Levels Of Tobacco-specific Nitrosamines Research Articles

Carcinogen Exposure among Canadian Tobacco Users: Changes in NNK Exposure from 2007-2009 through 2012-2013.

Background: Tobacco-specific nitrosamines (TSNAs) are a class of carcinogens found in tobacco products, whose levels can vary considerably depending on tobacco blends and manufacturing processes. The current study examined whether recent increases in levels of the TSNA NNK [4-(methylnitrosamino-1-(3-pyridyl)-1-butanone] in Canadian cigarettes translated into differences in exposure among Canadian tobacco users.Methods: Nationally representative data from the Canadian Health Measures Survey (CHMS) were used to measure levels of total urinary NNAL [4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol], a metabolite of the TSNA NNK, among tobacco users. Data from CHMS Cycle 3 (2012-13) were used to examine NNAL, and linear regression was used to examine predictors. Data from CHMS Cycle 1 (2007-09) and Cycle 3 (2012-13) were used to examine changes in NNAL over time.Results: From 2007-2009 through 2012-2013, levels of creatinine-corrected NNAL increased by 64% (P < 0.0001). Levels of NNAL in 2012-2013 were higher among older respondents (P = 0.04), among females (P = 0.03), among respondents identifying as "white" and "Aboriginal" (P < 0.0001), and among those with greater daily cigarette consumption (P < 0.001), as well as greater levels of urinary free cotinine (P < 0.0001) and urinary creatinine (P < 0.0001).Conclusions: The findings indicate that exposure to the TSNA NNK among Canadian tobacco users has increased considerably from 2007-2009 through 2012-2013, in parallel to changes in TSNA levels in Canadian cigarettes. In the absence of epidemiologic data, it is unclear whether this change translates into increased risk.Impact: The study findings have potential implications for tobacco manufacturers, who bear a responsibility to reduce levels of tobacco carcinogens to the full extent possible. Cancer Epidemiol Biomarkers Prev; 27(3); 262-7. ©2018 AACR.

Trends Over Time in Tobacco-Specific Nitrosamines (TSNAs) in Whole Tobacco and Smoke Emissions From Cigarettes Sold in Canada.

Tobacco-specific nitrosamines (TSNAs) are potent carcinogens. Levels of TSNAs can be modified through manufacturing practices. In the 2000s, TSNA levels in cigarettes sold in Canada were reduced by changes in tobacco curing processes. The current study examined TSNA levels over the following decade to examine trends over time. Data submitted to Health Canada under the Tobacco Reporting Regulations were used to examine whole tobacco constituents for 1809 brands and mainstream smoke emissions for 191 brands manufactured by Canada's three leading cigarette companies from 2005 through 2011/12 using one-way analysis of variances (ANOVAs) and linear regression models. Levels of N-nitrosoanatabine (NAT) (p < .001) and 4-(methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) (p < .001) in whole tobacco showed significant differences over time, decreasing between 2005 and 2007, and generally increasing from 2007 through 2012. Levels of all TSNAs in mainstream smoke emissions reflected a similar pattern: N-nitrosoanabasine (NAB) (p < .001), NAT (p < .001), NNK (p < .001), and N'-nitrosonornicotine (NNN) (p = .021). Linear regression analyses showed that TSNA levels varied by manufacturer over time in whole tobacco for NAT, NNK, and NNN (p < .001 for all), and in smoke emissions for NAB, NAT, NNK, and NNN (p < .001 for all). The findings indicate that levels of TSNAs in whole tobacco and smoke emissions of cigarettes sold in Canada increased from 2007 through 2011/12, following initial reductions over the previous 2 years. Differences in TSNA levels between companies raise questions about manufacturing practices that may be responsible for these changes. Although increased levels of carcinogenic TSNAs may be alarming, it remains unclear whether these differences translate into differences in health risk. The wide variation of TSNAs within the Canadian market across time and across cigarette companies demonstrates the feasibility of reducing the levels of these potent carcinogens. Although it is unclear whether changes made to levels of TSNAs will result in less tobacco-related disease, the tobacco industry bears a responsibility to minimize the harm from smoking to the fullest extent possible.

