An Automated "Hands-Off" Method for Sampling Mainstream Smoke from Cannabis Cigarettes.

A simple-to-use, portable, and relatively inexpensive system for characterizing the chemical components of mainstream smoke from cannabis cigarettes was developed and tested by using commercial hemp cigarettes. The system is described, and its performance for reproducing actual user puff topographies is shown along with extensive chemical analysis data, including PAHs, carbonyls, and organic and elemental carbon, for a small set of initial samples. By using a solid-state flow meter and fast-response mass flow controller, the prototype can reproduce measured puff topography with excellent fidelity, which will allow users to accurately reproduce the actual inhalation patterns for various types of smoking products and consumers, and to collect samples of mainstream smoke without the need to bring test subjects or controlled substances into a laboratory.

Modeling Human Lung Cells Exposure to Wildfire Uncovers Aberrant lncRNAs Signature.

Emissions generated by wildfires are a growing threat to human health and are characterized by a unique chemical composition that is tightly dependent on geographic factors such as fuel type. Long noncoding RNAs (lncRNAs) are a class of RNA molecules proven to be critical to many biological processes, and their condition-specific expression patterns are emerging as prominent prognostic and diagnostic biomarkers for human disease. We utilized a new air-liquid interface (ALI) direct exposure system that we designed and validated in house to expose immortalized human tracheobronchial epithelial cells (AALE) to two unique wildfire smokes representative of geographic regions (Sierra Forest and Great Basin). We conducted an RNAseq analysis on the exposed cell cultures and proved through both principal component and differential expression analysis that each smoke has a unique effect on the LncRNA expression profiles of the exposed cells when compared to the control samples. Our study proves that there is a link between the geographic origin of wildfire smoke and the resulting LncRNA expression profile in exposed lung cells and also serves as a proof of concept for the in-house designed ALI exposure system. Our study serves as an introduction to the scientific community of how unique expression patterns of LncRNAs in patients with wildfire smoke-related disease can be utilized as prognostic and diagnostic tools, as the current roles of LncRNA expression profiles in wildfire smoke-related disease, other than this study, are completely uncharted.

An Automated Aerosol Collection and Extraction System to Characterize Electronic Cigarette Aerosols.

Electronic cigarette (e-cigarette) market increased by 122% during 2014-2020 and is expected to continue growing rapidly. Despite their popularity, e-cigarettes are known to emit dangerous levels of toxic compounds (e.g., carbonyls), but a lack of accurate and efficient testing methods is hindering the characterization of e-cigarette aerosols emitted by a wide variety of e-cigarette devices, e-liquids, and use patterns. The aim of this study is to fill this gap by developing an automated E-cigarette Aerosol Collection and Extraction System (E-ACES) consisting of a vaping machine and a collection/extraction system. The puffing system was designed to mimic e-cigarette use patterns (i.e., power output and puff topography) by means of a variable power-supply and a flow control system. The sampling system collects e-cigarette aerosols using a combination of glass wool and a continuously wetted denuder. After the collection stage, the system is automatically washed with absorbing and extracting liquids (e.g., methanol, an acetaldehyde-DNPH solution). The entire system is controlled by a computer. E-ACES performance was evaluated against conventional methods during measurements of nicotine and carbonyl emissions from a tank type e-cigarette. Nicotine levels measured using glass fiber filters and E-ACES were not significantly different: 201.2 ± 6.2 and 212.5 ± 17 µg/puff (p = 0.377), respectively. Differences in formaldehyde and acetaldehyde levels between filter-DNPH cartridges and the E-ACES were 14% (p = 0.057) and 13% (p = 0.380), respectively. The E-ACES showed reproducible nicotine and carbonyl testing results for the selected e-cigarette vaping conditions.

Perfluoroalkyl substances (PFAS) in surface water and sediments from two urban watersheds in Nevada, USA.

