Skin contamination as pathway for nicotine intoxication in vapers

Nicotine Affects Multiple Biological Processes in EpiDermTM Organotypic Tissues and Keratinocyte Monolayers

Dermal exposure to nicotine is common due to the widespread use of tobacco products. Here, we assessed the effects of nicotine at concentrations found in thirdhand smoke (THS) contaminated environments and electronic cigarette (EC) spills or leaks on a 3D human skin model (EpiDermTM) and on submerged keratinocyte cultures. Air liquid interface treatment of EpiDermTM with 10 or 400 μg/mL of nicotine for 24 h followed by proteomics analysis showed altered pathways related to inflammation, protein synthesis, cell–cell adhesion, apoptosis, and mitochondrial function. Submerged cultured keratinocytes were used to validate the proteomics data and further characterize the response of skin cells to nicotine. Mitochondrial phenotype changed from networked to punctate in keratinocytes treated with 10 or 400 μg/mL of nicotine for 48 h and 24 h, respectively. After 72 h, all concentrations of nicotine caused a significant decrease in the networked phenotype. In Western blots, keratinocytes exposed to 400 μg/mL of nicotine had a significant decrease in mitofusin 2, while mitofusin 1 decreased after 72 h. The shift from networked to punctate mitochondria correlated with a decrease in mitofusin 1/2, a protein needed to establish and maintain the networked phenotype. Mitochondrial changes were reversible after a 24 h recovery period. Peroxisomes exposed to 400 μg/mL of nicotine for 24 h became enlarged and were fewer in number. Nicotine concentrations in THS and EC spills altered the proteome profile in EpiDermTM and damaged organelles including mitochondria and peroxisomes, which are involved in ROS homeostasis. These changes may exacerbate skin infections, inhibit wound healing, and cause oxidative damage to cells in the skin.

E-cigarette fluids and aerosol residues cause oxidative stress and an inflammatory response in human keratinocytes and 3D skin models

Our goal was to evaluate the effects of EC refill fluids and EC exhaled aerosol residue (ECEAR) on cultured human keratinocytes and MatTek EpiDerm™, a 3D air liquid interface human skin model. Quantification of flavor chemicals and nicotine in Dewberry Cream and Churrios refill fluids was done using GC-MS. The dominant flavor chemicals were maltol, ethyl maltol, vanillin, ethyl vanillin, benzyl alcohol, and furaneol. Cytotoxicity was determined with the MTT and LDH assays, and inflammatory markers were quantified with ELISAs. Churrios was cytotoxic to keratinocytes in the MTT assay, and both fluids induced ROS production in the medium (ROS-Glo™) and in cells (CellROX). Exposure of EpiDerm™ to relevant concentrations of Dewberry Cream and Churrios for 4 or 24 h caused secretion of inflammatory markers (IL-1α, IL-6, and MMP-9), without altering EpiDerm™ histology. Lab made fluids with propylene glycol (PG) or PG plus a flavor chemical did not produce cytotoxic effects, but increased secretion of IL-1α and MMP-9, which was attributed to PG. ECEAR derived from Dewberry Cream and Churrios did not produce cytotoxicity with Epiderm™, but Churrios ECEAR induced IL-1α secretion. These data support the conclusion that EC chemicals can cause oxidative damage and inflammation to human skin.

Identification and quantification of electronic cigarette exhaled aerosol residue chemicals in field sites

BACKGROUND

Electronic cigarette (EC) users may exhale large clouds of aerosol that can settle on indoor surfaces forming ECEAR (EC exhaled aerosol residue). Little is known about the chemical composition or buildup of this residue.

OBJECTIVE

Our objective was to identify and quantify ECEAR chemicals in two field sites: an EC user's living room and a multi-user EC vape shop.

METHODS

We examined the buildup of ECEAR in commonly used materials (cotton, polyester, or terrycloth towel) placed inside the field sites. Materials were subjected to different lengths of exposure. Nicotine, nicotine alkaloids, and tobacco-specific nitrosamines (TSNAs) were identified and quantified in unexposed controls and field site samples using analytical chemical techniques.

