Research paperSmoking, vaping, eating: Is legalization impacting the way people use cannabis?☆
Introduction
Close to half of states in the United States allow in-state procurement and consumption of cannabis for medical or compassionate purposes (National Conference of State Legislatures, 2015, ProCon.org, 2015b), four states also allow for recreational use, and more states are considering similar legislation (ProCon.org, 2015a, ProCon.org, 2015c). Misuse of cannabis can have a variety of negative effects on users (Hall, 2009) and in states where cannabis is medically legal, individuals appear to have a higher likelihood of cannabis use and report lower perceived risk associated with cannabis use (Cerda et al., 2012, Wall et al., 2011). Other studies, however, suggest that medical marijuana laws (MML) have little impact on the prevalence of current use status (Choo et al., 2014, Harper et al., 2012, Hasin et al., 2015, Lynne-Landsman et al., 2013). One important component of medical cannabis legalization that has yet to be explored is the relationship between MMLs and the methods that individuals use to consume cannabis.
There are a variety of ways to consume cannabis (Schauer, King, Bunnell, Promoff, & McAfee, 2016). The three most common methods are inhalation via smoking, inhalation via vaporization (vaping), and ingestion of edible products. The method of administration can impact the onset, intensity, and duration of psychoactive effects, effects on organ systems, and the addictive potential and negative consequences associated with use (Julien, 1995). With smoked cannabis, the psychoactive effects and peak THC blood levels occur in minutes, and the effects last approximately 1–4 h (Huestis et al., 1992a, Huestis et al., 1992b, Huestis et al., 1992a, Huestis et al., 1992b, Lemberger et al., 1972). Vaping, defined as “using electricity to heat cannabis products so that the cannabis resin is released as a vapor that is inhaled,” (Malouff, Rooke, & Copeland, 2014) has a similar onset, peak, and duration as smoking and produces a similar high (Abrams et al., 2007). Eating cannabis (edibles) produces a different pharmacokinetic profile than smoking or vaping (Aggarwal et al., 2007, Carter et al., 2004). Onset of the effect is delayed to approximately 30–60 min (Lemberger et al., 1972), peak blood levels of THC occur approximately 3 h later (Lemberger et al., 1972), and the effects can last over 6 h (Lemberger et al., 1972).
Method of administration of cannabis can also have differential impact on the user's health. Smoking allows the user to more effectively self-titrate the dose and desired level of intoxication (Carter et al., 2004) but portends inhalation of carcinogenic materials and adverse effects on respiratory health (Aldington et al., 2007, Tetrault et al., 2007, Wu et al., 1988). Additionally, enlisting multiple ways of smoking cannabis (e.g., joints, pipes, bongs) is associated with greater probability of problematic use or dependence (Baggio et al., 2014, Chabrol et al., 2003). The long-term health consequences of regularly vaping cannabis are not known but vaping may minimize impact on respiratory function compared with smoking cannabis by reducing the inhalation of combustible smoke and its carcinogenic constituents (Abrams et al., 2007, Gieringer, 2001, Hazekamp et al., 2006, Pomahacova et al., 2009, Van Dam and Earleywine, 2010). People may prefer vaping instead of smoking as their primary method of administration as it is reported to be a better tasting, more efficient, and cost-effective way to obtain the desired euphoric effect (Budney et al., 2015, Malouff et al., 2014). These “positive” aspects of vaping and the perception of reduced respiratory system harm could conceivably lead to more frequent consumption or earlier initiation of cannabis, and a concomitant increased risk of developing problematic use or addiction (Budney et al., 2015). Edibles also allow the user to avoid inhaling smoke; however, it is harder to titrate the intoxicating effects due to the delayed and variable onset of effects. Consequently, edibles have recently been tied to cannabis “overdose” following ingestion of additional doses because of the misperception that the initial dose had not produced the desired effect (Ghosh et al., 2015, MacCoun and Mello, 2015). Availability of edibles has also been associated with increased rates of accidental pediatric ingestion of cannabis and associated adverse effects (Ghosh et al., 2015, Wang et al., 2013, Wang et al., 2014).
