A Burning Problem: Cannabis Lessons Learned from Colorado

Abstract

With recent increases in cannabis’ popularity, including being legalized in several states, new issues have emerged related to use. Increases in the number of users, new products, and home growing all present distinct concerns. In the present review, we explored various cannabis-related concerns (i.e. use, acquiring, growing, and public health/policy) that have arisen in Colorado in order to provide information on emerging issues and future directions to mitigate negative outcomes that could occur in states considering, or that already have implemented, a legalized cannabis market. Specific to Colorado, issues have arisen related to edibles, vaporizers/‘e-cannabis’, concentrates, growing, quantifying use, intoxicated driving, and arrests. Understanding cannabis dosing (including dose-dependent effects and related consequences), standardizing quantities, evaluating the safety of new products, and developing harm reduction interventions are important next steps for informing public policy and promoting health and well-being. Overall, increasing our knowledge of emerging issues related to cannabis is key to promoting the benefits and combating the potential harms of cannabis, especially for states legalizing medical or recreational cannabis.

Over the past decade, cannabis has gained renewed popularity in the United States (Hasin et al. 2015). As recreational and medicinal legalization spread across the country (Pacula & Sevigny 2015), there has been an increase of users, with a legal industry forming to fill new market demands. In turn, cannabis products, such as edibles, high potency cannabis and concentrates (i.e. ‘dabs’, hash oil), electronic vaporizer pens (i.e. ‘e-cannabis’), and home growing supplies have become more widely available. Many issues regarding using, acquiring, and growing cannabis present potential public health concerns. In the present review, we explore various cannabis-related concerns (i.e. using, acquiring, growing, and public health/policy) that have arisen in Colorado. Although there are several other issues related to legalization, concerns covered in this review were selected as they are of significant public health concern, have emerged as prominent issues following legalization (or legalization has exacerbated preexisting concerns), and have available information regarding their impact. Topics covered begin at the individual use level, expand to the acquisition level, and conclude with broader public health and policy concerns. Using Colorado as an example of the changes that can be expected following legalization of recreational cannabis use, we consider the steps that can be taken to mitigate adverse outcomes that could likely occur in any state considering legalization (and potentially states that have already opened a legal cannabis market).

Issues related to using

User prevalence in Colorado has changed since recreational legalization in 2014. Past 30-day prevalence of use among adults 18 and older increased across Colorado from 2006 to 2014 and is 6–10% higher than the national average (Reed 2016). Furthermore, perceived risk of use has decreased among adolescents and adults, with risk perceptions lower in Colorado than the national average (Center for Behavioral Health Statistics and Quality [CBHSQ] 2016; Reed 2016). Similarly, findings extending through 2015 indicate cannabis use has increased among both youth and adults in Colorado since legalization (CBHSQ 2016). Moreover, higher use was reported at Colorado State University compared to nine other universities in various states without legal recreational cannabis, in terms of absolute values (i.e. this difference was not statistically tested; Pearson et al. 2017). Currently, Colorado claims the highest cannabis use in all age groups compared to all other US states (CBHSQ 2016).

With more people trying cannabis, distinct issues may arise with different forms of cannabis use (e.g. edibles, high potency cannabis and concentrates, e-cannabis) and quantifying cannabis use. Further, helping individuals understand potential harms of use may mitigate adverse outcomes (e.g. ER visits). Personalized normative feedback interventions have proven efficacious in reducing alcohol use and changing related perceptions (Neighbors et al. 2010). Similar interventions on cannabis have been tested, however limited research currently exists validating their use (e.g. Lee et al. 2010). Though not all anxious, paranoid, or otherwise unpleasant reactions to cannabis may be avoided, understanding proper dosing may help reduce accidental over-consumption (which is more likely to induce discomfort; MacCoun & Mello 2015). Interventions providing more information on harm reduction strategies (e.g. pamphlets at dispensaries) should be developed and assessed.

