Association of electronic cigarette use with lead, cadmium, barium, and antimony body burden: NHANES 2015-2016

Metal in biological samples from electronic cigarette users and those exposed to their second-hand aerosol: a narrative review

Introduction

Electronic nicotine delivery systems (ENDS) are gradually becoming more popular, particularly, among today's youth. Despite being marketed as safe by the tobacco industry, the notable absence of regulation in their composition is evident. Both the generated fluids and aerosol exhibit a wide variety of substances that are not yet fully identified. In addition to additives, the aerosol contains metals, the presence of which can be attributed to the excessive heating of metallic filaments used in vaporizing the liquid.

Objective

This review aimed to identify and describe studies that have assessed metal levels in biological samples obtained from electronic cigarette users and those exposed to their second-hand aerosol. This involved detailing the types and concentrations of metals identified and the biological samples in which the metals were detected.

Methods

Two independent researchers conducted searches in the MEDLINE and EMBASE databases to identify studies that measured the metal levels in human non-invasive biological samples from electronic cigarette users and second-hand exposure. Data were presented as a narrative review.

Results

In total, 18 articles were included in this review. Overall active and passive exposure to ENDS was related to higher levels of many metals, including lead and cadmium, in biological samples. ENDS users, in general, have lower metal concentrations in biological samples compared to the users of combustible cigarettes.

Conclusion

The exposure to primary and second-hand e-cigarette aerosol is related to higher metal concentrations in the biological samples. The adverse effects of this exposure on long-term users are yet to be determined.

Association between metal exposure from e-cigarette components and toxicity endpoints: A literature review

Electronic cigarette is often promoted and perceived as an 'healthy' alternative compared to conventional cigarettes. However, growing body of evidence indicate the possible adverse health effect associated with e-cigarette. Here we reviewed the literature with a focus on metal exposure in relation to e-cigarette use and related toxicity endpoints. Twenty-nine studies were identified for full text screening after applying the screening criteria of which 5 in vitro studies and 11 epidemiological studies were included for data extraction. Cr, Cu, Ni, Sn are the most found metal in all studies. In vitro, metal from e-cigarette (liquid or aerosols) induced cytotoxicity, oxidative stress, genotoxicity and pro-inflammatory responses. It was observed that the presence of nicotine can influence metal-induced in vitro toxicity. Based on epidemiological studies, the metal burden in e-cigarette users showed to be elevated in different populations (including e.g. NHANES). However, most often such studies were limited by the missing user characteristics, and information of other potential sources of metal exposure. In general, metals from e-cigarette use can be associated with toxicity endpoints but to uncover the metal related hazard of e-cigarette in users, more detailed data on metals in vapors and e-liquids; user habits and user demographics are needed.

Vaping, Environmental Toxicants Exposure, and Lung Cancer Risk

Lung cancer (LC) is the second-most prevalent tumor worldwide. According to the most recent GLOBOCAN data, over 2.2 million LC cases were reported in 2020, with an estimated new death incident of 1,796,144 lung cancer cases. Genetic, lifestyle, and environmental exposure play an important role as risk factors for LC. E-cigarette, or vaping, products (EVPs) use has been dramatically increasing world-wide. There is growing concern that EVPs consumption may increase the risk of LC because EVPs contain several proven carcinogenic compounds. However, the relationship between EVPs and LC is not well established. E-cigarette contains nicotine derivatives (e.g., nitrosnornicotine, nitrosamine ketone), heavy metals (including organometal compounds), polycyclic aromatic hydrocarbons, and flavorings (aldehydes and complex organics). Several environmental toxicants have been proven to contribute to LC. Proven and plausible environmental carcinogens could be physical (ionizing and non-ionizing radiation), chemicals (such as asbestos, formaldehyde, and dioxins), and heavy metals (such as cobalt, arsenic, cadmium, chromium, and nickel). Air pollution, especially particulate matter (PM) emitted from vehicles and industrial exhausts, is linked with LC. Although extensive environmental exposure prevention policies and smoking reduction strategies have been adopted globally, the dangers remain. Combined, both EVPs and toxic environmental exposures may demonstrate significant synergistic oncogenicity. This review aims to analyze the current publications on the importance of the relationship between EVPs consumption and environmental toxicants in the pathogenesis of LC.

