Metabolites of a tobacco-specific lung carcinogen in children exposed to secondhand or thirdhand tobacco smoke in their homes

Contamination of surfaces in children's homes with nicotine and the potent carcinogenic tobacco-specific nitrosamine NNK

BACKGROUND

Tobacco smoke exposure (TSE) through secondhand and thirdhand smoke is a modifiable risk factor that contributes to childhood morbidity. Limited research has assessed surface TSE pollution in children's environments as a potential source of thirdhand smoke exposure, and none have examined levels of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on surfaces.

OBJECTIVE

This study measured surface NNK and nicotine in children's homes and associations with sociodemographics and parent-reported TSE behaviors. We assessed correlations of surface NNK and nicotine with dust NNK, dust nicotine, and child cotinine.

METHODS

Home surface wipe NNK and nicotine data from 84 children who lived with smokers were analyzed. Tobit and simple linear regression analyses were conducted to assess associations of surface NNK and nicotine with child characteristics. Spearman's (ρ) correlations assessed the strength of associations between environmental markers and child cotinine.

RESULTS

Nearly half (48.8%) of children's home surfaces had detectable NNK and 100% had detectable nicotine. The respective geometric means (GMs) of surface NNK and nicotine loadings were 14.0 ng/m2 and 16.4 µg/m2. Surface NNK positively correlated with surface nicotine (ρ = 0.54, p < 0.001) and dust NNK (ρ = 0.30, p = 0.020). Surface nicotine positively correlated with dust NNK (ρ = 0.42, p < 0.001) and dust nicotine (ρ = 0.24, p = 0.041). Children with household incomes ≤$15,000 had higher surface NNK levels (GM = 18.7 ng/m2, p = 0.017) compared to children with household incomes >$15,000 (GM = 7.1 ng/m2). Children with no home smoking bans had higher surface NNK (GM = 18.1 ng/m2, p = 0.020) and surface nicotine (GM = 17.7 µg/m2, p = 0.019) levels compared to children with smoking bans (GM = 7.5 ng/m2, 4.8 µg/m2, respectively).

IMPACT

Although nicotine on surfaces is an established marker of thirdhand smoke pollution, other thirdhand smoke contaminants have not been measured on surfaces in the homes of children living with smokers. We provide evidence that the potent carcinogenic tobacco-specific nitrosamine NNK was detectable on surfaces in nearly half of children's homes, and nicotine was detectable on all surfaces. Surface NNK was positively correlated with surface nicotine and dust NNK. Detectable surface NNK levels were found in homes with indoor smoking bans, indicating the role of NNK as a persistent thirdhand smoke pollutant accumulating on surfaces as well as in dust.

Protocol for CARES-HAPIN: an ambidirectional cohort study on exposure to environmental tobacco smoke and risk of early childhood caries

INTRODUCTION

Prenatal and postnatal exposure to environmental tobacco smoke (ETS) has been linked with early childhood caries (ECC), but the specific molecular mechanisms and pathways remain largely unknown. The Caries Risk from exposure to Environmental tobacco Smoke (CARES) within the Household Air Pollution Intervention Network (HAPIN) study aims to establish the association between ETS and ECC by employing epidemiological and novel biomarker-based approaches. Here, we outline the overall design and rationale of the project.

METHODS AND ANALYSIS

We will leverage the infrastructure and data from the HAPIN trial (India) to mount the CARES study. In this ambidirectional cohort study, children (n=735, aged: 3-5 years) will undergo ECC examination by a trained dentist using standard criteria and calibrated methods. Structured questionnaires will be used to gather information on sociodemographic variables, dietary habits, oral hygiene, oral health-related quality of life and current exposure to ETS. We will collect non-invasive or minimally invasive biospecimens (i.e., saliva, buccal cells, dried blood spots and urine) from a subset of HAPIN children (n=120) to assess a battery of biomarkers indicative of exposure to ETS, early biological effect and epigenetic modifications. Both self-reported and objective measures of ETS exposure collected longitudinally during in utero and early postnatal periods will be accessed from the HAPIN database. We will apply current science data techniques to assess the association and interrelationships between ETS, ECC, and multiple biomarkers.

ETHICS AND DISSEMINATION

Information gathered in this research will be published in peer-reviewed journals and summaries will be shared with the key stakeholders as well as patients and their parents/guardians involved in this study. Sri Ramachandra Institute of Higher Education and Research Ethics Board has approved the study protocol (IEC-NI22/JUL/83/82).

TRIAL REGISTRATION NUMBER

NCT02944682.

[Allergenic and chemical pollutants of indoor environments and asthma: Characterization, assessment and eviction]

The environment of an asthmatic patient can contain numerous sources of pollutants that degrade the quality of indoor air and have major repercussions on the occurrence and control of asthma. Assessment and improvement of the quality of indoor air should be assigned a major role in pneumology and allergology consultations. Characterization of an asthmatic's environment entails a search for biological pollutants with mite allergens, mildew, and allergens resulting from the proximity of pets. It is important to evaluate the chemical pollution represented by exposure to volatile organic compounds, which are increasingly present in our lodgings. Active or second-hand smoking must in all circumstances be sought out and quantified. Assessment of the environment is mediated by several methods, of which the application depends not only on the pollutant sought out, but also on enzyme-linked immunosorbent assay (ELISA), which has an essential role in quantification of biological pollutants. Attempts at expulsion of the different indoor environment pollutants is mediated by indoor environment advisors, whose efforts are aimed at obtaining reliable evaluation and control of indoor air. Implemented as a form of tertiary prevention, their methods are conducive to improved asthma control, in adults as well as children.

