Differential exposure biomarker levels among cigarette smokers and smokeless tobacco consumers in the National Health and Nutrition Examination Survey 1999-2008.

Assessment of biomarkers is an appropriate way to estimate exposure to cigarette mainstream smoke and smokeless tobacco (SLT) constituents in tobacco consumers. Using the US National Health and Nutrition Examination Survey (NHANES, 1999-2008), biomarkers of volatile organic compounds, halogenated aromatic hydrocarbons (HAHs), polycyclic aromatic hydrocarbons (PAHs), acrylamide, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and metals were evaluated. In general, biomarker levels in SLT consumers were significantly lower than in smokers (excluding NNK and some HAHs) and were not significantly different compared with nonconsumers (excluding NNK and some PAHs). These results provide useful information for science-based risk assessment and regulation of tobacco products.

Evaluating oral noncombustible potential-reduced exposure products for smokers.

INTRODUCTION: Potential-reduced exposure products (PREPs) are marketed as a way for smokers to continue using tobacco while possibly lessening their tobacco toxicant intake. Some tobacco-based PREPs are combustible and intended to be smoked, while others are noncombustible and intended to be administered orally (e.g., Camel Snus [CS] tobacco sachets and Ariva tobacco tablets). The ability of these noncombustible PREPs to reduce smokers' exposure to cigarette-delivered toxicants and suppress tobacco abstinence symptoms effectively is unclear. Clinical laboratory methods have been used to measure combustible PREP-associated toxicant exposure and abstinence symptom suppression and could be applied to evaluating the effects of orally administered noncombustible PREPs. METHODS: In this study, 21 smokers (6 women) participated in four 5-day conditions that differed by product used: CS, Ariva, own brand cigarettes, or no tobacco. Measures included expired-air carbon monoxide (CO), the urinary metabolite of nicotine (cotinine), the urinary metabolite of the carcinogen NNK (NNAL-T), and subjective effect ratings. RESULTS: Relative to own brand, all other conditions were associated with CO and cotinine levels that were lower and abstinence symptom ratings that were greater. Only no-tobacco use was associated with significantly lower NNAL levels. Acceptability ratings were also lower in all conditions relative to own brand. DISCUSSION: Although these oral products reduce exposure to CO, their ineffective abstinence symptom suppression and low acceptability may limit their viability as PREPs. As with combustible PREPs, clinical laboratory study of orally administered noncombustible PREPs will be a valuable part of any comprehensive PREP evaluation strategy.

Quantitation of metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone after cessation of smokeless tobacco use.

Two major metabolites of the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were previously shown to be highly persistent in human urine after cessation of cigarette smoking. We hypothesized that NNK or its metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), was sequestered in the lung. In this study, we further evaluated this hypothesis by quantifying the NNK metabolites, NNAL and its glucuronides (NNAL-Gluc), in urine and plasma after cessation of smokeless tobacco use, in which NNK is administered p.o. rather than by inhalation. Thirteen male nonsmokers, 11 snuff dippers and 2 tobacco chewers, participated in the study. Urine and plasma were obtained at baseline and at intervals 2-126 days after cessation of smokeless tobacco use. The distribution half-lives t(1/2alpha) (days) of NNAL (1.32 +/- 0.85 versus 3.35 +/- 1.86) and NNAL-Gluc (1.53 +/- 1.22 versus 3.89 +/- 2.43) were significantly shorter in smokeless tobacco users than in smokers. There were no significant differences in the terminal half-lives t(1/2beta) (days) of NNAL (26.3 +/- 16.7 versus 45.2 +/- 26.9) and NNAL-Gluc (26.1 +/- 15.1 versus 39.6 +/- 26.0) in smokeless tobacco users and smokers. Baseline levels as well as renal clearance of the NNK metabolites correlated with number of tins or pouches of smokeless tobacco consumed. Ratios of (S)-NNAL:(R)-NNAL and (S)-NNAL-Gluc:(R)-NNAL-Gluc in urine were significantly (3.1-5.7 times) higher 7 days after cessation than at baseline in both smokeless tobacco users and smokers, indicating stereoselective retention of (S)-NNAL. Collectively, the results of this study suggest that there is a receptor in the human body, possibly in the lung, for (S)-NNAL, the more carcinogenic NNAL enantiomer. These data may have considerable implications for understanding mechanisms of tumor induction by NNK.