Blood Lead Level Is Associated with Visceral Adipose Dysfunction in Patients with Type 2 Diabetes

We aimed to explore whether an elevated blood lead level (BLL) is associated with visceral adipose dysfunction in patients with type 2 diabetes mellitus (T2DM). Four thousand one hundred and fourteen diabetic participants were enrolled from seven communities in Shanghai in 2018 in the cross-sectional METAL study. BLL was measured by graphite furnace atomic absorption spectrometry. Visceral adiposity index (VAI) and lipid accumulation product (LAP)were calculated by simple anthropometric and biochemical parameters. We found that medians (IQR) of BLL were 26.0 μg/L (18.0-37.0) for men and 25.0 μg/L (18.0-35.0) for women, respectively. In men, each doubling of BLL was associated with a 2.0% higher VAI (95% CI, 0.6 to 3.5%) and 1.8% higher LAP (95% CI, 0.2 to 3.3%) after full adjustment. Using the lowest BLL quartile as the referent group, significant positive trends were observed for BLL with VAI and LAP. In women, each doubling of BLL was associated with a 1.9% higher LAP (95% CI, 0.6 to 3.1%). Additionally, there was a marginally significant positive association between BLL and VAI, either using log2-transformed concentrations as continuous variables or categorized in quartiles. In conclusion, lead exposure is associated with visceral adipose dysfunction in patients with T2DM. Further prospective studies are warranted to confirm our findings.

Smoking is associated with elevated blood level of volatile organic compounds: a population-based analysis of NHANES 2017-2018

BACKGROUND

The study aims to explore the association between cigarette smoking with blood exposure to volatile organic compounds using population data from the National Health and Nutrition Examination Survey (NHANES) 2017-2018.

METHODS

Based on the data of NHANES 2017-2018, we identified 1117 participants aged 18 to 65 years, who had complete VOCs testing data and filled out the Smoking-Cigarette Use and Volatile Toxicant questionnaires. The participants consisted of 214 dual-smoking persons, 41 E-cigarette smokers, 293 combustible-cigarette smokers and 569 non-smokers. We used One-way ANOVA and Welch's ANOVA to compare differences of VOCs concentration among 4 groups and multivariable regression model to confirm the factors associated with VOCs concentration.

RESULTS

In dual-smoking and combustible-cigarette smokers, blood concentration of 2,5-Dimethylfuran, Benzene, Benzonitrile, Furan, Isobutyronitrile were higher than non-smokers. When compared with people who never smoked, E-cigarette smokers had similar blood concentrations of VOCs. Blood concentrations of Benzene, Furan, and Isobutyronitrile were significant higher in combustible-cigarette smokers than in E-cigarette smokers. In the multivariable regression model, dual-smoking and combustible-cigarette smoking were associated with elevated blood concentrations of several VOCs except 1,4-Dichlorobenzene, while E-cigarette smoking was only associated with elevated 2,5-Dimethylfuran concentration.

CONCLUSIONS

Smoking, mainly dual-smoking and combustible-cigarette smoking, is associated with elevated blood concentration of VOCs, while the effect is weak in E-cigarette smoking.

