Researchers from University of California San Diego have found that Delta-8 tetrahydrocannabinol (delta-8 THC), a psychoactive compound often sold as a legal alternative to marijuana, is most commonly used in states where marijuana use remains illegal and delta-8 THC sales are unregulated. The findings, published in the American Journal of Preventive Medicine, highlight how gaps in cannabis policy may be inadvertently steering people toward less-regulated substances and have allowed manufacturers to evade restrictions placed on marijuana products.
The study's authors categorized each state based on two key policy types: whether marijuana was permitted for medical or recreational use, and whether delta-8 THC sales were banned, regulated or unregulated. They then analyzed the likelihood of lifetime delta-8 THC use across these groups.
The study was based on a nationally representative survey of 1,523 U.S. adults. Roughly 7.7% of respondents reported using delta-8 THC in their lifetime. But this use was not spread evenly across the country. Adults in states that prohibit all forms of marijuana were about twice as likely (10.9%) to have used delta-8 THC compared to those living in states where adult-use recreational marijuana is legal. Likewise, delta-8 THC use was significantly more common in states with no regulations on its sale (10.5%), compared to states that had taken steps to prohibit (4.5%) or regulate the compound (3.9%). The prevalence of delta-8 THC use was lower among adults in states permitting both medical and nonmedical marijuana (5.5%) and states permitting medical use only (8.5%).
"These findings underscore that people don't just stop using cannabis when their state bans it. They often shift to alternatives that are easier to access, even if they're less well-studied or poorly regulated," said Eric Leas, Ph.D., M.P.H., assistant professor at the Herbert Wertheim School of Public Health and Human Longevity Science at UC San Diego and senior author of the study. Leas is also affiliate faculty at the Qualcomm Institute.
"It's a classic case of unintended consequences in public policy."
The policy loophole driving delta-8 THC use
Delta-8 THC is a chemical cousin to delta-9-tetrahydrocannabinol (delta-9 THC), the primary psychoactive ingredient in marijuana that produces comparable psychotropic effects. Although it occurs naturally in small amounts, most delta-8 THC products are synthesized by chemically converting hemp-derived cannabidiol (CBD), a process that was made more feasible after the 2018 U.S. Farm Bill legalized industrial hemp (defined as cannabis with less than 0.3% delta-9 THC).
Because delta-8 THC can be produced from legally cultivated hemp, many manufacturers argue they can legally make and sell delta-8 THC products as hemp. The Food and Drug Administration (FDA) has issued warnings about delta-8 THC's safety and made a determination that it is not a legal food additive, but federal enforcement has been limited. In the absence of clear federal rules, some states have enacted their own laws, ranging from full bans to no regulation at all. However, most states have made no official determination, leaving delta-8 THC essentially unregulated. Leas has called for this hemp loophole to be closed.
"The numbers in this study confirm a pattern we have seen before in data on delta-8 THC internet searches published in the International Journal of Drug Policy: when safer, regulated access to marijuana is unavailable, people become interested in products that are available, even if they're riskier," said Leas. "Providing legal access to cannabis that meets safety standards and disallowing understudied and poorly regulated products like delta-8 THC could be one way to prioritize public health in our cannabis policies."
Public health concerns and regulatory uncertainty
Unlike regulated marijuana products, which are subject to quality control, dosage limits and labeling requirements in many states, delta-8 THC is often sold in convenience stores and online with little oversight. Some products have been marketed to resemble popular snacks or candies, raising concerns about accidental ingestion, particularly by children. The FDA has received numerous reports of adverse events linked to delta-8 THC and has determined that it does not satisfy the Generally Recognized As Safe standard for food additives and dietary supplements.
"Many people assume that because something is legal, it must be safe," Leas continued. "We've seen rising reports of poisonings and other harmful outcomes tied to delta-8 THC. A regulatory free-for-all only makes that worse."
This new research provides further evidence that delta-8 THC is serving as a substitute in states where traditional cannabis remains illegal or hard to access. This substitution effect, while perhaps predictable, complicates efforts to control cannabis-related harms. In particular, it suggests that prohibiting marijuana may unintentionally drive consumers toward substances that lack both scientific study and regulatory scrutiny.
What comes next
The study authors suggest that clearer, nationwide standards for delta-8 THC could help mitigate potential harms, especially as Congress considers changes to the federal Farm Bill that may close current legal loopholes. At the same time, they urge further research into how and why people choose delta-8 THC over other products.
"Understanding who uses delta-8 THC, how they're using it and what their experiences are can help shape smarter policies," said Leas. "We need to ensure people aren't caught in a policy vacuum, relying on products that fall outside both safety regulations and scientific understanding."
Future studies, the researchers say, should explore motivations behind delta-8 THC use and how policies impact behavior over time. For now, Leas believes this study offers a cautionary tale for lawmakers. "We often think banning a product solves the problem. But when the market moves faster than regulation, it can create new problems," he said. "If we want to reduce harm, we need policies that reflect how people actually behave, not just how we hope they will."
