGROUND

Identifying sources of variation in the nicotine and nitrosamine metabolic inactivation pathways is important to understanding the relationship between smoking and cancer risk. Numerous UGT1A and UGT2B enzymes are implicated in nicotine and nitrosamine metabolism in vitro; however, little is known about their roles in vivo.

METHODS

Within UGT1A1, UGT1A4, UGT1A9, UGT2B7, UGT2B10, and UGT2B17, 47 variants were genotyped, including UGT2B10*2 and UGT2B17*2. The association between variation in these UGTs and glucuronidation activity within European and African American current smokers (n = 128), quantified as urinary ratios of the glucuronide over unconjugated compound for nicotine, cotinine, trans-3'-hydroxycotinine, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), was investigated in regression models assuming a dominant effect of variant alleles.

RESULTS

Correcting for multiple testing, three UGT2B10 variants were associated with cotinine glucuronidation, rs2331559 and rs11726322 in European Americans and rs835309 in African Americans (P ≤ 0.0002). Additional variants predominantly in UGT2B10 were nominally associated with nicotine (P = 0.008-0.04) and cotinine (P = <0.001-0.02) glucuronidation in both ethnicities in addition to UGT2B10*2 in European Americans (P = 0.01, P < 0.001). UGT2B17*2 (P = 0.03) in European Americans and UGT2B7 variants (P = 0.02-0.04) in African Americans were nominally associated with 3HC glucuronidation. UGT1A (P = 0.007-0.01), UGT2B10 (P = 0.02), and UGT2B7 (P = 0.02-0.03) variants in African Americans were nominally associated with NNAL glucuronidation.

CONCLUSIONS

Findings from this initial in vivo study support a role for multiple UGTs in the glucuronidation of tobacco-related compounds in vivo, in particular UGT2B10 and cotinine glucuronidation.

IMPACT

Findings also provide insight into ethnic differences in glucuronidation activity, which could be contributing to ethnic disparities in the risk for smoking-related cancers. Cancer Epidemiol Biomarkers Prev; 24(1); 94-104. ©2014 AACR.

Reference change values to assess changes in concentrations of biomarkers of exposure in individuals participating in a cigarette-switching study

Background: In a previous clinical study, levels of biomarkers of exposure (BoEs) for specific toxicants were significantly reduced in smokers who switched from conventional cigarettes to reduced toxicant prototype (RTP) cigarettes. Very little is known about the biological variability of tobacco smoke BoEs within individuals and sub-groups, and the descriptive group-comparison statistics might not be sufficient to understand such changes. Therefore, we assessed how different statistical methods could be used to interpret changes in urine BoE levels at the individual level.

Methods: We used non-parametric statistical reference limits, the empirical rule and reference change values (RCVs) to assess changes in levels of BoEs related to four toxicants in cigarettes smoke. Current smokers [of 6 mg and 1 mg International Organization for Standardization (ISO) tar yields] were allocated to switching to RTP groups or non-switching control groups within their respective tar bands. There were two 6 mg tar study groups, with a non-switching group (CC6, n=46) and a group switching to an RTP containing tobacco-substitute sheet and modified filter (TSS6, n=49); and three 1 mg tar smoker groups, with one non-switching (CC1, n=42), a group switching to an RTP containing tobacco-substitute sheet and modified filter (TSS1, n=44) and one switching to an RTP containing an enzyme-treated tobacco and modified filter (BT1, n=47).

Results: Assessment of the direction of change showed that up to the 100% of subjects experienced a decrease in levels of some BoEs. Between 49% and 64% of subjects in the switching groups were classified as having decreased levels of 3-hydroxy-1-methylpropylmercapturic acid (HMPMA) by the non-parametric criterion, whereas only 2%–6% had reduced levels of N-nitrosoanatabine (NAT). Of non-switchers, in 7%–14% of those smoking 1 mg ISO tar yield cigarettes increases were classified across all BoEs. RCVs highlighted patterns with more detail, showing that most changes occurred within 14 days of switching. Among smokers who switched to 6 mg RTPs, 40%, 44%, 6% and 15%, respectively, were classified as experiencing significant decreasing levels of HPMA, 3-hydroxypropylmercapturic acid, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and NAT, whereas in the two 1 mg switching groups 46%, 22%, 11% and 52% and 43%, 27%, 2% and 16% had decreased levels of the same biomarkers. Up to five subjects in the 6 mg non-switching group were classified as having increased levels of all BoEs.