Issues with edibles

Cannabis-infused edibles have become popular in states with legal cannabis markets. In conjunction, reports of unintended accidents surrounding their use have arisen. Some people do not know that onset of the intoxicating effect from oral tetrahydrocannabinol (THC) ingestion may take up to 2 hours (Hancock-Allen et al. 2015), leading these individuals to consume greater amounts of edibles than intended. Large doses of THC increase risk for anxiety, paranoia, and other adverse reactions (MacCoun & Mello 2015). A report of a man who jumped to his death after ingesting over 6 times the recommended THC dose exemplifies the extreme outcomes of heavy intoxication (Hancock-Allen et al. 2015).

Edibles have other causes for concern including dosage accuracy. A test of 75 different retail products found only 17% to contain the stated dose, with 23% containing more than the stated dose, and 60% containing less than the stated dose (Vandrey et al. 2015). Other tests have found similar discrepancies (Baca 2014). Incorrectly labeled products may lead to unintentional overconsumption and adverse reactions. Further, cannabis candies and treats may also be consumed unintentionally by adults, children, or pets. Many THC-infused candies purposefully mimic common nonintoxicating candies (MacCoun & Mello 2015). Similar mimicry occurs with drinks, baked goods, ice cream, and more. Outside of its packaging, a cannabis-infused candy may be indistinguishable from regular candy. This problem is even worse for baked goods and beverages, which are more difficult to uniquely mark once outside their packaging. Cases of edibles ingestion in youth under the age of 12 doubled to 16 cases in Colorado in 2014 (Rocky Mountain High Intensity Drug Trafficking Area 2015). Moreover, the number of reported cannabis exposures in children under 5 steadily increased from 4 in 2008 to 38 in 2014. There has been a similar increasing trend of dog hospitalizations due to cannabis toxicity (Meola et al. 2012; Michel & Torres 2016).

In response to many of these concerns, regulations were passed in Colorado to decrease unintentional outcomes. First, the Colorado Retail Marijuana Code was amended to require all edibles to be marked with a ‘standard symbol indicating that it contains cannabis and is not for consumption by children’ (Retail Marijuana Code 2015). Next, changes to packaging were required, including child resistant, opaque, resealable, and more clearly labeled containers. Limits were also placed on THC concentration, including 10 mg maximum per serving (i.e. a chocolate square, a gummy bear, etc.), and a 100 mg maximum per any single product (i.e. chocolate bar, container of gummy bears, etc.). While these changes address many concerns, there are still many unaddressed issues. Future research should address dose-dependent effects of edibles to help establish better use guidelines and minimize unintentional over-intoxication. For example, since edible strength (i.e. mg of THC) is labeled on recreational packaging, comparing dose amount, subjective intoxication, and consequences of use can help establish safety guidelines. Research and policy changes can help increase quality control to establish more reliable and accurate dosing of edibles, and potentially address additional ways to avoid accidental intoxication, particularly for children and pets.

Issues with concentrates, hash, and ‘dabs’

Potency of cannabis and related products have increased over the past several years. Average THC concentrations in cannabis have increased steadily from 1995 to 2015 nationally (RMHIDT 2015; Raber et al. 2015; Prichard 2015). In 2007, the highest THC concentration found in ‘dabs’ was almost 53%, with the national average around 25% (Brenneisen 2007; RMHIDT 2015). By 2013, average hash oil in US had reached approximately 53% THC. More recent hash oil studies have found concentrations over 75%, with new extraction methods boasting concentrations as high as 90% THC (Raber et al. 2015; Prichard 2015). An ounce of average dispensary-grade concentrates may contain over four times the amount of THC compared to average dispensarygrade cannabis (Orens et al. 2015). Despite this discrepancy, Colorado law, which permits adults to possess up to one ounce of cannabis products, does not currently differentiate by product type or concentration (Colorado Const. Art XVIII § 16 2012). Higher potency cannabis and hash have both been linked to higher tolerance and withdrawal symptoms, as well as increased risk for dependence (Loflin & Earleywine 2014).