Acetylsalicylic acid application decreased tobacco-specific nitrosamines and its precursors but maintained quality of air-cured burley tobacco (Nicotiana tabacum L.)

Burley tobacco (Nicotiana tabacum L.) is an important raw material in the production of Chinese-style blended cigarettes. However, the high levels of tobacco-specific nitrosamines (TSNA) have devalued the industrial use of burley tobacco and limited its sustainable use. The objective of this paper was to investigate the effects of acetylsalicylic acid (ASA) application on accumulation of TSNA, its precursors and quality of air-cured burley tobacco (Nicotiana tabacum L. cv. DaBai 1). Field experiments were conducted to determine the contents of TSNA and the precursors and the sensory quality of burley tobacco under 0, 0.1, 0.3mM of ASA in 2014 and 2015 at Dazhou, Sichuan Province, China. The results showed that TSNA, nitrate, nitrite and alkaloids levels were significantly reduced by the application of ASA, of which the total TSNA were significantly lower by 10.40–24.75%, and two of the strong animal carcinogens in tobacco products, i.e. N-nitrosonornicotine (NNN) and 4-(methylnitrosamino) -1- (3- pyridyl) -1- butanone (NNK) were reduced by 9.01–24.23% and 11.43–26.86%, respectively. Year had significant effects on TSNA and the TSNA contents in 2014 were higher than in 2015. Interestingly, the sensory quality of burley tobacco remained or was even better after application of ASA. In conclusion, this study revealed that ASA application was able to reduce the levels of TSNA and its precursors in sustaining burley tobacco industry potentially.

Analysis of Traces of Tobacco-Specific Nitrosamines (TSNAs) in USP Grade Nicotine, E-Liquids, and Particulate Phase Generated by the Electronic Smoking Devices

Summary The present study describes the development of a liquid chromatography tandem mass spectrometry (LC-MS/MS) technique for the analysis of trace levels of four tobaccospecific nitrosamines (TSNAs): nitrosoanabasine (NAB), nitrosoanatabine (NAT), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and nitrosonornicotine (NNN). The technique can be applied for the analysis of TSNAs in USP grade nicotine. Nicotine used in e-liquids for the electronic smoking devices is typically obtained from tobacco plant materials (Nicotiana tabacum, Nicotiana rustica) and, although it is purified, it contains besides nicotine low levels of several contaminants such as minor alkaloids. It also contains traces of TSNAs. Analysis of TSNAs in USP grade nicotine is a challenging task since the analyzed samples contain about 10+7–10+8 times more nicotine than individual TSNAs. Because the analyzed solutions cannot be diluted too much in order to keep the TSNAs level above the limit of quantitation (LOQ), even for apparently good chromatographic separations, the peak tailing of nicotine may generate interferences. The new method of analysis uses a Luna Omega 1.6 μm particles chromatographic column for separation and detection on a LC-MS/MS instrument with scheduled multiple reaction monitoring (Scheduled MRM). The levels of TSNAs in nicotine of USP purity from four commercial sources varied between 3 to 8 ng/g NAB, 4 to 20 ng/g NAT, 30 to 50 ng/g NNK, and 0.5 to 2 ng/g for NNN. Besides the analysis of TSNAs in nicotine, the technique has been applied successfully in the analysis of TSNAs in e-liquids and in particulate phase generated by the electronic smoking devices.

Tobacco-Specific Nitrosamines in the Tobacco and Mainstream Smoke of U.S. Commercial Cigarettes.

