Biomonitoring of environmental tobacco smoke (ETS)-related exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)

Assessment of passive human exposure to tobacco smoke by environmental and biological monitoring in different public places in Wuhan, central China

Passive exposure to tobacco smoke is a global public health problem, while there are few data on public place monitoring and general population exposure assessment in central China. This study aimed to examine the levels of airborne nicotine (n = 256) in ten kinds of different public places in Wuhan, central China, and assess short-term and long-term smoke exposure in 340 non-smokers aged 18-67 who worked in these public places using tobacco biomarkers [i.e., cotinine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), respectively]. The highest median concentration of airborne nicotine (17.0 μg/m³) was observed in internet cafes, approximately 304-fold of the lowest value found in nurseries (55.9 ng/m³). Among the other studied public places, restaurants had the highest median concentrations (ng/m³) of airborne nicotine (3,120), followed by subway stations (810), hotels (624), government officess (286), middle schools (269), health institutions (268), public institutions (190), and primary schools (140). Urinary cotinine and NNAL were found in almost all the participants, and the highest concentrations were found in non-smokers from the internet cafes [specific gravity (SG)-corrected urinary median concentrations: 23.1 ng/mL, geometric mean (GM): 24.1 ng/mL, range: 0.62-1679 ng/mL] for cotinine and 104 pg/mL (GM: 97.6 pg/mL, range: 32.3-236 pg/mL) for NNAL, respectively]. Urinary cotinine concentrations in male non-smokers (median: 2.02 ng/mL) were significantly higher than those in female non-smokers (1.44) (P < 0.01). Participants aged 18-27 were detected with the highest urinary cotinine and NNAL concentrations. Urinary cotinine and NNAL concentrations were significantly correlated with daily and monthly working hours, respectively. Besides, a positive correlation was observed between log-transformed urinary concentrations of cotinine and NNAL (r = 0.32, P < 0.001). This is the first time to report matched data on airborne nicotine and urinary cotinine/NNAL among employees in different public places. This study demonstrated ubiquitous exposure to environmental tobacco smoke in the studied public places.

Assessment of the Exposure to NNN in the Plasma of Smokeless Tobacco Users

N-Nitrosonornicotine (NNN) is a human carcinogen present in cigarette smoke and smokeless tobacco. Urinary NNN is usually measured in order to assess the exposure to this toxicant for tobacco users. NNN excretion in urine can be highly biased due to the formation of NNN by nitrosation of nornicotine under acidic conditions, both endogenously and exogenously. Hence, urinary NNN levels may not necessarily correctly reflect the product-specific exposure. Measurement of plasma NNN may be less prone to endogenous formation due to the stable pH (7.4) of blood. We developed an LC-MS/MS method for the quantification of NNN using 1 mL of human plasma. Validation according to FDA guidelines proved that the method is selective and highly sensitive with an LLOQ of 0.3 pg/mL. Accuracy and precision averaged to 98.7 and 7.5% (CV), respectively. The assay was applied to plasma samples collected from 10 experienced moist smokeless tobacco users during and after a single use of 2 g of the product for 40 min under controlled use conditions. Blood was drawn at 15 time points over a 6 h time course. The maximum NNN concentration (Cmax) ranged from 3.5 to 10 pg/mL (mean: 7.1 pg/mL) at a tmax of 32 min. Plasma NNN and nicotine were found to have similar time courses. In conclusion, the determination of NNN in plasma may be fit-for-purpose to evaluate the product-use-specific exposure to this carcinogen.

A 90-day OECD TG 413 rat inhalation study with systems toxicology endpoints demonstrates reduced exposure effects of the aerosol from the carbon heated tobacco product version 1.2 (CHTP1.2) compared with cigarette smoke. I. Inhalation exposure, clinical pathology and histopathology

