Colorado study finds THC labels often miss actual flower potency

INTRODUCTION: High-concentration delta-9-tetrahydrocannabinol (THC) products, with limited research, are becoming accessible in a rapidly expanding cannabis market. There is concern about poor labeling accuracy for THC in recreationally available cannabis, which could impact public health and consumer safety. However, coarse and fine-grained data representative of the scope of legal-market cannabis products have not been reported. This project aimed to investigate THC labeling discrepancies in recreational cannabis flower products and extend examinations to the accuracy of representative cannabis flower subtypes commonly available in a state-legal market. MATERIALS AND METHODS: Products were purchased between November 2022 and March 2025 from 59 licensed dispensaries across Colorado and analyzed for discrepancies in labeled versus observed THC concentration (%). Cannabis flower products (N = 265) were included and further divided into pre-pack (n = 76), pre-roll (n = 27), re-pack (n = 55), and deli (n = 107) subtypes. Based on regulatory guidelines, product accuracy was determined by evaluating whether observed THC concentration (%) was within &#xb1; 15% of labeled THC concentration (%), and was further evaluated by product subtype. RESULTS: Half (51.7%) of the flower products sampled were accurately labeled. Labeling accuracy (&#x3c7;2(6) = 15.15, p = 0.02) and the percent deviation from labeled THC concentration (%) (H = 14.3, p < 0.001) depended on product subtype. Post hoc comparisons for product accuracy indicated that pre-roll products were more likely to be over-labeled (59.3%), and re-pack products had the greatest proportions of mislabeled products that were over-labeled (96.0%). Furthermore, post hoc comparisons indicated that pre-roll products had the greatest deviation from labeled THC concentration (19.6%). CONCLUSION: Consistent with previous findings, recreational flower products were inaccurately labeled for THC. While all flower product subtypes demonstrated low labeling accuracy, it was observed that products subject to greater handling by dispensaries (i.e., pre-roll and re-pack) were more prone to THC over-labeling inaccuracies. Future research should explore how these findings impact consumer trust, consumption, and purchasing habits.