Tobacco-specific nitrosamines (TSNAs) are N-nitroso-derivatives of pyridine-alkaloids (e.g., nicotine) present in tobacco and cigarette smoke. Two TSNAs, N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are included on the Food and Drug Administration's list of harmful and potentially harmful constituents (HPHCs) in tobacco products and tobacco. The amounts of four TSNAs (NNK, NNN, N-nitrosoanabasine (NAB), and N'-nitrosoanatabine (NAT)) in the tobacco and mainstream smoke from 50 U.S. commercial cigarette brands were measured from November 15, 2011 to January 4, 2012 using a validated HPLC/MS/MS method. Smoke samples were generated using the International Organization of Standardization (ISO) and Canadian Intense (CI) machine-smoking regimens. NNN and NAT were the most abundant TSNAs in tobacco filler and smoke across all cigarette brands, whereas NNK and NAB were present in lesser amounts. The average ratios for each TSNA in mainstream smoke to filler content is 29% by the CI smoking regimen and 13% for the ISO machine-smoking regimen. The reliability of individual TSNAs to predict total TSNA amounts in the filler and smoke was examined. NNN, NAT, and NAB have a moderate to high correlation (R2 = 0.61-0.98, p < 0.0001), and all three TSNAs individually predict total TSNAs with minimal difference between measured and predicted total TSNA amounts (error < 7.4%). NNK has weaker correlation (R2 = 0.56-0.82; p < 0.0001) and is a less reliable predictor of total TSNA quantities. Tobacco weight and levels of TSNAs in filler influence TSNA levels in smoke from the CI machine-smoking regimen. In contrast, filter ventilation is a major determinant of levels of TSNAs in smoke by the ISO machine-smoking regimen. Comparative analysis demonstrates substantial variability in TSNA amounts in tobacco filler and mainstream smoke yields under ISO and CI machine-smoking regimens among U.S. commercial cigarette brands.

Blowing smoke: the history of tobacco-specific nitrosamines in Canadian tobacco

ObjectiveTo demonstrate how changes in tobacco flue-curing practices in the 20th century increased levels of tobacco-specific nitrosamines (TSNAs) in tobacco smoke.MethodsPreviously undisclosed documents and testimony made public as a result...

Analysis of Tobacco-Specific Nitrosamines in the Common Smokeless Tobacco Afzal in Oman.

There is a lack of awareness regarding the carcinogenicity of Afzal, an illegal smokeless tobacco product (STP) widely used among the Omani youth. Previous research has shown that certain types of tobacco-specific nitrosamines (TSNAs) are associated with oral and lung cancers. This study therefore aimed to assess levels of four common TSNAs in a randomly selected sample of Afzal. This study was carried out at Sultan Qaboos University in Muscat, Oman, between April and September 2013. A random sample of Afzal was analysed for four types of TSNAs using high-performance liquid chromatography-tandem mass spectrometry. The four types of TSNAs analysed were 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK), N-nitrosonornicotine (NNN), N-nitrosoanatabine (NAT) and N-nitrosoanabasine (NAB). As a reference product, a sample of laboratory-manufactured American moist snuff (Centers for Disease Control and Prevention, Atlanta, Georgia, USA) was also used to confirm the accuracy and precision of the analysis. The analysis revealed total TSNA levels of 3.573 μg/g in the Afzal sample. Mean levels of NNN, NNK, NAT and NAB were 1.205, 1.015, 0.809 and 0.545 μg/g, respectively. Levels of the two most abundant TSNAs (NNN and NNK) found in the Afzal sample exceeded international regulatory limits. Afzal users therefore need to be educated regarding the potential health risks associated with their STP use. Stricter implementation of current legislation is recommended to reduce the availability and usage of Afzal in Oman.

Expression of a constitutively active nitrate reductase variant in tobacco reduces tobacco-specific nitrosamine accumulation in cured leaves and cigarette smoke.