Within the framework of a systems toxicology approach, the inhalation toxicity of aerosol from a novel tobacco-heating potentially modified risk tobacco product (MRTP), the carbon-heated tobacco product (CHTP) 1.2, was characterized and compared with that of mainstream smoke (CS) from the 3R4F reference cigarette in a 90-day nose-only rat inhalation study in general accordance with OECD TG 413. CHTP1.2 is a heat-not-burn product using a carbon heat source to produce an aerosol that contains nicotine and tobacco flavor. At equal or twice the nicotine concentration in the test atmospheres, inhalation of CHTP1.2 aerosol led to a significantly lower exposure to harmful constituents and induced less respiratory tract irritation, systemic, and pathological effects compared with CS. Nasal epithelial changes were less pronounced in the CHTP1.2- than in the CS-exposed groups and reverted in the nicotine concentration-matched group after a recovery period. Lung inflammation was minimal in the CHTP1.2-treated groups compared with the moderate extent seen in the 3R4F groups. Many other toxicological endpoints evaluated did not show CHTP1.2 aerosol exposure-related effects, and no effects not seen for 3R4F were observed. These observations were consistent with findings from previous studies in which rats were exposed to MRTP aerosols containing similar nicotine concentrations.

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

There are established guidelines for bioanalytical assay validation and qualification of biomarkers. In this review, they were applied to a panel of urinary biomarkers of tobacco smoke exposure as part of a "fit for purpose" approach to the assessment of smoke constituents exposure in groups of tobacco product smokers. Clinical studies have allowed the identification of a group of tobacco exposure biomarkers demonstrating a good doseresponse relationship whilst others such as dihydroxybutyl mercapturic acid and 2-carboxy-1-methylethylmercapturic acid - did not reproducibly discriminate smokers and non-smokers. Furthermore, there are currently no agreed common reference standards to measure absolute concentrations and few inter-laboratory trials have been performed to establish consensus values for interim standards. Thus, we also discuss in this review additional requirements for the generation of robust data on urinary biomarkers, including toxicant metabolism and disposition, method validation and qualification for use in tobacco products comparison studies.

Selective determination of tobacco-specific nitrosamines in mainstream cigarette smoke by GC coupled to positive chemical ionization triple quadrupole MS

A rapid method for the selective determination of four kinds of tobacco-specific nitrosamines, N-nitrosonornicotine, N-nitrosoanatabine, N-nitrosoanabasine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, in mainstream cigarette smoke was developed by GC coupled to positive chemical ionization triple-quadrupole MS. After mainstream cigarette smoke was collected on a cambridge filter pad, the particulate matter was extracted with 0.1 M HCL aqueous solution, cleaned by positive cation-exchange solid extraction, and finally injected into GC-MS/MS using isotopically labeled analogues as internal standards. Excellent linearity was obtained over the concentration range of 0.5-200.0 ng mL(-1) for all tobacco-specific nitrosamines with values for correlation coefficient between 0.9996-0.9999. Limits of detection of each tobacco specific nitrosamine varied from 0.023-0.028 ng cig(-1), and lower limits of quantification varied from 0.077-0.093 ng cig(-1). The recovery of each tobacco specific nitrosamine was from 90.0-109.0%. The relative standard deviations of the intra-day and inter-day precisions were 3.1-5.8 and 3.9-6.6, respectively. This method was applied to reference and domestic cigarettes. The result showed that the method was consistent with traditional methods and can be used as an effective approach for the routine analysis of tobacco-specific nitrosamines.

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.

Rapid and sensitive gas chromatography-ion-trap tandem mass spectrometry method for the determination of tobacco-specific N-nitrosamines in secondhand smoke

Tobacco-specific nitrosamines (TSNAs) are some of the most potent carcinogens in tobacco and cigarette smoke. Accurate quantification of these chemicals is needed to help assess public health risks. We developed and validated a specific and sensitive method to measure four TSNAs adsorbed to model surfaces and secondhand smoke (SHS) particles using gas chromatography-ion-trap tandem mass spectrometry. In an 18-m(3) room-sized chamber, a smoking machine generated realistic concentrations of SHS that were actively sampled on Teflon-coated fiber glass (TCFG) filters, and passively sampled on cellulose substrates. A simple solid-liquid extraction protocol using methanol as solvent was successfully applied to both substrates with recoveries ranging from 85 to 115%. For each TSNA, tandem MS parameters were optimized and the major fragmentation pathways were elucidated. The method showed excellent performance, with a linear dynamic range from 2 to 1000ngmL(-1), low detection limits (S/N>3) of 30-300pgmL(-1) and precision with experimental errors below 10% for all compounds. Moreover, no interfering peaks were observed, indicating a high selectivity of MS/MS without the need for a sample clean-up step. This method provides a suitable analytical tool to detect and quantify traces of TSNA in indoor environments polluted with SHS.