Distinguishing Exposure to Secondhand and Thirdhand Tobacco Smoke among U.S. Children Using Machine Learning: NHANES 2013-2016

While the thirdhand smoke (THS) residue from tobacco smoke has been recognized as a distinct public health hazard, there are currently no gold standard biomarkers to differentiate THS from secondhand smoke (SHS) exposure. This study used machine learning algorithms to assess which combinations of biomarkers and reported tobacco smoke exposure measures best differentiate children into three groups: no/minimal tobacco smoke exposure (NEG); predominant THS exposure (TEG); and mixed SHS and THS exposure (MEG). Participants were 4485 nonsmoking 3-17-year-olds from the National Health and Nutrition Examination Survey 2013-2016. We fitted and tested random forest models, and the majority (76%) of children were classified in NEG, 16% were classified in TEG, and 8% were classified in MEG. The final classification model based on reported exposure, biomarker, and biomarker ratio variables had a prediction accuracy of 95%. This final model had prediction accuracies of 100% for NEG, 88% for TEG, followed by 71% for MEG. The most important predictors were the reported number of household smokers, serum cotinine, serum hydroxycotinine, and urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). In the absence of validated biomarkers specific to THS, comprehensive biomarker and questionnaire data for tobacco smoke exposure can distinguish children exposed to SHS and THS with high accuracy.

Public Health Burden of Secondhand Smoking: Case Reports of Lung Cancer and a Literature Review

Secondhand smoke (SHS), composed of mainstream and sidestream smoke, is a known human carcinogen. It contains a variety of harmful substances at even higher concentrations than mainstream smoke itself, which is inhaled during firsthand smoking. Exposure to SHS, affecting more than a third of the worldwide population, increases the likelihood of lung cancer by roughly 30%, with specific contributions depending on the histological type of cancer. This study aimed to present the harmful potential of SHS through case reports and describe the burden of SHS via a literature review. From a collection of lung cancer case reports occurring in never smokers from the Olomouc district over the last 10 years, 2 cases with no risk factors for lung cancer except for significant exposure to SHS were identified. Both cases were of young women who lived in households where their parents smoked during childhood. They suffered from rarer histological types of lung cancer in which the association with SHS has not yet been analyzed. As the literature confirms, SHS has the most adverse effects in individuals exposed during childhood. It is necessary to both take measures to reduce the prevalence of SHS, especially among children in households and pay due attention to the smoking history of patients, including current and previous exposure to SHS, when obtaining anamnestic data. Furthermore, the effect of SHS on rarer histological types of lung cancer should be studied.

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.

Genetic Polymorphism of Cyp2a6 and Cyp2a13 Genes and Environmental Tobacco Smoke Induced Lung Cancer Risk in Indonesian Female Never Smokers

BACKGROUND: The presence of nicotine metabolite in the urine of subjects exposed to tobacco smoke represents the nicotine metabolism activity in environmental tobacco smokers. CYP2A6 and CYP2A13 are known as the main enzymes responsible for nicotine metabolism and xenobiotic activity in tobacco smoke-related lung cancer. AIM: The aim of this study is to analyze the relationship between genetic polymorphism of CYP26 and CYP2A13 genes and environmental tobacco smoke-induced lung cancer risk in Indonesian females never smoker. METHODS: This is a case-control study with two-stage of distinguishing polymorphism detection. Restriction fragment length polymorphism polymerase chain reaction from venous blood extraction was performed to examine the CYP2A6 and CYP2A13 polymorphism. Logistic regression test in Epi Info-7 software was carried out to examine genetic polymorphism of CYP2A6 and CYP2A13 genes and environmental tobacco smoke-induced lung cancer risk in Indonesian female never smokers. RESULTS: A total of 203 participants enrolled in this study with the first stage of CYP2A6 polymorphism involved 101 subjects showed no significant correlation between the genotypes of CYP2A6 and the incidence of lung cancer. On the other hand, there was a significant correlation between genotypes of CYP2A13 and the incidence of lung cancer (p < 0.05). People with the genotype CT have a 2.7 higher risk for developing lung cancer compare with genotype CC. Allele *1B was the most common allele in CYP2A6. Allele C has more frequencies and has 0.62 times the risk for developing lung cancer compared with allele T with a wide range of confidence intervals (0.73–3.52). CONCLUSIONS: There was a significant correlation between polymorphism CYP213 with the incidence of lung cancer among female lung cancer never smoker. However, the results show no significant relationship between CYP2A6 genetic polymorphism and lung cancer incidence.

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.

Public awareness of environmental risk factors of cancer and attitude towards its prevention among the Lebanese general population

Introduction

Since the majority of cancers occur as a result of modifiable risk factors, cancer is being seen more as a preventable disease. The primary objective of our study was to assess the level of awareness of environmental risk factors of cancer among the Lebanese general population. The secondary objective focused on identifying the predictors of the preventability of the disease.

Methods

We conducted a cross-sectional study between June and July 2020. An online questionnaire was used to collect data pertaining to the knowledge of environmental risk factors of cancer, source of information and personal practice of the participants. Bivariate and multivariate analyzes were performed.

Results

About 387 respondents agreed to participate in the study. The study showed low awareness regarding infectious agents, lifestyle, diet and many work exposures. The predictors of the attitude of respondents regarding the preventability of cancer were: believing that cancer has an environmental cause (p=.014), not having a healthy lifestyle (p = 0.004), not smoking waterpipe (p = 0.023), being single (p = 0.013), and having a university degree (p = 0.049).

Conclusions

Efforts should be made to improve awareness of the cancer risk factors regarding infectious agents, lifestyle, diet and many work exposures. This can also be followed by further studies assessing the impact of these community and governmental cancer prevention initiatives on cancer risk factors level of awareness.

Validity and reliability of Turkish version of Beliefs About Third-Hand Smoke Scale: BATHS-T

OBJECTIVE

Exposure to third-hand smoke (THS) poses health risk, especially for children. THS is mostly ignored in Turkey. The aim of this study is to adapt the Beliefs about Third-Hand Smoke (BATHS) scale to Turkish.

