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Background: Cannabis policy has shifted toward legalization in many parts of the United States (US). While attention has been focused on whether legalization will lead to changes in cannabis use, it is conceivable that legalization will also affect use of substances that individuals frequently use with cannabis. This study assessed whether cannabis legalization impacted the prevalence of poly use of cannabis and alcohol from 2004 to 2017 and estimated the prevalence of cannabis and alcohol poly use in 2017., Methods: Public and restricted-use data from the US 2004-2017 National Survey on Drug Use and Health were analyzed. Data on past-month cannabis and alcohol use were assessed each year. Cannabis legalization was determined by the presence or absence of medical marijuana laws (MML) and recreational marijuana laws (RML) in each state. Difference-in-difference approach was used to estimate the association of MML and RML on cannabis and alcohol use overall and by sociodemographic subgroups (e.g., age, income, education)., Results: Between 2004 and 2017, poly use of cannabis and alcohol increased while alcohol-only use decreased. MML were associated with increases in poly use only among adults over age 50 and among those with higher annual incomes and higher education, while RML were associated with increases in poly use broadly among adults across sociodemographic groups., Conclusions: Legalization of cannabis was associated with increases in cannabis-alcohol poly use in the US. RML were associated with increases across demographics, while the impact of MML was more limited to certain sociodemographic groups., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Little information exists about cannabis use and its correlates among workers, particularly use before or at work, which may impact occupational safety. This study explores overall and workplace cannabis use patterns before legalization among Canadian workers and estimates the associations of personal and work-related characteristics with workplace and non-workplace cannabis use., Methods: Cross-sectional data were collected from 1651 Canadian workers in June 2018. The primary outcome was past-year cannabis use pattern: use, including before/at work (past-year workplace use); use, but not before/at work (past-year non-workplace use); no past-year use (non-past-year use). The associations of personal (sociodemographic, health) and work-related factors with workplace and non-workplace cannabis use were estimated using multinomial logistic regression., Results: A quarter of respondents reporting past-year cannabis use used cannabis before and/or at work. Respondents reporting workplace use were more likely to report more frequent cannabis use, use for medical or mixed purposes, and high THC cannabis use than workers reporting non-workplace use. Several personal factors were positively associated with workplace and non-workplace use (e.g., younger age, lower education). A safety-sensitive job, drug testing, supervisor role, less job visibility, lower perceived ability of supervisors to identify use/impairment, and less restrictive workplace smoking policies were positively associated with workplace use only., Conclusions: A non-trivial proportion of workers reported workplace use, but the nature of this use is complex. Work-related factors addressing the likelihood of detection and being in a safety-sensitive job were associated with workplace use. Worker education on lower risk use appears warranted., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Cannabis use and cannabis use disorder are more prevalent in U.S. states with medical marijuana laws (MMLs), as well as among individuals with elevated psychological distress. We investigated whether adults with moderate and serious psychological distress experienced greater levels of cannabis use and/or disorder in states with MMLs compared to states without MMLs., Methods: National Survey of Drug Use and Health data (2013-2017) were used to compare past-month cannabis use, daily cannabis use, and cannabis use disorder prevalence among adults with moderate and serious psychological distress in states with versus without MMLs. We executed pooled multivariable logistic regression analyses to test main effects of distress, MMLs and their interaction, after adjustment., Results: Compared to states without MMLs, states with MMLs had higher adjusted prevalence of past-month use (11.1 % vs. 6.8 %), daily use (4.0 % vs. 2.2 %), and disorder (1.7 % vs. 1.2 %). Adults with moderate and serious psychological distress had greater adjusted odds of any use (AORs of 1.72 and 2.22, respectively) and of disorder (AORs of 2.17 and 2.94, respectively), compared to those with no/mild distress. We did not find evidence of an interaction between MMLs and distress category for any