David L Ashley

National Institute of Environmental Health Sciences, Durham, NC, USA

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Publications (51)177.2 Total impact

  • Source
    Article: Chemical characterization of domestic oral tobacco products: total nicotine, pH, unprotonated nicotine and tobacco-specific N-nitrosamines.
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    ABSTRACT: In the United States, moist snuff has been studied more widely than other distinct categories of oral tobacco. In this study, we measured pH, moisture, nicotine (total and unprotonated), and tobacco-specific N-nitrosamines (TSNAs) for other established (twist, loose leaf, plug, and dry snuff without pouch) and emerging oral tobacco products (dry snuff pouch, U.S.-made snus, and dissolvable tobacco). Among the seven product categories, product pH ranged from 4.7 - 7.9, and total nicotine concentration spanned from 3.9 - 40.1 mg/g. The most readily absorbable form of nicotine (unprotonated nicotine) varied more than 350-fold, ranging from 0.01 - 3.7 mg/g. While the highest total nicotine concentrations were observed in twist products, snus and dissolvable tobacco had the highest unprotonated nicotine levels. Among all products, total TSNA concentrations ranged from 313 - 76,500 ng/g with dry snuff having the highest total TSNA concentrations. This study demonstrates the diversity among oral tobacco products and highlights the potential of these products to deliver a wide range of nicotine and carcinogenic TSNAs. Characterizing the chemical content of these products may be helpful in further understanding the risk of marketing these products to oral tobacco users and smokers as an alternative and discrete form of tobacco.
    Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 03/2013; · 2.99 Impact Factor
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    Article: Chemical Analysis of Alaskan Iq'mik Smokeless Tobacco.
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    ABSTRACT: INTRODUCTION: 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. METHODS: 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. RESULTS: Nicotine content in the iq'mik tobacco was very high, ranging from 35 to 43mg/g, with a mean of 39mg/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 87ng/g. Average TSNA levels in the tobacco were 34, 2,700, and 340ng/g for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), N'-nitrosonornicotine (NNN), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), respectively. CONCLUSIONS: 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.
    Nicotine & Tobacco Research 01/2013; · 2.58 Impact Factor
  • Article: The Food and Drug Administration's Regulation of Tobacco: The Center for Tobacco Products' Office of Science.
    David L Ashley, Cathy L Backinger
    American journal of preventive medicine 11/2012; 43(5 Suppl 3):S255-63. · 4.24 Impact Factor
  • Article: Simultaneous analysis of 28 urinary VOC metabolites using ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI/MSMS).
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    ABSTRACT: Volatile organic compounds (VOCs) are ubiquitous in the environment, originating from many different natural and anthropogenic sources, including tobacco smoke. Long-term exposure to certain VOCs may increase the risk for cancer, birth defects, and neurocognitive impairment. Therefore, VOC exposure is an area of significant public health concern. Urinary VOC metabolites are useful biomarkers for assessing VOC exposure because of non-invasiveness of sampling and longer physiological half-lives of urinary metabolites compared with VOCs in blood and breath. We developed a method using reversed-phase ultra high performance liquid chromatography (UPLC) coupled with electrospray ionization tandem mass spectrometry (ESI/MSMS) to simultaneously quantify 28 urinary VOC metabolites as biomarkers of exposure. We describe a method that monitors metabolites of acrolein, acrylamide, acrylonitrile, benzene, 1-bromopropane, 1,3-butadiene, carbon-disulfide, crotonaldehyde, cyanide, N,N-dimethylformamide, ethylbenzene, ethylene oxide, propylene oxide, styrene, tetrachloroethylene, toluene, trichloroethylene, vinyl chloride and xylene. The method is accurate (mean accuracy for spiked matrix ranged from 84 to104%), sensitive (limit of detection ranged from 0.5 to 20ngmL(-1)) and precise (the relative standard deviations ranged from 2.5 to 11%). We applied this method to urine samples collected from 1203 non-smokers and 347 smokers and demonstrated that smokers have significantly elevated levels of tobacco-related biomarkers compared to non-smokers. We found significant (p<0.0001) correlations between serum cotinine and most of the tobacco-related biomarkers measured. These findings confirm that this method can effectively quantify urinary VOC metabolites in a population exposed to volatile organics.
