Since the diacetyl/3-oxobutanal pair is slightly enhanced with VEA, this is in agreement with the fact that they are from different origins and both isomers are formed when VEA and THC are vaped together. In some cases, the mixture produced more carbonyl emissions compared to the pure compounds . Although this trend is less clear within error, it may suggest some synergetic effects between THC and VEA. Moreover, the THC oil tend to produce higher acetaldehyde than VEA, which is also understandable, since the proposed thermal degradation pathway of VEA cannot explain the formation of acetaldehyde but there are reasonable pathways from cannabinoids such as CBG . More research is needed for further understanding of the thermal degradation chemistry of VEA and THC.In this dissertation, a series of studies were conducted to examine the aerosolization and thermal degradation chemistry of electronic cigarettes with the e-liquid with the composition of PG/VG/nicotine and VEA/THC oil. The most important method developed in this dissertation unambiguously identified and quantified carbonyl compounds, acids, trimming cannabis and potentially cannabinoids in e-cigarettes aerosol using HPLC-HRMS. The method includes a theoretical chemistry model that is developed for the prediction of sensitivities of deprotonation-based electrospray ionization for carbonyls and acids for which analytical standards are unavailable commercially.
The initial investigation identified and quantified 19 carbonyl compounds and acids from the vaping aerosol of the 1st generation e-cigarettes, which includes thermal degradation products from PG and VG, as well as flavoring chemicals and acid additives. Hydroxycarbonyls such as hydroxyacetone, lactaldehyde, and dihydroxyacetone, not quantified in the majority of previous e-cigarette research, were found to be significant thermal degradation products in the e-cigarette aerosol. To date, the inhalation toxicology of these hydroxycarbonyls is still unknown, which emphasizes the need for more research on the toxicology of complex products formed in vaping. The characterization of flavoring chemicals in this work shows the potential application of the HRMS method to other flavored e-cigarettes, as a large variety of flavoring chemical are carbonyls and the specific flavoring additives are proprietary. In addition to carbonyls and acids, the composition of e-cigarette aerosol as well as the relationship between the e-cigarette emissions and vaping parameters are also important for the systematic evaluation of health risks associated with e-cigarette use. A GC-MS method was developed for the quantification of PG, VG and nicotine in the particle phase of e-cigarette aerosol, while the gas phase composition was quantified by CIMS. An exponential relationship was found between the generated particle mass and measured coil temperatures, which is different than the temperatures set by the vaping device.
The mass loss of e-liquid was found mainly distributed in the gas phase, and the PG fraction in the gas phase is significantly higher than the particle phase which may due to the their volatility difference. The PG:VG fraction in the particle phase is close to that from the original e-liquid. Moreover, a general exponential trend was also found between the generated carbonyl mass and the measured temperatures, while some carbonyls were shown to have a steeper exponential relationship than others . Accordingly, two possible mechanism were proposed for the thermal degradation of PG and VG including a thermal dehydration pathway and radical reaction pathway. The thermal dehydration pathway was shown to be the main mechanism within the temperature range used for e-cigarettes. Some carbonyl compounds are mainly or entirely generated from VG, while others are mainly or entirely generated from PG. E-cigarette emissions have a linear-like relationship with the puff duration within the range of 2 – 4 s. In addition, the e-liquid of THC oil with VEA added as diluent was also tested for aerosolization and thermal degradation chemistry under different vaping parameters. It was shown adding VEA suppressed the generation of particle mass at a higher efficiency than its volume fraction would indicate, suggesting that the THC and VEA mixture forms a non-ideal solution with significant intermolecular interactions. Moreover, VEA and the ingredients in THC oil can also degrade into different thermal degradation products including carbonyls, acids and oxidative cannabinoids. A radical reaction mechanism was proposed for the thermal degradation of VEA and THC.
The stability of the alkyl radicals formed in the initial step of OHinitiated reaction is critical to the generation of final products. Multiple carbonyls were quantified and normalized by the generated particle mass in different e-liquid ratios of THC oil and VEA. The results show that some carbonyls were mainly generated by thermal degradation of VEA, which also emphasize the need of further research to better understand the chemistry of cannabis vaping with different diluents as the cannabis vaping market size has been growing rapidly. In conclusion, this dissertation utilized a systematic approach to research on the aerosolization and thermal degradation chemistry of different e-cigarettes and e-liquids. The findings suggest that, although e-cigarettes have been regarded as safe alternatives for traditional smoking worldwide, the health risk of e-cigarettes use should to be evaluated in further detail and more toxicology investigations are needed to enable exposure risk estimation of exposure to specific compounds as well as complex mixtures that can be formed during the vaping process.Marked increases in cannabis sales were reported by industry and business sources during the COVID-19 pandemic,1 and studies of cannabis users in the U.S.,2 the Netherlands,3,4 and Canada5 reported increased cannabis use during the pandemic. Content analyses of Twitter6 and other social media and online sources7 during the pandemic found increased discussion of cannabis as treatment for COVID-19. The number of cannabis dispensaries is increasing with legalization and dispensaries are an important source of marketing messages, but it is unknown to what extent online cannabis dispensary marketing activities may have contributed to increased pandemic sales. We analyzed cannabis dispensary websites to gain insight into cannabis marketing practices at the start of the COVID-19 pandemic, leveraging an existing study of a small geographic area with two different historical policy contexts. The region from the San Francisco/Bay Area extending east to the Reno area of Nevada is readily accessible by car, but includes two states with contrasting regulatory contexts: California has a long history of acceptance of cannabis including the counterculture of the 1960-1970s, medical marijuana legalization in 1996, and a longstanding cannabis cultivation. In contrast, Nevada’s medical marijuana policy was implemented fairly recently in 2015. Both states approved adult use cannabis in 2016, and deemed cannabis dispensaries essential during the pandemic. Dispensaries remained open in California; in Nevada, dispensaries were initially limited to delivery, gardening rack but in May 2020 allowed curbside pick-up and in-store purchases. An August 2020 cannabis industry report found that sales rose overall during the COVID-19 pandemic, and stated that “e-commerce solutions were the key to success”. As part of an ongoing surveillance study comparing dispensary websites in San Francisco, Alameda and Washoe Counties, we noted special COVID-19 announcements appeared days to weeks following lockdown and analyzed these to gain insight into industry marketing responses to the pandemic.We conducted a content analysis of website announcements, comparing dispensaries in San Francisco/Alameda Counties and those within a 30 mile radius of Reno, Nevada, between April-May 2020. We obtained lists of all licensed dispensaries from local health departments and verified the businesses were open using online resources . We included all dispensaries with functional websites . Three trained researchers reviewed all websites and recorded all content related to COVID-19 with screenshots. COVID-19 announcements appeared on websites shortly after the stay-at-home orders were announced, often as pop-up windows appearing on top of the home page, or as an extra web page.