outcome., Conclusions: Associations between elevated distress and cannabis use patterns are no greater in states with MML. However, cannabis use is more prevalent in MML states. Thus, higher base rates of cannabis use and disorder among adults with elevated distress are proportionally magnified in these states., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Cannabis use is more common among adults with anxiety. Cannabis legalization is occurring rapidly across the United States (US) and individuals may use cannabis to cope with anxiety. This study investigated whether cannabis use across the US has changed differentially by anxiety status and by state cannabis legalization for medical (MML) and/or recreational use (RML)., Methods: Public and restricted-use data from the 2004 to 2017 National Survey on Drug Use and Health, an annual cross-sectional, nationally representative survey of US individuals, were analyzed. The prevalence of past-30-day cannabis use by anxiety status in 2017 was estimated among respondents ages ≥18 (n = 42,554) by sociodemographics and state-level cannabis law. Weighted logistic regressions with continuous year as the predictor for the linear time trend were used to examine the time trends in cannabis use by anxiety and cannabis law status from 2004 to 2017 (total combined analytic sample n = 398,967)., Results: Cannabis use was consistently two to three times higher among those with high anxiety compared to those with some or no anxiety and was higher in states with RML compared to MML or no MML/RML. Cannabis use has increased over time among those with and without anxiety overall, in MML states, and in states without MML/RML; with a faster increase in cannabis use among those with high anxiety compared to lower anxiety in states with MML., Conclusions: Cannabis use is increasing among American adults overall, yet is disproportionately common among Americans with anxiety especially among those residing in states where cannabis has been legalized., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to report., (Copyright © 2020. Published by Elsevier B.V.)

Background: Given a rapidly changing policy landscape, we sought to characterize the effects of state marijuana laws on parents' views of marijuana use by their teenage children., Methods: Data are from 595 respondents to a nationally administered, web-based survey of parents of adolescents (ages 13-18 years) with any of three chronic conditions (type 1 diabetes, rheumatic disease, attention-deficit/hyperactivity disorder). Multivariate ordinal logistic regression was used to model the effects of parents' reports of state cannabis laws on their views toward marijuana use by their child., Results: While 89.9% said any marijuana use was risky for their child, 27.9% would approve of its use if prescribed as medicine. Parents reporting marijuana decriminalization (11.1%) were more amenable to teenage use, less concerned about how marijuana might impact their child's condition, more accepting of the safety of marijuana as medicine, and approved its use with a prescription. Parents reporting legal medical (35.6%) or recreational (5.7%) use were more likely to report that their child has tried or used marijuana regularly. Parents reporting legal recreational use were less likely to agree that marijuana has medical benefits for their child., Conclusions: Among parents of medically vulnerable children, perceiving state marijuana policies as more permissive is strongly associated with lower perceived riskiness of marijuana use for their children. State marijuana policies are changing with implications for how parents of medically vulnerable youth view and potentially govern marijuana use by their medically vulnerable children., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Alternative methods for consuming cannabis (e.g., vaping and edibles) have become more popular in the wake of U.S. cannabis legalization. Specific provisions of legal cannabis laws (LCL) (e.g., dispensary regulations) may impact the likelihood that youth will use alternative methods and the age at which they first try the method - potentially magnifying or mitigating the developmental harms of cannabis use., Methods: This study examined associations between LCL provisions and how youth consume cannabis. An online cannabis use survey was distributed using Facebook advertising, and data were collected from 2630 cannabis-using youth (ages 14-18). U.S. states were coded for LCL status and various LCL provisions. Regression analyses tested associations among lifetime use and age of onset of cannabis vaping and edibles and LCL provisions., Results: Longer LCL duration (OR vaping : 2.82, 95% CI: 2.24, 3.55; OR edibles : 3.82, 95% CI: 2.96, 4.94), and higher dispensary density (OR vaping : 2.68, 95% CI: 2.12, 3.38; OR edibles : 3.31, 95% CI: 2.56, 4.26), were related to higher likelihood