Mass spectrometric analysis of 4-hydroxy-1-(3-pyridyl)-1-butanone-releasing DNA adducts in human lung

An improved analytical method was developed for the analysis of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts in lung samples of patients undergoing surgery for lung cancer. HPB-releasing adducts can be formed by metabolic activation of the tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine, and have been reported to play an important role in tobacco carcinogenesis. [2,2,3,3-D(4)]HPB (D(4)-HPB) was used as an internal standard, and HPB released by acid hydrolysis of DNA was determined by gas chromatography/mass spectrometry in the negative ion chemical ionisation mode. The method is sensitive with a limit of detection of 5.9 fmol HPB and a limit of quantification of 15.2 fmol HBP/mg DNA. The recovery of HPB was 82+/-17% and the background response was 10.1+/-1.8 fmol HPB/sample. The concentration of HPB-releasing lung DNA adducts was significantly higher (p<0.0001) in 21 self-reported smokers compared to in 11 self-reported nonsmokers (404+/-258 fmol versus 59+/-56 fmol HPB/mg DNA, respectively). HPB-releasing hemoglobin adduct concentrations were only marginally higher in a subset of 12 smokers compared to in 7 nonsmokers (63+/-53 fmol versus 42+/-34 fmol HPB/g hemoglobin; p=0.36). No correlation was found between HPB-releasing adducts in DNA and hemoglobin (p=0.074).

Urinary metabolites of a tobacco-specific lung carcinogen in nonsmoking hospitality workers

Exposure of nonsmokers to environmental tobacco smoke results in increased risk for cancer and other diseases. In spite of this finding, some restaurants and bars continue to permit smoking. This study examined the uptake of nicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent lung carcinogen, in nonsmokers who work in restaurants and bars that permitted smoking. Urine samples were collected for 24 hours on working and nonworking days and were analysed for total NNAL [the sum of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides (NNAL-Glucs)], metabolites of NNK. In addition, urine samples were analysed for total nicotine (nicotine plus nicotine glucuronide), and total cotinine (cotinine plus cotinine-N-glucuronide). The results showed significant increases in urinary levels of total NNAL, total nicotine, and total cotinine on working days compared with nonworking days. The results of this study show that smoke exposure in bars and restaurants may have important health effects on nonsmoking employees, elicited by the increase in carcinogen levels.

Biomonitoring of inhaled complex mixtures--ambient air, diesel exhaust and cigarette smoke

Human biomonitoring comprises the determination of biomarkers in body-fluids, cells and tissues. Biomarkers are generally assigned to one of three classes, namely, biomarkers of exposure, effect or susceptibility. Since biomarkers represent steps in an exposure-disease continuum, their application in epidemiological studies ('molecular epidemiology') shows promise. However, to be a predictor of disease, a biomarker has to be validated. Validation criteria for a biomarker include intrinsic qualities such as specificity, sensitivity, knowledge of background in the population, existence of dose-response relationships, degree of inter- and intra-individual variability, knowledge of the kinetics, confounding and modifying factors. In addition, properties of the sampling and analytical procedures are of relevance, including constraints and non-invasiveness of sampling, stability of sample as well as simplicity, high sensitivity, specificity and speed of the analytical method. It is of particular importance to prove by suitable studies that the biomarker of exposure indicates the actual exposure, the biomarker of effect strongly predicts the actual risk of disease and the biomarker of susceptibility actually modifies the risk. Biomonitoring of the exposure to complex mixtures such as polluted ambient air, diesel exhaust or tobacco smoke is a particular challenge since these exposures have many constituents in common and many people were exposed to more than one of these mixtures. Data on the exposure to polycyclic aromatic hydrocarbons (PAH) and benzene from ambient air, diesel exhaust and tobacco smoke will be presented. In addition, some source-specific biomarkers such as nitro-arenes and nicotine metabolites as well as their application in population groups will be discussed. The second part of the presentation addresses the application of biomarkers for assessing so called 'potentially reduced exposure products' (PREPs). According to a recent report of the Institute of Medicine (USA), "reducing risk of disease by reducing exposure to tobacco toxicants is feasible" and "surrogate biological markers that are associated with tobacco-related diseases could be used to offer guidance as to whether or not PREPs are likely to be risk-reducing." In general, the same validation criteria apply as discussed above. In addition, it is suggested that a panel of biomarkers should be used, representing both smoke phases (gas and particulate phase) and the various chemical classes of smoke constituents (e.g., carbonyls, benzene, PAH, tobacco-specific nitrosamines, aromatic amines). Also, a panel of biomarkers of effect should cover the major known adverse effects of smoking (e.g., oxidative stress, inflammatory processes, lipid peroxidation, lipometabolic disorders, mutagenic effects). Biomarkers of nicotine and carbon monoxide uptake are of interest for evaluating the smoking and inhalation behavior, respectively. Finally, suitable study designs for evaluating PREPs are discussed. It is concluded that suitable biomarkers for assessing the exposure to complex mixtures such as ambient air, diesel exhaust and tobacco smoke as well as for evaluating the exposure-reducing properties of PREPs are already available. Future efforts should focus on the development and validation of biomarkers of effect.

