Smoke composition and predicting relationships for international commercial cigarettes smoked with three machine-smoking conditions

Mainstream smoke chemistry analysis of samples from the 2009 US cigarette market

A survey of selected mainstream smoke constituents from commercially marketed US cigarettes was conducted in 2009. The US cigarette market was segmented into thirteen (13) strata based on Cambridge Filter Method (CFM) "tar" category and cigarette design parameters. Menthol and non-menthol cigarettes were included. Sixty-one (61) cigarette brand styles were chosen to represent the market. Another thirty-four (34) brand styles of interest were included in the survey along with a Kentucky 3R4F reference cigarette. Twenty mainstream smoke constituents were evaluated using the Health Canada smoking regimen. By weighting the results of the 61 brand styles using the number of brand styles represented by each stratum, the mainstream smoke constituent means and medians of the US cigarette market were estimated. For nicotine, catechol, hydroquinone, benzo(a)pyrene and formaldehyde the mean yields increased with increasing "tar" yields. Constituent yields for the ultra-low "tar" and low "tar" cigarettes were not significantly different for most other analytes as ventilation blocking defeated any filter air dilution design features. In contrast, normalization per mg nicotine provided an inverse ranking of cigarette yields per CFM "tar" categories. Menthol cigarette mean constituent yields were observed to be within the range of the non-menthol cigarettes of similar "tar" categories.

Comparative computational modeling of airflows and vapor dosimetry in the respiratory tracts of rat, monkey, and human

Computational fluid dynamics (CFD) models are useful for predicting site-specific dosimetry of airborne materials in the respiratory tract and elucidating the importance of species differences in anatomy, physiology, and breathing patterns. We improved the imaging and model development methods to the point where CFD models for the rat, monkey, and human now encompass airways from the nose or mouth to the lung. A total of 1272, 2172, and 135 pulmonary airways representing 17±7, 19±9, or 9±2 airway generations were included in the rat, monkey and human models, respectively. A CFD/physiologically based pharmacokinetic model previously developed for acrolein was adapted for these anatomically correct extended airway models. Model parameters were obtained from the literature or measured directly. Airflow and acrolein uptake patterns were determined under steady-state inhalation conditions to provide direct comparisons with prior data and nasal-only simulations. Results confirmed that regional uptake was sensitive to airway geometry, airflow rates, acrolein concentrations, air:tissue partition coefficients, tissue thickness, and the maximum rate of metabolism. Nasal extraction efficiencies were predicted to be greatest in the rat, followed by the monkey, and then the human. For both nasal and oral breathing modes in humans, higher uptake rates were predicted for lower tracheobronchial tissues than either the rat or monkey. These extended airway models provide a unique foundation for comparing material transport and site-specific tissue uptake across a significantly greater range of conducting airways in the rat, monkey, and human than prior CFD models.

Comparative study of the main characteristics and composition of the mainstream smoke of ten cigarette brands sold in Spain

In this study 10 commercial top selling cigarette brands in Spain have been machine smoked and the mainstream smoke has been analyzed. Multifunctional analysis has been satisfactorily employed to correlate the effect of the main design features of the cigarettes including amount of tobacco, filter size or paper weight with the amount of smoked tobacco and with the ratio CO(2)/CO. The composition of the vapor phase and that of the particulate matter have been analyzed. The particulate matter retained in the filter of the cigarettes has also been analyzed showing a distinct behavior of the compounds condensed in the cigarette filters and in the traps, related to their retention time. A general trend for the relative yield of some compounds in the different brands have been identified and confirmed by multifunctional analysis. Nevertheless, there are some noticeable compounds that behave differently in the different brands.

Use of hazard indices for a theoretical evaluation of cigarette smoke composition

The chemical composition of cigarette mainstream smoke (MS) has been quantitatively analyzed in multiple studies, often with the objective to toxicologically evaluate and compare various types of MS. Increases and decreases in yields of constituents between MS types can only be consolidated if these yields are compared on the basis of toxicological properties of the individual constituents. For the risk assessment of various complex mixtures including MS, a hazard index (HI) approach has been used that requires weighing of the exposure to individual MS constituents by cancer and noncancer potency values. The objective of the current study is to review the past uses of the HI concept for MS and smokeless tobacco and discuss strengths and limitations of using this concept. Published information as well as information made available on the Web was used. The HI concept has been applied to MS for determining and comparing theoretical lifetime risks, for consumer communication, for the prioritization of constituents for reduction, for ingredient assessment, and for the selection of constituents for regulation. The limitations of this approach are associated with the limited number of MS constituents with available yield data, the gaps and uncertainties in available potency values, the application to relatively high exposure concentrations, and the default assumption of additivity. The derived theoretical noncancer index is dominated by acrolein to an extent that there seems to be not much advantage in using the HI concept for noncancer assessments. The derived theoretical cancer index is dominated by genotoxic carcinogens of the MS vapor phase and may thus complement currently used toxicological assays in a tiered evaluation approach. As is the case for every other assay and interpretation model, the HI concept needs to be applied with its limitations and weaknesses in mind. Its best application is for comparative purposes. It should be kept in mind that the HI concept is a theoretical concept and does not provide actual risk information.

Effects of smoking regimens and test material format on the cytotoxicity of mainstream cigarette smoke

The purpose of this study was to evaluate the effects of test material format and smoking regimens on comparative toxicity testing of cigarette smoke. Total particulate matter (TPM) or whole smoke (WS) generated from three test cigarettes under International Organization for Standardization (ISO) or Health Canada Intensive (HCI) regimens were assessed for cytotoxicity using the neutral red uptake (NRU) cytotoxicity assay. Under both ISO and HCI regimens, the relative differences of cytotoxicity among the test cigarettes indicated by the EC50 values in WS were significantly higher than those in TPM. For TPM testing, cytotoxicity was decreased going from ISO regimen to HCI regimen, consistent with the reported reductions of toxicant output on a per unit of TPM basis under the HCI regimen. For WS, cytotoxicity increased for the two lower TPM cigarettes, and decreased for the higher TPM cigarette going from HCI regimen to ISO regimen. Results from this study demonstrated WS should be the preferable test material format for smoke toxicity testing whenever possible. Intensive smoking regimens, such as HCI, are less likely to underestimate smoke toxicant intakes by smokers, and should be included in the comparative toxicological testing strategy.