This study measured 17 perfluoroalkyl substances (PFAS) in surface water and sediments collected from six locations along the Las Vegas Wash and Lake Mead and eight locations along the Truckee River, Lake Tahoe, and Pyramid Lake in Nevada, United States. Of the 17 PFAS analyzed, 12 were detected in the surface water (n = 18) and 14 were detected in the sediments (n = 21) of the two watersheds. The total concentration of PFAS in the Truckee River water was 441.7 ng/L and the PFAS detected in the Las Vegas Wash water was 2234.3 ng/L. The predominant PFAS species found in the water were perfluorohexanoic acid (PFHxA) (1.5-187.0 ng/L), followed by perfluoropentanoic acid (PFPeA) (below detection limit [BDL] to 169.9 ng/L), perfluorooctanoic acid (PFOA) (BDL to 65.5 ng/L), and perfluorobutane sulfonic acid (PFBS) (BDL to 44.7 ng/L). The total PFAS in the sediments was 272.9 µg/kg (dry weight) for the Truckee River and 345.7 µg/kg for the Las Vegas Wash. The predominant species in the sediments were perfluorodecane sulfonic acid (PFDS) (BDL to 88.2 µg/kg), PFHxA (BDL to 20.3 µg/kg), PFBS (BDL to 29.1 µg/Kg), and perfluoroundecanoic acid (PFUA) (BDL to 22.9 µg/kg). The results demonstrated that short-chain PFAS (C ≤ 8) were more prevalent in water, whereas long-chain PFAS (C > 8) were more detectable in sediments. The Las Vegas Wash water had much higher PFAS levels compared with the Truckee River water. The PFAS concentrations and detection frequencies also significantly decreased in summer compared with winter along the Las Vegas Wash.

The Impact of Device Settings, Use Patterns, and Flavorings on Carbonyl Emissions from Electronic Cigarettes.

Health impacts of electronic cigarette (e-cigarette) vaping are associated with the harmful chemicals emitted from e-cigarettes such as carbonyls. However, the levels of various carbonyl compounds under real-world vaping conditions have been understudied. This study evaluated the levels of carbonyl compounds (e.g., formaldehyde, acetaldehyde, glyoxal, and diacetyl, etc.) under various device settings (i.e., power output), vaping topographies, and e-liquid compositions (i.e., base liquid, flavor types). The results showed that e-vapor carbonyl levels were the highest under higher power outputs. The propylene glycol (PG)-based e-liquids generated higher formaldehyde and acetaldehyde than vegetable glycerin (VG)-based e-liquids. In addition, fruit flavored e-liquids (i.e., strawberry and dragon fruit) generated higher formaldehyde emissions than mint/menthol and creamy/sweet flavored e-liquids. While single-top coils formed 3.5-fold more formaldehyde per puff than conventional cigarette smoking, bottom coils generated 10-10,000 times less formaldehyde per puff. In general, increases in puff volume and longer puff durations generated significantly higher amounts of formaldehyde. While e-cigarettes emitted much lower levels of carbonyl compounds compared to conventional cigarettes, the presence of several toxic carbonyl compounds in e-cigarette vapor may still pose potential health risks for users without smoking history, including youth. Therefore, the public health administrations need to consider the vaping conditions which generated higher carbonyls, such as higher power output with PG e-liquid, when developing e-cigarette product standards.

Indoor Air Quality and Passive E-cigarette Aerosol Exposures in Vape-Shops.