METHODS

The BATHS scale consists of 9 items, and the data collected from 273 people was considered sufficient for analyses in this methodological study. The BATHS scale is translated into Turkish and confirmatory factor analysis (CFA) was performed for the construct validity analysis of the scale.

RESULTS

The correlation between the overall BATHS scale and its two sub-dimensions was 0.937 (p < 0.001), and the correlation between the health and persistence sub-dimensions was 0.775 (p < 0.001). Since there was a statistically positive and highly significant relationship, the adapted BATHS scale was considered structurally compatible with the sub-dimensions. The reliability value of the entire scale is 0.90. Test-retest correlation values between the health and persistence dimensions were between 0.745 and 0.960, the values obtained were above 0.70 and had a statistically positive and high level of significant relationship (p < 0.001).

CONCLUSIONS

It is concluded that the Turkish version of the BATHS scale is reliable and valid. This scale will allow further research and training on third-hand smoke exposure. Tobacco control programmes success will improve.

Applying Tobacco, Environmental, and Dietary-Related Biomarkers to Understand Cancer Etiology and Evaluate Prevention Strategies

Many human cancers are caused by environmental and lifestyle factors. Biomarkers of exposure and risk developed by our team have provided critical data on internal exposure to toxic and genotoxic chemicals and their connection to cancer in humans. This review highlights our research using biomarkers to identify key factors influencing cancer risk as well as their application to assess the effectiveness of exposure intervention and chemoprevention protocols. The use of these biomarkers to understand individual susceptibility to the harmful effects of tobacco products is a powerful example of the value of this type of research and has provided key data confirming the link between tobacco smoke exposure and cancer risk. Furthermore, this information has led to policy changes that have reduced tobacco use and consequently, the tobacco-related cancer burden. Recent technological advances in mass spectrometry led to the ability to detect DNA damage in human tissues as well as the development of adductomic approaches. These new methods allowed for the detection of DNA adducts in tissues from patients with cancer, providing key evidence that exposure to carcinogens leads to DNA damage in the target tissue. These advances will provide valuable insights into the etiologic causes of cancer that are not tobacco-related.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."

Toxic effects of 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal on the reproduction of female mice

Cigarette smoke can affect female reproductive health by causing follicle destruction and oocyte dysfunction. Third-hand smoke has received increasing attention as a public health issue. However, the effects of third-hand smoke on the female reproductive system, particularly the ovaries, remain unclear. 1-(N-methyl-N-nitrosamino)-1-(3-pyridinyl)-4-butanal (NNA) can be used as a biomarker of third-hand smoke. We studied the in vivo toxic effects of NNA on mice ovaries and offspring development. Three-week-old premature female mice were exposed to NNA at two different concentrations (0.075 μg/kg and 0.15 μg/kg body weight) and tap water (blank control) and diluted dimethylsulfoxide (solvent control) for 30 days. We found that oral administration of NNA (0.075 μg/kg and 0.15 μg/kg) significantly reduced ovary weight (the 0.15 μg/kg group was reduced to 18.69% ± 0.89%) and ovarian follicle number (reduced by about 30%) (p < 0.05). Consumption of 0.15 μg/kg NNA reduced the survival rate of superovulated oocytes from 91.36% to 60.55% (p < 0.05). In addition, treated female mice in each group were mated with normal male mice to observe the effects of NNA on the F1 offspring, and during mating and lactation, all groups were given tap water. Two different concentrations of NNA exposure also significantly reduced body weight and impaired ear opening, tooth eruption and eye opening in F1 offspring, especially those exposed to 0.15 μg/kg NNA (p < 0.05). Our study suggested that NNA exposure had toxic effects on the reproductive health of female mice and their offspring. The results obtained may help evaluate the risks of third-hand smoke to women's reproductive health and to the health of their offspring.

Thirdhand smoke: Genotoxicity and carcinogenic potential

Thirdhand smoke (THS), the residual tobacco smoke remaining in the environment after tobacco has been smoked, represents a hidden and underestimated public health hazard. Evidence supports its widespread presence in indoor environments. Exposure to secondhand smoke (SHS), a precursor of THS, has been well documented as a risk factor for human cancers, especially lung cancer. However, the concept of THS as a distinct entity that poses health risks for small children has developed only recently and the associations of THS with cancer risk and other chronic diseases are poorly understood due to limited numbers of studies to date. In this perspective, we mainly summarize all published studies on the genotoxicity and carcinogenic potential of THS exposure. These studies begin to fill the knowledge gap in our understanding of cancer risk of THS. Accumulating data from existing and future studies will help reduce the tobacco-related cancer incidence through changes in lifestyle and tobacco control policies.

Children are particularly vulnerable to environmental tobacco smoke exposure: Evidence from biomarkers of tobacco-specific nitrosamines, and oxidative stress

BACKGROUND

Worldwide, smoking is a major public health problem, with exposure to environmental tobacco smoke (ETS) affecting both smokers, and passive smokers, including children. Despite ETS also describing secondhand, and thirdhand smoke (SHS, and THS respectively), the health effects of exposure to passive smoking via these sources are not fully understood, particularly in children. Although cotinine, the primary proximate metabolite of nicotine, has been widely used as a biomarker of ETS exposure, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), the metabolite of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), provides a uniquely important contribution, both as a biomarker of exposure, and as a specific risk indicator for pulmonary carcinogenesis.

METHODS

We used LC-MS/MS to study NNK metabolites, cotinine, and 8-oxo-7,8-dihydro-2'-deoxyguanosine (a biomarker of oxidative stress), in the urine of 110 non-smoking adults (age range: 23-62) and 101 children (age range: 9-11), exposed to ETS.