SummaryBurley tobaccos (Nicotiana tabacum) display a nitrogen‐use‐deficiency phenotype that is associated with the accumulation of high levels of nitrate within the leaf, a trait correlated with production of a class of compounds referred to as tobacco‐specific nitrosamines (TSNAs). Two TSNA species, 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK) and N‐nitrosonornicotine (NNN), have been shown to be strong carcinogens in numerous animal studies. We investigated the potential of molecular genetic strategies to lower nitrate levels in burley tobaccos by overexpressing genes encoding key enzymes of the nitrogen‐assimilation pathway. Of the various constructs tested, only the expression of a constitutively active nitrate reductase (NR) dramatically decreased free nitrate levels in the leaves. Field‐grown tobacco plants expressing this NR variant exhibited greatly reduced levels of TSNAs in both cured leaves and mainstream smoke of cigarettes made from these materials. Decreasing leaf nitrate levels via expression of a constitutively active NR enzyme represents an exceptionally promising means for reducing the production of NNN and NNK, two of the most well‐documented animal carcinogens found in tobacco products.

Fully automated analysis of four tobacco-specific N-nitrosamines in mainstream cigarette smoke using two-dimensional online solid phase extraction combined with liquid chromatography–tandem mass spectrometry

A fully automated method for the detection of four tobacco-specific nitrosamines (TSNAs) in mainstream cigarette smoke (MSS) has been developed. The new developed method is based on two-dimensional online solid-phase extraction–liquid chromatography–tandem mass spectrometry (SPE/LC–MS/MS). The two dimensional SPE was performed in the method utilizing two cartridges with different extraction mechanisms to cleanup disturbances of different polarity to minimize sample matrix effects on each analyte. Chromatographic separation was achieved using a UPLC C18 reversed phase analytical column. Under the optimum online SPE/LC–MS/MS conditions, N′-nitrosonornicotine (NNN), N′-nitrosoanatabine (NAT), N′-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were baseline separated with good peak shapes. This method appears to be the most sensitive method yet reported for determination of TSNAs in mainstream cigarette smoke. The limits of quantification for NNN, NNK, NAT and NAB reached the levels of 6.0, 1.0, 3.0 and 0.6pg/cig, respectively, which were well below the lowest levels of TSNAs in MSS of current commercial cigarettes. The accuracy of the measurement of four TSNAs was from 92.8 to 107.3%. The relative standard deviations of intra-and inter-day analysis were less than 5.4% and 7.5%, respectively. The main advantages of the method developed are fairly high sensitivity, selectivity and accuracy of results, minimum sample pre-treatment, full automation, and high throughput. As a part of the validation procedure, the developed method was applied to evaluate TSNAs yields for 27 top-selling commercial cigarettes in China.

Molecularly imprinted polymers on a silica surface for the adsorption of tobacco-specific nitrosamines in mainstream cigarette smoke.

Tobacco-specific nitrosamines are one of the most important groups of carcinogens in tobacco products. Using adsorbents as filter additives is an effective way to reduce tobacco-specific nitrosamines in cigarette smoke. Molecularly imprinted polymers (MIPs) using nicotinamide as template were grafted on the silica gel surface to obtain MIP@SiO2 and employed as filter additives to absorb tobacco-specific nitrosamines in mainstream cigarette smoke. Four milligrams of MIP@SiO2 per cigarette was added to the interface between filter and tobacco rod to prepare a binary filter system. The mainstream smoke was collected on an industry-standard Cambridge filter pad and extracted with ammonium acetate aqueous solution before analysis. Compared to the cigarette smoke of the control group, the levels of tobacco-specific nitrosamines with silica gel and with MIP@SiO2 were both reduced, and the adsorption rates of N-nitrosonornicotine, N-nitrosoanabasine, N-nitrosoanatabine, and 4-(methylnitrosamino)-1-(3-pyridine)-1-butanone with silica gel and with MIP@SiO2 were 20.76, 15.32, 18.79, and 18.01%, and 41.33, 34.04, 37.86, and 35.53%, respectively. Furthermore the content of total particle materials in cigarette smoke with silica gel was decreased evidently but showed no observable change with MIP@SiO2 . It indicated MIP@SiO2 could selectively reduce tobacco-specific nitrosamines in the mainstream cigarette smoke with no change to the cigarette flavor.

