Changes in Marijuana Use Across the 2012 Washington State Recreational Legalization: Is Retrospective Assessment of Use Before Legalization More Accurate?

Life-course Accumulated Cannabis Use and Recent Cannabis-related Problems in the Washington Panel Survey

BACKGROUND

Previous studies have only investigated the short-term association of recent cannabis use with cannabis-related problems, without accounting for the onset, duration, and variations in frequency of use in the life-course.

METHODS

We obtained data from the Washington panel survey during 2014-2016. We constructed accumulated lifetime exposure to cannabis use, heavy drinking (5+ drinks on one occasion), and cigarette pack-years from age of onset based on a series of decades-based questions on cannabis use and heavy drinking, and tobacco use history. We used Generalized Estimating Equation with Poisson distribution to investigate the association between accumulated cannabis use and the past-6-month CUDIT score. We adjusted for accumulated heavy drinking and cigarette pack-years, substance co-use variables, demographics, and applied survey weights.

RESULTS

We found strong and statistically significant correlations for the lifetime measures across the four panel surveys, indicating that the life-course measures of cannabis use and heavy drinking were largely reliable. We found a statistically significant relationship between the lifetime accumulated exposure to cannabis and CUDIT. The results were robust to the inconsistencies in reported frequencies and onset age across panel surveys.

CONCLUSIONS

This study established the relationship between lifetime exposure to cannabis and cannabis-related problems in a representative sample of drinkers and marijuana users in Washington state. We have also provided test-retest validity and question details for the decades-based cannabis and heavy drinking measures to facilitate their use in future studies of cannabis and alcohol-related outcomes.

Higher Concentration of Marijuana Dispensaries in Neighborhoods with More Disadvantage Following Legalization in Washington

Washington is one of 21 states that have legalized recreational marijuana resulting in neighborhoods that have experienced a change in physical environment with the emergence of dispensaries. This study examines the selection of dispensaries into disadvantage area, incorporating local policies and neighborhood characteristics. Marijuana and alcohol sales data were from the Washington State Liquor and Cannabis Board; and neighborhood characteristics were drawn from the American Community Survey 2010-2016 5-year estimates. Using factor analysis we created a neighborhood disadvantage index where census tracts were stratified into disadvantaged tertiles; and counties were stratified by urban/rural status. We examined the association between dispensaries, neighborhood characteristics, and local marijuana policies using Negative Binomial Regression with a natural log of land area as an offset, separately for 2014-2016. Dispensaries opened in high-disadvantaged CTs in 2014 and then dispersed across the state while retaining higher concentrations in disadvantaged urban CTs. Marijuana-specific policies (allotted dispensaries and retail cap) were found to be predictors of marijuana dispensary density. This study provides evidence that marijuana dispensaries were disproportionately located in areas with greater disadvantage. State and local marijuana policies emerged as important predictors, underscoring the importance of designing thoughtful and equitable license allocation procedures and policies.

Characteristics of the Washington cannabis market from 2014 to 2016

BACKGROUND

The state of Washington legalized cannabis for adult use in 2012 and retail stores began to open in 2014. While details of the legal market have been tracked by the state, the total market for cannabis and characteristics of purchasers can only be identified through surveys.

METHODS

Six cross-sectional samples of the Privatization of Spirits in Washington (PSW) surveys were collected between January 2014 and October 2016 with two in each year. Random digit dial procedures were used to recruit a sample aged 18 and older, with 40% of cases from mobile phones. A total of 5492 respondents participated. Analyses of the population-weighted sample utilized purchasing amounts and frequencies, use frequency and related measures to estimate total and mean amounts and expenditures. Sensitivity analyses were conducted for key assumptions.

