The effects of price and policy on marijuana use: what can be learned from the Australian experience?

Health, safety, and socioeconomic impacts of cannabis liberalization laws: An evidence and gap map

Background

Globally, cannabis laws and regulations are rapidly changing. Countries are increasingly permitting access to cannabis under various decriminalization, medicalization, and legalization laws. With strong economic, public health, and social justice incentives driving these domestic cannabis policy reforms, liberalization trends are bound to continue. However, despite a large and growing body of interdisciplinary research addressing the policy-relevant health, safety, and socioeconomic consequences of cannabis liberalization, there is a lack of robust primary and systematic research that comprehensively investigates the consequences of these reforms.

Objectives

This evidence and gap map (EGM) summarizes the empirical evidence on cannabis liberalization policies. Primary objectives were to develop a conceptual framework linking cannabis liberalization policies to relevant outcomes, descriptively summarize the empirical evidence, and identify areas of evidence concentration and gaps.

Search Methods

We comprehensively searched for eligible English-language empirical studies published across 23 academic databases and 11 gray literature sources through August 2020. Additions to the pool of potentially eligible studies from supplemental sources were made through November 2020.

Selection Criteria

The conceptual framework for this EGM draws upon a legal epidemiological perspective highlighting the causal effects of law and policy on population-level outcomes. Eligible interventions include policies that create or expand access to a legal or decriminalized supply of cannabis: comprehensive medical cannabis laws (MCLs), limited medical cannabidiol laws (CBDLs), recreational cannabis laws (RCLs), industrial hemp laws (IHLs), and decriminalization of cultivations laws (DCLs). Eligible outcomes include intermediate responses (i.e., attitudes/behaviors and markets/environments) and longer-term consequences (health, safety, and socioeconomic outcomes) of these laws.

Data Collection and Analysis

Both dual screening and dual data extraction were performed with third person deconfliction. Primary studies were appraised using the Maryland Scientific Methods Scale and systematic reviews were assessed using AMSTAR 2.

Main Results

The EGM includes 447 studies, comprising 438 primary studies and nine systematic reviews. Most research derives from the United States, with little research from other countries. By far, most cannabis liberalization research focuses on the effects of MCLs and RCLs. Studies targeting other laws-including CBDLs, IHLs, and DCLs-are relatively rare. Of the 113 distinct outcomes we documented, cannabis use was the single most frequently investigated. More than half these outcomes were addressed by three or fewer studies, highlighting substantial evidence gaps in the literature. The systematic evidence base is relatively small, comprising just seven completed reviews on cannabis use (3), opioid-related harms (3), and alcohol-related outcomes (1). Moreover, we have limited confidence in the reviews, as five were appraised as minimal quality and two as low quality.

Authors’ Conclusions

More primary and systematic research is needed to better understand the effects of cannabis liberalization laws on longer-term-and arguably more salient-health, safety, and socioeconomic outcomes. Since most research concerns MCLs and RCLs, there is a critical need for research on the societal impacts of industrial hemp production, medical CBD products, and decriminalized cannabis cultivation. Future research should also prioritize understanding the heterogeneous effects of these laws given differences in specific provisions and implementation across jurisdictions.

Delta-8 tetrahydrocannabinol: a scoping review and commentary

BACKGROUND AND AIMS

Delta-8 tetrahydrocannabinol (THC) is a psychoactive substance from the Cannabis plant that has been rising in popularity in the United States since the 2018 US Farm Bill implicitly legalized it. This study reviewed research from peer-reviewed and non-peer-reviewed (e.g. anecdotal and news) reports related to delta-8 THC to summarize current knowledge and implications for public health and safety.

METHODS

A scoping review was conducted using PubMed, Scopus, Google Scholar and Google as search engines, leading to the identification of 103 documents that were summarized. The themes that emerged were (1) legality, (2) use (popularity, motives, psychoactivity/potency, benefits/consequences), (3) synthesis (byproducts, laboratory testing) and (4) retail (availability, price, packaging, youth-oriented marketing). A second author independently coded 20% of the documents, which verified the categorization of articles by these emergent themes.

RESULTS

Most research used animal/cell models or focused upon ways to identify the chemical structure of delta-8 THC in various products. Findings suggest that people often use delta-8 THC as a substitute for other substances. Anecdotally, delta-8 THC is a less potent psychoactive than delta-9 THC; however, several negative consequences have been reported. There is no federal age restriction for purchase/possession of delta-8 THC products. Delta-8 THC is readily accessible on-line, is typically less expensive than delta-9 THC and is often marketed in ways that would seemingly appeal to children. There are no regulations on synthesis, resulting in products being contaminated and/or yielding inconsistent effects. There have been thousands of calls to US poison control centers due to accidental delta-8 THC exposure among minors.