Conclusions: Although we believe that is not possible to determine whether the observed changes in BoEs reflect biological relevance, the use of reference values enables assessment of changes in BoEs at the individual level. Estimates of the BoE variability between subjects might aid study design and setting minimum targets for smoke toxicant yields for future development of RTPs.

Racial differences in the relationship between tobacco dependence and nicotine and carcinogen exposure

AIMS

To investigate the relationships between tobacco dependence, biomarkers of nicotine and carcinogen exposure and biomarkers of nicotine and carcinogen exposure per cigarette in back and white smokers.

DESIGN, SETTING AND PARTICIPANTS

A total of 204 healthy black (n = 69) and white (n = 135) smokers were enrolled into two clinical studies.

MEASUREMENT

Nicotine equivalents (nicotine and its metabolites), 4-(methylnitrosamino)-1-(3)pyridyl-1-butanol (NNAL) and polycyclic aromatic hydrocarbon (PAH) metabolites were measured in urine. The Fagerström Test for Nicotine Dependence (FTND) and time to first cigarette (TFC) measured tobacco dependence.

FINDINGS

Average TFC and FTND for blacks and whites were not significantly different. Urine NNAL and nicotine equivalents increased with increasing FTND in whites but did not increase in blacks (race × FTND interaction, both P < 0.031). The interaction term was not significant for PAHs. An inverse relationship was seen between FTND and nicotine equivalents, NNAL and PAH metabolites per cigarette in blacks but remained flat in whites (race × FTND interaction, all P ≤ 0.039). Regardless of dependence (low dependence, TFC >15 minutes; high dependence, TFC ≤15 minutes), FTND and TFC were not correlated significantly with urine nicotine equivalents and carcinogen exposure in blacks. We found moderate correlations between FTND and TFC and nicotine equivalents and carcinogen exposure among whites of low dependence and non-significant correlations among whites of high dependence.

CONCLUSION

In the United States, tobacco dependence measures were related linearly to nicotine intake and carcinogen exposure in white but not in black smokers. The relationship between dependence measures and tobacco biomarkers in black smokers regardless of level of dependence resembled highly dependent white smokers.

Intra- and inter-individual variability in urinary nicotine excretion and plasma cotinine in adult cigarette smokers

Urinary nicotine equivalents (NE) and plasma cotinine are widely used as a biomarker for exposure to tobacco products, but there is limited information on intra- and inter-individual variability in the literature. Data were gathered from 13 randomized controlled clinical studies sponsored by Philip Morris USA, with study durations between 2 and 8 days for the short term (ST) and 3-12 months for the long term (LT) studies. Coefficients of variation (CV) were compared and a linear mixed model was used to partition the total study variability into inter- and intra-individual variability. In the ST and LT studies respectively, the root-mean-square (RMS) intra-individual CV was 19% and 29% for NE (mg/24 h); 19% and 33% for NE (mg/cig) and 13% and 22% for plasma cotinine. The RSM inter-individual CV was 38% and 38% for NE (mg/24h), 25% and 32% for NE (mg/cig) and 38% and 37% for plasma cotinine, in ST and LT study, respectively. Intra-individual CV was smaller in ST studies than in LT studies, and was significantly less than inter-individual CV in ST studies. Daily cigarette consumption alone could not explain all the variability in NE and plasma cotinine. The variability estimates could be used for clinical study design of clinical and developing regulatory guidance.

Exposure and kinetics of polycyclic aromatic hydrocarbons (PAHs) in cigarette smokers

