Research Findings

1. Examining the locations of medical marijuana dispensaries in Los Angeles (October, 2015)

Introduction and Aims: Little is known about the spatial distribution of medical marijuana dispensaries, particularly whether or not sites are disproportionately located in minority or communities with younger populations.  This paper will assess if there is a relationship between medical marijuana dispensaries and neighborhood sociodemographics.

Design and Methods: This study used an ecological, cross-sectional design of 1000 Census tracts from Los Angeles city in 2012 to explore the relationship between neighborhood sociodemographics, structural features of neighborhoods and density of medical marijuana dispensaries. Locations of dispensaries were obtained through a premise survey of all listed dispensaries. Data on neighborhood characteristics were obtained from Geolytics. The study used Bayesian conditionally autoregressive models that include controls for spatial heterogeneity to analyze the data.

Results: Findings show that dispensaries are located in areas that allow for commercial establishments. Results indicate a positive relationship between dispensaries and percent commercially zoned, areas with highway ramp access, density of on- and off-premise alcohol outlets and percent Hispanic residents.

Discussion and Conclusions: In sum, the findings suggest that, likely due to zoning regulations, dispensaries were located in primarily commercially zoned areas with greater road access (as measured by the presence of highway ramps). Given that areas with higher densities of dispensaries also have higher densities of alcohol outlets, future work should examine how this co-location affects neighborhood problems such as crime and violence.

2. The impacts of medical dispensary and neighborhood ecology on marijuana abuse and dependence (September, 2015)

Background. As an increasing number of states liberalize cannabis use and develop laws and local policies, it is essential to better understand the impacts of neighborhood ecology and marijuana dispensary density on marijuana use, abuse, and dependence. We investigated associations between marijuana abuse/dependence hospitalizations and community demographic and environmental conditions from 2001-2012 in California, as well as cross-sectional associations between local and adjacent marijuana dispensary densities and marijuana hospitalizations.

Methods. We analyzed panel population data relating hospitalizations coded for marijuana abuse or dependence and assigned to residential ZIP codes in California from 2001 through 2012 (20,219 space-time units) to ZIP code demographic and ecological characteristics. Bayesian space-time misalignment models were used to account for spatial variations in geographic unit definitions over time, while also accounting for spatial autocorrelation using conditional autoregressive priors. We also analyzed cross-sectional associations between marijuana abuse/dependence and the density of dispensaries in local and spatially adjacent ZIP codes in 2012.

Results. An additional one dispensary per square mile in a ZIP code was cross-sectionally associated with a 6.8% increase in the number of marijuana hospitalizations (95% credible interval 1.033, 1.105) with a marijuana abuse/dependence code. Other local characteristics, such as the median household income and age and racial/ethnic distributions, were associated with marijuana hospitalizations in cross-sectional and panel analyses.

Conclusions. Prevention and intervention programs for marijuana abuse and dependence may be particularly essential in areas of concentrated disadvantage. Policy makers may want to consider regulations that limit the density of dispensaries.

3. Distribution of Medical Marijuana Dispensaries from 2007 to 2014 in Los Angeles, CA (Research Brief 2015-01, March 2015)

4. Physical Availability of Medical Marijuana and Marijuana Use (September 2014)

Freisthler, B. & Gruenewald, P.J. (2014). Examining the relationship between the physical availability of medical marijuana and marijuana use across fifty California cities. Drug and Alcohol Dependence, 143, 244-250. doi: 10.1016/j.drugalcdep.2014.07.036

Background. The purpose of the current study is to assess statistical associations between individual demographic and personality characteristics, the city-level physical availability of marijuana (as measured through densities per roadway mile of storefront dispensaries and delivery services), and the incidence and prevalence of marijuana use.    

Method. Individual level data on marijuana use were collected during a telephone survey of 8,853 respondents living in 50 mid-size cities in California. Data on medical marijuana dispensaries and delivery services were obtained via seven different websites and official city lists. Three outcome variables pertaining to lifetime, past year use, and frequency of past 28-day use were analyzed using random effects logistic models (for lifetime and past year use) and random effects tobit models (for frequency of past 28-day use).

Results. The current study finds that the total physical availability of medical marijuana through dispensaries and delivery services per roadway mile at the city-level is positively related to current marijuana use and greater frequency of use, controlling for a variety of demographic and personality characteristics.  As expected, current physical availability of marijuana was unrelated to lifetime use.

Conclusions. Regulations on the number and densities of marijuana outlets may be a sufficient means to restrain overall levels of marijuana use within cities.  However, alternative use of delivery services may also provide easy access to marijuana and mitigate these effects.

5. The Economic Geography of Medical Marijuana Dispensaries in California (July, 2014)

Morrison, C., Gruenewald, P.J., Freisthler, B., Ponicki, W.R., and Remer, L.G. (2014). The economic geography of medical marijuana dispensaries in California.  International Journal of Drug Policy, 25, 508-515. doi: 10.1016/j.drugpo.2013.12.009

Background. The introduction of laws that permit the use of marijuana for medical purposes has led to the emergence of a medical marijuana industry in some US states. This study assessed the spatial distribution of medical marijuana dispensaries according to estimated marijuana demand, socioeconomic indicators, alcohol outlets and other socio-demographic factors.

Method. Telephone survey data from 5,940 residents of 39 California cities were used to estimate social and demographic correlates of marijuana demand. These individual-level estimates were then used to calculate aggregate marijuana demand (i.e. market potential) for 7,538 census block groups. Locations of actively operating marijuana dispensaries were then related to the measure of demand and the socio-demographic characteristics of census block groups using multilevel Bayesian conditional autoregressive logit models.

