DNA damage in human oral cells induced by use of e-cigarettes

Characterizing the Transient Emission of Particles and Gases from a Single Puff of Electronic Cigarette Smoke

This study employed high-time-resolution systems to examine the transient properties of aerosols and gases emitted from electronic cigarette (EC) puffs. Using a fast aerosol sizer, we measured particle size distributions (PSDs) across various EC brands (JUUL, VUSE, VOOPOO), revealing sizes ranging from 5 to 1000 nm at concentrations of 107 to 1010 cm-3. Most aerosols were found to be in the ultrafine range (below 100 nm), with JUUL-, VUSE-, and VOOPOO-producing aerosols with geometric mean sizes of 19.9, 47.3, and 29.4 nm, respectively. Applying the International Commission on Radiological Protection (ICRP) deposition model and assuming no further evolution of aerosols in the respiratory system, we estimated particle deposition in different respiratory regions: 45-60% in the alveolar region, 10-25% in the tracheobronchial region, and 20-35% in the extrathoracic region. The highest single-puff deposition was observed with the VOOPOO device at 60 W, depositing 180.1 ± 7.6 μg in the alveolar region. The gas emissions (CO2, NOx, CO, and total hydrocarbons) were measured at different power settings of the VOOPOO EC. Single-puff NOx and CO levels exceeded the permissible exposure limits of the Occupational Safety and Health Administration, indicating potential acute exposure risks. Higher power settings were correlated with increased gas mixing ratios, suggesting more e-liquid vaporization and possible chemical transformations at higher temperatures. These findings demonstrated significant health risks associated with ultrafine particles from high-power ECs and emphasize the need for advanced measurements to accurately assess their physicochemical properties and potential health implications.

E-cigarette: a safe tool or a risk factor for oral cancer? A systematic review

Background

Electronic cigarettes (e-cigarettes) are considered relatively safe, thus tobacco and nicotine delivery products have become popular in the last few years. However, the safety of long-term use of these products on oral health is still questionable. E-cigarettes may have potential risks to oral health that can be demonstrated as cellular damage, genetic instability, and mucosal lesions. This review aims to observe the role of e-cigarettes as a risk factor for oral cancer development.

Material and Methods

This systematic review was conducted following the PRISMA guidelines to provide reliable data on the role of electronic cigarettes as a risk factor for oral cancer development. The research was performed on Pubmed and Scopus by three reviewers from the Oral Pathology Department (Sapienza University of Rome) in May 2024. The search terms included: "e-cigarette", "oral cancer", and "risk factor" where 32 articles from PubMed and 75 from Scopus were collected. A total of 12 studies met the eligibility criteria: 6 clinical studies and 6 in vitro. All the included studies were subjected to quality assessment and data extraction processes. The risk of bias assessment of in vitro studies revealed low or unknown risk. None of the studies had any industrial sponsoring and almost all the papers (90%) had the same methods, 64% measured the cell vitality. The qualitative analysis was done for all the included clinical studies using the RoB assessment tool (MINORS). The range of the total RoB score in the comparative studies was between 12 and 23.

Results

The clinical studies involved a total of 413 participants were also included. Most studies did not specify the age and gender of participants and patients were divided into three main groups based on specific criteria: non-smokers, smokers, and e-cigarette users. These studies highlighted cases of mucosal lesions and genetic instability associated with e-cigarette use.

Conclusions

However, the limited long-term data and conflicting results emphasize the need for a larger number of studies, such as randomized controlled trials and cohort studies, to acquire more data about the safety and risks associated with e-cigarettes. Key words:E-cigarettes, squamous cell carcinoma, oral oncology, smoking.

E-Cigarette effects on oral health: A molecular perspective

Electronic cigarettes (e-cigarettes) have emerged as a potential alternative to traditional smoking and may aid in tobacco harm reduction and smoking cessation. E-cigarette use has notably increased, especially among young non-tobacco users, raising concerns due to the unknown long-term health effects. The oral cavity is the first and one of the most crucial anatomical sites for the deposition of e-cigarette aerosols. E-cigarette aerosols contain nicotine, flavors, volatile organic compounds, heavy metals, carcinogens, and other hazardous substances. These aerosols impact the oral cavity, disrupting host-microbial interactions and triggering gingivitis and systemic diseases. Furthermore, oral inflammation and periodontitis can be caused by proinflammatory cytokines induced by e-cigarette aerosols. The toxic components of e-cigarette aerosols increase the cellular reactive oxygen species (ROS) levels, reduce antioxidant capacity, increase DNA damage, and disrupt repair processes, which may further contribute to harmful effects on oral epithelum, leading to inflammatory and pre-malignant oral epithelial lesions. In this review, we analyze the toxicological properties of compounds in e-cigarette aerosols, exploring their cytotoxic, genotoxic, and inflammatory effects on oral health and delving into the underlying molecular mechanisms. Further research is essential to understand the impact of e-cigarettes on oral health and make informed regulatory decisions based on reliable scientific evidence.