of trying vaping and edibles. Permitting home cultivation was related to higher likelihood (OR: 1.93, 95% CI: 1.50, 2.48) and younger age of onset (β: -0.30, 95% CI: -0.45, -0.15) of edibles., Conclusion: Specific provisions of LCL appear to impact the likelihood, and age at which, youth use alternative methods to consume cannabis. These methods may carry differential risks for initiation and escalation of cannabis use. Understanding associations between LCL provisions and methods of administration can inform the design of effective cannabis regulatory strategies., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: This study examines the relationships between trial of new marijuana or hashish products and unexpected highs, and use of edible products and unexpected highs., Methods: We conducted an online survey of 634 adult, past-year marijuana users in Colorado. We used logistic regression models to examine the relationship between new product trial or edible use and unexpected highs., Results: In the first year that recreational marijuana was legal in Colorado, 71.4% of respondents tried a new marijuana or hashish product, and 53.6% used an edible product. Trial of new products was associated with greater odds of experiencing an unexpected high after controlling for age, gender, education, mental health status, current marijuana or hashish use, and mean amount of marijuana or hashish consumed in the past month (OR=2.13, p<0.001). Individuals who reported having used edibles had greater odds of experiencing an unexpected high, after controlling for the same set of variables (OR=1.56, p<0.05)., Conclusion: People who try new marijuana or hashish products, or use edible marijuana or hashish products, are at greater risk for an unexpected high. It is possible that some negative outcomes associated with marijuana use and unexpected highs may be averted through a better understanding of how to use product packaging to communicate with consumers., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Support for the legalization of recreational marijuana continues to increase across the United States and globally. In 2016, recreational marijuana was legalized in the most populous US state of California, as well as three other states. The primary aim of this study was to examine trends in support for recreational marijuana legalization in Washington, a state which has had legal recreational marijuana for almost four years, using data collected over the four years post-legalization. A secondary aim was to examine trends in support for the cultivation of marijuana for personal use., Methods: Data come from geographically representative general population samples of adult (aged 18 and over) Washington residents collected over five timepoints (every six months) between January 2014 and April 2016 (N=4101). Random Digit Dial was used for recruitment. Statistical analyses involved bivariate comparisons of proportions across timepoints and subgroups (defined by age, gender, and marijuana user status), and multivariable logistic regression controlling for timepoint (time) to formally test for trend while controlling for demographic and substance use covariates. All analyses adjusted for probability of selection., Results: Support for legalization in Washington has significantly increased: support was 64.0% (95% CI: 61.2%-67.8%) at timepoint 1 and 77.9% (95% CI: 73.2%-81.9%) at timepoint 5. With each six months' passing, support increased 19% on average. We found no statistically significant change in support for home-growing., Conclusions: Support for marijuana legalization has continued to significantly increase in a state that has experienced the policy change for almost four years., (Copyright © 2017. Published by Elsevier B.V.)

Objectives: To assess the association between U.S. state medical marijuana laws (MML), the most liberal category of marijuana policies before legalization, their specific provisions, and adolescent past-30-day use and heavy marijuana use., Methods: This quasi-experimental study used state Youth Risk Behavior Survey (YRBS) data collected during 1991-2011 from 45 states (N=715,014) to examine MML effects, taking advantage of heterogeneity across states in MML status and design. Multiple logistic regression modeling was used to adjust for state and year effects, and youth demographics., Results: Unadjusted analyses found that MMLs were associated with higher rates of adolescent past-30-day marijuana use (odds ratio [OR]=1.08, 95% confidence interval, [(CI)=1.03,1.13]) and heavy marijuana use (OR=1.12, [CI=1.05,1.21]). However, analyses adjusting for state/year effects found a 7% lower odds of use (OR=0.99, [CI=0.98,0.999]) and no difference in heavy use. In the adjusted models, years since MML enactment (OR=0.93, [CI=0.86,0.99]) and MML inclusion of more liberalized provisions (OR=0.98, [CI=0.96,0.998]) were