CONCLUSIONS

Most research on delta-8 THC is largely anecdotal, not peer-reviewed and does not involve human subjects. Future research should examine delta-8 THC use using nationally representative samples to more clearly understand the prevalence and consequences of use. Laws are needed to mitigate the risks of using delta-8 THC, particularly quality control of synthesis and minimum purchase age.

U.S. State approaches to cannabis licensing

U.S. states have taken varied approaches to licensing cannabis businesses under federal prohibition, but up to now there is limited research on cross-state licensing approaches. This paper provides a systematic analysis of the current licensing strategies taken by all states that have passed medical cannabis laws (MCLs)/recreational cannabis laws (RCLs). We construct comprehensive data on cannabis business licenses offered in each state, as well as metrics for license categories, cost, and issuance volume. We then analyze patterns between these metrics, also considering how long ago states implemented MCLs/RCLs, qualitative licensing aspects, state ideology and voting preference, and state cannabis taxation data. We observe that states tend to license medical cannabis more restrictively than adult-use cannabis: i.e., by offering licenses in fewer categories, at higher cost, in lower issuance volume, and more often mandating vertical integration. Additionally, states that implemented MCLs/RCLs earlier tend to offer licenses in more categories, at lower cost, and in greater volumes. Further, though states that implemented MCLs recently lean conservative and Republican, we do not observe clear relationships between ideology or voting preference and licensing policy. In our supporting results, we observe that a greater share of states with complex licensing structures impose non-retail price cannabis taxes than states overall, and we discuss how states have changed their licensing policies over time.

Do alcohol and cannabis substitute or complement each other? Analysis from behavioral economics for formulating public policy on substance use in Colombia

After alcohol and tobacco, cannabis is the third most used substance among young Colombian adults, and many consume alcohol and cannabis concomitantly. However, academics have debated whether these substances substitute or complement each other among consumers. Understanding the relationship between the price and demand for psychoactive substances can clarify consumption patterns and help to develop strategies to reduce harmful consumption. This paper summarizes worldwide evidence of both complementary and substitution relationships and discusses the most probable relationship types in Colombia based on its substance use patterns and current regulations. Like other countries, Colombia is considering legalizing recreational cannabis use. However, there is a growing concern that legalization would increase the negative impacts of cannabis and increase alcohol use among the young adult population. The lack of Colombian empirical studies about the impacts of legal changes on the cannabis market makes it difficult to predict how such changes would affect demand and price elasticities.

Characteristics that influence purchase choice for cannabis products: a systematic review

Introduction

When non-medical cannabis use became legal, government regulators implemented policies to encourage safer consumption through access to a regulated market. While this market is growing, sales still occur through unregulated channels. This systematic review identifies factors influencing cannabis purchasing to help policymakers understand why consumers still purchase illicit market cannabis (registered with PROSPERO CRD42020176079).

Methods

A comprehensive search strategy included databases in health, business, and social science fields (inception to June 2020). Studies were eligible for inclusion if they were conducted with persons who purchase cannabis and examine at least one attribute that would influence purchase choice and were published in the English language. Studies could be of any methodological design. Two independent reviewers completed two levels of screening, and all extraction was verified by a second reviewer. A qualitative synthesis of the findings was completed. The quality of the included studies was assessed using the Mixed Methods Appraisal Tool.

Results

Of the 4839 citations screened, 96 were eligible for full-text review and 35 were included in the final synthesis. Aspects of price were the most common factors (27 studies). Twenty studies measured price elasticity; most studies found that demand was price inelastic. Many other attributes were identified (e.g., product quality, route of administration, product recommendations, packaging), but none were explored in depth. Eleven studies addressed aspects of product quality including demand elasticity based on quality, potency, and aroma. Studies also explored consumer-perceived “quality” but provided no definition; differences in quality appeared to impact consumer choice. Smoking cannabis appeared to be the preferred route of administration but was only examined in three studies. There was insufficient data to understand in the impact of other attributes on choice. There appeared to be preference heterogeneity for different attributes based on the consumer’s experience, reason for use, and gender.

Conclusion

While price influences choices, demand is relatively inelastic. This suggests that consumers may be seeking lowest-cost, unregulated cannabis to avoid reducing consumption. Beyond price, there is a significant gap in our understanding of consumer choices. Perceived quality does appear to impact choice; however, more research is needed due to the lack of a recognized definition for cannabis quality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42238-022-00117-0.

Who would try (or use more) cannabis if it were legal?

INTRODUCTION

This study sought to determine: (i) whether decriminalisation of cannabis use would increase the proportion who would try the drug; and (ii) the proportion who would use more cannabis; and (iii) explore their characteristics.