Evidence supporting product standards for carcinogens in smokeless tobacco products.

Smokeless tobacco products sold in the United States vary significantly in yields of nicotine and tobacco-specific nitrosamines (TSNA). With the passage of the Family Smoking Prevention and Tobacco Control Act, the Food and Drug Administration now has the authority to establish product standards. However, limited data exist determining the relative roles of pattern of smokeless tobacco use versus constituent levels in the smokeless tobacco product in exposure of users to carcinogens. In this study, smokeless tobacco users of brands varying in nicotine and TSNA content were recruited from three different regions in the U.S. Participants underwent two assessment sessions. During these sessions, demographic and smokeless tobacco use history information along with urine samples to assess biomarkers of exposure and effect were collected. During the time between data collection, smokeless tobacco users recorded the amount and duration of smokeless tobacco use on a daily basis using their diary cards. Results showed that independent of pattern of smokeless tobacco use and nicotine yields, levels of TSNA in smokeless tobacco products played a significant role in carcinogen exposure levels. Product standards for reducing levels of TSNA in smokeless tobacco products are necessary to decrease exposure to these toxicants and potentially to reduce risk for cancer.

TSNA Exposure: Levels of NNAL Among Canadian Tobacco Users.

Tobacco smoke contains more than 7,000 chemicals, including known carcinogens, such as tobacco-specific nitrosamines (TSNAs). TSNA levels in cigarettes vary considerably within and across markets; however, the extent to which these different TSNA levels translate into differences in human exposure and risk remains unclear. The current study sought to examine TSNA exposure among Canadian tobacco users. Data from the 2007-2009 Canadian Health Measures Survey were used to measure levels of urinary NNAL [4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol], a metabolite of the TSNA NNK [4-(methylnitrosamino-1-(3-pyridyl)-1-butanone], among tobacco users (n = 507). Geometric mean concentrations of total urinary NNAL and creatinine-corrected total urinary NNAL were calculated. A linear regression model was used to examine predictors of urinary levels of NNAL. The mean population level of total urinary NNAL and creatinine-corrected total urinary NNAL was 71.2 pg/ml and 82.0 pg/mg creatinine, respectively. NNAL levels were higher among older respondents (p = .02), among females (p = .04), and among those with greater daily cigarette consumption (p < .0001), greater levels of urinary free cotinine (p < .0001), and greater levels of urinary creatinine (p < .0001). Overall, the mean level of urinary total NNAL among Canadian tobacco users was approximately one fourth that of their U.S. counterparts. The study findings provide the first nationally representative characterization of TSNA exposure among Canadian tobacco users. Although the findings indicate marked differences in TSNA exposure between Canadian and American populations of tobacco users, it is not known whether these differences in exposure translate into differences in risk.

INFLUENCE OF NITROGEN RATE AND FOLIAR FERTILIZATION ON YIELD, QUALITY, AND LEAF CHEMISTRY IN BURLEY TOBACCO

Many burley tobacco (Nicotiana tabacum L.) producers are convinced that additions of nitrogen (N) rates greater than those recommended by university Extension services will result in increased yield and income. Some producers apply foliar fertilizer with other management operations to increase yield and quality of burley tobacco, but these results have not been confirmed by research. Concerns with excessive N additions include improper curing, elevated levels of tobacco-specific nitrosamines, undesirable burning characteristics of the cured leaf, unnecessary fertilizer costs, and negative impacts to environmental quality. A field study was conducted at Lexington, KY and Springfield, TN from 2000 to 2002 to determine the effects of 3 N rates (200, 250, and 300 lb/acre) and 3 foliar fertilizer products on yield and quality on burley tobacco leaf. Nitrogenous leaf compounds were measured only at the Kentucky location. Results from this study indicate that there was no significant yield or quality advantage i...