Aerosolized e-liquid base constituents induce cytotoxicity and genotoxicity in oral keratinocytes

OBJECTIVE

Electronic cigarette (e-cigarette) use among adults in the United States continues to rise. Particularly concerning is the impact of e-cigarette aerosol inhalation on the oral mucosa. Aerosols are derived from a heated e-liquid base of propylene glycol/glycerin (PG/G) often mixed with nicotine and chemical flavors. Of note, harmful and potentially harmful constituents (HPHCs), including metals and volatile organic compounds, have been detected in e-cigarette aerosols. It remains unknown, however, whether aerosols exclusively derived from e-liquid PG/G are detrimental to oral keratinocytes. The present study analyzed toxicological outcomes in normal oral keratinocytes exposed to model nicotine-free, unflavored PG/G e-liquid aerosols.

MATERIALS AND METHODS

Cell viability/cytotoxicity, genotoxicity, and immunoblotting assays were conducted in NOKSI, a gingiva-derived oral keratinocyte cell line, following exposure to model e-liquid aerosols or non-aerosolized controls. The HPHC acrolein, reported to form DNA adducts in the buccal mucosa from e-cigarette users, was also used in similar assays.

RESULTS

PG/G e-liquid aerosol extracts significantly enhanced cytotoxic and DNA damaging responses in NOKSI cells when compared to non-aerosolized e-liquid treatment. Acrolein treatment led to similar results.

CONCLUSIONS

The aerosolization process of PG/G e-liquid is a critical determinant of marked cytotoxic and genotoxic stimuli in oral keratinocytes.

Oral health risks in adults who use electronic nicotine delivery systems and oral nicotine pouches: a critical review of the literature and qualitative synthesis of the available evidence

BACKGROUND

Use of combustible cigarettes (CCs) and smokeless oral tobacco products are well documented risk factors for a variety of oral diseases. However, the potential oral health risks of using recently introduced (since about 2000) non-combustible tobacco/nicotine products (NCPs: electronic cigarettes (ECs), heated tobacco products (HTPs) and oral nicotine pouches (ONPs), remain poorly established.

METHODS

This review evaluates published human studies on detrimental oral health effects in people who use NCPs compared to those smoking cigarettes and those not using any tobacco/nicotine product (NU). We identified 52 studies, predominantly focusing on adults who used electronic cigarettes as an NCP. The studies exhibited significant heterogeneity regarding design, populations, endpoints and quality. Reported outcomes, based on both single and grouped endpoints were qualitatively evaluated by comparing people who use NCPs with NU and with people smoking CCs. Significant increases (indicating a worsening in oral health), significant decreases (indicating a lower level of detrimental effects) and no significant difference between groups were assigned scores of + 1, -1 and 0, respectively. Scores from studies belonging to the same single or grouped endpoints were averaged to a summary score ranging from - 1 to + 1.

RESULTS

The qualitative meta-analysis revealed that comparisons of EC versus NU groups yielded mean scores of 0.29 for pre-cancerous lesions (N = 14 observations), 0.27 for inflammatory processes (N = 83), 0.43 for oral clinical parameters (N = 93) and 0.70 for shifts in the oral microbiome (N = 10). The corresponding values for the EC versus CC group comparisons amounted to -0.33 (N = 15), -0.14 (N = 76), -0.27 (N = 78) and 0.57 (N = 7). Most studies had significant limitations regarding group sizes, duration of NCP use (mostly only a few years) and validity of self-reported exclusive NCP use. Notably, the implications of dual use (EC + CC) and prior CC use were often not adequately considered.

CONCLUSIONS

The evaluated studies suggest that use of ECs is associated with relatively fewer detrimental oral health effects compared to smoking, yet oral health status remains poorer compared to not using any tobacco/nicotine products. These results have to be interpreted with caution due to a number of limitations and uncertainties in the underlying studies, particularly the potential biases and confounding factors inherent in cross-sectional study designs.