To address this concern, there are several issues on which future research and policy can focus. First, establishing standardized dosing may help inform better possession limits, accounting for potency differences (see Issues with Quantifying Use). Further, as potency varies, clear labeling should be implemented with percent concentration and recommended dosing. Next, interventions should be designed to encourage use of concentrates from dispensaries in lieu of homemade products. Doing so may help minimize inhalation of harmful contaminates and potential harms from production (see Issues with Manufacturing and Contamination). Finally, while limited research exists, more research will be needed examining the long-term safety of concentrates, as well as unique outcomes related to ‘dabbing’ and other concentrate use.

Issues with vaping

Portable electronic cannabis vaporizers are another popular product that use cannabis concentrates. While vaporization may minimize some harmful effects of smoking, it poses unique risks (Earleywine & Barnwell 2007). Concealable vaporizers have minimal smell and make use in public less detectable, creating a way for youth, among others, to hide cannabis use (Bryan 2014). The decreased stigma and ease of use may also promote initiation of use. Use of e-cannabis has reached high school students, with approximately 5.4% having tried it (18.4% of cannabis users) (Morean et al. 2015). Younger cannabis initiation is related to higher dependence rates (Volkow et al. 2014). Portable vaporizer use may enable users to conceal use from friends, parents, and others, which can exacerbate problematic use.

Future directions addressing these concerns should include interventions targeting underage and problematic use including vaping safety. For tobacco, interventions deglamorizing use have been found to result in reductions in underage use (e.g. ‘Tobacco Unfiltered Reality’, Kandra et al. 2013). Similar interventions may help combat the decreasing perceived risk of e-cannabis use among adolescents. Moreover, research should better establish acute and longterm effects of e-cannabis use, especially related to the various chemicals used in production and consequences unique to e-cannabis. Lastly, using more accurate dosage labeling, not relying on total weights but instead potency or THC weight, including recommended dosing (e.g. ‘three puffs ¼ one 5 mg dose’), will better inform users and promote safer consumption. Research examining differences in use and outcomes based on product labeling may prove beneficial in evaluating efficacy of these proposed changes.

Issues quantifying use

Given the plethora of cannabis products with ranging potencies, in conjunction with unreliable concentration testing and limited past research, quantifying use has been a longstanding difficulty. Unlike drinking, where alcohol researchers are able to measure the standard drink (i.e. 12 oz. beer, 4 oz. wine, 1.5 oz. liquor), there is no standard joint for cannabis researchers. Moreover, the potency of cannabis is often unknown to the user, especially when homegrown or purchased illegally. The rise in use of edibles poses other challenges to quantifying cannabis use (i.e. different rates of absorption).

Some past research has attempted to quantify the number of grams, number of joints, or number of hits consumed (e.g. Freeman & Winstock 2015). Other studies have adapted the Opiate Treatment Index (OPI; Darke et al. 1991) to compute a Q score, which is derived by calculating the number of hits taken on recent use episodes and the number of days between use episodes. To date, there appears to be no momentum behind a specific strategy to capture quantity of cannabis use.

Future research is needed to compare methods and establish standards for measuring cannabis quantity. To support such studies, experimental studies (e.g. randomized trials) should be performed establishing a clearer understanding of dose and route of administration dependent effects. While alcohol is known to have dose-dependent effects and consequences, the same is largely unknown for cannabis, mostly due to issues with quantifying use. Better understanding of cannabis quantity and dosing will provide a basis for understanding effects at varying doses and establishing safety guidelines and limits (e.g. edibles, concentrates). Although these issues will continue to plague cannabis researchers for some time, legalization and increases in regulation may improve researchers’ ability to operationalize cannabis use quantity in a standardized manner. For example, the distribution of cannabis in standard sizes and weights will improve an individual’s ability to report more precisely how much cannabis they consume, which is necessary to more accurately quantify the dosedependent effects of cannabis.

