[Show abstract][Hide abstract] ABSTRACT: We compared risk of lung cancer and chronic obstructive pulmonary disease (COPD) associated with flue-cured and blended cigarettes. Mortality and smoking data were collected for 1971-2000 by sex, age, and period for three countries with a mainly flue-cured market and four with a blended market. Epidemiological relative risk estimates for current and ex smoking were summarized. Smoking statistics and mortality were compared between flue-cured cigarette and blended cigarette countries. Unadjusted mortality rates were generally lower in blended cigarette countries early on, with the difference diminishing or reversing by the 1990s. Differences by cigarette type were rarely significant, due to variations, particularly for COPD, between countries within cigarette type. Current smoking prevalence was generally lower in blended cigarette countries in 1971-1975, with the difference reducing over time. Differences by type were never significant, with blended cigarette countries varying markedly. Ex-smoking increased over time and was lower for blended cigarette countries, generally not significantly. Consumption per smoker was somewhat lower for blended cigarette countries. Relative risk estimates for smoking, derived mainly from U.S. and UK studies, varied little by cigarette type. Conclusions based on estimated smoking-related excess mortality were similar to those based on unadjusted mortality rates. There was little indication of any difference between flue-cured and blended cigarettes on risk of lung cancer or COPD. Our approach could have detected differences of about 40% for male lung cancer, or twofold differences for females or for COPD, had they existed. Between-country differences in rates of two major diseases predominantly caused by smoking cannot materially be explained by whether the countries use flue-cured or blended cigarettes.
[Show abstract][Hide abstract] ABSTRACT: Smokeless tobacco is often referred to as a major contributor to oral cancer. In some regions, especially Southeast Asia, the risk is difficult to quantify due to the variety of products, compositions (including non-tobacco ingredients) and usage practices involved. In Western populations, the evidence of an increased risk in smokeless tobacco users seems unclear, previous reviews having reached somewhat differing conclusions. We report a detailed quantitative review of the evidence in American and European smokeless tobacco users, and compare our findings with previous reviews and meta-analyses.
Following literature review a meta-analysis was conducted of 32 epidemiological studies published between 1920 and 2005 including tests for homogeneity and publication bias.
Based on 38 heterogeneous study-specific estimates of the odds ratio or relative risk for smokeless tobacco use, the random-effects estimate was 1.87 (95% confidence interval 1.40-2.48). The increase was mainly evident in studies conducted before 1980. No increase was seen in studies in Scandinavia. Restricting attention to the seven estimates adjusted for smoking and alcohol eliminated both heterogeneity and excess risk (1.02; 0.82-1.28). Estimates also varied by sex (higher in females) and by study design (higher in case-control studies with hospital controls) but more clearly in studies where estimates were unadjusted, even for age. The pattern of estimates suggests some publication bias. Based on limited data specific to never smokers, the random-effects estimate was 1.94 (0.88-4.28), the eight individual estimates being heterogeneous and based on few exposed cases.
Smokeless tobacco, as used in America or Europe, carries at most a minor increased risk of oral cancer. However, elevated risks in specific populations or from specific products cannot definitely be excluded.
BMC Public Health 02/2007; 7:334. · 2.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study has examined the possible effects of ammonia-forming ingredients added to tobacco and of ammonia in mainstream (MS) smoke on the nicotine transfer from tobacco to smoke. The U.S. 1998 Marlboro Lights King Size cigarette was used as a control for four test variants that differed from the control as follows: first, a reduction in ammonia-forming ingredients added to the reconstituted tobaccos; second, no ammonia-forming ingredients added to the reconstituted tobaccos; third, no ingredients at all added to the reconstituted tobaccos; and fourth, no ingredients at all added to the entire tobacco blend. Data were obtained on nicotine in tobacco, tar and nicotine and ammonia in MS smoke, soluble ammonia in the cigarette tobacco, "tobacco pH," and "smoke pH" using the FTC machine-smoking paradigm. Previous research on these cigarettes demonstrated that >99% of the MS smoke nicotine was captured and quantified by the FTC method. Statistically significant increases in soluble ammonia and MS smoke ammonia were observed for those cigarettes with ammonia-forming ingredients added to the reconstituted tobacco. However, ingredients, including ammonia and ammonia-forming compounds added to the tobacco or ammonia in the mainstream smoke in the Marlboro Lights King Size cigarette, did not increase the relative nicotine transfer or the "pH of aqueous extracts of MS smoke." "Tobacco pH" and "smoke pH" had no scientific or practical value for the cigarettes in this study.
Regulatory Toxicology and Pharmacology 10/2006; 46(1):1-17. · 2.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present work summarizes the currently available published studies on lung cancer and occupational acrylonitrile exposure. Meta-analytic methods were used to estimate the overall risk. To adjust for the healthy worker effect, rate ratio estimates based on regression analyses and ratios of standard mortality ratios were aggregated. Overall effect estimates were 0.95 (95% CI 0.86 to 1.06) and 1.25 (95% CI 1.10 to 1.43) before and after adjustment for the healthy worker effect, respectively. Therefore, a 25% increase in lung cancer risk attributable to occupational acrylonitrile exposure is suggested. Possible contribution of smoking confounding the increased risk cannot be fully excluded.
