Ice flavours and non-menthol synthetic cooling agents in e-cigarette products: a review

[Harmful health effects of flavors in e-cigarettes]

BACKGROUND

Almost all e-cigarettes contain flavorings that make the product more attractive. In the evaluation of e-cigarettes on health, flavors have so far played a subordinate role.

METHOD

Selective literature search in PubMed, supplemented by legal regulations on the use of flavors in e-cigarettes.

RESULTS

Flavors make it easier to start using e-cigarettes and have a consumption-promoting effect. Deeper inhalation increases nicotine uptake and the absorption of toxic substances from the e-cigarette liquid. For some flavors, pathological effects have been demonstrated in addition to other toxic components of the e-cigarette. To date, no toxicological analyses are available for the vast majority of flavors contained in e-cigarettes.

CONCLUSIONS

The proven consumption-promoting effect and the health risks that can be extrapolated from preclinical data are significant for the political discussion of a ban on flavors for e-cigarettes, analogous to the ban on flavors in tobacco products already in force.

GC/HRMS Analysis of E-Liquids Complements In Vivo Modeling Methods and can Help to Predict Toxicity

Tobacco smoking is a major risk factor for disease development, with the user inhaling various chemicals known to be toxic. However, many of these chemicals are absent before tobacco is "burned". Similar, detailed data have only more recently being reported for the e-cigarette with regards to chemicals present before and after the e-liquid is "vaped." Here, zebrafish were dosed with vaped e-liquids, while C57-BL/6J mice were vaped using nose-cone only administration. Preliminary assessments were made using e-liquids and GC/HRMS to identify chemical signatures that differ between unvaped/vaped and flavored/unflavored samples. Oxidative stress and inflammatory immune cell response assays were then performed using our in vivo models. Chemical signatures differed, e.g., between unvaped/vaped samples and also between unflavored/flavored e-liquids, with known chemical irritants upregulated in vaped and unvaped flavored e-liquids compared with unflavored e-liquids. However, when possible respiratory irritants were evaluated, these agents were predominantly present in only the vaped e-liquid. Both oxidative stress and inflammatory responses were induced by a menthol-flavored but not a tobacco-flavored e-liquid. Thus, chemical signatures differ between unvaped versus vaped e-liquid samples and also between unflavored versus flavored e-liquids. These flavors also likely play a significant role in the variability of e-liquid characteristics, e.g., pro-inflammatory and/or cytotoxic responses.

Harm perceptions across vaping product features: An on-line cross-sectional survey of adults who smoke and/or vape in the United Kingdom

BACKGROUND AND AIMS

Vaping products are diverse with a wide variety of features, and popular products change rapidly. This study examined the features and types of vaping products that people who smoke and/or vape perceive contribute to the health harms of vaping.

DESIGN, SETTING AND PARTICIPANTS

This was a cross-sectional survey co-designed with adults who smoked/vaped and pre-registered. An on-line survey (November 2022) was used of a convenience sample of adults in the United Kingdom who smoked and/or vaped (n = 494).

MEASUREMENTS

As primary outcomes, respondents were asked to select any of 15 vaping product features they perceived might have any effect on the health harms of vaping (for each: selected, not selected). Independent variables were smoking/vaping status (smoke and vape; vape, formerly smoked; vape, never regularly smoked; smoke, do not currently vape); relative vaping harm perceptions [less harmful than smoking (accurate), equally/more harmful than smoking or do not know/refused (other)]. Binary logistic regressions were used to compare outcomes by current vaping/smoking status and relative harm perceptions, adjusting for age and sex.

FINDINGS

Most people (54.7%) selected between one and three features. The most frequently selected were nicotine concentration (62.2%) and amount of e-liquid consumed (59.1%), followed by nicotine type (e.g. salt or freebase; 33.0%), source/purchase location (25.3%), flavours (24.7%), temperature to heat e-liquid (21.1%), heat produced by device (20.9%), e-liquid brand (20.9%), amount of emissions (18.6%), device type (e.g. disposable, pod, tank; 17.2%), material of tank (17.0%), power/wattage (13.0%), device brand (8.1%), device size (4.1%) and device weight (2.4%). Higher nicotine concentrations, more e-liquid and salt (versus freebase) nicotine were perceived to confer greater harms. Disposables were perceived as slightly more harmful than reusable devices. There were few differences by current vaping/smoking status and between those with accurate (versus other) harm perceptions of vaping relative to smoking (P > 0.05 for most contrasts, adjusting for age and sex).

CONCLUSIONS

Certain features and types of vaping products [higher nicotine concentrations, more e-liquid consumed and salt (versus freebase) nicotine] were perceived to confer greater health harms among a sample of UK adults who smoked and/or vaped. Findings are consistent with pervasive misperceptions that nicotine is a major cause of harm, although e-liquid volume is likely to contribute to harms.

Labelling and composition of contraband electronic cigarettes: Analysis of products from Australia

BACKGROUND

The sale of nicotine-containing electronic cigarettes (e-cigarettes) is prescription only in Australia, regulated under the Standard for Nicotine Vaping Products (TGO110). Australian e-cigarette users, however, are purchasing e-cigarette products outside of the intended pathways.

METHODS

The labelling of e-cigarette packaging (N = 388 boxes) and the chemical composition of disposable e-cigarettes and pods (N = 428) were analysed for adherence to the current Australian regulations. These samples were confiscated from over-the-counter retailers in NSW by the NSW Ministry of Health during 2022 for non-compliance with Australian regulations.