Issues related to acquisition, growing, and contamination of cannabis

Issues with acquisition

Availability may have increased due to general trends of cannabis price reduction. From Fall 2014 to Summer 2015, prices in Denver recreational dispensaries fell 15–25% (Chin 2015). Despite legal dispensaries and falling prices, Colorado still has an active cannabis black market (Light et al. 2014; RMHIDT 2015; Subritzkey et al. 2016). In 2016, 24% of college students reported obtaining their cannabis from black market purchases, up from 18% in 2015 (RMHIDT 2015). In comparison, 45% acquire it through friends who obtain it legally, up from 29% in 2015. Availability to other states has also increased since legalization. From 2010 to 2014, the number of seized packages shipped from Colorado to another state containing cannabis ballooned from 15 to 320 per year (RMHIDT 2015). Apprehended packages in 2014 totaled 470 pounds of cannabis; however, the amounts that reached their destinations undisturbed is unknown.

Colorado has taken steps to help limit black market trade. In 2017, Colorado lowered cannabis taxes to compete with black market prices (Wood 2015). Similarly, a newly legalized state, Oregon, implemented a tax significantly lower than Colorado’s current tax rate in efforts to fight the illegal market. Future research should examine how differences in taxation impact black market activity. Colorado also employs the Marijuana Enforcement Tracking Reporting and Compliance (METRC) system, which tracks cannabis from ‘seed-to-sale’ (i.e. all stages of production and distribution; Brohl et al. 2014). Committed to effective regulation, Colorado doubled METRC staffing and office locations over the first year of retail sales. MERTC staff provide quarterly reports, starting in 2014, detailing the legal cannabis market. Research should examine the effectiveness of a tracking system, including continued comparisons with amounts supplied legally to help estimate black market size.

Issues with growing cannabis

State laws vary on legality of growing cannabis (National Organization for the Reform of Marijuana Laws 2016). Although growing illegally poses unique risks, legal growing has dangers as well. In states where it is legal to grow, supplies are more accessible; however, no laws exist regulating safe home growing (Colorado Const. Art XVIII § 16 2012). Novel growers may be uninformed and not know which pesticides to use and how to prevent bacterial or mold growth (Martyny et al. 2013). Some molds and bacteria can be hazardous to one’s health, both as a grower and/or consumer of the plant. Testing samples from illegal grow operations found that almost half of the plants had harmful mold, and two-thirds had harmful bacterial growths (Martyny et al. 2013).

Grow rooms require lower ventilation to allow for higher carbon dioxide levels (Martyny et al. 2013). High levels of carbon dioxide are potentially dangerous, and low ventilation can allow for chemical and moisture buildup in the air, the latter promoting the growth of mold and bacteria. The fertilizers and chemicals used for growing cannabis are not exceptionally dangerous if properly used (Martyny et al. 2013). Improper handling or ingestion of some can be toxic, which is particularly important for grow areas or supplies that are accessible to children or pets.

By attending to these growing concerns, negative consequences may be diminished. Studying the home-growing community, monitoring cultivation-related hospital visits, and identifying implicated hazards and risk factors are all potential steps researchers can take to minimize harm. As research establishes safe cultivation guidelines, states should adapt policies congruent with empirical recommendations. Moreover, although a multitude of cannabis growing guides exist (e.g. Green 2009; Rosenthal 2010), accessible information should be provided to home growers based on established safety procedures. Designing and evaluating interventions to increase grower safety knowledge may help minimize related concerns.

Issues with contamination of cannabis

There are many steps to growing that can lead to potentially harmful side effects. For retail and medicinal cannabis, most states have regulations in place for pesticides and microorganisms. However, a Colorado company was brought to court for using a pesticide that becomes toxic when heated (Flores v. LivWell 2015). Studies have shown that pesticides are able to transfer from smoked plant material to humans, which can lead to various health issues (Sullivan et al. 2013). State regulations for pesticides range from none to specific parts-per-million (ppm) measurements (Feldman 2015). States that do not have regulations may be putting users at risk. Moreover, illegal operations have no regulation for the pesticides and other chemicals used. Contamination issues arise for each method of consumption (e.g. smoked, eaten, concentrated). For example, in 2015 three Colorado companies recalled over 30,000 edibles due to pesticide contamination (Baca & Migoya 2015b). The companies blamed dishonest suppliers, which may implicate a larger issue regarding growing regulations and oversight of the cannabis growing industry.