Our study objectives were (1) to investigate the selectivity of polycyclic aromatic hydrocarbon (PAH) metabolites for tobacco smoke exposure and (2) to determine half-lives of PAH metabolites in smokers. There were 622 participants from the United States (US) and Poland, and of these, 70% were smokers. All subjects provided spot urine samples, and 125 smokers provided blood samples. Urinary PAH metabolite half-lives were determined in 8 smokers. In controlled hospital studies of 18 smokers, the associations between various measures of nicotine intake and urinary excretion of PAH metabolites were investigated. Plasma nicotine was measured by GC. LC-MS/MS was used to measure the plasma levels of cotinine and trans-3'-hydroxycotinine, and urine levels of nicotine and its metabolites, total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and PAH metabolites (2-naphthol, 1-, 2-, and 3-hydroxyfluorenes, 1-, 2-, 3-, and 4-hydroxyphenanthrenes, and 1-hydroxypyrene). Regardless of smoking status, PAH metabolite excretion was higher in Polish subjects than in US subjects (p-values <0.001). 1-Hydroxyfluorene exhibited the greatest difference between smokers and nonsmokers, with a 5-fold difference in Polish subjects and a 25-fold difference in US subjects, followed by 3- and 2-hydroxyfluorenes, 2-naphthol, and 1-hydroxypyrene. The differences for hydroxyphenanthrenes were small or nonsignificant. 1-Hydroxyfluorene had the highest correlation with urine nicotine equivalents (r = 0.77) and urine NNAL (r = 0.64). While the half-lives of PAH metabolites were <10 h in smokers, 1-hydroxyfluorene had the largest ratio of initial to terminal urine concentration (58.4 ± 38.6, mean ± SD) after smoking. Receiver Operating Characteristic (ROC) analysis of PAHs among Polish and US subjects further showed that hydroxyfluorenes are most highly discriminative of smokers from nonsmokers followed by 2-naphthol and 1-hydroxypyrene. In conclusion, hydroxyfluorenes, particularly 1-hydroxyfluorene, and 2-naphthol are more selective of tobacco smoke than 1-hydroxypyrene and hydroxyphenanthrenes. Characterization of hydroxyfluorene and 2-naphthol metabolites in urine may improve the characterization of PAHs from tobacco smoke and related disease risks among smokers and nonsmokers.

Nicotine: specific role in angiogenesis, proliferation and apoptosis

Nowadays, tobacco smoking is the cause of ~5-6 million deaths per year, counting 31% and 6% of all cancer deaths (affecting 18 different organs) in middle-aged men and women, respectively. Nicotine is the addictive component of tobacco acting on neuronal nicotinic receptors (nAChR). Functional nAChR, are also present on endothelial, haematological and epithelial cells. Although nicotine itself is regularly not referred to as a carcinogen, there is an ongoing debate whether nicotine functions as a 'tumour promoter'. Nicotine, with its specific binding to nAChR, deregulates essential biological processes like regulation of cell proliferation, apoptosis, migration, invasion, angiogenesis, inflammation and cell-mediated immunity in a wide variety of cells including foetal (regulation of development), embryonic and adult stem cells, adult tissues as well as cancer cells. Nicotine seems involved in fundamental aspects of the biology of malignant diseases, as well as of neurodegeneration. Investigating the biological effects of nicotine may provide new tools for therapeutic interventions and for the understanding of neurodegenerative diseases and tumour biology.

Factors affecting exposure to nicotine and carbon monoxide in adult cigarette smokers

Exposure to cigarette smoke among smokers is highly variable. This variability has been attributed to differences in smoking behavior as measured by smoking topography, as well as other behavioral and subjective aspects of smoking. The objective of this study was to determine the factors affecting smoke exposure as estimated by biomarkers of exposure to nicotine and carbon monoxide (CO). In a multi-center cross-sectional study of 3585 adult smokers and 1077 adult nonsmokers, exposure to nicotine and CO was estimated by 24h urinary excretion of nicotine and five of its metabolites and by blood carboxyhemoglobin, respectively. Number of cigarettes smoked per day (CPD) was determined from cigarette butts returned. Puffing parameters were determined through a CreSS® micro device and a 182-item adult smoker questionnaire (ASQ) was administered. The relationship between exposure and demographic factors, smoking machine measured tar yield and CPD was examined in a statistical model (Model A). Topography parameters were added to this model (Model B) which was further expanded (Model C) by adding selected questions from the ASQ identified by a data reduction process. In all the models, CPD was the most important and highest ranking factor determining daily exposure. Other statistically significant factors were number of years smoked, questions related to morning smoking, topography and tar yield categories. In conclusion, the models investigated in this analysis, explain about 30-40% of variability in exposure to nicotine and CO.

Relationship between biomarkers of cigarette smoke exposure and biomarkers of inflammation, oxidative stress, and platelet activation in adult cigarette smokers

BACKGROUND

Cigarette smoking is a risk factor for several diseases, including cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer, but the role of specific smoke constituents in these diseases has not been clearly established.

METHODS

The relationships between biomarkers of potential harm (BOPH), associated with inflammation [white blood cell (WBC), high sensitivity C-reactive protein (hs-CRP), fibrinogen, and von Willebrand factor (vWF)], oxidative stress [8-epi-prostaglandin F(2α) (8-epiPGF(2α))] and platelet activation [11-dehydro-thromboxin B(2) (11-dehTxB(2))], and machine-measured tar yields (grouped into four categories), biomarkers of exposure (BOE) to cigarette smoke: nicotine and its five metabolites (nicotine equivalents), 4-methylnitrosamino-1-(3-pyridyl)-1-butanol (total NNAL), carboxyhemoglobin, 1-hydroxypyrene, 3-hydroxypropylmercapturic acid, and monohydroxybutenyl-mercapturic acid, were investigated in 3,585 adult smokers and 1,077 nonsmokers.

