Harmful and Potentially Harmful Constituents in E-Liquids and Aerosols from Electronic Nicotine Delivery Systems (ENDS).

In 2012, the U.S. Food & Drug Administration (FDA) published an established list of 93 harmful and potentially harmful constituents (HPHCs) targeting four tobacco product types (cigarettes, cigarette tobacco, roll-your-own tobacco, smokeless tobacco).

Environmental persistence, bioaccumulation, and hazards of chemicals in e-cigarette e-liquids: short-listing chemicals for risk assessments.

Background/methods: Increased use and sales of e-cigarettes raises concerns about the potential environmental impacts throughout their life-cycle. However, few available research studies focus on the environmental impacts and ecotoxicity of e-cigarettes. In this study, we short-list e-liquid chemicals from published literature that should be considered in future environmental impact and risk assessments.

Harmful and Potentially Harmful Constituents in the Filler and Smoke of Tobacco-Containing Tobacco Products.

The U.S. Food and Drug Administration established a list of 93 harmful and potentially harmful constituents (HPHCs) in tobacco products.

A Computational Approach for Respiratory Hazard Identification of Flavor Chemicals in Tobacco Products.

Flavor chemicals contribute to the appeal and toxicity of tobacco products, including electronic nicotine delivery systems (ENDS). The assortment of flavor chemicals available for use in tobacco products is extensive. In this study, a chemistry-driven computational approach was used to evaluate flavor chemicals based on intrinsic hazardous structures and reactivity of chemicals.

Method Validation Approaches for Analysis of Constituents in ENDS.

Objective: We assessed how many peer-reviewed publications reporting chemical quantities and/or yields from electronic nicotine delivery systems (ENDS) have included adequate method validation characteristics in the publication for appropriate interpretation of data quality for informing tobacco regulatory science.

Methods: We searched 5 databases (Web of Knowledge, PubMed, SciFinder, Embase, EBSCOhost) for ENDS publications between January 2007 and September 2018. Of the 283 publications screened, 173 publications were relevant for analysis.

Emissions of Free Radicals, Carbonyls, and Nicotine from the NIDA Standardized Research Electronic Cigarette and Comparison to Similar Commercial Devices.

E-cigarettes (e-cigs) are a diverse and continuously evolving group of products with four generations currently in the market. The National Institute on Drug Abuse (NIDA) standardized research e-cigarette (SREC) is intended to provide researchers with a consistent e-cig device with known characteristics. Thus, we conducted laboratory-based characterizations of oxidants and nicotine in aerosols produced from SREC and other closed-system, breath-activated, commercially available e-cigs (Blu and Vuse).

Effects of Charcoal on Carbonyl Delivery from Commercial, Research, and Make-Your-Own Cigarettes.

Previous literature has shown that adding charcoal to cigarette filters can have varying effects on the delivery of toxic carbonyls depending on filter design, amount of charcoal, and puffing profiles. However, these studies have relied on either comparisons between commercially available charcoal and noncharcoal filtered cigarettes or experimental modification of filters to insert a charcoal plug into existing cellulose acetate filters. Make-your-own (MYO) cigarettes can help obviate many of the potential pitfalls of previous studies; thus, we conducted studies using commercial charcoal cigarettes and MYO cigarettes to determine the effects of charcoal on carbonyl delivery.

Free Radical, Carbonyl, and Nicotine Levels Produced by Juul Electronic Cigarettes.

Introduction: Free radicals and carbonyls produced by electronic cigarettes (e-cigs) have the potential to inflict oxidative stress. Recently, Juul e-cigs have risen drastically in popularity; however, there is no data on nicotine and oxidant yields from this new e-cig design.

Methods: Aerosol generated from four different Juul flavors was analyzed for carbonyls, nicotine, and free radicals.

Little Cigars, Filtered Cigars, and their Carbonyl Delivery Relative to Cigarettes.

Introduction: Little cigars and filtered cigars are currently growing in popularity due to their low cost and wide variety of flavors while retaining an appearance similar to cigarettes. Given the health consequences associated with cigarette use, it is important to understand the potential harm associated with these similar products. This includes the potential harm associated with carbonyls (eg, acetaldehyde, acrolein, formaldehyde, etc.

