Marijuana product labels fail to capture “the chemical reality” of what people smoke, a University of Colorado study has concluded after analyzing 90,000 samples offered for sale in six states.

The widely used labeling system purported to predict effects of different “strains” – “indica” (relaxed high), “sativa” (energetic high), and “hybrid” – obscures the diversity of chemicals cannabis consumers inhale, according to the study, which was published Thursday in the online science journal PLOS One.

CU information scientists analyzed labels that companies provided for an online platform called Leafly, which lets consumers see a more complete listing of contents in marijuana products.

They compared this labeling with the commonly used system.

“The prevailing labeling system is not an effective or safe way to provide information about these products,” said University of Colorado information sciences professor Brian Keegan, who co-authored the study with Daniela Vergara, now at Cornell University.

For example, imagine a woman walking into a liquor story to buy a bottle of wine labeled Cabernet who then finds it to be Pinot Grigio.

“You would, justifiably, be upset,” Keegan said. “In the cannabis industry, those kinds of mismatches can happen frequently.”

The researchers recommend creation of a standardized “weed labeling system” similar to the U.S. Food and Drug Administration’s nutrition facts labels on food products.

Their study stands out as perhaps the largest so far exploring the chemical composition of marijuana products. A decade after marijuana legalization in Colorado, product labeling has emerged as an issue amid a push by companies for greater professionalization.

Marijuana products heavily marketed to consumers contain dozens of chemical compounds with potential psychoactive or medicinal effects. CU’s researchers contend understanding these chemicals is crucial.

Government regulators of the industry in Colorado and other states where marijuana has been legalized require companies to disclose dosages of the psychoactive THC (tetrahydrocannabinol) and CBD (cannabidiol) chemicals. This focus led to wide use of the indica, sativa and hybrid labels to distinguish different strains offered to consumers.

“But that’s not the most important thing about the cannabis that is consumed. There’s a whole set of chemicals, beyond THC, that explain why different strains are different and why people might experience different effects,” Keegan said.

Companies aren’t obligated to list compounds such as terpenes and flavonoids that play a greater role determining taste, smell and effects. The CU researchers concluded marijuana strains more accurately could be distinguished using different categories. One could encompass products high in terpenes called caryophyllene and limonene, the researchers said. Another group could contain elevated myrcene and pinene. Another could be categorized for high terpinolene and myrcene.

Groups including the Institute for Safe Medication Practices previously have called for national regulation of medical marijuana labeling to ensure states can protect consumers.

“If you were trying to make dietary decisions using labels that only listed calories and fat, that would hamper your dietary decisions,” and the current labeling of marijuana products “is a profound disserve to consumers,” Keegan said.

“It is a cause for concern, particularly if you are treating this plant as a medicine,” he said. “It would be great to have labels that convey the whole rainbow of chemicals that are present in cannabis.”