METHODS

Australian National Drug Strategy Household surveys were used to address (i)-(iii). Significant independent predictors of (i) and (ii) were identified using logistic regression.

RESULTS

An estimated 4.2% of the population aged 14 and over (n = 882 708) who have never tried cannabis before would try it, if use of the drug were made legal, while 2.6% of the population aged 14 and over (537 000) would use more cannabis if its use were made legal. Respondents were more likely to say they would try cannabis if they were male, younger or suffered from a mild, moderate and/or severe level of psychological stress. Respondents were more likely to say they would use more cannabis if they were male, younger, psychologically stressed and not currently frequent users of the drug.

DISCUSSION AND CONCLUSIONS

Decriminalisation of cannabis use is likely to result in an increase in consumption of the drug among young people with mental health problems. If cannabis use is decriminalised, Australian State and Territory Governments should make provision for a possible increase in demand for drug treatment and for public education on the risks associated with frequent/prolonged cannabis use.

Does correctional supervision of amphetamine users reduce the risk of re-offending?

AIM

To examine the specific deterrent effect of offender supervision on the risk of a further offence by persons convicted of amphetamine use and/or possession.

DESIGN

Observational study of two groups matched on a wide range of factors using augmented inverse probability of treatment weighting.

SETTING

New South Wales (NSW), Australia.

PARTICIPANTS

A total of 2099 persons convicted of amphetamine use and/or possession and placed on either a supervised good behaviour bond (1004) or a bond without supervision (1096).

MEASUREMENTS

Conviction for another amphetamine use/possession offence, any drug offence, assault or theft within 48 months free time after the index court appearance.

FINDINGS

Only two of the treatment estimates were consistent with a deterrent effect. Where the outcome was an assault offence, the estimated reduction in risk of re-offending was 1%. Where the outcome was a theft offence, the estimated reduction in the risk of reoffending was 0.07%. Neither result was statistically significant. The coefficients measuring the effect of supervision on the remaining two outcomes (use/possess amphetamine and use/possess any drug) were both positive and not statistically significant.

CONCLUSION

Correctional supervision does not appear to have been effective in New South Wales, Australia, in reducing the risk of reoffending among people convicted of amphetamine use/possession.

'We realised we needed a new approach': Government and law enforcement perspectives on the implementation and future of the drug decriminalisation policy in vietnam

In 2009, Vietnam officially decriminalised drug use through amendments to the criminal law. The amendments outlined explicitly that illicit drug use would be seen as an administrative violation, but not a criminal offence. This legal transition has not been without implementation challenges, and police particularly have struggled to find a balance between drug law enforcement and decriminalisation. Despite being a health-orientated drug policy amendment, in practice it allows police to send suspected drug users to compulsory treatment centres without judicial oversight and people who use drugs continue to face challenges in their interface with law enforcement which can negatively impact access to harm reduction and community-based treatment programs. Using policy desk research combined with indepth interviews with 14 key informants from people representing a range of relevant Vietnamese government (n = 10) and non-government agencies (n = 4), this paper explores some insights and considerations into how decriminalisation of drug use in the amended law was implemented. We explore key informant perspectives into how the decriminalisation amendment could be implemented more effectively in order to improve health outcomes for people who use drugs in Vietnam through re-envisioned police protocols and practices. Findings show that while decriminalising drug use in Vietnam was designed as a progressive and health-orientated drug policy, the ongoing disconnect between the health intent of the policy and the police-led oversight of its implementation in the community persists. Part of this disconnect is explained by the lack of training and clear protocols that would enhance the police in their ability to contribute to the health intent of the policy rather than continue to view drug use through a drug law enforcement only lens. The paper calls for further collaboration across policing and the health and community-based organisations delivering services for people who use drugs. We suggest that through developing a deeper understanding of the interplay between policing and the implementation of harm reduction policy and programs, decriminalisation can co-exist within a broader and deeply entrenched drug control strategy in Vietnam.

Does liberalisation of cannabis policy influence levels of use in adolescents and young adults? A systematic review and meta-analysis

OBJECTIVES

To examine the effect of cannabis policy liberalisation (decriminalisation and legalisation) levels of use in adolescents and young adults.

DESIGN

Systematic review and meta-analysis.

INCLUSION CRITERIA

Included studies were conducted among individuals younger than 25 years and quantitatively assessing consequences of cannabis policy change. We excluded articles: (A) exclusively based on participants older than 25 years; (B) only reporting changes in perceptions of cannabis use; (C) not including at least two measures of cannabis use; (D) not including quantitative data; and (E) reviews, letters, opinions and policy papers. PubMed, PsycINFO, Embase and Web of Science were searched through 1 March 2018.