Effect of Charcoal in Cigarette Filters on Free Radicals in Mainstream Smoke.

The addition of charcoal in cigarette filters may be an effective means of reducing many toxicants from tobacco smoke. Free radicals are a highly reactive class of oxidants abundant in cigarette smoke, and here we evaluated the effectiveness of charcoal to reduce free radical delivery by comparing radical yields from commercially available cigarettes with charcoal-infused filters to those without and by examining the effects of incorporating charcoal into conventional cigarette filters on radical production. Commercial cigarettes containing charcoal filters produced 40% fewer gas-phase radicals than did regular cellulose acetate filter cigarettes when smoked using the International Organization of Standardization (ISO, p = 0.

Influence of Smoking Puff Parameters and Tobacco Varieties on Free Radicals Yields in Cigarette Mainstream Smoke.

Cigarette smoke is a major exogenous source of free radicals, and the resulting oxidative stress is one of the major causes of smoking-caused diseases. Yet, many of the factors that impact free radical delivery from cigarettes remain unclear. In this study, we machine-smoked cigarettes and measured the levels of gas- and particulate-phase radicals by electron paramagnetic resonance (EPR) spectroscopy using standardized smoking regimens (International Organization of Standardization (ISO) and Canadian Intense (CI)), puffing parameters, and tobacco blends.

Differences in nicotine dependence, smoke exposure and consumer characteristics between smokers of machine-injected roll-your-own cigarettes and factory-made cigarettes.

Background: Consumption of machine-injected roll-your-own (RYO) filtered cigarettes made from pipe tobacco increased almost 7-fold from 2008 to 2011 in the United States.

Methods: We used data from the Pennsylvania Adult Smoking Study to compare the differences in sociodemographic, smoking topography, nicotine dependence, and cotinine levels between 280 smokers using factory made (FM) cigarettes and 68 smokers using RYO cigarettes.

Results: RYO smokers were older (41 vs.

Effect of flavoring chemicals on free radical formation in electronic cigarette aerosols.

Background: Flavoring chemicals, or flavorants, have been used in electronic cigarettes (e-cigarettes) since their inception; however, little is known about their toxicological effects. Free radicals present in e-cigarette aerosols have been shown to induce oxidative stress resulting in damage to proliferation, survival, and inflammation pathways in the cell. Aerosols generated from e-liquid solvents alone contain high levels of free radicals but few studies have looked at how these toxins are modulated by flavorants.

Comparison of Biomarkers of Tobacco Exposure between Premium and Discount Brand Cigarette Smokers in the NHANES 2011-2012 Special Sample.

Increased cigarette costs have inadvertently strengthened the appeal of discounted brands to price-sensitive smokers. Although smokers perceive discounted brands as having poorer quality, little is known about their delivery of toxic tobacco smoke constituents compared with premium-branded tobacco products. We investigated the differences between discount and premium brand smokers using the National Health and Nutrition Examination Survey 2011-2012 Special Smoker Sample.

Correction to Reduced nicotine content cigarettes in smokers of low socioeconomic status: study protocol for a randomized control trial.

The title of the original publication [1] had an error; furthermore there were errors in Fig. 2. The corrected version of the title and of Fig.

Effects of Solvent and Temperature on Free Radical Formation in Electronic Cigarette Aerosols.

The ever-evolving market of electronic cigarettes (e-cigarettes) presents a challenge for analyzing and characterizing the harmful products they can produce. Earlier we reported that e-cigarette aerosols can deliver high levels of reactive free radicals; however, there are few data characterizing the production of these potentially harmful oxidants. Thus, we have performed a detailed analysis of the different parameters affecting the production of free radical by e-cigarettes.

A Survey of Nicotine Yields in Small Cigar Smoke: Influence of Cigar Design and Smoking Regimens.

Introduction: Although the popularity of small cigar brands that resemble cigarettes, including both little cigars (LC) and filtered cigars (FC), has been on the rise, little is known about the delivery of nicotine from these products. Our objective was to determine the nicotine yields of small cigars in comparison to cigarettes.

