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Delta-8 vs delta-9 THC – what’s the difference?

Researchers in the US have been investigating whether the effects are the same.



Delta-8-THC is legal in some states in the US.Photo: Elsa Olofsson/Unsplash

Amid its growing popularity, researchers in the US have been investigating whether the effects of delta-8 THC are the same as delta-9 THC – the psychoactive compound naturally found in cannabis.

One is an illegal compound found in the cannabis plant, while the other is found in some US states being marketed as a safe herbal alternative. 

But the claimed differences between them aren’t backed by science, according to a new paper by a group of researchers in the US. 

What’s the difference between delta-8 and delta-9 THC?

Tetrahydrocannabinol, or THC, is the psychoactive compound produced by cannabis plants. 

The federal government lists Δ9 -THC (pronounced delta-9-THC) on the Schedule one list of dangerous drugs with no accepted medical use. 

But other versions of THC that differ only by the location of a double bond, such as Δ8-THC, remain quietly quasi-legal at the federal level.

The legality differences between the various versions of THC are causing conflict between the hemp and cannabis industries. There is also potential for harm to consumers. 

Although delta-8 THC is viewed as an herbal extract of hemp, many manufacturers use solvents and chemical processes that can leave harmful residues in the product, and there are no standards for purity or safety. 

READ MORE: Cannabis vs synthetic cannabinoids – the difference is deadly

Because there are no limits, some products contain extremely high levels of delta-8 and other THC variants that could potentially cause harm due to the dosage. 

Some states in the US, such as Connecticut, have made delta-8-THC as controlled as delta-9 THC, while in others it remains legal. 

Delta-8 THC is illegal in the UK. 

According to the UK Home Office: “Delta-8 THC is a cannabinol derivative that is controlled as a Class B drug under the Misuse of Drugs Act 1971. This means it is illegal to possess, sell or produce with a maximum penalty for supply of 14 years or a fine or both.”

What the science says

Most people who have experience with both agree that the effects are similar.

However, researchers associated with the University of Connecticut wanted to see if the science backed this up.

Research done in Japan in the 1980s had previously shown that delta-8THC produced the same effects in mice as delta-9 THC. 

University of Connecticut School of Nursing professor and Center for Advancement in Managing Pain director, Steve Kinsey, and graduate student Olivia Vanegas, reproduced this work and also found it to be true. Their findings were published in the journal, Drug and Alcohol Dependence.

When the mice given Delta-8 became lethargic, their body temperature dropped, and they became cataleptic, meaning the researchers could put the mice in unusual positions and they would stay like that for several seconds.

This is common in mice which have been treated with THC, but not normal mice.

Then the researchers took it a step farther, blocking the mice’s THC receptors. Blocked mice had no reaction to delta-8 THC, making it clear that delta-8 interacts with the same receptors as delta-9.

The researchers then took a group of mice and gave them delta-8-THC twice a day for five days. 

Over time, the mice became desensitised to it, and when they were then given the THC blocker, they displayed symptoms of withdrawal.

Finally collaborators at RTI International ran an experiment ‘asking’ the mice how the drug felt. 

The mice were trained to go to a specific spot for a reward if they were dosed with delta-9-THC. After the training, the mice were dosed with delta-8-THC. 

Unsurprisingly, they went to the same reward spot as when they were dosed with delta-9.

Kinsey said: “They’re telling us the same thing people buying the stuff in gas stations tell us: delta-8 feels like THC.”

Chemically, it’s unsurprising. Molecules as similar as delta-8- and delta-9-THC usually (though not always) act the same in the body. 

A legal loophole?

But in the US, the similarity is causing legal complications.

The distinction between delta-8 and delta-9 originally came about from the congressional Farm Bill covering hemp growing and sales. 

Hemp is defined as a cannabis plant that has less than 0.3% delta-9-THC by dry weight. 

Anything that has more concentrated delta-9-THC than that is considered ‘marijuana’. Additionally, the Farm Bill said anything else naturally present in the hemp plant is legal. That includes delta-8-THC.

John Harloe, an attorney on Colorado’s THC taskforce, said: “It’s creating a fight between marijuana and hemp growers.”

Products classified as ‘marijuana’ “must be sold through dispensaries and pay high taxes, while hemp producers can sell essentially the same product but without the same regulations, due to the ambiguity in the Farm Bill,” Harloe says.

The THC taskforce is trying to create appropriate regulation that will address the different chemical variations of THC and guard public safety without crippling the hemp industry. 

The paper is particularly valuable because there is so little research done on THC and its intoxicating effects, due to federal rules.

Harloe adds: “Any bit of science is going to be influential.”


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