Tobacco-specific nitrosamines and their pyridine-N-glucuronides in the urine of smokers and smokeless tobacco users.

Tobacco-specific nitrosamines are believed to play a significant role as causes of cancer in people who use tobacco products. Whereas the uptake of one tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, has been shown by analysis of its metabolites in urine, there are no published studies on urinary levels of N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), and N'-nitrosoanabasine (NAB) or their metabolites in human urine. We developed a method for quantitation of NNN, NAT, NAB, and their pyridine-N-glucuronides NNN-N-Gluc, NAT-N-Gluc, and NAB-N-Gluc in human urine. Total NNN (NNN plus NNN-N-Gluc) was assayed using 5-methyl-N'-nitrosonornicotine as internal standard. Urine was treated with beta-glucuronidase. Following solvent partitioning and solid-phase extraction, total NNN was determined using gas chromatography with nitrosamine-selective detection. Total NAT and total NAB were quantified in the same samples. Separate quantitation of NNN and NNN-N-Gluc was accomplished by extraction of the urine with ethyl acetate before beta-glucuronidase hydrolysis; NNN was analyzed in the ethyl acetate extract, and after enzyme treatment, NNN released from NNN-N-Gluc was quantified in the extracted urine. Separate analyses of NAT, NAT-N-Gluc, NAB, and NAB-N-Gluc proceeded similarly. Analyte identities were confirmed by gas chromatography-tandem mass spectrometry. Mean levels of total NNN, NAT, and NAB in the urine of 14 smokers were (pmol/mg creatinine) 0.18 +/- 0.22, 0.19 +/- 0.20, and 0.040 +/- 0.039, respectively, whereas the corresponding amounts in the urine of 11 smokeless tobacco users were 0.64 +/- 0.44, 1.43 +/- 1.10, and 0.23 +/- 0.19, respectively. Pyridine-N-glucuronides accounted for 59% to 90% of total NNN, NAT, and NAB. The results of this study show the presence of NNN, NAT, NAB, and their pyridine-N-glucuronides in human urine and provide a quantitative method for application in mechanistic and epidemiologic studies of the role of tobacco-specific nitrosamines in human cancer.

Metabolites of a tobacco-specific nitrosamine, 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone (NNK), in the urine of smokeless tobacco users: relationship between urinary biomarkers and oral leukoplakia.

Two metabolites of the carcinogenic tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone were quantified in the urine of smokeless tobacco users. The metabolites are 4-(methylnitrosamino) -1-(3-pyridyl)-1-butanol (NNAL) and [4-(methylnitrosamino)-1-(3-pyridyl) but-1-yl]-beta-O-D-glucosiduronic acid (NNAL-Gluc). The study population consisted of 47 male nonsmokers, of whom 23 were snuff dippers, 13 were tobacco chewers, 3 were users of both products, and 8 were nonusers. The levels of NNAL-Gluc in urine ranged from 0.14-30.3 pmol/mg creatinine with a mean +/- SD of 3.47 +/- 5.86, whereas the levels of NNAL ranged from 0.02-8.73 pmol/mg creatinine with a mean +/- SD of 0.92 +/- 1.59. The mean levels of NNAL-Gluc and NNAL were not significantly different from those measured in a previous study of smokers. The levels of NNAL-Gluc were significantly higher in snuff dippers than in tobacco chewers. The ratio of NNAL-Gluc:NNAL was higher in snuff dippers than in tobacco chewers or smokers. There was no indication of two phenotypes of the NNAL-Gluc:NNAL ratio in smokeless tobacco users, in contrast to previous observations in smokers. Of the 39 smokeless tobacco users in this study, 16 presented with oral leukoplakia. When the total levels of NNAL-Gluc, NNAL, or NNAL-Gluc + NNAL were divided into tertiles, there was a significant association between the presence of leukoplakia and increasing levels of these metabolites; a similar relationship was found between urinary cotinine and leukoplakia. The results of this study demonstrate that there is significant uptake of carcinogenic nitrosamines in smokeless tobacco users, and that such products are not harmless alternatives to cigarettes. Moreover, the urinary biomarkers NNAL-Gluc, NNAL, and cotinine were associated with the presence of leukoplakia, which provides biochemical support for the role of smokeless tobacco products as a cause of oral leukoplakia.