RESULTS

In our study of passive smoking adults, and children exposed to ETS, we showed that although the children had a similar urinary level of cotinine compared to the adults, the children had approximately two times higher levels of urinary total NNAL (P = 0.002), and free NNAL (P = 0.01), than adults. The children also had three times lower ability to detoxify NNK than adults (P < 0.001). Furthermore, the children showed 1.5 times higher ratio of total NNAL/cotinine than adults (P = 0.01), implying that THS is another important source of ETS in this population. Furthermore, ETS exposure in children appeared to lead to an increase in levels of oxidative stress.

CONCLUSIONS

Taken together, our results demonstrate that, in children, THS may play an important role in the ETS exposure, and that children are at particular risk of ETS-induced health effects.

Update on thirdhand smoke: A comprehensive systematic review

OBJECTIVE

The objective of this study is to perform a comprehensive review of the literature about thirdhand smoke (THS).

METHODS

Systematic review of all aspects of THS. Standard methodological procedures were used to search the following databases through April 2018: MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science (WOS) in Indo-European languages. To identify published grey literature, the first 200 hits from Google Scholar™ were evaluated. Clinical trial databases, conference proceedings, and reference lists from the identified articles were also searched. Two unblinded review authors independently assessed trials for inclusion in the review. These same reviewers also extracted study data in accordance with PRISMA guidelines. The study protocol was registered with PROSPERO (CRD42018083619).

RESULTS

Sixty-eight articles were included in this systematic review. Of these, 28 analyzed the concentration of nicotine as a component of THS (the most commonly-used method to measure THS in those studies was chromatography, followed by the mass spectrometry), 21 evaluated the exposure and impact of THS on health (11 studies analyzed the effect of THS in cells [human and animal], 4 in animals, 1 in adults, and 5 in children), 16 investigated the beliefs, behaviours, and policies related to THS, and 3 evaluated other aspects such as THS in e-cigarettes or hookahs. In these 68 studies, THS was determined by measuring the following components: nicotine (30 studies), nitrosamines (17 studies) and cotinine (15 studies). The findings from most of these studies suggest a potential health impact of THS exposure (i.e.: cytotoxicity, metabolic alterations in metabolism, in glycemia; or cell structure; alterations in liver, lung, skin and behaviour in mice), and low awareness about the risks of THS among the general population.

CONCLUSIONS

Numerous specific biomarkers of THS were evaluated, with the most common being nicotine, nitrosamines, and cotinine. The most common method of preparing THS dust samples were cotton wipes, while chromatography, used alone or coupled with mass spectrometry, was the most common analytical technique. We have tried to establish common bases after reviewing all the current literature of the THS although, there is great heterogeneity between the studies and we have not always succeeded. The studies in this review demonstrate the harmful effects of THS on health in cells, in animal models, and in people including children. However, in people, the long-term effects remain unknown and more research is needed. These studies show that knowledge about THS and its potential harmful effects are poorly understood among the general population. For this reason, THS should receive greater emphasis in education and awareness policies.

Biomarkers of Exposure in ENDS Users, Smokers, and Dual Users of American Indian Descent

Objectives

We measured biomarkers of exposure among American Indian (AI) ENDS users, smokers, and dual users.

Methods

Urine was analyzed for total nicotine equivalents (TNE) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol(NNAL). Expired-air carbon monoxide (CO) was collected. Two analyses were performed. "CO analysis" included smokers and dual users whose CO was ≥ 6 ppm and ENDS users whose CO was < 6 ppm. "NNAL analysis" included smokers and dual users whose NNAL was ≥ 47.3 pg/mg, and ENDS users whose NNAL was < 47.3 pg/mg. Biomarkers were summarized by geometric means (GM) and compared with nonparametric tests.

Results

In both analyses, TNE was no different across the groups, and NNAL and CO were lower in ENDS users. In the NNAL analysis the GM of NNAL was 261.4, 6.1, and 228.0 pg/mg among smokers, ENDS users, and dual users (p < .001). Also in the NNAL analysis, the GM of CO was 14.7, 2.4, and 16.8 ppm among smokers, ENDS users, and dual users (p < .001).

Conclusions

ENDS users did not differ in nicotine and had lower exposure to a lung carcinogen and a cardiovascular toxicant than smokers or dual users. Dual users and smokers did not differ in biomarker levels. Results should be used to inform tribal regulations and to educate the AI community on ENDS.

Potential Co-Factor Role of Tobacco Specific Nitrosamine Exposures in the Pathogenesis of Fetal Alcohol Spectrum Disorder

BACKGROUND

Cerebellar developmental abnormalities in Fetal Alcohol Spectrum Disorder (FASD) are linked to impairments in insulin signaling. However, co-morbid alcohol and tobacco abuses during pregnancy are common. Since smoking leads to tobacco specific Nitrosamine (NNK) exposures which have been shown to cause brain insulin resistance, we hypothesized that neurodevelopmental abnormalities in FASD could be mediated by ethanol and/or NNK.

METHODS

Long Evans rat pups were intraperitoneal (IP) administered ethanol (2 g/kg) on postnatal days (P) 2, 4, 6 and/or NNK (2 mg/kg) on P3, P5, and P7 to simulate third trimester human exposures. The Cerebellar function, histology, insulin and Insulin-like Growth Factor (IGF) signaling, and neuroglial protein expression were assessed.

RESULTS

Ethanol, NNK and ethanol+NNK groups had significant impairments in motor function (rotarod tests), abnormalities in cerebellar structure (Purkinje cell loss, simplification and irregularity of folia, and altered white matter), signaling through the insulin and IGF-1 receptors, IRS-1, Akt and GSK-3β, and reduced expression of several important neuroglial proteins. Despite similar functional effects, the mechanisms and severity of NNK and ethanol+NNK induced alterations in cerebellar protein expression differed from those of ethanol.

