A review of the toxicity of ingredients in e-cigarettes, including those ingredients having the FDA's "Generally Recognized as Safe (GRAS)" regulatory status for use in food.

INTRODUCTION: Some firms and marketers of electronic cigarettes (e-cigarettes; a type of electronic nicotine delivery system (ENDS)) and refill liquids (e-liquids) have made claims about the safety of ingredients used in their products based on the term "GRAS or Generally Recognized As Safe" (GRAS). However, GRAS is a provision within the definition of a food additive under section 201(s) (21 U.S.C. 321(s)) of the U.S. Federal Food Drug and Cosmetic Act (FD&C Act). Food additives and GRAS substances are by the FD&C Act definition intended for use in food, thus safety is based on oral consumption; the term GRAS cannot serve as an indicator of the toxicity of e-cigarette ingredients when aerosolized and inhaled (i.e., vaped). There is no legal or scientific support for labeling e-cigarette product ingredients as "GRAS". This review discusses our concerns with the GRAS provision being applied to e-cigarette products and provides examples of chemical compounds that have been used as food ingredients but have been shown to lead to adverse health effects when inhaled. The review provides scientific insight into the toxicological evaluation of e-liquid ingredients and their aerosols to help determine the potential respiratory risks associated with their use in e-cigarettes. IMPLICATIONS: The rise in prevalence of e-cigarette use and emerging evidence of adverse effects, particularly on lung health, warrant assessing all aspects of e-cigarette toxicity. One development is manufacturers' stated or implied claims of the safety of using e-cigarette products containing ingredients determined to be "Generally Recognized As Safe" (GRAS) for use in food. Such claims, typically placed on e-cigarette product labels and used in marketing, are unfounded, as pointed out by the United States Food and Drug Administration (FDA)1 and the Flavor and Extract Manufacturers Association (FEMA)2. Assessment of inhalation health risks of all ingredients used in e-liquids, including those claimed to be GRAS, is warranted.

Effects of E-Cigarette Flavor Enhancing Capsules on Inhalable Aerosols.

The flavor of inhaled e-cigarette aerosols may be augmented using crushable flavor capsules added to e-cigarettes. For example, Puff Krush contains breakable flavor capsules in a sorbent material. The capsules are crushed, and then, aerosol passes through the saturated sorbent material before inhalation. Herein, we used NMR and GC-MS to identify the capsule medium chain triglyceride (MCT) solvent and flavorants in selected Puff Krush flavor capsules and then determined which molecules from the capsule transfer into aerosols. MCTs from the Puff Krush were not found in the aerosols, and ∼50% of Puff Krush flavorants transferred into the aerosol upon vaping.

Kinetics of Aldehyde Flavorant-Acetal Formation in E-Liquids with Different E-Cigarette Solvents and Common Additives Studied by 1H NMR Spectroscopy.

Flavorants, nicotine, and organic acids are common additives found in the e-liquid carrier solvent, propylene glycol (PG) and/or glycerol (GL), at various concentrations. Some of the most concentrated and prevalent flavorants in e-liquids include trans-cinnamaldehyde, vanillin, and benzaldehyde. Aldehyde flavorants have been shown to react with PG and GL to form flavorant-PG and -GL acetals that have unique toxicity properties in e-liquids before aerosolization. However, there is still much that remains unknown about the effects of different e-cigarette solvents, water, nicotine, and organic acids on the rate of acetalization in e-liquids. We used 1H NMR spectroscopy to determine the first-order initial rate constant, half-life, and % acetal formed at equilibrium for flavorant-acetal formation in simulated e-liquids. Herein, we report that acetalization generally occurs at a faster rate and produces greater yields in e-liquids with higher ratios of GL (relative to PG). trans-Cinnamaldehyde acetals formed the fastest in 100% PG-simulated e-liquids, followed by benzaldehyde and vanillin based on their half-lives and rate constants. The acetal yield was greatest for benzaldehyde in PG e-liquids, followed by trans-cinnamaldehyde and vanillin. Acetalization in PG e-liquids containing aldehyde flavorants was inhibited by water and nicotine but catalyzed by benzoic acid. Flavorant-PG acetal formation was generally delayed in the presence of nicotine, even if benzoic acid was present at 2-, 4-, or 10-fold the nicotine concentration, as compared to the PG e-liquids with 2.5 mg/mL flavorant. Thus, commercial e-liquids with aldehyde flavorants containing a higher GL ratio (relative to PG), little water, no nicotine, nicotine with excess organic acids, or organic acids without nicotine would undergo acetalization the fastest and with the highest yield. Many commercial e-liquids must therefore contain significant amounts of flavorant acetals.