Scientific assessment of the use of sugars as cigarette tobacco ingredients: a review of published and other publicly available studies

Sugars, such as sucrose or invert sugar, have been used as tobacco ingredients in American-blend cigarettes to replenish the sugars lost during curing of the Burley component of the blended tobacco in order to maintain a balanced flavor. Chemical-analytical studies of the mainstream smoke of research cigarettes with various sugar application levels revealed that most of the smoke constituents determined did not show any sugar-related changes in yields (per mg nicotine), while ten constituents were found to either increase (formaldehyde, acrolein, 2-butanone, isoprene, benzene, toluene, benzo[k]fluoranthene) or decrease (4-aminobiphenyl, N-nitrosodimethylamine, N-nitrosonornicotine) in a statistically significant manner with increasing sugar application levels. Such constituent yields were modeled into constituent uptake distributions using simulations of nicotine uptake distributions generated on the basis of published nicotine biomonitoring data, which were multiplied by the constituent/nicotine ratios determined in the current analysis. These simulations revealed extensive overlaps for the constituent uptake distributions with and without sugar application. Moreover, the differences in smoke composition did not lead to relevant changes in the activity in in vitro or in vivo assays. The potential impact of using sugars as tobacco ingredients was further assessed in an indirect manner by comparing published data from markets with predominantly American-blend or Virginia-type (no added sugars) cigarettes. No relevant difference was found between these markets for smoking prevalence, intensity, some markers of dependence, nicotine uptake, or mortality from smoking-related lung cancer and chronic obstructive pulmonary disease. In conclusion, thorough examination of the data available suggests that the use of sugars as ingredients in cigarette tobacco does not increase the inherent risk and harm of cigarette smoking.

Design and chemical evaluation of reduced machine-yield cigarettes

Experimental cigarettes (ECs) were made by combining technological applications that individually reduce the machine measured yields of specific toxicants or groups of toxicants in mainstream smoke (MS). Two tobacco blends, featuring a tobacco substitute sheet or a tobacco blend treatment, were combined with filters containing an amine functionalised resin (CR20L) and/or a polymer-derived, high activity carbon adsorbent to generate three ECs with the potential for generating lower smoke toxicant yields than conventional cigarettes. MS yields of smoke constituents were determined under 4 different smoking machine conditions. Health Canada Intense (HCI) machine smoking conditions gave the highest MS yields for nicotine-free dry particulate matter and for most smoke constituents measured. Toxicant yields from the ECs were compared with those from two commercial comparator cigarettes, three scientific control cigarettes measured contemporaneously and with published data on 120 commercial cigarettes. The ECs were found to generate some of the lowest machine yields of toxicants from cigarettes for which published HCI smoke chemistry data are available; these comparisons therefore confirm that ECs with reduced MS machine toxicant yields compared to commercial cigarettes can be produced. The results encourage further work examining human exposure to toxicants from these cigarettes, including human biomarker studies.

Toxic elements in tobacco and in cigarette smoke: inflammation and sensitization

Biochemically and pathologically, there is strong evidence for both atopic and nonatopic airway sensitization, hyperresponsiveness, and inflammation as a consequence of exposure to tobacco mainstream or sidestream smoke particulate. There is growing evidence for the relation between exposure to mainstream and sidestream smoke and diseases resulting from reactive oxidant challenge and inflammation directly as a consequence of the combined activity of neutrophils, macrophages, dendritic cells, eosinophils, basophils, as a humoral immunological consequence of sensitization, and that the metal components of the particulate play a role in adjuvant effects. As an end consequence, carcinogenicity is a known outcome of chronic inflammation. Smokeless tobacco has been evaluated by the IARC as a group 1 carcinogen. Of the many harmful constituents in smokeless tobacco, oral tissue metallothionein gradients suggest that metals contribute to the toxicity from smokeless tobacco use and possibly sensitization. This work reviews and examines work on probable contributions of toxic metals from tobacco and smoke to pathology observed as a consequence of smoking and the use of smokeless tobacco.

A novel application of the Margin of Exposure approach: segregation of tobacco smoke toxicants

This paper presents a rationale for utilising a Margin of Exposure (MOE) approach to the segregation of tobacco smoke toxicants for risk assessment and management purposes. Future regulatory frameworks and product modifications aimed at tobacco harm reduction could utilise data that segregate toxicants using associations with specific diseases caused by cigarette smoking together with an indication of their relative contribution to that disease. Compounds with MOEs >10,000 accompanied by appropriate narrative are considered "low priority for risk management actions". This paper applies the MOE model to representative examples of tobacco smoke toxicants associated with respiratory tract carcinogenesis and other respiratory diseases. A multiplicity of published dose response data on individual toxicants has been used to determine the range of possible MOE values, thus demonstrating the consistency of the relationships. Acetaldehyde, acrolein, acrylonitrile, cadmium, ethylene oxide, formaldehyde and isoprene all segregate with MOEs <10,000 and should be considered as high priority for exposure reduction research whereas benzo(a)pyrene and vinyl chloride segregate with an MOE >10,000 and therefore may be considered as a low priority. 1,3-Butadiene, m-/p-cresols, NNK and NNN are assumed to segregate with high priority although additional data would be required to complete a full MOE assessment.

A review of current smoke constituent measurement activities and aspects of yield variability

An increasing number of initiatives to regulate cigarette smoke constituents beyond 'tar', nicotine and carbon monoxide are being launched. The objective of existing and proposed regulation is presumably either to gain a better understanding of product performance, to be able to discriminate between products, or to impose limits for selected constituents. However, without standardized analytical methods and measurement tolerances a meaningful comparison of data or verification against regulated limits is challenging if not impossible. Hence, an understanding of the validity and limitations of generated data is important for industry and regulators alike to avoid unjustified 'out-of-compliance' situations, and consequent competitive and reputational concerns for manufacturers. This paper reviews smoke constituent regulation and provides examples of technical challenges and good practice. It discusses approaches used to standardize measurements; the role of the International Organization for Standardization; factors influencing result variability and limitations and possible misinterpretations of generated data. If smoke constituents regulation is to be introduced, a standardized, science-based approach must be the pre-requisite for the generation and comparison of data. Potential analytical and technical issues must be resolved in discussion, both before and after the implementation of regulation, to the benefit of the public, regulators and manufacturers.

The use of a novel tobacco-substitute sheet and smoke dilution to reduce toxicant yields in cigarette smoke

The Institute of Medicine encouraged the pursuit and development of potential reduced-exposure products, tobacco products that substantially reduce exposure to one or more tobacco toxicants and can reasonably be expected to reduce the risk of one or more specific diseases or other adverse health effects. One approach to reducing smoke toxicant yields is to dilute the smoke with glycerol. We report chemical, biological and human exposure data related to experimental cigarettes containing up to 60% of a novel glycerol containing "tobacco-substitute" sheet. Analysis of mainstream smoke from experimental cigarettes showed reductions in yields of most measured constituents, other than some volatile species. In vitro toxicological tests showed reductions in the activity of smoke particulates in proportion to their glycerol content. Human exposure to nicotine was reduced by a mean of 18% as determined by filter studies and by 14% using 24h urinary biomarker analysis. Smoke particulate exposures were reduced by a mean of 29% in filter studies and NNK exposure by similar amounts based on urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol concentrations. These results show that reducing exposure to some smoke toxicants is possible using a tobacco-substitute sheet, although some smoke toxicants, and the sensory attributes of the smoke, remain as technical challenges.