CONCLUSIONS

Ethanol and NNK exert independent but overlapping adverse effects on cerebellar development, function, insulin signaling through cell survival, plasticity, metabolic pathways, and neuroglial protein expression. The results support the hypothesis that tobacco smoke exposure can serve as a co-factor mediating long-term effects on brain structure and function in FASD.

Exposure and Metabolic Activation Biomarkers of Carcinogenic Tobacco-Specific Nitrosamines

Lung cancer is the leading cause of cancer death in the world, and cigarette smoking is its main cause. Oral cavity cancer is another debilitating and often fatal cancer closely linked to tobacco product use. While great strides have been made in decreasing tobacco use in the United States and some other countries, there are still an estimated 1 billion men and 250 million women in the world who are cigarette smokers and there are hundreds of millions of smokeless tobacco users, all at risk for cancer. Worldwide, lung cancer kills about three people per minute. This Account focuses on metabolites and biomarkers of two powerful tobacco-specific nitrosamine carcinogens, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN), considered to be among the main causes of lung cancer and oral cavity cancer in people who use tobacco products. Three properties of NNK and NNN are critical for successful biomarker studies: they are present in all tobacco products, they are tobacco-specific and are not found in any other product, and they are strong carcinogens. NNK and NNN are converted in humans to urinary metabolites that can be quantified by mass spectrometry as biomarkers of exposure to these carcinogens. They are also metabolized to diazonium ions and related electrophiles that react with DNA to form addition products that can be detected and quantified by mass spectrometry. These urinary metabolites and DNA addition products can serve as biomarkers of exposure and metabolic activation, respectively. The biomarkers of exposure, in particular the urinary NNK metabolites 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides, have been extensively applied to document tobacco-specific lung carcinogen uptake in smokers and nonsmokers exposed to secondhand tobacco smoke. Highly sensitive mass spectrometric methods have been developed for quantitative analysis of these NNK metabolites as well as metabolites of NNN in human urine, blood, and toenails. Urinary and serum NNAL have been related to lung cancer risk, and urinary NNN has been related to esophageal cancer risk in prospective epidemiology studies. These results are consistent with carcinogenicity studies of NNK, NNAL, and NNN in rats, which show that NNK and NNAL induce mainly lung tumors, while NNN causes tumors of the esophagus and oral cavity. Biomarkers of metabolic activation of NNK and NNN applied in human studies include the metabolism of deuterium labeled substrates to distinguish NNK and NNN metabolism from that of nicotine and the determination of DNA and hemoglobin adducts in tissues, blood, and oral cells from people exposed to tobacco products. As these methods are continually improved in parallel with the ever increasing sensitivity and selectivity of mass spectrometers, development of a comprehensive biomarker panel for identifying tobacco users at high risk for cancer appears to be a realistic goal. Targeting high risk individuals for smoking cessation and cancer surveillance can potentially decrease the risk of developing fatal cancers.

The Relation between Exposure to Environmental Tobacco Smoke and the Quantity of Cotinine in the Urine of School Children in Taif City, Saudi Arabia

Environmental tobacco smoke (ETS) is a major public health problem for all ages. Despite the high prevalence of smoking among the Saudi population, there is limited information about levels of urinary cotinine in Saudi children exposed to SHS. The aim of the study was to assess the exposure of schoolchildren to ETS, and measure their urinary cotinine levels. Multistage cluster sampling was carried out, where schoolchildren from 4 schools were randomly chosen from primary schools in Taif city. A questionnaire including questions on SHS exposure and smoking rules in the residence were sent to students parents/guardians. Urine samples were taken and analyzed for total cotinine using chemiluminescent immunoassay. Of the studied children, 38.4% had a smoking father, 61.8%, 41.2% and 49.3% of them were exposed to ETS indoors, outdoors and both indoors and outdoors respectively. The mean urinary cotinine was significantly higher among children exposed to ETS compared to unexposed children. Urinary cotinine levels in children with both indoor and outdoor exposure was significantly higher compared with its level in children with single exposure. A significant positive correlation was found between urinary cotinine concentrations and the number of cigarette packs smoked by parents, and the number of smokers in the residence. The mean urinary cotinine level was significantly higher in children who reported no smoking rules at the residence.. The study revealed a high exposure of Saudi children to ETS. An antismoking media awareness campaign on the harmful effects of ETS should be carried out, in addition to family counseling programs targeted to parents to protect their children from ETS.

European Code against Cancer, 4th Edition: Tobacco and cancer

Tobacco use, and in particular cigarette smoking, is the single largest preventable cause of cancer in the European Union (EU). All tobacco products contain a wide range of carcinogens. The main cancer-causing agents in tobacco smoke are polycyclic aromatic hydrocarbons, tobacco-specific N-nitrosamines, aromatic amines, aldehydes, and certain volatile organic compounds. Tobacco consumers are also exposed to nicotine, leading to tobacco addiction in many users. Cigarette smoking causes cancer in multiple organs and is the main cause of lung cancer, responsible for approximately 82% of cases. In 2012, about 313,000 new cases of lung cancer and 268,000 lung cancer deaths were reported in the EU; 28% of adults in the EU smoked tobacco, and the overall prevalence of current use of smokeless tobacco products was almost 2%. Smokeless tobacco products, a heterogeneous category, are also carcinogenic but cause a lower burden of cancer deaths than tobacco smoking. One low-nitrosamine product, snus, is associated with much lower cancer risk than other smokeless tobacco products. Smoking generates second-hand smoke (SHS), an established cause of lung cancer, and inhalation of SHS by non-smokers is still common in indoor workplaces as well as indoor public places, and more so in the homes of smokers. Several interventions have proved effective for stopping smoking; the most effective intervention is the use of a combination of pharmacotherapy and behavioural support. Scientific evidence leads to the following two recommendations for individual action on tobacco in the 4th edition of the European Code Against Cancer: (1) "Do not smoke. Do not use any form of tobacco"; (2) "Make your home smoke-free. Support smoke-free policies in your workplace".