RESULTS

Following the announcement of the prescription only model for nicotine-containing e-cigarettes in Australia in mid-2021 there was a clear shift in the labelling of products. Any mention of the word 'nicotine' was removed from e-cigarette packaging by early 2022 and nicotine warnings were replaced with generic underage sale warnings. Despite this labelling, the vast majority (98.8 %) of devices analysed contained nicotine, most (89 %) at high concentration (>30 mg/mL) and 4.2 % contained at least one chemical prohibited by the TGO110.

CONCLUSIONS

It appears that manufacturers have removed any mention of nicotine from the original packaging of nicotine-containing disposable e-cigarettes to circumvent restrictions on nicotine-containing products and continue their sale. The packaging of e-cigarette products in Australia is generally not indicative of their contents, particularly nicotine, and most did not display required warnings. Ingredients with associated health risks, prohibited in legal vapes by the TGO110, were found in samples. Consequently, the risks of e-cigarette use cannot be appropriately identified from the information supplied on the packaging or device.

Neighborhood Inequities in Tobacco Product Descriptors, Washington, DC, 2018-2019

BACKGROUND

The tobacco industry uses product descriptors to communicate reduced harm and increase appeal. This cross-sectional study assessed store-level racial, ethnic, and socioeconomic inequities in the distribution of retail tobacco product descriptors in a convenience sample of retailers in Washington, DC.

METHODS

Young adults (n = 146) who did not currently use tobacco reported real-time store visits over 14 days. Trained data collectors took high-resolution photographs of all tobacco (including e-cigarette) marketing in each store (n = 96) participants visited. We coded text descriptors on tobacco product advertisements and displays into descriptor categories (eg, fruit, sweet, concept). We fit multilevel models to examine relationships between store neighborhood census tract-level racial, ethnic, and socioeconomic characteristics and tobacco product descriptors in stores. As a supplementary analysis, we used geospatial methods to model predicted patterns of descriptors at the census tract level.

RESULTS

Stores located in census tracts with the highest versus lowest percentage of Black residents had a greater count of fruit, sweet or dessert, alcohol, and concept descriptors (p < .05), similar to findings from the geospatial approach. Adjusted models also indicated some inequities in stores in census tracts with higher percentages of Hispanic or Latino residents for fruit, alcohol, and concept descriptors; however, tract-level models showed opposite results for concept flavors.

CONCLUSIONS

In this convenience sample, fruit, alcohol, sweet/dessert, and concept FTP descriptors were prevalent in stores in neighborhoods with more Black residents demonstrated through two analytic approaches. Surveillance using representative samples of tobacco retailers could improve the ability to track the extent of this inequity.

IMPLICATIONS

We document inequities in the amount of fruit, sweet or dessert, alcohol, and concept flavor descriptors in stores across neighborhoods in Washington, DC. Federal, state, and local regulatory action is needed to reduce inequities in flavored tobacco product availability and marketing, including for concept flavors.

Development of a Flavor Ingredient Wheel Linking E-Liquid Additives to the Labeled Flavor of Vaping Products

E-liquids contain combinations of chemicals, with many enhancing the sensory attractiveness of the product. Studies are needed to understand and characterize e-liquid ingredients, particularly flavorings, to inform future research and regulations of these products. We identified common flavor ingredients in a convenience sample of commercial e-liquids using gas chromatography-mass spectrometry. E-liquid flavors were categorized by flavor descriptors provided on the product packaging. A Flavor Ingredient Wheel was developed to link e-liquid flavor ingredients with flavor categories. An analysis of 109 samples identified 48 flavor ingredients. Consistency between the labeled flavor and ingredients used to produce such flavor was found. Our novel Flavor Ingredient Wheel organizes e-liquids by flavor and ingredients, enabling efficient analysis of the link between ingredients and their flavor profiles and allowing for quick assessment of an e-liquid ingredient's flavor profile. Investigating ingredient profiles and identifying and classifying commonly used chemicals in e-liquids may assist with future studies and improve the ability to regulate these products.

Assessment of abuse liability and switching potential of menthol-flavored pod-based electronic nicotine delivery systems among US adults who smoke cigarettes

BACKGROUND

Menthol-flavored electronic nicotine delivery systems (ENDS) are a focus of public health and regulatory policy considerations. The abuse liability of five menthol-flavored pod-based ENDS was compared to combustible cigarettes, and switching potential of ENDS was also evaluated.

METHODS

215 US adults who smoke cigarettes (34.4% female; mean age[SD]=29.60[8.75]; 40.9% non-Hispanic White; mean cigarettes/day[SD]=12.04[8.52]) completed a randomized 6-arm within-person cross-over product-use study. Participants used five pod-based menthol-flavored ENDS (JUUL2 Polar Menthol 1.5%, JUUL2 Prototype Fresh Menthol 3.0%, JUUL Menthol 5.0%, Vuse Alto Menthol 5.0%, NJOY Ace Menthol 5.0%) and their usual brand (UB) cigarette for 20minutes ad libitum. After each product use, subjective reinforcing effects relevant to abuse liability and associated with switching away from cigarettes (e.g., satisfaction, product liking) were assessed.

RESULTS

All ENDS products were rated substantially and statistically significantly lower than UB cigarette on measures of subjective reinforcing effects (ps<0.001). Satisfying effects of JUUL2 1.5% were rated significantly higher than other ENDS products. JUUL2 Prototype 3.0% and Vuse Alto 5.0% did not significantly differ (ps>0.05), and both were rated significantly higher than JUUL 5.0% and NJOY Ace 5.0% (ps<0.05). Differences in subjective responses to study products did not significantly differ by preference for menthol cigarettes or by current ENDS use.