Insights from a multi-year program designed to test the impact of ingredients on mainstream cigarette smoke toxicity

CONTEXT

Cigarette tobacco ingredients may alter the distribution of chemical constituents present in smoke. When considering the toxicological relevance of potential ingredient-related effects on chemical and biological measurements assessing cigarette smoke toxicity, it is critical to understand the intrinsic variability of tobacco and cigarette smoke that is influenced by the environmental conditions during growing, agricultural practices during preparation, cigarette manufacturing tolerances, and stability of the assay methods.

OBJECTIVE

To understand possible effects of ingredients on cigarette smoke toxicity, various chemical and biological endpoints were measured in smoke from experimental cigarettes (added ingredient) to the intrinsic variability of control cigarettes (no added ingredient).

MATERIALS AND METHODS

Data were collected during a multi-year program testing a variety of cigarette ingredients from several chemical classes. Chemical analysis of mainstream cigarette smoke,and biological procedures (Salmonella mutagenicity, cytotoxicity, and smoke inhalation) were performed using validated and controlled laboratory methods. The within-study and temporal variation of control cigarettes manufactured in parallel with experimental cigarettes was calculated and used to measure intrinsic variability.

RESULTS

The overwhelming majority of data generated from experimental cigarettes fell within the experiment variability represented by the pooled standard error of the entire multi-year dataset for the control cigarettes.

CONCLUSION

The results of this evaluation add to a growing body of the literature regarding a weight of evidence assessment of cigarette ingredient toxicity. When assessed against the variability of assay methodology, natural agricultural change, and manufacturing control, the ingredients studied here demonstrated little relevant influence on the mainstream cigarette smoke toxicity endpoints measured.

Reduction of aldehydes and hydrogen cyanide yields in mainstream cigarette smoke using an amine functionalised ion exchange resin

BACKGROUND

Cigarette smoking is a well recognized cause of diseases such as lung cancer, chronic obstructive pulmonary disease and cardiovascular disease. Of the more than 5000 identified species in cigarette smoke, at least 150 have toxicological activity. For example, formaldehyde and acetaldehyde have been assigned as Group 1 and Group 2B carcinogens by IARC, and hydrogen cyanide has been identified as a respiratory and cardiovascular toxicant. Active carbon has been shown to be an effective material for the physical adsorption of many of the smoke volatile species. However, physical adsorption of acetaldehyde, formaldehyde and also hydrogen cyanide from smoke is less effective using carbon. Alternative methods for the removal of these species from cigarette smoke are therefore of interest. A macroporous, polystyrene based ion-exchange resin (Diaion®CR20) with surface amine group functionality has been investigated for its ability to react with aldehydes and HCN in an aerosol stream, and thus selectively reduce the yields of these compounds (in particular formaldehyde) in mainstream cigarette smoke.

RESULTS

Resin surface chemistry was characterized using vapour sorption, XPS, TOF-SIMS and 15N NMR. Diaion®CR20 was found to have structural characteristics indicating weak physisorption properties, but sufficient surface functionalities to selectively remove aldehydes and HCN from cigarette smoke. Using 60 mg of Diaion®CR20 in a cigarette cavity filter gave reductions in smoke formaldehyde greater than 50% (estimated to be equivalent to >80% of the formaldehyde present in the smoke vapour phase) independent of a range of flow rates. Substantial removal of HCN (>80%) and acetaldehyde (>60%) was also observed. The performance of Diaion®CR20 was found to be consistent over a test period of 6 months. The overall adsorption for the majority of smoke compounds measured appeared to follow a pseudo-first order approximation to second order kinetics.

CONCLUSIONS

This study has shown that Diaion®CR20 is a highly selective and efficient adsorbent for formaldehyde, acetaldehyde and HCN in cigarette smoke. The reductions for these compounds were greater than those achieved using an active carbon. The results also demonstrate that chemisorption can be an effective mechanism for the removal of certain vapour phase toxicants from cigarette smoke.

Evaluation of two derivatization reagents for the determination by LC-MS/MS of ammonia in cigarette mainstream smoke

Ammonia in cigarette mainstream smoke was quantified by LC-MS/MS after derivatization. Two different reagents, fluorescamine and dansyl chloride, were investigated, but only the latter gave stable derivatives; therefore, it was considered the most appropriate choice. Smoke samples were collected on a Cambridge filter pad followed by an impinger containing a solution of hydrochloric acid. Ammonia was then derivatized with a 18.5 mM solution of dansyl chloride in acetonitrile at 70 °C for 30 min in a vial with the internal standard, (15)ND(4)Cl. The resulting derivative was analyzed by LC-MS/MS detection with an atmospheric pressure chemical ionization (APCI) interface in the positive ionization mode using multiple-reaction monitoring (MRM). Good linearity was obtained in the concentration range of 0.02-1.65 μg/mL (r(2) ≥ 0.999), and the limit of detection (LOD) was established at 0.006 μg/mL. This method has the advantage of being sensitive, efficient, and reliable and is not hindered by interferences from the sample matrix. It should thus be considered a reference method of choice for the determination of ammonia in smoke.

Comparison of the physiological and morphological effects of cigarette smoke exposure at comparable weekly doses on Sprague-Dawley rats

A variety of dose x duration exposure regimens have been used in inhalation toxicity studies using rodents. We evaluated the effects of differences in smoke concentration and daily exposure duration under similar weekly cumulative exposures in rats to determine potential variation in type and severity of adverse effects in 13-week exposure studies. The weekly cumulative dosages were 2100 and 4200 μg wet total particle matter (WTPM)/L, and the daily exposure durations were 1 and 6 h. Weekly exposure duration was 5 or 7 days/week for groups exposed 1 h/day and 7 days/week for groups exposed 6 h/day. Recovery duration was 6 and 13 weeks. Mainstream smoke exposure suppressed body weight (BW) gain in both regimens. Lower dose groups exposed 1 h/day had a consistently greater of BW gain compared with corresponding 6 h/day groups. Respiratory rate, tidal volume, and minute volume (MV) were suppressed in a dose-dependent manner in both regimens. Higher MV in rats exposed for 6 h/day compared with rats exposed 1 h/day suggested that a lower concentration for longer duration resulted in a greater total inhaled mass (TIM) in rats exposed 6 h/day. Groups exposed for 6 h/day had lower blood carboxyhemoglobin and plasma nicotine levels than groups exposed 1 h/day, reflecting the lower carbon monoxide (CO) and WTPM concentrations in the 6 h/day groups. Data from examination of bronchoalveolar lavage fluids (BALF) and respiratory tract tissues indicated comparable effects between both regimens. Exposure-induced histopathological changes regressed similarly for both regimens after the recovery periods.