RESULTS

Overall, adult smokers had higher levels of BOPHs than nonsmokers. Body mass index (BMI), smoking duration, tar category, and some of the BOEs were significant factors in the multiple regression models. Based on the F value, BMI was the highest ranking factor in the models for WBC, hs-CRP, fibrinogen, and 8-epiPGF(2α), respectively, and gender and smoking duration for 11-dehTxB(2) and vWF, respectively.

CONCLUSIONS

Although several demographic factors and some BOEs were statistically significant in the model, the R(2) values indicate that only up to 22% of the variability can be explained by these factors, reflecting the complexity and multifactorial nature of the disease mechanisms.

IMPACT

The relationships between the BOEs and BOPHs observed in this study may help with the identification of appropriate biomarkers and improve the design of clinical studies in smokers.

Racial differences in the relationship between number of cigarettes smoked and nicotine and carcinogen exposure

INTRODUCTION

Black smokers are reported to have higher lung cancer rates and greater tobacco dependence at lower levels of cigarette consumption compared to non-Hispanic White smokers. We studied the relationship between cigarettes per day (CPD) and biomarkers of nicotine and carcinogen exposure in Black and White smokers.

METHODS

In 128 Black and White smokers, we measured plasma nicotine and its main proximate metabolite cotinine, urine nicotine equivalents, 4-(methylnitrosamino)-1-(3)pyridyl-1-butanol (NNAL), and polycyclic aromatic hydrocarbon (PAH) metabolites.

RESULTS

The dose-response between CPD and nicotine equivalents, and NNAL and PAH was flat for Black but positive for White smokers (Race × CPD interaction, all ps < .05). Regression estimates for the Race × CPD interactions were 0.042 (95% CI 0.013-0.070), 0.054 (0.023-0.086), and 0.028 (0.004-0.052) for urine nicotine equivalents, NNAL, and PAHs, respectively. In contrast there was a strong correlation between nicotine equivalents and NNAL and PAH independent of race. Nicotine and carcinogen exposure per individual cigarette was inversely related to CPD. This inverse correlation was stronger in Black compared to White smokers and stronger in menthol compared to regular cigarette smokers (not mutually adjusted).

CONCLUSIONS

Our data indicate that Blacks on average smoke cigarettes differently than White smokers such that CPD predicts smoke intake more poorly in Black than in White smokers.

Menthol's potential effects on nicotine dependence: a tobacco industry perspective

OBJECTIVE

To examine what the tobacco industry knows about the potential effects menthol may have on nicotine dependence.

METHODS

A snowball strategy was used to systematically search the Legacy Tobacco Documents Library (http://legacy.library.ucsf.edu/) between 22 February and 29 April, 2010. Of the approximately 11 million documents available in the Legacy Tobacco Documents Library, the iterative searches returned tens of thousands of results. We qualitatively analysed a final collection of 309 documents relevant the effects of menthol on nicotine dependence.

RESULTS

The tobacco industry knows that menthol overrides the harsh taste of tobacco and alleviates nicotine's irritating effects, synergistically interacts with nicotine, stimulates the trigeminal nerve to elicit a 'liking' response for a tobacco product, and makes low tar, low nicotine tobacco products more acceptable to smokers than non-mentholated low delivery products.

CONCLUSION

Menthol is not only used in cigarettes as a flavour additive; tobacco companies know that menthol also has sensory effects and interacts with nicotine to produce tobacco products that are easier to smoke, thereby making it easier to expose smokers, especially those who are new and uninitiated, to the addictive power of nicotine.

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Urine menthol as a biomarker of mentholated cigarette smoking

OBJECTIVES

Menthol cigarettes are smoked by 27% of U.S. smokers, and there are concerns that menthol might enhance toxicity of cigarette smoking by increasing systemic absorption of smoke toxins. We measured urine menthol concentrations in relation to biomarkers of exposure to nicotine and tobacco carcinogens.

METHODS

Concentrations of menthol glucuronide (using a novel analytical method), nicotine plus metabolites (nicotine equivalents, NE), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and polycyclic aromatic hydrocarbon (PAH) metabolites were measured in the urine of 60 menthol and 67 regular cigarette smokers.