RESULTS

The market for cannabis flower is estimated to have increased from 158 metric tons and $1.23 billion in 2014 to 222 metric tons and $1.7 billion in 2016, with little change from 2014 to 2015. Purchases from legal sources, retail and dispensaries, were estimated at 69% of the total market. Daily or near daily (DND) users accounted for about 83% of sales in 2014, rising to 91% in 2016. The prevalence of past year use rose substantially from 25% in 2014 to 32% in 2016, with DND use rising from 10.2 to 11.3%. Average purchase amounts for DND users rose from 291 g in 2014 to 374 g in 2016, while mean amounts among non-DND users declined from 78 to 28.6 g.

CONCLUSIONS

The expansion of retail cannabis stores in Washington appears to have led to increased market size in 2016 with all of the increase attributed to DND users. Frequent users may be important to consider in legalization evaluations.

Estimating Usual Grams per Day of Marijuana Use from Purchases

BACKGROUND

Quantifying average amounts of marijuana used per day or per occasion of use helps inform understanding population-level patterns of use and use-related harm, but better estimates and estimation methods are needed. Users have difficulty in reporting use amounts, but purchase amounts may be more clearly recalled.

METHODS

Measures of individual's use and purchasing frequency and details of purchases such as the amounts and products bought and the cost of these were collected in six cross-sectional representative surveys of the population 18 and older in the state of Washington from 2014 to 2016. Analyses utilize purchase information on both flower and other marijuana products to estimate mean amounts per use day and predict use amounts for non-purchasers.

RESULTS

Mean marijuana use per use day among purchasers was 1.35 grams and non-purchasers estimated mean use amount per day was 0.71 grams. Lower mean use per day was a found for women and the most frequent users. Based on these estimates, total past year marijuana use for purchasers had a mean of 184.8 grams and the mean for non-purchasers was 28 grams.

CONCLUSIONS

Methods based on purchasing details can be used to estimate individual's marijuana quantity per occasion and total use amount per year, providing additional outcome measures for analyses of predictors of individual marijuana consumption and facilitating more detailed analyses of risks for marijuana harms.

Cannabis Vaping Among Youth and Young Adults: a Scoping Review

Purpose of Review

The purpose of this review was to describe the state-of-the-literature on research specific to cannabis vaping among youth and young adults.

Recent Findings

Out of 1801 records identified, a total of 202 articles met eligibility criteria for inclusion in this review. Most of this literature (46.0% of studies) was specific to the health effects of cannabis vaping, particularly EVALI (e-cigarette and vaping associated lung injury). Other research areas identified in the review included the etiology (24.3%) and epidemiology (24.8%) of cannabis vaping, in addition to articles on regulation (8.4%) and marketing (5.5%) of the same.

Summary

Cannabis vaping is increasingly common among youth and young adults and more prevalent is settings where recreational use for adults has been legalized. The literature documents a number of negative health effects of cannabis vaping for young people, along with risk factors and reasons for the same.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40429-022-00413-y.

GEOGRAPHICAL ACCESS TO RECREATIONAL MARIJUANA

We investigate whether adult marijuana use in Washington responds to increased local access as measured by drive time to the nearest legal marijuana retailer as well as measures of retail density. Using survey data from the Behavioral Risk Factor Surveillance System, we find that as retailers open closer to where they live, more individuals use marijuana and more frequently. These effects are concentrated among young adults (ages 18-26), women, and rural residents. Controlling for distance to the nearest retailer, we find that whether retail density affects marijuana use depends on how it is measured.

The effect of cannabis policies on treatment outcomes for cannabis use among U.S. adults

BACKGROUND

Research has explored the impact of various medical cannabis policies on substance use treatment admission in recent years, but we know little about factors related to participants' treatment engagement and outcome. To fill this gap in the existing literature, this study used national data to examine the influence of cannabis policies (decriminalized, medical, and recreational) and referral sources (criminal justice vs. voluntary) on treatment completion and length of stay.

METHODS

Data came from the Treatment Episode Data Set-Discharge (2006-2017) on adults 18+ whose primary drug at treatment admission was cannabis. Difference-in-difference analyses using logistic regression examined the effect of cannabis policies on outpatient treatment completion (yes/no; n = 2,192,807) and length of stay (more/fewer than 90 days; n = 1,863,585) in those with a criminal justice or voluntary referral source.