Cytotoxicity of eight cigarette smoke condensates in three test systems: comparisons between assays and condensates

Cytotoxic properties of tobacco smoke are associated with chronic tobacco-related diseases. The cytotoxicity of tobacco smoke can be tested with short-term predictive assays. In this study, we compare eight mainstream cigarette smoke condensates (CSCs) from commercial and experimental cigarettes in three different cytotoxicity assays with unique and overlapping endpoints. The CSCs demonstrated cytotoxicity in all assays. In the multiple cytotoxicity endpoint (MCE) assay with TK-6 cells, the cigarette varieties that had the highest EC50s for reduced cell growth also showed a positive dose-response relationship for necrotic cells. In the IdMOC multiple cell-type co-culture (MCTCC) system, all CSCs reduced the viability of the cells. Low concentrations of some CSCs had a stimulatory effect in lung microvascular endothelial cells and small airway epithelial cells. In the neutral dye assay (NDA), except for a 100% flue-cured tobacco CSC, there was little consistency between CSCs producing morphological evidence of moderate or greater toxicity and the CSCs with the lowest EC50s in the MCE or MCTCC assays. Overall, cigarettes made with flue-cured tobacco were the most cytotoxic across the assays. When results were expressed on a per-mg of nicotine basis, lower tar cigarettes were the most cytotoxic in primary human respiratory cells.

Some consequences of using cigarette machine smoking regimes with different intensities on smoke yields and their variability

When smoking cigarettes under an intense regime with a combination of 100% ventilation blocking and high flow rates, as currently mandated by Health Canada, significant increases in filter temperatures and disproportionately high levels of mainstream smoke water and moisture accumulating in the spent filter were found when compared to other smoking regimes, especially for highly filter ventilated cigarettes. These effects have been reported to decrease cigarette firmness during the course of smoking, to alter filtration properties and efficiencies and to confound the measurement of particulate matter. The high filter temperatures generated also lead to significant amounts of vapour phase compounds desorbing from carbon filters and an over-estimation of the yields of these components. Less adsorption on or more desorption from carbon filters was found for compounds with the highest volatility. Therefore, yield data from the intense regime may not reflect the effectiveness of cigarette design features to reduce certain smoke components that occurs when products are smoked under conditions closer to those used by the majority of smokers in real world situations. In addition, a combination of these interacting factors may explain the worse level of between-laboratory reproducibility data for particulate matter measurement obtained during intense machine smoking. Among-laboratory data variability for vapour phase components, other than carbon monoxide, and for particulate phase components, other than nicotine, still needs to be evaluated in collaborative studies. Before proposing smoking regimes as tools to evaluate smoke emissions, it is essential to understand these various interacting factors and subsequent uncontrolled effects that such regimes can generate and the limitations of their use. These observations imply that higher tolerances may need to be set and taken into account when smoking under the intense regime before deciding that, for a given product, there are real differences between the yields determined in different laboratories.

Cigarettes sold in China: design, emissions and metals

BACKGROUND

China is the home to the world's largest cigarette maker, China National Tobacco Company (CNTC), yet little is known publicly about the design and emissions of Chinese cigarettes. CNTC is currently in the process of consolidating its brands and has ambitions to export its cigarettes. Machine-measured tar yields of many of its cigarette brands have also been reduced, similar to what occurred in Western countries from the 1970s through the 1990s with so-called 'low-tar' cigarettes introduced to address consumer concerns about health risks from smoking.

METHOD

The current study examines the design and physical characteristics, labelled smoke emissions and tobacco metals content of leading brands of Chinese cigarettes from seven cities purchased in 2005-6 and in 2007.

RESULTS

Findings suggest that similar to most countries, tar levels of Chinese cigarettes are predicted primarily by tobacco weight and filter ventilation. Ventilation explained approximately 50% of variation observed in tar and 60% variation in carbon monoxide yields. We found little significant change in key design features of cigarettes purchased in both rounds. We observed significant levels of various metals, averaging 0.82 μg/g arsenic (range 0.3-3.3), 3.21 μg/g cadmium (range 2.0-5.4) and 2.65 μg/g lead (range 1.2-6.5) in a subsample of 13 brands in 2005-6, substantially higher than contemporary Canadian products.

CONCLUSION

Results suggest that cigarettes in China increasingly resemble those sold in Western countries, but with tobacco containing higher levels of heavy metals. As CNTC looks to export its product around the world, independent surveillance of tobacco product characteristics, including tobacco blend characteristics, will become increasingly important.

Free-base nicotine in tobacco products. Part I. Determination of free-base nicotine in the particulate phase of mainstream cigarette smoke and the relevance of these findings to product design parameters

The free-base nicotine (FBN) content of mainstream cigarette smoke (MSS) has been discussed in the peer-reviewed literature and popular press. It has been alleged that manufacturers adjust product design features to increase the percentage of total nicotine (TN) in the MSS gas-vapor phase that is unprotonated [P(g)(,nic)(%)] and/or the fraction of nicotine in the MSS total particulate matter (TPM) that is unprotonated (FBN/TN). Our research showed the Health Canada Intensive smoking conditions negated the effects of blend and cigarette design features reported to raise the pH of TPM collected under ISO or US FTC conditions. Our research also showed that when additive-free Canadian cigarettes were smoked under ISO conditions, the FBN/TN ratio increased as the tar/nicotine ratio decreased. Our findings are in line with other studies that have questioned allegations of a relationship between use of ammonia and its compounds as tobacco additives and amounts of unprotonated nicotine in MSS. In addition, the experimental work demonstrated how use of solid-phase microextraction to estimate FBN can yield erroneously high results due to improper conditioning and/or smoking of the cigarettes. Our research showed that there is no longer any scientific support for regulators to require smoke pH and FBN determinations on cigarette products.

In vitro micronucleus assay for cigarette smoke using a whole smoke exposure system: a comparison of smoking regimens

Previous studies on the biological assessment of cigarette smoke (CS) mainly focused on the total particulate matter (TPM) collected using a Cambridge filter or gas vapor phase (GVP) bubbled through phosphate-buffered saline (PBS). To study the effects of native CS in vitro, direct exposure methods have been developed. Meanwhile, in vitro micronucleus (MN) assays have been reported to evaluate the mutagenicity of CS. The objective of this research is to investigate the MN-inducing activity of whole smoke (WS) and GVP using a whole smoke exposure system, CULTEX((R)), which allows direct exposure of cultured cells to native CS at the air/liquid interface (ALI). CS was generated according to the International Organization for Standardization (ISO; 35ml, 2s, once per 60s) or the Health Canada Intensive (HCI; 55ml, 2s, once per 30s, with complete ventilation block) regimens and Chinese hamster lung (CHL/IU) cells were then exposed to this smoke. Dosages were adjusted according to the amount of smoke entering the actual exposure position. Under both smoking regimens, WS and GVP from 2R4F reference cigarettes induced MN responses. The concept of the dosage and similar dose-response relationships between theoretical and monitored dosage values under the two regimens enabled us to compare the MN-inducing activities of cigarettes in the direct exposure assay, even in the case of various experimental settings or different TPM amounts. MN-inducing activities of 2R4F under the ISO regimen seemed to be higher than those under HCI estimated by the TPM equivalent calculated values.

