Many hemp-labeled THC edibles may not come from legal hemp

Δ9-THC edibles are widely marketed as federally compliant industrial hemp under the 2018 Farm Bill (≤0.3% Δ9-THC by dry weight). We evaluated whether the labeled Δ9-THC content in edibles marketed as "hemp" could be supplied using cannabis material meeting that threshold without exceeding the mass of the edible. From October 2025 to February 2026, we identified online retailers marketing Δ9-THC edibles as hemp to U.S. consumers. For each product, we examined Δ9-THC content (mg), unit weight (g), and sugar content (g) from product labels and/or laboratory reports. We calculated the minimum cannabis mass required to supply the Δ9-THC content, assuming the maximum legal concentration (0.3%). Products were classified as mathematically infeasible when required cannabis mass exceeded available non-sugar mass (primary test) or total product mass (ultra-conservative test). Prevalence estimates used bootstrap confidence intervals (2,000 replications; clustered by brand). 80% of products would have to contain mathematically impossible portions of cannabis (95% CI: 72-88%; n=297); the median product required cannabis material equal to 160% of available non-sugar mass. 2% required more cannabis than the total product mass (95% CI 0%-4%; n=380). Across all edible types, most appear unable to obtain their Δ9-THC content from lawful hemp material. Most Δ9-THC edibles marketed as "hemp" appear infeasible to manufacture using cannabis material containing ≤0.3% Δ9-THC by dry weight without exceeding the available product mass, even under highly conservative assumptions. Thus, most appear to depend on marijuana as an ingredient, which has substantial regulatory and public health implications.