INTRODUCTION: Direct emissions of nicotine and harmful chemicals from electronic cigarettes (e-cigarettes) have been intensively studied, but secondhand and thirdhand e-cigarette aerosol (THA) exposures in indoor environments are understudied. AIMS AND METHODS: Indoor CO2, NO2, particulate matter (PM2.5), aldehydes, and airborne nicotine were measured in five vape-shops to assess secondhand exposures. Nicotine and tobacco-specific nitrosamines were measured on vape-shop surfaces and materials (glass, paper, clothing, rubber, and fur ball) placed in the vape-shops (14 days) to study thirdhand exposures. RESULTS: Airborne PM2.5, formaldehyde, acetaldehyde, and nicotine concentrations during shop opening hours were 21, 3.3, 4.0, and 3.8 times higher than the levels during shop closing hours, respectively. PM2.5 concentrations were correlated with the number of e-cigarette users present in vape-shops (ρ = 0.366-0.761, p < .001). Surface nicotine, 4-(N-methyl-N-nitrosamino)-4-(3-pyridyl)butanal (NNA), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were also detected at levels of 223.6 ± 313.2 µg/m2, 4.78 ± 11.8 ng/m2, and 44.8 ± 102.3 ng/m2, respectively. Substantial amounts of nicotine (up to 2073 µg/m2) deposited on the materials placed within the vape-shops, and NNA (up to 474.4 ng/m2) and NNK (up to 184.0 ng/m2) were also formed on these materials. The deposited nicotine concentrations were strongly correlated with the median number of active vapers present in a vape-shop per hour (ρ = 0.894-0.949, p = .04-.051). NNK levels on the material surfaces were significantly associated with surface nicotine levels (ρ=0.645, p = .037). CONCLUSIONS: Indoor vaping leads to secondhand and THA exposures. Thirdhand exposures induced by e-cigarette vaping are comparable or higher than that induced by cigarette smoking. Long-term studies in various microenvironments are needed to improve our understanding of secondhand and THA exposures. IMPLICATIONS: This study adds new convincing evidence that e-cigarette vaping can cause secondhand and THA exposures. Our findings can inform Occupational Safety and Health Administration, state authorities, and other government agencies regarding indoor air policies related to e-cigarette use, particularly in vape-shops. There is an urgent need to ensure that vape-shops maintain suitable ventilation systems and cleaning practices to protect customers, employees, and bystanders. Our study also demonstrates that nicotine can deposit or be adsorbed on baby's clothes and toys, and that tobacco-specific nitrosamines can form and retain on baby's clothes, highlighting children's exposure to environmental e-cigarette aerosol and THA at home is of a particular concern.

Harmful chemicals emitted from electronic cigarettes and potential deleterious effects in the oral cavity.

Use of electronic nicotine delivery systems (ENDS), such as electronic cigarettes (e-cigs), is increasing across the US population and is particularly troubling due to their adoption by adolescents, teens, and young adults. The industry's marketing approach for these instruments of addiction has been to promote them as a safer alternative to tobacco, a behavioral choice supporting smoking cessation, and as the 'cool' appearance of vaping with flavored products (e.g. tutti frutti, bubble gum, and buttered popcorn etc.). Thus, there is a clear need to better document the health outcomes of e-cig use in the oral cavity of the addicted chronic user. There appears to be an array of environmental toxins in the vapors, including reactive aldehydes and carbonyls resulting from the heating elements action on fluid components, as well as from the composition of chemical flavoring agents. The chemistry of these systems shows that the released vapors from the e-cigs frequently contain levels of environmental toxins that considerably exceed federal occupational exposure limits. Additionally, the toxicants in the vapors appear to be retained in the host fluids/tissues at levels often approximating 90% of the levels in the e-cig vapors. These water-soluble reactive toxins can challenge the oral cavity constituents, potentially contributing to alterations in the autochthonous microbiome and host cells critical for maintaining oral homeostasis. This review updates the existing chemistry/environmental aspects of e-cigs, as well as providing an overview of the somewhat limited data on potential oral health effects that could occur across the lifetime of daily e-cig users.

Carbonyls and Carbon Monoxide Emissions from Electronic Cigarettes Affected by Device Type and Use Patterns.

Dangerous levels of harmful chemicals in electronic cigarette (e-cigarette) aerosols were reported by several studies, but variability in e-cigarette design and use patterns, and a rapid development of new devices, such as JUUL, hamper efforts to develop standardized testing protocols and understand health risks associated with e-cigarette use. In this study, we investigated the relative importance of e-cigarette design, power output, liquid composition, puff topography on e-cigarette emissions of carbonyl compounds, carbon monoxide (CO), and nicotine. Four popular e-cigarette devices representing the most common e-cigarette types (e.g., cig-a-like, top-coil, 'mod', and 'pod') were tested. Under the tested vaping conditions, a top-coil device generated the highest amounts of formaldehyde and CO. A 'pod' type device (i.e., JUUL) emitted the highest amounts of nicotine, while generating the lowest levels of carbonyl and CO as compared to other tested e-cigarettes. Emissions increased nearly linearly with puff duration, while puff flow had a relatively small effect. Flavored e-liquids generated more carbonyls and CO than unflavored liquids. Carbonyl concentrations and CO in e-cigarette aerosols were found to be well correlated. While e-cigarettes emitted generally less CO and carbonyls than conventional cigarettes, daily carbonyl exposures from e-cigarette use could still exceed acute exposure limits, with the top-coil device potentially posing more harm than conventional cigarettes.