Machine-smoking studies of cigarette filter color to estimate tar yield by visual assessment and through the use of a colorimeter

This paper explores using the intensity of the stain on the end of the filter ("filter color") as a vehicle for estimating cigarette tar yield, both by instrument reading of the filter color and by visual comparison to a template. The correlation of machine-measured tar yield to filter color measured with a colorimeter was reasonably strong and was relatively unaffected by different puff volumes or different tobacco moistures. However, the correlation of filter color to machine-measured nicotine yield was affected by the moisture content of the cigarette. Filter color, as measured by a colorimeter, was generally comparable to filter extraction of either nicotine or solanesol in its correlation to machine-smoked tar yields. It was found that the color of the tar stain changes over time. Panelists could generally correctly order the filters from machine-smoked cigarettes by tar yield using the intensity of the tar stain. However, there was considerable variation in the panelist-to-panelist tar yield estimates. The wide person-to-person variation in tar yield estimates, and other factors discussed in the text could severely limit the usefulness and practicality of this approach for visually estimating the tar yield of machine-smoked cigarettes.

New insights into the formation of volatile compounds in mainstream cigarette smoke

A sampling system has been set up to monitor a group of volatile smoke analytes (nitric oxide, acetaldehyde, acetone, benzene, toluene, 1,3 butadiene, isoprene and carbon dioxide) from mainstream cigarette smoke on a puff-resolved basis. The system was able to record gas evolution profiles during puffing and interpuff periods without interruption (e.g. taking clearing puffs). Gas phase smoke analytes were sampled as close to the mouth end of the cigarette filter as possible in order to minimise any dead volume effect. The results revealed that, for some volatile species, a significant fraction (e.g. up to 30% for benzene) in the cigarette mainstream smoke had been generated during the preceding smoulder period. These species were trapped or absorbed within the cigarette rod and then subsequently eluted during the puff. The identification of the two sources of the mainstream smoke, a smouldering source and a puffing source, has not been reported before. The observation contributes to the fundamental knowledge of the cigarette smoke formation and may have implications on wider smoke chemistry and associated effects.

Upper airways sensory irritation responses of mice exposed to mainstream smoke from four cigarette types

Relative sensory irritation responses for Swiss-Webster mice exposed nose-only to mainstream tobacco smoke were evaluated for several cigarette types using a smoking regimen consisting of a 35-ml puff, 2 s in duration, taken once per minute. The degree of sensory irritation for each cigarette type was evaluated as the smoke concentration inducing a 50% reduction in breathing frequency. The smoke concentration inducing 50% respiratory depression is called the RD(50) value. Study findings suggest that mainstream tobacco smoke from the Eclipse cigarette, which primarily heats rather than burns tobacco, yielded an RD(50) that was significantly higher (approximately twofold) than a tobacco-burning leading ultralight or the 2R4F or 1R5F reference cigarettes. This is indicative of reduced upper airways irritation by Eclipse that may be due to its distinct design. Study findings suggest that the irritating nature of mainstream tobacco smoke from different cigarette types can be evaluated effectively in terms of smoke concentration using the relative sensory irritation assessment. These findings constitute the first report about use of the RD(50) sensory irritation response during comparative evaluations of mainstream tobacco smoke.

Effects of 10 cigarette smoke condensates on primary human airway epithelial cells by comparative gene and cytokine expression studies

Cigarettes vary in tobacco blend, filter ventilation, additives, and other physical and chemical properties, but little is known regarding potential differences in toxicity to a smoker's airway epithelia. We compared changes in gene expression and cytokine production in primary normal human bronchial epithelial cells following treatment for 18 h with cigarette smoke condensates (CSCs) prepared from five commercial and four research cigarettes, at doses of approximately 4 microg/ml nicotine. Nine of the CSCs were produced under a standard International Organization for Standardization smoking machine regimen and one was produced by a more intense smoking machine regimen. Isolated messenger RNA (mRNA) was analyzed by microarray hybridization, and media was analyzed for secreted cytokines and chemokines. Twenty-one genes were differentially expressed by at least 9 of the 10 CSCs by more than twofold, including genes encoding detoxifying and antioxidant proteins. Cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) and NAD(P)H dehydrogenase, quinone 1 (NQO-1) were selected for validation with quantitative real-time PCR (qRT-PCR) and Western blot analyses. NQO-1 expression determined with microarrays, qRT-PCR, and Western blotting differed among the CSC types, with good correlation among the different assays. CYP1A1 mRNA levels varied substantially, but there was little correlation with the protein levels. For each CSC, the three most induced and three most repressed genes were identified. These genes may be useful as markers of exposure to that particular cigarette type. Furthermore, differences in interleukin-8 secretion were observed. These studies lay the foundation for future investigations to analyze differences in the responses of in vivo systems to tobacco products marketed with claims of reduced exposure or reduced harm.

Reconciling human smoking behavior and machine smoking patterns: implications for understanding smoking behavior and the impact on laboratory studies

BACKGROUND

Recent Food and Drug Administration legislation enables the mandating of product performance standards for cigarette smoke and the evaluation of manufacturers' health claims for modified tobacco products. Laboratory studies used for these evaluations and also for understanding tobacco smoke toxicology use machines to generate smoke. The goal of this review is to critically evaluate methods to assess human smoking behavior and replicate this in the laboratory.

METHODS

Smoking behavior and smoking machine studies were identified using PubMed and publicly available databases for internal tobacco company documents.

RESULTS

The smoking machine was developed to generate smoke to allow for comparing cigarette tar and nicotine yields. The intent was to infer relative human disease risk, but this concept was flawed because humans tailor their smoking to the product, and chemical yields and toxicologic effects change with different smoking profiles. Although smoking machines also allow for mechanistic assessments of smoking-related diseases, the interpretations also are limited. However, available methods to assess how humans puff could be used to provide better laboratory assessments, but these need to be validated. Separately, the contribution of smoke mouth-holding and inhalation to dose need to be assessed, because these parts of smoking are not captured by the smoking machine. Better comparisons of cigarettes might be done by tailoring human puff profiles to the product based on human studies and comparing results across regimens.

CONCLUSIONS

There are major research gaps that limit the use of smoking machine studies for informing tobacco control regulation and mechanistic studies.