RESULTS

Urine menthol was measurable in 82% of menthol and 54% in regular cigarette smokers. Among menthol smokers, urine menthol was highly correlated with NE, NNAL, and PAHs. In a multiple regression model NE but not menthol was significantly associated with NNAL and PAHs.

CONCLUSIONS

Urine menthol concentration is a novel biomarker of exposure in menthol cigarette smokers, and is highly correlated with exposure to nicotine and carcinogens. Menthol is not independently associated with carcinogen exposure when nicotine intake is considered.

Human blood concentrations of cotinine, a biomonitoring marker for tobacco smoke, extrapolated from nicotine metabolism in rats and humans and physiologically based pharmacokinetic modeling

The present study defined a simplified physiologically based pharmacokinetic (PBPK) model for nicotine and its primary metabolite cotinine in humans, based on metabolic parameters determined in vitro using relevant liver microsomes, coefficients derived in silico, physiological parameters derived from the literature, and an established rat PBPK model. The model consists of an absorption compartment, a metabolizing compartment, and a central compartment for nicotine and three equivalent compartments for cotinine. Evaluation of a rat model was performed by making comparisons with predicted concentrations in blood and in vivo experimental pharmacokinetic values obtained from rats after oral treatment with nicotine (1.0 mg/kg, a no-observed-adverseeffect level) for 14 days. Elimination rates of nicotine in vitro were established from data from rat liver microsomes and from human pooled liver microsomes. Human biomonitoring data (17 ng nicotine and 150 ng cotinine per mL plasma 1 h after smoking) from pooled five male Japanese smokers (daily intake of 43 mg nicotine by smoking) revealed that these blood concentrations could be calculated using a human PBPK model. These results indicate that a simplified PBPK model for nicotine/cotinine is useful for a forward dosimetry approach in humans and for estimating blood concentrations of other related compounds resulting from exposure to low chemical doses.

Estimation of nicotine dose after low-level exposure using plasma and urine nicotine metabolites

BACKGROUND

We sought to determine the optimal plasma and urine nicotine metabolites, alone or in combination, to estimate the systemic dose of nicotine after low-level exposure.

METHODS

We dosed 36 nonsmokers with 100, 200, or 400 microg p.o. of deuterium-labeled nicotine (doses similar to exposure to secondhand smoke) daily for 5 days and then measured plasma and urine nicotine metabolites at various intervals over 24 hours.

RESULTS

The strongest correlations with nicotine dose were seen for the sum of four (cotinine+cotinine-glucuronide+trans-3'-hydroxycotinine+3HC-glucuronide) or six (including also nicotine+nicotine-glucuronide) of the major nicotine metabolites in 24-hour urine collection (r=0.96), with lesser correlations for these metabolites using spot urines corrected for creatinine at various times of day (r=0.72-0.80). The sum of plasma cotinine+trans-3'-hydroxycotine was more highly correlated with nicotine dose than plasma cotinine alone (r=0.82 versus 0.75).

CONCLUSIONS

Our results provide guidance for the selection of biomarkers to estimate the dose of nicotine taken in low-level (secondhand smoke) tobacco exposure.

IMPACT

This is probably relevant to active smoking as well.

Biomonitoring of urinary cotinine concentrations associated with plasma levels of nicotine metabolites after daily cigarette smoking in a male Japanese population

Human biomonitoring of plasma and urinary levels of nicotine, cotinine, and 3′-hydroxycotinine was conducted after daily cigarette smoking in a population of 92 male Japanese smokers with a mean age of 37 years who had smoked an average of 23 cigarettes per day for 16 years. Members of the population were genotyped for the nicotine-metabolizing enzyme cytochrome P450 2A6 (CYP2A6). The mean levels of nicotine, the levels of its metabolites cotinine and 3′-hydroxycotinine, and the sum of these three levels in subjects one hour after smoking the first cigarette on the sampling day were 20.1, 158, 27.7, and 198 ng/mL in plasma and 846, 1,020, 1,010, and 2,870 ng/mL in urine under daily smoking conditions. Plasma levels of 3′-hydroxycotinine and urinary levels of nicotine and 3′-hydroxycotinine were dependent on the CYP2A6 phenotype group, which was estimated from the CYP2A6 genotypes of the subjects, including those with whole gene deletion. Plasma cotinine levels were significantly correlated with the number of cigarettes smoked on the day before sampling (r = 0.71), the average number of cigarettes smoked daily (r = 0.58), and the Brinkman index (daily cigarettes × years, r = 0.48) under the present conditions. The sum of nicotine, cotinine, and 3′-hydroxycotinine concentrations in plasma showed a similar relationship to that of the plasma cotinine levels. Urinary concentrations of cotinine and the sum of nicotine metabolite concentrations also showed significant correlations with the plasma levels and the previous day’s and average cigarette consumption. The numbers of cigarettes smoked per day by two subjects with self-reported light smoking habits were predicted by measuring the urinary cotinine concentrations and using linear regression equations derived from above-mentioned data. These results indicate that biomonitoring of the urinary cotinine concentration is a good, easy-to-use marker for plasma levels of cotinine and the sum of nicotine metabolites in smokers independent of genetic polymorphism of CYP2A6.