associated with slightly lowered odds of past-30-day marijuana use. Conversely, allowance for ≥2.5 usable marijuana ounces was associated with higher past-30-day marijuana use odds (OR=1.21, [CI=1.09,1.34]) and a voluntary vs. mandatory patient registration with higher odds of both past-30-day use (OR=1.41, [CI=1.28,1.56]) and heavy use (OR=1.23, [CI=1.08,1.40])., Conclusions: MML enactment, years since enactment, and inclusion of more liberalized provisions were not associated with increased adolescent marijuana use in this dataset after adjusting for state and year effects; however, higher possession limits and a voluntary registration were. It is possible that state norms are the impetus for MML enactment., Competing Interests: statement No conflicts of interest to report., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: Little is known on how perceived availability of marijuana is associated with medical marijuana laws. We examined the relationship between medical marijuana laws (MML) and the prevalence of past-month marijuana use, with perceived availability of marijuana., Methods: Data were from respondents included in the National Survey of Drug Use and Health restricted use data portal 2004-2013. Multilevel logistic regression of individual-level data was used to test differences between MML and non-MML states and changes in prevalence of past-month marijuana use and perceived availability from before to after passage of MML among adolescents, young adults and older adults controlling for demographics., Results: Among adults 26+, past-month prevalence of marijuana use increased from 5.87% to 7.15% after MML passage (Adjusted Odds Ratio (AOR): 1.24 [1.16-1.31]), but no change in prevalence of use was found for 12-17 or 18-25 year-olds. Perceived availability of marijuana increased after MML was enacted among those 26+ but not in younger groups. Among all age groups, prevalence of marijuana use and perception of it being easily available was higher in states that would eventually pass MML by 2013 compared to those that had not. Perceived availability was significantly associated with increased risk of past-month marijuana use in all age groups., Conclusion: Evidence suggests perceived availability as a driver of change in use of marijuana due to MML. To date, this has only occurred in adults 26+ and different scenarios that could explain this change need to be further explored., Competing Interests: The authors have no conflict of interest to declare., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: There are knowledge gaps regarding the effectiveness of different approaches designed to prevent and deter driving under the influence of cannabis (DUIC). Policymakers are increasingly interested in evidence-based responses to DUIC as numerous jurisdictions worldwide have legally regulated cannabis or are debating such regulation. We contribute a comprehensive review of international literature on countermeasures that address DUIC, and identify where and how such measures have been evaluated., Methods: The following databases were systematically searched from 1995 to present: Medline, Embase, PsycINFO, CINAHL, Sociological Abstracts, and Criminal Justice Abstracts. Hand searching of relevant documents, internet searches for grey literature, and review of ongoing email alerts were conducted to capture any emerging literature and relevant trends., Results: Numerous international jurisdictions have introduced a variety of measures designed to deter DUIC. Much interest has been generated regarding non-zero per se laws that set fixed legal limits for tetrahydrocannabinol and/or its metabolites detected in drivers. Other approaches include behavioural impairment laws, zero-tolerance per se laws, roadside drug testing, graduated licensing system restrictions, and remedial programs. However, very few evaluations have appeared in the literature., Conclusions: Although some promising results have been reported (e.g., roadside testing), it is premature to draw firm conclusions regarding the broader impacts of general deterrent approaches to DUIC. This review points to the need for a long-term commitment to rigorously evaluate, using multiple methods, the impact of general and specific deterrent DUIC countermeasures., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: There is concern that medical marijuana laws (MMLs) could negatively affect adolescents. To better understand these policies, we assess how adolescent exposure to MMLs is related to educational attainment., Methods: Data from the 2000 Census and 2001-2014 American Community Surveys were restricted to individuals who were of high school age (14-18) between 1990 and 2012 (n=5,483,715). MML exposure was coded as: (i) a dichotomous "any MML" indicator, and (ii) number of years of high school age exposure. We used logistic regression to model whether MMLs