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Legal marijuana in Colorado is three times stronger than it was 30 years ago

David Ramos/Getty Images

Marijuana has been legally for sale in Colorado for more than a year and researchers have for the first time taken the weed into the lab to take stock of the drug’s potency and contaminants.

“As far as potency goes, it’s been surprising how strong a lot of the marijuana is,” researcher Andy LaFrate says. “We’ve seen potency values close to 30% THC, which is huge.” THC is an abbreviation for tetrahydrocannabinol, which is the psychoactive compound in the plant.

LaFrate is the president and director of research of Charas Scientific, one of eight labs certified by Colorado to do potency testing.

Watch the video clip explaining the research:

LaFrate says that three decades ago, THC levels were well below 10%. Its content has tripled in some strains because producers have been cross-breeding over the years to meet user demands for higher potency.

As for contamination testing, some producers voluntarily submitted samples to see what’s in their products.

“It’s pretty startling just how dirty a lot of this stuff is,” he says. “You’ll see a marijuana bud that looks beautiful. And then we run it through a biological assay, and we see that it’s covered in fungi.”

The lab also finds varying levels of chemical contaminants such as butane, which is used to create marijuana extracts. Contamination isn’t necessarily a cause for alarm, but it does signal a need to figure out what levels are safe.

“It’s a natural product,” LaFrate says. “There’s going to be microbial growth on it no matter what you do. So the questions become: What’s a safe threshold? And which contaminants do we need to be concerned about?”

The results of the research will be released at the 249th National Meeting of the American Chemical Society in Denver.

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