A novel validated procedure for the determination of nicotine, eight nicotine metabolites and two minor tobacco alkaloids in human plasma or urine by solid-phase extraction coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry

A novel validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) procedure was developed and fully validated for the simultaneous determination of nicotine-N-beta-D-glucuronide, cotinine-N-oxide, trans-3-hydroxycotinine, norcotinine, trans-nicotine-1'-oxide, cotinine, nornicotine, nicotine, anatabine, anabasine and cotinine-N-beta-D-glucuronide in human plasma or urine. Target analytes and corresponding deuterated internal standards were extracted by solid-phase extraction and analyzed by LC-MS/MS with electrospray ionization (ESI) using multiple reaction monitoring (MRM) data acquisition. Calibration curves were linear over the selected concentration ranges for each analyte, with calculated coefficients of determination (R(2)) of greater than 0.99. The total extraction recovery (%) was concentration dependent and ranged between 52-88% in plasma and 51-118% in urine. The limits of quantification for all analytes in plasma and urine were 1.0 ng/mL and 2.5 ng/mL, respectively, with the exception of cotinine-N-beta-D-glucuronide, which was 50 ng/mL. Intra-day and inter-day imprecision were < or = 14% and < or = 17%, respectively. Matrix effect (%) was sufficiently minimized to < or = 19% for both matrices using the described sample preparation and extraction methods. The target analytes were stable in both matrices for at least 3 freeze-thaw cycles, 24 h at room temperature, 24 h in the refrigerator (4 degrees C) and 1 week in the freezer (-20 degrees C). Reconstituted plasma and urine extracts were stable for at least 72 h storage in the liquid chromatography autosampler at 4 degrees C. The plasma procedure has been successfully applied in the quantitative determination of selected analytes in samples collected from nicotine-abstinent human participants as part of a pharmacokinetic study investigating biomarkers of nicotine use in plasma following controlled low dose (7 mg) transdermal nicotine delivery. Nicotine, cotinine, trans-3-hydroxycotinine and trans-nicotine-1'-oxide were detected in the particular sample presented herein. The urine procedure has been used to facilitate the monitoring of unauthorized tobacco use by clinical study participants at the time of physical examination (before enrollment) and on the pharmacokinetic study day.

Population estimates for biomarkers of exposure to cigarette smoke in adult U.S. cigarette smokers

INTRODUCTION

There are about 4,800 different chemical constituents in cigarette smoke. Therefore, the total systemic exposure evaluation of the population of smokers to cigarette smoke is challenging. Measurement of biomarkers as surrogates of cigarette smoke constituents is a realistic approach to assess exposure.

OBJECTIVE

To estimate cigarette smoke exposure of the U.S. smoker population.

METHODS

Stratified, cross-sectional, multicenter design (39 sites in 31 states); 3,585 adult cigarette smokers and 1,077 nonsmokers. Biomarkers were determined from 24-hr urine collections or blood samples. Population estimates were generated by weighting sample data with weights from a large U.S. probability sample (Behavioral Risk Factor Surveillance System).

RESULTS

The adult smoker population estimates for tobacco-specific biomarkers were nicotine equivalents 13.3 mg/24 hr (SE 0.14), serum cotinine 184 ng/ml (1.8), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol 439 ng/24 hr (5.5). The population estimates for smokers and nonsmokers for nontobacco-specific biomarkers were 1-hydroxypyrene 317 (6.8) and 110 (7.1) ng/24 hr, 4-aminobiphenyl Hb adducts 43.1 (1.04) and 11.4 (1.5) pg/g Hb, carboxyhemoglobin 5.26(0.04) in percent of hemoglobin saturation and 1.45(0.02), 3-hydroxypropylmercapturic acid 2,030 (24) and 458 (17) microg/24 hr, monohydroxy-butenyl-mercapturic acid 3.61 (0.1) and 0.30 (0.02) microg/24 hr, and dihydroxy-butyl-mercapturic acid 556 (4.9) and 391 (5.5) microg/24 hr. On average, young adult smokers had lower exposure than older smokers; female smokers had lower exposure than males, and Black smokers had lower exposure than Whites.

