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A new Columbia University Mailman School of Public Health study finds that using cannabis together with nicotine and tobacco products is common—especially among people who vape. The research also shows both vaped and smoked cannabis have increased over time, with more people starting use than quitting.

Until now, how often and why young adults use cannabis, and the specific ways they use it, has received limited attention. The findings appear in Tobacco Induced Diseases.

Researchers found that young adults in the New York City area—including those who don’t use nicotine—reported using multiple cannabis forms such as vapes, edibles, and topicals. Cannabis is the third most commonly used drug worldwide; in 2023 an estimated 61.8 million people—about 22% of Americans ages 12 and older—said they had used marijuana at least once in the past year.

“Cannabis use in the U.S. represents a multifaceted and evolving public health challenge that has, for too long, been overlooked,” said Katlyn McGraw, Ph.D., postdoctoral research scientist of Environmental Health Sciences at Columbia Mailman School.

“We aimed to better understand use patterns and potential exposure to cannabis-related contaminants and associated health effects. Our findings show that cannabis use is diverse, complex, and growing —underscoring the need for further investigation.”

To track trends and product types, the team analyzed data from the VapeScan longitudinal study, set up to evaluate subclinical health effects of e-cigarette use. The cohort included 372 adults, ages 18–50, in the New York City region, assessed between 2021 and 2024 regardless of cannabis use.

Participants were seen at three points: baseline (visit 1), about 12 months later (visit 2), and about 24 months later (visit 3). At visit 1 participants answered questions about cannabis use; a more detailed questionnaire at visit 2 captured longitudinal trends and specific consumption methods. Participants were grouped as exclusive cannabis users, exclusive e-cigarette users, non–substance users, or dual users—those reporting daily or some-day use of both e-cigarettes and cigarettes.

At visit 1:
– 34% reported dual substance use
– 4% reported exclusive cannabis use
– 35% reported e-cigarette use without cannabis
– 28% reported no substance use

By visit 2, 59% of participants reported cannabis use:
– 29% vaped cannabis
– 28% smoked cannabis
– 51% consumed edibles
– 32% used CBD products
– 4% used topical cannabis

Frequency and intensity varied by product type. Importantly, self-reported vaped or smoked cannabis use shifted between visits: 21% of participants were new users at visit 2, while only 6% of those who vaped or smoked at visit 1 had quit. Rates of combined cannabis and e-cigarette use were similar for men and women.

“Frequent cannabis use is becoming more widespread and will likely continue to rise with changing social norms, policy liberalization, and the increasing availability and promotion of cannabis products,” McGraw noted.

“The prevalence of cannabis use among teens and young adults is increasing, as is the variety of products—edibles, concentrates, vapes—adding to the complexity of studying health effects.

“As the third most widely used drug globally, understanding the health implications of cannabis is essential,” says Ana Navas-Acien, MD, Ph.D., Columbia Mailman School Leon Hess Professor and Chair, Environmental Health Sciences.

“Our study highlights the importance of assessing cannabis exposure, including potential contaminants, and underscores that cannabis use is multifaceted. Regulatory policies and shifting consumer preferences further complicate efforts to accurately characterize exposure. Strengthening public health education that informs young adults about the compounded risks of cannabis–nicotine co-use is a first step.”

More information: Cannabis Products and Trends in a Cohort of Young Adults: The Longitudinal VapeScan Study, Tobacco Induced Diseases (2025).

This article was adapted from an original report published on medicalxpress.com. All rights belong to the original publisher.