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The use of electronic nicotine delivery systems, such as e-cigarettes and heated tobacco products (HTPs), is increasing, but knowledge of their short and long-term toxicological effects remains limited. Here, aerosols generated from an e-cigarette using a flavour-free e-liquid base, both with and without nicotine, an HTP, and a conventional cigarette were characterised for the production of polycyclic aromatic hydrocarbons (PAHs), carbonyls and volatile organic compounds (VOCs). Furthermore, extracts from vapour and smoke were generated, and their acute toxicity was assessed in human lung epithelial cells and fibroblasts. Cigarette smoke contained significantly more toxic compounds and induced the highest degree of toxicity in all the tested cell lines, followed by the HTP, and then the nicotine containing e-cigarette. Notably, the nicotine containing e-cigarette produced similar levels of formaldehyde as the HTP and cigarette smoke, and caused a greater decrease in cell viability in primary lung fibroblasts compared to the nicotine-free e-cigarette. Although the HTP aerosol contained lower levels of toxicants than cigarette smoke, some VOCs specific to HTPs were detected. More independent research is needed to identify toxicant-specific production in emerging nicotine delivery systems and their potential health impacts to better inform policy makers, health care providers and the general public.

Background: Cigarette smoking stands as one of the leading causes of preventable death globally. Alternative tobacco products, such as e-cigarettes, have gained popularity due to the general perception of being less harmful. However, much is still unknown about the health implications of these novel products. In this study, we aimed to investigate if e-cigarettes could induce pulmonary inflammatory responses by measuring lung-related circulating extracellular vesicles (EVs) in the blood of healthy volunteers following brief e-cigarette vaping sessions, with and without nicotine.

Methods: 22 healthy volunteers were included. Employing a randomized, double-blind, cross-over design all participants vaped 30 puffs of e-cigarette aerosol, with and without nicotine, over a 30-min period. Blood samples were collected at baseline, 30- and 105-min following exposure. Lung-related EVs were quantified using flow cytometry. Analyzed markers included angiotensin converting enzyme (ACE), aldehyde dehydrogenase 3B1 (ALDH3B1), palate, lung and epithelial clone (PLUNC), complement component 3 (C3), C-C motif chemokine ligand 3 (CCL3), also known as macrophage inflammatory protein 1 alpha (MIP-1α), and uteroglobin, also known as club cell protein 16 (CC16). All these markers are associated with pulmonary inflammation.

Results: E-cigarette use, with nicotine but not without, resulted in a significant increase in three out of the six lung-related inflammatory markers measured and clear increases though not statistically significant in the remaining three.

Conclusion: The observed increase in levels of circulating lung-related inflammatory EV markers following vaping e-cigarette aerosol containing nicotine suggests that inhaled nicotine plays a central role in triggering pulmonary inflammation. Clinicaltrials.gov ID: NCT04175457.

Background: The use of alternative and renewable fuels in the transport sector is growing rapidly due to increasing demand for sustainable energy solutions, however implying an increased risk for human exposure to emissions from these new fuels.

Methods: In this study, we examined the effects on BEAS-2B cells of particulate matter (PM) emissions, derived from the use of petroleum diesel (SD10) and rapeseed methyl ester (RME100) in a truck engine. We assessed several endpoints, including the induction of apoptotic and necrotic cell death, reactive oxygen species generation inside cells, inflammatory response, and cell cycle alterations.

Results: The characteristics of the exhaust PM varied between the two fuels, where the RME100-derived PM contained lower levels of polycyclic aromatic hydrocarbons and elemental carbon compared to SD10. Toxicological analyses revealed that PM from RME100 induced weaker oxidative stress and cell death responses than SD10. However, unlike SD10, RME100 PM caused a notable arrest in the S-G2/M phase of the cell cycle.

Conclusions: In summary, fuel type clearly influenced the characteristics of PM emissions from a heavy-duty diesel engine, which in turn affected the particles’ biological activity. Overall, RME100 exhaust PM exhibited lower toxicity compared to petroleum diesel PM in the BEAS-2B cell model.

The advent of heated tobacco products (HTPs) has introduced new variables in the study of nicotine delivery systems and their health implications. Amidst concerns over cardiovascular effects, this study aims to elucidate the acute impact of HTP inhalation on extracellular vesicles (EV) levels in young, healthy individuals. In this controlled, acute exposure study, 23 young, healthy volunteers were subjected to HTP inhalation. EV levels of endothelial and platelet origin were quantified through flow cytometry before and after exposure. Data analysis was performed using multiple measures ANOVA to assess changes in EV concentrations. Our findings reveal a significant increase in EVs of endothelial and platelet origin following short-term HTP inhalation with nicotine. Notably, no significant change was observed in leukocyte- and neutrophil-derived EVs. This increase in EVs suggests acute vascular stress, with peak levels observed 4 h post-exposure. The rise in endothelial and platelet-derived EVs aligns with documented responses to acute vascular injury, paralleling the effects seen with traditional cigarette and e-cigarette use. Despite HTPs being marketed as safer alternatives, our results indicate that nicotine-containing HTPs may still pose significant vascular risks. These findings contribute to the growing body of evidence cautioning against the perceived safety of HTPs and reinforce the importance of regulatory oversight and public health initiatives targeting nicotine delivery technologies. Trial Registrations: ClinicalTrials.gov ID: NCT04824495, registered 2021–01-07.

