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Home > Articles > Science & Health > Content Piece

Unrepresentative Cannabis Samples Could be Holding Back Research

by Mike May
Published: Aug 14, 2017   
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To study cannabis in the United States, a researcher get samples from the U.S. National Institute on Drug Abuse (NIDA), but those leave a lot to be desired. “This material is much less diverse than what is available in the state markets, and has much lower levels of tetrahydrocannabinol, THC, and other cannabinoids,” says Nolan Coburn Kane, assistant professor of ecology and evolutionary biology at the University of Colorado Boulder. As he and his colleagues reported: “Most dramatically, NIDA’s varieties contain only 27% of the THC levels and as much as 11–23 times the Cannabinol (CBN) content compared to what is available in the state-legal markets.”1 Kane adds, “Other studies have shown high levels of mold as well.” That means that anyone doing research on cannabis is working on something that might differ from what   consumers purchase, and possibly even contaminated samples. 

The quality of the NIDA cannabis also depends on growing and storage conditions. The NIDA website states that its crops “are grown every few years.” And Kane points out that NIDA cannabis samples appear “to be stored in conditions that lead to deterioration over this time frame.” 

The root of the problem

To understand why the variation between federal samples and the street matters, we need to consider the purpose of the research. “The material used in federally approved research is typically intended to address very broad questions about the health benefits and/or risks of marijuana use, and the physiological, neurological and psychological effects of cannabis and derived compounds,” Kane explains. “However, because cannabis is a diverse plant with hundreds of potentially important bioactive compounds, it is hard to make broad conclusions while only using one or a few strains.”

The NIDA samples do not replicate what is available on the market, which “means that the studies done in the U.S. to date are only relevant to understanding the effects of very low quality, poorly stored marijuana and may not necessarily reflect the effects of the diverse and higher quality material more typically used by people who purchase material in the state legal markets,” Kane says. So, no one can make accurate predictions about the impacts of products or medicines when the research is not on similar materials. For one thing, says Kane, this “calls into question some of the sweeping conclusions made by many published research articles and reviews.” He adds, “Some of the health risks reported, for instance, may be due to mold or other contaminants and breakdown products, while the lack of support for some currently widespread medical uses may be due to the lower quality of the material used in research.”

What to do

With the problem identified, the next step is: How can this be addressed? In short, the samples for testing need to be improved. “Researchers need to use material that is much more similar to what is available in the state markets, and more needs to be known about the importance of terpenoids and more minor cannabinoids, which appear to interact with THC to create the complex and diverse effects of marijuana,” Kane explains.

So far, scientists don’t even know the complete range of what research samples should cover. As Kane and his coauthors noted: “Investigation is urgently needed on the full diversity of Cannabis chemotypes known to be available to the public.”

In short, some research must be done and federal rules adjusted. Translation: It won’t happen overnight. 


1. Vergara, D., Bidwell, L.C., Gaudino, R. et al. Compromised external validity: Federally produced cannabis does not reflect legal markets. Sci. Rep. 2017 (doi: 10.1038/srep46528).


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