affected: (a) completing high school by age 19; (b) beginning college, irrespective of completion; and (c) obtaining any degree after beginning college. A similar dataset based on the Youth Risk Behavior Survey (YRBS) was also constructed for confirmatory analyses assessing marijuana use., Results: MMLs were associated with a 0.40 percentage point increase in the probability of not earning a high school diploma or GED after completing the 12th grade (from 3.99% to 4.39%). High school MML exposure was also associated with a 1.84 and 0.85 percentage point increase in the probability of college non-enrollment and degree non-completion, respectively (from 31.12% to 32.96% and 45.30% to 46.15%, respectively). Years of MML exposure exhibited a consistent dose response relationship for all outcomes. MMLs were also associated with 0.85 percentage point increase in daily marijuana use among 12th graders (up from 1.26%)., Conclusions: Medical marijuana law exposure between age 14 to 18 likely has a delayed effect on use and education that persists over time., Competing Interests: No conflict declared., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: Medical marijuana legalization is associated with a higher prevalence of marijuana use which may affect cigarette use and nicotine dependence in co-users. In the present study, we examined relationships between statewide legalization of medical marijuana and prevalence of cigarette and marijuana co-use and nicotine dependence in co-using adolescents and adults., Methods: Data were analyzed from the 2013 National Survey on Drug Use and Health. We compared cigarette and marijuana co-use in the past 30days across age categories (12-64 years) by statewide medical marijuana legalization. Logistic regression models were used to estimate the odds of having nicotine dependence among current cigarette smokers who also reported past 30-day marijuana use and "ever but not current" marijuana use (vs. "never" use) adjusting for covariates including statewide legalization of medical marijuana., Results: Overall, 5.1% of the sample reported past 30-day cigarette and marijuana co-use and a higher proportion of co-users resided in states where medical marijuana was legal compared to illegal (5.8% vs. 4.8%; p=0.0011). Co-use was associated with greater odds of having nicotine dependence compared to cigarette-only use across age categories. Odds were highest and up to 3-times higher in adolescents aged 12-17 years (OR=3.54; 95%CI: 1.81-6.92) and adults aged 50-64 years (OR=3.08; CI: 1.45-6.55)., Conclusion: Marijuana policy could inadvertently affect cigarette and marijuana co-use and pose challenges to tobacco cessation., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: The average amount of marijuana in a joint is unknown, yet this figure is a critical quantity for creating credible measures of marijuana consumption. It is essential for projecting tax revenues post-legalization, estimating the size of illicit marijuana markets, and learning about how much marijuana users are consuming in order to understand health and behavioral consequences., Methods: Arrestee Drug Abuse Monitoring data collected between 2000 and 2010 contain relevant information on 10,628 marijuana transactions, joints and loose marijuana purchases, including the city in which the purchase occurred and the price paid for the marijuana. Using the Brown-Silverman drug pricing model to link marijuana price and weight, we are able to infer the distribution of grams of marijuana in a joint and provide a Bayesian posterior distribution for the mean weight of marijuana in a joint., Results: We estimate that the mean weight of marijuana in a joint is 0.32g (95% Bayesian posterior interval: 0.30-0.35)., Conclusions: Our estimate of the mean weight of marijuana in a joint is lower than figures commonly used to make estimates of marijuana consumption. These estimates can be incorporated into drug policy discussions to produce better understanding about illicit marijuana markets, the size of potential legalized marijuana markets, and health and behavior outcomes., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Aims: Media reports suggest increasing popularity of marijuana concentrates ("dabs"; "earwax"; "budder"; "shatter; "butane hash oil") that are typically vaporized and inhaled via a bong, vaporizer or electronic cigarette. However, data on the epidemiology of marijuana concentrate use remain limited. This study aims to explore Twitter data on marijuana concentrate use in the U.S. and identify differences across regions of the country with varying cannabis legalization policies., Methods: Tweets were collected between October 20 and December 20, 2014, using Twitter's streaming API. Twitter data filtering framework was available through the eDrugTrends platform. Raw and adjusted percentages of dabs-related tweets per state