    Analytica chimica acta 10/2012; 750:152-60. · 4.31 Impact Factor
  • Article: The influence of physicochemical properties on the internal dose of trihalomethanes in humans following a controlled showering exposure.
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    ABSTRACT: Although disinfection of domestic water supply is crucial for protecting public health from waterborne diseases, this process forms potentially harmful by-products, such as trihalomethanes (THMs). We evaluated the influence of physicochemical properties of four THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) on the internal dose after showering. One hundred volunteers showered for 10 min in a controlled setting with fixed water flow, air flow, and temperature. We measured THMs in shower water, shower air, bathroom air, and blood samples collected at various time intervals. The geometric mean (GM) for total THM concentration in shower water was 96.2 μg/l. The GM of total THM in air increased from 5.8 μg/m(3) pre shower to 351 μg/m(3) during showering. Similarly, the GM of total-blood THM concentration increased from 16.5 ng/l pre shower to 299 ng/l at 10 min post shower. THM levels were significantly correlated between different matrices (e.g. dibromochloromethane levels) in water and air (r=0.941); blood and water (r=0.845); and blood and air (r=0.831). The slopes of best-fit lines for THM levels in water vs air and blood vs air increased with increasing partition coefficient of water/air and blood/air. The slope of the correlation plot of THM levels in water vs air decreased in a linear (r=0.995) fashion with increasing Henry's law constant. The physicochemical properties (volatility, partition coefficients, and Henry's law constant) are useful parameters for predicting THM movement between matrices and understanding THM exposure during showering.Journal of Exposure Science and Environmental Epidemiology advance online publication, 25 July 2012; doi:10.1038/jes.2012.80.
    Journal of Exposure Science and Environmental Epidemiology 07/2012; · 2.93 Impact Factor
  • Article: Tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in smokers in the United States: NHANES 2007-2008.
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    ABSTRACT: The tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of the tobacco-specific nitrosamine (TSNA) 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), has been measured in urine samples from all participants aged 6 years and older from the National Health and Nutrition Examination Survey 2007-2008. Participants with a serum cotinine concentration of ≥ 10 ng/mL were identified as tobacco users, primarily cigarette smokers. Regression models were developed to calculate geometric mean NNAL concentrations adjusted for serum cotinine, urinary creatinine, cigarettes per day, and Federal Trade Commission tar values of the cigarettes smoked. Significant differences were found by gender (p=0.003) and race/ethnicity (p=0.022 for non-Hispanic white versus non-Hispanic black smokers), but not by menthol type of the cigarettes. Females and non-Hispanic white smokers had the highest adjusted means for urinary NNAL (353 and 336 pg/mL, respectively). The results from this study demonstrated significant relationships between NNAL concentrations and serum cotinine (p<0.001) and urine creatinine (p<0.001). The joint effect of linear and quadratic terms for number of cigarettes smoked per day was also statistically significant (p=0.001). In addition to addressing current NNK exposure levels, these results will form a baseline for future estimates of tobacco users' exposure to this carcinogen.
    Biomarkers 03/2011; 16(2):112-9. · 2.21 Impact Factor
  • Article: Quantitative analysis of six heterocyclic aromatic amines in mainstream cigarette smoke condensate using isotope dilution liquid chromatography-electrospray ionization tandem mass spectrometry.
    Liqin Zhang, David L Ashley, Clifford H Watson
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    ABSTRACT: Heterocyclic aromatic amines (HAAs) represent an important class of carcinogens in mainstream cigarette smoke. Accurate HAA quantification is challenging because of their relative low abundances and numerous chemical interferences that arise naturally from thousands of the constituents present in cigarette smoke. We have developed and validated a straightforward high-throughput method to quantify HAA levels in mainstream cigarette smoke and demonstrated the applicability by analyzing select research and domestic cigarette brands. Machine-smoked cigarette condensate collected under both standard and intensive smoking regimens was examined. Mainstream smoke particulate from individual cigarettes trapped on a glass fiber filter pad was spiked with an appropriate internal standard solution and subsequently solvent extracted. The extract was quantitatively analyzed by high-performance liquid chromatography and tandem mass spectrometry. Method validation data showed excellent accuracy, reproducibility and high throughput; it is suitable for the routine analysis of HAAs in cigarette smoke condensate delivered under a wide of differing smoking conditions. The smoking machine deliveries of HAAs are strongly influenced by cigarettes' physical design, filler blend, and smoking regimen. A quick and accurate method has been developed for the analysis of 6 HAAs in mainstream cigarette smoke condensate. Results provided a good mean to access the ranges of HAAs in commercial products and evaluate the relative contribution of cigarette design, filler blend, and smoking regimen on delivery. Such data are vital in helping provide exposure ranges for potential human exposure estimates.