Cytotoxicity, mutagenicity, and tumorigenicity of mainstream smoke from three reference cigarettes machine-smoked to the same yields of total particulate matter per cigarette

The particle phase of mainstream smoke from three types of cigarettes was investigated in vitro in the Neutral Red cytotoxicity assay and the Salmonella typhimurium Reverse Mutation Assay (Ames Assay) and in vivo in the two-stage dermal tumorigenicity assay (Skin Painting Assay) in SENCAR mice. The cigarettes used were the Reference Cigarettes 1R5F, 2R4F, and 2R1F from the University of Kentucky, USA, which, when smoked according to the smoking regimen defined by the International Standards Organization (ISO), produce a yield of approximately 2, 12, and 26 mg total particulate matter (TPM)/cigarette, respectively. All cigarettes were machine smoked according to ISO and then again in such a way that the TPM yields per cigarette equaled the ISO TPM yields of the other two cigarette types. The TPM from cigarettes with inherently different smoke yields showed similar in vitro toxicity and in vivo toxicity when, with different smoking regimens, these cigarettes were smoked to the same TPM yield. More intensive smoking conditions were associated with lower in vitro and in vivo activity per gram of TPM. The strongest decrease, and the tightest correlation, in this regard was observed for dermal tumorigenicity (tumor incidence).

gammaH2AX: A potential DNA damage response biomarker for assessing toxicological risk of tobacco products

Differentiation among American cigarettes relies primarily on the use of proprietary tobacco blends, menthol, tobacco substitutes, paper porosity, paper additives, and filter ventilation. These characteristics substantially alter per cigarette yields of tar and nicotine in standardized protocols promulgated by government agencies. However, due to compensatory alterations in smoking behavior to sustain a preferred nicotine dose (e.g., by increasing puff frequency, inhaling more deeply, smoking more cigarettes per day, or blocking filter ventilation holes), smokers actually inhale similar amounts of tar and nicotine regardless of any cigarette variable, supporting epidemiological evidence that all brands have comparable disease risk. Consequently, it would be advantageous to develop assays that realistically compare cigarette smoke (CS)-induced genotoxicity regardless of differences in cigarette construction or smoking behavior. One significant indicator of potentially carcinogenic DNA damage is double strand breaks (DSBs), which can be monitored by measuring Ser 139 phosphorylation on histone H2AX. Previously we showed that phosphorylation of H2AX (defined as gammaH2AX) in exposed lung cells is proportional to CS dose. Thus, we proposed that gammaH2AX may be a viable biomarker for evaluating genotoxic risk of cigarettes in relation to actual nicotine/tar delivery. Here we tested this hypothesis by measuring gammaH2AX levels in A549 human lung cells exposed to CS from a range of commercial cigarettes using various smoking regimens. Results show that gammaH2AX induction, a critical event of the mammalian DNA damage response, provides an assessment of CS-induced DNA damage independent of smoking topography or cigarette type. We conclude that gammaH2AX induction shows promise as a genotoxic bioassay offering specific advantages over the traditional assays for the evaluation of conventional and nonconventional tobacco products.

Effect of filtration by activated charcoal on the toxicological activity of cigarette mainstream smoke from experimental cigarettes

Activated charcoal (AC) filtration reportedly decreases the yields of smoke vapor phase constituents including some identified as human carcinogens and respiratory irritants. Non-clinical studies including chemical smoke analysis, in vitro cytotoxicity and mutagenicity (bacterial and mammalian cells), and in vivo subchronic rat inhalation studies were carried out using machine smoking at ISO conditions with lit-end research cigarettes containing AC filters. The objective was to assess whether AC filter technology would alter the established toxicity profile of mainstream smoke by increasing or decreasing any known toxicological properties, or elicit new ones. The reduced yield of vapor phase irritants from AC filter cigarettes correlated with markedly decreased in vitro cytotoxicity and in vivo morphology of the nose and lower respiratory tract. Increased yields of particulate phase constituents (e.g. polycyclic aromatic hydrocarbons) in AC filtered smoke were noted in comparison to controls in some studies. The in vitro bacterial mutagenicity of AC filtered smoke particulate preparations was occasionally increased over control levels. Laryngeal epithelial thickness was increased in some rats inhaling AC filtered smoke in comparison to controls, an effect perhaps related to higher inspiratory flow. When tested under more intense Massachusetts Department of Public Health smoking conditions, AC filter associated reductions in vapor phase constituent yields were smaller than those seen with ISO conditions, but the effect on in vitro cytotoxicity remained.

Rapid and sensitive method for simultaneous determination of six carcinogenic aromatic amines in mainstream cigarette smoke by liquid chromatography/electrospray ionization tandem mass spectrometry

Aromatic amines are one of the sources of carcinogenicity in cigarette and tobacco smoke. Accurate quantification of these chemicals is needed to assess public health risk. A new validated rapid, sensitive and analyte specific liquid chromatography/electrospray ionization tandem mass spectrometric (LC/MS/MS) method has been developed for the simultaneous determination of six aromatic amines in mainstream cigarette smoke using research reference cigarette 2R4F. Three popular Indian brand cigarettes were also analyzed using the same procedure. The limit of detection of this method ranged from 0.04 to 0.59 ng/cig using an injection volume of 7 microl. The identification of each amine was established by chromatographic retention times, analyte specific fragmentation pattern and relative peak area ratios of two product/precursor ion pairs. The method showed excellent reproducibility and was also rapid, selective and robust for aromatic amine determination from cigarette smoke.

Carbon-centered radicals in cigarette smoke: acyl and alkylaminocarbonyl radicals

The widely accepted mechanism of formation for carbon-centered radicals in the gas-phase cigarette smoke involves reactions of NO(2) and alkadienes. However, specific examples of such radicals have never been isolated from fresh cigarette smoke or their structure determined. We have identified two previously unrecognized classes of carbon-centered radicals, alkylaminocarbonyl and acyl radicals, that are unrelated to radicals that form by NO(x) chemistry. The combined abundance of these mainstream smoke radicals is significantly higher than the alkyl radicals previously quantified by electron paramagnetic resonance (EPR) solution spin-trapping methods. The new radicals were trapped directly from smoke with either 3-amino-proxyl (3AP) or 3-cyano-proxyl radical on a solid support and identified by combination of chemical synthesis, deuterium labeling, high-resolution mass spectrometry, nuclear magnetic resonance (NMR) spectroscopy, and ab initio quantum mechanical calculations. 3AP-R adducts were quantified both by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and by high-performance liquid chromatography with fluorescence detection (HPLC/FLD). Seven acyl and 11 alkylaminocarbonyl radicals were identified in the whole smoke of cigarettes made from single tobacco varieties and blended tobacco research cigarettes. The overall yield of these radicals was measured to be 168-245 nmol/cigarette from machine-smoked cigarettes under Federal Trade Commission (FTC) conditions. The yield was significantly reduced when the gas-phase smoke was separated from whole smoke by filtration through a 0.1 microm Cambridge filter pad or upon aging whole smoke in an inert tube.

Nicotine content and delivery across tobacco products

Nicotine is the principal alkaloid in both commercial and homemade products (e.g., cigarettes, smokeless tobacco, bidis, waterpipes) followed by nornicotine, anabasine, anatabine, and many other basic substances that contain a cyclic nitrogenous nucleus. Tobacco types, leaf position on the plant, agricultural practices, fertilizer treatment, and degree of ripening are among some prominent factors that determine the levels of alkaloids in tobacco leaf. From a random examination of 152 cultivated varieties of Nicotiana tabacum, a range of alkaloid variation between 0.17 and 4.93% was determined. In fact, every step in tobacco production that affects plant metabolism will influence the level of alkaloid content to a certain degree. Depending on blending recipe, type and amount of additives, and product design, all types of tobacco products contain a very wide range of nicotine concentration. However, the ultimate emission of nicotine to the user, exposure, and psychophar-macological effects depend not only on the content and emission, but also on the relationship between the product and the user.