Background: Exposure to standard petrodiesel exhaust is linked to adverse health effects. Moreover, there is a mounting request to replace fossil-based fuels with renewable and sustainable alternatives and, therefore, rapeseed methyl ester (RME) and other biofuels have been introduced. However, recent toxicological research has indicated that biodiesel exhaust may also induce adverse health-related events.

Aim: To determine whether exposure to 100% RME biodiesel (BD100) exhaust would cause an acute airway neutrophilic recruitment in humans.

Methods: Fourteen healthy subjects underwent exposure to diluted BD100 exhaust and filtered air for 1-h, in a blinded, random fashion. Bronchoscopy with endobronchial mucosal biopsies, bronchial wash (BW) and bronchoalveolar lavage (BAL) was performed six hours after exposure. Differential cell counts and inflammatory markers were determined in the supernatant and biopsies were stained immunohistochemically.

Results: Compared with filtered air, BD100 exhaust exposure increased bronchial mucosal endothelial P-selectin adhesion molecule expression, as well as neutrophil, mast cell and CD68 + macrophage numbers. An increased influx of neutrophils and machrophages was also seen in BW.

Conclusion: Exposure to biodiesel exhaust was associated with an acute airway inflammation that appeared similar to preceding petrodiesel exposure studies. The present findings, together with the recently reported adverse cardiovascular effects after similar biodiesel exposure, indicate that biodiesel is not free of toxicity and may affect human health.

In urban areas, inhalation of fine particles from combustion sources such as diesel engines causes adverse health effects. For toxicity testing, a substantial amount of particulate matter (PM) is needed. Conventional sampling involves collection of PM onto substrates by filtration or inertial impaction. A major drawback to those methodologies is that the extraction process can modify the collected particles and alter their chemical composition. Moreover, prior to toxicity testing, PM samples need to be resuspended, which can alter the PM sample even further. Lastly, the choice of the resuspension medium may also impact the detected toxicological responses. In this study, we compared the toxicity profile of PM obtained from two alternative sampling systems, using in vitro toxicity assays. One system makes use of condensational growth before collection in water in an impinger – BioSampler (CG-BioSampler), and the other, a Dekati® Gravimetric Impactor (DGI), is based on inertial impaction. In addition, various methods for resuspension of DGI collected PM were compared. Tested endpoints included cytotoxicity, formation of cellular reactive oxygen species, and genotoxicity. The alternative collection and suspension methods affected different toxicological endpoints. The water/dimethyl sulfoxide mixture and cell culture medium resuspended particles, along with the CG-BioSampler sample, produced the strongest responses. The water resuspended sample from the DGI appeared least toxic. CG-BioSampler collected PM caused a clear increased response in apoptotic cell death. We conclude that the CG-BioSampler PM sampler is a promising alternative to inertial impaction sampling.

The use of alternative diesel fuels has increased due to the demand for renewable energy sources. There is limited knowledge regarding the potential health effects caused by exhaust emissions from biodiesel- and renewable diesel-fueled engines. This study investigates the toxic effects of particulate matter (PM) emissions from a diesel engine powered by conventional petroleum diesel fuel (SD10) and two biodiesel and renewable diesel fuels in vitro. The fuels used were rapeseed methyl ester (RME), soy methyl ester (SME), and Hydrogenated Vegetable Oil (HVO), either pure or as 50% blends with SD10. Additionally, a 5% RME blend was also used. The highest concentration of polycyclic aromatic hydrocarbon emissions and elemental carbon (EC) was found in conventional diesel and the 5% RME blend. HVO PM samples also exhibited a high amount of EC. A dose-dependent genotoxic response was detected with PM from SD10, pure SME, and RME as well as their blends. Reactive oxygen species levels were several times higher in cells exposed to PM from SD10, pure HVO, and especially the 5% RME blend. Apoptotic cell death was observed in cells exposed to PM from SD10, 5% RME blend, the 50% SME blend, and HVO samples. In conclusion, all diesel PM samples, including biodiesel and renewable diesel fuels, exhibited toxicity.