    Nicotine & Tobacco Research 02/2011; 13(2):120-6. · 2.58 Impact Factor
  • Article: Urine concentrations of a tobacco-specific nitrosamine carcinogen in the U.S. population from secondhand smoke exposure.
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    ABSTRACT: The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its reduction product in the body, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), are potent pulmonary carcinogens. We have measured total NNAL in the U.S. population of tobacco users and nonsmokers exposed to secondhand smoke. We measured total urinary NNAL (free NNAL plus its glucuronides following hydrolysis) by using a sensitive and specific high-performance liquid chromatography/tandem mass spectrometry method. We calculated the percentage above the limit of detection, the 50th through 95th percentiles, and in some cases, geometric means for groups classified by age, gender, and race/ethnicity. Total urinary NNAL was measureable at or above its limit of detection (0.6 pg/mL) in 55% of the study participants, including 41% of nonsmokers. The population distribution of urinary NNAL included smoker and nonsmoker regions similar to the bimodal distribution of serum cotinine, and serum cotinine and total urinary NNAL were strongly correlated (r = 0.92; P < 0.001). Among nonsmokers, children had significantly higher concentrations of NNAL than did adults with the age of ≥20 years (P < 0.001). Among National Health and Nutrition Examination Survey participants, total NNAL was found at measurable levels in the urine of 41% of nonsmokers and in 87.5% of those with substantial secondhand-smoke exposure (with serum cotinine concentrations of 0.1-10 ng/mL). Children with the age of 6 to 11 years had the highest NNAL concentrations among all nonsmokers. We describe for the first time the distribution of total urinary NNAL in the entire U.S. population, including smokers and nonsmokers. NNAL was detected in 41% of all nonsmokers.
    Cancer Epidemiology Biomarkers &amp Prevention 11/2010; 19(11):2969-77. · 4.12 Impact Factor
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    Article: Global surveillance of oral tobacco products: total nicotine, unionised nicotine and tobacco-specific N-nitrosamines.
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    ABSTRACT: Oral tobacco products contain nicotine and carcinogenic tobacco-specific N-nitrosamines (TSNAs) that can be absorbed through the oral mucosa. The aim of this study was to determine typical pH ranges and concentrations of total nicotine, unionised nicotine (the most readily absorbed form) and five TSNAs in selected oral tobacco products distributed globally. A total of 53 oral tobacco products from 5 World Health Organisation (WHO) regions were analysed for total nicotine and TSNAs, including 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), using gas chromatography or liquid chromatography with mass spectrometric detection. Unionised nicotine concentrations were calculated using product pH and total nicotine concentrations. Fourier transform infrared spectroscopy was used to help categorize or characterise some products. Total nicotine content varied from 0.16 to 34.1 mg/g product, whereas, the calculated unionised nicotine ranged from 0.05 to 31.0 mg/g product; a 620-fold range of variation. Products ranged from pH 5.2 to 10.1, which translates to 0.2% to 99.1% of nicotine being in the unionised form. Some products have very high pH and correspondingly high unionised nicotine (eg, gul powder, chimó, toombak) and/or high TSNA (eg, toombak, zarda, khaini) concentrations. The concentrations of TSNAs spanned five orders of magnitude with concentrations of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) ranging from 4.5 to 516,000 ng/g product. These data have important implications for risk assessment because they show that very different exposure risks may be posed through the use of these chemically diverse oral tobacco products. Because of the wide chemical variation, oral tobacco products should not be categorised together when considering the public health implications of their use.
    Tobacco control 11/2010; 20(3):e2. · 3.85 Impact Factor
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    Article: Nicotine reduction revisited: science and future directions.
