Colorado weed products are weaker than advertised, new study finds

A new study of Colorado marijuana dispensaries has shown that the THC levels advertised may not be entirely accurate.
Christopher McFadden
It appears, weed consumers in Colorado are being mislead.


A new study published in PLOS-One found that cannabis products may be much weaker than advertised. In the study, researchers from the University of Northern Colorado found that cannabis products sold in authorized dispensaries in Colorado (one of America's twenty-one states that have legalized the recreational use of marijuana) often had much lower THC levels than the labels indicated.

In case you are unaware, THC, or delta-9-tetrahydrocannabinol, is the main active ingredient in cannabis that causes consumers to "get high." According to the study, the THC potency of cannabis used for recreational purposes has progressively risen over the previous few decades. However, there has also been concern that businesses have been exaggerating the THC content of their products to increase their popularity and cost.

One popular technique for doing this, Gizmodo reports, is called "lab shopping," in which businesses send their products to various labs for analysis and only choose the results that look best on their label. People have begun to hold particular companies responsible for these actions; some have even been sued. However, there hasn't been a lot of information on how widespread this might be in the industry.

To test commercial THC levels, the team bought 23 samples covering around 12 strains of cannabis from 210 dispensaries across the states. They then tested the samples in a third-party laboratory. Overall, it was discovered that the samples contained much less THC than what was stated on the label. Three samples had THC levels that were half as low as the maximum potency they were supposed to have, and almost 70 percent of the samples had THC levels that were over 15 percent lower than advertised. About 60 percent of the samples had a range rather than a single number indicating the THC strength on the label. However, labeling even these samples frequently showed signs of a labeling error.

“Our results demonstrate that retail cannabis flower THC potency is significantly inflated in samples purchased in Colorado. Given the numerous recent reports and lawsuits questioning THC potency reporting, it is likely that this is an industry-wide problem,” the authors wrote.

All very interesting, but it is important to note that this is just one study with a relatively small sample size. Some study authors also acknowledged financial ties to the cannabis industry, including two working for the independent lab that conducted the study's testing.

The authors claim that, except for paying some of them a salary, none of their employers had any involvement in the research and that even hypothetical conflicts of interest do not make a study's findings worthless. But these qualifications highlight the need for additional research from other teams to support the results and better comprehend the magnitude of this possibly pervasive issue in the sector.

“Although we have no power to change the current system, we hope highlighting this issue and educating consumers will affect the change needed to remedy the inflated potency of flower products,” the authors wrote. “Addressing this discrepancy will require changes to the regulatory system and consumer awareness that reported THC potencies are frequently inflated,” they added.

You can view the study for yourself in the journal PLOS-one.

Study abstract:

"Legal Cannabis products in the United States are required to report THC potency (total THC % by dry weight) on the packaging, however concerns have been raised that reported THC potency values are inaccurate. Multiple studies have demonstrated that THC potency is a primary factor in determining pricing for Cannabis flower, so it has an outsized role in the marketplace. Reports of inflated THC potency and “lab shopping” to obtain higher THC potency results have been circulating for some time, but a side-by-side investigation of the reported potency and flower in the package has not previously been conducted. Using HPLC, we analyzed THC potency in 23 samples from 10 dispensaries throughout the Colorado Front Range and compared the results to the THC potency reported on the packaging. Average observed THC potency was 14.98 +/- 2.23%, which is substantially lower than recent reports summarizing dispensary reported THC potency. The average observed THC potency was 23.1% lower than the lowest label reported values and 35.6% lower than the highest label reported values. Overall, ~70% of the samples were more than 15% lower than the THC potency numbers reported on the label, with three samples having only one half of the reported maximum THC potency. Although the exact source of the discrepancies is difficult to determine, a lack of standardized testing protocols, limited regulatory oversight, and financial incentives to market high THC potency likely play a significant role. Given our results it is urgent that steps are taken to increase label accuracy of Cannabis being sold to the public. The lack of accurate reporting of THC potency can have impacts on medical patients controlling dosage, recreational consumers expecting an effect aligned with price, and trust in the industry as a whole. As the legal cannabis market continues to grow, it is essential that the industry moves toward selling products with more accurate labeling."

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