Effects of Common e-Liquid Flavorants and Added Nicotine on Toxicant Formation during Vaping Analyzed by 1H NMR Spectroscopy.

A broad variety of e-liquids are used by e-cigarette consumers. Additives to the e-liquid carrier solvents, propylene glycol and glycerol, often include flavorants and nicotine at various concentrations. Flavorants in general have been reported to increase toxicant formation in e-cigarette aerosols, yet there is still much that remains unknown about the effects of flavorants, nicotine, and flavorants + nicotine on harmful and potentially harmful constituents (HPHCs) when aerosolizing e-liquids. Common flavorants benzaldehyde, vanillin, benzyl alcohol, and trans-cinnamaldehyde have been identified as some of the most concentrated flavorants in some commercial e-liquids, yet there is limited information on their effects on HPHC formation. E-liquids containing flavorants + nicotine are also common, but the specific effects of flavorants + nicotine on toxicant formation remain understudied. We used 1H NMR spectroscopy to evaluate HPHCs and herein report that benzaldehyde, vanillin, benzyl alcohol, trans-cinnamaldehyde, and mixtures of these flavorants significantly increased toxicant formation produced during e-liquid aerosolization compared to unflavored e-liquids. However, e-liquids aerosolized with flavorants + nicotine decreased the HPHCs for benzaldehyde, vanillin, benzyl alcohol, and a "flavorant mixture" but increased the HPHCs for e-liquids containing trans-cinnamaldehyde compared to e-liquids with flavorants and no nicotine. We determined how nicotine affects the production of HPHCs from e-liquids with flavorant + nicotine versus flavorant, herein referred to as the "nicotine degradation factor". Benzaldehyde, vanillin, benzyl alcohol, and a "flavorant mixture" with nicotine showed lower HPHC levels, having nicotine degradation factors <1 for acetaldehyde, acrolein, and total formaldehyde. HPHC formation was most inhibited in e-liquids containing vanillin + nicotine, with a degradation factor of ∼0.5, while trans-cinnamaldehyde gave more HPHC formation when nicotine was present, with a degradation factor of ∼2.5 under the conditions studied. Thus, the effects of flavorant molecules and nicotine are complex and warrant further studies on their impacts in other e-liquid formulations as well as with more devices and heating element types.

Emerging ENDS products and challenges in tobacco control toxicity research.

Electronic nicotine delivery systems (ENDS) continue to rapidly evolve. Current products pose unique challenges and opportunities for researchers and regulators. This commentary aims to highlight research gaps, particularly in toxicity research, and provide guidance on priority research questions for the tobacco regulatory community. Disposable flavoured ENDS have become the most popular device class among youth and may contain higher nicotine levels than JUUL devices. They also exhibit enhanced harmful and potentially harmful constituents production, contain elevated levels of synthetic coolants and pose environmental concerns. Synthetic nicotine and flavour capsules are innovations that have recently enabled the circumvention of Food and Drug Administration oversight. Coil-less ENDS offer the promise of delivering fewer toxicants due to the absence of heating coils, but initial studies show that these products exhibit similar toxicological profiles compared with JUULs. Each of these topic areas requires further research to understand and mitigate their impact on human health, especially their risks to young users.

Adverse Reactions in a Phase 1 Trial of the Anti-Malarial DM1157: An Example of Pharmacokinetic Modeling and Simulation Guiding Clinical Trial Decisions.