CONCLUSIONS

Abuse liability of all menthol-flavored ENDS in this study was substantially lower than combustible cigarettes. Abuse liability of JUUL2 1.5% was within the range of currently marketed pod-based menthol-flavored ENDS products. JUUL2 1.5% likely has high potential for facilitating switching among US adults who smoke.

[Harmful health effects of flavors in e-cigarettes]

BACKGROUND

 Almost all e-cigarettes contain flavorings that make the product more attractive. In the evaluation of e-cigarettes on health, flavors have so far played a subordinate role.

METHOD

 Selective literature search in PubMed, supplemented by legal regulations on the use of flavors in e-cigarettes.

RESULTS

 Flavors make it easier to start using e-cigarettes and have a consumption-promoting effect. Deeper inhalation increases nicotine uptake and the absorption of toxic substances from the e-cigarette liquid. For some flavors, pathological effects have been demonstrated in addition to other toxic components of the e-cigarette. To date, no toxicological analyses are available for the vast majority of flavors contained in e-cigarettes.

CONCLUSIONS

 The proven consumption-promoting effect and the health risks that can be extrapolated from preclinical data are significant for the political discussion of a ban on flavors for e-cigarettes, analogous to the ban on flavors in tobacco products already in force.

[Medical societies in Germany call for a ban on flavors in e-cigarettes - A Position Paper of the German Respiratory Society (DGP) in cooperation with other professional associations and organizations]

E-cigarettes are primarily used by teenagers and young adults. Flavors in e-cigarettes increase their attractiveness and encourage young people and adults to start using them. This exposes young people in particular to the risk of nicotine addiction and various toxic substances from the aerosol of e-cigarettes. There are indications that various flavors in e-cigarettes are harmful to health, although toxicological studies are still lacking for the majority of flavors. There is a need for independent scientific investigations in this area. The scientific societies involved are calling for a ban on flavors in e-cigarettes, a ban on disposable e-cigarettes, effective regulation of the sale of e-cigarettes and effective control and implementation of the provisions for the protection of minors.

Artificial Sweeteners in US-Marketed Oral Nicotine Pouch Products: Correlation with Nicotine Contents and Effects on Product Preference

Introduction

Artificial sweeteners are listed as ingredients of oral nicotine pouches (ONPs), a new product category with rapidly growing market share. The exact sweetener contents of ONPs remain unknown. Artificial sweeteners in ONPs may facilitate initiation and encourage consumption behavior.

Aims and Methods

Artificial sweetener contents in major US-marketed ONP brands (Zyn, on!, Velo) were determined by Liquid Chromatography-Mass Spectrometry (LC-MS). Sweetener effects during the initiation of ONP consumption were modeled in single- and two-bottle tests, offering mice ONP extracts calibrated to contain nicotine levels similar to saliva of people who use smokeless tobacco. To examine the contribution of sweet taste perception, consumption behavior was compared between wild-type mice and mice deficient in the sweet taste receptor (Tas1r2-/-).

Results

Acesulfame-K was detected in on!, Zyn and Velo ONPs (~0.3-0.9 mg/pouch), including products marketed as "Unflavored" or "Flavor ban approved". In Velo ONPs, sweetened with sucralose (0.6-1.2 mg/pouch), higher nicotine strength products contained higher sucralose levels. Tas1r2-/- mice consumed less ONP extracts than wild-type mice in both sexes. ONP extracts with both higher nicotine and sweetener strengths were tolerated by wild-type mice, but produced stronger aversion in Tas1r2-/- mice.

Conclusions

ONPs contain significant amounts of artificial sweeteners, with some brands adding more sweetener to ONPs with higher nicotine strengths. Artificial sweeteners, at levels present in ONPs, increase nicotine consumption. Increasing sweetener contents facilitates consumption of ONPs with higher nicotine strengths. Sweetness is a key determinant of ONP use initiation, likely reducing the aversive sensory effects of nicotine and other ONP constituents.

Implications

Artificial sweeteners such as acesulfame-K or sucralose reduce aversion and facilitate initiation and continued consumption of ONPs. The marketing of some artificially sweetened ONPs as "Unflavored" of "Flavor ban-approved" suggests that the tobacco industry rejects sweet taste as a determinant for the presence of a characterizing flavor. Sweetness as imparted by artificial sweeteners in tobacco products needs to be addressed by regulators as a component of a characterizing flavor, with the aim to reduce product appeal and initiation by never users, and especially youth attracted to sweet flavors.

An ingredient co-occurrence network gives insight into e-liquid flavor complexity

INTRODUCTION

Part of the appeal of e-cigarettes lies in their available flavors. To achieve attractive flavors, e-liquids contain many different flavoring agents, which allow many flavoring combinations. To advance our knowledge of e-liquid flavors and compositions and to evaluate the effect of legislation, we determined whether there are ingredient combinations that are frequently used together.

METHODS

We used e-cigarette ingredient data from the European Common Entry Gate system (EU-CEG) as available on 31 December 2022.

RESULTS

In e-liquids, we found 214 ingredient pairs with a co-occurrence odds ratio greater than 10. Together, these consisted of 62 unique ingredients. Network analysis revealed that ingredients were grouped together based on their flavor and/or chemical structure. We identified two densely connected regions (clusters) in the network. One consisted of six ingredients with sweet-vanilla-creamy flavors. The second cluster consisted of 13 ingredients. While some of these have fruity flavors, others, such as alkyl carboxylic acids and dimethyl sulfide, are known to have unpleasant flavors. Additional data and literature analyses indicated that alkyl carboxylic acids can contribute to a creamy and sweet-fruity taste, whereas dimethyl sulfide can contribute to a more refined fruity taste.

