Phytol, not propylene glycol, causes severe pulmonary injury after inhalation dosing in Sprague-Dawley rats

Biological Response after 14-Day Cannabidiol and Propylene Glycol Inhalation in Sprague-Dawley Rats

Objective: Cannabidiol (CBD), a phytocannabinoid of increasing interest for its purported therapeutic effects, is primarily consumed via ingestion and inhalation. While the toxicology of orally administered CBD has been reported, little is known about the effects of CBD inhalation. Doses selected for the present analysis allowed for evaluation of dose-response at concentrations >100-fold higher than typical human consumption levels. Materials and Methods: CBD (98.89% pure) was formulated in propylene glycol (PG) and aerosolized by nebulization to evaluate biological response after nose-only inhalation. Sprague Dawley rats (n = 35 males, 30 females) were exposed to 1.0 and 1.3 mg/L nominal concentrations of CBD and PG, respectively, for 12-180 min. Resulting average daily presented dose ranges were 8.9-138.5 mg/kg CBD and 11.3-176.0 mg/kg PG. Aerosols of 1.4 µm median diameter were achieved. Biological response indicators included clinical signs, clinical chemistry, hematology, body/organ weights, and pulmonary/systemic histopathology. Results: Inflammatory and necrotic responses were observed in the nose at the highest doses of CBD. Limited findings in the larynx and lung were mainly observed at higher doses. There were no histological findings in extrapulmonary organs. Dosimetry modeling differentiated the no observable adverse effect level between the nasal region and lungs to be 2.8 and 10.6 mg/kg CBD, respectively. Conclusions: Dose-depending findings of histological changes in the respiratory tract are observed at high doses. At lower doses consistent with typical over-the-counter vape products there appears to be substantial safety margin in the present study (93- and 353-fold lower for nose and lung, respectively).

Use of flavored cannabis vaping products in the US, Canada, Australia, and New Zealand: findings from the international cannabis policy study wave 4 (2021)

Background: Vaping is an increasingly popular mode of cannabis use. Few studies have characterized the role of flavors in cannabis e-liquids.Objectives: To explore the prevalence of flavored vaping liquids, including differences between countries and correlates of use.Methods: Data were from Wave 4 (2021) of the International Cannabis Policy Study with national samples aged 16-65 in Canada, the United States (US), Australia, and New Zealand. The sample comprised 52,938 respondents, including 6,265 who vaped cannabis e-liquids in the past 12-months (2,858 females, 3,407 males). Logistic regression models examined differences in the use of flavored e-liquids between countries and sociodemographic characteristics.Results: The prevalence of vaping cannabis e-liquids was highest in the US (15.3%) and Canada (10.7%) compared to Australia (4.0%) and New Zealand (3.7%). Among past 12-month cannabis consumers, 57.5% reported using flavored vaping liquids, 34.2% used unflavored vaping products and 8.3% did not know. People who vape in Australia were most likely to report using flavored liquids compared to New Zealand (OR = 2.29), Canada (OR = 3.14), and the US (OR = 3.14) (p < .05 for all). Fruit was the most reported vaping flavor (40.8%), followed by candy/dessert (20.4%) and vanilla (15.2%). Use of flavored vapes was greater among younger, ethnic minorities, female, higher education and income adequacy, and more frequent consumers (p < .05).Conclusion: Many cannabis consumers reported using flavored e-liquids, with highest levels among young people aged 16-35. Given the high prevalence of vaping in legal markets, regulators should consider the role of flavored vaping products in promoting cannabis use among this group.

Multi-omic assessment shows dysregulation of pulmonary and systemic immunity to e-cigarette exposure

Electronic cigarette (Ecig) use has become more common, gaining increasing acceptance as a safer alternative to tobacco smoking. However, the 2019 outbreak of Ecig and Vaping-Associated Lung Injury (EVALI) alerted the community to the potential for incorporation of deleterious ingredients such as vitamin E acetate into products without adequate safety testing. Understanding Ecig induced molecular changes in the lung and systemically can provide a path to safety assessment and protect consumers from unsafe formulations. While vitamin E acetate has been largely removed from commercial and illicit products, many Ecig products contain additives that remain largely uncharacterized. In this study, we determined the lung-specific effects as well as systemic immune effects in response to exposure to a common Ecig base, propylene glycol and vegetable glycerin (PGVG), with and without a 1% addition of phytol, a diterpene alcohol that has been found in commercial products. We exposed animals to PGVG with and without phytol and assessed metabolite, lipid, and transcriptional markers in the lung. We found both lung-specific as well as systemic effects in immune parameters, metabolites, and lipids. Phytol drove modest changes in lung function and increased splenic CD4 T cell populations. We also conducted multi-omic data integration to better understand early complex pulmonary responses, highlighting a central enhancement of acetylcholine responses and downregulation of palmitic acid connected with conventional flow cytometric assessments of lung, systemic inflammation, and pulmonary function. Our results demonstrate that Ecig exposure not only leads to changes in pulmonary function but also affects systemic immune and metabolic parameters.