INTRODUCTION: There is an urgent need to develop new drugs to treat malaria due to increasing resistance to first-line therapeutics targeting the causative organism, Plasmodium falciparum (P. falciparum). One drug candidate is DM1157, a small molecule that inhibits the formation of hemozoin, which protects P. falciparum from heme toxicity. We describe a first-in-human, phase 1 trial of DM1157 in healthy adult volunteers that was halted early because of significant toxicity. METHODS: Adverse events were summarized using descriptive statistics. We used pharmacokinetic modeling to quantitatively assess whether the DM1157 exposure needed for P. falciparum inhibition was achievable at safe doses. RESULTS: We found that there was no dose where both the safety and efficacy target were simultaneously achieved; conversely, the model predicted that 27 mg was the highest dosage at which patients would consistently maintain safe exposure with multiple dosing. By pre-defining dose escalation stopping rules and conducting an interim pharmacokinetic/pharmacodynamic analysis, we determined that the study would be unable to safely achieve a dosage needed to observe an anti-malarial effect, thereby providing strong rationale to halt the study. CONCLUSION: This study provides an important example of the risks and challenges of conducting early phase research as well as the role of modeling and simulation to optimize participant safety (ClinicalTrials.gov, NCT03490162).

Meeting the Moment: Impact of TEACH Grant on US Undergraduate Education Degree Completion in High-Need Content Areas.

As part of the College Cost Reduction and Access Act (2007), the USA funded the TEACH Grant to incentivize earning a degree in a high-need content area (e.g., STEM fields, language-related areas, and Special Education) and to help meet teacher supply needs in low-income schools. Our analysis investigates the impact TEACH has had on the production of undergraduate education degrees overall and in high-need content areas. Using publicly available datasets and propensity score methods, we compare undergraduate education degree production at institutions of higher education, making comparisons between adopters and non-adopters of TEACH. Our findings suggest the adoption of TEACH had no impact on the overall production of undergraduate education degrees or production of education degrees in STEM, language-related fields, or special education. We situate our findings in the context of unrelenting demand for teachers in the USA. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1057/s41307-022-00263-3.

Ratio of Propylene Glycol to Glycerol in E-Cigarette Reservoirs Is Unchanged by Vaping As Determined by 1H NMR Spectroscopy.

E-cigarette liquids (e-liquids) contain propylene glycol (PG) and/or glycerol (GL) to deliver flavorants/nicotine. It has recently been suggested that the PG:GL ratio in e-cigarette reservoirs changes during vaping, leaving almost entirely GL after aerosolizing much of a 30:70 PG:GL mixture. To evaluate this directly, we analyzed e-liquids from e-cigarettes before and after aerosolization using 4 different coils, and aerosol samples generated using high and low e-liquid levels. The PG:GL ratios of initial and final e-liquids and aerosol samples were comparable. This is important because a large change in e-liquid composition could substantially alter the aerosol profile during a vaping session.

Determination of (R)-(+)- and (S)-(-)-Nicotine Chirality in Puff Bar E-Liquids by 1H NMR Spectroscopy, Polarimetry, and Gas Chromatography-Mass Spectrometry.

Tobacco products generally contain tobacco-derived nicotine (TDN; having ∼99+% (S)-(-)-nicotine). Recent United States regulation has led some producers to transition to synthetic ("tobacco-free") nicotine. For example, Puff Bar is now marketed with tobacco-free nicotine (TFN; presumed to be racemic). To evaluate the claim that these new products contain TFN, we evaluated the presence of the two nicotine optical isomers by 1H NMR spectroscopy, polarimetry, and gas chromatography-mass spectrometry. Older Puff Bars were found to contain (S)-(-)-nicotine, and newer "TFN" Puff Bars were found to contain both (R)-(+) and (S)-(-) isomers-indicating TFN, albeit with slightly more of the (S)-(-)-nicotine form.

Barriers, Facilitators, and Cost of Integrating HIV-Related Activities Into Sexually Transmitted Disease Partner Services in Jackson, Mississippi.