CONCLUSIONS

These results exemplify that the flavor of e-liquids is not just the sum of its parts. Big data analyses on product data can be used to detect such patterns, but expert knowledge and additional data are needed for further interpretation. Monitoring of e-liquid flavors as well as ingredients will remain important to regulate e-liquid product attractiveness.

Concept flavor e-cigarette unit sales in the U.S.: 2019-2022

Introduction

Concept flavor e-cigarettes, defined as products with vague/ambiguous flavor (tobacco flavor and non-tobacco flavor) names, may limit the intended impact and enforcement of flavored tobacco restrictions. This study assessed trends in unit sales of concept flavor e-cigarettes in the U.S. by volume, nicotine concentration levels (NCL), flavor and device type.

Methods

We analyzed NielsenIQ Retail Scanner point-of-sales data collected from 2182 Local Trade Areas in the contiguous 48 U.S. states and the District of Columbia aggregated weekly from August 10, 2019, through April 9, 2022. Concept flavors were categorized by: flavor type (tobacco, fruity, menthol, mint, and other); device type (pods/refillable cartridges, disposables, e-liquids, and other); and NCL (0 %-2.0 %, 2.1 %-4.0 %, > 4.1 %, unknown). Joinpoint regression was used to assess sales trends.

Results

Overall unit sales during the study period increased by 33.63 % from 1040.85 to 1390.88 thousand units per month (p = 0.006). Between August 2019 and September 2021, unit sales increased and peaked; between September 2021 and April 2022 sales decreased by 14.46 % (from 1626.02 to 1390.88 thousand units; p = 0.002). Sales of fruity, menthol and mint flavors concept flavor e-cigarettes increased by > 1000 %; disposable devices by 302.18 %; pods and refillable cartridges by 33.81 % overall; and products NCL > 4.0 % increased by 110.18 %. Tobacco flavor concept flavors (93.28 %), pods (94.63 %), and products with 2.1 %-4.0 % NCL (88.40 %) dominated unit share.

Conclusion

Sustaining the recent overall decline in the unit sales of concept flavor e-cigarettes and monitoring the sales of products with nicotine concentration greater than 2.0%, non-tobacco flavor, and pod products warrant prioritization in tobacco control efforts.

Effects of 'Ice' flavoured e-cigarettes with synthetic cooling agent WS-23 or menthol on user-reported appeal and sensory attributes

BACKGROUND

This clinical experiment tested the effects of exposure to e-cigarettes with WS-23 or menthol cooling additives on user appeal and sensory attributes, and, secondarily, whether WS-23 effects generalised across base characterising flavour, nicotine concentration, or nicotine/tobacco product use status.

METHODS

In this within-participant double-blind experiment, adult tobacco/nicotine users administered standardised puffs of 18 different e-cigarette solutions in randomised sequences using a pod-style device. Each of three base characterising e-cigarette flavour solutions ('bold tobacco', 'mango,' 'wintergreen') in both 2% and 4% concentrations of nicotine benzoate salt were manipulated by adding either: (1) Menthol (0.5%), (2) WS-23 (0.75%) or (3) No cooling agent. After each administration, participants rated 3 appeal and 5 sensory attributes (0-100 scales).

RESULTS

Participants (n=84; M(SD)=38.6 (13.6) years old) were either exclusive e-cigarette (25.0%), cigarette (36.9%) or dual (38.1%) users. WS-23 versus no coolant products produced higher liking, willingness to use again, smoothness, and coolness and lower disliking, bitterness, and harshness ratings (|B|difference range: 4.8 to 20.1; ps<0.005). Menthol (vs no coolant) increased willingness to use again and reduced harshness and coolness (ps<0.05). Flavours with WS-23 (vs menthol) were rated as smoother, cooler and less harsh (ps<0.05). Coolant effects did not differ by base flavour, nicotine concentration, or tobacco use status.

CONCLUSIONS

Adding synthetic coolant WS-23 to e-cigarettes appears to make the vaping user experience more appealing, regardless of characterising base flavour. Regulatory agencies should be aware that the manufacturing process of adding synthetic coolants may increase the attractiveness of various e-cigarette products.Cite Now.

A synthetic coolant (WS-23) in disposable electronic cigarettes impairs cytoskeletal function in EpiAirway microtissues exposed at the air liquid interface

The design of popular disposable electronic cigarettes (ECs) was analyzed, and the concentrations of WS-23, a synthetic coolant, in EC fluids were determined for 22 devices from 4 different brands. All products contained WS-23 in concentrations that ranged from 1.0 to 40.1 mg/mL (mean = 21.4 ± 9.2 mg/mL). To determine the effects of WS-23 on human bronchial epithelium in isolation of other chemicals, we exposed EpiAirway 3-D microtissues to WS-23 at the air liquid interface (ALI) using a cloud chamber that generated aerosols without heating. Proteomics analysis of exposed tissues revealed that the cytoskeleton was a major target of WS-23. BEAS-2B cells were exposed to WS-23 in submerged culture to validate the main results from proteomics. F-actin, which was visualized with phalloidin, decreased concentration dependently in WS-23 treated BEAS-2B cells, and cells became immotile in concentrations above 1.5 mg/mL. Gap closure, which depends on both cell proliferation and migration, was inhibited by 0.45 mg/mL of WS-23. These data show that WS-23 is being added to popular EC fluids at concentrations that can impair processes dependent on the actin cytoskeleton and disturb homeostasis of the bronchial epithelium. The unregulated use of WS-23 in EC products may harm human health.

