Comparison of Environmental Tobacco Smoke (ETS) Concentrations Generated by an Electrically Heated Cigarette Smoking System and a Conventional Cigarette

Smoking conventional lit-end cigarettes results in exposure of nonsmokers to potentially harmful cigarette smoke constituents present in environmental tobacco smoke (ETS) generated by sidestream smoke emissions and exhaled mainstream smoke. ETS constituent concentrations generated by a conventional lit-end cigarette and a newly developed electrically heated cigarette smoking system (EHCSS) that produces only mainstream smoke and no sidestream smoke emissions were investigated in simulated “office” and “hospitality” environments with different levels of baseline indoor air quality. Smoking the EHCSS (International Organisation for Standardization yields: 5 mg tar, 0.3 mg nicotine, and 0.6 mg carbon monoxide) in simulated indoor environments resulted in significant reductions in ETS constituent concentrations compared to when smoking a representative lit-end cigarette (Marlboro: 6 mg tar, 0.5 mg nicotine, and 7 mg carbon monoxide). In direct comparisons, 24 of 29 measured smoke constituents (83%) showed mean reductions of greater than 90%, and 5 smoke constituents (17%) showed mean reductions between 80% and 90%. Gas–vapor phase ETS markers (nicotine and 3-ethenylpyridine) were reduced by an average of 97% (range 94–99%). Total respirable suspended particles, determined by online particle measurements and as gravimetric respirable suspended particles, were reduced by 90% (range 82–100%). The mean and standard deviation of the reduction of all constituents was 94?±?4%, indicating that smoking the new EHCSS in simulated “office” and “hospitality” indoor environments resulted in substantial reductions of ETS constituents in indoor air.     

Environmental tobacco smoke (ETS) evaluation of a third-generation electrically heated cigarette smoking system (EHCSS)

This sub-study of a randomized, controlled, forced-switching, open-label, parallel-group, clinical study compared environmental tobacco smoke (ETS) produced when 60 male and female adult smokers switched to a third-generation electrically heated cigarette smoking system (EHCSS), continued to smoke a conventional cigarette (CC), or stopped smoking (No-smoking). Concentrations of air constituents including respirable suspended particulate (RSP), carbon monoxide (CO), ammonia and total volatile organic compounds (TVOCs) and ETS markers including solanesol-related particulate matter (Sol-PM), ultraviolet absorbing particulate matter (UVPM), fluorescent particulate matter (FPM), nicotine and 3-ethenyl pyridine (3-EP) were measured in a ventilated, furnished conference room over a 2-h period on separate occasions for each smoking condition. When the EHCSS was used, concentrations of CO and most ETS markers were in the same range as during no-smoking. Concentrations of ammonia were reduced by 41% and concentrations of other selected constituents of ETS were reduced by 87-99% in the air of a room in which EHCSS cigarettes were smoked as compared to concentrations in the same room when conventional cigarettes were smoked. Switching from conventional cigarette smoking to the EHCSS resulted in substantial reductions in concentrations of several markers of environmental tobacco smoke.     

Smoke chemistry, in vitro and in vivo toxicology evaluations of the electrically heated cigarette smoking system series K

The Electrically Heated Cigarette Smoking System Series K (EHCSS) produces smoke through the controlled electrical heating of tobacco. Evaluation of the EHCSS was accomplished by comparison with commercial and reference cigarettes, using International Organization for Standardization (ISO) and alternative puffing regimens based on nicotine exposures measured in a short-term clinical study. Using the alternative puffing regimen and compared with conventional cigarettes on a per cigarette basis, the EHCSS had 50–60% reductions in tar and nicotine; at least 90% reductions in carbon monoxide, nitrogen oxides, 1,3-butadiene, isoprene, acrylonitrile, polyaromatic hydrocarbons, hydrogen cyanide, aromatic amines, tobacco specific nitrosamines, and phenol; and least a 40% reduction in 2-nitropropane. Other important smoke constituents in EHCSS smoke were reduced as well. The in vitro studies showed similar large reductions in biological activity. Ames mutagenicity of total particulate matter (TPM) from the EHCSS was reduced by 70–90%; cytotoxicity of the TPM was reduced by approximately 82% and 65% for the gas–vapor phase. In vivo testing under ISO smoking conditions in the mouse skin painting assay demonstrated later dermal tumor onset, lower dermal tumor incidence, reduced dermal tumor multiplicity, and a lower proportion of malignant dermal tumors in EHCSS smoke condensate-exposed mice. Thirty-five day and 90-day nose-only inhalation studies in rats showed reductions in pulmonary inflammation and other biological activity, including histopathological endpoints. We conclude that under the conditions of these in vitro and in vivo studies, the EHCSS demonstrated significantly lower biological activity compared to conventional cigarettes, and may suggest the potential for reductions in human smokers.     