Effects of Cruciferous Vegetable Consumption on Urinary Metabolites of the Tobacco-Specific Lung Carcinogen 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone in Singapore Chinese

Vegetable consumption, including cruciferous vegetables, is protective against lung cancer, but the mechanisms are poorly understood. The purpose of this study was to investigate the effects of cruciferous vegetable consumption on the metabolism of the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in smokers. The study was carried out in Singapore Chinese, whose mean daily intake of cruciferous vegetables is three times greater than that of people in the United States. Eighty-four smokers provided urine samples and were interviewed about dietary habits using a structured questionnaire, which included questions on consumption of nine commonly consumed cruciferous vegetables. Samples of these vegetables obtained in Singapore markets at three different times of year were analyzed for glucosinolates. Urine was analyzed for metabolites of NNK: 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides (NNAL-Glucs). Glucobrassicins, which release indole-3-carbinols on chewing, were the major glucosinolates in seven of the nine cruciferous vegetables, accounting for 70.0% to 93.2% of all glucosinolates in these vegetables. There was a significant correlation (P = 0.01) between increased consumption of glucobrassicins and decreased levels of NNAL in urine after adjustment for number of cigarettes smoked per day; similar trends were observed for NNAL-Glucs (P = 0.08) and NNAL plus NNAL-Glucs (P = 0.03). These results are consistent with those of previous studies, which demonstrate that indole-3-carbinol decreases levels of urinary NNAL probably by inducing hepatic metabolism of NNK. The results are discussed with respect to the known chemopreventive activity of indole-3-carbinol against lung tumorigenesis by NNK in mice and the effects of isothiocyanates, which are also formed on consumption of cruciferous vegetables, on NNK metabolism. The results of this study demonstrate the complexities in assessing effects of cruciferous vegetables on carcinogen metabolism.

An international survey of indoor air quality, ventilation, and smoking activity in restaurants: a pilot study

During a pilot study of indoor air quality in restaurants, a survey was performed in 34 medium-priced restaurants in six countries in Asia, Europe, and North America using a uniform protocol. The concentration of selected constituents of environmental tobacco smoke (ETS) present in occupied areas was determined during lunch and dinner periods by measuring the levels of four particulate-phase markers and two gas-phase markers. The particulate-phase markers determined were respirable suspended particles, ultraviolet particulate matter, fluorescing particulate matter, and solanesol particulate matter. The gas-phase markers were nicotine and 3-ethenylpyridine (3-EP). Correlation between the markers was investigated to explore an improved monitoring approach. It was concluded that at least one marker in each phase was necessary to describe adequately the ETS load. An assessment was made of the ventilation system in each restaurant, and effective ventilation rates were determined based on CO(2) measurements. Smoking activity was also monitored. These data were used to model nicotine and 3-EP concentrations that resulted in a satisfactory prediction of their levels, especially at the higher concentrations. A total number of 1370 questionnaires were returned by the restaurant patrons in five countries. In some countries, dissatisfaction rates above 20% were observed for draft, freshness of air, and noise. The dissatisfaction rates related to tobacco smoke were less than 20%, which is lower than would be predicted based on measured ETS levels. Based on the results of this international pilot study, recommendations are given for future studies of this type.