Flavored Tobacco and Nicotine Use Among California Adolescents: Preferences by Use Experience and Survey Format Effects

PURPOSE

This study assessed flavored tobacco use among adolescent e-cigarette, cigarette, cigar, hookah, and smokeless tobacco users; specific e-cigarette flavor preferences; risk profiles of youth that use various flavors; and the impact of survey question wording on prevalence.

METHODS

Cross-sectional data from 4,956 California adolescent participants (aged 12-17 years) in the Teens, Nicotine, and Tobacco 2021-2022 online panel survey estimated the survey-weighted prevalence of flavored tobacco use. An embedded randomized experiment assessed survey wording effects (i.e., any vs. "usual" flavor use). Qualitative data from four contemporaneous cycles of Teens, Nicotine, and Tobacco focus groups with California adolescents (N = 63) added themes relevant to the quantitative findings.

RESULTS

88.1% of current any tobacco users reported flavored tobacco use in the past 30 days. Flavor use was lowest for cigarettes (66.7%) and highest for hookah (92.8%). Fruit was the most popular e-cigarette flavor (51.6% any use; 28.8% usual use). E-cigarette users also commonly reported use of candy and cooling flavors. Sweet flavors were used most often among adolescents otherwise at low risk of tobacco use. Survey item format did not meaningfully affect overall prevalence of flavored product use but did impact reports of specific e-cigarette flavors. Focus group participants described sweet and fruity flavors as a motivating factor in their own e-cigarette use and as designed to appeal to children.

DISCUSSION

Despite local policies, flavored tobacco use remains common among California adolescents. Survey items asking about any flavor use rather than usual use provide more information without affecting the overall prevalence of flavored tobacco use.

Public perceptions of synthetic cooling agents in electronic cigarettes on Twitter

Amid a potential menthol ban, electronic cigarette (e-cigarette) companies are incorporating synthetic cooling agents like WS-3 and WS-23 to replicate menthol/mint sensations. This study examines public views on synthetic cooling agents in e-cigarettes via Twitter data. From May 2021 to March 2023, we used Twitter Streaming API, to collect tweets related to synthetic cooling agents with keywords such as 'WS-23,' 'ice,' and 'frozen.' Two deep learning roBERTa models, classified attitudes expressed in tweets about synthetic cooling agents and identified e-cigarette users. The BERTopic deep-learning model identified major topics of positive and negative tweets. Two proportion Z-tests were used to compare the proportions of positive and negative attitudes between e-cigarette users (vapers) and non-e-cigarette-users (non-vapers). Of 6,940,065 e-cigarettes related tweets, 5,788 non-commercial tweets related to synthetic cooling agents. The longitudinal trend analysis showed a clear upwards trend in discussions. Vapers posted most of the tweets (73.05%, 4,228/5,788). Nearly half (47.87%, 2,771/5,788) held a positive attitude toward synthetic cooling agents, which is significantly higher than those with a negative attitude (19.92%,1,153/5,788) with a P-value < 0.0001. The likelihood of Vapers expressing positive attitudes (60.17%, 2,544/4,228) was significantly higher (P < 0.0001) than that from non-vapers (14.55%, 227/1,560). Conversely, negative attitudes from non-vapers (30%, 468/1,560) was significantly (P < 0.0001) higher than vapers (16.2%, 685/4,228). Prevalent topics from positive tweets included "enjoyment of specific vape flavors," "preference for lush ice vapes," and "liking of minty/icy feelings." Major topics from negative tweets included "disliking certain vape flavors" and "dislike of others vaping around them." On Twitter, vapers are more likely to have a positive attitude toward synthetic cooling agents than non-vapers. Our study provides important insights into how the public perceives synthetic cooling agents in e-cigarettes, insights that are crucial for shaping future FDA regulations aimed at safeguarding public health.

Detection of the Synthetic Coolant Menthone 1,2-Glycerol Ketal in an e-Liquid and in Electronic Waterpipe Aerosols Therefrom

The presence and toxicological risks of synthetic coolants in electronic nicotine delivery systems (ENDS) have not been thoroughly studied. We identified the synthetic coolant menthone 1,2-glycerol ketal (MGK) in a menthol-flavored e-liquid at a concentration of ∼170 μg/mL. We also detected MGK in aerosols resulting from heating the e-liquid with an electronic waterpipe. MGK was initially detected in the e-liquid by two-dimensional gas chromatography-time-of-flight mass spectrometry. To avoid potential analytical artifacts that could result from heating samples in the injection port of the gas chromatograph, quantitation of MGK in the e-liquid was accomplished using a liquid chromatography-tandem mass spectrometry method. Following recent reports identifying other synthetic coolants in e-liquids, these results add knowledge about inhalation exposures from ENDS use and suggest the importance of future research to study the potential inhalation toxicity related to the use of MGK-containing e-liquids in ENDS devices. Furthermore, the results demonstrate the ability to quantify ketals in e-liquids using liquid chromatography methods.

Still 'Cool': tobacco industry responds to state-wide menthol ban with synthetic coolants

INTRODUCTION

In December 2022, California (CA) enforced a voter-approved regulation restricting the retail sale of flavoured tobacco products, including menthol cigarettes. Shortly after, new products emerged on the market containing similar blue and green package colours yet with 'non-menthol' descriptors. Using chemical analyses, we measured the content of menthol and 15 other cooling chemicals in Californian cigarettes with 'non-menthol' descriptors and compared concentrations to similar 'menthol'-labelled counterparts available in New York State (NY).