Availability, Toxicology and Medical Significance of Antimony

Antimony has been known and used since ancient times, but its applications have increased significantly during the last two centuries. Aside from its few medical applications, it also has industrial applications, acting as a flame retardant and a catalyst. Geologically, native antimony is rare, and it is mostly found in sulfide ores. The main ore minerals of antimony are antimonite and jamesonite. The extensive mining and use of antimony have led to its introduction into the biosphere, where it can be hazardous, depending on its bioavailability and absorption. Detailed studies exist both from active and abandoned mining sites, and from urban settings, which document the environmental impact of antimony pollution and its impact on human physiology. Despite its evident and pronounced toxicity, it has also been used in some drugs, initially tartar emetics and subsequently antimonials. The latter are used to treat tropical diseases and their therapeutic potential for leishmaniasis means that they will not be soon phased out, despite the fact the antimonial resistance is beginning to be documented. The mechanisms by which antimony is introduced into human cells and subsequently excreted are still the subject of research; their elucidation will enable us to better understand antimony toxicity and, hopefully, to improve the nature and delivery method of antimonial drugs.

The Impact of the Storage Conditions and Type of Clearomizers on the Increase of Heavy Metal Levels in Electronic Cigarette Liquids Retailed in Romania

The growing popularity of electronic cigarettes has raised several public health concerns, including the risks associated with heavy metals exposure via e-liquids and vapors. The purpose of this study was to determine, using atomic absorption spectrometry, the concentrations of Pb, Ni, Zn, and Co in some commercially available e-liquid samples from Romania immediately after purchase and after storage in clearomizers. Lead and zinc were found in all investigated samples before storage. The initial concentrations of Pb ranged from 0.13 to 0.26 mg L⁻¹, while Zn concentrations were between 0.04 and 0.07 mg L⁻¹. Traces of nickel appeared in all investigated e-liquids before storage but in very small amounts (0.01–0.02 mg L⁻¹). Co was below the detection limits. We investigated the influence of the storage period (1, 3, and 5 days), storage temperature (22 °C and 40 °C), and type of clearomizer. In most cases, the temperature rise and storage period increase were associated with higher concentrations of heavy metals. This confirms that storage conditions can affect metal transfer and suggests that the temperature of storage is another parameter that can influence this phenomenon.

Relationships between ENDS-Related Familial Factors and Oral Health among Adolescents in the United States

The influence of familial and social environments plays a significant role in Electronic Nicotine Delivery System (ENDS) use and may contribute to poor oral health among adolescents. This study utilized the Population Assessment of Tobacco and Health (PATH) database and included youths aged 12 to 17 years who reported no history of dental health issues at baseline. Adjusted odds ratios (AOR) were used to examine the association between END-related familial factors and oral health among adolescents in the United States, with statistical significance set at p < 0.05. The sample consisted of 3892 adolescents (weighted N = 22,689,793). Parents’ extremely negative reaction towards ENDS when they found their children using ENDS (AOR = 0.309) was connected to a lower risk of oral health issues. The findings suggest that clinicians and policymakers need to consider the roles of these factors when developing strategies to improve oral health outcomes.

Association between Enzyme-Linked Immunosorbent Assay-Measured Kidney Injury Markers and Urinary Cadmium Levels in Chronic Kidney Disease

Cadmium exposure is associated with chronic kidney disease (CKD), but the optimal biomarker for early cadmium-associated nephrotoxicity in low-level exposure has not yet been established. We conducted a cross-sectional investigation involving 167 CKD patients stratified according to tertiles of urinary cadmium levels (UCd), in which enzyme-linked immunosorbent assay (ELISA)-measured novel renal biomarkers were utilized to assess the extent of renal injury associated with cadmium burden. In the analyses, urinary kidney injury molecule-1 (KIM-1) levels and age were the independent factors positively correlated with UCd after adjusting for covariates in non-dialysis-dependent CKD patients (high vs. low UCd, odds ratio (95% confidence interval), 1.0016 (1.0001–1.0032), p = 0.043, and 1.0534 (1.0091–1.0997), p = 0.018). Other conventional and novel renal biomarkers, such as serum creatinine, estimated glomerular filtration rate, CKD staging, urinary protein/creatinine ratio, urinary 8-hydroxy-2-deoxyguanosine (8-OHdG), and urinary epidermal growth factor (EGF) were not independently correlated with UCd in the analyses. In conclusion, our study found that the ELISA-measured urinary KIM-1 level could serve as an early renal injury marker in low-level cadmium exposure for non-dialysis-dependent CKD patients. In addition, age was an independent factor positively associated with UCd in this population.