were calculated. A permutation test was used to examine differences in the adjusted percentages of dabs-related tweets among U.S. states with different cannabis legalization policies., Results: eDrugTrends collected a total of 125,255 tweets. Almost 22% (n=27,018) of these tweets contained identifiable state-level geolocation information. Dabs-related tweet volume for each state was adjusted using a general sample of tweets to account for different levels of overall tweeting activity for each state. Adjusted percentages of dabs-related tweets were highest in states that allowed recreational and/or medicinal cannabis use and lowest in states that have not passed medical cannabis use laws. The differences were statistically significant., Conclusions: Twitter data suggest greater popularity of dabs in the states that legalized recreational and/or medical use of cannabis. The study provides new information on the epidemiology of marijuana concentrate use and contributes to the emerging field of social media analysis for drug abuse research., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Background: The liberalization of marijuana laws has led to concerns that such changes will increase "drugged driving" and crash-related mortality. California decriminalized marijuana effective January 1, 2011; we examine the impact of this change on marijuana-involved driving., Methods: We used laboratory testing from roadside surveys and the Fatality Analysis Reporting System (FARS) to assess impacts on weekend nighttime drivers and fatally injured drivers, respectively. We calculated marijuana prevalence (measured by laboratory-confirmed delta-9-tetrahydrocannabinol [THC] in roadside surveys and cannabinoids in FARS) and compared corresponding 95% confidence intervals (CI) to identify statistically significant changes post-decriminalization. We also conducted multiple logistic regression analyses to determine whether the odds of marijuana-involved driving increased significantly after controlling for potential confounders., Results: There was no statistically significant change in the prevalence of THC-positive driving among weekend nighttime drivers (n=894) in 2012 (9.2%; 95% CI: 6.3, 12.2) compared to 2010 (11.3%; 95% CI: 8.5, 14.0) or in the adjusted odds of testing positive for THC (adjusted odds ratio [AOR]=0.96; 95% CI: 0.57, 1.60). In contrast, we found a statistically significant increase in the prevalence of cannabinoids among fatally injured drivers in 2012 (17.8%; 95% CI: 14.6, 20.9) compared to the pre-decriminalization period 2008-2010 (11.8%; 95% CI: 10.3, 13.3). The adjusted odds of testing positive for cannabinoids were also significantly higher in 2012 (AOR=1.67; 95% CI: 1.28, 2.18)., Conclusions: Our study generated discrepant findings regarding the impact of decriminalization on marijuana-involved driving in California. Factors that may have contributed to these findings, particularly methodological factors, are discussed., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

In this discussion of contributed papers for the special issue of DAD, the author draws attention to early American laws concerning cannabis and to statements made about the epidemiology of cannabis smoking and other drug use between 1858 and the contemporary scene, with coverage of opium, heroin, tobacco, alcohol, cocaine, kava, and other drugs. He discusses these steppingstone and gateway processes in relation to political environment and in relation to scientific challenges such as uncontrolled confounding. He provides a critique of between-individual research designs, including co-twin and co-sib designs of behavior genetics, as well as imaging research, where uncontrolled confounding often exists. He highlights the epidemiologic case-crossover design and prevention research experiments as potentially valuable approaches in new directions for research on the steppingstone and gateway processes., (Copyright © 2012. Published by Elsevier Ireland Ltd.)

The use of smoked marijuana as a therapeutic agent is presently a matter of considerable debate in the United States. Many people suffering from a variety of disorders maintain that it is necessary for their adequate treatment. Yet, the evidence to support claims is insufficient for FDA approval. An interim solution is proposed which would allow patients referred by their physicians to participate in a 6-month program of legal marijuana availability, similar to the 'compassionate IND' program of a number of years ago. A technique similar to that used for post-marketing surveillance is proposed for obtaining quantitative data for a limited number of potential indications. These are: (1) nausea and vomiting associated with cancer chemotherapy or other causes, (2) weight loss associated with debilitating illnesses, (3) spasticity secondary to neurological diseases, and (4) chronic pain syndromes.