A study of pyrazines in cigarettes and how additives might be used to enhance tobacco addiction

Tobacco Constituents, Flavorants, and Paper Permeability of Factory-Made and Roll-Your-Own Cigarettes on the Australian Market

INTRODUCTION

Roll-your-own (RYO) tobacco is a popular choice in Australia, with some people who smoke finding these products more attractive than factory-made cigarettes (FMC). Differences in visual and tactile properties and in the feel and taste of the smoke may contribute to this attractiveness. These differences may be driven by variation in tobacco constituents and wrapping paper permeability. However, to date, there has been no comparison of RYO and FMC products on the Australian market.

AIMS AND METHODS

Chemical constituents, pH, flavorants, and paper permeability were compared in unburned RYO tobacco and tobacco from FMC. RYO and FMC products from matched brands were compared, as were products from the most popular FMC and RYO brands on the Australian market in 2018.

RESULTS

RYO tobacco had higher moisture and humectant content (glycerol and propylene glycol) than FMC tobacco. RYO tobacco also had higher amounts of total and reducing sugars and lower nicotine when comparing the most popular brands. RYO papers were less permeable than FMC papers. Both RYO and FMC tobacco contained many chemicals identified as flavorants, including fourteen with known potential health risks. For most measured constituents and flavorants, RYO tobaccos had more in common with other RYO than FMC, with the commonalities remaining even when matched brands were compared.

CONCLUSIONS

Higher levels of moisture, humectants, and sugars in Australian RYO tobacco compared to FMC may be increasing attractiveness of RYO by reducing the harsh taste of the smoke and increasing the moist feel of the tobacco.

IMPLICATIONS

While price is the main factor driving the use of RYO tobacco, some people who smoke find these products more attractive. This study has shown that Australian RYO tobacco contains higher amounts of glycerol, propylene glycol, and sugars than FMC. These chemicals may be improving the taste of the tobacco, as well as creating a moist feel that is falsely perceived as indicating that the tobacco is "fresh" and "less chemically." Ironically, it may be that higher amounts of some added chemicals in RYO contribute to false perceptions of a more natural and less harmful product.

Evaluation of Conventional Cardiovascular Risk Factors and Ordinal Coronary Artery Calcium Scoring in a Lung Cancer Screening Cohort

(1) Background: Lung cancer screening (LCS) consists of low-dose computed tomography (LDCT) results to reduce lung cancer-related mortality. The LCS program has a unique opportunity to impact CVD mortality by providing tools for CVD risk assessment and implementing preventative strategies. In this study, we estimated standardized CVD risk (SCORE) and assessed the prevalence of coronary artery calcium (CAC) in a Polish LCS cohort. (2) Methods: In this observational study, 494 LCS participants aged 50-79 years with a cigarette smoking history of at least 30 pack-years were included. Medical history, anthropometric measurements, blood pressure measurements, serum glucose, and cholesterol levels were assessed in one visit. CVD risk assessment using SCORE tables was performed. The results were compared to the general population (NATPOL 2011 study). On LDCT scans, CAC was classified using an Ordinal Score ranging from 0 to 12. (3) Results: The prevalence of classic cardiovascular risk factors was very high. Among study participants, 83.7% of men and 40.7% of women were classified with a very high CVD SCORE risk (>10%). CAC was reported in 190 (47%) participants. Calcification was categorized as severe (CAC ≥ 4) in 84 (21%) participants. (4) Conclusions: Due to the high cardiovascular risk, intensive preventive strategies are recommended for LCS participants.

Vesicular glutamate transporter 2 expression in the ventral tegmental area of outbred male rats following exposure to nicotine and alcohol

Background

Initiation of use/co-use of nicotine and alcohol, commonly occurring in an episodic manner during adolescence, can imprint vulnerability to the developing brain and lead to addiction. The ventral tegmental area (VTA) is a key heterogeneous region of the mesocorticolimbic circuit involved in the binge-drinking and intoxication step of the addiction circuit. Higher human post-mortem VTA expression of vesicular glutamate transporter 2 (VGLUT2), a marker of the glutamatergic phenotype also expressed in dopaminergic [Tyrosine Hydroxylase (Th)-positive] neurons, has been associated with chronic nicotine use and co-use with alcohol.