Exposure to nitrosamines in thirdhand tobacco smoke increases cancer risk in non-smokers

In addition to passive inhalation, non-smokers, and especially children, are exposed to residual tobacco smoke gases and particles that are deposited to surfaces and dust, known as thirdhand smoke (THS). However, until now the potential cancer risks of this pathway of exposure have been highly uncertain and not considered in public health policy. In this study, we estimate for the first time the potential cancer risk by age group through non-dietary ingestion and dermal exposure to carcinogen N-nitrosamines and tobacco-specific nitrosamines (TSNAs) measured in house dust samples. Using a highly sensitive and selective analytical approach we have determined the presence of nicotine, eight N-nitrosamines and five tobacco-specific nitrosamines in forty-six settled dust samples from homes occupied by both smokers and non-smokers. Using observations of house dust composition, we have estimated the cancer risk by applying the most recent official toxicological information. Calculated cancer risks through exposure to the observed levels of TSNAs at an early life stage (1 to 6years old) exceeded the upper-bound risk recommended by the USEPA in 77% of smokers' and 64% of non-smokers' homes. The maximum risk from exposure to all nitrosamines measured in a smoker occupied home was one excess cancer case per one thousand population exposed.The results presented here highlight the potentially severe long-term consequences of THS exposure, particularly to children, and give strong evidence of its potential health risk and, therefore, they should be considered when developing future environmental and health policies.

Determination of amounts of tar, nicotine, carbon monoxide, and tobacco-specific nitrosamines in the fillers of and mainstream smoke from privately imported cigarettes.

The tobacco tax in Japan was increased in October, 2010. Subsequently, the quantity of sales of domestic cigarette products decreased temporarily. However, smokers could import cigarettes directly through the internet. Because of the high value of the yen and the low price of foreign cigarettes, an individual could import cigarettes easily; however, the contents and emissions from privately imported cigarettes have not been investigated yet. In this study, we carried out a comparative analysis of domestic and privately imported cigarettes. Privately imported cigarettes from five brands and domestic cigarettes from the brand "Mild Seven" were selected for the study. For the fillers of the cigarettes, the levels of nicotine and tobacco-specific nitrosamines (TSNAs) were determined by methods that are usually used for cigarette products. For the mainstream smoke, the levels of tar, nicotine, carbon monoxide, and TSNAs were also determined by the methods used for cigarettes. The average nicotine and TSNA levels in the fillers of the domestic cigarettes were 15.1 ± 0.19 mg/g and 1,920 ± 85.1 ng/g, respectively. The amounts of nicotine and tar in the mainstream smoke from the privately imported cigarettes were lower than those from the domestic cigarettes. However, the levels of TSNAs in the mainstream smoke from the privately imported cigarettes were higher than those from the domestic cigarettes. The amounts of TSNAs in the fillers of and mainstream smoke from the privately imported cigarettes were higher than those from the domestic cigarettes. Japanese smokers should be careful about consuming privately imported cigarettes because there is a variation in the amount of hazardous constituents in these cigarettes, even when they are from the same brand.

Measurement of hazardous chemical constituents and mutagenic activity in fillers and mainstream smoke from Neo Cedar

To determine constituents of fillers and mainstream smoke from Neo Cedar. Neo Cedar is a second-class over-the-counter (OTC) drug and similar to cigarettes in a number of ways. In particular, the design and usage are very similar to those of cigarettes. For the fillers of the drug, the levels of nicotine, tobacco-specific nitrosamines (TSNA), and heavy metals, and mutagenicity were determined using the methods for cigarette products. For the mainstream smoke, the levels of tar, nicotine, carbon monoxide (CO), TSNA, polycyclic aromatic hydrocarbons (PAH), and carbonyl compounds were also determined using the methods for cigarettes. The mainstream smoke from the drug were collected with a smoking machine using two smoking protocols (ISO and Health Canada Intense methods). The nicotine and total TSNA levels in the fillers of the drug averaged 2.86 mg/g and 185 ng/g, respectively. The nine species of heavy metals were also detected in the fillers of the drug. The levels of nicotine, tar, CO, TSNA, PAH, and carbonyl compounds of mainstream smoke from the drug were higher when determined using the HCI regime than when using the ISO regime. The mutagenicity of the mainstream smoke determined using the HCI regime was also higher than that determined using the ISO regime. In this study, all constituents of Neo Cedar were determined by methods for cigarette products. The drug had a ventilation hole on its filter. Thus, its constituents are different from those determined by the smoking protocols. Neo Cedar users should be careful of higher exposure to the hazardous gases owing to smoking patterns.