We coded only content from the dispensary, not unrelated pop-up ads. The content codebook was adapted from a prior website content analysis instrument, and the team iteratively reviewed, discussed, and revised codes, including six new codes specific to the COVID-19 pandemic . Two authors double coded all COVID-19 announcements for the presence of each theme; the unit of analysis was the website. The team met weekly to review and discuss discrepancies in coding and to resolve conflicts, using a fourth investigator to adjudicate if needed. Interrater reliability measured by Krippendorff’s alpha was 0.77 – 1.0 for COVID-19 variables.COVID-19 announcements were present on 25/32 of dispensary websites in San Francisco/Alameda counties and on 9/15 of websites in the Reno area. Of the websites with COVID-19 content, almost all announced operational changes . 72% of San Francisco/Alameda and 56% of Reno websites announced safety measures like wearing masks, hand washing, cleaning surfaces, temperature checks, physical distancing, no touch payment or eliminating smell samples. Some asked patrons not to come to the dispensary if feeling ill, with reference to sick or immuno compromised clients. The majority of websites made references to, or provided links to, government or public health resources, either as the explanation for changes in operations, or to demonstrate that the dispensary was cooperating with health authorities. The look and feel of COVID-19 website announcements varied widely; most dispensaries utilized simple “pop up” windows on the site home page with text announcements to customers of altered hours, access or pick up policies. However a few created custom graphics for promotions or discounts, and one dispensary adorned their logo with a mask. Health-related announcements were present in several forms. Of San Francisco/Alameda County dispensary websites, 36% referred to their status as an essential service, a theme not found on Reno area websites. The status as an essential service was often accompanied by references to cannabis as a medicine, or a connection to health authorities. For example, one San Francisco dispensary posted a quote “Cannabis is an essential medicine for many San Francisco residents. Dispensaries can continue to operate as essential businesses during this time, while practicing social distancing and other public health recommendations” that was attributed to the San Francisco Department of Health. Another announcement stated, “So, what are the essentials? Groceries, prescription drugs, gas, urgent medical care, and weed. This list is what’s necessary for the health and safety of us all during this time.” More frequently, COVID-19 announcements included more general health statements such as, “The health and safety of our staff and customers is of the utmost importance to us.” A few dispensaries gave advice about ways to use cannabis, implicitly to avoid COVID-19 infection, such as, “Opt for non-invasive forms of ingestion – edibles, tinctures, drinks, soft gels” and “Do not share cannabis joints, vapes or edibles.” One dispensary suggested cannabis use for anxiety, “If you are experiencing anxiety, consider using products with CBD, THCA, CBN, or low doses of THC” and this dispensary also suggested bulk purchases as a way to mitigate COVID-19 infection risk, “Limit your need to travel by stocking up on your supply. We are offering a 10% discount when you buy 4 eighths or 4 extracts , stackable with our senior and veteran discounts.” 44% of Reno websites included general statements about the importance of their patrons’ health, while general statements were found on only 16% of Bay Area websites. However, all announcements that recommended specific ways to use cannabis to mitigate COVID-19 risk or anxiety were from Bay Area dispensaries. One Bay Area dispensary asked patrons to contact local county supervisors to advocate for cannabis as an essential service and provided links. A minority of sites in San Francisco/Alameda Counties offered COVID-19 discounts or specials, including a “heroes discount” for health workers, and discounts for those laid-off from work. One San Francisco dispensary sold surgical masks and hand sanitizer.This is, to the best of our knowledge, the first study describing the novel COVID-19- related marketing communications from cannabis dispensaries during stay-at-home orders. We found that like other businesses, most cannabis dispensaries implemented operational changes, including delivery, pickup, and sanitation measures and made general statements that health and safety was important to them. In addition, however, we found some announcements on dispensary websites that were more unique to cannabis sales, such as those that linked cannabis and health, either by referring to cannabis as medicine, making references to government or health authorities, and utilizing rhetoric similar to healthcare providers, including making recommendations for cannabis forms to reduce disease transmission risk or strains to use if one was experiencing anxiety.