Methods

The present study aimed to map and characterize the Vglut2- and Th-expressing neurons in the VTA of adolescent male rats exposed or not to prolonged (six-weeks) episodic (three consecutive days/week) nicotine and/or alcohol administration. Nicotine (0.35 mg/kg free base) was injected subcutaneously, whereas alcohol (2 g/kg 20%) was administrated via gavage. Vglut2 and Th mRNA was assessed in the anterior and posterior VTA by use of in situ hybridization.

Results

The profile of neurons varied with substance-exposure among VTA subregions. Th-only expressing neurons were more abundant in the posterior VTA of the group exposed to nicotine-only, compared to controls. The same neurons were, on the contrary, less present in the anterior VTA of animals exposed to alcohol-only, who also displayed a higher number of Vglut2-expressing neurons in the lateral anterior VTA.

Conclusions

VTA Vglut2- and Th-only neurons seem differentially involved in the effects of adolescent episodic nicotine and alcohol exposure in the anterior and posterior VTA.

Study on volatile compounds formed from the thermal interaction of hydrolyzed vegetable proteins with reducing sugars

Hydrolyzed vegetable proteins (HVPs) are widely used food flavorings. This study investigated the volatiles formed in thermally reacted model systems containing HVPs (made from defatted soy, corn gluten, and wheat gluten) and reducing sugars (glucose and fructose). Three types of HVPs, which had different free amino acid compositions, generated qualitatively and quantitatively different volatile compounds. In the results of principal component analysis, each thermally reacted system could be distributed according to type of HVPs and sugars. Aldehydes and pyrazines highly correlated with glucose- and fructose-containing model systems, respectively. In particular, model systems containing soy HVPs showed higher contents of sugar-degraded compounds, such as maltol, furfuryl alcohol, and cyclotene. However, some Strecker aldehydes and nitrogen-containing heterocyclic compounds, whose formation required amino acids, were more abundant in model systems containing corn and wheat HVP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01194-w.

Semibiocatalytic Approach toward Regioisomerically Enriched Ethyl Dimethylpyrazines Important in Flavor Industries

Alkylpyrazines are important heterocyclic compounds used as flavorants in food and beverage industries. In this study, a regioselective semibiocatalytic process was developed to synthesize 2-ethyl-3,5-dimethylpyrazine (235-EDMP) over its 3-ethyl-2,5-dimethyl pyrazine (325-EDMP) isomer and vice versa. We initially explored how sterics could direct the coupling orientations between diamines and diketones to access 235- or 325-EDMP selectively. Also, the physical parameters of the reaction conditions were changed, such as reduced temperature, the order-of-addition of the reactants, and supplementation with chiral zeolites to template the orientation of the coupling partners to direct the reaction regiochemistry. Each reaction trial resulted in 50:50 mixtures of the EDMP isomers. An alternative approach was explored to control the regioselectivity of the reactions; α-hydroxy ketones replaced the diketones as the electrophilic coupling reactant used in previous trial experiments. The hydroxy ketone reactants were made biocatalytically with pyruvate decarboxylase. The coupling reaction between 2-hydroxypentan-3-one and propane-1,2-diamine resulted in the desired 235-EDMP at >70% (∼77 mg) relative to 325-EDMP in the mixture. The 3-hydroxypentan-2-one congener was biocatalyzed and reacted with propane-1,2-diamine as a proof of principle to synthesize 325-EDMP (∼60% relative abundance, ∼73 mg) over 235-EDMP. These results suggested a mechanism that was directed by the hydroxy ketone electrophilicity and the sterics at the diamine nucleophilic centers.