Levels of tobacco-specific nitrosamines and polycyclic aromatic hydrocarbons in mainstream smoke from different tobacco varieties

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.

Toxicological Comparisons of Cigarettes Containing Different Amounts of Vanillin

Vanillin is a flavoring agent used in cigarettes. Previous toxicological examinations of the effects on the addition of vanillin to tobacco used mixtures with several other flavoring agents. In the present work, toxicological comparisons were made of experimental cigarettes containing no added vanillin against otherwise similar cigarettes with three different amounts of vanillin added to the tobacco. The main toxicological comparison was a subchronic inhalation study with mainstream smoke in Sprague-Dawley rats (exposures of 150 mg/m3 of total particulate matter, 6 h exposure per day, for 90 consecutive days). Vanillin concentrations in the tobacco of the 4 cigarette types at the end of the study were 0, 67, 1233, and 3109 ppm. Additional studies with mainstream smoke were Salmonella mutagenicity (5 bacterial strains, both with and without metabolic activation, particulate phase only), cytotoxicity of both particulate and gas/vapor phases (using the neutral red uptake assay), and analytical chemistry (49 analytes, including 5 metals). Similar responses were seen across the four cigarette types, and the responses were similar to those previously described in the scientific literature. At the same smoke concentration, the inhalation exposures produced effectively the same responses, in each of the four groups. Most of the changes produced in the 90 days of exposure were resolved in a 42-day postinhalation period. The addition of vanillin to tobacco at inclusion rates up to 3109 ppm did not influence a broad range of toxicological endpoints.

The possible role of ammonia toxicity on the exposure, deposition, retention, and the bioavailability of nicotine during smoking

A complete and rigorous review is presented of the possible effect(s) of ammonia on the exposure, deposition and retention of nicotine during smoking and the bioavailability of nicotine to the smoker. There are no toxicological data in humans regarding ammonia exposure within the context of tobacco smoke. Extrapolation from occupational exposure of ammonia to smoking in humans suggests minimal, non-toxicological effects, if any. No direct study has examined the effect of the ammonia on the total rate or amount of nicotine reaching the arterial bloodstream or brains of smokers. Machine-smoking methods have been reported which accurately quantify >99% of the nicotine in mainstream (MS) smoke for a wide variety of commercial and test cigarettes, including a series of experimental cigarettes having a range in MS smoke ammonia yields using the US Federal Trade Commission (FTC) protocol. However, the actual exposure of nicotine to smokers depends on their own smoking behavior. The nicotine ring system is relatively thermally stable. Protonated nicotine forms nicotine which evaporates before the nicotine ring system decomposes. The experimental data indicate that neither nicotine transfer from tobacco to MS smoke nor nicotine bioavailability to the smoker increases with an increase in any of the following properties: tobacco soluble ammonia, MS smoke ammonia, "tobacco pH" or "smoke pH" at levels found in commercial cigarettes. Gas phase nicotine deposits primarily in the mouth and upper respiratory tract. To the extent that ammonia increases the deposition of nicotine in the buccal cavity and upper respiratory tract during smoking, the total rate and amount of nicotine into the arterial bloodstream and to the central nervous system will decrease. Charged nicotine analogues are actively transported in a number of tissues. This active transport system appears to be insensitive to pH and the form of nicotine in the biological milieu, suggesting that protonated nicotine may be a substrate for active transport. Neither "smoke pH" of commercial cigarettes nor "smoke pHeff" nor the fraction of non-protonated nicotine in tobacco smoke particulate matter are useful, practical smoke parameters for providing understanding or predictability of nicotine bioavailability to smokers. Greater than 95% of both ammonia and nicotine are in the gas phase of environmental tobacco, and both are likely to deposit in the buccal cavity and upper respiratory tract following exposure.

Cigarette smoke chemistry market maps under Massachusetts Department of Public Health smoking conditions

This study extends the market mapping concept introduced by Counts et al. (Counts, M.E., Hsu, F.S., Tewes, F.J., 2006. Development of a commercial cigarette "market map" comparison methodology for evaluating new or non-conventional cigarettes. Regul. Toxicol. Pharmacol. 46, 225-242) to include both temporal cigarette and testing variation and also machine smoking with more intense puffing parameters, as defined by the Massachusetts Department of Public Health (MDPH). The study was conducted over a two year period and involved a total of 23 different commercial cigarette brands from the U.S. marketplace. Market mapping prediction intervals were developed for 40 mainstream cigarette smoke constituents and the potential utility of the market map as a comparison tool for new brands was demonstrated. The over-time character of the data allowed for the variance structure of the smoke constituents to be more completely characterized than is possible with one-time sample data. The variance was partitioned among brand-to-brand differences, temporal differences, and the remaining residual variation using a mixed random and fixed effects model. It was shown that a conventional weighted least squares model typically gave similar prediction intervals to those of the more complicated mixed model. For most constituents there was less difference in the prediction intervals calculated from over-time samples and those calculated from one-time samples than had been anticipated. One-time sample maps may be adequate for many purposes if the user is aware of their limitations. Cigarette tobacco fillers were analyzed for nitrate, nicotine, tobacco-specific nitrosamines, ammonia, chlorogenic acid, and reducing sugars. The filler information was used to improve predicting relationships for several of the smoke constituents, and it was concluded that the effects of filler chemistry on smoke chemistry were partial explanations of the observed brand-to-brand variation.

Toxicological comparisons of three styles of a commercial U.S. cigarette (Marlboro with the 1R4F reference cigarette

Toxicological comparisons were made of three commercial cigarettes, namely Marlboro full flavor, Marlboro Lights, and Marlboro Ultra Lights, with the 1R4F reference cigarette. The main comparison was a 90-d inhalation study with mainstream smoke at 150 mg total particulate matter per cubic meter, in Sprague-Dawley rats using 6 h/d and 7 d/w exposures. The principal endpoint was histopathology of the respiratory tract, along with examinations of free lung cell counts after broncho-alveolar lavage. Additional studies on mainstream smoke included Salmonella mutagenicity, cytotoxicity of particulate and gas/vapor phases, and analytical chemistry. The exposures produced effectively the same responses in each of the four groups, and the histopathology results in the commercial cigarette groups were also effectively the same. The 1R4F was also tested at 75 and 200 mg/m(3), and most of the histopathology results obtained here showed dose-response relationships. The free lung cell responses were similar in the 1R4F/commercial cigarette comparison, and there were dose-related changes in the 1R4F groups, most notably for neutrophils. Most of the changes produced in the 90-d of exposure were resolved in a 42-d post-inhalation period. Responses in the in vitro and analytical assays for the four cigarettes were in general similar, when data were expressed either per mg TPM or per mg tar yield. There were judged to be no toxicologically meaningful differences between the profiles evaluated at similar smoke concentrations for the three commercial cigarettes and for the 1R4F using these assays.