METHODS

A convenience sample of 10 brands and types of cigarettes in CA were purchased based on package colours suggesting a cooling effect and/or 'non-menthol' descriptors. The exact brand and type of cigarettes (with menthol descriptors) were purchased in NY. Cigarettes from CA were compared with equivalent cigarettes from NY on package design and colours, cigarette physical characteristics and the presence of cooling additives.

RESULTS

Menthol was not detected in any CA cigarette, except for Maverick-green box type, while its presence was confirmed in most NY counterpart products. A synthetic cooling chemical WS-3 was not detected in any NY cigarettes but was detected in four CA brands and types with implied cooling effect, ranging from 1.24±0.04 to 1.97±0.05 mg/cigarette.

CONCLUSION

While manufacturers have removed menthol descriptors from CA packaging and the menthol ingredient from cigarettes, synthetic cooling chemicals detected in several CA brands suggest that cooling sensory effects may still be sustained. Policymakers must consider both the chemical ingredients themselves and sensory effects in future regulatory approaches.

Synthetic cooling agent in oral nicotine pouch products marketed as 'Flavour-Ban Approved'

BACKGROUND

US sales of oral nicotine pouches (ONPs) have rapidly increased, with cool/mint-flavoured ONPs the most popular flavour category. Restrictions on sales of flavoured tobacco products have either been implemented or proposed by several US states and localities. Zyn, the most popular ONP brand, is marketing Zyn Chill and Zyn Smooth as 'Flavour-Ban Approved' or 'unflavoured', probably to evade flavour bans and increase product appeal. At present, it is unclear whether these ONPs are indeed free of flavour additives that can impart pleasant sensations such as cooling.

METHODS

Sensory cooling and irritant activities of 'Flavour-Ban Approved' Zyn ONPs, Chill and Smooth, along with minty varieties (Cool Mint, Peppermint, Spearmint, Menthol), were analysed by Ca2+ microfluorimetry in HEK293 cells expressing the cold/menthol (TRPM8) or menthol/irritant receptor (TRPA1). Flavour chemical content of these ONPs was analysed by gas chromatography/mass spectrometry.

RESULTS

Zyn Chill ONP extracts robustly activated TRPM8, with much higher efficacy (39%-53%) than the mint-flavoured ONPs. In contrast, mint-flavoured ONP extracts elicited stronger TRPA1 irritant receptor responses than Chill extracts. Chemical analysis demonstrated that Chill exclusively contained WS-3, an odourless synthetic cooling agent, while mint-flavoured ONPs contained WS-3 together with mint flavourants.

CONCLUSIONS

ONP products marketed as 'Flavour-Ban Approved' or 'unflavoured' contain flavouring agents, proving that the manufacturer's advertising is misleading. Synthetic coolants such as WS-3 can provide a robust cooling sensation with reduced sensory irritancy, thereby increasing product appeal and use. Regulators need to develop effective strategies for the control of odourless sensory additives used by the industry to bypass flavour bans.

Trigeminal Function in Sino-Nasal Health and Disease

The upper airway (nasal passages, paranasal sinuses, pharynx, and glottis) provides the sentinel portion of the human respiratory tract, with the combined senses of olfaction (cranial nerve I) and trigeminal sensation (cranial nerve V) signaling the quality of inspired air. Trigeminal function also complements the sense of taste (in turn mediated by cranial nerves VII, IX and X), and participates in the genesis of taste aversions. The ability of trigeminal stimulation in the upper aero-digestive tract to trigger a variety of respiratory and behavioral reflexes has long been recognized. In this context, the last three decades has seen a proliferation of observations at a molecular level regarding the mechanisms of olfaction, irritation, and gustation. Concurrently, an ever-widening network of physiological interactions between olfaction, taste, and trigeminal function has been uncovered. The objective of this review is to summarize the relatively recent expansion of research in this sub-field of sensory science, and to explore the clinical and therapeutic implications thereof.

Appeal of e-cigarette flavors: Differences between never and ever use of combustible cigarettes

BACKGROUND

Characterizing the appeal of flavored e-cigarette solutions by tobacco product use status can inform regulations to reduce vaping in those who never smoked without discouraging adopting e-cigarettes as a quit-smoking aid.

METHODS

Adults aged 21+ who currently use tobacco products (N = 119) self-administered standardized puffs of eight non-tobacco flavored and two tobacco-flavored e-cigarette solutions using a pod-style device. Participants rated appeal (0-100 scale) following each administration. Mean differences in flavor appeal ratings were compared between four groups: people who never smoked/currently vape, formerly smoked/currently vape, currently smoke/currently vape, and currently smoke/do not vape (with interest in vaping).

RESULTS

The Global Flavor (all non-tobacco vs. tobacco)×Group interaction (p = .028) revealed higher appeal for non-tobacco vs. tobacco flavors in adults who never smoked/currently vape (B[95 %CI] = 13.6[4.1-23.1]), formerly smoked/currently vape (B[95 %CI] = 11.6[4.2-18.9]), and currently smoke/currently vape (B[95 %CI] = 9.3[2.5-11.6]), but not adults who currently smoke/never vaped (B[95 %CI] = -0.1[-5.1 to 4.9]). In flavor-specific analyses, adults who never smoked/currently vape rated strawberry (p = .022), peppermint (p = .028), and menthol (p = .028) more appealing than tobacco flavors. Among adults who formerly smoked/currently vape, strawberry (p < .001), peppermint (p = .009), and vanilla (p = .009), were more appealing than tobacco. Adults who currently smoked/currently vape rated peppermint (p = .022) and vanilla (p = .009) as more appealing than tobacco. No non-tobacco flavors were more appealing than tobacco in adults who currently smoke/never vaped.