Expression of keratin 13, 14 and 19 in oral squamous cell carcinomas from Sudanese snuff dippers: lack of association with human papillomavirus infection.

In stratified squamous epithelia, altered expression of keratins (Ks) is one possible marker of malignant potential. In the epithelium of the uterine cervix, presence of human papillomaviruses (HPVs) is increasingly regarded as a marker of risk for cervical cancer. However, a similar role in oral cancer and precancer remains controversial. To address these questions, formalin-fixed, paraffin-embedded oral carcinomas from Sudanese snuff dippers (n=14) and oral carcinomas from Sudanese (n=14), Swedish (n=19) and Norwegian (n=41) non-snuff dippers were examined by immunohistochemistry for expression of K types 13, 14 and 19 using monoclonal antibodies. HPV infection was searched for in all the carcinomas by in situ hybridization (ISH) using the cocktail HPV OmniProbe and the ViraType probe. Carcinomas from Sudanese (snuff dippers/non-snuff dippers) were also examined for HPV infection by polymerase chain reaction (PCR) using the general HPV primers GP5+/GP6+. For the oral carcinomas from snuff dippers, moderate to intense expression of K13 (71%; 10/14), K14 (86%; 12/14) and K19 (93%; 13/14) was found. For the oral carcinomas from non-snuff dippers, weak to moderate expression of K13 (64%; 47/74), K14 (43%; 32/74) and K19 (45%; 33/74) was found. HPV DNA was not detected in any of the carcinomas from three countries when examined by ISH. The Sudanese (from snuff dippers/non-snuff dippers) oral carcinomas were also negative for HPV DNA with the PCR. The present study shows that (i) there is a high level of expression of K13, K14 and K19 in oral carcinomas from snuff dippers compared to those from non-snuff dippers, (ii) this high level of expression may arise from dysregulation of keratinocyte proliferation and maturation caused by damaging effects of snuff, (iii) the HPV genome is not found in Sudanese (snuff dippers/non-snuff dippers), Swedish or Norwegian oral carcinomas, and (iv) this may suggest that these viruses do not play a prominent role in the aetiology of oral carcinomas from these countries.

Forward mutation of S. typhimurium by smokeless tobacco extracts.

Mutagenicity of 4 popular brands of smokeless tobaccos was studied using a S. typhimurium forward mutation assay. Aqueous extracts of 4 brands and dichloromethane and methanol extracts of 1 of the 4 brands of smokeless tobacco's did not induce significant mutagenicity either in the presence or absence of metabolic activation. Aqueous and organic extracts were however mutagenic when treated with physiological levels of sodium nitrite (0.25 mM) at acidic pH and without metabolic activation. The results indicate that smokeless tobacco contain polar and non-polar chemicals which become mutagenic to S. typhimurium under nitrosation conditions.

Formation of bacterial mutagens from the reaction of chewing tobacco with nitrite.

Using the Salmonella/microsome assay system, the mutagenicity of chewing tobacco extracts (CTE) treated with and without sodium nitrite under acidic conditions was examined. Mutagenic activity was found only for nitrite-treated CTE in both tester strains, TA98 and TA100, and was independent of metabolic activation. Formation of mutagenic substances from CTE by nitrite was dependent on acidic pHs (the highest at pH 2) and could be inhibited by ascorbate. The mutagenic potency of CTE plus nitrite was proportional to the content of nitroso compounds generated in the reaction mixture, indicating that the nitrosation process was involved. The possible in vivo nitrosation and the potential health effect are discussed.