Short-term exposure evaluation of adult smokers switching from conventional to first-generation electrically heated cigarettes during controlled smoking

This randomized, controlled study in 110 male and female adult smokers evaluated biomarkers of tobacco smoke exposure (carbon monoxide [CO], carboxyhemoglobin [CO-Hb], nicotine, urine mutagenicity) under controlled smoking conditions when adult smokers of 1 conventional cigarette brand (CC1) were switched to an electrically heated cigarette smoking system (EHCSS) or a low-tar conventional cigarette (CC2). Baseline exposure was determined while all subjects smoked CC1. Subjects then were stratified for gender and cigarette consumption and randomized to 1 of 5 groups-EHCSS1, EHCSS2, CC1, CC2, or no smoking-and monitored for 8 days. Compared to baseline, biomarkers of exposure on day 8 decreased 53% to 93% (P < .0001) for EHCSS groups and 18% to 39% (P < .02) for CC2. Environmental tobacco smoke arising from the smoking activities of the different study groups was measured in the air of a separate smoking room over 1-hour periods. Concentrations of respirable suspended particulates in both EHCSS groups were about 90% lower than in the CC1 and CC2 groups, similar to the 95% reduction in the no-smoking group. CO was undetectable in the EHCSS and no-smoking groups. Results from this short-term clinical study indicate that switching from a conventional cigarette to a first-generation EHCSS reduces the generation of environmental tobacco smoke and can reduce the exposure to the measured, potentially harmful constituents in tobacco smoke if smokers do not compensate by numbers of cigarettes. The study design was found to be suitable for the evaluation of the exposure of adult smokers to the measured smoke constituents and to allow the differentiation of different cigarette designs.     

Short-term clinical exposure evaluation of a third-generation electrically heated cigarette smoking system (EHCSS) in adult smokers

This randomized, controlled, forced-switching, open-label, parallel-group, single-center study in 100 male and female adult smokers evaluated 12 biomarkers of tobacco smoke exposure. We measured exposure to the following smoke constituents: nicotine, pyrene, tobacco-specific nitrosamines, three aromatic amines, carbon monoxide, benzene, acrolein, crotonaldehyde, and 1,3-butadiene. After baseline exposure determination, adult smokers of a conventional cigarette (CC) were switched to an electrically heated cigarette smoking system (EHCSS, Series K), continued smoking the CC, or stopped smoking (No-smoking) for 8 days in a controlled, confined, clinical setting. In the EHCSS group, the mean decrease from Baseline to Day 8 in the biomarkers of exposure ranged from 16% to 77% at Day 8 compared to Baseline. After adjusting for the residual effect (carryover effects due to long elimination half-life and non-tobacco confounding sources of exposure), the mean percent decrease from Baseline for all 12 biomarkers ranged from 47% to 90%. In conclusion, switching for 8 days from a conventional cigarette to the EHCSS substantially reduced exposure of adult smokers to several constituents of both the particulate and gas phases of cigarette smoke.     