An in vitro evaluation of e-vapor products: The contributions of chemical adulteration, concentration, and device power

Homemade e-liquids and power-adjustable vaping devices may carry higher risks than commercial formulations and fixed-power devices. This study used human macrophage-like and bronchial epithelial (NHBE) cell cultures to investigate toxicity of homemade e-liquids containing propylene glycol and vegetable glycerin (PG/VG), nicotine, vitamin E acetate (VEA), medium-chain fatty acids (MCFAs), phytol, and cannabidiol (CBD). SmallAir™ organotypic epithelial cultures were exposed to aerosols generated at different power settings (10-50 W). Carbonyl levels were measured, and endpoints reflecting epithelial function (ciliary beating frequency [CBF]), integrity (transepithelial electrical resistance [TEER]), and structure (histology) were investigated. Treatment with nicotine or VEA alone or with PG/VG did not impact cell viability. CBD, phytol, and lauric acid caused cytotoxicity in both culture systems and increased lipid-laden macrophages. Exposure of SmallAir™ organotypic cultures to CBD-containing aerosols resulted in tissue injury and loss of CBF and TEER, while PG/VG alone or with nicotine or VEA did not. Aerosols generated with higher power settings had higher carbonyl concentrations. In conclusion, the presence and concentration of certain chemicals and device power may induce cytotoxicity in vitro. These results raise concerns that power-adjustable devices may generate toxic compounds and suggest that toxicity assessments should be conducted for both e-liquid formulations and their aerosols.

High-CBD Cannabis Vapor Attenuates Opioid Reward and Partially Modulates Nociception in Female Rats

Chronic pain patients report analgesic effects when using cannabidiol (CBD), a phytocannabinoid found in whole-plant cannabis extract (WPE). Several studies suggest that cannabis-derived products may serve as an analgesic adjunct or alternative to opioids, and importantly, CBD may also attenuate the abuse potential of opioids. Vaping is a popular route of administration among people who use cannabis, however both the therapeutic and hazardous effects of vaping are poorly characterized. Despite the fact that chronic pain is more prevalent in women, the ability of inhaled high-CBD WPE to relieve pain and reduce opioid reward has not been studied in females. Here, we present a comprehensive analysis of high-CBD WPE vapor inhalation in female rats. We found that WPE was modestly efficacious in reversing neuropathy-induced cold allodynia in rats with spared nerve injury (SNI). Chronic exposure to WPE did not affect lung cytoarchitecture or estrous cycle, and it did not induce cognitive impairment, social withdrawal or anxiolytic effects. WPE inhalation prevented morphine-induced conditioned place preference and reinstatement. Similarly, WPE exposure reduced fentanyl self-administration in rats with and without neuropathic pain. We also found that WPE vapor lacks of reinforcing effects compared to the standard excipient used in most vapor administration research. Combined, these results suggest that although high-CBD vapor has modest analgesic effects, it has a robust safety profile, no abuse potential, and it significantly reduces opioid reward in females. Clinical studies examining high-CBD WPE as an adjunct treatment during opioid use disorder are highly warranted.

Temperature dependence of emission product distribution from vaping of vitamin E acetate