BACKGROUND: Many US health departments now integrate HIV-related outcomes (e.g., relinkage to HIV care and preexposure prophylaxis [PrEP]) into sexually transmitted disease (STD) partner services (PS) programs. We sought to determine the barriers, facilitators, and cost of integrating these activities into PS. METHODS: From 2016 to 2018, the Mississippi State Department of Health integrated 3 new activities into STD PS: HIV testing for partners of HIV-negative men who have sex with men with gonorrhea/chlamydia, relinkage to HIV care for STD PS recipients previously diagnosed with HIV, and PrEP referrals. We conducted direct observations and interviews with disease intervention specialists (DIS) in Jackson to assess barriers and facilitators to implementing these activities. We completed time and motion studies with 8 DIS and case tracking forms for 90 unique cases to estimate the incremental staff time and associated personnel cost of added services compared with a standard PS case. RESULTS: Disease intervention specialists were optimistic about integrating HIV-related activities but noted disparate data systems, nonsystematic documentation, and lack of training as barriers. The mean time for a standard STD PS case without HIV-related activities was 195 minutes (cost, $77.69/case). The cost to conduct PS for HIV-negative men who have sex with men with gonorrhea/chlamydia was 36% higher than a standard case. Integrating relinkage to care and PrEP referrals resulted in a 44% and 20% increase in cost, respectively. CONCLUSIONS: Integrating HIV care relinkage and PrEP referrals into STD partner services was generally acceptable by DIS and added marginal cost per case. Coupling these cost metrics with an assessment of the effectiveness of these activities can inform prioritization of partner services activities.

Preservice Observation in Special Education: A Validation Study.

Advancing teacher candidates' overall competence through use of valid teacher observation systems should be an essential element of teacher preparation. Yet, the field of special education has not provided observation protocols designed specifically for preservice teachers that are founded in theoretical perspectives and research on effective instruction for students with learning and other high-incidence disabilities (SWDs). To address this need, a group of researchers in special education teacher preparation and measurement developed the Preservice Observation Instrument for Special Education (POISE). The POISE is an observation system rooted in effective special education practices that support the growth of preservice teachers who will serve SWD across instructional settings. The purpose of this article is to report on the development and psychometric properties of the POISE. Specifically, we employed Kane's argument-based validity approach to frame each stage in the development process of the POISE. We conducted two phases of content validation activities, development activities, and a pilot study to assess the degree to which scores from POISE provided evidence for the scoring, generalizability, and extrapolation inferences. In the end, the POISE represents a promising observation instrument for the development of special education teacher candidates.

Unsymmetrical Bisquinolines with High Potency against P. falciparum Malaria.

Quinoline-based scaffolds have been the mainstay of antimalarial drugs, including many artemisinin combination therapies (ACTs), over the history of modern drug development. Although much progress has been made in the search for novel antimalarial scaffolds, it may be that quinolines will remain useful, especially if very potent compounds from this class are discovered. We report here the results of a structure-activity relationship (SAR) study assessing potential unsymmetrical bisquinoline antiplasmodial drug candidates using in vitro activity against intact parasites in cell culture. Many unsymmetrical bisquinolines were found to be highly potent against both chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum parasites. Further work to develop such compounds could focus on minimizing toxicities in order to find suitable candidates for clinical evaluation.

Free-Base Nicotine Fraction αfb in Non-Aqueous versus Aqueous Solutions: Electronic Cigarette Fluids Without versus With Dilution with Water.

An important design aspect of electronic cigarettes ("e-cigarettes") is the nature of the acid/base chemistry in the e-liquid phase. E-liquids having formulations similar to those of early products are mixes of propylene glycol/glycerol (PG/GL) plus free-base (fb) nicotine and (usually) flavor chemicals that are either rather weak or non-acid/base actors in PG/GL. The fraction of nicotine in the fb form is denoted (αfb)e-liquid, with a possible range of 0 < (αfb)e-liquid < 1. For e-liquids of an early design, (αfb)e-liquid ≈ 1. Because e-cigarette aerosols high in fb nicotine are harsh upon inhalation, many commercial e-liquids now also contain variable levels of an acid additive (e.g., benzoic acid, levulinic acid, etc.) to protonate the nicotine and form dissolved "nicotine salts": (αfb)e-liquid values significantly less than 1 are now common. A framework is developed for predicting αfb values in a given medium based on the following: (1) acid/nicotine ratios and (2) overall acid + nicotine protonation constant (Koa) values. This framework is required for understanding (1) e-liquid design in regard to how acid additives affect (αfb)e-liquid values, and (2) why (αfb)e-liquid values cannot, in general, be measured by any method that involves significant dilution with water.

Nicotine in tobacco product aerosols: 'It's déjà vu all over again'.

