A new scientific study has found that nearly half of all Colorado cannabis labels on products sold, list THC levels that are significantly higher than what independent lab tests reveal. The yearlong “secret shopper” study, led by researchers at the University of Colorado Boulder and published in Scientific Reports, analyzed 277 cannabis products purchased from 52 licensed stores across the state. Forty-four percent of flower samples were labeled with THC potencies at least 15% higher than what testing showed.
The results call into question how much trust consumers can place in Colorado’s cannabis labels, and whether the state’s regulatory testing system is giving consumers the transparency they expect.
Key Takeaways
- Nearly half of cannabis flower products in Colorado were found to have inflated THC levels on product labels.
- The CU Boulder study analyzed 277 samples from licensed dispensaries statewide.
- Concentrates had more accurate labels but still often overstated potency.
- Experts cite inconsistent lab standards and market pressure for high-THC numbers.
- Colorado’s Marijuana Enforcement Division is reviewing the findings.
THC Testing Shows Widespread Colorado Cannabis Labels Inaccuracy
Greg Giordano, a lead researcher, said clear and honest cannabis labels matter for both public trust and health research.
“It’s important that we have accurate cannabis product labels so people who do that kind of research, looking at risks, potential risks, know what’s in the product,” Giordano told CPR News.
Lab testing was conducted by MedPharm Research, a licensed Colorado facility. While the study excluded edibles, it included both flower and concentrate products. Of the inaccurately labeled flower samples, most overstated THC levels by at least 15%.
By contrast, concentrates, such as vape cartridges, were more often accurate but still generally tested lower than their label claims.
Industry Pushback and Market Pressures
Some cannabis industry leaders questioned the study’s implications. Paul Jacobson, co-founder of the multistate brand Rove, said differences between testing labs and natural variation in cannabis flower can lead to inconsistent results.
“I don’t think that there is like a nefarious thing going on, where all the farms are doing something to trick the consumer,” Jacobson said. “You’re smoking high-potency weed regardless.”
Mason Tvert, a spokesperson for the industry group Colorado Leads, pointed to a lack of federal testing standards as a core issue.
“The market tends to be driven by a desire for higher potency,” Tvert said. “Companies are incentivized to submit for testing the part of the plant that is most likely to have the highest level potency.”
This kind of testing habit, along with inconsistent lab rules, helps explain why THC levels on Colorado Cannabis labels often show the highest numbers possible rather than the average content found in typical consumer experiences.
State Regulators Respond to Study
The Colorado Marijuana Enforcement Division acknowledged the study and said it is reviewing the data and may hold public discussions with licensed businesses and other stakeholders.
“We look forward to an opportunity to discuss the findings of the study in a public forum,” the agency said in a statement.
Concerns about cannabis potency aren’t new in Colorado. Health experts have warned for years about the potential risks of high-THC products, particularly for adolescents. While this new study suggests the average consumer may be getting less THC than advertised, the products remain far stronger than cannabis sold in the 1980s, which averaged around 8% THC.
Testing Gaps Extend Beyond Potency
Justin Singer, founder of a marijuana edibles company and an advocate for better lab oversight, conducted a smaller potency audit earlier this year with similar results. He said the new CU Boulder study reinforces his concerns about how Colorado’s testing system is working, or not working, for consumers.
“Testing inaccuracy is testing inaccuracy. There are so many loopholes written into these rules,” Singer told CPR.
Singer warned that potency mislabeling is just one part of the problem. Pesticide contamination, mold, and other safety hazards may also go undetected under the current rules.
Giordano said CU researchers will follow up with future studies examining cannabis edibles and potential contaminants in products sold statewide.
Conclusion
As the first major peer-reviewed study to take a deep look at Colorado cannabis labels, CU Boulder’s findings highlight significant inconsistencies in how THC potency is reported. With nearly half of tested flower products overstating their strength, the study highlights some bigger problems with how cannabis potency is tested, shared, and sold in Colorado’s legal market.
It also raises serious questions about transparency, accountability, and consumer trust. As the cannabis industry matures, the demand for honest labeling and consistent lab standards will only grow louder.
This article is based on publicly available legislative records, court filings, industry reports, and published research as of the publication date. Cannabis laws and regulations change frequently — verify current rules with your state’s regulatory agency.
