Flavour chemicals, synthetic coolants and pulegone in popular mint-flavoured and menthol-flavoured e-cigarettes

Abstract

BackgroundThe Food and Drug Administration (FDA) has recently banned flavours from pod-style electronic cigarettes (e-cigarettes), except for menthol and tobacco. JUUL customers have quickly discovered that flavoured disposable e-cigarettes from other manufacturers, such as Puff, are readily available. Our goal was to compare flavour chemicals, synthetic coolants and pulegone in mint-flavoured/menthol-flavoured e-cigarettes from JUUL and Puff, evaluate the cytotoxicity of the coolants and perform a cancer risk assessment for pulegone, which is present in both JUUL pods and disposable Puff products.MethodsIdentification and quantification of chemicals were performed using gas chromatography/mass spectrometry. Cytotoxicity of the coolants was evaluated with BEAS-2B cells using the MTT 3-(4,5-dimethylthiazol-2-yl)−2,5-diphenyltetrazolium bromide assay. The cancer risk of pulegone was calculated using the margin of exposure (MOE).ResultsMenthol was the dominant flavour chemical (>1 mg/mL) in all products from both manufacturers. Minor flavour chemicals (<1 mg/mL) differed in the JUUL and Puff fluids and may produce flavour accents. The concentrations of WS-3 and WS-23 were higher in Puff than in JUUL. WS-23 was cytotoxic in the MTT assay at concentrations 90 times lower than concentrations in Puff fluids. The risk of cancer (MOE<10 000) was greater for mint than for menthol products and greater for Puff than for JUUL.ConclusionsSwitching from flavoured JUUL to Puff e-cigarettes may expose users to increased harm due to the higher levels of WS-23 and pulegone in Puff products. Cancer risk may be reduced in e-cigarettes by using pure menthol rather than mint oils to produce minty-flavoured e-cigarette products.

Electronic Cigarette Vaping Did Not Enhance the Neural Process of Working Memory for Regular Cigarette Smokers

“…In our study design, the administration parameters such as the number of cigarettes smoked, the nicotine content in r-cigs, and/or the frequency of puffing e-cigs were not controlled. Previous studies have reported the variability of the CO levels and/or nicotine concentrations depending on the frequency of puff (Trtchounian et al, 2010), the type of e-cigs (Omaiye et al, 2021), the number of puff duration (Son et al, 2020), and the duration of smoking cigarettes (Ebajemito et al, 2020). In our study, participants were allowed to smoke r-cigs or to vape e-cigs until their nicotine craving were satiated, and this might have caused the variability in the nicotine exposure.…”

Synthetic Cooling Agents in US-marketed E-cigarette Refill Liquids and Popular Disposable E-cigarettes: Chemical Analysis and Risk Assessment

“…Since these synthetic coolants are either more potent or comparable TRPM8 agonists to menthol, it is likely they facilitate inhalation in vapers using the products analyzed by us. One recent study also quantified menthol and the synthetic coolants (WS-3 and WS-23) in Puffbar devices 15 . This study (Omaiye et al,) found similar quantities of synthetic coolants and a higher quantity of menthol in the Puffbar “Cool Mint” product, and higher quantities of all 3 compounds in the “Menthol” product 15 .…”

“…One recent study also quantified menthol and the synthetic coolants (WS-3 and WS-23) in Puffbar devices 15 . This study (Omaiye et al,) found similar quantities of synthetic coolants and a higher quantity of menthol in the Puffbar “Cool Mint” product, and higher quantities of all 3 compounds in the “Menthol” product 15 . Some of these differences in amounts could be that, the tested “Cool Mint” device in this study was smaller in size (1.3 mL) than what was analyzed in Omaiye et al, study (3.2 mL).…”

“…In vitro genotoxicity studies in mammalian cells demonstrated WS-23 to be clastogenic (i.e., inducing disruption or breakages of chromosomes), leading to a call by JECFA for additional toxicological studies to further evaluate the safety of WS-23 20 . Exposure of airway-epithelial cells in-vitro to various concentrations of synthetic coolants and WS-23 containing e-liquids also demonstrated a dose-dependent cellular toxicity 15 . A recent inhalation exposure study in rodents by an E-liquid manufacturer for WS-23 determined a NOAEL of 29 mg/kg-bw (342 mg/m3) in rodents 24 .…”

“…In a recent study we demonstrated that European-marketed Juul menthol pods contained the synthetic cooling agent WS-3, while US and Canadian pods did not 14 . More recently Omaiye et al, demonstrated the presence of synthetic coolants in US-marketed disposables 15 . While synthetic cooling agents are sold to ( D o- I t- Y ourself) DIY users in the US, often under the label “Koolada”, the identity and concentrations of these agents in US-marketed E-cigarettes and E-cigarette refill liquids (“E-liquids”) remains unknown 16 .…”