RESULTS

Cannabis policy was not associated with treatment completion in either those with a criminal justice or voluntary referral source. Compared to individuals in states where cannabis use was strictly illegal, those in states with a decriminalization policy were less likely to stay in treatment for 91+ days regardless of the referral source.

CONCLUSIONS

Cannabis policy appears to have a differential effect on treatment completion versus length of stay, with policy having no impact on successful treatment completion. Specifically, we found that decriminalization policies hinder treatment engagement past 90 days. In this sense, length of stay may be a more useful measure of treatment outcome for research than treatment completion moving forward. Furthermore, our study found that neither medical nor recreational policies affected length of stay or treatment completion, regardless of referral source.

Cannabis use while trying to conceive: a prospective cohort study evaluating associations with fecundability, live birth and pregnancy loss

STUDY QUESTION

Is cannabis use assessed via urinary metabolites and self-report during preconception associated with fecundability, live birth and pregnancy loss?

SUMMARY ANSWER

Preconception cannabis use was associated with reduced fecundability among women with a history of pregnancy loss attempting pregnancy despite an increased frequency of intercourse.

WHAT IS KNOWN ALREADY

Cannabis use continues to rise despite limited evidence of safety during critical windows of pregnancy establishment. While existing studies suggest that self-reported cannabis use is not associated with fecundability, self-report may not be reliable.

STUDY DESIGN, SIZE, DURATION

A prospective cohort study was carried out including 1228 women followed for up to six cycles while attempting pregnancy (2006 to 2012), and throughout pregnancy if they conceived.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women aged 18-40 years with a history of pregnancy loss (n = 1228) were recruited from four clinical centers. Women self-reported preconception cannabis use at baseline and urinary tetrahydrocannabinol metabolites were measured throughout preconception and early pregnancy (up to four times during the study: at baseline, after 6 months of follow-up or at the beginning of the conception cycle, and weeks 4 and 8 of pregnancy). Time to hCG-detected pregnancy, and incidence of live birth and pregnancy loss were prospectively assessed. Fecundability odds ratios (FOR) and 95% CI were estimated using discrete time Cox proportional hazards models, and risk ratios (RRs) and 95% CI using log-binomial regression adjusting for age, race, BMI, education level, baseline urine cotinine, alcohol use and antidepressant use.

MAIN RESULTS AND THE ROLE OF CHANCE

Preconception cannabis use was 5% (62/1228), based on combined urinary metabolite measurements and self-report, and 1.3% (11/789) used cannabis during the first 8 weeks of gestation based on urinary metabolites only. Women with preconception cannabis use had reduced fecundability (FOR 0.59; 95% CI 0.38, 0.92). Preconception cannabis use was also associated with increased frequency of intercourse per cycle (9.4 ± 7 versus 7.5 ± 7 days; P = 0.02) and higher LH (percentage change 64%, 95% CI 3, 161) and higher LH:FSH ratio (percentage change 39%, 95% CI 7, 81). There were also suggestive, though imprecise, associations with anovulation (RR 1.92, 95% CI 0.88, 4.18), and live birth (42% (19/45) cannabis users versus 55% (578/1043) nonusers; RR 0.80, 95% CI 0.57, 1.12). No associations were observed between preconception cannabis use and pregnancy loss (RR 0.81, 95% CI 0.46, 1.42). Similar results were observed after additional adjustment for parity, income, employment status and stress. We were unable to estimate associations between cannabis use during early pregnancy and pregnancy loss due to limited sample size.

LIMITATIONS, REASONS FOR CAUTION

Owing to the relatively few cannabis users in our study, we had limited ability to make conclusions regarding live birth and pregnancy loss, and were unable to account for male partner use. While results were similar after excluding smokers, alcohol use and any drug use in the past year, some residual confounding may persist due to these potential co-exposures.