Nearly two years after vitamin E acetate (VEA) was identified as the potential cause of the 2019–2020 outbreak of e-cigarette, or vaping product-associated lung injuries (EVALI), the toxicity mechanisms of VEA vaping are still yet to be fully understood. Studies since the outbreak have found that e-liquids such as VEA undergo thermal degradation during the vaping process to produce various degradation products, which may pose a greater risk of toxicity than exposure to unvaped VEA. Additionally, a wide range of customizable parameters–including the model of e-cigarette used, puffing topography, or the applied power/temperature used to generate aerosols–have been found to influence the physical properties and chemical compositions of vaping emissions. However, the impact of heating coil temperature on the chemical composition of VEA vaping emissions has not been fully assessed. In this study, we investigated the emission product distribution of VEA vaping emissions produced at temperatures ranging from 176 to 356°C, corresponding to a variable voltage vape pen set at 3.3 to 4.8V. VEA degradation was found to be greatly enhanced with increasing temperature, resulting in a shift towards the production of lower molecular weight compounds, such as the redox active duroquinone (DQ) and short-chain alkenes. Low temperature vaping of VEA resulted in the production of long-chain molecules, such as phytol, exposure to which has been suggested to induce lung damage in previous studies. Furthermore, differential product distribution was observed in VEA degradation products generated from vaping and from pyrolysis using a tube furnace in the absence of the heating coil at equivalent temperatures, suggesting the presence of external factors such as metals or oxidation that may enhance VEA degradation during vaping. Overall, our findings indicate that vaping behavior may significantly impact the risk of exposure to toxic vaping products and potential for vaping-related health concerns.

Investigation of Vaping Fluids Recovered From New York State E-Cigarette or Vaping Product Use-Associated Lung Injury Patients

E-cigarette or vaping product use-associated lung injury (EVALI) is a serious pulmonary condition that is associated with the extended use of certain vaping products. EVALI was first characterized in the summer of 2019 and has since been reported in all 50 U.S. states. From August 2019 through June 2021, the New York State Department of Health has reported more than 197 confirmed cases emanating from all regions of the state. The Wadsworth Center at the New York State Department of Heath received vaping cartridges recovered from EVALI patients for chemical analysis of their contents. Untargeted analytical methods using gas chromatography-mass spectrometry and liquid chromatography-high-resolution mass spectrometry as well as targeted analyses for a variety of analytes including cannabinoids, pesticides, vitamin E acetate (VEA) and mycotoxins were used to characterize the composition of the vaping fluids and several commercial vaping fluid additives. From the analyses of the 284 e-cigarette devices recovered from patients, 82 were found to be nicotine-containing pods, and 202 devices containing cannabis oil, apparently from unauthorized or black-market dealers. The fluids from the cannabis-oil cartridges tended to have lower levels of THCs (Δ⁹-tetrahydrocannabinol + Δ⁸-tetrahydrocannabinol) and total cannabinoids compared with those of commercially produced formulations and contained significant levels of diluents including VEA, medium-chain triglycerides, polyethylene glycol, and castor oil. VEA was the diluent most frequently detected, which was present in 132 (65.3%) of the vaping fluids that contained cannabis oil. When present, VEA ranged from 2.0 to 67.8% of the total mass of the oil with a mean content of 37.0%. In some cases, two or three diluents were detected in the same sample. The ratio of VEA to THCs varied widely, from 0.07 to 5.34. VEA and specifically the high ratios of VEA to THCs in black-market vaping fluids may be causative in EVALI. The safety of additional components and additives that are present in vaping fluids are likewise of concern.

Cannabis Vaping: Existing and Emerging Modalities, Chemistry, and Pulmonary Toxicology

The outbreak of e-cigarette or vaping product use-associated lung injury (EVALI) has been cause for concern to the medical community, particularly given that this novel illness has coincided with the COVID-19 pandemic, another cause of severe pulmonary illness. Though cannabis e-cigarettes tainted with vitamin E acetate were primarily associated with EVALI, acute lung injuries stemming from cannabis inhalation were reported in the literature prior to 2019, and it has been suggested that cannabis components or additives other than vitamin E acetate may be responsible. Despite these concerning issues, novel cannabis vaporizer ingredients continue to arise, such as Δ8-tetrahydrocannabinol, Δ10-tetrahydrocannabinol, hexahydrocannabinol, and cannabichromene. In order to address cannabis e-cigarette safety and vaping in an effective manner, we provide a comprehensive knowledge of the latest products, delivery modes, and ingredients. This perspective highlights the types of cannabis vaping modalities common to the United States cannabis market, with special attention to cartridge-type cannabis e-cigarette toxicology and their involvement in the EVALI outbreak, in particular, acute lung injurious responses. Novel ingredient chemistry, origins, and legal statuses are reviewed, as well as the toxicology of known cannabis e-cigarette aerosol components.

The influence of terpenes on the release of volatile organic compounds and active ingredients to cannabis vaping aerosols

Cannabinoid and VOC emissions from vaping cannabis concentrates vary depending on terpene content, power level and consumption method.