What is THC-O? Similar to Delta-8, it's making waves in the cannabis market

A growing number of marijuana-adjacent products are hitting consumer markets in the United States. Among them is a synthetic cannabinoid known as THC-O.

The passage of the 2018 farm bill legalized hemp and spawned a cottage industry of weed look-alikes that are similarly intoxicating – and legal.

“These hemp-derived intoxicants came into the marketplace through the back door and now states are trying to figure out how to respond," Chris Lindsey, director of state campaigns and public policy at the American Trade Association of Cannabis and Hemp, told USA TODAY.

But, does THC-O fall into that bucket?

It's complicated.

Here's what you should know about the newly popular cannabinoid.

What is THC-O?

THC-O most commonly refers to THC-O acetate, a synthetically sourced cannabinoid. Cannabinoids are a set of related chemical compounds sourced from cannabis.

THC-O has created buzz in recent years as a relatively "new" cannabinoid on the market, joining ranks with Delta-8 and Delta-10. Like other cannabis products, it is available from various hemp sellers in the form of vape cartridges or edibles like gummies.

Derived from hemp, the chemical compound is entirely synthetic, meaning it cannot be found naturally in the plant.

Calling THC acetate a cannabis product is a bit of a misnomer, though, said Daniele Piomelli, a professor of anatomy and neurobiology and the director of the Center for the Study of Cannabis at the University of California, Irvine.

That's because producers create THC-O by taking CBD and converting it to Delta-8 or Delta-9, then combining it with another chemical, to get the final result, he said.

What is Delta-8? Here's what to know about the 'diet weed.'

Is THC-O legal in the US?

The chemical compound is technically derived from the hemp plant, so some sellers have assumed THC-O to be legal under the 2018 farm bill.

However, the U.S. Drug Enforcement Administration warned in February that both Delta-8 THC-O and Delta-9 THC-O are illegal controlled substances because they do not occur naturally and thus do not fall under the legal definition of hemp, the DEA said.

Is Delta-8 legal? Here's where (and why) the hemp product skirts marijuana laws.

What is the difference between THC-O and regular THC?

Regular THC can be found naturally in the cannabis plant, while THC-O is synthetically produced.

“Ingenuity never stops so they came up with this idea of adding an acetate to the chemical functionalities of the THC molecule,” Piomelli said.

The chemical reaction makes it so the cannabinoid is not able to bind to the receptors in the brain usually responsible for that "high" feeling, he said. However, that chemical modification allows the compound to more easily get into cells and the brain, and once it enters the brain, the acetate should wear off and the remaining THC can attach to the correct receptors, Piomelli said.

There is very little research into THC-O, he said. And if the acetate does not wear off, there is a danger of having it float around the body and potentially cause harm.

Is THC-O more potent, or stronger than Delta-9 THC?

Delta-9 THC is the psychoactive component in marijuana responsible for the “high” feeling users get when they smoke or ingest it. When people refer to "pot" or "weed," they are likely referring to Delta-9 products.

There is very limited peer-reviewed research on the potency of THC-O as it compares to naturally occurring compounds, but users report anecdotally that it gives a more extreme high than regular Delta-9 THC.

The High Times, a publication about hemp and marijuana news, refers to the compound as the "psychedelic cannabinoid," and purports it is three times as intoxicating as Delta-9. That number, though reported in a number of articles online, is not linked to official data. It appears to come from the 1977 book, "Marijuana Chemistry: Genetics, Processing, Potency" by Michael Starks.

“There is very little reviewed research done on THC acetate," Piomelli said, "and partly this is due to the fact that it’s a new invention of crafty entrepreneurs who like to circumvent the controlled substance act.”

His worry is that the science will not catch up in time.

"By the time we have data on THC acetate, the harm will already be done,” he said.

In what states is weed legal? Here is the list.

This article originally appeared on USA TODAY: What is THC-O? What to know about potency, legality, more