DATA EXTRACTION AND SYNTHESIS

Two independent readers reviewed the eligibility of titles and abstracts and read eligible articles, and four authors assessed the risk of bias (Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies). Extracted data were meta-analysed. The protocol was registered with PROSPERO.

RESULTS

3438 records were identified via search terms and four via citation lists; 2312 were retained after removal of duplicates, 99 were assessed for eligibility and 41 were included in our systematic review. 13 articles examined cannabis decriminalisation, 20 examined legalisation for medical purposes and 8 examined legalisation for recreational purposes. Findings regarding the consequences of cannabis decriminalisation or legalisation for medical purposes were too heterogeneous to be meta-analysed. Our systematic review and meta-analysis suggest a small increase in cannabis use among adolescents and young adults following legalisation of cannabis for recreational purposes (standardised mean difference of 0.03, 95% CI -0.01 to -0.07). Nevertheless, studies characterised by a very low/low risk of bias showed no evidence of changes in cannabis use following policy modifications.

CONCLUSIONS

Cannabis policy liberalisation does not appear to result in significant changes in youths' use, with the possible exception of legalisation for recreational purposes that requires monitoring.

TRIAL REGISTRATION NUMBER

CRD42018083950.

Cannabis decriminalization: A study of recent policy change in five U.S. states

BACKGROUND

A number of public health professional organizations support the decriminalization of cannabis due to adverse effects of cannabis-related arrests and legal consequences, particularly on youth. We sought to examine the associations between cannabis decriminalization and both arrests and youth cannabis use in five states that passed decriminalization measures between the years 2008 and 2014: Massachusetts (decriminalized in 2008), Connecticut (2011), Rhode Island (2013), Vermont (2013), and Maryland (2014).

METHODS

Data on cannabis possession arrests were obtained from federal crime statistics; data on cannabis use were obtained from state Youth Risk Behavior Survey (YRBS) surveys, years 2007-2015. Using a "difference in difference" regression framework, we contrasted trends in decriminalization states with those from states that did not adopt major policy changes during the observation period.

RESULTS

Decriminalization was associated with a 75% reduction in the rate of drug-related arrests for youth (95% CI: 44%, 89%) with similar effects observed for adult arrests. Decriminalization was not associated with any increase in the past-30 day prevalence of cannabis use overall (relative change=-0.2%; 95% CI: -4.5%, 4.3%) or in any of the individual decriminalization states.

CONCLUSIONS

Decriminalization of cannabis in Massachusetts, Connecticut, Rhode Island, Vermont, and Maryland resulted in large decreases in cannabis possession arrests for both youth and adults, suggesting that the policy change had its intended consequence. Our analysis did not find any increase in the prevalence of youth cannabis use during the observation period.

Big data on a big new market: Insights from Washington State's legal cannabis market

INTRODUCTION

Voters in eight U.S. states have passed initiatives to legalize large-scale commercial production of cannabis for non-medical use. All plan or require some form of "seed-to-sale" tracking systems, which provide a view of cannabis market activity at a heretofore unimagined level of detail. Legal markets also create a range of new matters for policy makers to address.

DATA

Publicly available data were obtained on approximately 45 million individually priced items purchased in the 35 million retail transactions that took place during the first two and a half years of Washington State's legal cannabis market. Records include product type (flower, extract, lotion, liquid edible, etc.), product name, price, and potency with respect to multiple cannabinoids, notably THC and CBD. Items sold can be traced back up the supply chain through the store to the processor and producer, to the level of identifying the specific production batch and mother plant, the firm that tested the product, and test results.

METHOD

Data visualization methods are employed to describe spatial-temporal patterns of multiple correlated attributes (e.g., price and potency) broken down by product. Text-analytic methods are used to subdivide the broad category of "extracts for inhalation" into more homogeneous sub-categories. To understand the competitiveness of the legal cannabis market in Washington we calculate the Herfindahl-Hirschman index (HHI) for processors and retailers.

RESULTS

Cannabis prices fell steadily and proportionally at the processor and retailer levels. Retail and wholesale price maintained a roughly 3:1 ratio for multiple product types after some initial fluctuations. Although a wide range of edibles are sold, they account for a modest share of consumer spending; extracts for inhalation are a larger and heterogeneous market segment. The HHI indicates the cannabis market is highly competitive at the processor level, but less so for retail markets at the county level.

CONCLUSIONS

Washington's state-legal cannabis market is diverse and rapidly evolving in terms of pricing, products, and organization. Post-legalization, researchers and policy makers may need to think in terms of a family of cannabis products, akin to how we think of new psychoactive substances and amphetamine-type stimulants, not a single drug "cannabis."

