Can Weed Labels Be Trusted? Study Shows It Depends on What You’re Buying

*BOULDER, Colo.* – Nearly half of cannabis flower products are inaccurately
labeled when it comes to potency, with most showing they contain more THC
than they really do. Meanwhile, labels on cannabis concentrates like oils
and waxes tend to be accurate, with 96% shown to match what’s inside.

That’s the takeaway from a sweeping new analysis of products sold at
dispensaries across Colorado — the first state to legalize recreational
marijuana.

The study, published this month in the journal Scientific Reports, is the
first comprehensive label audit of legal market cannabis to date, providing
insight into just how strong cannabis has become, what the burgeoning
industry is getting right in terms of testing and labeling and where it can
improve.

“Cannabis use has complex and wide-ranging effects, and we are working hard
to better understand them,” said senior author Cinnamon Bidwell, associate
professor of psychology and neuroscience and co-director of the Center for
Health and Neuroscience, Genes and Environment (CU Change). “While that
research plays out, we should, at the very least, be providing accurate
information about the amount of THC in these products.”

The study was funded by the Institute of Cannabis Research, the state’s
official cannabis research institute, and conducted in collaboration with
MedPharm Research, LLC, a cannabis manufacturer and cultivator that holds
state and federal licenses to conduct cannabis research.

“We want to instill and foster trust in products, and the only way to do
that is to continually evaluate and correct any issues that might be
discovered,” said Duncan Mackie, director of pharmacology at MedPharm and a
co-author on the paper.
Stronger cannabis, problematic labels

Under federal law, university scientists are not allowed to purchase or
handle legal market cannabis for research, so collaborating with industry
is critical, said first author Gregory Giordano, professional research
assistant in the Department of Psychology and Neuroscience.

For the study, a secret shopper from MedPharm traveled the state to obtain
277 products from 52 dispensaries across 19 counties.

The sampling included 178 flower products (loose flower and pre-rolled
joints) and 99 smokable concentrates — everything from vials of distilled
liquids to balls of Moroccan hash and gobs of waxy “sugar.” No edibles were
included in this phase of the study.

The shopper shared label photos with Bidwell’s team. Then the samples,
marked only with a number, were tested by MedPharm chemists who hadn’t seen
the labels.

Data analysis showed that flower products contained on average about 21%
THC, or tetrahydrocannabinol — the main psychoactive ingredient in
cannabis. Concentrates contained 71% THC on average, with some containing
as much as 84%.

In the 1980s, the typical THC content in marijuana was around 8%.

“THC content has increased significantly, and we know that greater THC
exposure is likely associated with greater risks, including risk of
cannabis use disorder and some mental health issues,” notes Bidwell.

Products were considered “accurately labeled” if they contained within 15%
of the THC amount shown on the label—the same threshold the state uses.
About 44% percent of flower products failed to meet that standard, with 54
of those products inflating their THC content on the label and 23
containing more THC than the label indicated.

Either is concerning, the researchers say.

For those using cannabis medically, adequate dosing can be critical. For
those using cannabis recreationally, taking more than expected can be
dangerous.

Some discrepancies were large — one flower product was labeled as having
24% THC but had only 16%. But on average, the difference between labeled
and observed THC was about 2%.

Only four concentrate products were labeled inaccurately.

“When it comes to concentrates, I would say Colorado gets a good grade for
labeling accuracy, but there are some real issues with flower,” said
Bidwell.

Previous research in other states has shown that third-party testing labs
often inflate THC potency, possibly to gain the business of marketers
wanting to attract consumers seeking stronger products.

However, there are other potential explanations for the discrepancy:
Concentrates are often made from homogenous oils that are easier to
analyze, whereas plants are inherently heterogenous and harder to test.

Small changes in testing protocols could reduce mislabeling, the
researchers said.
Beyond THC and CBD

The study also looked at several other cannabinoids (active compounds found
in the Cannabis sativa plant), including cannabidiol (CBD), cannabigerol
(CBG), and cannabigerolic acid (CBGA). Colorado law requires that companies
put CBD levels on the label, a standard that 80% to 85% of products met.

But only 16% of products featured any information at all about other
lesser-known cannabinoids.

Notably, CBG and CBGA, which have been associated with anti-inflammatory
and anti-anxiety properties, was more abundant than CBD in products across
categories.

“Focusing on THC on the label can actually do a disservice for consumers,
because it creates an environment in which people buy based solely on THC
content,” said Bidwell. “Our data suggests that multiple other cannabinoids
should also be reported on there.”

What’s next? With support from the Institute of Cannabis Research, Bidwell
and Mackie plan to look at, among other things, labels for cannabis edibles.

As more states legalize the plant for medicinal and recreational uses, they
hope their research can inform how states regulate it.

“We all want the same thing,” said Mackie, “a strong, successful industry
that regulators can feel good about, businesses can thrive in, and
customers can trust.”