12-week clinical exposure evaluation of a third-generation electrically heated cigarette smoking system (EHCSS) in adult smokers

This randomized, controlled, forced-switching, open-label, parallel-group, single-center study in 90 male and female adult smokers evaluated six biomarkers of tobacco smoke exposure over a 12-week period of unrestricted smoking in the participants' normal life setting. Baseline biomarker levels were measured, then participants were randomly assigned to switch to an electrically heated cigarette smoking system (EHCSS, Series K) or to continue smoking a conventional cigarette (CC) of similar tar yield (Federal Trade Commission method) for 12 weeks. Compared to Baseline, adult smokers who switched to the EHCSS for 12 weeks in their normal life setting had significantly reduced nicotine equivalents (-33%), total NNAL (a biomarker for NNK, -63%), 1-OHP (a surrogate biomarker for polycyclic aromatic hydrocarbons, -38%), carboxyhemoglobin (a biomarker for carbon monoxide, -23%), 3-HPMA (a biomarker for acrolein, -25%) and S-PMA (a biomarker for benzene, -49%), whereas exposure was stable in the CC control group.     

Reduced toxicological activity of cigarette smoke by the addition of ammonia magnesium phosphate to the paper of an electrically heated cigarette: subchronic inhalation toxicology

Cigarette smoke is a complex chemical mixture that causes a variety of diseases, such as lung cancer. With the electrically heated cigarette smoking system (EHCSS), temperatures are applied to the tobacco below those found in conventional cigarettes, resulting in less combustion, reduced yields of some smoke constituents, and decreased activity in some standard toxicological tests. The first generation of electrically heated cigarettes (EHC) also resulted in increased formaldehyde yields; therefore, a second generation of EHC was developed with ammonium magnesium phosphate (AMP) in the cigarette paper in part to address this increase. The toxicological activity of mainstream smoke from these two generations of EHC and of a conventional reference cigarette was investigated in two studies in rats: a standard 90-day inhalation toxicity study and a 35-day inhalation study focusing on lung inflammation. Many of the typical smoke exposure-related changes were found to be less pronounced after exposure to smoke from the second-generation EHC with AMP than to smoke from the first-generation EHC or the conventional reference cigarette, when compared on a particulate matter or nicotine basis. Differences between the EHC without AMP and the conventional reference cigarette were not as prominent. Overall, AMP incorporated in the EHC cigarette paper reduced the inhalation toxicity of the EHCSS more than expected based on the observed reduction in aldehyde yields.     

Comparison of the impact of the Tobacco Heating System 2.2 and a cigarette on indoor air quality

The impact of the Tobacco Heating System 2.2 (THS 2.2) on indoor air quality was evaluated in an environmentally controlled room using ventilation conditions recommended for simulating “Office”, “Residential” and “Hospitality” environments and was compared with smoking a lit-end cigarette (Marlboro Gold) under identical experimental conditions. The concentrations of eighteen indoor air constituents (respirable suspended particles (RSP) < 2.5 μm in diameter), ultraviolet particulate matter (UVPM), fluorescent particulate matter (FPM), solanesol, 3-ethenylpyridine, nicotine, 1,3-butadiene, acrylonitrile, benzene, isoprene, toluene, acetaldehyde, acrolein, crotonaldehyde, formaldehyde, carbon monoxide, nitrogen oxide, and combined oxides of nitrogen) were measured. In simulations evaluating THS 2.2, the concentrations of most studied analytes did not exceed the background concentrations determined when non-smoking panelists were present in the environmentally controlled room under equivalent conditions. Only acetaldehyde and nicotine concentrations were increased above background concentrations in the “Office” (3.65 and 1.10 μg/m³), “Residential” (5.09 and 1.81 μg/m³) and “Hospitality” (1.40 and 0.66 μg/m³) simulations, respectively. Smoking Marlboro Gold resulted in greater increases in the concentrations of acetaldehyde (58.8, 83.8 and 33.1 μg/m³) and nicotine (34.7, 29.1 and 34.6 μg/m³) as well as all other measured indoor air constituents in the “Office”, “Residential” and “Hospitality” simulations, respectively.     