INTRODUCTION: The distribution of nicotine among its free-base (fb) and protonated forms in aerosolised nicotine affects inhalability. It has been manipulated in tobacco smoke and now in electronic cigarettes by the use of acids to de-freebase nicotine and form 'nicotine salts'. METHODS: Measurements on electronic cigarette fluids (e-liquids) were carried out to determine (1) the fraction of nicotine in the free-base form (αfb) and (2) the levels of organic acid(s) and nicotine. Samples included JUUL 'pods', 'look-a-like/knock-off' pods and some bottled 'nicotine salt' and 'non-salt' e-liquids. RESULTS: αfb= 0.12 ±0.01 at 40°C (≈ 37°C) for 10 JUUL products, which contain benzoic acid; nicotine protonation is extensive but incomplete. DISCUSSION: First-generation e-liquids have αfb ≈ 1. At cigarette-like total nicotine concentration (Nictot) values of ~60 mg/mL, e-liquid aerosol droplets with αfb≈ 1 are harsh upon inhalation. The design evolution for e-liquids has paralleled that for smoked tobacco, giving a 'déjà vu' trajectory for αfb. For 17th-century 'air-cured' tobacco, αfb in the smoke particles was likely ≥ 0.5. The product αfbNictot in the smoke particles was high. 'Flue-curing' retains higher levels of leaf sugars, which are precursors for organic acids in tobacco smoke, resulting in αfb ≈ 0.02 and lowered harshness. Some tobacco cigarette formulations/designs have been adjusted to restore some nicotine sensory 'kick/impact' with αfb≈ 0.1, as for Marlboro. Overall, for tobacco smoke, the de-freebasing trajectory was αfb ≥ 0.5 → ~0 →~0.1, as compared with αfb= ~1 →~0.1 for e-cigarettes. For JUUL, the result has been, perhaps, an optimised, flavoured nicotine delivery system. The design evolution for e-cigarettes has made them more effective as substitutes to get smokers off combustibles. However, this evolution has likely made e-cigarette products vastly more addictive for never-smokers.

Sucralose-Enhanced Degradation of Electronic Cigarette Liquids during Vaping.

Electronic cigarette liquids (e-liquids) with sweetener additives such as sucralose, a synthetic chlorinated disaccharide, are popular among some e-cigarette consumers; sucralose can be added either by the manufacturer or by the consumer. The prevalence of sucralose in commercial e-liquids is not known, nor is the typical concentration of sucralose when present; labels are not required to disclose ingredient information. Here, we report the effects of sucralose on e-liquid degradation upon e-cigarette vaping as studied using 1H NMR spectroscopy, ion chromatography, and gas chromatography coupled with detection by mass spectrometry or flame ionization detector. Sucralose was found to be subject to degradation when included in propylene glycol + glycerol based e-liquids and vaped; the presence of sucralose in the e-liquids also resulted in altered and enhanced solvent degradation. In particular, production of aldehydes (carbonyls) and hemiacetals (which have implications for health) was enhanced, as demonstrated by 1H NMR. The presence of sucralose at 0.03 mol % (0.14 wt %) in an e-liquid also resulted in production of potentially harmful organochlorine compounds and catalyzed the cyclization of aldehydes with solvents to acetals upon vaping; the presence of chloride in e-liquid aerosols was confirmed by ion chromatography. Quantities of sucralose as low as 0.05 mol % (0.24 wt %) in e-liquids lead to significant production of solvent degradation products.

Free-Base Nicotine Is Nearly Absent in Aerosol from IQOS Heat-Not-Burn Devices, As Determined by 1H NMR Spectroscopy.

Heat-not-burn products, eg, I quit ordinary smoking (IQOS), are becoming popular alternative tobacco products. The nicotine aerosol protonation state has addiction implications due to differences in absorption kinetics and harshness. Nicotine free-base fraction (αfb) ranges from 0 to 1. Herein, we report αfb for IQOS aerosols by exchange-averaged 1H NMR chemical shifts of the nicotine methyl protons in bulk aerosol and verified by headspace-solid phase microextraction-gas chromatography-mass spectrometry. The αfb ≈ 0 for products tested; likely a result of proton transfer from acetic acid and/or other additives in the largely aqueous aerosol. Others reported higher αfb for these products, however, their methods were subject to error due to solvent perturbation.