Early Impacts of Marijuana Legalization: An Evaluation of Prices in Colorado and Washington

Following the legalization and regulation of marijuana for recreational purposes in states with medical markets, policymakers and researchers seek empirical evidence on how, and how fast, supply and demand changed over time. Prices are an indication of how suppliers and consumers respond to policy changes, so this study uses a difference-in-difference approach to exploit the timing of policy implementation and identify the impacts on marijuana prices 4-5 months after markets opened. This study uses unique longitudinal survey data of prices paid by consumers and a web-scraped dataset of dispensary prices advertised online for three U.S. medical marijuana states that all eventually legalized recreational marijuana. Results indicate there were no impacts on the prices paid for medical or recreational marijuana by state-representative residents within the short 4- to 5-months window following legalization. However, there were differences in how much people paid if they obtained marijuana for recreational purposes from a recreational store. Further analysis of advertised prices confirms this result, but further demonstrates heterogeneous responses in prices across types of commonly advertised strains; prices either did not change or increased depending on the strain type. A key implication of our findings is that there are both supply and demand responses at work in the opening of legalized markets, suggesting that evaluations of immediate effects may not accurately reflect the long run impact of legalization on consumption.

Police crackdowns, structural violence and impact on the well-being of street cannabis users in a Nigerian city

BACKGROUND

There is abundant literature on the impact of law enforcement on cannabis markets, but scant literature on the effects of law enforcement on cannabis users. This study undertook a qualitative exploration of police crackdowns as a form of structural violence and examined their impact on the well-being of street cannabis users in a Nigerian city.

METHODS

The study was qualitative and descriptive. It was carried out in Uyo, southern Nigeria. Ninety-seven (97) frequent cannabis users (78 males and 19 females) took part. They were aged between 21 and 34 years and recruited from 11 cannabis hot-points in the city. Data were collected through in-depth, individual interviews, conducted over six-months. Data analysis was thematic and data-driven, involving identifying themes, assigning codes, revising codes and verification by independent qualitative methodology experts.

RESULTS

Police crackdowns are commonly experienced by street cannabis users. These do not reduce cannabis use, but displace cannabis markets. Crackdowns are associated with police brutality, confiscation of funds, drugs and belongings, stigma and discrimination, arrest and incarceration, which impacts negatively on the health, livelihoods and well-being of cannabis users. Cannabis users try to escape arrest by running from police, disposing of cannabis, disguising themselves and, when caught, bribing officers to secure release.

CONCLUSION

Crackdowns constitute a form of structural violence in the everyday life of cannabis users, and have negative effects on their health and social and economic well-being. Cannabis use should be decriminalized de facto and arrested users directed to treatment and skills training programmes. Treatment and social services for users should be expanded and legal aid interventions should be mounted to support users in addressing discriminatory practices and human rights violations.

Misreporting and econometric modelling of zeros in survey data on social bads: An application to cannabis consumption

When modelling "social bads," such as illegal drug consumption, researchers are often faced with a dependent variable characterised by a large number of zero observations. Building on the recent literature on hurdle and double-hurdle models, we propose a double-inflated modelling framework, where the zero observations are allowed to come from the following: nonparticipants; participant misreporters (who have larger loss functions associated with a truthful response); and infrequent consumers. Due to our empirical application, the model is derived for the case of an ordered discrete-dependent variable. However, it is similarly possible to augment other such zero-inflated models (e.g., zero-inflated count models, and double-hurdle models for continuous variables). The model is then applied to a consumer choice problem of cannabis consumption. We estimate that 17% of the reported zeros in the cannabis survey are from individuals who misreport their participation, 11% from infrequent users, and only 72% from true nonparticipants.

The stigmatisation of 'ice' and under-reporting of meth/amphetamine use in general population surveys: A case study from Australia

BACKGROUND AND AIMS

Stigmatisation of illicit drug use is known to discourage people from reporting their use of illicit drugs. In the context of Australia's two recent "ice-epidemics" this study examines whether rapid increases in community concern about meth/amphetamine concurrent with increased stigmatising media reporting about meth/amphetamine "epidemics" are associated with increased under-reporting of its use in population surveys.

METHODS

We examined the relationship between general population trends in self-reported lifetime use of and attitudes towards meth/amphetamine between 2001 and 2013, contextualised against related stimulants and heroin, using five waves of Australia's National Drug Strategy Household Survey (NDSHS), alongside trends in print media reporting on meth/amphetamine from 2001 to 2014.

RESULTS

Analysis of NDSHS data showed significant increases in community concern about meth/amphetamine between 2004 and 2007, and 2010 and 2013 in all birth cohorts and age groups. In both periods self-reported lifetime use of meth/amphetamine fell in many birth cohorts. The falls were only statistically significant in the first period, for birth cohorts from 1961-1963 to 1973-1975. Falls in lifetime use within a cohort from one period to the next are incongruous and we did not observe them in the other drugs considered. Equally, increases in concern were specific to meth/amphetamine. We counted substantial and rapid increase in the number of newspaper reports about meth/amphetamine in both periods, particularly reports including the term 'epidemic'.

