Hemp v. marijuana: TBI strains resources to tell the difference


KNOXVILLE, Tenn. (WJHL)– They look the same. They smell the same. But one of them is illegal in Tennessee.

An expert panel from the Tennessee Bureau of Investigation said differentiating between hemp and marijuana is one of the biggest challenges facing law enforcement right now.

“We at the crime lab have provided samples to canine handlers for them to experiment with and they confirmed what they feared,” said Mike Lyttle, assistant director of the TBI’s Forensic Services Division. “Their dogs simply cannot tell the difference between hemp and marijuana.”

But don’t blame the dogs.

Hemp and marijuana come from the same plant, Cannabis sativa. Marijuana has more concentrated levels of the psychoactive component THC. Anything with 0.3% THC or less is considered hemp.

Lyttle said the only way to tell the difference is with chemical testing.

“We’re having to do far more complex testing than we once did,” he said.

Special Agent Forensic Scientist Supervisor Michael Bleakley, who oversees the TBI’s lab in Knoxville, said hemp and marijuana plant samples were indistinguishable using the color test they had been performing for years.

He said the lab implemented a new version of that test about a month ago that can make a “presumptive” identification.

The TBI is using two more tests for the first time. Threshold testing, used by the Drug Enforcement Agency, can determine if a sample is greater or less than 1.0% THC. Quantitative analysis is even more granular, allowing agents to determine a percentage between 0.1% and 1%.

Bleakley said the lab is also trying to deal with a relatively new trend: an increase in THC vapes.

“We’re seeing shipments coming in here as high as 99 percent THC, those are incapacitating,” said Tommy Farmer, special agent in charge over the Tennessee Dangerous Drug Task Force.

Bleakley said vape cartridges are even more complicated to test, in part because oils can’t be color tested like plant samples.

TBI lab data shows marijuana has been the most tested substance statewide in 2019 at 10,592 cases. Methamphetamine is a close second at 10,344. Next is cocaine at 1,838.

While marijuana case counts have been relatively consistent over the years, Lyttle said the new tests are time-consuming, taking days as opposed to minutes.

He said that’s straining lab resources at a time where overall drug cases are surging.

“We are a lab that is staffed to do about 22 to 23 thousand cases a year. We are going to get probably 34 thousand cases in this year, that’s a 50 percent increase,” he said. “In order to do 50 percent more testing we’re going to need more people, more equipment and potentially more laboratory spaces.”

Lyttle said the TBI is trying to improve cooperation with District Attorney’s offices to cut down on unnecessary tests.

Officials are also encouraging local law enforcement agencies to use field testing.

Bleakley said that too comes with barriers.

“It’s brand new, it’s not widely available. I believe there are only one or two places that even sell this test kit and obviously everybody wants them,” he said. “In addition, they cost money so that is another expense for local law enforcement and more training.”

Lyttle said legalizing marijuana could create more unintended consequences for law enforcement, like driving under the influence. He said 40 to 45 percent of the drug screens they perform test positive for marijuana.

Lyttle said he’d like to see more regulations on the hemp industry, like requiring licensed growers to show proof of certification and setting clearer rules for transporting the product.

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