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    ABSTRACT: Regulation of nicotine levels in cigarettes and other tobacco products is now possible with the passage of the Family Smoking Prevention and Tobacco Control Act (FSPTCA) in 2009, giving the US Food and Drug Administration (FDA) authority to regulate tobacco products, and with Articles 9-11 of the WHO Framework Convention on Tobacco Control. Both regulatory approaches allow establishing product standards for tobacco constituents, including nicotine. The FSPTCA does not allow nicotine levels to be decreased to zero, although the FDA has the authority to reduce nicotine yields to very low, presumably non-addicting levels. The proposal to reduce levels of nicotine to a level that is non-addicting was originally suggested in 1994. Reduction of nicotine in tobacco products could potentially have a profound impact on reducing tobacco-related morbidity and mortality. To examine this issue, two meetings were convened in the US with non-tobacco-industry scientists of varied disciplines, tobacco control policymakers and representatives of government agencies. This article provides an overview of the current science in the area of reduced nicotine content cigarettes and key conclusions and recommendations for research and policy that emerged from the deliberations of the meeting members.
    Tobacco control 10/2010; 19(5):e1-10. · 3.85 Impact Factor
  • Article: Semi-volatiles in mainstream smoke delivery from select charcoal-filtered cigarette brand variants.
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    ABSTRACT: It has been reported that charcoal added to cigarette filters selectively removes many of the more volatile chemicals, but it is not clear to what extent charcoal may reduce the delivery of important less volatile chemical constituents in mainstream cigarette smoke. We analysed machine-derived mainstream smoke deliveries (under three smoking regimens) for variants of a charcoal-filtered cigarette commercially test-marketed in the USA, focusing on selected polycyclic aromatic hydrocarbons (PAHs), phenols and tobacco-specific nitrosamines (TSNAs). While charcoal-containing filters selectively removed lower molecular weight PAHs from mainstream smoke, they did not significantly remove the heavier and more toxic PAHs studied, such as benzo[a]pyrene, a known carcinogen. Likewise, charcoal-containing filters removed phenols and TSNAs from mainstream smoke to differing amounts depending on the compound, filter design and the smoking regimen. The addition of sufficient charcoal to cigarette filters is known to remove many volatile compounds and can potentially reduce deliveries of certain semi-volatile compounds under some machine smoking regimens. Less volatile compounds, with a significant portion in the particulate phase, are less available for selective filtration by charcoal-containing filters than the more volatile compounds that reside predominantly in the gas phase.
    Tobacco control 06/2010; 19(3):223-30. · 3.85 Impact Factor
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    Article: Effect of differing levels of tobacco-specific nitrosamines in cigarette smoke on the levels of biomarkers in smokers.
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    ABSTRACT: Smokers are exposed to significant doses of carcinogens, including tobacco-specific nitrosamines (TSNA). Previous studies have shown significant global differences in the levels of TSNAs in cigarette smoke because of the variation in tobacco blending and curing practices around the world. Mouth-level exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) measured in cigarette butts and urinary concentrations of its major metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) were examined among 126 daily smokers in four countries over a 24-hour study period. As mouth-level exposure of NNK increased, the urinary NNAL increased even after adjustment for other covariates (beta = 0.46, P = 0.004). The relationship between mouth-level exposure to nicotine and its salivary metabolite, cotinine, was not statistically significant (beta = 0.29, P = 0.057), likely because of the very limited range of differences in mouth-level nicotine exposure in this population. We have shown a direct association between the 24-hour mouth-level exposure of NNK resulting from cigarette smoking and the concentration of its primary metabolite, NNAL, in the urine of smokers. Internal dose concentrations of urinary NNAL are significantly lower in smokers in countries that have lower TSNA levels in cigarettes such as Canada and Australia in contrast to countries that have high levels of these carcinogens in cigarettes, such as the United States. Lowering the levels of NNK in the mainstream smoke of cigarettes through the use of specific tobacco types and known curing practices can significantly affect the exposure of smokers to this known carcinogen.
    Cancer Epidemiology Biomarkers &amp Prevention 06/2010; 19(6):1389-98. · 4.12 Impact Factor
  • Article: Estimating smokers' mouth-level exposure to select mainstream smoke constituents from discarded cigarette filter butts.