CONCLUSIONS

Rapid increases in the quantum of media reporting stigmatising a drug (through its construction as an 'epidemic') accompanying increased general public concerns about the drug may increase the tendency to under-report lifetime use. This may make it difficult to rely upon household surveys to observe trends in patterns of use and suggests that policy makers, media and others in the AOD sector should avoid stigmatisation of drugs, particularly during periods of heightened concern.

Cannabis Liberalization and Adolescent Cannabis Use: A Cross-National Study in 38 Countries

AIMS

To assess the associations between types of cannabis control policies at country level and prevalence of adolescent cannabis use.

SETTING, PARTICIPANTS AND DESIGN

Multilevel logistic regressions were performed on 172,894 adolescents 15 year of age who participated in the 2001/2002, 2005/2006, or 2009/2010 cross-sectional Health Behaviour in School-Aged Children (HBSC) survey in 38 European and North American countries.

MEASURES

Self-reported cannabis use status was classified into ever use in life time, use in past year, and regular use. Country-level cannabis control policies were categorized into a dichotomous measure (whether or not liberalized) as well as 4 detailed types (full prohibition, depenalization, decriminalization, and partial prohibition). Control variables included individual-level sociodemographic characteristics and country-level economic characteristics.

FINDINGS

Considerable intra-class correlations (.15-.19) were found at country level. With respect to the dichotomized cannabis control policy, adolescents were more likely to ever use cannabis (odds ratio (OR) = 1.10, p = .001), use in past year (OR = 1.09, p = .007), and use regularly (OR = 1.26, p = .004). Although boys were substantially more likely to use cannabis, the correlation between cannabis liberalization and cannabis use was smaller in boys than in girls. With respect to detailed types of policies, depenalization was associated with higher odds of past-year use (OR = 1.14, p = .013) and regular use (OR = 1.23, p = .038), and partial prohibition was associated with higher odds of regular use (OR = 2.39, p = .016). The correlation between cannabis liberalization and regular use was only significant after the policy had been introduced for more than 5 years.

CONCLUSIONS

Cannabis liberalization with depenalization and partial prohibition policies was associated with higher levels of regular cannabis use among adolescents. The correlations were heterogeneous between genders and between short- and long-terms.

Assessing the public health impacts of legalizing recreational cannabis use in the USA

A major challenge in assessing the public health impact of legalizing cannabis use in Colorado and Washington State is the absence of any experience with legal cannabis markets. The Netherlands created a de facto legalized cannabis market for recreational use, but policy analysts disagree about how it has affected rates of cannabis use. Some US states have created de facto legal supply of cannabis for medical use. So far this policy does not appear to have increased cannabis use or cannabis-related harm. Given experience with more liberal alcohol policies, the legalization of recreational cannabis use is likely to increase use among current users. It is also likely that legalization will increase the number of new users among young adults but it remains uncertain how many may be recruited, within what time frame, among which groups within the population, and how many of these new users will become regular users.

Does liberalizing cannabis laws increase cannabis use?

A key question in the ongoing policy debate over cannabis' legal status is whether liberalizing cannabis laws leads to an increase in cannabis use. This paper provides new evidence on the impact of a specific type of liberalization, decriminalization, on initiation into cannabis use. Our identification strategy exploits variation in the timing of cannabis policy reforms and our estimation framework marries a difference-in-difference approach with a discrete time duration model. Our results reveal evidence of both heterogeneity and dynamics in the response of cannabis uptake to decriminalization. Overall, we find that the impact of decriminalization is concentrated amongst minors, who have a higher rate of uptake in the first five years following its introduction.

Cost benefit analysis of two policy options for cannabis: status quo and legalisation

Aims

To date there has been limited analysis of the economic costs and benefits associated with cannabis legalisation. This study redresses this gap. A cost benefit analysis of two cannabis policy options the status quo (where cannabis use is illegal) and a legalised–regulated option was conducted.

Method

A cost benefit analysis was used to value the costs and benefits of the two policies in monetary terms. Costs and benefits of each policy option were classified into five categories (direct intervention costs, costs or cost savings to other agencies, benefits or lost benefits to the individual or the family, other impacts on third parties, and adverse or spill over events). The results are expressed as a net social benefit (NSB).

Findings

The mean NSB per annum from Monte Carlo simulations (with the 5 and 95 percentiles) for the status quo was $294.6 million AUD ($201.1 to $392.7 million) not substantially different from the $234.2 million AUD ($136.4 to $331.1 million) for the legalised–regulated model which excludes government revenue as a benefit. When government revenue is included, the NSB for legalised–regulated is higher than for status quo. Sensitivity analyses demonstrate the significant impact of educational attainment and wellbeing as drivers for the NSB result.