Short-term clinical exposure evaluation of a second-generation electrically heated cigarette smoking system

This randomized, controlled, forced-switching, open-label, parallel-group study in 100 adult male and female smokers of conventional cigarettes evaluated 8 biomarkers of tobacco smoke exposure. After baseline exposure determinations, adult smokers were switched to a second-generation electrically heated cigarette smoking system (EHCSS) for 8 days in a clinical setting. After 8 days of smoking the EHCSS biomarkers of exposure decreased by 43% to 85% compared to baseline. After correction for residual effects (carryover effects due to long elimination half-life and non-tobacco-confounding sources of exposure), reductions in exposure ranged from 59% to 97%. Results from this short-term clinical exposure study indicate that switching from a conventional cigarette to a second-generation electrically heated cigarette smoking system substantially reduced the exposure to several measured potentially harmful constituents of tobacco smoke.     

Evaluation of a low to middle tar/medium nicotine cigarette designed to maintain nicotine delivery to the smoker

A specific objective of this 6-week crossover study was to determine how 21 regular smokers of middle tar cigarettes changed their smoking behaviour and uptake of smoke constituents, when switching to either lower tar cigarettes capable of delivering amounts of nicotine similar to a conventional middle tar cigarette (maintained nicotine product), or to conventional low tar/low nicotine cigarettes. Subjects visited the laboratory every 2 weeks for detailed assessment of their smoking behaviour. Weekly per capita consumption was similar for all three cigarettes. They were smoked with variable intensities (low tar > maintained nicotine > middle tar), the tendency being for larger puff volumes, faster puffing and increased puff duration with the low tar cigarettes. The maintained nicotine cigarette was preferred to the middle tar cigarette, although acceptability ratings of the three cigarettes only differed marginally. The nicotine absorbed from the maintained nicotine and middle tar cigarettes was similar and significantly greater than the levels achieved from the low tar cigarettes. Intake of carbon monoxide into the mouth and absorption into the blood stream was lower for the maintained nicotine cigarette than for the middle tar cigarette, with the low tar cigarette occupying an intermediate position. Derived estimates of tar intake suggested reduced intake of tar into the respiratory tract (around 25%) from the maintained nicotine product relative to the middle tar product. The possible advantages of switching to maintained nicotine cigarettes is discussed.     

Toxicological evaluation of an electrically heated cigarette. Part 2: Chemical composition of mainstream smoke

The chemical composition of mainstream smoke from an electrically heated cigarette (EHC) and that of mainstream smoke from the University of Kentucky Reference Cigarette 1R4F was analyzed.In contrast to the 1R4F, which is a conventional, lit-end cigarette, the EHC is smoked in a microprocessor-controlled lighter with electrical heater elements. The electrical heating causes the tobacco under the heater element to burn at a low temperature during each puff. A comprehensive list of chemical constituents was analyzed in mainstream smoke. The list is a combination of those compounds suggested for analysis in cigarette smoke by a US Consumer Product Safety Commission proposal in 1993, and those cigarette smoke constituents identified by the International Agency on Research on Cancer as being present in cigarette smoke and characterized as carcinogens. The low pyrolysis/combustion temperature of tobacco in the EHC causes distinct shifts in the composition of the smoke compared with a conventional cigarette. A significant drop was seen in the yields of almost all toxicologically relevant constituents. On a per cigarette basis almost two-thirds of the constituents were reduced by at least 80%, whereas on an equal total particulate matter basis about two-thirds of the constituents were reduced by at least 50%, with many constituents reduced by more than 90%.     

Long-term effects of switching to cigarettes with lower tar and nicotine yields

On switching to cigarettes with lower tar and nicotine yields, most individuals smoke more intensively, but it is not clear if this effect persists over a long period. Smoking behaviour was monitored in 10 male and 18 female volunteers at five monthly visits, smoking commercially available cigarettes (tar yield>10 mg), then for six more visits at 6-week intervals after switching (mean reduction of 5.9 mg tar and 0.45 mg nicotine). Puffing behaviour was monitored with a flow sensing holder, and measurements were made before and after smoking of plasma cotinine, carboxyhaemglobin and alveolar carbon monoxide. After switching, cotinine levels only fell 40% of that predicted from the fall in nicotine yields, and there were no systematic trends for the rest of the study. Puff volumes rose (reflecting perhaps the reduced draw resistance of the lower yield cigarettes), and remained higher thereafter. The number of puffs per cigarette appeared to rise on switching, but then decreased again. In conclusion, most effects of switching to lower yield cigarettes appeared to persist for at least 36 weeks, suggesting that the strategy of reducing exposure to cigarette smoke by lowering tar and nicotine yields may be of limited value.     