Background and aims: Heated tobacco products (HTPs) are novel alternative tobacco products being promoted as an alternative to cigarettes. To evaluate the impact of HTP use on vascular function, we investigated the effects of a brief HTP usage on arterial stiffness and platelet thrombus formation in healthy volunteers.

Methods: In a randomised crossover study, twenty-four healthy young adults with occasional tobacco use smoked the HTP IQOS 3 Multi (Phillip Morris Int.) and “no-exposure” was used as a control, with a wash-out period of at least one week in-between. Arterial stiffness was assessed through pulse wave velocity and pulse wave analysis. Blood samples, collected at baseline and 5 min following exposure, were analysed with the Total-Thrombus-formation analysis system evaluating platelet and fibrin-rich thrombus formation tendency.

Results: HTP exposure caused immediate heightened pulse wave velocity (+0.365 m/s, 95% CI: +0.188 to 0.543; p = 0.004) and enhanced augmentation index corrected to heart rate (+6.22%, 95% CI: +2.33 to 10.11; p = 0.003) compared to the no-exposure occasion. Similarly, blood pressure and heart rate transiently increased immediately following HTP inhalation. Platelet thrombus formation significantly increased following HTP exposure (area under the curve +59.5, 95% CI: +25.6 to 93.4; p < 0.001) compared to no-exposure. No effect was seen on fibrin-rich thrombus formation following HTP-exposure.

Conclusions: Brief HTP use in healthy young adults had immediate adverse effects on vascular function resulting in increased arterial stiffness and platelet thrombus formation, known risk factors for the development of atherosclerosis. Further research is needed to address long term health impacts.

Electronic cigarette (EC) vaping is increasingly popular, despite growing evidence of adverse health effects. To further evaluate the impact of EC use on vascular health, we investigated the effects of brief EC inhalation on flow-dependent thrombus formation and microcirculation in healthy volunteers. The study was performed with a randomised double-blind crossover design. Twenty-two healthy subjects aged between 18 and 45 years with occasional tobacco use were recruited. Subjects inhaled 30 puffs of EC aerosol with and without nicotine on two occasions separated by a wash-out period of at least 1 week. Blood samples were collected at baseline and at 15 and 60 min following exposure and analysed with the Total-Thrombus-formation analysis system evaluating fibrin-rich thrombus formation and platelet thrombus formation in whole blood under flow. Microvascular function was assessed at baseline and 30 min after exposure by laser speckle contrast imaging and iontophoresis of acetylcholine and sodium nitroprusside (SNP) to evaluate the endothelium-dependent and independent pathways of vasodilation. Compared with nicotine free EC aerosol, exposure to EC aerosol with nicotine significantly increased platelet thrombus formation and fibrin-rich thrombus formation at 15 min (p = 0.017 and p = 0.037, respectively) with normalisation after 60 min. Peak SNP-mediated microvascular perfusion, i.e. endothelium-independent vasodilation, was reduced following EC vaping with nicotine compared with baseline (p = 0.006). Thirty puffs of EC aerosol with nicotine increased platelet and fibrin-dependent thrombus formation and reduced microvascular dilatation capacity. No compelling effects of EC vaping without nicotine were observed, indicating nicotine as the main effector.

Trial registration: ClinicalTrials.gov Identifier: NCT04175457 URL: https://clinicaltrials.gov/ct2/show/NCT04175457.

Background: Snus usage is commonly touted as a safer alternative to cigarette smoking. However, recent studies have demonstrated possible adverse cardiovascular effects in chronic snus users. The present study evaluates the effects of chronic snus use on vascular function by assessing central arterial stiffness and endothelial vasodilatory function in healthy chronic snus users as compared to matched non-users.

Methods and results: Fifty healthy males (24 snus users, 26 age-matched controls) with a mean age of 44 years were included in the study. Arterial stiffness was assessed employing both pulse wave velocity and pulse wave analysis. Endothelial vasodilatory function was measured by venous occlusion plethysmography, utilizing intra-arterial administration of acetylcholine, glyceryl trinitrate and bradykinin to further gauge endothelium-dependent and -independent vasodilatory function. Arterial stiffness was significantly higher in chronic snus users as compared to controls: pulse wave velocity [m/s]: 6.6±0.8 vs 7.1±0.9 resp. (p = 0.026), augmentation index corrected for heart rate [%]: 0.1±13.2 vs 7.3±7.8 resp. (p = 0.023). Endothelial independent vasodilation, i.e. the reaction to glyceryl trinitrate, was significantly lower in snus users as measured by venous occlusion plethysmography.

Conclusions: The results of this study show an increased arterial stiffness and an underlying endothelial dysfunction in daily snus users as compared to matched non-tobacco controls. These findings indicate that long-term use of snus may alter the function of the endothelium and therefore reinforces the assertion that chronic snus use is correlated to an increased risk of development of cardiovascular disease.