Conclusion

Examining the percentiles around the two policy options, there appears to be no difference between the NSB for these two policy options. Economic analyses are essential for good public policy, providing information about the extent to which one policy is substantially economically favourable over another. In cannabis policy, for these two options this does not appear to be the case.

Can price get the monkey off our back? A meta-analysis of illicit drug demand

Because of the increased availability of price data over the past 15 years, several studies have estimated the demand for illicit drugs, providing 462 estimates of the price elasticity. Results from estimating several meta-regressions reveal that these price elasticity estimates are influenced by a number of study characteristics. For instance, the price elasticity differs across drugs, with its absolute value being smallest for marijuana, compared with cocaine and heroin. Furthermore, price elasticity estimates are sensitive to whether demand is modeled in the short-run or the long-run, measures of quantity and price, whether or not alcohol and other illicit drugs are included in the specification of demand, and the location of demand. However, a number of other factors, including the functional form of demand, several specification issues, the type of data and method used to estimate demand, and the quality of the publication outlet, have less influence on the price elasticity.

Why Changes in Price Matter When Thinking About Marijuana Policy: A Review of the Literature on the Elasticity of Demand

Recent debates regarding liberalization of marijuana policies often rest on assumptions regarding the extent to which such policy changes would lead to a change in marijuana consumption and by whom. This paper reviews the economics literature assessing the responsiveness of consumption to changes in price and enforcement risk and explicitly considers how this responsiveness varies by different user groups. In doing so, it demonstrates how most of the research has examined responsiveness to prevalence of use, which is a composite of different user groups, rather than level of consumption among regular or heavy users, which represent the largest share of total quantities consumed. Thus, it is not possible to generate reliable estimates of the impact of liberalizing policies on either tax revenues or harms, as these outcomes are most directly influenced by the amounts consumed by regular or heavy users, not prevalence rates.

Individual and country-level effects of cannabis-related perceptions on cannabis use. A multilevel study among adolescents in 32 European countries

PURPOSE

The present article investigated individual and aggregated effects of cannabis-related perceptions and other cannabis-related indicators on 12-month cannabis use prevalence and frequency among 15-16 year olds using multilevel analysis across 32 European countries.

METHODS

Data on cannabis use, perceptions of availability, risks and friends' use as well as socio-demographic characteristics were taken from the 2007 European School Survey Project on Alcohol and Other Drugs. At the country level, aggregated measures of the perceptions were used. Data on cannabis price and 12-month cannabis use prevalence in the total population were taken from the World Drug Report. The analytical sample comprised 86,107 students (82.5% of the overall 2007 international database).

RESULTS

Strong and persistent individual-level effects were identified for perceived availability, perceived harm, and the number of cannabis using friends. The effects on cannabis use prevalence and frequency were more pronounced than country-level effects. At the country level, aggregated perceived peer consumption and population prevalence were significant predictors, whereas price was not found to be related to both outcome variables. The association between perceived friends' use and cannabis use was moderated by aggregated perceived availability.

CONCLUSIONS

Proximal influences related to the immediate social situation seem to be more strongly associated with cannabis use than do distal influences related to social contexts, emphasizing the importance of personal attitudes and perceptions in substance use behavior. Prevention programs may focus on informing adolescents about the potential risks of cannabis and on correcting misperceptions of social norms. Policy measures may target on reducing visibility of drug use.

Marijuana Price Gradients

California nearly legalized commercial marijuana production in 2010; in coming years, other states and California are expected to entertain similar proposals. This raises the question of whether marijuana diverted from legal production could displace current sources of marijuana in other states. Combining prior estimates of legal production cost with new estimates of the cost of smuggling within the United States suggests that in most states, diverted legal production would substantially undercut current prices. So, if one state legalized, then (illegal) interstate “exports” could depress marijuana prices throughout the United States, even if taxes are collected before diversion and export. The authors proxy smuggling costs by the current gradient in prices observed for Mexican or commercial-grade marijuana; based on seven different data sets, it appears to be roughly US$325 to US$475 per pound per 1,000 miles as one moves north from the Mexican border.

What economics can contribute to the addiction sciences

AIMS

The addiction sciences are intrinsically multi-disciplinary, and economics is among the disciplines that offer useful perspectives on the complex behaviors surrounding substance abuse. This paper summarizes contributions economics has made in the past and could make in the future towards understanding how illegal markets operate, how prices affect use, how use generates various consequences, and how policy shapes all three.

METHODS

Review of literature, concentrating on illegal drugs as insights concerning markets are particularly salient, although we also mention relevant studies from the alcohol and tobacco fields.