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    ABSTRACT: Standardized machine smoking measurements are poor predictors of exposure. We have refined a method using the solanesol deposited in discarded cigarette butts as a marker for estimating deliveries of mainstream smoke constituents. Developing a fast and accurate method for measuring solanesol in cigarette filters to assess tobacco smoke intake could provide a way to assess how people smoke under natural conditions. We have developed and validated a new, lower-cost, high-throughput method to measure the solanesol content in discarded cigarette filter butts and correlated these measurements with mainstream smoke deliveries of nicotine and tobacco-specific nitrosamines (TSNAs). Cigarettes were machine smoked under a variety of conditions to cover a wide range of nicotine deliveries and solanesol levels in the spent cigarette filter. Following machine smoking, a 1-cm portion of filter material, measured from the mouth end, was removed from the cigarette butts for analysis. Although an isotopically labeled solanesol analog is currently not commercially available, we achieved excellent quantitative results using a structurally similar compound, geranylgeraniol, as an internal standard (IS). After spiking with IS and solvent extracted, solanesol extracts were then analyzed using liquid chromatography coupled with a single-quadrupole mass analyzer. Analysis was carried out using manual preparation as well as a high-throughput 48-well format using automated liquid handlers. Recoveries of solanesol from cigarette butts exceeded 95% with excellent precision and exhibited excellent linearity for both preparation methods. In addition, we show that the mouth-level exposure for both nicotine and TSNAs may be estimated by their relation to the solanesol retained in the cigarette filter. We believe that this method provides excellent versatility and throughput for the estimation of mouth-level exposure to a wide range of toxins in cigarette smoke under naturalistic conditions. In addition, this method allows a far more accurate measure of exposure both from a single cigarette as well as from daily smoking.
    Nicotine & Tobacco Research 08/2009; 11(7):868-74. · 2.58 Impact Factor
  • Article: Simultaneous determination of six mercapturic acid metabolites of volatile organic compounds in human urine.
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    ABSTRACT: The widespread exposure to potentially harmful volatile organic compounds (VOCs) merits the development of practical and accurate exposure assessment methods. Measuring the urinary concentrations of VOC mercapturic acid (MA) metabolites provides noninvasive and selective information about recent exposure to certain VOCs. We developed a liquid chromatography-tandem mass spectrometry method for quantifying urinary levels of six MAs: N-acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA), N-acetyl-S-(3-hydroxypropyl)-L-cysteine (HPMA), N-acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine (MHBMA), N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), N-acetyl-S-(2-hydroxyethyl)-L-cysteine (HEMA), and N-acetyl-S-(phenyl)-L-cysteine (PMA). The method provides good accuracy (102% mean accuracy) and high precision (3.5% mean precision). The sensitivity (limits of detection of 0.01-0.20 microg/L) and wide dynamic detection range (0.025-500 microg/L) make this method suitable for assessing VOC exposure of minimally exposed populations and those with significant exposures, such as cigarette smokers. We used this method to quantify MA levels in urine collected from smokers and nonsmokers. Median levels of creatinine-corrected CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA among nonsmokers (n = 59) were 38.1, 24.3, 21.3, 104.7, 0.9, and 0.5 microg/g creatinine, respectively. Among smokers (n = 61), median levels of CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA were 214.4, 839.7, 10.2, 509.7, 2.2, and 0.9 microg/g creatinine, respectively. All VOC MAs measured were higher among smokers than among nonsmokers, with the exception of MHBMA.
    Chemical Research in Toxicology 07/2009; 22(6):1018-25. · 3.78 Impact Factor
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    Article: Increases in tobacco exposure biomarkers measured in non-smokers exposed to sidestream cigarette smoke under controlled conditions.