Nitrosation of dietary myosmine as risk factor of human cancer

The tobacco alkaloid myosmine was detected in nut and nut products [J. Agric. Food Chem. 46 (1998) 2703]. Upon nitrosation, myosmine yields 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) and N-nitrosonornicotine (NNN) [J. Agric. Food Chem. 48 (2001) 392]. NNN is a strong oesophageal carcinogen in rats. Metabolic activation of NNN leads to formation of DNA and protein adducts which release HPB upon hydrolysis. In the present study the time, pH and dose-dependent nitrosation of myosmine and its covalent binding to DNA was investigated. [5-(3)H]myosmine was incubated with nitrite for 1-24 h in buffer solutions adjusted to pH 1-6. At pH 2-4 myosmine was easily nitrosated and gave rise to two major products, HPB and NNN, and five minor not yet identified products. Maximal formation was achieved for HPB at pH 2 after 8 h (72% of total radioactivity) and for NNN at pH 3 after 8 h (16%). For DNA binding studies labeled myosmine was incubated under nitrosation conditions with calf thymus DNA. Within 3 h up to 0.1% of the radioactivity was covalently bound to DNA. Endogenous nitrosation of myosmine, present in nuts and other dietary components could constitute a significant risk factor for tumours in the upper intestinal tract such as oesophageal adenocarcinoma, which are unrelated to tobacco smoking and alcohol abuse.

Human urinary carcinogen metabolites: biomarkers for investigating tobacco and cancer

Measurement of human urinary carcinogen metabolites is a practical approach for obtaining important information about tobacco and cancer. This review presents currently available methods and evaluates their utility. Carcinogens and their metabolites and related compounds that have been quantified in the urine of smokers or non-smokers exposed to environmental tobacco smoke (ETS) include trans,trans-muconic acid (tt-MA) and S-phenylmercapturic acid (metabolites of benzene), 1- and 2-naphthol, hydroxyphenanthrenes and phenanthrene dihydrodiols, 1-hydroxypyrene (1-HOP), metabolites of benzo[a]pyrene, aromatic amines and heterocyclic aromatic amines, N-nitrosoproline, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (NNAL and NNAL-Gluc), 8-oxodeoxyguanosine, thioethers, mercapturic acids, and alkyladenines. Nitrosamines and their metabolites have also been quantified in the urine of smokeless tobacco users. The utility of these assays to provide information about carcinogen dose, delineation of exposed vs. non-exposed individuals, and carcinogen metabolism in humans is discussed. NNAL and NNAL-Gluc are exceptionally useful biomarkers because they are derived from a carcinogen- 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)- that is specific to tobacco products. The NNAL assay has high sensitivity and specificity, which are particularly important for studies on ETS exposure. Other useful assays that have been widely applied involve quantitation of 1-HOP and tt-MA. Urinary carcinogen metabolite biomarkers will be critical components of future studies on tobacco and human cancer, particularly with respect to new tobacco products and strategies for harm reduction, the role of metabolic polymorphisms in cancer, and further evaluation of human carcinogen exposure from ETS.

Distribution analysis of airborne nicotine concentrations in hospitality facilities

A number of publications report statistical summaries for environmental tobacco smoke (ETS) concentrations. Despite compelling evidence for the data not being normally distributed, these publications typically report the arithmetic mean and standard deviation of the data, thereby losing important information related to the distribution of values contained in the original data. We were interested in the frequency distributions of reported nicotine concentrations in hospitality environments and subjected available data to distribution analyses. The distribution of experimental indoor airborne nicotine concentration data taken from hospitality facilities worldwide was fit to lognormal, Weibull, exponential, Pearson (Type V), logistic, and loglogistic distribution models. Comparison of goodness of fit (GOF) parameters and indications from the literature verified the selection of a lognormal distribution as the overall best model. When individual data were not reported in the literature, statistical summaries of results were used to model sets of lognormally distributed data that are intended to mimic the original data distribution. Grouping the data into various categories led to 31 frequency distributions that were further interpreted. The median values in nonsmoking environments are about half of the median values in smoking sections. When different continents are compared, Asian, European, and North American median values in restaurants are about a factor of three below levels encountered in other hospitality facilities. On a comparison of nicotine concentrations in North American smoking sections and nonsmoking sections, median values are about one-third of the European levels. The results obtained may be used to address issues related to exposure to ETS in the hospitality sector.