Effects of E-Cigarette (e-cig) Aerosols on Mutagenesis in Selected Organs in a C57 lacI (BigBlueTM) Mouse Model

The objective of this study is to investigate the potential mutagenic effects of the exposure of mice to aerosols produced from the component liquids of an electronic nicotine delivery system (ENDS). The use of electronic cigarettes (e-cigs) and ENDSs has increased tremendously over the past two decades. From what we know to date, ENDSs contain much lower levels of known carcinogens than tobacco smoke. While conventional tobacco smoke is a well-established mutagen, little is known about the mutagenicity of ENDS aerosols. Here, we report the mutagenic effects of a 3-month whole body exposure of C57 lacI mice (BigBlueTM) to filtered air (AIR) or ENDS aerosols in several tissues. Aerosols were generated from a 50/50 vegetable glycerin (VG)/propylene glycol (PG) mixture with and without nicotine. The results revealed that in the lung, bladder urothelial tissue, and tongue, mutagenesis was significantly greater in the VG/PG/nicotine group than in the AIR group. In all organs except the bladder, mutagenesis in the VG/PG only group was similar to those exposed to AIR. In the bladder, mutagenesis in the VG/PG group was elevated compared to that in the AIR group. In the liver, mutagenesis was modestly elevated in the VG/PG/nicotine group, but the elevation failed to reach statistical significance. Overall, there were no consistent differences in mutagenesis between the sexes. The results of this study suggest that exposure to e-cig aerosols containing nicotine represents a risk factor for carcinogenesis in several organ systems, and exposure to VG/PG alone may be a risk factor for bladder cancer.

Current thinking about the effects of e-cigarettes on oral cancer risk

In the last decade there has been a significant increase in the appeal and popularity of e-cigarettes. Recent national news headlines outline that one million smokers will be given a free vaping starter kit to encourage them to give up tobacco products. An independent report commissioned by the UK Government has cited promotion of vaping as a critical recommendation to ensuring England is smoke-free by 2030. Undoubtedly, the dental team will now encounter many more questions from patients keen to know more regarding the safety of electronic nicotine delivery systems and their effects on the oral cavity. However, it is often difficult to answer these questions due to a lack of evidence regarding their impact. Although there are some preliminary animal and in vitro data, additional well-designed, long-term studies are required to investigate oral health outcomes of e-cigarette use.We aim to summarise the latest evidence to better inform clinicians about the effects of vaping on oral health, particularly regarding the risks of oral cancer, so they can better inform their patients.

The use of E-cigarettes as a risk factor for oral potentially malignant disorders and oral cancer: a rapid review of clinical evidence

BACKGROUND

The popularity of e-cigarettes has increased rapidly in the last decade, particularly among teens and young adults, being advertised as a less harmful alternative to conventional tobacco products. However, in vitro and in vivo studies have evidenced a variable quantity of potentially harmful components and some recognized carcinogens which may cause DNA damage in oral cells. Additionally, evidence suggests that e-cigarettes may play active roles in the pathogenesis of other malignancies, such as lung and bladder cancers. Therefore, this rapid review aimed to assess the available clinical evidence about using e-cigarettes as a risk factor for oral potentially malignant disorders (OPMD) and oral cancer.

MATERIAL AND METHODS

A systematic search for English language articles published was performed in PubMed (MEDLINE), Embase, Scopus, and Web of Science. After the study selection process, the authors included twelve clinical studies about OPMD and oral cancer risk in e-cigarette users.

RESULTS

The main findings showed the presence of carcinogenic compounds in saliva and morphologic changes, DNA damage, and molecular pathways related to carcinogenesis in the oral cells of e-cigarette users. However, results were inconsistent compared to tobacco smokers and control groups.

CONCLUSIONS

the current clinical evidence on this topic is limited and insufficient to support using e-cigarettes as a risk factor for OPMD and oral cancer. Nevertheless, dental care professionals should advise patients responsibly about the potentially harmful effects of e-cigarettes on the oral mucosa cells. Future long-term and well-designed clinical studies are needed.

e-Cigarettes and Oral Cancer: what do we know so far?

We aim to summarise the latest evidence to better inform OMFS practitioners about the deleterious effects of vaping on oral health and the risks of oral cancer, so they can better inform their patients. Current evidence suggests that e-cigarette use is not risk-free.

The Tobacco Smoke Component, Acrolein, as a Major Culprit in Lung Diseases and Respiratory Cancers: Molecular Mechanisms of Acrolein Cytotoxic Activity

Acrolein, a highly reactive unsaturated aldehyde, is a ubiquitous environmental pollutant that seriously threatens human health and life. Due to its high reactivity, cytotoxicity and genotoxicity, acrolein is involved in the development of several diseases, including multiple sclerosis, neurodegenerative diseases such as Alzheimer’s disease, cardiovascular and respiratory diseases, diabetes mellitus and even the development of cancer. Traditional tobacco smokers and e-cigarette users are particularly exposed to the harmful effects of acrolein. High concentrations of acrolein have been found in both mainstream and side-stream tobacco smoke. Acrolein is considered one of cigarette smoke’s most toxic and harmful components. Chronic exposure to acrolein through cigarette smoke has been linked to the development of asthma, acute lung injury, chronic obstructive pulmonary disease (COPD) and even respiratory cancers. This review addresses the current state of knowledge on the pathological molecular mechanisms of acrolein in the induction, course and development of lung diseases and cancers in smokers.