Differential Effects of 'Vaping' on Lipid and Glucose Profiles and Liver Metabolic Markers in Obese Versus Non-obese Mice

Tobacco smoking increases the risk of metabolic disorders due to the combination of harmful chemicals, whereas pure nicotine can improve glucose tolerance. E-cigarette vapour contains nicotine and some of the harmful chemicals found in cigarette smoke at lower levels. To investigate how e-vapour affects metabolic profiles, male Balb/c mice were exposed to a high-fat diet (HFD, 43% fat, 20kJ/g) for 16weeks, and e-vapour in the last 6weeks. HFD alone doubled fat mass and caused dyslipidaemia and glucose intolerance. E-vapour reduced fat mass in HFD-fed mice; only nicotine-containing e-vapour improved glucose tolerance. In chow-fed mice, e-vapour increased lipid content in both blood and liver. Changes in liver metabolic markers may be adaptive responses rather than causal. Future studies can investigate how e-vapour differentially affects metabolic profiles with different diets.

Nicotine self-administration with menthol and audiovisual cue facilitates differential packaging of CYP2A6 and cytokines/chemokines in rat plasma extracellular vesicles

In this study, we investigated whether intravenously self-administered nicotine with menthol and audiovisual cue modulates nicotine-metabolizing CYP2A6, oxidative stress modulators, and cytokines/chemokines in plasma extracellular vesicles (EVs) in rats. We assigned rats to self-administered nicotine with: (a) audiovisual cue (AV), (b) menthol, and (c) menthol and AV cue. We found increased levels of CD9 in plasma EVs after self-administered nicotine with menthol and AV cue. Moreover, expression of CYP2A6 in plasma EVs was significantly increased after self-administered nicotine in response to menthol and AV cue. However, despite an upward trend on SOD1 and catalase, increase was not found to be statistically significant, while total antioxidant capacity was found to be significantly increased in plasma and plasma EVs obtained after self-administered nicotine with menthol and AV cue. Among cytokine and chemokine profiling, we found a significant increase in the levels of MCP-1 after self-administered nicotine with menthol and AV cue and complete packaging of IL-1β in EVs. Taken together, the study provides evidence that nicotine in response to menthol and AV cues can package altered levels of CYP2A6, and cytokines/chemokines in plasma EVs that may contribute to cell–cell communication, nicotine metabolism, and inflammation upon cigarette smoking.

Is Food Addictive? A Review of the Science

As ultraprocessed foods (i.e., foods composed of mostly cheap industrial sources of dietary energy and nutrients plus additives) have become more abundant in our food supply, rates of obesity and diet-related disease have increased simultaneously. Food addiction has emerged as a phenotype of significant empirical interest within the past decade, conceptualized most commonly as a substance-based addiction to ultraprocessed foods. We detail (a) how approaches used to understand substance-use disorders may be applicable for operationalizing food addiction, (b) evidence for the reinforcing potential of ingredients in ultraprocessed foods that may drive compulsive consumptions, (c) the utility of conceptualizing food addiction as a substance-use disorder versus a behavioral addiction, and (d) clinical and policy implications that may follow if ultraprocessed foods exhibit an addictive potential. Broadly, the existing literature suggests biological and behavioral parallels between food addiction and substance addictions, with ultraprocessed foods high in both added fat and refined carbohydrates being most implicated in addictive-like eating. Future research priorities are also discussed, including the need for longitudinal studies and the potential negative impact of addictive ultraprocessed foods on children. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Effects of Inhaled Tobacco Smoke on the Pulmonary Tumor Microenvironment

Tobacco smoke is a multicomponent mixture of chemical, organic, and inorganic compounds, as well as additive substances and radioactive materials. Many studies have proved the carcinogenicity of various of these compounds through the induction of DNA adducts, mutational potential, epigenetic changes, gene fusions, and chromosomal events. The tumor microenvironment plays an important role in malignant tumor formation and progression through the regulation of expression of key molecules which mediate the recruitment of immune cells to the tumor site and subsequently regulate tumor growth and metastasis. In this chapter, we discuss the effects of inhaled tobacco smoke in the tumor microenvironment of the respiratory tract. The mechanisms underlying these effects as well as their link with tumor progression are analyzed.