The relative buffering capacities of saliva and moist snuff: implications for nicotine absorption.

Commercial moist snuff products are used by placing a portion of tobacco inside the mouth between the inner cheek or lip and gum. Nicotine is absorbed into the blood stream via transfer across various oral membranes including the buccal mucosa (cheek lining). The resulting salivary pH when a given moist snuff product is placed in the mouth is an important factor for nicotine absorption because it will affect the proportion of free base nicotine that is readily available for absorption. The resulting salivary pH for a given moist snuff product will be determined in part by the relative acid-base buffering capacities of the saliva and moist snuff, as well as the pHs of the saliva and moist snuff prior to coming in contact with one another. In the current study, the acid-base buffering capacities (mu eq/g) of a series of commercial moist snuff products were determined and compared to the acid-base buffering capacity for unstimulated, whole human saliva. The buffering capacities of the moist snuff products were determined to be 10-20 times higher than the buffering capacity of human saliva. The resulting salivary pH ranges after contact between an artifical saliva and the various moist snuff products were also determined; the results were used to predict the proportion of free base nicotine that can be expected to occur in the mouth during the first few minutes of product use. These studies provide a basis for examining and understanding the effects that moist snuff product pHs and buffering capacities may be expected to have on nicotine absorption.

Urinary cotinine levels of smokeless tobacco (Maras powder) users.

Smokeless tobacco is used in various forms in some countries of the world. "Maras otu" is a kind of smokeless tobacco usage in the Southeastern region of Turkey. The use of smokeless tobacco causes nicotine addiction and dependence. Moreover this type of smokeless tobacco usage is one of the risk factors for oral cancers and genotoxic damages for users. Cotinine is widely used as a biomarker of tobacco consumption and intake of nicotine. Therefore, urine samples were collected from people who are using Maras powder and smoking cigarettes, and passive smokers, and the levels of cotinine investigated. The purpose of this study is to determine the cotinine levels of Maras powder users and to compare the results with cigarette smokers and passive smokers. Urinary cotinine levels of subjects were determined by using capillary gas chromatography with FID detection. The mean (+/- SD) urinary cotinines have been determined as 6467.35+/-3198 microg/g creatinine for 26 Maras powder users, 1943.92+/-1443 microg/g creatinine for 26 cigarette smokers and 198.62+/-420.82 microg/g creatinine for 26 passive smokers. A significant difference has been found between cotinine levels of Maras powder users and cigarette smokers, which is three times higher in Maras powder users (p<0.001). The present study suggests that smokeless tobacco poses a threat to public health and it should not be viewed as a safe alternative to cigarettes.

Lipid profile in smokers and tobacco chewers--a comparative study.

OBJECTIVE: The present study was undertaken to evaluate lipid profile in cigarette smokers and tobacco chewers and to see whether tobacco chewing causes same degree of alteration in lipid profile as done by smoking. METHODS: Serum lipid profile was studied in 30 smokers (Group A), 30 tobacco chewers (Group B) and 30 controls i.e., non-smokers and non-tobacco chewers (Group C). RESULTS: High density lipoprotein-cholesterol was lower both in smoker (P < 0.01) as well as in tobacco chewers (P < 0.001) than the controls. Both smokers and tobacco chewers had higher values of total cholesterol, low density lipoprotein cholesterol, very low density lipoprotein-cholesterol and, triglycerides as compared to non-smoker, non-tobacco chewer group whereas the differences in levels of lipids in smokers and tobacco chewers were not statistically significant. CONCLUSION: Though different mode of addictions, smoking and tobacco chewing have an equal and comparable adverse effects on lipid profile and therefore raising cardiovascular risk in same proportion.

Biochemical changes of saliva in tobacco chewers tobacco smokers, alcohol consumers, leukoplakia and oral cancer patients.

