Limitations of cigarette machine smoking regimens

Little Cigars, Filtered Cigars, and their Carbonyl Delivery Relative to Cigarettes

Introduction

Little cigars and filtered cigars are currently growing in popularity due to their low cost and wide variety of flavors while retaining an appearance similar to cigarettes. Given the health consequences associated with cigarette use, it is important to understand the potential harm associated with these similar products. This includes the potential harm associated with carbonyls (eg, acetaldehyde, acrolein, formaldehyde, etc.), an important class of toxicants and carcinogens in tobacco smoke. Our objective was to determine the carbonyl levels in mainstream smoke from little and filtered cigars compared to cigarettes.

Methods

We examined two brands each of little cigars and filtered cigars, as well as two research cigarettes for carbonyl delivery using the International Organization of Standards (ISO) and the Health Canada Intense (HCI) machine-smoking protocols.

Results

On a per puff basis, the levels of five of the seven carbonyls were higher from little cigars than filtered cigars and cigarettes (ISO: 56-116%; HCI: 39-85%; p < .05). On a per unit basis, most carbonyl levels were higher from both cigar types than cigarettes using the ISO method (ISO: 51-313%; p < .05) whereas only filtered cigars were higher using the HCI method (HCI: 53-99%; p < .05).

Conclusion

These findings suggest that cigar smokers can be exposed to higher levels of carbonyls per cigar than cigarette smokers per cigarette.

Implications

These data will increase our understanding of the relative harm from carbonyl exposure from little and filtered cigars both for cigar-only smokers and the cumulative harm among the growing population of cigarette-cigar multi-product smokers.

Assessment of priority tobacco additives per the requirements of the EU Tobacco Products Directive (2014/40/EU): Part 1: Background, approach, and summary of findings

This paper is part of a series of 3 publications and describes the non-clinical and clinical assessment performed to fulfill the regulatory requirement per Art. 6 (2) of the EU Tobacco Products Directive 2014/40/EU; under which Member States shall require manufacturers and importers of cigarettes and roll-your-own tobacco containing an additive that is included in the priority list established by Commission Implementing Decision (EU) 2016/787 to carry out comprehensive studies. The Directive requires manufacturers and importers of cigarettes and Roll Your Own tobacco to examine for each additive whether it; contributes to and increases the toxicity or addictiveness of tobacco products to a significant or measurable degree; if it leads to a characterizing flavor of the product; if it facilitates inhalation or nicotine uptake, and if it results in the formation of CMR (carcinogenic, mutagenic and reprotoxic) constituents and if these substances increase the CMR properties of the respective tobacco product to a significant or measurable degree. This publication gives an overview on comprehensive smoke chemistry, in vitro toxicity, and human clinical studies commissioned by the members of the Priority Additives Tobacco Consortium to independent Contract Research Organizations (CROs) where the emissions of test cigarettes containing priority additives were compared to emissions emerging from an additive-free reference cigarette. Whilst minor changes in smoke chemistry parameters were observed when comparing emissions from test cigarettes with emissions from additive-free reference cigarettes, only two of the additives (sorbitol and guar gum) tested led to significant increases in a limited number of smoke constituents. These changes were not observed when sorbitol or guar gum were tested in a mixture with other priority additives. None of the priority additives resulted in increases in in vitro toxicity (Ames, Micronucleus, Neutral Red Uptake) or led to changes in smoking behavior or absorption (rate or amount) of nicotine measured during the human clinical study as compared to the additive-free reference cigarette.

Effects of Topography-Related Puff Parameters on Carbonyl Delivery in Mainstream Cigarette Smoke

Smoking topography parameters differ substantially between individual smokers and may lead to significant variation in tobacco smoke exposure and risk for tobacco-caused diseases. However, to date, little is known regarding the impact of individual puff parameters on the delivery of many harmful smoke constituents including carbonyls. To examine this, we determined the effect of altering individual puff parameters on mainstream smoke carbonyl levels in machine-smoked reference cigarettes. Carbonyls including formaldehyde, acetaldehyde, crotonaldehyde, propionaldehyde, methyl ethyl ketone (MEK), acrolein, and acetone were determined in cigarette smoke by HPLC after derivatization with 2,4-dinitrophenylhydrazine (DNPH). Deliveries of all carbonyls were nearly two-fold greater when cigarettes were smoked according to the more intense Health Canada Intense (HCI) protocol compared to the International Organization of Standardization (ISO) method, consistent with the two-fold difference in total puff volume between methods (ISO: 280-315 mL; CI: 495-605 mL). When individual topography parameters were assessed, changes in puff volume alone had the greatest effect on carbonyl delivery as predicted with total carbonyls being strongly correlated with overall puff volume (r2: 0.52-0.99) regardless of how the differences in volume were achieved. All seven of the carbonyls examined showed a similar relationship with puff volume. Minor effects on carbonyl levels were observed from vent blocking and changing the interpuff interval, while effects of changing puff duration and peak flow rate were minimal. Overall, these results highlight the importance of considering topography, especially puff volume, when the toxicant delivery and potential exposure smokers receive are assessed. The lack of an impact of other behaviors, including puff intensity and duration independent of volume, indicate that factors such as temperature and peak flow rate may have minimal overall effects on carbonyl production and delivery.