Adults' favorability toward prohibiting flavors in all tobacco products in the United States

In November 2018, US Food and Drug Administration announced its intent to prohibit menthol in combustible tobacco products, prohibit flavored cigars, and prohibit flavored e-cigarettes unless they are sold in age-restricted, in-person locations. This study assessed adult attitudes toward prohibiting flavors in all tobacco products, including e-cigarettes. Data were from the 2016 Summer Styles survey of 4203 US adults aged ≥18 years. Respondents were asked whether they favored or opposed prohibiting flavors (e.g., menthol, spicy, sweet, or fruity flavor) in all tobacco products. Prevalence and correlates of favorability were assessed using weighted percentages and adjusted prevalence ratios (aPR) respectively. Assessed correlates were: sex, age, race/ethnicity, income, US Census region, marital status, children <18 years living in the home, perceptions toward e-cigarette advertising, and current (past 30-day) tobacco product use. Overall, 47.3% of adults reported favorable attitudes toward prohibiting flavors in all tobacco products. By tobacco product use status, prevalence was 52.0%, 48.4%, and 34.8% among never, former, and current users, respectively (p < .05). Among current tobacco product users, favorability was more likely among adults who believed e-cigarette ads exposure makes youth think about smoking (aPR = 1.82; 95% CI = 1.20-2.78) and those with any children aged <18 years in their household (aPR = 1.38; 95% CI = 1.05-1.82). To conclude, nearly half of adults favored prohibiting flavors in all tobacco products, including e-cigarettes. Prohibiting flavors in tobacco products could benefit public health by reducing both individual-level and population-level harms, including tobacco use initiation especially among youth.

Comparison of cigarette, little cigar, and waterpipe tobacco smoke condensate and e-cigarette aerosol condensate in a self-administration model

The pharmacological effects of tobacco products are primarily mediated by nicotine; however, research suggests that several non-nicotine tobacco constituents may alter the reinforcing effects of nicotine. This study evaluated the reinforcing effects of aqueous solutions of smoke/aerosol condensate from cigarettes, little cigars, electronic cigarettes (e-cigarettes), and waterpipe tobacco in a self-administration procedure to determine if abuse liability of these tobacco products differed. Adult male Sprague-Dawley rats (n = 64 total) were trained to self-administer intravenous nicotine (30 μg/kg/infusion) on a fixed ratio 5 schedule of reinforcement. Following nicotine dose-effect assessment (1, 7.5, 15, and 30 μg/kg/infusion), rats were given access to smoke/aerosol condensate derived from their assigned tobacco product. Rats responded for smoke/aerosol condensate containing 1, 7.5, 15, and 30 μg/kg/infusion nicotine, with the ratio of nicotine:non-nicotine constituents held constant across doses for each tobacco product. Responding for nicotine or smoke/aerosol condensate was also assessed on a progressive ratio schedule of reinforcement. Cigarette, little cigar, and e-cigarette smoke/aerosol condensates shifted the nicotine dose-effect curve leftward, whereas waterpipe tobacco smoke condensate shifted the dose-effect curve rightward. Smoke/aerosol condensate from all tobacco products produced similar levels of responding compared to nicotine alone during the progressive ratio phase. Results suggest that non-nicotine constituents in cigarettes, little cigars, and e-cigarettes differentially enhance nicotine's reinforcing potency. In contrast, waterpipe tobacco blunted nicotine's reinforcing potency, suggesting that it may contain unique constituents that dampen nicotine's reinforcing effects.

Free-Base Nicotine Is Nearly Absent in Aerosol from IQOS Heat-Not-Burn Devices, As Determined by 1H NMR Spectroscopy

Heat-not-burn products, eg, I quit ordinary smoking (IQOS), are becoming popular alternative tobacco products. The nicotine aerosol protonation state has addiction implications due to differences in absorption kinetics and harshness. Nicotine free-base fraction (α_fb) ranges from 0 to 1. Herein, we report α_fb for IQOS aerosols by exchange-averaged ¹H NMR chemical shifts of the nicotine methyl protons in bulk aerosol and verified by headspace-solid phase microextraction-gas chromatography-mass spectrometry. The α_fb ≈ 0 for products tested; likely a result of proton transfer from acetic acid and/or other additives in the largely aqueous aerosol. Others reported higher α_fb for these products, however, their methods were subject to error due to solvent perturbation.