The regulation of medical cannabis across the United States is marked by extreme legislative and regulatory heterogeneity. Medical marijuana laws enacted to address the dispensation and consumption of cannabis for medical purposes have been in place for over a decade in some states and only a few years in others (ProCon.org, 2015b). Additionally, some MML states, but not all, have developed state regulated cannabis dispensary systems (i.e., stores or “pharmacies”) that provide access to novel cannabis products such as vaporizers and edibles. Dispensaries have been linked with availability of higher potency (% THC) cannabis (Ghosh et al., 2015, Sevigny et al., 2014) increased cannabis related hospitalizations (Mair, Freisthler, Ponicki, & Gaidus, 2015), and the sale of cannabis products with highly inaccurate labeling of the active ingredients in cannabis (e.g., %THC and cannabidiol) (Vandrey et al., 2015). Among the MML states that allow for dispensaries, the number of dispensaries varies greatly, with hundreds of dispensaries permitted in some states to only a handful permitted in others (Colorado Department of Revenue Enforcement Division, 2015, State of New Jersey Department of Health, in press). Consequently, states that have had an MML in place for longer periods of time do not necessarily have more dispensaries.
Legalization of cannabis use and the sale of cannabis most likely prompt increased development, production, and marketing of desirable cannabis products and delivery systems to increase sales and meet consumer demand (Colorado Department of Revenue Enforcement Division, 2015, Ghosh et al., 2015). The goal of the present study was to explore how the existence of MMLs and differing MML dispensary policies are related to three methods of cannabis administration – smoking, vaping, and edibles. Specifically, we examined three aspects of legalization status across states, (1) MML status (yes or no); (2) the duration of time a state has had an MML in place; and (3) the density of cannabis dispensaries within each state. Primary hypotheses were that having an MML, increased duration of MML status, and higher density of dispensaries would be associated with increased likelihood of ever use, preference for, and younger age of initiation of the less common methods of cannabis administration (i.e., vaping and edibles).
Section snippets
Survey and recruitment
The Dartmouth Committee for the Protection of Human Subjects approved the study. A survey was administered using Facebook paid advertising mechanisms to target and recruit a self-selected convenience sample of cannabis users. Advertisements for the survey were shown to a targeted audience of cannabis users through the use of proprietary marketing algorithms that utilize Facebook users’ self-reported interests. Examples of cannabis-related interests included association with organizations such
Description of the sample
Advertisements were shown to 168,894 people out of whom 3708 (2.2%) clicked the link, and of which 2838 (1.7%) passed the data-quality check question, completed the survey, reported use of cannabis in their lifetime and reported the state in which they lived. Table 1 displays detailed characteristics of the sample. The mean age was 32.5 years (SD = 15.5), 84.5% were male, and the race/ethnicity distribution was 74.4% Caucasian, 14.6% Hispanic or Latino, 7.5% African American and 3.5% Other.
Discussion
Findings from this convenience sample of cannabis users support the hypotheses that vaping and use of edible cannabis appear more prevalent in states with MMLs, in states that have had MMLs in place for a longer time, and in MML states with a higher per capita density of cannabis dispensaries. If future investigations find these relationships to be causal, that is, MMLs do change how cannabis is used, then legislators and policy makers in the United States and other countries should be aware of
Funding
The funding sources had no involvement in the study design; collection, analysis and interpretation of data; writing of the report; or in the decision to submit the article for publication.
Conflict of interest
All authors have no conflicts of interest to report.
Acknowledgments
NIH 5T32DA037202-02, 5R01DA032243-04 & P30DA029926.
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Portions of this work were previously presented at the College on Problems for Drug dependence conference in Phoenix Arizona, June 2015.