DISCUSSION

This study estimated the population exposure to cigarette smoke constituents in adult U.S. smokers and identified significant differences between subpopulations. The data may serve as a reference for monitoring the impact of changes in cigarette consumption and the introduction of potentially reduced exposure cigarettes.

The relationship between smoking machine derived tar yields and biomarkers of exposure in adult cigarette smokers in the US

Comprehensive data on human exposure to smoke constituents from different machine-measured tar yield cigarettes is limited.

METHODS

This study used a stratified, cross-sectional, multi-center design to estimate biomarkers of exposure (BOE) from nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene, CO, acrolein, and 1,3-butadiene and their relationship to tar yield categories of cigarette in adult smokers in the U.S. 3625 adults smokers were enrolled into four tar categories < or =2.9 mg (T1), 3.0-6.9 mg (T2), 7.0-12.9 mg (T3), and > or =13.0mg (T4). Biomarkers were measured in blood (carboxyhemoglobin, 4-aminobiphenyl-hemoglobin (4-ABP-Hb)-adducts, serum cotinine) and 24h urine (nicotine and five metabolites, calculated as nicotine equivalents (NE), NNAL, 1-OH-pyrene, 3-HPMA, MHBMA and DHBMA). Data were analyzed using analysis of covariance (ANCOVA).

RESULTS

Tar was a significant factor for most biomarkers in the ANCOVA models. The largest least square mean differences between tar categories was 35% for NE per day, 28% for NE per cigarette, 36% for serum cotinine, 42% for NNAL per day, 29% for NNAL per cigarette, 26% for 1-OHP, 24% for COHb, 14% for 3-HPMA and 40% for 4-ABP-Hb. Variability in BOE ranged from 41% to 154% CV.

CONCLUSIONS

There was a statistically significant effect of machine-measured tar yield on most BOE, which were generally lower with lower tar yield.

A study to estimate and correlate cigarette smoke exposure in smokers in Germany as determined by filter analysis and biomarkers of exposure

A clinical study, conducted in Germany, compared two methods of estimating exposure to cigarette smoke. Estimates of mouth level exposure (MLE) to nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene and acrolein were obtained by chemical analysis of spent cigarette filters for nicotine content. Estimates of smoke constituent uptake were achieved by analysis of corresponding urinary biomarkers: for nicotine; total nicotine equivalents (nicotine, cotinine, trans-3'-hydroxycotinine plus their glucuronide conjugates), for NNK; (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) plus glucuronide, for pyrene; 1-hydroxy pyrene (1-OHP) plus glucuronide and for acrolein; 3-hydroxylpropyl-mercapturic acid (3-HPMA) plus the nicotine metabolite cotinine in plasma and saliva. Two hundred healthy volunteer subjects were recruited; 50 smokers of each of 1-2 mg, 4-6 mg and 9-10 mg ISO tar yield cigarettes and 50 non-smokers (NS). Smokers underwent two periods of home smoking, each followed by residence in a clinic. Smoking was permitted ad libitum, and spent cigarette filters, cigarette consumption data, 24h urine, as well as plasma and saliva samples were collected. Significant correlations (p<0.001) were found between MLE and the relevant biomarker for each smoke constituent. The Pearson correlation coefficients (r) were 0.83 (nicotine), 0.76 (NNK), 0.82 (acrolein) and 0.63 (pyrene). Mean MLE estimates for nicotine, NNK and pyrene showed a dose response in line with ISO tar yield smoked, with 10 mg > 4 mg >1 mg, and for acrolein 10 mg> 4 mg > *1mg (where * indicates not significant at 95% confidence level). The mean exposure estimates from biomarkers for nicotine, NNK and acrolein also showed a dose response in line with ISO tar yield with 10 mg > 4 mg > 1 mg > NS, and for pyrene 10 mg > *4 mg> 1 mg> NS. This study shows that estimates of exposure obtained by filter analysis and biomarkers of exposure correlate significantly over a wide range of smoke exposures and that filter analysis may provide a simple and effective alternative to biomarkers for estimating smokers' exposure.

Maternal personal exposure to airborne benzene and intrauterine growth

BACKGROUND

Studies relying on outdoor pollutants measures have reported associations between air pollutants and birth weight.