TSNA levels in machine-generated mainstream cigarette smoke: 35 years of data

This paper characterizes historical and current tobacco specific nitrosamine (TSNA) levels in mainstream (MS) cigarette smoke of US commercial cigarettes. To conduct this analysis, we gathered 35years of published data of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN) levels in MS cigarette smoke. We also assessed internal data of MS smoke NNK and NNN levels generated from various market monitoring initiatives and from control cigarettes used in a multi-year program for testing cigarette ingredients. In all, we analyzed machine smoking data from 401 cigarette samples representing a wide range of products and design characteristics from multiple manufacturers and market leaders. There was no indication that TSNA levels systematically increased in cigarette MS smoke over the 35-year analysis period. In particular, TSNA levels expressed as either per cigarette or normalized for tar suggest a downward trend in MS smoke over the past 10years. The apparent downward trend in TSNA levels in MS smoke may reflect industry and agricultural community efforts to reduce levels of TSNAs in tobacco and cigarette smoke.

Chemical Analysis of Alaskan Iq'mik Smokeless Tobacco

Iq'mik, a form of smokeless tobacco (ST), is traditionally used by Cup'ik and Yup'ik Eskimo people of western Alaska. Iq'mik is sometimes incorrectly considered to be a healthier alternative to smoking because its ingredients are perceived as "natural." Our chemical characterization of iq'mik shows that iq'mik is not a safe alternative to smoking or other ST use. We measured nicotine and pH levels of tobacco and ash used to prepare iq'mik. We also characterized levels of toxins which are known to be present in ST including tobacco-specific nitrosamines (TSNAs) and polycyclic aromatic hydrocarbons (PAHs) using chromatographic separations coupled with isotope dilution mass spectrometry. Nicotine content in the iq'mik tobacco was very high, ranging from 35 to 43 mg/g, with a mean of 39 mg/g. The pH of the iq'mik tobacco-ash mixture was 11, an extremely high level compared with most ST products. High levels of PAHs were seen in the fire-cured tobacco samples with a benzo[a]pyrene level of 87 ng/g. Average TSNA levels in the tobacco were 34, 2,700, and 340 ng/g for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), N'-nitrosonornicotine (NNN), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), respectively. Iq'mik contains high levels of the more easily absorbed unionized nicotine as well as known carcinogenic TSNAs and PAHs. The perception that iq'mik is less hazardous than other tobacco products due to the use of "natural" ingredients is not warranted. This chemical characterization of iq'mik gives a better understanding of the risk of possible adverse health effects of its use.

Impact of Alleles at the Yellow Burley (Yb) Loci and Nitrogen Fertilization Rate on Nitrogen Utilization Efficiency and Tobacco-Specific Nitrosamine (TSNA) Formation in Air-Cured Tobacco