Other contamination concerns relate to the production of hash oils. Contamination with various chemicals, such as butane or pesticides, remain a central concern for hash oil production (Raber et al. 2015). More than 80% of California dispensary samples tested by Raber et al. (2015) were found to be contaminated with solvents (i.e. butane, heptane, isopropyl alcohol, etc.) and/or pesticides. Recalls for pesticide contamination in hash oil have already happened in Colorado (Baca & Migoya 2015a). Impurities in concentrates have been implicated in various toxic effects (Raber et al. 2015). Although Colorado has regulations on residual solvent and pesticide contamination in retail hash oil, homemade products have no such oversight (Retail Marijuana Code 2015). Butane, a common solvent for making hash oil, poses additional risks. Butane-based concentrates use and release large quantities of butane during production (Damuzi 2004). Production in areas with lower ventilation pose risks of butane inhalation, which can include disorienting effects. Moreover, butane’s highly flammable nature increases risk of explosions. In 2014, THC extraction lab explosions more than doubled to 32, resulting in 30 injuries, including 17 hospitalizations (RMHIDT 2015). There are also several reports of individuals hospitalized or dead due to butane explosions while making hash oil in their homes (e.g. Risling 2013; Damuzi 2004).

Manufacturing THC extracts for e-cannabis vaporizers is a complex process that also lacks quality control, including storage issues, accurate dosages, purity, and more (Giroud et al. 2015). Additionally, higher temperature vaporization has been found to release formaldehyde from propylene glycol and glycerol, common e-cigarette ingredients (Jensen et al. 2015). Some THC solutions, both home-made and retail, contain these chemicals as well, which may lead to formaldehyde formation (Misuraca & Hayes 2014). Inhaling formaldehyde can increase risk of cancer formation (Jensen et al. 2015). Additionally, since THC extract potency is varied, cartridges containing equal mass of solution contain differing amounts of THC (Misuraca & Hayes 2014). This variability can create issues regulating dosing, particularly as extracts are sold by total mass, not just THC mass.

As research establishes safe pesticide use and bacterial/ mold avoidance, states should adapt policies congruent with empirical recommendations. For example, research has begun to identify safer ways to produce concentrates that does not involve flammable and toxic solvents (Prichard 2015). Other less hazardous alternatives as well as better decontamination processes to currently used toxins should be investigated and developed. Policy changes to ensure worker and user safety with safer production techniques may be advantageous.

Issues related to public health & policy

Colorado cannabis-related emergency room (ER) visits (29%) and hospitalizations (38%) both rose in 2014, the year retail cannabis became available (RMHIDT 2015). Most ER visits were due to anxious reactions to the drug, typically following consumption of a large amount of THC (Hesse 2016). Higher THC concentrations, mislabeled products, and uninformed consumers may all increase risk for adverse reaction leading to ER visits. Cannabis use may also pose a threat to those around the user. Animal studies indicate secondhand cannabis smoke adversely impacts blood vessel functioning similar to tobacco smoke, with functional impairment persisting longer than tobacco’s impairment (Wang et al. 2016). Beyond ER visits, other public health/ policy concerns have arisen (i.e. workplace dynamics, intoxicated driving, and arrests).

Issues in the workplace

Cannabis use and the workplace has become a controversial issue. Approximately 6.4% of full-time employees report past month cannabis use, with 1.45% reporting use within 2 hours of work, and 0.67–0.89% using while at work or on break (Frone 2006; Larson et al. 2007). From 2012 to 2013, positive workplace cannabis drug tests increased by 6.2% nationwide and 20% in Colorado (Quest Diagnostics 2014). This trend continued nationwide as positive workplace cannabis drug tests increased 25% from 2014 to 2015 (Quest Diagnostics 2016). While risk of accident is a concern, positive screenings post-accident did not differ from random screenings, indicating users are not more likely to have used prior to an accident than other days (Price 2014).