CONCLUSIONS

E-cigarette sales restrictions on non-tobacco flavors, including menthol, may eliminate products preferred by adults who vape, including those who never smoked, without discouraging adults who currently smoke and never vaped from trying e-cigarettes.

Predictors of Discontinued E-Cigarette Use at One-Year Follow-Up in a Sample of Young Adults

BACKGROUND

Currently, the research on factors associated with young adults' discontinuation of e-cigarette use behavior is limited. This study tested the predictors of self-reported e-cigarette abstinence at one-year follow-up among young adult baseline current e-cigarette users. The following variables were tested as predictors: demographics, cigarette smoking, e-cigarette use dependence, e-cigarette use duration, harm perceptions, and preferred aspects of e-cigarette use, including sensations, flavor, and device characteristics.

METHODS

Data were provided at two time-points one year apart by 435 ethnically diverse young adults (M age = 22.3, SD = 3.1; 63% women) who reported current e-cigarette use at baseline.

RESULTS

Approximately 42% of those who reported current e-cigarette use at baseline (i.e., 184 out of 435 participants) reported discontinuation of e-cigarette use at one-year follow-up. Results indicated that higher e-cigarette dependence, longer history of e-cigarette use, lower e-cigarette harm perceptions, greater preference for both menthol and sweet flavors, for open-pod-based devices, and for e-cigarette use sensations such as buzz, taste and smell of flavors, and throat hit at baseline were associated with lower likelihood of e-cigarette use discontinuation at one-year follow-up.

CONCLUSIONS

Characteristics associated with nicotine (e.g., dependence) and flavors (e.g., taste and smell) appear to drive the continuation/discontinuation of e-cigarette use among young adults. Thus, cessation strategies may need to be developed with a focus on dependence and harm perceptions related to nicotine and flavors. Furthermore, better regulating open-pod-based devices and sweet-menthol flavors may help e-cigarette use prevention.

Synthetic Cooling Agent in Oral Nicotine Pouch Products Marketed as "Flavor-Ban Approved"

Background

US sales of oral nicotine pouches (ONPs) have rapidly increased, with cool/mint-flavored ONPs the most popular. Restrictions on sales of flavored tobacco products have either been implemented or proposed by several US states and localities. Zyn, the most popular ONP brand, is marketing Zyn-"Chill" and Zyn-"Smooth" as "Flavor-Ban Approved", probably to evade flavor bans. At present it is unclear whether these ONPs are indeed free of flavor additives that can impart pleasant sensations such as cooling.

Methods

Sensory cooling and irritant activities of "Flavor-Ban Approved" ONPs, Zyn-"Chill" and "Smooth", along with "minty" varieties (Cool Mint, Peppermint, Spearmint, Menthol), were analyzed by Ca2+ microfluorimetry in HEK293 cells expressing the cold/menthol (TRPM8) or menthol/irritant receptor (TRPA1). Flavor chemical content of these ONPs was analyzed by GC/MS.

Results

Zyn-"Chill" ONP extracts robustly activated TRPM8, with much higher efficacy (39-53%) than the mint-flavored ONPs. In contrast, mint-flavored ONP extracts elicited stronger TRPA1 irritant receptor responses than Zyn-"Chill" extracts. Chemical analysis demonstrated the presence of WS-3, an odorless synthetic cooling agent, in Zyn-"Chill" and several other mint-flavored Zyn-ONPs.

Conclusions

Synthetic cooling agents such as WS-3 found in 'Flavor-Ban Approved' Zyn-"Chill" can provide a robust cooling sensation with reduced sensory irritancy, thereby increasing product appeal and use. The label "Flavor-Ban Approved" is misleading and may implicate health benefits. Regulators need to develop effective strategies for the control of odorless sensory additives used by the industry to bypass flavor bans.

E-cigarette Flavors, Sensory Perception, and Evoked Responses

The chemosensory experiences evoked by flavors encompass a number of unique sensations that include olfactory stimuli (smell), gustatory stimuli (taste, i.e., salty, sweet, sour, bitter, and umami (also known as "savoriness")), and chemesthesis (touch). As such, the responses evoked by flavors are complex and, as briefly stated above, involve multiple perceptive mechanisms. The practice of adding flavorings to tobacco products dates back to the 17th century but is likely much older. More recently, the electronic cigarette or "e-cigarette" and its accompanying flavored e-liquids emerged on to the global market. These new products contain no combustible tobacco but often contain large concentrations (reported from 0 to more than 50 mg/mL) of nicotine as well as numerous flavorings and/or flavor chemicals. At present, there are more than 400 e-cigarette brands available along with potentially >15,000 different/unique flavored products. However, surprisingly little is known about the flavors/flavor chemicals added to these products, which can account for >1% by weight of some e-liquids, and their resultant chemosensory experiences, and the US FDA has done relatively little, until recently, to regulate these products. This article will discuss e-cigarette flavors and flavor chemicals, their elicited responses, and their sensory effects in some detail.

