Researchers checked whether the THC advertised on hemp edible labels could actually have come from hemp. For four out of five products, the arithmetic doesn’t work.
A study published this week in the Journal of Studies on Alcohol and Drugs finds that 80 percent of delta-9 THC edibles sold to American consumers as federally compliant hemp “would have to contain mathematically impossible portions of cannabis.”
The title states the finding plainly: “Most Delta-9-THC Edibles Marketed as Hemp Appear to Require THC Ingredients Classified as Marijuana Under Federal Law.”
The 2018 Farm Bill legalized cannabis containing no more than 0.3 percent delta-9 THC by dry weight. Everything above that line remains marijuana, a Schedule I controlled substance. An entire retail category, sold in gas stations, vape shops and online, rests on the claim that its products sit under the ceiling.
The research team, led by Matthew E. Rossheim of the University of North Texas Health Science Center, tested that claim against the labels. From October 2025 to February 2026, they collected the advertised THC content, unit weight and sugar content for hundreds of products, then calculated the minimum cannabis needed to supply the THC on the label, assuming the richest legal hemp available at exactly 0.3 percent.
For most products, the required plant material would not fit inside the product. The median edible needed cannabis equal to 160 percent of its available non-sugar mass.
The authors conclude that most of these edibles “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.” Their finding: “most appear to depend on marijuana as an ingredient, which has substantial regulatory and public health implications.”
The industry’s standard answer is that its products test under the legal threshold, and that is generally true. A 2023 analysis in the Journal of Cannabis Research found 96.2 percent of hemp delta-9 products fell within the Farm Bill limit. But that measures concentration in the finished product, not where the THC came from. A heavy gummy can carry a large dose and still compute under 0.3 percent, which is the mechanism that created the category in the first place.
That same 2023 paper, funded by the CBD industry website CBD Oracle and written in part by authors who describe themselves as “advocates of cannabis and hemp,” reached a related conclusion from the other direction. It estimated that 49 percent of products used THC chemically converted from CBD, and that 26.5 percent used THC “sourced from cannabis.” The authors wrote that this “raises issues with the Farm Bill’s definition of ‘hemp’ in any case.”
The products are not niche. In 2023, the first year the question was asked, 11.4 percent of American 12th graders reported using delta-8 THC, a related hemp-derived intoxicant, in the past year. In August, 35 state attorneys general urged Congress to reject any effort to delay or weaken the federal hemp THC ban.
That ban takes effect November 12. The industry and its allies are pressing Congress for a delay.
The new findings complicate the premise of that fight. If most of these products were never lawful hemp, they were never inside the exemption anyone is arguing about.