Results. Marijuana dispensaries were located in block groups with greater marijuana demand, higher rates of poverty, alcohol outlets, and in areas just outside city boundaries. For the sampled block groups, a 10% increase in demand within a block group was associated with 2.4% greater likelihood of having a dispensary, and a 10% increase in the city-wide demand was associated with a 6.7% greater likelihood of having a dispensary.

Conclusion. High demand for marijuana within individual block groups and within cities is related to the location of marijuana dispensaries at a block-group level. The relationship to low income, alcohol outlets and unincorporated areas indicates that dispensaries may open in areas that lack the resources to resist their establishment.

6. Availability of Tobacco Products Associated with use of Marijuana Cigars (Blunts) (January, 2014)

Lipperman-Kreda, S., Lee, J., Morrison, C., & Freisthler, B. (2014). Availability of tobacco products associated with use of marijuana cigars (blunts). Drug and Alcohol Dependence, 134, 337-342.

Objectives: This study examines factors associated with availability of tobacco products for marijuanacigars (i.e., blunts) in 50 non-contiguous mid-sized California communities.

Methods: The study is based on data collected in 943 tobacco outlets. Neighborhood demographics,community adult marijuana prevalence, medical marijuana policy and access to medical marijuanadispensaries and delivery services were included.

Results: Multilevel logistic regression analyses indicated that compared with small markets, availabil-ity of tobacco products associated with use of blunts was significantly higher in convenience stores,smoke/tobacco shops and liquor stores. None of the neighborhood demographics were associated withavailability of blunt wrappers and only a small percent of Whites was positively associated with avail-ability of blunt cigars, small cigars or cigarillos at the store. Controlling for outlet type and neighborhooddemographics, higher city prevalence of adult marijuana use was associated with greater availabilityof blunt wrappers. Also, policy that permits medical marijuana dispensaries or private cultivation waspositively associated with availability of tobacco products for blunts. Density of medical marijuana dis-pensaries and delivery services, however, was negatively associated with greater availability of theseproducts at tobacco outlets.

Conclusions: Results suggest that availability of tobacco products associated with blunts is similar in neigh-borhoods with different socioeconomic status and racial and ethnic composition. Results also suggest theimportant role that community norms that support marijuana use or legalization of medical marijuanaand medical marijuana policy may play in increasing availability of tobacco products associated withblunts.

7. Study: Pot Shop Security Could Reduce Crime (February, 2013)

Freisthler, B., Kepple, N.J., Sims, R., & Martin, S.E. (2013). Evaluating medical marijuana dispensary policies: Spatial methods for the study of environmentally-based interventions. American Journal of Community Psychology, 51, 278-288.

In 1996, California was the first state to pass a Compassionate Use Act allowing for the legal use of marijuana for medical purposes. Here we review several current policy and land use environmental interventions designed to limit problems related to the influx of medical marijuana dispensaries across California cities. Then we discuss the special challenges, solutions, and techniques used for studying the effects of these place-based policies. Finally, we present some of the advanced spatial analytic techniques that can be used to evaluate the effectiveness of environmental interventions, such as those related to reducing problems associated with the proliferation of medical marijuana dispensaries. Further, using data from a premise survey of all the dispensaries in Sacramento, this study will examine what characteristics and practices of these dispensaries are related to crime within varying distances from the dispensaries (e.g., 100, 250, 500, and 1000 feet). We find that some security measures, such as security cameras and having a door man outside, implemented by medical marijuana dispensary owners might be effective at reducing crime within the immediate vicinity of the dispensaries.

8. "The Social Ecology of Substance Use" Presentation (June, 2012)

9. Exploring the Ecological Association between Crime and Medical Marijuana Dispensaries (September, 2011)

Kepple, N.J. & Freisthler, B. (2012). Exploring the ecological association between crime and medical marijuana dispensaries. Journal of Studies on Alcohol and Drugs, 73, 523-530.

Objective: Routine activities theory purports that crime occurs in places with a suitable target, motivated offender, and lack of guardianship. Medical marijuana dispensaries may be places that satisfy these conditions, but this has not yet been studied. The current study examined whether the density of medical marijuana dispensaries is associated with crime.
Method: An ecological, cross-sectional design was used to explore the spatial relationship between density of medical marijuana dispensaries and two types of crime rates (violent crime and property crime) in 95 census tracts in Sacramento, CA, during 2009. Spatial error regression methods were used to determine associations between crime rates and density of medical marijuana dispensaries, controlling for neighborhood characteristics associated with routine activities.
Results: Violent and property crime rates were positively associated with percentage of commercially zoned areas, percentage of one-person households, and unemployment rate. Higher violent crime rates were associated with concentrated disadvantage. Property crime rates were positively associated with the percentage of population 15–24 years of age. Density of medical marijuana dispensaries was not associated with violent or property crime rates.
Conclusions: Consistent with previous work, variables measuring routine activities at the ecological level were related to crime. There were no observed cross-sectional associations between the density of medical marijuana dispensaries and either violent or property crime rates in this study. These results suggest that the density of medical marijuana dispensaries may not be associated with crime rates or that other factors, such as measures dispensaries take to reduce crime (i.e., doormen, video cameras), may increase guardianship such that it deters possible motivated offenders.

10. Evaluating Medical Marijuana Dispensary Policies: Spatial Methods for the Study of Environmentally-Based Interventions, (September, 2011)