Protecting Children From Tobacco, Nicotine, and Tobacco Smoke

This technical report serves to provide the evidence base for the American Academy of Pediatrics' policy statements "Clinical Practice Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke" and "Public Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke." Tobacco use and involuntary exposure are major preventable causes of morbidity and premature mortality in adults and children. Tobacco dependence almost always starts in childhood or adolescence. Electronic nicotine delivery systems are rapidly gaining popularity among youth, and their significant harms are being documented. In utero tobacco smoke exposure, in addition to increasing the risk of preterm birth, low birth weight, stillbirth, placental abruption, and sudden infant death, has been found to increase the risk of obesity and neurodevelopmental disorders. Actions by pediatricians can help to reduce children's risk of developing tobacco dependence and reduce children's involuntary tobacco smoke exposure. Public policy actions to protect children from tobacco are essential to reduce the toll that the tobacco epidemic takes on our children.

No impact of passive smoke on the somatic profile of lung cancers in never-smokers

EGFR and HER2 mutations and ALK rearrangement are known to be related to lung cancer in never-smokers, while KRAS, BRAF and PIK3CA mutations are typically observed among smokers. There is still debate surrounding whether never-smokers exposed to passive smoke exhibit a “smoker-like” somatic profile compared with unexposed never-smokers.

Passive smoke exposure was assessed in the French BioCAST/IFCT-1002 never-smoker lung cancer cohort and routine molecular profiles analyses were compiled.

Of the 384 patients recruited into BioCAST, 319 were tested for at least one biomarker and provided data relating to passive smoking. Overall, 219 (66%) reported having been exposed to passive smoking. No significant difference was observed between mutation frequency and passive smoke exposure (EGFR mutation: 46% in never exposed versus 41% in ever exposed; KRAS: 7% versus 7%; ALK: 13% versus 11%; HER2: 4% versus 5%; BRAF: 6% versus 5%; PIK3CA: 4% versus 2%). We observed a nonsignificant trend for a negative association between EGFR mutation and cumulative duration of passive smoke exposure. No association was found for other biomarkers.

There is no clear association between passive smoke exposure and somatic profile in lifelong, never-smoker lung cancer.

Potential contributions of the tobacco nicotine-derived nitrosamine ketone (NNK) in the pathogenesis of steatohepatitis in a chronic plus binge rat model of alcoholic liver disease

AIMS

Alcoholic liver disease (ALD) is linked to binge drinking and cigarette smoking. Heavy chronic ± binge alcohol, or low-level exposures to dietary nitrosamines cause steatohepatitis with insulin resistance and oxidative stress in animal models. This study examines hepatotoxic effects of sub-mutagenic exposures to tobacco-specific nitrosamine (NNK) in relation to ALD.

METHODS

Long Evans rats were fed liquid diets containing 0 or 26% (caloric) ethanol (EtOH) for 8 weeks. In Weeks 3 through 8, rats were treated with NNK (2 mg/kg) or saline by i.p. injection, 3×/week, and in Weeks 7 and 8, EtOH-fed rats were binge-administered 2 g/kg EtOH 3×/week; controls were given saline.

RESULTS

EtOH ± NNK caused steatohepatitis with necrosis, disruption of the hepatic cord architecture, ballooning degeneration, early fibrosis, mitochondrial cytopathy and ER disruption. Severity of lesions was highest in the EtOH+NNK group. EtOH and NNK inhibited insulin/IGF signaling through Akt and activated pro-inflammatory cytokines, while EtOH promoted lipid peroxidation, and NNK increased apoptosis. O(6)-methyl-Guanine adducts were only detected in NNK-exposed livers.

CONCLUSION

Both alcohol and NNK exposures contribute to ALD pathogenesis, including insulin/IGF resistance and inflammation. The differential effects of EtOH and NNK on adduct formation are critical to ALD progression among alcoholics who smoke.

Australian and New Zealand Indigenous mothers' report respect for smoking bans in homes

BACKGROUND

There is limited data about the reasons behind residential rules to reduce environmental tobacco smoke (ETS) exposure or the establishment or enforcement of such rules in Indigenous populations.

AIM

We aimed to gain an understanding of smokefree rules around Australian and New Zealand (NZ) Indigenous infants.

METHOD

This was a qualitative study nested within a randomised controlled trial that aimed to test the efficacy of a family-centred tobacco control programme about environmental tobacco smoke (ETS) to improve the respiratory health of Indigenous infants in Australia and New Zealand. Qualitative semi-structured interviews were conducted with 26 Indigenous mothers of infants in Australia (n=7) and NZ (n=19). We asked about the presence of smokefree rules, who set the rules, how the rules were set and enforced, and presence of smokefree rules in participants' wider social circle. Interviews were audiotaped, transcribed, and inductively analysed to identify key themes.

FINDINGS

Sixty-nine percent of mothers had partners, 77% smoked and all reported some presence of smokefree rules for house and car. Three main themes were identified: strategies to minimise exposure to ETS, establishing smokefree rules in homes and cars, and, adherence and enforcement of smokefree rules. Several strategies were identified to limit children's exposure to ETS, including rules to limit exposure to third-hand smoke. Mothers extended their smokefree rules to apply to other people's houses or cars, and reported that their family and social circles also had smokefree rules. The main reason for having smokefree rules was for the health of their children. Rules were most commonly set by the mother, often jointly with their partner. Few mothers reported challenges or problems with other people adhering to the smokefree rules.

CONCLUSION

Women tried very hard to, and believed that they were effective in, protecting their children from the harmful effects of ETS exposure. In this context, health professionals need to emphasise smoking cessation in parents, so that children are maximally protected from ETS exposure.