Journal of Environmental Science and Health Part C 02/2006; 24(2):257-84. · 2.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Epidemiological data suggest that smoking filter and lower tar cigarettes is associated with less lung cancer risk than is smoking plain and higher tar cigarettes. A recent National Cancer Institute monograph claimed these apparent benefits of lower delivery products may be illusory if relative risks are adjusted for daily consumption, and switching leads to "compensation" for reduced nicotine intake by increasing numbers of cigarettes smoked. To investigate this, we compared relative risks unadjusted and adjusted for daily cigarette consumption. Overall estimates of the filter/plain relative risk, using random-effects meta-analysis, were 0.61 (95%confidence interval 0.54 to 0.70) for unadjusted data and 0.66 (0.58 to 0.76) for adjusted data. The lower tar/higher tar relative risk was estimated as 0.60 (0.45 to 0.81) for unadjusted data and 0.73 (0.64 to 0.83) for adjusted data. The risk reductions were clearly seen regardless of gender, study location, period, or design, and when only studies providing both unadjusted and adjusted estimates were considered. Whether or not relative risk estimates are adjusted for cigarette consumption is not crucial to the conclusion of a clear advantage to filter cigarettes and tar reduction. Data on "compensation" for amount smoked were reviewed and any increase following switching to reduced-tar-yield cigarettes was shown to be quite small. Other biases in the epidemiology are also discussed, and we conclude that the apparent advantage to reduced-tar-delivery products is real and likely to be a marked underestimate of the reduction in lung cancer risk from lifetime smoking of low-tar cigarettes.
[Show abstract][Hide abstract] ABSTRACT: The hypothesis that elevated levels of ammonia-releasing compounds in tobacco and ammonia in mainstream (MS) smoke increase the rate and amount of nicotine evaporation from the particles of MS smoke aerosol was examined by kinetic modeling and experiments with MS cigarette smoke. Computational simulation of a kinetic mechanism describing volatile loss of nicotine, ammonia, and acetic acid from an aqueous solution was used to compute the time-dependent concentration of all species in the model. Because of the high volatility of ammonia relative to that of nicotine, variation over a wide range of initial ammonia concentration had no significant effect upon the rate of loss of nicotine from the model system. The effects of a variation in the volatile loss rate constant for ammonia and for the acid were examined. The simulations show that ammonia is lost from the model solution at a greater rate than nicotine and acid, and the loss of volatile acid has a significant role in the rate and amount of nicotine loss. Simulations with a model system undergoing a continuous steady addition of ammonia showed that high rates of ammonia addition could significantly increase the rate of nicotine volatile loss from the model solution. A series of smoking experiments was performed using blended cigarettes connected to a denuder tube. Deposition of smoke constituents can occur directly from the gas phase and by the deposition of smoke aerosol particles themselves. As nicotine exists >99% in the particle phase of MS smoke, in the absence of particle deposition, denuder tube deposition of nicotine occurs via the evaporation-deposition pathway. Solanesol, a nonvolatile tobacco and smoke terpene, was used to quantify the amount of particle deposition onto the denuder tube. The amount of ammonia deposited on the denuder tube was an order of magnitude greater than that of nicotine, showing that ammonia evaporates from the MS smoke particles much faster than does nicotine. The experimental results were supported and explained by the aqueous model simulations. Included in these experiments are cigarettes that differ in their MS smoke ammonia content by a factor of ca. five. However, an increased amount of MS smoke ammonia does not increase the rate of nicotine loss from the particles. The combined results support the conclusion that ammonia in mainstream smoke has little effect, if any, upon the rate and amount of nicotine evaporation from MS smoke particles.
Chemical Research in Toxicology 09/2004; 17(8):1020-37. · 4.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A literature review is presented on the pyrolysis chemistry of mono-, di- and polysaccharides, with emphasis on d-glucose, d-fructose, sucrose and cellulose. A model, consisting of nine factors, is proposed to explain the pyrolysis product distributions observed. Product profiles depend on experimental conditions, particularly pyrolysis temperatures and residence times and the presence of other substances, e.g. acids, bases and salts. At higher temperatures, polynuclear aromatic hydrocarbons (PAHs) are the predominant condensed-phase products from carbohydrates. At lower temperatures, pyrolysis of pure cellulose generally favors 1,6-anhydro-β-d-glucopyranose (levoglucosan) formation as well as low molecular weight oxygenated products, e.g. glycolaldehyde. Cellulose pyrolysis also yields other products, including furans. Pyrolysis of d-glucose, d-fructose, and sucrose appears to favor furan production rather than anhydrosugars and low molecular weight carbonyl compounds. Furans distill rapidly from the pyrolysis zone rather than degrade. For reducing sugars, the ability to react from their acyclic isomers to form cyclic five-membered rings, i.e. furan precursors, may be a significant controlling factor. Multiple pathways to products are likely in all these pyrolyses. These pyrolysis studies provide parallels to mainstream (MS) cigarette smoke precursor–product relationships.
Journal of Analytical and Applied Pyrolysis 01/2003; · 3.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Curtin-Hammett (C-H) principle and the Winstein-Holness (W-H) equation approximate the product ratio and overall rate constant of reaction for systems involving a starting material which exists in two forms, each of which reacts via first-order kinetics to give a different product. The C-H/W-H approximations are valid when the rates of isomer interconversion are significantly faster than the rates of product formation. The present treatment encompasses non-first-order reactions to product. A numerical predictor-corrector technique is used to show (1) that relative reagent concentration can affect both the product ratio and the observed rates of product formation; (2) that the absolute concentration of reagent and substrate can affect the kinetics; and (3) that factors (1) and (2) above can affect the validity of the C-H/W-H approximations for non-first-order C-H/W-H schemes.