Investigating E-Cigarette Particle Emissions and Human Airway Depositions under Various E-Cigarette-Use Conditions.

E-cigarette use is dramatically increasing, particularly with adolescents. While the chemical composition of e-liquids and e-vapor is well characterized, the particle size distribution and the human airways deposition patterns of e-cigarette particles are understudied and poorly understood despite their likely contribution to adverse health effects from e-cigarette usage. In this study, we examined the impacts of e-cigarette device power, e-liquid composition, and vaping topography on e-cigarette particle sizes and their deposition in human airways. In addition, we observed that particle measurement conditions (dilution ratio, temperature, and humidity) significantly affect measured e-cigarette particle sizes. E-cigarette power output significantly increased particle count median diameters (CMD) from 174 ± 13 (particles generated under 6.4 W) to 236 ± 14 nm (particles generated under 31.1 W). E-cigarette particles generated from propylene glycol-based e-liquids (CMD = 145 ± 8 nm and mass median diameter [MMD] = 3.06 ± 0.17 µm) were smaller than those generated from vegetable glycerin-based e-liquids (CMD = 182 ± 9 nm and MMD = 3.37 ± 0.21 µm). Puff volume also impacted vapor particle size: CMD and MMD were 154 ± 11 nm and 3.50 ± 0.27 µm, 163 ± 6 nm and 3.35 ± 0.24 µm, and 146 ± 12 nm and 2.95 ± 0.14 µm, respectively, for 35, 90, and 170 mL puffs. Estimated e-cigarette particle mass deposition fractions in tracheobronchial and bronchoalveolar regions were 0.504-0.541 and 0.073-0.306, respectively. Interestingly, e-cigarette particles are smaller than the particles generated from cigarette smoking but have similar human airway deposition patterns.

Hydroxyl Radicals in E-Cigarette Vapor and E-Vapor Oxidative Potentials under Different Vaping Patterns.

Available studies, while limited in number, suggest that e-cigarette vaping induces oxidative stress, with one potential mechanism being the direct formation of reactive oxygen species (ROS) in e-vapor. In the present studies, we measured the formation of hydroxyl radical (•OH), the most destructive ROS, in e-vapor under a range of vaping patterns (i.e., power settings, solvent concentrations, flavorings). Study results show that increased power output and puff volume correspond with the formation of significantly higher amounts of •OH in e-vapor because of elevated coil temperature and oxygen supply. Vegetable glycerin (VG) e-liquids generated higher •OH levels than propylene glycol (PG) e-liquids, as did flavored e-liquids relative to nonflavored e-liquids. E-vapor in combination with ascorbic acid, which is an abundant biological molecule in human epithelial lining fluid, can also induce •OH formation. The dose of radical per puff associated with e-cigarette vaping was 10-1000 times lower than the reported dose generated by cigarette smoking. However, the daily average •OH dose can be comparable to that from cigarette smoking depending on vaping patterns. Overall, e-cigarette users who use VG-based flavored e-cigarettes at higher power output settings may be at increased risk for •OH exposures and related health consequences such as asthma and chronic obstructive pulmonary disease.

Aldehydes in Exhaled Breath during E-Cigarette Vaping: Pilot Study Results.