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    ABSTRACT: National surveys of the exposure of non-smokers to secondhand smoke based on serum cotinine analyses have consistently identified certain groups within the population including children, males and non-Hispanic Blacks as having relatively greater exposure. Although these differences in mean serum cotinine concentrations probably represent differences in exposure of individuals in their daily lives, it is also possible that metabolic or other differences in response might influence the results. To better define the nature of those findings, we have examined the response of 40 non-smokers including both men and women and African-Americans and whites to sidestream (SS) cigarette smoke generated by a smoking machine under controlled conditions. In this study, participants were exposed to aged, diluted SS smoke (ADSS) generated in an environmental chamber with a mean air nicotine concentration of 140 microg m(-3) and 8.6 ppm CO for 4 h. Salivary cotinine was measured every 30 min, and serum cotinine samples were taken prior to, and 2 h after exposure. Urinary nicotine metabolites and NNAL, a tobacco-specific nitrosamine, and 4-aminobiphenyl (4-AB) haemoglobin adducts were also measured prior to and 2 h following the exposure. Under these uniform, controlled conditions, we found a similar response to ADSS smoke exposure among all the participants. In all cases a significant increase in biomarker concentration was noted following exposure, and the short-term increases in salivary cotinine concentration were quite similar at approximately 12 pg ml(-1) min(-1) among the groups. In this small study, no significant differences by gender or race were seen in the mean increases observed in cotinine, NNAL or 4-AB adducts following 4 h of exposure. Thus, our results are most consistent with a relatively uniform response in tobacco biomarker concentrations following short-term exposure to ADSS tobacco smoke, and suggest that biomarker measurements are capable of effectively indicating increases in exposure among groups of non-smokers.
    Biomarkers 04/2009; 14(2):82-93. · 2.21 Impact Factor
  • Article: Approaches, challenges, and experience in assessing free nicotine.
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    ABSTRACT: Delivery of nicotine in the most desirable form is critical in maintaining people's use of tobacco products. Interpretation of results by tobacco industry scientists, studies that measure free-base nicotine directly in tobacco smoke, and the variability of free-base nicotine in smokeless tobacco products all indicate that the form of nicotine delivered to the tobacco user, in addition to the total amount, is an important factor in whether people continue to use the product following their initial exposure. The physiological impact of nicotine varies with the fraction that is in the free-base form and this leads to continued exposure to other toxic tobacco contents and emissions. In addition to evaluating the total nicotine delivered to the user, measuring the fraction of nicotine in the free-base form is critical in understanding and controlling the influence of nicotine on tobacco use.
    Handbook of experimental pharmacology 02/2009;
  • Article: Levels of tobacco-specific nitrosamines and polycyclic aromatic hydrocarbons in mainstream smoke from different tobacco varieties.
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    ABSTRACT: It has been estimated that one in every five cancer deaths worldwide are related to tobacco use. According to the IARC, 10 polycyclic aromatic hydrocarbons (PAH) and 8 tobacco-specific nitrosamines (TSNA), as well as at least 45 other compounds or substances found in tobacco smoke, are potential human carcinogens. The levels of these carcinogens in contents of tobacco and smoke emissions vary between different tobacco products. We evaluated mainstream smoke emissions from cigarettes made with different types of tobacco to examine the relation between their deliveries of TSNAs and PAHs and any possible influence from tobacco nitrate content. To investigate the contribution of tobacco content to mainstream cigarette smoke deliveries without confounders such as filter design, filter ventilation, and paper porosity, we used custom-made, research-grade, unfiltered cigarettes that contained bright, burley, oriental, reconstituted, or mixtures of these tobaccos. Our findings confirm results from other researchers that tobacco type can influence the mainstream smoke delivery of nicotine, TSNAs, and PAHs. However, we found that the effect varies among individual compounds. In addition, we observed a statistically significant relationship between nitrate content and mainstream smoke 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK); nitrate level also influenced the mainstream smoke deliveries of the summed total of the 10 PAHs identified by IARC as potential human carcinogens. The influence of nitrate on mainstream smoke NNK and PAH levels were of different magnitude and direction. Our results tend to indicate an inverse relation exists between NNK and PAH deliveries when considering different tobacco blends.
    Cancer Epidemiology Biomarkers &amp Prevention 01/2009; 17(12):3366-71. · 4.12 Impact Factor
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    Article: Automated determination of seven phenolic compounds in mainstream tobacco smoke.