Despite its legal status, the Colorado Supreme Court ruled that workers can still be fired for using cannabis while not at work as it is federally illegal (Coats v. DISH Network, LLC 2015). In many other states, the issue is still undecided such that states vary in the protection of employee rights (Olafson 2016). Some argue that medicinal use falls under protection from the Americans with Disabilities Act of 1990 (Americans with Disabilities Act 1990), and thus must be allowed. Legal cannabis use is also making federal job recruitment difficult, as many jobs (e.g. CIA, FBI) require that applicants have years of abstinence before being hired (Rosenberg & Mazzetti 2015). As more states legalize cannabis this issue will have to be addressed in light of best workplace safety practices. For example, using blood testing instead of urine testing is a more proximal approximation of intoxication and may help differentiate currently intoxicated workers from those who recently used (Phillips et al. 2015). Additionally, understanding dose-dependent effects may help establish better workplace safety guidelines, particularly for those medicating with cannabis.

Issues with intoxicated driving

Another rising concern is driving while under the influence of cannabis (DUIC; Asbridge et al. 2012; Hall 2012; Hartman & Huestis 2013; Whitehill et al. 2014; Le Strat et al. 2015), with rates of DUIC showing a steady increase throughout many countries (see Asbridge et al. 2012 for brief overview). Within the United States, the prevalence of nighttime DUIC has increased by 48% from 2007 to 2014 (Berning et al. 2015). Compared to drunk driving which has shown a significant decrease over time, the prevalence of DUIC has not significantly changed from 2002 to 2014 (Azofeifa et al. 2015). Further, cannabis use (in particular recent cannabis use) has been implicated as a major risk factor for motor vehicle crashes (Ramaekers et al. 2004, 2009). In a recent meta-analysis across nine epidemiological studies, Li and colleagues (Li et al. 2012) found that drivers who drove under the influence of cannabis were more than twice as likely as other drivers to be involved in motor vehicle crashes (odds ratio ¼ 2.66).

In Colorado, while DUICs decreased by 1% from 2014 to 2015, there was a 12% increase in concurrent cannabis use among all driving under the influence (DUI) arrests (Reed 2016). Moreover, THC was implicated in 44% more DUI driver fatalities in the same time period, though presence of THC does not necessarily indicate present intoxication (Reed 2016). A limit does exist for permitted cannabis use prior to driving in Colorado, however, there is no consensus on adequate roadside cannabinoid testing (Wille et al. 2010). Further, difficulties quantifying use, individual differences between users, and inconsistent findings relating cannabis dose and traffic accidents have made it difficult to set standard policies and laws against DUIC (Sewell et al. 2009; Armentano 2012; Masten & Guenzburger 2014; Neavyn et al. 2014; Wong et al. 2014; Anderson & Rees 2015). Some research points to greater driving impairment among infrequent users compared to more experienced users, who are able to better compensate for deficits (Sewell et al. 2009; Neavyn et al. 2014). Nonetheless, researchers and advocacy groups, including NORML, advocate that cannabis users should not operate motor vehicles in an impaired state (Sewell et al. 2009; Armentano 2012; Neavyn et al. 2014; Wong et al. 2014). Although police enforcement strategies (e.g. random roadside testing) are effective for reducing drunk driving (Chisholm et al. 2004; Anderson et al. 2009), there are few studies examining efficacy of these strategies on DUIC reduction. Major hurdles in analyzing the effectiveness of police enforcement strategies include: 1) varying approaches towards DUIC laws (Wolff & Johnston 2014; Wong et al. 2014), 2) no standard measures (e.g. blood, urine, oral) for detecting impaired driving (Wille et al. 2010), and 3) inconclusive data as to how long after consuming cannabis impairment persists (Sewell et al. 2009). Standardized legislation and development of more accurate measures to detect impairment will be essential to reduce DUIC.