OBJECTIVE

Our aim was to assess the relation between maternal personal exposure to airborne benzene during pregnancy and fetal growth.

METHODS

We recruited pregnant women in two French maternity hospitals in 2005-2006 as part of the EDEN mother-child cohort. A subsample of 271 nonsmoking women carried a diffusive air sampler for a week during the 27th gestational week, allowing assessment of benzene exposure. We estimated head circumference of the offspring by ultrasound measurements during the second and third trimesters of pregnancy and at birth.

RESULTS

Median benzene exposure was 1.8 microg/m(3) (5th, 95th percentiles, 0.5, 7.5 microg/m(3)). Log-transformed benzene exposure was associated with a gestational age-adjusted decrease of 68 g in mean birth weight [95% confidence interval (CI), -135 to -1 g] and of 1.9 mm in mean head circumference at birth (95% CI, -3.8 to 0.0 mm). It was associated with an adjusted decrease of 1.9 mm in head circumference assessed during the third trimester (95% CI, -4.0 to 0.3 mm) and of 1.5 mm in head circumference assessed at the end of the second trimester of pregnancy (95% CI, -3.1 to 0 mm).

CONCLUSIONS

Our prospective study among pregnant women is one of the first to rely on personal monitoring of exposure; a limitation is that exposure was assessed during 1 week only. Maternal benzene exposure was associated with decreases in birth weight and head circumference during pregnancy and at birth. This association could be attributable to benzene and a mixture of associated traffic-related air pollutants.

A randomized, controlled exposure study in adult smokers of full flavor Marlboro cigarettes switching to Marlboro Lights or Marlboro Ultra Lights cigarettes

Rationale. To date no state-of-the-art clinical study has been conducted to address the question as to whether switching to lower tar cigarettes reduces exposure to smoke constituents in humans. Methods. Randomized, controlled, forced switching study in 225 adult smokers of full flavor Marlboro (MFF) cigarettes for 8 days with a 24-week follow-up. Subjects smoked MFF (a 15-mg Federal Trade Commission (FTC) tar cigarette) at baseline and were randomized to smoke 11-mg Marlboro Lights (ML) or 6-mg Marlboro Ultra Lights (MUL) cigarettes. Biomarkers of exposure to nicotine, 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene, CO, benzene, acrolein, and mutagenic substances were measured. Results. In the short-term phase, switching from MFF to ML showed statistically significant decreases in nicotine exposure (-13%) and non-significant increases in CO exposure (+6%), while switching from MFF to MUL showed statistically significant decreases in nicotine (-27%) and CO (-13%) exposure. Both nicotine and CO biomarkers trended similarly in the 24-week follow-up as in the short-term phase. The other biomarkers of cigarette smoke constituents followed the same trend as nicotine at the end of the 24-week follow-up. Conclusions. Switching smokers to lower FTC tar yield cigarettes, on average, reduces nicotine and other biomarkers considered surrogates of tar exposure.

A 12-month, randomized, controlled study to evaluate exposure and cardiovascular risk factors in adult smokers switching from conventional cigarettes to a second-generation electrically heated cigarette smoking system

This randomized, controlled, forced-switching, open-label, parallel-group study in 97 adult male and female smokers of conventional cigarettes evaluated biomarkers of tobacco smoke exposure and cardiovascular risk factors. After baseline measurements, smokers were either switched to a second-generation electrically heated cigarette smoking system (EHCSS) or continued smoking conventional cigarettes for 12 months. Biomarkers of exposure and cardiovascular risk factors were measured at 0.5, 1, 2, 3, 4, 5, 6, 9, and 12 months. There was a rapid and sustained reduction in all biomarkers of exposure after switching to the EHCSS, with statistically significant reductions from baseline in nicotine equivalents (-18%), plasma cotinine (-16%), total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (-73%), total 1-hydroxypyrene (-53%), urine mutagenicity (-52%), 4-aminobiphenyl hemoglobin adducts (-43%), carboxyhemoglobin AUC7-23 h (-80%), and 3-hydroxypropylmercapturic acid (-35%). These reductions in exposure in the EHCSS group were associated with statistically significant and pathophysiologically favorable changes in several cardiovascular risk factors, including white blood cell count (-0.78 x 10(3)/microL), hemoglobin (-0.16 g/dL), hematocrit (-0.44%), urine 11-dehydrothromboxane B2 (-374 ng/24 h), and high-density lipoprotein cholesterol (+5 mg/dL).