Concentrations of nicotine, nitrosamines, and humectants in legal and illegal cigarettes in Mexico

BACKGROUND

Article 10 of the World Health Organization Framework Convention on Tobacco Control states the need for industry disclosure of tobacco contents and emissions. Currently, the profiles of key tobacco compounds in legal and illegal cigarettes are largely unknown. We aimed to analyze and compare concentrations of nicotine, nitrosamines, and humectants in legal and illegal cigarettes collected from a representative sample of smokers.

METHODS

Participants of the International Tobacco Control cohort provided a cigarette pack of the brand they smoked during the 2014 wave. Brands were classified as legal or illegal according to the Mexican legislation. Nicotine, nitrosamines, glycerol, propylene glycol, and pH were quantified in seven randomly selected packs of each brand. All analyses were done blinded to legality status. Average concentrations per brand and global averages for legal and illegal brands were calculated. Comparisons between legal and illegal brands were conducted using t tests.

RESULTS

Participants provided 76 different brands, from which 6.8% were illegal. Legal brands had higher nicotine (15.05 ± 1.89 mg/g vs 12.09 ± 2.69 mg/g; p < 0001), glycerol (12.98 ± 8.03 vs 2.93 ± 1.96 mg/g; p < 0.001), and N-nitrosanatabine (NAT) (1087.5 ± 127.0 vs 738.5 ± 338 ng/g; p = 0.006) concentrations compared to illegal brands. For all other compounds, legal and illegal brands had similar concentrations.

CONCLUSION

Compared to illegal cigarettes, legal brands seem to have higher concentrations of nicotine, NAT, and glycerol. Efforts must be made to implement and enforce Article 10 of the Framework Convention on Tobacco Control to provide transparent information to consumers, regulators, and policy-makers; and to limit cigarette engineering from the tobacco industry.

Smokers' unprompted comments on cigarette additives during conversations about the genetic basis for nicotine addiction: a focus group study

BACKGROUND

Research designed to elicit smokers' cognitive and affective reactions to information about chemicals that tobacco companies add to cigarettes ("additives") found that knowledge is limited. However, little is known about smokers' unprompted thoughts and feelings about additives. Such information could be used to shape future communication efforts. We explored the content and possible functions of spontaneous statements about cigarette additives made by smokers during a study examining reactions to learning about the genetic link to nicotine addiction.

METHODS

Adult smokers (N = 84) were recruited from a medium-sized Midwestern city. Focus groups (N = 13) were conducted between April-September 2012. Data were analyzed by 2 coders using thematic analysis.

RESULTS

Comments about cigarette additives arose without prompting by the focus group moderator. Three main themes were identified: (1) discussing additives helped participants navigate the conceptual link between smoking and genetics, (2) additives were discussed as an alternative mechanism for addiction to cigarettes, and (3) additives provided an alternative mechanism by which cigarette smoking exacerbates physical harm. Notably, discussion of additives contained a pervasive tone of mistrust illustrated by words like "they" and "them," by statements of uncertainty such as "you don't know what they're putting into cigarettes," and by negative affective verbalizations such as "nasty" and "disgusting".

CONCLUSIONS

Participants had distinct beliefs about cigarette additives, each of which seemed to serve a purpose. Although mistrust may complicate communication about the health risks of tobacco use, health communication experts could use smokers' existing beliefs and feelings to better design more effective anti-smoking messages.