Reduced toxicological activity of cigarette smoke by the addition of ammonium magnesium phosphate to the paper of an electrically heated cigarette: smoke chemistry and in vitro cytotoxicity and genotoxicity

The effects of the addition of ammonium magnesium phosphate (AMP) to the paper of an electrically heated cigarette (EHC) prototype on smoke composition and toxicity were quantified and the underlying mechanisms investigated. Smoke from EHC prototypes with and without AMP and from conventional cigarettes, i.e. the University of Kentucky Standard Reference Cigarette 1R4F and eight American-blend market cigarettes, was compared. Endpoints for comparison were smoke chemistry, where toxic constituents were measured, cytotoxic activity, as measured in murine fibroblasts embryo cells by the Neutral Red Uptake Assay, and genotoxic activity, as measured in bacteria by the Salmonella Reverse Mutation Assay and in murine lymphoma cells by the TK Assay. The addition of AMP to the EHC led to a reduction of toxic substances and toxicological activity of approximately 30% compared to the EHC without AMP. Compared to the conventional cigarettes, the EHC with AMP showed reductions of 75-90%. Smoke from the EHCs generated in nitrogen atmospheres supplemented with different concentrations of ammonia and oxygen was assayed for its in vitro cytotoxicity and genotoxicity. The results indicate that the ammonia released by AMP at the heating site of the EHC is responsible for the reductions in cytotoxicity and mutagenicity for the EHC with AMP compared with the EHC without AMP. Thus, while the EHC approach distinctly reduces toxic smoke constituents compared to conventional cigarettes, the use of AMP in the paper of an EHC leads to further distinct reductions. In the study presented here, in vitro assays were used as quantitative tools to investigate toxicity-related mechanisms.

Evaluation of nitrate influence on thyroid volume of adults in a previously iodine-deficient area

OBJECTIVE

The aim of the present study was to analyze the influence of nitrate as a possible alimentary goitrogen on thyroid volume in a previously iodine-deficient area.

DESIGN

Population based cross-sectional epidemiologic survey.

PARTICIPANTS

Data of 3772 participants (20-79 years) of the Study of Health in Pomerania without diagnosed thyroid disorders were analyzed. EVALUATION AND MEASUREMENTS: The nitrate concentration in spot urine was determined by ion chromatography. High nitrate levels were defined as urine nitrate concentrations exceeding the 75th percentile for the investigated population. Thyroid structure and size were measured by ultrasound. Subjects were divided into two groups with absence or presence of high urine nitrate concentrations. Comparisons between groups were made using the chi(2)-test or the Student's t-test. Multivariable analyses were done by logistic regression and ANOVA (analysis of variance). Odds ratios and their 95% confidence intervals as well as adjusted means (standard error) were calculated.

RESULTS

In the whole population, the mean urine nitrate level was 53.1+/-0.8mg/l. The 75th percentile of urine nitrate concentrations was 69.0mg/l, indicating that the renal excretion of nitrate is at a low level. The proportion of goiter in subjects with and without high urine nitrate concentrations was 35.5% and 34.7%, respectively (p=0.69). Analyses considering age, sex and further potential confounders could not identify an association between the exposure variable and the risk of goiter.

CONCLUSION

The low level of the alimentary nitrate intake does not influence the thyroid volume in a population with currently sufficient alimentary intake of iodine.

Palladium alters cigarette smoke toxicological profile, but accumulates in the lungs of rats during inhalation exposure

The use of a palladium (Pd) catalyst has been proposed to promote combustion of tobacco, thereby reducing concentrations of certain toxic components of smoke, including polyaromatic hydrocarbons (PAHs). In the present work, toxicological comparisons were made using experimental cigarettes containing no added Pd, against otherwise similar cigarettes containing three different amounts of Pd as potassium tetrachloropalladate added to the tobacco. A full analysis of smoke chemistry was made, along with a subchronic 90-day inhalation study with mainstream smoke (rats exposed to 150 mg/m(3) of total particulate matter, 6 h/day for 90 consecutive days) and in vitro evaluations of Salmonella mutagenicity, cytotoxicity, and in vivo clastogenicity (micronucleus). Addition of Pd to the tobacco resulted in 20-30% reductions in the concentrations of 6 PAHs and 2 aromatic amines, but it also resulted in transfer of Pd to smoke and in 10-50% increases in concentrations of several tobacco-specific nitrosamines. Mutagenicity was reduced by about 50% in 2 of 5 strains of Salmonella (with S9 only), while the cytotoxicity and micronucleus assays showed no changes. Histopathology responses were similar across the four smoke inhalation groups. Smoke Cd was reduced by 40-70% in the smoke, leading to lower lung concentrations; however, the presence of Pd in smoke led to accumulation of Pd in the lungs increasing in both a dose-and an exposure-related manner. While catalysts such as Pd addition may alter the typical chemical/toxicological profile of smoke, a concern arises regarding the "risk-benefit" of the addition of such chemically active materials as Pd to cigarette tobacco, leading to potential pulmonary accumulation with unknown consequences.

Dependence of tar, nicotine and carbon monoxide yields on physical parameters: implications for exposure, emissions control and monitoring

OBJECTIVE

To estimate the extent to which tar, nicotine and carbon monoxide (TNCO) yields are dependent on cigarette design features such as burn rate, filter ventilation and paper porosity, and to consider the implications for human exposure and the regulation of TNCO emissions. A related aim is to determine whether accurate prediction of TNCO yields is possible using only simple physical parameters.

DESIGN AND METHODS

Datasets that include quantitative design parameters as well as measurements of TNCO yields collected under standard conditions with vents unblocked (International Organization for Standardization) and under intense conditions with vents fully blocked (Health Canada) were compiled from the literature (primarily US and UK brands). Forward stepwise multiple regression analysis is used to assess the relative importance of each design feature in explaining variability in the observed emissions. Using randomly split data subsets, multiple linear regression is used to model the dependence of TNCO yields on design features in the training subset and validated against the test subset. Tar and carbon monoxide correlate with many of the particulate- and volatile-phase toxins in smoke, and brand values normalised to nicotine yield are used as surrogate measures of exposure within the bounds defined by non-intense and intense smoking protocols.

RESULTS AND CONCLUSIONS

Filter ventilation is the dominant control on measured TNCO emissions, but other factors including burn rate, amount of tobacco and paper porosity also contribute. Yields are predictable with reasonable accuracy and precision using only measured physical parameters. Surrogate exposure indicators suggest that filter ventilation does not lead to any reduction in exposure and that highly ventilated (low-yield) brands may actually increase exposure to the more volatile toxins.