Normal salivary function is considered to be critical for the maintenance of healthy oral mucosa. Oral fluids provide an easily available non-invasive for the diagnosis of a wide range of diseases and clinical situations. The present study evaluated the variations in the biochemical constituents of saliva of leukoplakia and oral cancer patients when compared with that of the control group. 90 individuals were grouped into 6 categories with 15 individuals in each group. The groups included individuals without tobacco or alcohol habits, tobacco smokers, tobacco chewers, alcohol consumers, leukoplakia and oral cancer patients. There was significant alteration in the salivary biochemical composition of leukoplakia and oral cancer patients which could be attributed to the impairment of salivary gland function caused by tobacco and alcohol usage or by the disease process itself.

Exposure to nicotine and carcinogens among Southwestern Alaskan Native cigarette smokers and smokeless tobacco users.

BACKGROUND: The prevalence of tobacco use, both cigarette smoking and smokeless, including iqmik (homemade smokeless tobacco prepared with dried tobacco leaves mixed with alkaline ash), and of tobacco-related cancer is high in Alaskan Native people (AN). To investigate possible mechanisms of increased cancer risk we studied levels of nicotine and tobacco-specific nitrosamines (TSNA) in tobacco products and biomarkers of tobacco toxicant exposure in Southwestern AN people. METHODS: Participants included 163 cigarette smokers, 76 commercial smokeless tobacco, 20 iqmik, 31 dual cigarette smokers and smokeless tobacco, and 110 nontobacco users. Tobacco use history, samples of tobacco products used, and blood and urine samples were collected. RESULTS: Nicotine concentrations were highest in cigarette tobacco and TSNAs highest in commercial smokeless tobacco products. The AN participants smoked on average 7.8 cigarettes per day. Nicotine exposure, assessed by several biomarker measures, was highest in iqmik users, and similar in smokeless tobacco and cigarette smokers. TSNA exposure was highest in smokeless tobacco users, and polycyclic aromatic hydrocarbon exposure was highest in cigarette smokers. CONCLUSIONS: Despite smoking fewer cigarettes per day, AN cigarette smokers had similar daily intake of nicotine compared to the general U.S. population. Nicotine exposure was greatest from iqmik, likely related to its high pH due to preparation with ash, suggesting high addiction potential compared to other smokeless tobacco products. TSNA exposure was much higher with smokeless tobacco than other product use, possibly contributing to the high rates of oral cancer. IMPACT: Our data contribute to an understanding of the high addiction risk of iqmik use and of the cancer-causing potential of various forms of tobacco use among AN people.

A biorelevant in vitro release/permeation system for oral transmucosal dosage forms.

This research describes the development and validation of a biorelevant in vitro release/permeation system to predict the in vivo performance of oral transmucosal dosage forms. The system is a biorelevant bidirectional transmucosal apparatus which allows better simulation of oral cavity physiological variables in comparison to compendial dissolution apparatuses and therefore may be a better predictor of in vivo behavior. The feasibility of the bidirectional apparatus was studied using smokeless tobacco (snus) as a model oral transmucosal product. In this research, nicotine release and permeation was investigated from commercially available snus using a modified USP IV flow-through apparatus, a commercially available vertical diffusion cell and a fabricated novel bidirectional transmucosal apparatus. The percent nicotine released/permeated was utilized as an input function for the prediction of in vivo plasma nicotine profiles by back calculation based on the Wagner-Nelson method. The prediction errors in C(max) and AUC(0-∞) with the USP IV flow-through device, vertical diffusion cell and novel apparatus were 4.03, 22.85 and 1.59 and -5.85, 5.85 and -9.27% respectively. This work demonstrated the suitability of the novel bidirectional transmucosal apparatus for predicting the in vivo behavior of oral transmucosal products.

Acute effects of tobacco chewing on the systemic, pulmonary and coronary circulation.