It is time to regulate carcinogenic tobacco-specific nitrosamines in cigarette tobacco

The Family Smoking Prevention and Tobacco Control Act gives the U.S. Food and Drug Administration power to regulate tobacco products. This commentary calls for immediate regulation of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) in cigarette tobacco as a logical path to cancer prevention. NNK and NNN, powerful carcinogens in laboratory animals, have been evaluated as "carcinogenic to humans" by the International Agency for Research on Cancer. NNK and NNN are present in the tobacco of virtually all marketed cigarettes; levels in cigarette smoke are directly proportional to the amounts in tobacco. The NNK metabolite NNAL, itself a strong carcinogen, is present in the urine of smokers and nonsmokers exposed to secondhand smoke. Some of the highest levels of NNK and NNN are found in U.S. products. It is well established that factors such as choice of tobacco blend, agricultural conditions, and processing methods influence levels of NNK and NNN in cigarette tobacco and cigarette smoke. Therefore, it is time to control these factors and produce cigarettes with 100 ppb or less each of NNK and NNN in tobacco, which would result in an approximate 15- to 20-fold reduction of these carcinogens in the mainstream smoke of popular cigarettes sold in the United States.

Children's exposure to secondhand and thirdhand smoke carcinogens and toxicants in homes of hookah smokers

INTRODUCTION

We examined homes of hookah-only smokers and nonsmokers for levels of indoor air nicotine (a marker of secondhand smoke) and indoor surface nicotine (a marker of thirdhand smoke), child uptake of nicotine, the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and the toxicant acrolein by analyzing their corresponding metabolites cotinine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and NNAL-glucuronides (total NNAL) and 3-hydroxypropylmercapturic acid.

METHODS

Data were collected at 3 home visits during a 7-day study period from a convenience sample of 24 households with a child 5 years or younger. Three child urine samples and 2 air and surface samples from the living room and the child bedroom were taken in homes of nonsmokers (n = 5) and hookah-only smokers (n = 19) comprised of daily hookah smokers (n = 8) and weekly/monthly hookah smokers (n = 11).

RESULTS

Nicotine levels in indoor air and on surfaces in the child bedrooms in homes of daily hookah smokers were significantly higher than in homes of nonsmokers. Uptake of nicotine, NNK, and acrolein in children living in daily hookah smoker homes was significantly higher than in children living in nonsmoker homes. Uptake of nicotine and NNK in children living in weekly/monthly hookah smoker homes was significantly higher than in children living in nonsmoker homes.

CONCLUSIONS

Our data provide the first evidence for uptake of nicotine, the tobacco-specific lung carcinogen NNK, and the ciliatoxic and cardiotoxic agent acrolein in children living in homes of hookah smokers. Our findings suggest that daily and occasional hookah use in homes present a serious, emerging threat to children's long-term health.

Thirdhand tobacco smoke: a tobacco-specific lung carcinogen on surfaces in smokers' homes

INTRODUCTION

Thirdhand tobacco smoke consists of substances remaining on the surfaces or in the dust of areas where people have smoked. While previous studies have demonstrated the presence of nicotine and various other constituents of tobacco smoke on surfaces in smokers' homes, none has investigated the presence of tobacco-specific carcinogens.

METHODS

We used liquid chromatography-tandem mass spectrometry to analyze surface dust samples from both the homes of smokers and nonsmokers for the powerful tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).

RESULTS

We positively identified NNK on surfaces in 33 of 37 smokers' homes (700±788 pg/100cm(2) [range, not detected-3,500 pg/100cm(2)]), but only in 3 of 19 nonsmokers' homes (235±176 pg/100cm(2) in the homes where NNK was detected [range, not detected-435 pg/100cm(2)]). The differences in occurrence and levels of NNK in the homes of smokers and nonsmokers were significant (p < .0001).

CONCLUSIONS

The powerful tobacco-specific lung carcinogen NNK is present on surfaces in most homes occupied by smokers. Potential renters or buyers of apartments or homes should be notified if previous residents were smokers in order to avoid unnecessary exposure of their families to a potent lung carcinogen.

Lung cancer in never smokers: disease characteristics and risk factors

It is estimated that approximately 25% of all lung cancer cases are observed in never-smokers and its incidence is expected to increase due to smoking prevention programs. Risk factors for the development of lung cancer described include second-hand smoking, radon exposure, occupational exposure to carcinogens and to cooking oil fumes and indoor coal burning. Other factors reported are infections (HPV and Mycobacterium tuberculosis), hormonal and diatery factors and diabetes mellitus. Having an affected relative also increases the risk for lung cancer while recent studies have identified several single nucleotide polymorphisms associated with increased risk for lung cancer development in never smokers. Distinct clinical, pathology and molecular characteristics are observed in lung cancer in never smokers; more frequently is observed in females and adenocarcinoma is the predominant histology while it has a different pattern of molecular alterations. The purpose of this review is to summarize our current knowledge of this disease.

Protecting the world from secondhand tobacco smoke exposure: where do we stand and where do we go from here?

INTRODUCTION

Article 8 of the Framework Convention on Tobacco Control mandates all signatory countries to "protect citizens from exposure to tobacco smoke in workplaces, public transport and indoor public places." Even though there has been great progress in the implementation of Article 8, still most of the world population remains exposed to secondhand smoke (SHS). In this article, we sought to summarize the research that supports Article 8, where do we stand, and current research gaps and future directions.