Simultaneous Determination of Furan and Vinyl Acetate in Vapor Phase of Mainstream Cigarette Smoke by GC-MS

A simple and sensitive method for simultaneous determination of furan and vinyl acetate (VA) in vapor phase of mainstream cigarette smoke with cold trap and gas chromatography-mass spectrometry (GC-MS) was developed. A Cambridge filter pad (CFP) was placed in front of the impingers of smoking machine to remove the particle phase from cigarette smoke. Furan and VA in vapor phase of mainstream cigarette smoke were collected in two impingers connected in series by filled with methanol at -78°C. The solutions were added with deuterium-labeled furan-d4 and VA-d6 as internal standards and analyzed by GC-MS. The results showed that the calibration curves for furan and VA were linear (r2 > 0.9995) over the studied concentration range. The intra- and inter-day precision values for furan and VA were <7.07% and <9.62%, respectively. The extraction recoveries of furan and VA were in the range of 94.5-97.7% and 92.3-94.9%, respectively. Moreover, the limits of detection for furan and VA were 0.028 µg mL-1 and 1.3 ng mL-1, respectively. The validated method has been successfully applied to determine the emissions of furan and VA in the vapor phase of mainstream cigarette smoke under International Organization for Standardization (ISO) and Canadian Intense (CI) smoking regimen.

A Standardized Method for the Preparation of a Gas Phase Extract of Cigarette Smoke

The gas phase of cigarette smoke is important from the viewpoint of human health, because it can pass through alveolar epithelium and enter the circulation. There is no standard method for the preparation of a gas phase extract of cigarette smoke (CSE), although CSE is widely used for research instead of whole cigarette smoke. We have established a standard method for the preparation of CSE. One cigarette per trial is continuously combusted under a reduced pressure generated by an aspiration pump with a velocity of 1.050 L/min: the main stream of the smoke is passed through a Cambridge filter to remove tar, and subsequently, bubbled through a glass ball filter (pore size, 20-30 µm) into 15 mL of phosphate-buffered saline (PBS). To express the concentration of CSE, a virtual tar concentration is introduced, which is calculated assuming that tar trapped on the Cambridge filter is dissolved in the PBS. CSEs prepared from smaller numbers of cigarettes (original virtual tar concentration≤15 mg/mL) show similar concentration-response curves for cytotoxicity versus virtual tar concentrations. CSEs prepared from various brands of cigarettes and by different smoking regimes (continuous and puff smoking) show similar cytotoxic potency if the virtual tar concentrations are the same. In conclusion, using the standardized method for CSE preparation in combination with the virtual tar concentration, it becomes possible to simply and rapidly prepare standard CSEs with defined concentrations from any brand of cigarettes, which are toxicologically equivalent to CSE prepared by puff smoking.

Considerations for comparative tobacco product assessments based on smoke constituent yields

Cigarette smoke is a complex mixture of more than 8000 smoke constituents. The quantification of selected mainstream smoke constituent yields is one of the methods to evaluating and comparing the performance of different products. Numerous regulatory and scientific advisory bodies have used cigarette smoke constituent yield data for reporting and product comparison purposes. For more than a decade limitations of the indiscriminate application of traditional statistical methods such as the t-test for differences in comparative smoke constituent yield assessments lacking a specific study design, have been highlighted. In the present study, the variability of smoke constituent yields is demonstrated with data obtained under the ISO smoking regime for the Kentucky reference cigarette 3R4F and one commercial brand, analyzed on several occasions between 2007 and 2014. Specifically it is shown that statistically significant differences in the yields of selected smoke constituents do not readily translate to differences between products, and that tolerances need to be defined. To this end, two approaches have been proposed in the literature--minimal detectable differences, and the statistical equivalence. It is illustrated how both approaches provide more meaningful comparison outcomes than the statistical t-test for differences. The present study provides considerations relevant for comparative tobacco product assessments both in the scientific and regulatory contexts.