Integrating Human Immunodeficiency Virus Testing Into Syphilis Partner Services in Mississippi to Improve Human Immunodeficiency Virus Case Finding.

BACKGROUND: Mississippi has the 10th highest rate of new human immunodeficiency virus (HIV) infections in the United States. The Mississippi State Department of Health (MSDH) integrated partner HIV testing into syphilis partner services (PS) in 2014, but the effectiveness of this as an HIV case finding strategy has not been evaluated. METHODS: We identified all early syphilis (primary, secondary, and early latent) case records reported from July 1, 2014, to December 31, 2016, excluding case records for people concurrently newly diagnosed with HIV. Among sex partners of these people, we identified new diagnoses of early syphilis and HIV. We calculated the number needed to interview as the number of syphilis index case patients interviewed divided by the number of partners newly diagnosed with early syphilis or HIV. RESULTS: A total of 1535 (95%) of the 1619 early syphilis index case patients were interviewed for PS. These case patients named 2267 partners, of whom 1868 (82%) were contacted by MSDH. Among partners, 1508 (81%) tested for syphilis and 745 (56%) of 1321 partners not previously diagnosed with HIV were tested for HIV. Partner services identified 696 new early syphilis case patients (46%) and 24 (3.2%) new HIV case patients among partners. Sixty-four index case patient interviews were needed to identify 1 new case of HIV, and 2 interviews were needed to identify 1 new case of syphilis among partners. CONCLUSIONS: Syphilis PS allowed MSDH to interact with 1592 men who have sex with men over a 30-month period and was effective for identifying people newly infected with early syphilis and HIV. Increasing HIV testing among partners of syphilis case patients could increase HIV case finding in Mississippi.

Triacetin Enhances Levels of Acrolein, Formaldehyde Hemiacetals, and Acetaldehyde in Electronic Cigarette Aerosols.

The health effects of inhaled electronic cigarette (e-cigarette) flavoring compounds are largely unknown. Earlier reports of their chemical reactivity have been conflicting, with some claiming, for example, that the degradation of flavoring chemicals in e-cigarettes to aldehydes is statistically insignificant. It is thus important to understand how these molecules react to afford enhanced aerosol products. The purpose of the current study was to investigate the origin of formaldehyde, acrolein, and acetaldehyde in e-cigarettes that contain the popular additive, triacetin (TA). By using 13C labeling and a combination of 1H NMR and 13C NMR, we were able to identify that ester hydrolysis of TA occurs to form acetic acid (HOAc) during aerosolization. The released HOAc acts as a catalyst in the degradation of propylene glycol (PG) and glycerol (GLY), increasing the formation of formaldehyde hemiacetals, acrolein, and acetaldehyde. A solution of 10% TA in 1:1 PG/GLY e-liquid was aerosolized using two different e-cigarettes at two wattages. Each device exhibited a significant increase in aldehyde levels, of up to 185% compared to the aerosol from a 1:1 PG/GLY e-liquid. In addition, the GLY formaldehyde hemiacetal was more predominant within the presence of HOAc, indicating that GLY may be relatively more prone to degradation from protonation.

Free-Base Nicotine Determination in Electronic Cigarette Liquids by 1H NMR Spectroscopy.

E-liquids usually contain significant nicotine, which will exist primarily in two forms, monoprotonated and free-base, the proportions of which are alterable through the effective pH of the medium. The fraction of nicotine in the free-base form is αfb, with 0 ≤ αfb ≤ 1. When dosed via aerosol, the two nicotine forms have different mechanisms and kinetics of delivery, as well as differing implications for harshness of the inhaled aerosol, so αfb is relevant regarding abuse liability. Previous attempts to determine αfb in electronic cigarette liquids and vapor have been flawed. We employed the exchange-averaged 1H NMR chemical shifts of nicotine to determine αfb in samples of e-liquids. This method is rapid and direct and can also be used with collected aerosol material. The e-liquids tested were found to have 0.03 ≤ αfb ≤ 0.84. The αfb values in collected aerosol liquid samples were highly correlated with those for the parent e-liquids. E-liquids designed to combine high total nicotine level (addictive delivery) with low αfb (for ease of inhalation) are likely to be particularly problematic for public health.