Current Cannabis Use in the United States: Implications for Public Health Research

Cannabis is the most commonly used federally illegal substance in the United States. In 2022, an estimated 62 million people aged 12 years and older (25% of the population) reported using cannabis in the past year.¹ Adult use and frequency of use steadily increased from 2002 to 2019² and from 2021 to 2022,^1,3 whereas adolescent use has decreased or stabilized in recent years.⁴ However, perceived risk of harm has decreased among adolescents and adults.^1–4 Furthermore, high tetrahydrocannabinol (THC)-containing products are increasingly available,⁵ and novel hemp-derived cannabinoids associated with adverse health events are emerging in hemp and cannabis marketplaces.⁶ These issues make for concerning public health trends and underscore a need to disseminate timely information on the status and impact of cannabis-related policies, the potential benefits and harms of cannabis use, and prevention of cannabis use initiation among youths. We provide an overview of the current cannabis landscape and introduce the 12 articles in this AJPH supplement that address these emerging issues.

The increased prevalence of cannabis use over time among persons aged 12 years and older¹ tracks with the growing number of states and territories introducing new cannabis policies. Through early 2024, 38 states, Puerto Rico, Guam, the US Virgin Islands, and the District of Columbia legalized cannabis for adult medical use, and 24 states, Guam, the Northern Mariana Islands, and the District of Columbia legalized cannabis for nonmedical use.⁷

Growing social acceptance of cannabis⁸ coincides with legalization efforts and the public’s perception of cannabis use risk. For example, in 2022, only 25% of people perceived great risk of smoking cannabis once or twice per week.¹ A total of 3.7 million people aged 12 years and older initiated cannabis use in 2022, which is more than a 42% increase from the previous year.^1,3 Efforts to right historic wrongs are improving. Historically, some minority groups—such as African American and Hispanic persons—were disproportionately arrested and incarcerated for cannabis possession.⁹ In states where cannabis use is permitted, there is a growing push for policies to expunge the criminal records of individuals with previous convictions related to cannabis offenses.⁷

In 2024, the cannabis market is a nearly $40 billion industry in the United States, and revenues are expected to increase year over year through 2028, with growth in the number of states that have or are considering legalization.¹⁰ The plant Cannabis sativa has more than 500 chemicals and 100 distinct cannabinoids, with the two most common being delta-9 THC and cannabidiol (CBD).¹¹ Delta-9 THC is the main psychoactive cannabinoid responsible for the cannabis “high” and its addictive potential.¹¹ CBD is another cannabinoid that is nonpsychoactive and is often used therapeutically.¹¹ Cannabis product concentration is often characterized by the ratio of CBD to THC (e.g., 1:1 indicates equal parts CBD and THC), with low CBD–high THC ratios having more psychoactive effects.¹¹ The concentration of THC is increasing in herbal cannabis products.¹² In addition, cannabis is now available in a wider variety of product types, and consumers’ modes of use (e.g., smoking, vaping, eating, drinking, dabbing) reflect the market variety.

Although smoking remains the dominant mode of use, the prevalence of other modes of use and multimodal use are increasing—especially eating or drinking and vaping.^1,13 These alternate modes of use pose unique threats to public health, such as much higher concentrations of THC, exposure to harmful adulterants and excipients, delayed impairment, difficulty managing dose, and unintentionally exposing children to cannabis via edibles that may be mistaken for candy or other foods.¹⁴ In an editorial in this AJPH supplement, Dilley et al. (p. S631) describe an increase in cannabis edible poisonings in children aged 5 years and younger following passage of a bill in Oregon in April 2022 that allowed double the amount of THC in edible servings.

The heterogeneity of product types and ratios of CBD to THC in cannabis products underscore the importance of having a standardized unit of measurement as well as standardized cannabis product labeling to better guide consumer decision-making and support safer patterns of use.¹⁵ Also in this supplement, Meek et al. (p. S681) describe the current regulatory landscape of cannabis product warnings in US states that have legalized nonmedical adult use. In addition, clinical studies analyzing the long-term health effects of increased THC product concentrations are needed. In their analytic essay, Li et al. (p. S639) provide an overview of enhanced methodological approaches for studying the behavioral health effects of high-concentration THC products and call for a prioritization of youth-focused research.

The prevalence of daily or near daily cannabis use is also increasing.^1,3 Frequent use is associated with developing cannabis use disorder (CUD).¹⁶ A total of 19.0 million people aged 12 years and older met Diagnostic and Statistical Manual of Mental Disorders DSM-5-TR criteria for CUD in 2022. CUD prevalence is especially high for persons with a severe mental illness.¹ Other factors are also associated with developing a CUD, including younger age at initiation, dose and duration of cannabis use, product THC concentration, exposure to adverse childhood experiences, and individual genetics.¹⁷ A recent systematic review identified that approximately one in five people who use cannabis develop CUD.¹⁸ Two articles in the AJPH supplement describe recent increases in CUD. Perez-Vilar et al. (p. S694) describe CUD-related medical encounters among Medicare beneficiaries, and Young-Wolff et al. (p. S654) demonstrate increased odds of cannabis use and CUD among adolescents following enactment of local policies allowing storefront cannabis retailers and delivery.