Estimation of mouth level exposure to smoke constituents of cigarettes with different tar levels using filter analysis

A nicotine part-filter method can be applied to estimate smokers’ mouth level exposure (MLE) to smoke constituents. The objectives of this study were (1) to generate calibration curves for 47 smoke constituents, (2) to estimate MLE to selected smoke constituents using Japanese smokers of commercially available cigarettes covering a wide range of International Organization for Standardization tar yields (1–21 mg/cigarette), and (3) to investigate relationships between MLE estimates and various machine-smoking yields. Five cigarette brands were machine-smoked under 7 different smoking regimes and smoke constituents and nicotine content in part-filters were measured. Calibration curves were then generated. Spent cigarette filters were collected from a target of 50 smokers for each of the 15 brands and a total of 780 filters were obtained. Nicotine content in part-filters was then measured and MLE to each smoke constituent was estimated. Strong correlations were identified between nicotine content in part-filters and 41 out of the 47 smoke constituent yields. Estimates of MLE to acetaldehyde, acrolein, 1,3-butadiene, benzene, benzo[a]pyrene, carbon monoxide, and tar showed significant negative correlations with corresponding constituent yields per mg nicotine under the Health Canada Intense smoking regime, whereas significant positive correlations were observed for N-nitrosonornicotine and (4-methylnitrosoamino)-1-(3-pyridyl)-1-butanone.     

Analytical cigarette yields as predictors of smoke bioavailability

The smoke intake of 865 undisturbed smokers of over 10 cigarettes per day was measured using plasma nicotine and cotinine, and expired carbon monoxide (CO) as markers. While nicotine yields, according to Federal Trade Commission (FTC) analytical standards, varied 16-fold from 0.1 to 1.6 mg/cigarette, the corresponding plasma nicotine values varied from around 25 to 45 ng/ml, and estimated mean nicotine intake of smokers varied from around 0.75 to 1.25 mg/cigarette. Expired CO and plasma cotinine values also varied in similar proportion, but mean daily cigarette consumption was independent of the FTC nicotine yield of the cigarettes smoked. The results indicate that pharmacodynamic satiation causes behavioral regulation, and that smokers of very high yield brands compensate downward, and vice versa. The ratio of tar yield to nicotine yield usually increases with increasing tar yield; therefore tar intake is likely to increase at higher tar yields, even though the increment of nicotine intake is small. It follows that FTC analytical determinations are poor predictors of relative intake of nicotine, CO, or tar, while rankings based on mean tar-to-nicotine ratio of a brand's smoke could be more meaningful. Moreover, the considerable variation of individual smoking behavior suggests that precise numerical rankings of cigarettes are not justified. An analogic ranking of cigarettes into a few broad classes would better reflect the realities and expectations of average consumers.     

Distribution of Major and Minor Alkaloids in Tobacco, Mainstream and Sidestream Smoke of Popular Indian Smoking Products

Various Indian smoking products—cigarette, bidi, chutta and a brand of US cigarette—were analysed by gas chromatography–flame ionization detection (GC–FID) for the levels of nicotine and minor tobacco alkaloids in tobacco, mainstream smoke (MS) and sidestream smoke (SS) employing modified smoking standards, namely two puffs/min. The analysis clearly demonstrated relatively higher levels of nicotine and minor tobacco alkaloids in tobacco from bidi (37.7 mg/g) and chutta (34.5 mg/g) when compared with Indian and US cigarettes (14–16 mg/g) studied. Relatively lower levels (SS/MS) of nicotine in SS from bidi and chutta compared with Indian/US cigarettes, suggest that the contribution of nicotine in SS from a single bidi/chutta to environmental tobacco smoke (ETS) is very much less than that of a single Indian/US cigarette. Reduced levels of nicotine in SS of bidi/chutta result in relatively higher deliveries of nicotine in MS as reflected by higher MS/SS values. The observed differences are likely to be due to difference in tobacco processing, burning rate/temperature and design of the smoking product.     