Tobacco-specific nitrosamine (TSNA) formation in tobacco is influenced by alkaloid levels and the availability of nitrosating agents. Tobacco types differ in their potential for TSNA accumulation due to genetic, agronomic, and curing factors. Highest TSNA concentrations are typically measured in burley tobaccos. One of the main genetic differences between burley and all other tobacco types is that this tobacco type is homozygous for recessive mutant alleles at the Yellow Burley 1 (Yb(1)) and Yellow Burley 2 (Yb(2)) loci. In addition, burley tobacco is typically fertilized at higher nitrogen (N) rates than most other tobacco types. This study utilized nearly isogenic lines (NILs) differing for the presence of dominant or recessive alleles at the Yb(1) and Yb(2) loci to investigate the potential influence of genes at these loci on TSNA accumulation. Three pairs of NILs were evaluated at three different nitrogen fertilization rates for alkaloid levels, nitrogen physiology measures, and TSNA accumulation after air-curing. As previously observed by others, positive correlations were observed between N application rates and TSNA accumulation. Recessive alleles at Yb(1) and Yb(2) were associated with increased alkaloid levels, reduced nitrogen use efficiency, reduced nitrogen utilization efficiency, and increased leaf nitrate nitrogen (NO(3)-N). Acting together, these factors contributed to significantly greater TSNA levels in genotypes possessing the recessive alleles at these two loci relative to those carrying the dominant alleles. The chlorophyll-deficient phenotype conferred by the recessive yb(1) and yb(2) alleles probably contributes in a substantial way to increase available NO(3)-N during curing and, consequently, increased potential for TSNA formation.

Abstract 667: Evaluation of toxicant exposure in U.S. smokers after short-term switching to commercial low-nitrosamine cigarettes

Abstract Mandated reduction of carcinogens and toxicants in cigarette smoke can be required by the U.S. Food and Drug Administration (FDA). Among the initial smoke constituents proposed for regulation are the carcinogenic tobacco-specific nitrosamines (TSNA) 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and Nα-nitrosonornicotine (NNN), which are believed to play an important role in the development of cancers of the lung, pancreas, oral cavity, and esophagus in smokers. Smoking-machine based measurements demonstrate significant variations in TSNA levels both internationally and among currently marketed U.S. brands. However, human smoking patterns are highly complex, and the machine smoking approach does not provide accurate information on actual TSNA intake by individual smokers. Identification of the machine-measured TSNA levels that can result in significant reduction of their current average intake, as determined by changes in biomarker levels in smokers, is critical in informing future FDA policies. In this study, 18 smokers of cigarettes with relatively high machine-measured smoke concentrations of NNK and NNN were asked to switch to Marlboro Virginia Blend (MVB) - cigarettes with the lowest known TSNA levels on the U.S. market. Urinary levels of cotinine, total NNAL, total NNN, and 1-hydroxypyrene (1-HOP) - biomarkers of exposure to nicotine, NNK, NNN, and polycyclic aromatic hydrocarbons (PAH), respectively - were measured at baseline and after one week of smoking MVB. Average(±SD) levels of carcinogen biomarkers at baseline were: total NNAL, 1.0(±0.7) pmol/mg creatinine; total NNN, 0.034(±0.03) pmol/mg creatinine; and 1-HOP, 0.78(±0.6) pmol/mg creatinine. Corresponding levels after switching to MVB were 0.71(±0.5), 0.039(±0.04), and 1.04(±0.7) pmol/mg creatinine, respectively, with the changes in the levels relative to baseline not being statistically significant. Adjustment for nicotine intake revealed a decrease in urinary total NNAL, total NNN, and 1-HOP by 56%, 31%, and 19%, respectively, after switching to MVB compared to baseline. The only statistically significant change was the decrease in total NNAL levels. The lack of significant decrease in exposure to NNN can be explained by the contribution of endogenously formed NNN to the urinary total NNN measured in smokers. The slightly lower levels of pyrene in the smoke of MVB compared to the baseline cigarette brands could have contributed to the modest change in urinary 1-HOP. In summary, our results demonstrate a significant decrease in NNK intake per mg nicotine after short term switching to commercially available low-nitrosamine cigarettes. However, overall exposure to TSNA was greatly influenced by the individual changes in nicotine intake after switching to MVB. Thus, both carcinogen and nicotine levels may need to be modified in order to reach meaningful reductions in carcinogen intake by smokers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 667. doi:1538-7445.AM2012-667