WIDER IMPLICATIONS OF THE FINDINGS

These findings highlight potential risks on fecundability among women attempting pregnancy with a history of pregnancy loss and the need for expanded evidence regarding the reproductive health effects of cannabis use in the current climate of increasing legalization.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (Contract numbers: HHSN267200603423, HHSN267200603424, HHSN267200603426, HHSN275201300023I). Jeannie G. Radoc has been funded by the National Institutes of Health Medical Research Scholars Program, a public-private partnership supported jointly by the National Institutes of Health and generous contributions to the Foundation for the National Institutes of Health from the Doris Duke Charitable Foundation (DDCF Grant # 2014194), Genentech, Elsevier, and other private donors. The authors report no conflict of interest in this work and have nothing to disclose.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT00467363.

Male Preconception Marijuana Use and Spontaneous Abortion: A Prospective Cohort Study

BACKGROUND

Male marijuana use has increased steadily over the last decade, but its effect on risk of spontaneous abortion to our knowledge has not been studied.

METHODS

We analyzed data from Pregnancy Study Online, a North American prospective cohort study of pregnancy planners (2013-2019). During the preconception period, male and female participants completed baseline questionnaires on demographics, medical history, and behavioral factors, including marijuana use. Female participants identified pregnancy losses on bimonthly follow-up questionnaires and questionnaires completed in early and late pregnancy. We categorized frequency of male marijuana use in the 2 months before baseline as none, <1 time/week, or ≥1 time/week. We estimated the association between preconception male marijuana use and spontaneous abortion, adjusting for male and female confounders.

RESULTS

Among 1535 couples who conceived during follow-up, 9% of men reported preconceptional marijuana use <1 time/week and 8% ≥1 time/week. Nineteen percent of pregnancies ended in spontaneous abortion. Compared with no use, adjusted hazard ratios (HRs) for male marijuana use were 1.1 (95% confidence interval [CI] = 0.64, 1.7) for <1 time/week and 2.0 (95% CI = 1.2, 3.1) for ≥1 time/week. The association for ≥1 time/week persisted after restricting to couples where the female partner did not use marijuana (HR = 2.0, 95% CI = 1.1, 3.3), and was stronger for losses at <8 weeks' gestation (HR = 2.5, 95% CI = 1.4, 4.3) and among males aged ≥35 years (HR = 4.1, 95% CI = 1.54, 11).

CONCLUSIONS

Couples with male partners who used marijuana ≥1 time/week during preconception had greater risk of spontaneous abortion than couples with males who did not use marijuana.

Extending the Harm to Others Paradigm: Comparing Marijuana- and Alcohol-Attributed Harms in Washington State

Harms attributed to others' alcohol use have been extensively studied in the US and internationally, but no studies have measured harms from others' marijuana use. We utilize data from five cross-sectional waves of a survey series with representative samples of Washington state residents conducted every 6 months from 2014 to 2016, after the legalization of adult use marijuana. Harms attributed to others' drinking and to others' marijuana use included family and financial problems, assault, harassment, and vandalism experiences, and accidents due to impaired drivers. Past year harms attributed to others' marijuana use were reported by 8.4% of the sample, while 21.3% reported alcohol-attributed harms and 4.3% experienced both. Women were more likely to experience harms from either substance. While heavy drinkers were most likely to experience alcohol harms from others' use, frequent marijuana users reported the least harms from others. About three times as many individuals reported harassment, vandalism, or family problems attributed to someone's alcohol use compared to those harms attributed to someone's marijuana use, with a smaller ratio seen for financial trouble and a wider ratio for physical harm. Harms attributed to other's marijuana use in Washington were found to be substantial, but lower than harms from others' drinking.