Despite risks, many cannabis users do not perceive DUIC as a major risk, especially compared to drunk driving (Davis et al. 2016). Based on this finding, more research is needed on educating cannabis users of the potential risks of DUIC. A harm-reduction approach (e.g. use of a designated driver) may be efficacious given its utility in the alcohol literature (Pearson 2013; Prince et al. 2013). Further, given that cannabis and alcohol have additive effects on impaired driving and there has been an increase in cannabis-in-combination DUIs (Ronen et al. 2008, 2010; Downey et al. 2013; Hartman et al. 2015; Reed 2016), community prevention strategies may target both substances in order to reduce driving under the influence.

Additionally, ‘brief interventions’ focusing on reducing alcohol consumption and frequency have shown consistent secondary benefits in reducing drunk driving (Steinka-Fry et al. 2015). Fischer et al. (2013) found a reduction in DUIC for high-frequency users in combined written and oral brief intervention groups, as opposed to control groups. Based on these findings, brief interventions may be a cost-effective strategy to reduce DUIC. Finally, one approach that has been promising is increasing the likelihood of apprehension as opposed to severity of the penalty (Nagin et al. 2015). Jones et al. (2006) found that cannabis users were less likely to DUIC if there was a high likelihood of apprehension, while severity of punishment had no influence on likelihood of DUIC. However, this finding should be replicated longitudinally to evaluate for lasting effects.

Issues related to arrests

From 2012 to 2014, all cannabis-related arrests in Colorado declined by 46% (Reed 2016). In that same time period, cannabis went from accounting for 6% of all arrests to 3% of all arrests. These decreases allow for reallocation of police efforts, court proceedings, and taxpayer expenses. Divided by race, cannabis-related arrests decreased by half among Whites, a third among Hispanics, and a quarter among Blacks (Reed 2016). Although there is a steady decrease in total arrests across racial groups, there is a discrepancy in arrest rates between Blacks and Whites. Currently, Black individuals are three times more likely to be arrested for a cannabis-related offense than White individuals in Colorado (Reed 2016). Yet, when examining Colorado use rates, Black individuals report only slightly higher use (19.2%) in the past month compared to Whites (14.1%), and make up significantly less of the population (72.3% White, 3.8% Black; Reed 2016). This troubling inconsistency brings into question the unequal enforcement of cannabis laws, with minority individuals continuing to be disproportionately subjected to repercussions.

Despite overall decreases in arrests, a 5% increase cannabis-related arrests among adolescents was noted from 2012 to 2014 (Reed 2016). Although this increase may be due to shifts in police enforcement, it may also reflect increases in underage use (RMHIDT 2015). Discrepant with this increase, White youth arrests decreased by 8% during that time period, while Hispanic juvenile arrests increased by 29%, and Black youth arrests by 58% (Reed 2016). Nationally, past month use among 8th to 12th graders was approximately 3% higher among Blacks, while lifetime use ranges from 5% higher to equivalent between the two races (Miech et al. 2015). This mirrors discriminatory cannabis arrest practices noted in the general Colorado population (Reed 2016). These biased arrest practices call for an examination of police enforcement strategies.

Conclusions

Cannabis legalization with a retail market is still novel and evolving in the United States. Although many of the issues that have arisen have been addressed, many unresolved issues remain. Unforeseen problems will begin to surface as legalization spreads (e.g. four additional states legalized recreational cannabis in 2016), technology improves, and perceptions toward cannabis use continue to change. Future research will be essential for ensuring public health. Understanding cannabis dosing (including dose-dependent effects and related consequences), standardizing quantities, evaluating the safety of new products, and developing harm reduction interventions are important next steps. Moreover, research findings should be used to inform public policy and promote health and wellbeing, especially for states legalizing medical or recreational cannabis. Though it is currently understudied, increases in our knowledge is key to promoting the benefits and combatting the potential harms of cannabis.