BACKGROUND: Tobacco use is highly prevalent in India, with almost half of adult men consuming tobacco in either smoke or smokeless forms (particularly chewing). Although cigarette smoking is known to produce acute hemodynamic effects, there is a lack of data concerning such effects of chewing tobacco. OBJECTIVE: The aim of this study was to determine the acute hemodynamic and coronary vasomotor effects of chewing tobacco. METHODS: Twelve habitual tobacco chewers (mean ± SD age 51.3 ± 6.9 years) undergoing elective coronary angiography were included in the study. Following coronary angiography, a 7F thermodilution Swan Ganz continuous cardiac output pulmonary artery catheter was used to continuously measure the right heart pressures and cardiac output. Having obtained baseline hemodynamic data, 1g of tobacco was given to be chewed. Subsequently, hemodynamic data were obtained periodically over a period of 60 minutes. A repeat left coronary injection was performed, 10 minutes after giving the tobacco, in the right anterior oblique view to estimate the diameter of the left anterior descending (LAD) artery by quantitative coronary angiography. RESULTS: Chewing tobacco led to a significant acute increase in heart rate (from 68.3 ± 12.4 beats/min to 80.6 ± 14.6 beats/min, peaking at 10 minutes) and cardiac output (from 3.8 ± 0.45 L/min to 4.7 ± 0.64 L/min, peaking at 15 minutes). There were no significant changes in the right atrial, pulmonary artery, or wedge pressures and hence no change in the pulmonary vascular resistance. More importantly, chewing tobacco was associated with coronary vasoconstriction (proximal LAD diameter change from 3.17 ± 0.43 mm to 2.79 ± 0.37 mm; p-value 0.02; mid LAD diameter change from 2.75 ± 0.36 mm to 2.40 ± 0.22 mm; p-value 0.03). CONCLUSION: Chewing smokeless tobacco leads to coronary vasoconstriction and also produces significant hemodynamic alterations. These changes may have a bearing on excess vascular disease.

Determination of nicotine and nicotine metabolites in urine by hydrophilic interaction chromatography-tandem mass spectrometry: Potential use of smokeless tobacco products by ice hockey players.

Consumption of nicotine in the form of smokeless tobacco (snus, snuff, chewing tobacco) or nicotine-containing medication (gum, patch) may benefit sport practice. Indeed, use of snus seems to be a growing trend and investigating nicotine consumption amongst professional athletes is of major interest to sport authorities. Thus, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the detection and quantification of nicotine and its principal metabolites cotinine, trans-3-hydroxycotinine, nicotine-N'-oxide and cotinine-N-oxide in urine was developed. Sample preparation was performed by liquid-liquid extraction followed by hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS) operated in electrospray positive ionization (ESI) mode with selective reaction monitoring (SRM) data acquisition. The method was validated and calibration curves were linear over the selected concentration ranges of 10-10,000 ng/mL for nicotine, cotinine, trans-3-hydroxycotinine and 10-5000 ng/mL for nicotine-N'-oxide and cotinine-N-oxide, with calculated coefficients of determination (R(2)) greater than 0.95. The total extraction efficiency (%) was concentration dependent and ranged between 70.4 and 100.4%. The lower limit of quantification (LLOQ) for all analytes was 10 ng/mL. Repeatability and intermediate precision were ≤9.4 and ≤9.9%, respectively. In order to measure the prevalence of nicotine exposure during the 2009 Ice Hockey World Championships, 72 samples were collected and analyzed after the minimum of 3 months storage period and complete removal of identification means as required by the 2009 International Standards for Laboratories (ISL). Nicotine and/or metabolites were detected in every urine sample, while concentration measurements indicated an exposure within the last 3 days for eight specimens out of ten. Concentrations of nicotine, cotinine, trans-3-hydroxycotinine, nicotine-N'-oxide and cotinine-N-oxide were found to range between 11 and 19,750, 13 and 10,475, 10 and 8217, 11 and 3396, and 13 and 1640 ng/mL, respectively. When proposing conservative concentration limits for nicotine consumption prior and/or during the games (50 ng/mL for nicotine, cotinine and trans-3-hydroxycotinine and 25 ng/mL for nicotine-N'-oxide and cotinine-N-oxide), about half of the hockey players were qualified as consumers. These findings significantly support the likelihood of extensive smokeless nicotine consumption. However, since such conclusions can only be hypothesized, the potential use of smokeless tobacco as a doping agent in ice hockey requires further investigation.