Reduced Toxicological Activity of Cigarette Smoke by the Addition of Ammonia Magnesium Phosphate to the Paper of an Electrically Heated Cigarette: Subchronic Inhalation Toxicology

Cigarette smoke is a complex chemical mixture that causes a variety of diseases, such as lung cancer. With the electrically heated cigarette smoking system (EHCSS), temperatures are applied to the tobacco below those found in conventional cigarettes, resulting in less combustion, reduced yields of some smoke constituents, and decreased activity in some standard toxicological tests. The first generation of electrically heated cigarettes (EHC) also resulted in increased formaldehyde yields; therefore, a second generation of EHC was developed with ammonium magnesium phosphate (AMP) in the cigarette paper in part to address this increase. The toxicological activity of mainstream smoke from these two generations of EHC and of a conventional reference cigarette was investigated in two studies in rats: a standard 90-day inhalation toxicity study and a 35-day inhalation study focusing on lung inflammation. Many of the typical smoke exposure-related changes were found to be less pronounced after exposure to smoke from the second-generation EHC with AMP than to smoke from the first-generation EHC or the conventional reference cigarette, when compared on a particulate matter or nicotine basis. Differences between the EHC without AMP and the conventional reference cigarette were not as prominent. Overall, AMP incorporated in the EHC cigarette paper reduced the inhalation toxicity of the EHCSS more than expected based on the observed reduction in aldehyde yields.     

Influence of cigarette circumference on smoke chemistry,biological activity,and smoking behaviour

Cigarettes with reduced circumference are increasingly popular in some countries, hence it is important to understand the effects of circumference reduction on their burning behaviour, smoke chemistry and bioactivity. Reducing circumference reduces tobacco mass burn rate, puff count and static burn time, and increases draw resistance and rod length burned during puff and smoulder periods. Smoulder temperature increases with decreasing circumference, but with no discernible effect on cigarette ignition propensity during a standard test. At constant packing density, mainstream (MS) and sidestream (SS) tar and nicotine yields decrease approximately linearly with decreasing circumference, as do the majority of smoke toxicants. However, volatile aldehydes, particularly formaldehyde, show a distinctly non-linear relationship with circumference and increases in the ratios of aldehydes to tar and nicotine have been observed as the circumference decreases. Mutagenic, cytotoxic and tumorigenic specific activities of smoke condensates (i.e. per unit weight of condensate) decrease as circumference decreases. Recent studies suggest that there is no statistical difference in mouth-level exposure to tar and nicotine among smokers of cigarettes with different circumferences. Commercially available slim cigarettes usually have changes in other cigarette design features compared with cigarettes with standard circumference, so it is difficult to isolate the effect of circumference on the properties of commercial products. However, available data shows that changes in cigarette circumference offer no discernible change to the harm associated with smoking.     

Relationship between cigarette format and mouth-level exposure to tar and nicotine in smokers of Russian king-size cigarettes

Differences in length and circumference of cigarettes may influence smoker behaviour and exposure to smoke constituents. Superslim king-size (KSSS) cigarettes (17 mm circumference versus 25 mm circumference of conventional king-size [KS] cigarettes), have gained popularity in several countries, including Russia. Some smoke constituents are lower in machine-smoked KSSS versus KS cigarettes, but few data exist on actual exposure in smokers. We investigated mouth-level exposure (MLE) to tar and nicotine in Russian smokers of KSSS versus KS cigarettes and measured smoke constituents under machine-smoking conditions. MLE to tar was similar for smokers of 1 mg ISO tar yield products, but lower for smokers of 4 mg and 7 mg KSSS versus KS cigarettes. MLE to nicotine was lower in smokers of 4 mg KSSS versus KS cigarettes, but not for other tar bands. No gender differences were observed for nicotine or tar MLE. Under International Organization for Standardization, Health Canada Intense and Massachusetts regimes, KSSS cigarettes tended to yield less carbon monoxide, acetaldehyde, nitric oxide, acrylonitrile, benzene, 1,3-butadiene and tobacco-specific nitrosamines, but more formaldehyde, than KS cigarettes. In summary, differences in MLE were observed between cigarette formats, but not systematically across pack tar bands.     

