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Cannabis Cannabinoid Res. 2017 Oct 1;2(1):274-281. doi: 10.1089/can.2017.0040. eCollection 2017.

Cannabis sativa (Hemp) Seeds, Δ9-Tetrahydrocannabinol, and Potential Overdose.

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Center for Molecular Design and Preformulations, Toronto General Hospital Research Institute, University Health Network, Toronto, Canada.
Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada.
Multi-Organ Transplant Program, Toronto General Hospital, University Health Network, Toronto, Canada.
Department of Anaesthesia, Faculty of Medicine, University of Toronto, Toronto, Canada.
The Pain Research Unit, Department of Anesthesia and Pain Management, Toronto General Hospital, University Health Network, Toronto, Canada.


Introduction:Cannabis sativa (hemp) seeds are popular for their high nutrient content, and strict regulations are in place to limit the amount of potentially harmful phytocannabinoids, especially Δ9-tetrahydrocannabinol (Δ9-THC). In Canada, this limit is 10 μg of Δ9-THC per gram of hemp seeds (10 ppm), and other jurisdictions in the world follow similar guidelines. Materials and Methods: We investigated three different brands of consumer-grade hemp seeds using four different procedures to extract phytocannabinoids, and quantified total Δ9-THC and cannabidiol (CBD). Discussion: We discovered that Δ9-THC concentrations in these hemp seeds could be as high as 1250% of the legal limit, and the amount of phytocannabinoids depended on the extraction procedure employed, Soxhlet extraction being the most efficient across all three brands of seeds. Δ9-THC and CBD exhibited significant variations in their estimated concentrations even from the same brand, reflecting the inhomogeneous nature of seeds and variability due to the extraction method, but almost in all cases, Δ9-THC concentrations were higher than the legal limit. These quantities of total Δ9-THC may reach as high as 3.8 mg per gram of hemp seeds, if one were consuming a 30-g daily recommended amount of hemp seeds, and is a cause for concern for potential toxicity. It is not clear if these high quantities of Δ9-THC are due to contamination of the seeds, or any other reason. Conclusion: Careful consideration of the extraction method is very important for the measurement of cannabinoids in hemp seeds.


Cannabis sativa seeds; cannabidiol; hemp seeds; overdose; phytocannabinoid extraction; tetrahydrocannabinol

Conflict of interest statement

L.P.K. and H.A.C. serve on the scientific and medical advisory board of Scientus Pharma, Inc. and receive a consulting fee.

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