Fate of pyrazines in the flavored liquids of e-cigarettes

Popularity of electronic cigarettes (ECIGs) has increased tremendously among young people, in part due to flavoring additives in ECIG liquids. Pyrazines are an important class of these additives, and their presence in tobacco cigarettes has been correlated with increased acceptability of smoking among smokers and bystanders. Pyrazine use by the tobacco industry is therefore thought to encourage smoking. However, the extent of transfer of pyrazines present in the liquid to aerosols upon vaping remains unclear. We present a simple analytical method to quantify six pyrazine derivatives in liquids and aerosols of ECIGs that allows the isolation of pyrazines from interfering compounds, like nicotine. Standard pyrazine solutions and commercial ECIG samples of different brands and flavors were tested for their pyrazine content in the liquids and in the generated aerosols from these solutions. Testing on ECIG commercial liquids revealed a heterogeneous distribution in the levels and types of pyrazines, with acetyl and alkyl pyrazines present in more than 70% of the samples. This method confirmed that pyrazine additives are common in ECIG and that labels do not usually reflect the type and quantity of pyrazines in the liquid. Pyrazines were not correlated with the nicotine content or the brand of the liquid. The aerosols showed similar pyrazine profiles to their corresponding liquids. The efficiency of transfer of pyrazines into the particle phase was approximately 46%. Therefore, addition of pyrazines to ECIGs should be regulated, because they act synergistically with nicotine to increase product appeal, ease smoking initiation, and discourage cessation.

The impact of tobacco additives on cigarette smoke toxicity: a critical appraisal of tobacco industry studies

Cigarette production involves a number of substances and materials other than just tobacco, paper and a filter. Tobacco additives include flavorings, enhancers, humectants, sugars, and ammonium compounds. Although companies maintain that tobacco additives do not enhance smoke toxicity and do not make cigarettes more attractive or addictive, these claims are questioned by independent researchers. This study reviewed the studies on the effects of tobacco additives on smoke chemistry and toxicity. Tobacco additives lead to higher levels of formaldehyde and minor changes in other smoke analytes. Toxicological studies (bacterial mutagenicity and mammalian cytoxicity tests, rat 90 days inhalation studies and bone-marrow cell micronucleus assays) found that tobacco additives did not enhance smoke toxicity. Rodent assays, however, poorly predicted carcinogenicity of tobacco smoke, and were clearly underpowered to disclose small albeit toxicologically relevant differences between test (with tobacco additives) and control (without tobacco additives) cigarettes. This literature review led to the conclusion that the impact of tobacco additives on tobacco smoke harmfulness remains unclear.

"It doesn't seem to make sense for a company that sells cigarettes to help smokers stop using them": A case study of Philip Morris's involvement in smoking cessation

BACKGROUND

In the late 1990s, American tobacco companies began offering limited cessation assistance to smokers by posting links on their company websites to government-sponsored smoking cessation resources. Philip Morris USA (PM) went further, funding youth cessation programs and creating its own online cessation program, QuitAssist. We explore why PM entered the cessation arena, and describe the variety of options considered and how PM-supported cessation programs were evaluated and promoted.

METHODS

We retrieved and analyzed archival PM documents from 1998-2005. We supplemented information from the documents with scholarly articles assessing QuitAssist and archived versions of the PM and QuitAssist websites.

RESULTS

PM's Youth Smoking Prevention department began funding youth cessation projects and programs soon after its creation in 1998, motivated by the same issue that drove its interest in youth smoking prevention: regulatory threats posed by public and policymaker concern about youth smoking. The department took a similar approach to youth smoking cessation as it did with prevention, rejecting curricula with "anti-industry" themes. In 2002, a "cessation exploration team" examined a variety of rationales for and approaches to company support for adult smoking cessation. Ultimately, PM chose QuitAssist, a limited and less expensive option that nonetheless provided opportunities for engagement with a variety of public health and government officials. Independent research indicates that QuitAssist is not an effective cessation tool.

CONCLUSIONS

While the transformation of ambitious plans into a mundane final product is a recurring theme with PM's corporate responsibility efforts, it would be inappropriate to dismiss PM's smoking cessation endeavors as half-hearted attempts to appear responsible. Such endeavors have the potential to inflict real harm by competing with more effective programs and by helping to maintain a tobacco-favorable policy environment. If PM truly wanted to support cessation, it could drop legal and other challenges to public policies that discourage smoking.