There are currently four cannabis or cannabis-related medications (i.e., Epidiolex, Marinol, Syndros, and Cesamet) that the US Food and Drug Administration has approved for indications such as childhood seizure disorders, anorexia associated with HIV/AIDS, and chemotherapy-induced nausea and vomiting.¹⁹ Although the evidence on effectiveness and safety is mixed, cannabis is used therapeutically to treat chronic pain, posttraumatic stress disorder, and muscle spasms, among other conditions, as well as in palliative or end-of-life care.¹¹ Data on medical use of cannabis are limited, even from states with medical cannabis programs.

In this supplement, Boehnke et al. (p. S685) describe the limited and inconsistent public-facing registry data available from states that have legalized medical cannabis use, particularly with respect to adverse events and product recalls. Enrollment data from these registries have demonstrated that increased passage of adult nonmedical cannabis use laws may be associated with decreased enrollment in medical programs in many US states.²⁰ Decreased enrollment in medical programs may occur because of hurdles individuals face for registering as a cannabis medical patient or because some patients are no longer seeking legal cover for nonmedical adult use through medical programs.^20,21 To explore this phenomenon, Armstrong (p. S673) describes changes in medical cannabis patient activity after Canada’s federal adult nonmedical cannabis legalization in 2018, using monthly data on purchasing frequency and volume that are rarely available in the United States.

Although cannabis use alone is rarely associated with a fatal overdose, its use can lead to a range of short- and long-term adverse cognitive, psychological, and physical outcomes¹¹—especially if regular and heavy use is initiated in adolescence and young adulthood.²² In the short term, this includes impairments in memory, concentration, coordination, judgment, and reaction time as well as an increased risk of acute mood and anxiety disorders and psychotic episodes characterized by paranoia, delusions, and hallucinations.¹¹ In the long term, this includes increased cardiovascular and pulmonary disease risk; pregnancy and neonatal outcomes such as premature birth, lower birth weight, and neonatal intensive care admissions; stunted brain development and longer-term cognitive impairment; lower educational attainment; diminished motivation and life satisfaction; and psychosis and psychotic disorders, such as schizophrenia.^11,22

There are also collateral impacts of cannabis use associated with drug-impaired driving and workplace safety.¹¹ Hultgren et al. (p. S698) briefly describe recent trends in driving under the influence of cannabis and alcohol among young adults in Washington State. Evoy and Victoroff (p. S645) describe a varying prevalence of cannabis use among US workers by demographics and industry and occupation. Understanding these differences can help guide prevention efforts.

Although it is beyond the scope of this editorial to discuss semisynthetic hemp-derived cannabinoids, these products (e.g., those containing delta-8 THC) are relevant in framing public health research priorities. Delta-8 THC exists naturally in the cannabis plant in very small quantities. It can be synthetically converted from hemp-derived CBD to produce larger amounts and is about 50% to 75% as psychoactive as delta-9 THC.⁶ Because hemp is defined federally only in terms of delta-9 THC, there is no limit on the amount of other cannabinoids that can be present in hemp products.

Delta-8 THC products are increasingly appearing in cannabis and hemp marketplaces—the latter being largely unregulated and sold across a variety of outlets and product types, with consumers potentially unaware of delta-8 THC’s psychoactive properties and potential exposure to harmful chemicals used in manufacturing.⁶ Wolf et al., in this supplement (p. S664), describe the Food and Drug Administration’s safety surveillance of adverse event cases associated with the use of cannabinoid hemp products. Similar cautionary tales exist for other semisynthetic hemp-derived products, such as those containing THC-O acetate.⁶ THC-O acetate can be derived from delta-9 or delta-8 THC²³ and is purported to have a stronger effect than delta-9 THC.²⁴ Also in this supplement, Kruger et al. (p. S628) use a social ecological model to better understand the risks associated with THC-O acetate use and promote harm reduction.

The final article in the supplement is an editorial by Schauer (p. S635), who provides suggestions for improving policy-based research in the cannabis space. In the current rapidly evolving legislative environment, it may be important that cannabis researchers use appropriate methods to capture the complexities in this landscape and properly convey research limitations. We hope this supplement informs the work of academicians, public health practitioners, policymakers, community-based organizations, health care providers, and others working on cannabis use policy, research, surveillance, and prevention.