FINDINGS AND CONCLUSIONS

Economics offers tools and topical expertise that usefully complement other disciplines associated traditionally with the addiction sciences. Its value goes far beyond the ability to monetize non-monetary outcomes or to calculate a cost-benefit ratio.

The challenges in developing a rational cannabis policy

PURPOSE OF REVIEW

A rational cannabis policy would arguably be one that minimized the harms of both cannabis use and the legal policies adopted to control its use. We, therefore, review recent epidemiological evidence on the harmful effects of cannabis use and social research on the costs and benefits of cannabis prohibition.

RECENT FINDINGS

Epidemiological evidence suggests that cannabis increases the risk of road crash injury if users drive while intoxicated. When used chronically, cannabis can produce dependence, respiratory disease and psychotic symptoms, especially in vulnerable young adults. It probably also increases poor educational outcomes and possibly increases the use of other illicit drugs, although it is debated whether these relationships are causal. Proponents of a relaxation of cannabis prohibition argue that prohibition has failed to deter cannabis use, incurs substantial economic costs, has generated a large black market, has increased the potency of cannabis and users' access to other drugs and involves foregone tax revenue from the legal sale of cannabis.

SUMMARY

Development of a more rational cannabis policy requires better evaluations of both the health consequences of regular cannabis use and of the costs and benefits of enforcing the existing prohibition on its use. It also requires the liberalization of the international control system to allow member states to experiment with different methods of regulating and controlling cannabis use.

Neighborhood and individual factors in marijuana and other illicit drug use in a sample of low-income women

Few studies have systematically evaluated whether contextual variables differ in their ability to explain the use of different drugs in the same sample. Our objective was to examine correlates of use for different illicit drugs at the individual and neighborhood level in a tri-ethnic sample of low-income women, an underrepresented sample in drug research. Women 18-31 were recruited from a low-cost family planning clinic in southeast Texas from December 2001 to May 2003. Neighborhood level indicators of disadvantage, family structure, and nativity status from U.S. Census 2000 were linked with individual survey data. Multilevel logistic regression was used to examine the effect of individual and neighborhood level measures on lifetime use of marijuana only and of other illicit drugs in 594 women. Only individual level variables (younger age, non-Hispanic White ethnicity, not being married, greater peer acceptance of substance use) increased odds of exclusive marijuana use, controlling for neighborhood level factors. However, both neighborhood and individual level variables significantly predicted other illicit drug use. Residence in less disadvantaged neighborhoods, non-Hispanic White ethnicity, higher levels of education, greater acceptance of substance use by peers, and a larger number of perceived neighborhood problems increased odds of illicit drug use. Use of other illicit drugs with or without marijuana may be more closely tied to area level factors whereas factors driving exclusive marijuana use may not rely on localized structures to the same extent. Thus, community-level interventions may need to customize their approaches according to the type of drug use targeted. The implication of using neighborhood level variables in substance use research is also discussed.

Cannabis prices and dynamics of cannabis use

This paper uses duration models and self-reported cannabis histories from young Australians to study the dynamics of cannabis use. We find that low cannabis prices are associated with early initiation into cannabis use. While the decision to quit does not appear to be directly influenced by price, we find that the younger an individual is when they start using cannabis the less likely they are to quit. Therefore, low cannabis prices lead to early use and because of that they lead to a low quit rate and hence a longer duration of use.

What are the policy implications of the evidence on cannabis and psychosis?

OBJECTIVE

To explore the implications for mental health services, for health education about the risks of cannabis use, and for public policy toward cannabis use of observational evidence that cannabis use is a contributory cause of psychosis.

METHOD

Using comparative analyses of similar evidence for the harmful effects of alcohol, tobacco, and amphetamine use, we considered the relation between observational evidence and action on cannabis. We examined arguments on the grounds of public health prudence for discouraging cannabis use by young individuals. With the assumption that the relation may be causal, we considered recommendations for policy in mental health services, health education, and public policy toward cannabis.

RESULTS

The observational evidence and biological plausibility of the hypothesis that cannabis is a contributory cause of psychosis is at least as strong as evidence for causal relations between heavy alcohol and amphetamine use and psychosis. On public health grounds, there is a good case for discouraging cannabis use among adolescents and young adults. It remains uncertain how best to discourage use and at whom campaigns to reduce cannabis use should be targeted.

CONCLUSIONS

We should discourage young adults seeking treatment in mental health services from using cannabis and inform them of the probable mental health risks of cannabis use, especially of early and frequent use. We must exercise caution in liberalizing cannabis laws in ways that may increase young individuals' access to cannabis, decrease their age of first use, or increase their frequency of cannabis use. We should consider the feasibility of reducing the availability of high-potency cannabis products.