Several studies have shown the presence of aldehydes (i.e., formaldehyde, acrolein) in mainstream emissions of some e-cigarettes. For this reason, concerns have been raised regarding potential toxicity. The purpose of this research was to measure levels of carbonyls in exhaled breath of e-cigarette users during "vaping" sessions and estimate the respiratory tract (RT) uptake of specific aldehydes, including formaldehyde and acetaldehyde. We measured concentrations of 12 carbonyls in e-cigarette aerosols produced directly by e-cigarettes and in the exhaled breath of 12 participants (19 sessions). Carbonyls were sampled on 2,4-dinitrophenylhydrazine (DNPH) cartridges and analyzed with high performance liquid chromatography (HPLC) coupled with a UV/Vis photodiode detector. We found that in most cases, levels of aldehydes and methyl ethyl ketone (MEK) were significantly higher (2⁻125 times) in exhaled e-cigarette breaths than in pre-exposed breath. Exposure levels for the most abundant individual carbonyls in e-cigarette emissions-formaldehyde, acetaldehyde, acrolein-were between the limit of quantification (LOQ) and 24.4 µg·puff-1. The mean retention of formaldehyde in the respiratory tract was 99.7 ± 0.9% for all participants, while acetaldehyde retention was 91.6 ± 9.9%. Within the limitation of a small number of participants, our results showed that there is an increase in breath carbonyls during e-cigarette use.

Evaluation of E-Vapor Nicotine and Nicotyrine Concentrations under Various E-Liquid Compositions, Device Settings, and Vaping Topographies.

Nicotine is one of the major components of electronic cigarette (e-cigarette) emissions. Nicotyrine is a product of nicotine dehydrogenation in e-vapor and is a known inhibitor of human cytochrome P450 enzyme, which mediates nicotine metabolism. However, the emission of nicotine and especially nicotyrine from e-cigarettes has not been studied under real-world vaping patterns. This study examined the impact of e-liquid composition, e-cigarette device power output, and vaping topography on nicotine and nicotyrine concentrations under real-world vaping patterns. The amount of nicotine emitted from e-cigarettes vaped at high e-liquid nicotine levels, high device power, and large puff volumes ranged from 0.365 µg/puff to 236 µg/puff and was comparable to the amount of nicotine emitted from regular cigarettes. E-cigarette coil temperatures (200-300 °C) favored the formation of nicotyrine: E-cigarette vaping generated 2- to 63-fold more nicotyrine per unit nicotine emission than conventional cigarette smoking. High nicotyrine emission from e-cigarettes indicates that nicotine metabolism could be potentially interrupted, which could lead to reduced e-cigarette usage, and result in lower exposures to toxic chemicals (e.g., formaldehyde and acetaldehyde). However, higher serum nicotine levels might increase cancer risks by stimulating nicotinic acetylcholine receptors (nAchRs).

Land use regression models to assess air pollution exposure in Mexico City using finer spatial and temporal input parameters.

The Mexico City Metropolitan Area (MCMA) is one of the largest and most populated urban environments in the world and experiences high air pollution levels. To develop models that estimate pollutant concentrations at fine spatiotemporal scales and provide improved air pollution exposure assessments for health studies in Mexico City. We developed finer spatiotemporal land use regression (LUR) models for PM2.5, PM10, O3, NO2, CO and SO2 using mixed effect models with the Least Absolute Shrinkage and Selection Operator (LASSO). Hourly traffic density was included as a temporal variable besides meteorological and holiday variables. Models of hourly, daily, monthly, 6-monthly and annual averages were developed and evaluated using traditional and novel indices. The developed spatiotemporal LUR models yielded predicted concentrations with good spatial and temporal agreements with measured pollutant levels except for the hourly PM2.5, PM10 and SO2. Most of the LUR models met performance goals based on the standardized indices. LUR models with temporal scales greater than one hour were successfully developed using mixed effect models with LASSO and showed superior model performance compared to earlier LUR models, especially for time scales of a day or longer. The newly developed LUR models will be further refined with ongoing Mexico City air pollution sampling campaigns to improve personal exposure assessments.

Asthma, oculonasal symptoms, and skin test sensitivity across National Health and Nutrition Examination Surveys.