Assessing the public health impacts of legalizing recreational cannabis use: the US experience

The sale of cannabis for adult recreational use has been made legal in nine US states since 2012, and nationally in Uruguay in 2013 and Canada in 2018. We review US research on the effects of legalization on cannabis use among adults and adolescents and on cannabis-related harms; the impact of legalizing adult recreational use on cannabis price, availability, potency and use; and regulatory policies that may increase or limit adverse effects of legalization. The legalization of recreational cannabis use in the US has substantially reduced the price of cannabis, increased its potency, and made cannabis more available to adult users. It appears to have increased the frequency of cannabis use among adults, but not so far among youth. It has also increased emergency department attendances and hospitalizations for some cannabis-related harms. The relatively modest effects on cannabis use to date probably reflect restrictions on the number and locations of retail cannabis outlets and the constraints on commercialization under a continued federal prohibition of cannabis. Future evaluations of legalization should monitor: cannabis sales volumes, prices and content of tetrahydrocannabinol; prevalence and frequency of cannabis use among adolescents and adults in household and high school surveys; car crash fatalities and injuries involving drivers who are cannabis-impaired; emergency department presentations related to cannabis; the demand for treatment of cannabis use disorders; and the prevalence of regular cannabis use among vulnerable young people in mental health services, schools and the criminal justice system. Governments that propose to legalize and regulate cannabis use need to fund research to monitor the impacts of these policy changes on public health, and take advantage of this research to develop ways of regulating can-nabis use that minimize adverse effects on public health.

Thermographic detection and quantification of THC in oral fluid at unprecedented low concentrations

With recent changes in the legalization of cannabis around the world, there is an urgent need for rapid, yet sensitive, screening devices for testing drivers and employees under the influence of cannabis at the roadside and at the workplace, respectively. Oral fluid lateral flow immunoassays (LFAs) have recently been explored for such applications. While LFAs offer on-site, low-cost and rapid detection of tetrahydrocannabinol (THC), their nominal detection threshold is about 25 ng/ml, which is well above the 1-5 ng/ml per se limits set by regulations. In this paper, we report on the development of a thermo-photonic imaging system that utilizes the commercially available low-cost LFAs but offers detection of THC at unprecedented low concentrations. Our reader technology examines photothermal responses of gold nanoparticles (GNPs) in LFA through lock-in thermography (LIT). Our results (n = 300) suggest that the demodulation of localized surface plasmon resonance responses of GNPs captured by infrared cameras allows for detection of THC concentrations as low as 2 ng/ml with 96% accuracy. Quantification of THC concentration is also achievable with our technology through calibration.

Washington's privatization of liquor: effects on household alcohol purchases from Initiative 1183

BACKGROUND AND AIMS

Washington Initiative 1183 (I-1183), a 2012 law that privatized liquor retail sales and distribution in Washington State, USA, has had two opposing effects on liquor purchases: it has increased access to liquor and imposed new fees on retailers and distributors. This study aimed to estimate the effect of I-1183 on monthly alcohol purchases during the post-I-1183 period (June 2012-December 2014) compared with the pre-I-1183 period (January 2010-May 2012).

DESIGN

DIFFERENCES-IN-DIFFERENCES STUDY: Setting and participants The study included households participating in the Nielsen Consumer Panel Dataset living in metropolitan and surrounding areas in Washington State and 10 control states. Measurements Outcomes were alcohol purchases by type (ounces of liquor, wine, beer and total alcohol or ethanol). Findings I-1183 was associated with a 6.34-ounce (P < 0.001) and a 2.01-ounce (P < 0.001) increase in monthly liquor and ethanol purchases, respectively, per household in the post-policy period spanning 31 months compared with monthly purchases in control states. In a longitudinal subgroup analysis, low and moderate alcohol purchasers increased monthly purchases of ethanol and high purchasers decreased purchases of ethanol. Conclusions Enacting 'Washington Initiative 1183', a law that privatized sale and distribution of liquor and imposed new fees on retailers and distributors, appears to have been associated with an approximate 82% increase in monthly liquor purchases and 26% increase in monthly ethanol purchases by households in metropolitan and surrounding areas in Washington State, USA.