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    ABSTRACT: Exposure to hydroxyl-substituted arenes, commonly referred to as phenols or phenolic compounds, can have serious health consequences. Select phenols present in tobacco smoke are cardiovascular toxins, act as tumor co-promoters and show genotoxic activity. To examine the mainstream smoke levels of these compounds, we developed and applied a method for quantitative analysis of seven phenols (phenol, o-cresol, m-cresol, p-cresol, catechol, resorcinol, and hydroquinone) in mainstream smoke. Total mainstream smoke particulate matter was collected on a Cambridge filter pad and spiked with an isotopically labeled internal standard solution. This pad underwent an automated phenol derivatization procedure to increase analyte volatility and enhance detection. Following the derivatization step, phenols from the particulate matter were sampled using solid-phase microextraction with subsequent gas chromatography/mass spectrometric detection. Sensitivity, selectivity, accuracy, and reproducibility were more than adequate for routine detection of phenols in mainstream smoke. Detection limits ranged from 0.04-0.57 microg, with a quantification range of 0.1-710 microg. Higher sensitivity and sample throughput were achieved compared with previously described methods. Mainstream smoke from 28 brands of domestic commercial cigarettes was evaluated to assess typical levels, and reference cigarettes containing single tobacco blends were examined to ascertain the phenolic profile from different types of tobaccos. As expected under machine smoking conditions using the Federal Trade Commission parameters, full-flavored cigarettes deliver more phenols than the light varieties, followed by the ultra light varieties. Differences were seen in relative levels of phenolic compounds in the mainstream smoke from unfiltered cigarettes made with a single type of tobacco.
    Nicotine & Tobacco Research 07/2008; 10(7):1261-8. · 2.58 Impact Factor
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    Article: Quantification of fuel oxygenate ethers in human blood using solid-phase microextraction coupled with gas chromatography-high-resolution mass spectrometry.
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    ABSTRACT: Widespread use of fuel oxygenates, coupled with their high water solubility and slow degradation rate, have led to an increase in the potential for human exposure. We developed an accurate, precise, sensitive, and high-throughput analytical method to simultaneously quantify trace levels (low parts-per-trillion) of four fuel oxygenates in human blood: methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE), and tert-amyl methyl ether (TAME). The analytes were extracted from the head space above human blood samples, using solid-phase microextraction, desorbed into the heated injector, and chromatographically resolved by capillary gas chromatography. Analytes were detected by high-resolution mass spectrometry with multiple ion monitoring, and quantified against known standard levels by use of stable isotope-labeled internal standards for recovery correction. The low limits of detection (0.6 ng/L) allowed for measurement of MTBE, ETBE, DIPE, and TAME in parts-per-trillion levels with excellent precision (coefficient of variation ranging from 1.7 to 5.4%) and accuracy (96-100%). This method provides a means to assess fuel oxygenate exposure and study the potential relationship between exposure and adverse health outcomes.
    Journal of analytical toxicology 06/2008; 32(4):273-80. · 2.02 Impact Factor
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    Article: Determination of eugenol, anethole, and coumarin in the mainstream cigarette smoke of Indonesian clove cigarettes.
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    ABSTRACT: Indonesian clove cigarettes (kreteks), typically have the appearance of a conventional domestic cigarette. The unique aspects of kreteks are that in addition to tobacco they contain dried clove buds (15-40%, by wt.), and are flavored with a proprietary "sauce". Whereas the clove buds contribute to generating high levels of eugenol in the smoke, the "sauce" may also contribute other potentially harmful constituents in addition to those associated with tobacco use. We measured levels of eugenol, trans-anethole (anethole), and coumarin in smoke from 33 brands of clove-flavored cigarettes (filtered and unfiltered) from five kretek manufacturers. In order to provide information for evaluating the delivery of these compounds under standard smoking conditions, a quantification method was developed for their measurement in mainstream cigarette smoke. The method allowed collection of mainstream cigarette smoke particulate matter on a Cambridge filter pad, extraction with methanol, sampling by automated headspace solid-phase microextraction, and subsequent analysis using gas chromatography/mass spectrometry. The presence of these compounds was confirmed in the smoke of kreteks using mass spectral library matching, high-resolution mass spectrometry (+/-0.0002 amu), and agreement with a relative retention time index, and native standards. We found that when kreteks were smoked according to standardized machine smoke parameters as specified by the International Standards Organization, all 33 clove brands contained levels of eugenol ranging from 2,490 to 37,900 microg/cigarette (microg/cig). Anethole was detected in smoke from 13 brands at levels of 22.8-1,030 microg/cig, and coumarin was detected in 19 brands at levels ranging from 9.2 to 215 microg/cig. These detected levels are significantly higher than the levels found in commercial cigarette brands available in the United States.
    Food and Chemical Toxicology 11/2007; 45(10):1948-53. · 3.00 Impact Factor