BACKGROUND: The increasing prevalence of allergies and asthma has been reported. However, the progression of the prevalence of allergy (the "allergic diathesis progression") has not been examined over time from skin test positivity to oculonasal symptoms to the development of asthma. OBJECTIVE: To investigate the change in the prevalences and associations of positive skin test reactions, oculonasal symptoms, and asthma during the Second and Third National Health and Nutrition Examination Surveys (NHANES II and NHANES III, respectively). METHODS: Data collected during NHANES II and III were used. The prevalence and associations of positive skin test reactions, oculonasal symptoms, and asthma and the linear trend of oculonasal symptoms and asthma prevalence across different cumulative positive skin test reactions were calculated for each NHANES period. RESULTS: From NHANES II to NHANES III, the prevalence of asthma doubled (2 times) and increased for positive skin test reactions (2.2 times), oculonasal symptoms (3.3 times), and concurrence of asthma, oculonasal symptoms, and positive skin test reactions (5.3 times). People were sensitive to an increasing number of allergens. Positive skin test reactions increased from 0.2% (NHANES II) to 2.7% (NHANES III) for people allergic to all 6 allergens. CONCLUSION: Despite some methodologic differences in skin tests across NHANES II and III, this study demonstrated significant increases in allergen sensitivities (prevalence and number of allergens), oculonasal symptoms, and asthma over a 20-year course, indicating that increased sensitivity led to increased allergic symptoms and asthma during the 20 years from NHANES II to NHANES III.

Has the mist been peered through? Revisiting the building blocks of human health risk assessment for electronic cigarette use.

Background: Electronic cigarettes, battery-powered nicotine delivery devices, have been increasingly used in the past decade. However, human health risks associated with E-vapor inhalation have not been fully characterized. Aims: This critical review aims at revisiting the building blocks of human health risk assessment, summarizing the state of the science, and identifying major knowledge gaps in exposure assessment and toxicity assessment. Approach: A qualitative research synthesis was conducted based on scientific findings reported to date in peer-reviewed publications and our own preliminary experimental results. Results: There are a limited number of studies across all lines of evidence on E-vapor exposure and the health impacts of E-vapor inhalation. E-cigarette may be as efficient as traditional cigarettes in nicotine delivery, especially for experienced users, and studies suggest lower emissions of air toxics from E-cigarette vapor and lower second- and third-hand vapor exposures. But some toxic emissions may surpass those of traditional cigarettes, especially under high voltage vaping conditions. Experimentally, E-vapor/E-liquid exposures reduce cell viability and promote pro-inflammatory cytokine release. User vulnerability to concomitant environmental agent exposures, such as viruses and bacteria, may potentially be increased. Conclusion: While evidence to date suggests that e-cigarettes release fewer toxins and carcinogens and compared to cigarettes, E-vapor is not safe and might adversely affect human immune functions. Major knowledge gaps hinder risk quantification and effective regulation of E-cigarette products including: 1) lack of long-term exposure studies; 2) lack of understanding of biological mechanisms associated with exposure; and 3) lack of integration of exposure and toxicity assessments.,. Better data are needed to inform human health risk assessments and to better understand the public health impact of E-vapor exposures.

A Novel High-Throughput Approach to Measure Hydroxyl Radicals Induced by Airborne Particulate Matter.

Oxidative stress is one of the key mechanisms linking ambient particulate matter (PM) exposure with various adverse health effects. The oxidative potential of PM has been used to characterize the ability of PM induced oxidative stress. Hydroxyl radical (•OH) is the most destructive radical produced by PM. However, there is currently no high-throughput approach which can rapidly measure PM-induced •OH for a large number of samples with an automated system. This study evaluated four existing molecular probes (disodium terephthalate, 3'-p-(aminophenyl)fluorescein, coumarin-3-carboxylic acid, and sodium benzoate) for their applicability to measure •OH induced by PM in a high-throughput cell-free system using fluorescence techniques, based on both our experiments and on an assessment of the physicochemical properties of the probes reported in the literature. Disodium terephthalate (TPT) was the most applicable molecular probe to measure •OH induced by PM, due to its high solubility, high stability of the corresponding fluorescent product (i.e., 2-hydroxyterephthalic acid), high yield compared with the other molecular probes, and stable fluorescence intensity in a wide range of pH environments. TPT was applied in a high-throughput format to measure PM (NIST 1648a)-induced •OH, in phosphate buffered saline. The formed fluorescent product was measured at designated time points up to 2 h. The fluorescent product of TPT had a detection limit of 17.59 nM. The soluble fraction of PM contributed approximately 76.9% of the •OH induced by total PM, and the soluble metal ions of PM contributed 57.4% of the overall •OH formation. This study provides a promising cost-effective high-throughput method to measure •OH induced by PM on a routine basis.