Presence of the carcinogen N'-nitrosonornicotine in the urine of some users of oral nicotine replacement therapy products.

N'-nitrosonornicotine (NNN) is a strong carcinogen present in unburned tobacco and cigarette smoke. We here analyze data obtained in two studies, in which a biomarker of exposure to NNN--the sum of NNN and its pyridine-N-glucuronide, called total NNN--was quantified in the urine of people who had stopped smoking and used various nicotine replacement therapy (NRT) products. In 13 of 34 nicotine gum or lozenge users from both studies, total NNN at one or more time points after biochemically confirmed smoking cessation was comparable with, or considerably higher than, the baseline levels. For most of the subjects who used the nicotine patch as a smoking cessation aid, urinary total NNN at all post-quit time points was <37% of their mean baseline levels. These results indicate that endogenous formation of significant amounts of NNN may occur sporadically in some users of oral NRT. Given the carcinogenicity of NNN and the frequent use of nicotine gum as a smoking cessation aid, further studies are needed so that preventive measures can be developed.

Evidence for endogenous formation of N'-nitrosonornicotine in some long-term nicotine patch users.

INTRODUCTION: Nitrosation of nicotine or its metabolites in the human body could lead to formation of the 2 carcinogenic tobacco-specific nitrosamines-N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). METHODS: We investigated the possibility of endogenous formation of NNN in people who had stopped smoking and used the 21-mg nicotine patch for 6 months. We quantified urinary biomarkers of exposure to NNN-the sum of NNN and its pyridine-N-glucuronide, referred to as total NNN. Also measured were NNK metabolites-the sum of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its N- and O-glucuronides, referred to as total NNAL. RESULTS: The average decline of urinary total NNN was less drastic than that of total NNAL: 22% of baseline total NNN and 7.3% of baseline total NNAL were detected in urine 24 weeks after smoking cessation and patch use (p = .02). The average ratio of total NNN to total NNAL in the same urine samples increased from 0.14 in baseline urine to 0.38 after 24 weeks of nicotine patch use. DISCUSSION: Overall, these results demonstrate that endogenous formation of NNN may occur in nicotine patch users. However, the levels of urinary total NNN during patch use were generally extremely low. Moreover, in 10 of 20 subjects analyzed here, the rate of decline in total NNN was similar to that in total NNAL, indicating that endogenous formation of NNN is virtually nonexistent in these subjects. Supplementation with ascorbic acid could be a simple approach to block possible NNN formation in nicotine patch users.

Potential reduced exposure products (PREPs) for smokeless tobacco users: clinical evaluation methodology.

Several potential reduced exposure products (PREPs) for smokeless tobacco (SLT) users are marketed in the United States, though their effects are largely unknown. These products include some that are low in tobacco-specific nitrosamines (TSNs), like Stonewall, a pressed tobacco tablet, and General snus, a moist snuff product produced in Sweden. Methodology assessing the toxicant exposure and effects of cigarette-like PREPs for smokers has been developed, and might be modified for use in evaluating PREPs for SLT users. This report describes two studies examining the toxicant exposure and effects of two PREPs for SLT users. Study 1 (n = 13) consisted of four 4.5-hr laboratory sessions where SLT products (own brand, Stonewall, General snus, and tobacco-free placebo) were used for four 30-min episodes and nicotine exposure and tobacco/nicotine abstinence symptoms were measured. Study 2 (n = 19) consisted of four 5-day ad libitum use periods when participants used own brand, Stonewall, General snus, or no SLT and urinary levels of metabolites of nicotine (cotinine) and the TSN 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNAL) and abstinence symptoms were measured. Compared with own brand, Stonewall was associated with lower levels of cotinine and NNAL, while General snus was associated with similar levels of cotinine and lower levels of NNAL. Abstinence symptoms generally did not differ across tobacco conditions. These results show that clinical laboratory methods can be used to evaluate the toxicant exposure and abstinence symptom suppression associated with PREPs for SLT users.