Comparison of in vitro toxicity of mainstream cigarette smoke particulate matter from nano- to micro-size

In order to investigate the interrelationship between particulate matter (PM) size and in vitro toxicological effects of mainstream cigarette smoke, PM sized between 10 nm and 10 μm in mainstream cigarette smoke was sampled and divided into six stages. The in vitro cytotoxicity, genotoxicity and cell inhibition effects of PM were assessed by the neutral red cytotoxicity assay, Salmonella mutagenicity assay, micronucleus test and flow cytometry analysis, respectively. The results showed that all test samples were cytotoxic in the neutral red cytotoxicity assay. The IC50 values in the small-sized groups were significantly lower than those in the large-sized groups. Most test samples were mutagenic in the Salmonella mutagenicity assay (TA98 with S9 and TA100 with S9) and increased the frequency of micronucleated cells. Most PM disturbed the normal progression of the cell cycle, resulting in the accumulation of cells in the G0/G1 phase and the induction of apoptosis. In these tests, PM of a large size induced less toxicity compared with PM of a small size. These findings suggest that most PM samples induced toxicity in vitro, and PM of a small size was more toxic than PM of a large size.

Formation of mainstream cigarette smoke constituents prioritized by the World Health Organization--yield patterns observed in market surveys, clustering and inverse correlations

The WHO TobReg proposed mandating ceilings on selected smoke constituents determined from the market-specific median of nicotine-normalized yield distributions. Data validating this regulatory concept were obtained from essentially single-blend surveys. This process is strongly impacted by inverse correlations among yields. In the present study, 18 priority WHO smoke constituent yields (nicotine-normalized) were determined (using two smoking regimens) from 262 commercial brands including American, Virginia and local blends from 13 countries. Principal Component Analysis was used to identify yields patterns, clustering of blend types and the inverse correlations causing these clusters. Three principal components explain about 75% of total data variability. PC1 was sensitive to the relative levels of gas- and particle-phase compounds. PC2 and PC3 cluster American- and Virginia-blends, revealing inverse correlations: Nitrogen oxides and amino- or nitroso-aromatic compounds inversely correlate to either formaldehyde and acrolein, or benzo(a)pyrene and di-hydroxybenzenes. These results can be explained by reviewing the processes determining each components smoke delivery. Regulatory initiatives simultaneously targeting selected smoke constituents in markets with mixed blend styles will be strongly impacted by the inverse correlations described. It is difficult to predict the ultimate impact of such regulations on public health, considering the complex chemistry of cigarette smoke formation.

A comprehensive evaluation of selected components and processes used in the manufacture of cigarettes: approach and overview

CONTEXT

In addition to tobacco and cigarette ingredients, there are many non-tobacco components and processes used to manufacture commercial cigarettes. Proposed cigarette components and manufacturing process changes were evaluated using a tiered toxicological testing program.

OBJECTIVE

The toxicological testing and evaluation of proposed changes to selected non-tobacco cigarette components and manufacturing processes are described in this special report.

MATERIALS AND METHODS

Selected non-tobacco cigarette components and manufacturing processes were evaluated using experimental and control cigarettes. These experimental cigarettes were evaluated using mainstream smoke chemistry, bacterial mutagenicity and cytotoxicity assays. In some evaluations, 90-day nose-only mainstream smoke inhalation studies using rats were performed.

RESULTS

Some proposed design changes were not implemented, or limitations on their use were established. Most study results, however, were similar to those previously reported in the scientific literature for design changes in cigarette construction.

CONCLUSION

The studies reported in the series of publication demonstrate that our testing approach is feasible for evaluation of cigarette component and manufacturing process changes.

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.

Discriminatory power of standard toxicity assays used to evaluate ingredients added to cigarettes

A tiered approach for testing ingredients in a cigarette matrix was developed and includes chemical-analytical testing and a standard battery of biological toxicity assays. These assays were adapted for comparative evaluation of mainstream smoke from experimental cigarettes with or without ingredients at various inclusion levels. This adaptation to test cigarette mainstream smoke may impact assay response. Since it is difficult to a priori determine discriminatory power, it was evaluated using a large experimental dataset from a multi-year program of cigarette ingredient testing performed at two separate laboratories. A statistical method, minimum detectable difference (MDD), was used as a measure of assay discriminatory power. MDD of cigarette smoke constituents ranged from 6% to 29% of the average. Salmonella mutagenicity and cytotoxicity test MDDs ranged from 20% to 81% and 18% to 49%, respectively. Body weight gain in 90-day nose-only inhalation studies yielded an MDD of 30-40%. Histopathological findings with severity scores between 0.5 and 1.5 had the lowest MDDs of 23% and higher. In general, discriminatory power decreased with increasing biological complexity and toxicological relevance of the assay. Beyond statistical analysis, however, a weight-of-the-evidence analysis by experienced researchers is required for toxicological assessment of a cigarette ingredient.