The mouse lymphoma thymidine kinase assay for the assessment and comparison of the mutagenic activity of cigarette mainstream smoke particulate phase

The mouse lymphoma thymidine kinase assay (MLA) has been optimized to quantitatively determine the in vitro mutagenicity of cigarette mainstream smoke particulate phase. To test whether the MLA is able to discriminate between different cigarette types, specially constructed cigarettes each containing a single tobacco type - Bright, Burley, or Oriental - were investigated. The mutagenic activity of the Burley cigarette was statistically significantly lower, up to approximately 40%, than that of the Bright and Oriental cigarettes. To determine the impact of two different sets of smoking conditions, American-blend cigarettes were smoked under US Federal Trade Commission/International Organisation for Standardisation conditions and under Massachusetts Department of Public Health (MDPH) conditions. Conventional cigarettes - eight from the US commercial market plus the Reference Cigarettes 1R4F and 2R4F - and an electrically heated cigarette smoking system (EHCSS) prototype were tested. There were no statistically significant differences between the two sets of smoking conditions on a per mg total particulate matter basis, although there was a consistent trend towards slightly lower mutagenic activity under MDPH conditions. The mutagenic activity of the EHCSS prototype was distinctly lower than that of the conventional cigarettes under both sets of smoking conditions. These results show that the MLA can be used to assess and compare the mutagenic activity of cigarette mainstream smoke particulate phase in the comprehensive toxicological assessment of cigarette smoke.     

Toxicological evaluation of glycerin as a cigarette ingredient.

Glycerin is applied to cigarette tobacco at levels in the range of about 1-5% to improve moisture holding characteristics of tobacco and act as a surface active agent for flavor application. Neat material pyrolysis studies, smoke chemistry and biological activity studies (bacterial mutagenicity, cytotoxicity, in vivo micronucleus, and sub-chronic rodent inhalation) with mainstream smoke, or mainstream smoke preparations from cigarettes containing various target levels (5%, 10%, and 15%) of the glycerin were performed to provide data for an assessment of the use of glycerin as a cigarette tobacco ingredient. The actual levels of glycerin in the respective test cigarettes were determined to be 3.2%, 6.2% and 8.4% after cigarette production. At simulated tobacco burning temperatures up to 900 degrees C, neat glycerin did not pyrolyze extensively suggesting that glycerin would transfer intact to mainstream smoke (smoke was not analyzed for glycerin in this study). On a tar basis, nicotine in smoke was significantly decreased at 10% and 15% glycerin while water was increased at all addition levels. Addition of 10% or 15% glycerin also resulted in a statistically significant increase in acrolein (9%) and a decrease in acetaldehyde, propionaldehyde, aromatic amines, nitrogen oxides, tobacco specific nitrosamines, and phenols. Addition of 5% glycerin produced the same decrease in smoke constituents as the 10% and 15% groups but there was no concomitant increase in acrolein. Biological tests indicated no relevant differences in the genotoxic or cytotoxic potential of either mainstream smoke (or smoke preparations) from cigarettes with added glycerin compared to control cigarettes. Cigarette smoke atmosphere dilution, coupled with the lower nicotine delivery in the test cigarettes containing glycerin resulted in a lower nicotine delivery to the glycerin cigarette smoke exposed rats of the 90-day inhalation study. Smoke atmosphere acrolein was also reduced in a concentration-related manner. Incorporation of glycerin at target levels up to 15% did not produce any adverse effects in rats exposed for 90-days. The major observation in the study was a reduced biological activity of the smoke as indicated by a reduction in the severity and/or incidence of focal macrophage accumulation in the lungs and goblet cell hyperplasia/hypertrophy in the nose (level 1), and goblet cell staining depletion in the nose (level 1). The results of these studies with glycerin applied to cigarette tobacco suggest that adding glycerin to cigarette tobacco at typical use levels does not adversely alter the smoke chemistry or biological effects normally associated with exposure to mainstream cigarette smoke.