Modification of the Peripheral Olfactory System by Electronic Cigarettes

Electronic cigarettes (e-cigs) are used by millions of adolescents and adults worldwide. Commercial e-liquids typically contain flavorants, propylene glycol, and vegetable glycerin with or without nicotine. These chemical constituents are detected and evaluated by chemosensory systems to guide and modulate vaping behavior and product choices of e-cig users. The flavorants in e-liquids are marketing tools. They evoke sensory percepts of appealing flavors through activation of chemical sensory systems to promote the initiation and sustained use of e-cigs. The vast majority of flavorants in e-liquids are volatile odorants, and as such, the olfactory system plays a dominant role in perceiving these molecules that enter the nasal cavity either orthonasally or retronasally during vaping. In addition to flavorants, e-cig aerosol contains a variety of by-products generated through heating the e-liquids, including odorous irritants, toxicants, and heavy metals. These harmful substances can directly and adversely impact the main olfactory epithelium (MOE). In this article, we first discuss the olfactory contribution to e-cig flavor perception. We then provide information on MOE cell types and their major functions in olfaction and epithelial maintenance. Olfactory detection of flavorants, nicotine, and odorous irritants and toxicants are also discussed. Finally, we discuss the cumulated data on modification of the MOE by flavorant exposure and toxicological impacts of formaldehyde, acrolein, and heavy metals. Together, the information presented in this overview may provide insight into how e-cig exposure may modify the olfactory system and adversely impact human health through the alteration of the chemosensory factor driving e-cig use behavior and product selections. © 2021 American Physiological Society. Compr Physiol 11:2621-2644, 2021.

Critical appraisal of the European Union Scientific Committee on Health, Environmental and Emerging Risks (SCHEER) Preliminary Opinion on electronic cigarettes

BACKGROUND

In preparation for the 2021 revision of the European Union Tobacco Products Directive, the Scientific Committee on Health, Environmental and Emerging Risks (SCHEER) has posted its Preliminary Opinion on Electronic Cigarettes. They concluded that e-cigarettes only achieve a sub-optimal level of protection of human health. In this paper, we provide evidence that the Opinion's conclusions are not adequately backed up by scientific evidence and did not discuss the potential health benefits of using alternative combustion-free nicotine-containing products as substitute for tobacco cigarettes.

METHODS

Searches for articles were conducted in PubMed and by citation chasing in Google Scholar. Articles were also retrieved with a review of references in major publications. Primary data from World Health Organization surveys, the conclusions of reviews, and peer-reviewed non-industry studies were cited to address errors and omissions identified in the Opinion.

RESULTS

The Opinion omitted reporting on the individual and population health benefits of the substitution of e-cigarettes (ENDS) for cigarette smoking. Alternative hypotheses to the gateway theory were not evaluated. Its assessment of cardiovascular risk is contradicted by numerous reviews. It cites ever-use data that do not represent current patterns of use. It did not report non-nicotine use. It presented erroneous statements on trends in ENDS prevalence. It over-emphasized the role of flavours in youth ENDS initiation. It did not discuss cessation in sufficient length.

CONCLUSIONS

For the delivery of a robust and comprehensive final report, the members of the Working Group of the Scientific Committee on Health, Environmental and Emerging Risks will need to consider (1) the potential health benefits of ENDS substitution for cigarette smoking, (2) alternative hypotheses and contradictory studies on the gateway effect, (3) its assessment of cardiovascular risk, (4) the measurements of frequency of use, (5) non-nicotine use, (6) the role of flavours, and (7) a fulsome discussion of cessation.