Methods: Nicotine yields from LC, FC, and 3R4F and 1R6F research cigarettes were determined from mainstream smoke generated on a smoking machine under the International Organization of Standardization (ISO) and Canadian Intense (CI) methods.

Reduced nicotine content cigarettes in smokers of low socioeconomic status: study protocol for a randomized control trial.

Background: The Family Smoking Prevention and Tobacco Control Act gave the Food and Drug Administration jurisdiction over the regulation of all tobacco products, including their nicotine content. Under this act, a major strategy to reduce harm from cigarette tobacco is lowering the nicotine content without causing unintended adverse consequences. Initial research on reduced nicotine content (RNC) cigarettes has shown that smokers of these cigarettes gradually decrease their smoking frequency and biomarkers of exposure.

Effects of Topography-Related Puff Parameters on Carbonyl Delivery in Mainstream Cigarette Smoke.

Smoking topography parameters differ substantially between individual smokers and may lead to significant variation in tobacco smoke exposure and risk for tobacco-caused diseases. However, to date, little is known regarding the impact of individual puff parameters on the delivery of many harmful smoke constituents including carbonyls. To examine this, we determined the effect of altering individual puff parameters on mainstream smoke carbonyl levels in machine-smoked reference cigarettes.

Brand variation in oxidant production in mainstream cigarette smoke: Carbonyls and free radicals.

Oxidative stress/damage resulting from exposure to cigarette smoke plays a critical role in the development of tobacco-caused diseases. Carbonyls and free radicals are two major classes of oxidants in tobacco smoke. There is little information on the combined delivery of these oxidants across different cigarette brands; thus, we set out to measure and compare their levels in mainstream smoke from popular US cigarettes.

Variation in Free Radical Yields from U.S. Marketed Cigarettes.

Free radicals in tobacco smoke are thought to be an important cause of smoking-induced diseases, yet the variation in free radical exposure to smokers from different brands of commercially available cigarettes is unknown. We measured the levels of highly reactive gas-phase and stable particulate-phase radicals in mainstream cigarette smoke by electron paramagnetic resonance (EPR) spectroscopy with and without the spin-trapping agent phenyl-N-tert-butylnitrone (PBN), respectively, in 27 popular US cigarettes and the 3R4F research cigarette, machine-smoked according to the FTC protocol. We find a 12-fold variation in the levels of gas-phase radicals (1.

Effect of interior loop length on the thermal stability and pK(a) of i-motif DNA.

The four-stranded i-motif (iM) conformation of cytosine-rich DNA is important in a wide variety of biochemical systems ranging from its use in nanomaterials to a potential role in oncogene regulation. An iM is stabilized by acidic pH that allows hemiprotonated cytidines to form a C·C(+) base pair. Fundamental studies that aim to understand how the lengths of loops connecting the protonated C·C(+) pairs affect intramolecular iM physical properties are described here.

Excited state proton transfer of natural flavonoids and their chromophores in duplex and tetraplex DNAs.

Fisetin (3,7,3',4'-tetrahydroxyflavone) and quercetin (3,5,7,3',4'-pentahydroxyflavone) are the bioactive plant flavonoids that are potentially useful therapeutic drugs for the treatment of a broad spectrum of diseases, including atherosclerosis, cardiovascular disease, obesity, hypertension, and cancer. 3-Hydroxyflavone (3HF) and 7-hydroxyflavone (7HF) are the synthetic chromophores of fisetin and quercetin. We have exploited dual luminescence properties of fisetin and quercetin along with 3-HF and 7HF to examine their efficacy of binding and compare their interactions with DNA, which is one of the macromolecular targets of flavonoids in physiological systems.

Folding and hydrodynamics of a DNA i-motif from the c-MYC promoter determined by fluorescent cytidine analogs.

The four-stranded i-motif (iM) conformation of cytosine-rich DNA has importance to a wide variety of biochemical systems that range from their use in nanomaterials to potential roles in oncogene regulation. The iM structure is formed at slightly acidic pH, where hemiprotonation of cytosine results in a stable C-C(+) basepair. Here, we performed fundamental studies to examine iM formation from a C-rich strand from the promoter of the human c-MYC gene.