RESULTS

Nicotine and nicotine alkaloids were detected in materials inside the EC user's living room. Concentrations of ECEAR chemicals remained relatively constant over the first 5 months, suggesting some removal of the chemicals by air flow in the room approximating a steady state. ECEAR chemicals were detected in materials inside the vape shop after 6 h of exposure and levels continually increased over a month. By 1 month, the nicotine in the vape shop was 60 times higher than in the EC user's living room. ECEAR chemical concentrations varied in different locations in the vape shop. Control fabrics had either no detectable or very low concentrations of chemicals.

CONCLUSIONS

In both field sites, chemicals from exhaled EC aerosols were deposited on indoor surfaces and accumulated over time forming ECEAR. Non-smokers, EC users, and employees of vape shops should be aware of this potential environmental hazard.

Electronic cigarette chemicals transfer from a vape shop to a nearby business in a multiple-tenant retail building

BACKGROUND

Electronic cigarettes (ECs) are nicotine delivery devices that produce aerosol without combustion of tobacco; therefore, they do not produce sidestream smoke. Nevertheless, many users exhale large clouds of aerosol that can result in passive exposure of non-users. Analogous to thirdhand cigarette smoke, the exhaled aerosol also settles on indoor surfaces where it can produce a residue. We refer to this residue as EC exhaled aerosol residue (ECEAR). Our objective was to determine if exhaled EC aerosol transferred from a vape shop in a multiple-tenant retail building, where it was produced, to a nearby business (field site) where it could deposit as ECEAR.

METHODS

We examined the build-up of ECEAR in commonly used materials (cotton towel and paper towels) placed inside the field site across from the vape shop. Materials were subjected to short-term (days) and long-term (months) exposures. Nicotine, other alkaloids and tobacco-specific nitrosamines (TSNAs) were identified and quantified in controls and field site samples using analytical chemical techniques.

RESULTS

Nicotine and other alkaloids were detected after 1 day of exposure in the field site, and these chemicals generally increased as exposure times increased. TSNAs, which have been linked to carcinogenesis, were also detected in short-term and long-term exposed samples from the field site.

CONCLUSIONS

In a multiple-tenant retail building, chemicals in EC aerosol travelled from a vape shop into an adjacent business where they deposited forming ECEAR. Regulatory agencies and tenants occupying such buildings should be aware of this potential environmental hazard.

E-cigarettes: Impact of E-Liquid Components and Device Characteristics on Nicotine Exposure

BACKGROUND

Electronic cigarette (e-cigarette) use has increased substantially in recent years. While e-cigarettes have been proposed as a potentially effective smoking cessation tool, dualuse in smokers is common and e-cigarettes are widely used by non-smokers, including youth and young-adult non-smokers. Nicotine, the primary addictive component in cigarettes, is present at varying levels in many e-liquids. E-cigarettes may lead to initiation of nicotine use in adult and youth non-smokers, re-initiation of nicotine dependence in ex-smokers or increased severity of nicotine dependence in dual-users of cigarettes and e-cigarettes. As such, there are important clinical and policy implications to understanding factors impacting nicotine exposure from e-cigarettes. However, the broad and rapidly changing range of e-liquid constituents and e-cigarette hardware which could impact nicotine exposure presents a challenge. Recent changes in regulatory oversight of e-cigarettes underscore the importance of synthesizing current knowledge on common factors which may impact nicotine exposure.

METHODS

This review focuses on factors which may impact nicotine exposure by changing e-cigarette use behavior, puff topography, altering the nicotine yield (amount of nicotine exiting the e-cigarette mouth piece including nicotine exhaled as vapor) or more directly by altering nicotine absorption and bioavailability.

RESULTS

Topics reviewed include e-liquid components or characteristics including flavor additives (e.g., menthol), base e-liquid ingredients (propylene glycol, vegetable glycerin), components commonly used to dissolve flavorants (e.g., ethanol), and resulting properties of the e-liquid (e.g., pH), e-cigarette device characteristics (e.g., wattage, temperature, model) and user behavior (e.g., puff topography) which may impact nicotine exposure.

CONCLUSION

E-liquid characteristics and components, e-cigarette hardware and settings, and user behavior can all contribute substantially to nicotine exposure from e-cigarettes.