DISCUSSION

Secondhand smoke is an established cause of heart disease and several types of cancer. Additional research is needed to reach final conclusions for diseases where evidence is only suggestive of causality. The only solution to SHS exposure in public places is banning smoking indoors. Research on the gaming industry and nightclubs, particularly in developing countries, needs to be disseminated to support their inclusion in smoke-free laws. Aside from indoor bans, additional research is needed for outdoor and multiunit housing bans and in support of measures that protect children and other vulnerable populations. The impact of smoke-free laws on other health outcomes, besides heart disease and respiratory outcomes, is another area where further research is needed. Thirdhand smoke assessment and health effects are also likely to be a topic of further research. As new tobacco products emerge, evaluating SHS exposure and effects will be vital.

CONCLUSIONS

Furthering research in support of Article 8 can contribute to reach the final goal of protecting everyone from SHS exposure.

Lung cancer in never smokers--a review

An estimated 10-25% of lung cancers worldwide occur in never smokers, i.e. individuals having smoked less than 100 cigarettes in their lifetime. Lung cancer in never smokers (LCINS) is more frequent in women, although large geographic variations are found. Histologically, adenocarcinomas predominate. The mere existence of LCINS suggests that risk factors other than smoking must be present. Exposure to environmental tobacco smoke (particularly in women) and exposure to workplace carcinogens (particularly in men) are the two most important alternative risk factors. However, a history of either is absent in more than a third of LCINS. The large proportion of women in LCINS suggest a hormonal element that may interact with other identified factors such as hereditary risks, a history of respiratory infections or disease, exposure to air pollution, cooking and heating fumes, or exposure to ionising radiation. The study of genomic polymorphisms finds constitutive DNA variations across subjects according to their smoking status, particularly in genes coding for enzymes that participate in the metabolism of certain carcinogens, in those coding for DNA repair enzymes, or in genes associated with tobacco addiction, or inflammatory processes. The type of molecular mutation in p53 or KRAS varies with smoking status. EGFR mutations are more frequent in never smokers, as are EML4-ALK fusions. The mutually exclusive nature of certain mutations is a strong argument in favour of separate genetic paths to cancer for ever smokers and never smokers. In the present paper we review current clinical and molecular aspects of LCINS.

Factors influencing exposure to secondhand smoke in preschool children living with smoking mothers

INTRODUCTION

The health effects on young children of exposure to secondhand smoke (SHS) are well described. Recent work suggests that over one quarter of school-aged children in Scotland are regularly exposed to SHS in the home. The study was designed to describe SHS exposure in preschool children whose mothers smoked and identify factors that influence exposure.

METHODS

Smoking mothers with at least one child aged 1-5 years were recruited to the Reducing Families' Exposure to Secondhand Smoke in the Home study. Concentrations of airborne particulate matter less than 2.5 μm in size (PM(2.5)) in the home were measured together with child's salivary cotinine. Demographics including age, accommodation type, socioeconomic status, and number of cigarettes smoked at home were recorded.

RESULTS

Data were collected from 54 homes. In 89% of the homes, concentrations of PM(2.5) exceeded health-based guidance values at some point of the day. Household PM(2.5) concentrations were highest during the evening hours of 6 p.m. to midnight. Younger children had higher salivary cotinine concentrations than older children, and the geometric mean of salivary cotinine was 2.36 ng/ml. Household smoking restrictions and maternal confidence in enforcing smoking restrictions in their own home were strongly associated with child's SHS exposure.

CONCLUSIONS

Preschool children's exposure to SHS in homes where the mother smokes is considerable. Interventions and policy development to increase parental awareness of the health effects of SHS and provide parents with the confidence to implement smoke-free households are required to reduce the SHS exposure of preschool age children.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone is correlated with 8-hydroxy-2'-deoxyguanosine in humans after exposure to environmental tobacco smoke

Cigarette smoking and exposure to environmental tobacco smoke (ETS) are important risk factors for many cancers. However, exposure doses have usually not been quantitatively assessed in human studies. In humans 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronate conjugate (defined as total NNAL) are the major metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, a cigarette-specific carcinogen. Although animal studies have shown that exposure to cigarette smoke increases tissue oxidative DNA damage, the relationship between cigarette smoke and 8-hydroxydeoxyguanosine (8-OHdG) is not consistent in human studies. In the present study, we have developed a simple, sensitive, and robust LC-MS/MS method for quantifying total NNAL and 8-OHdG concentrations in human plasma. We quantified total NNAL and 8-OHdG in plasma as well as 8-OHdG in urine of 121 healthy male subjects. Total NNAL levels were significantly higher in ever-smokers than in never-smokers. Furthermore, total NNAL levels in plasma were increased with numbers of cigarettes smoked per day in ever-smokers. It suggests that total NNAL in plasma is a good biomarker for cigarette smoke exposure. After stratifying by smoking status and adjusting for age, ETS exposure and occupation category, total NNAL was associated with plasma and urinary 8-OHdG in never-smokers, but not in ever-smokers. Since total NNAL levels in nonsmokers represented the ETS exposure, it appears that 8-OHdG levels are dose-dependently correlated with their ETS exposure dose. Furthermore, this correlation supports the hypothesis that oxidative DNA damage is one of major adverse effects induced by ETS exposure in humans.

The ratio of a urinary tobacco-specific lung carcinogen metabolite to cotinine is significantly higher in passive than in active smokers

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol plus its glucuronides (total NNAL), metabolites of the lung carcinogen NNK, and total cotinine, metabolites of nicotine, are biomarkers of active and passive cigarette smoking. We calculated the total NNAL:total cotinine (×10(3)) ratio in 408 passive (infants, children, and adults) and 1088 active smokers. The weighted averages were 0.73 (95% confidence interval 0.71, 0.76) for passive smokers and 0.07 (0.06, 0.08) for active smokers (p < 0.0001). These results demonstrate that cotinine measurements may underestimate exposure of passive smokers to the lung carcinogen NNK in second-hand cigarette smoke. The total NNAL:total cotinine (×10(3)) ratio may provide an improved biomarker for evaluating the health effects of passive smoking.