Subgroup trends in alcohol and cannabis co-use and related harms during the rollout of recreational cannabis legalization in Washington state

BACKGROUND

The US state of Washington legalized recreational cannabis in 2012; how this impacted the co-use of cannabis and alcohol in the population overall and among key subgroups has not been examined. The aim of this study is to investigate changes in patterns of alcohol- and cannabis use and alcohol-related harms during the rollout of retail recreational cannabis stores.

METHODS

Data come from six cross-sectional samples recruited between January 2014-October 2016 via Random Digit Dial procedures (N = 5492). Survey-weighted multivariable regression adjusting for gender, age, race/ethnicity, education, employment, marital status, cannabis use, and survey year were used for statistical analyses.

RESULTS

In the sample overall, no significant changes were observed in any alcohol use measures between 2014-2016, while the prevalence of cannabis use significantly (P < 0.05) increased from 25.0% to 31.7%, the prevalence of alcohol-related harms at home significantly decreased from 2.1% to 1.0%, and the prevalence of alcohol-related financial harms decreased from 1.5% to 0.8%. Both women and men significantly increased any cannabis use, while women also experienced significantly fewer alcohol-related harms at home and financial harms over time, and increases in the prevalence of cannabis users/non-drinkers. Those 18-29 years old significantly reduced the number of drinking days and overall volume in the past 30 days, and those 30-49 years old significantly decreased alcohol-related harms at home and financial harms. Those 50+ years old significantly increased any cannabis use and simultaneous use of cannabis and alcohol. Non-cannabis users slightly decreased average number of drinks/day, and cannabis users significantly decreased alcohol-related financial harms.

CONCLUSIONS

Between 2014-2016, the years during and immediately following the introduction of legal recreational cannabis stores in Washington state, there were no significant changes in cannabis and alcohol co-use or overall alcohol consumption. The only significant changes in the sample overall were an increase in any cannabis use and decreases in alcohol-related harms at home and alcohol-related financial harms.

The Risk of Cardiovascular Events on Cannabis' Highest Day

Knowledge of the acute cardiovascular effects of cannabis consumption remains largely unknown and is important given the changing landscape of legalization of recreational cannabis use. "4/20" is an annual event where many individuals gather to consume cannabis. An increased risk of adverse health events such as motor vehicle accidents has previously been reported to occur on "4/20." In this study, population-based administrative databases in Ontario, Canada, were used to evaluate the association between "4/20" and cardiovascular events. An increased risk of cardiovascular events on a population level was not observed on "4/20." Additional research into the changes in the prevalence of the use of cannabis with recreational legalization and acute and chronic risk with cannabis use is suggested.

Spirits purchasing and marijuana use behaviors of risky drinkers in the state of Washington from 2014 to 2016

BACKGROUND

Few studies have evaluated alcoholic beverage purchasing behaviors, which are relevant to the design and effectiveness of alcoholic beverage control policies. Focusing on spirits purchasing among spirits drinkers, this study compares purchasing behaviors between risky and non-risky drinkers and across drinking patterns among those observed drinking at both levels.

METHODS

A rolling panel of 794 spirits drinkers in the state of Washington were surveyed between two and five times at 6-month intervals during 2014, 2015 and 2016 regarding their alcohol use, spirits purchasing and marijuana use frequency. Purchasing behaviors assessed for spirits were the frequency of purchasing and the travel time, unit cost, bottle size and store type from the respondents most recent purchase. Alcohol use was categorized at each measurement as risky or not using US NIAAA guidelines.

RESULTS

Risky drinkers were more likely to purchase spirits, purchase spirits more frequently, purchase larger spirits containers and use marijuana occasionally, but not frequently. Among drinkers who were risky only in some survey waves, during risky waves they were more likely to purchase more frequently, pay less per liter for spirits purchased, buy larger sized containers of spirits and use marijuana occasionally.

CONCLUSIONS

Drinkers chose to purchase lower cost spirits in larger containers when they were drinking more heavily compared to times when they were drinking within US low-risk guidelines. Findings also support complementarity between heavier drinking and marijuana use among spirits drinkers in a state with legal recreational marijuana sales.