Medical marijuana canisters at a Denver, Colorado, clinic
Matthew Staber/Bloomberg via Getty Images
In a small sample of marijuana sold legally in Colorado, most products contained significantly more tetrahydrocannabinol (THC), the plant’s main psychoactive ingredient, than stated on the package. It turns out less.
“We know it’s happening, everyone’s talking about it, but nobody’s putting scientific rigor behind it.
She and her colleagues obtained 23 samples from 10 Colorado clinics and tested them for THC levels in a private lab. Colorado, like other U.S. states that have legalized recreational marijuana, requires pharmacies to label their products with potency ranges based on tests from third-party laboratories.
They found that the samples were on average 23% less potent than the lower end of the labeled range. More than half of the samples were 30% or more less potent.
“People pay for the product, but they don’t get it,” says Schwabe. For medical marijuana users, this could mean someone isn’t getting the right dose, she says.
Sampling different parts of the plant and using different test equipment and methods can lead to discrepancies, said Erik Paulson of Infinite Chemical Analysis Labs in California. But he says labs have a clear motive for overestimating potency. You can choose any lab that gives you numbers, he says.
In 2022, Paulson’s company analyzed more than 150 samples from California dispensaries and found that nearly all had potencies that differed from the label by 10% or more. He says that reporting accurate and ineffective results has caused his company to lose customers. “Every producer knows which lab to go to.”
Stephen Goldman of Kaycha Labs, a national testing company, says potency is particularly appreciated in new markets such as California, Oregon and Michigan, and the Colorado results don’t surprise him. “In general, can labs do better? Absolutely,” he says.
new scientist We contacted three clinics where samples were believed to have been obtained based on the license numbers listed in the survey. Two did not respond and one declined to comment.
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