THC in Hemp Foods and Cosmetics: The Appropriate Risk Assessment

By James Geiwitz, Ph.D.,
and the Ad Hoc Committee on Hemp Risks

January 15, 2001


     In 1998, industrial hemp became a legal crop in Canada, promising environmentally-sound farming and processing of fibre for paper, textiles, and building products. In addition, hempseed is among the world's most nutritious foods, and its oil is an exceptional bodycare emollient.

     In 1999, Health Canada issued a draft report entitled Industrial Hemp Risk Assessment. The report dealt only with hemp foods and cosmetics (bodycare products) and focused on tetrahydrocannabinol (THC), the psychoactive ingredient in cannabis hemp. By law, hemp foods and cosmetics must contain less than 10 parts per million THC. Health Canada concluded that, even with THC content limited to 10 ppm, "inadequate margins of safety exist between potential exposure and adverse effect levels for cannabinoids in cosmetics, food, and nutraceutical products made from industrial hemp."

     Health Canada, therefore, is considering a ban on hemp foods and cosmetics.

     The purpose of the Ad Hoc Committee on Hemp Risks is to respond scientifically to the Health Canada risk assessment. We focused on four allegations by Health Canada: acute neurological effects and toxic effects on brain development, reproductive system, and immune system. In contrast to the Health Canada conclusions, we found absolutely no health risks from the extremely low doses of THC present in hemp foods and bodycare products. In fact, the best research indicated some health benefits of THC, most notably in the strengthening of the human immune system.

     How can it be that scientists at Health Canada review the research literature on the effects of THC and conclude that hemp foods and cosmetics are unsafe, while another group, our Ad Hoc Committee, reviews the same research and concludes the exact opposite? In our analysis of the science of THC risk assessment, we identified the major problems with the research referenced by Health Canada, including extreme dosing, inappropriate extrapolation to humans from animal studies, and political pressures on scientific disinterest. Also, contrary to assumptions made by Health Canada, children are at less risk from THC than adults; hemp THC must be heated to be biologically active (which means the THC in cold pressed hemp oil is inactive); and only two or three cannabinoids are candidates for investigation in hemp foods, not 66.

     We next calculated, from our data, the appropriate standards for THC in hemp foods and cosmetics. Although there are no health risks from THC, we set the standard at the threshold for psychoactive effects, with a safety factor of 10. Scientifically determined, the maximum THC in hemp oil (the most efficient carrier) should be set at 20 parts per million - a conservative estimate, with other studies recommending limits as high as 50 ppm. Current Canadian regulations,which set the standard at 10 ppm, represent a difficult but achievable practical limit for bulk hemp manufacturers.

     Finally, to complete a cost/benefit analysis, the health benefits of Hemp foods and cosmetics were explored. In foods, the essential fatty acids (EFAs) and the high level of protein make hemp nuts an exceptionally nutritious food; a healthy heart is perhaps the most well-documented benefit. The EFAs and the protein are basic building blocks of the body, involved in health at the cellular level. The same EFAs are the primary ingredient in hemp bodycare products, which heal and nurture the skin and prevent infections.

We conclude that a ban on hemp foods and cosmetics would be ill-advised policy based on a flawed review of the research literature. Rather than protecting the health of Canadians, such a ban would be damaging. We propose instead that current THC regulations be retained, and the health benefits of hemp foods and cosmetics be the topic of Health Canada reports on industrial hemp.

Contact: James Geiwitz, Ph.D.,, 250-598-4075

Download (Adobe PDF) Report Here

Download (Word doc. Report) Here.

Ad-Hoc Committee Members

Jim B. Marc Alfred, Ph.D., Professor of Biological Anthropology (emeritus), University of British Columbia, Vancouver, BC

Jace Callaway, Ph.D., Department of Pharmaceutical Chemistry, University of Kuopio (chemistry of hemp foods), Kuopio, Finland

Paul Consroe, Ph.D., Professor of Pharmacology and Toxicology, University of Arizona (research on cannabis and cannabinoids; founding member of the International Cannabinoid Research Society), Tucson, Arizona, USA

Jozsef A. Durgo, Ph.D., D.Sc., Hemp Scientific International, Richmond, BC

Jason Freeman, President of BioHemp Technologies Ltd. (hemp food research), Regina, Saskatchewan

James Geiwitz, Ph.D., Director of Research, Transglobal Hemp Products (experimental design and analysis), Victoria, BC

Franjo Grotenhermen, M.D., nova Institute; chair, International Association for Cannabis as Medicine (toxicology of THC in hemp foods), Hurth, Germany

David Hadorn, M.D., health research (pharmacology and toxicology of hemp), Victoria, BC

Arthur Hanks, Editor, The Hemp Report , Regina, Saskatchewan

Eric Hughes, President of Zima Foods (hemp food research), Victoria, BC

Peter Kendal, C.Eng., M.I.Mech.E., formerly Engineering and Administration Manager, Omega Biotech Corporation (a nutraceutical company), Vernon, BC

John P. Morgan, M.D., Professor of Pharmacology, CUNY Medical School, New York, NY, USA

David W. Pate, Ph.D., M.Sc., Senior Technical Officer, HortaPharm BV (botany and chemistry of cannabis), Amsterdam, The Netherlands

Chuck Schom, Ph.D., New Brunswick integrated hemp industry (hemp genetics and agriculture), St. Andrews, NB

Phil Warner, Managing Director and Chairman of the Board of Australian Hemp Resource and Manufacture (AHRM), Brisbane, Australia