Non-Targeted Chemical Characterization of JUUL-Menthol-Flavored Aerosols Using Liquid and Gas Chromatography

The aerosol constituents generated from JUUL Menthol pods with 3.0% and 5.0% nicotine by weight (Me3 and Me5) are characterized by a non-targeted approach, which was developed to detect aerosol constituents that are not known to be present beforehand or that may be measured with targeted methods. Three replicates from three production batches (n = 9) were aerosolized using two puffing regimens (intense and non-intense). Each of the 18 samples were analyzed by gas chromatography electron ionization mass spectrometry and by liquid chromatography electrospray ionization high-resolving power mass spectrometry. All chemical constituents determined to differ from control were identified and semi-quantified. To have a complete understanding of the aerosol constituents and chemistry, each chemical constituent was categorized into one of five groups: (1) flavorants, (2) harmful and potentially harmful constituents, (3) leachables, (4) reaction products, and (5) chemical constituents that were unable to be identified or rationalized (e.g., chemical constituents that could not be categorized in groups (1–4). Under intense puffing, 74 chemical constituents were identified in Me3 aerosols and 68 under non-intense puffing, with 53 chemical constituents common between both regimens. Eighty-three chemical constituents were identified in Me5 aerosol using an intense puffing regimen and seventy-five with a non-intense puffing regimen, with sixty-two chemical constituents in common. Excluding primary constituents, reaction products accounted for the greatest number of chemical constituents (approximately 60% in all cases, ranging from about 0.05% to 0.1% by mass), and flavorants—excluding menthol—comprised the second largest number of chemical constituents (approximately 25%, ranging consistently around 0.01% by mass). The chemical constituents detected in JUUL aerosols were then compared to known constituents from cigarette smoke to determine the relative chemical complexities and commonalities/differences between the two. This revealed (1) a substantial decrease in the chemical complexity of JUUL aerosols vs. cigarette smoke and (2) that there are between 55 (Me3) and 61 (Me5) unique chemical constituents in JUUL aerosols not reported in cigarette smoke. Understanding the chemical complexity of JUUL aerosols is important because the health effects of combustible cigarette smoke are related to the combined effect of these chemical constituents through multiple mechanisms, not just the effects of any single smoke constituent.

Expanding the E-Liquid Flavor Wheel: Classification of Emerging E-Liquid Flavors in Online Vape Shops

INTRODUCTION

Electronic cigarettes are the most popular tobacco product among U.S. youth, and over 80% of current youth users of e-cigarettes use flavored e-cigarettes, with fruit, mint/menthol, and candy/sweets being the most popular flavors. A number of new e-liquid flavors are currently emerging in the online e-cigarette market. Menthol and other flavored e-cigarettes could incentivize combustible tobacco smokers to transition to e-cigarette use.

METHODS

From February to May 2021, we scraped data of over 14,000 e-liquid products, including detailed descriptions of their flavors, from five national online vape shops. Building upon the existing e-liquid flavor wheel, we expanded the semantic databases (i.e., key terms) to identify flavors using WordNet-a major database for keyword matching and group discussion. Using the enriched databases, we classified 14,000+ e-liquid products into the following 11 main flavor categories: "fruit", "dessert/candy/sweets", "coffee/tea", "alcohol", "other beverages", "tobacco", "mint/menthol", "nuts", "spices/pepper", "other flavors", and "unspecified flavor".

RESULTS

We find that the most prominent flavor sold in the five online vape shop in 2021 was fruit flavored products, followed by dessert/candy/other sweets. Online vendors often label a product with several flavor profiles, such as fruit and menthol.

CONCLUSIONS

Given that online stores market products with multiple flavor profiles and most of their products contain fruit flavor, the FDA may have issued marketing denial orders to some of these products. It is important to further examine how online stores respond to the FDA flavor restrictions (e.g., compliance or non-compliance).

E-Cigarettes Reexamined: Product Toxicity

The introduction of e-cigarettes, or electronic nicotine delivery systems (ENDS), has been accompanied by controversy regarding their safety and effectiveness as a cessation aid and by an explosion in their use by youth. Their use does not involve the combustion of tobacco and the creation of harmful combustion products; they have been seen as a "harm reduction" tool that may be of assistance in promoting smoking cessation. Recognition that ENDS can deliver an array of chemicals and materials with known adverse consequences has spurred more careful examination of these products. Nicotine, nitrosamines, carbonyl compounds, heavy metals, free radicals, reactive oxygen species, particulate matter, and "emerging chemicals of concern" are among the constituents of the heated chemical aerosol that is inhaled when ENDS are used. They raise concerns for cardiovascular and respiratory health that merit the attention of clinicians and regulatory agencies. Frequently cited concerns include evidence of disordered respiratory function, altered hemodynamics, endothelial dysfunction, vascular reactivity, and enhanced thrombogenesis. The absence of evidence of the consequences of their long-term use is of additional concern. Their effectiveness as cessation aids and beneficial impact on health outcomes continue to be examined. It is important to ensure that their production and availability are thoughtfully regulated to optimise their safety and permit their use as harm reduction devices and potentially as smoking-cessation aids. It is equally vital to effectively prevent them from becoming ubiquitous consumer products with the potential to rapidly induce nicotine addiction among large numbers of youth. Clinicians should understand the nature of these products and the implications of their use.

E-Taste: Taste Sensations and Flavors Based on Tongue’s Electrical and Thermal Stimulation

Taste is a key sense that helps identify different food types and most of this work was carried out on primary tastes rather than generating different flavors. In this work, we proposed a plan to create other flavors rather than primary tastes, adjusted the electrical (40–180 µA) and thermal stimulation (20–38 °C and 38–20 °C), and revealed the digital coding for multi-flavors. Our results showed that different combinations of digital coding could generate different flavors and that tastes related to different stimuli are easy to develop. The novelty of this work is to design other types of flavors and primary tastes. The experimental results demonstrated that the novel method proposed for digital taste coding could realize primary tastes (sweet, sour, salty, spicy, and mint) and mixed flavors. Furthermore, some innovative sensations have been realized, which are sprite, soda water, sweet-sour, salty-sweet, and salty-mint sensations. We presume that this innovation could digitally enhance various flavors.