Are Michigan marijuana customers being ‘ripped off’ by inflated THC potency claims?

File photo -- Lab worker demonstrates physical inspection of samples of marijuana flower on Monday, Feb. 14, 2022.The Ann Arbor News

Michigan cannabis customers enjoy strong weed, but many within the industry say high demand has led to questionable conduct by greedy marijuana growers, producers and testing labs.

Growers pressure labs for the higher potency results, and sometimes labs bend science to reach them, multiple lab representatives industry insiders have alleged to MLive.

“People are spending money every day -- $250 million a month is being spent -- and if a significant amount of that is being (potency) inflated, people are being ripped off on a massive scale,” said Avi Zallen, CEO of Steadfast Lab in Hazel Park. “I don’t know if it’s as much of a health and safety question as it is ripping off consumers.”

Related: Super potent weed spurs distrust

Because marijuana flower prices and profits are so closely linked to THC percentages -- higher the better -- reports of potency inflation have plagued nearly every legal marijuana market in the U.S.

“How fast the market has expanded, it’s an inherent problem,” said Alex Adams, CEO of Cambium Analytica, a Traverse City lab. “This is not new. We’ve known about this problem. It’s terrible in California, it’s getting worse in some of the older markets.

“If there is an incentive created at the laboratories, then people will ... use those laboratories at the expense of the customer.”

Viridis questions

One lab that has fallen under public scrutiny for suspected potency inflation in Michigan is Viridis Laboratories, founded by former State Police officers with operations in Bay City and Lansing.

By November 2020, the Cannabis Regulatory Agency (CRA) was investigating whether Viridis was reporting inflated THC potency percentages, according to court filings and testimony.

The CRA audited potency results exceeding 28% and found that nearly 80% of all tests above the threshold had been conducted by Viridis labs, according to a CRA rules violation complaint filed in May 2022. The complaint didn’t identify between what dates the data came from. The reviewed data also showed that the Virdis Lansing lab was testing marijuana above 28% at a rate seven times higher than the rest of the labs in the state, the CRA said.

“The number of flower samples that exceed 30% are coming from Viridis Laboratories, primarily,” Clair Patterson, the CRA’s science manager, wrote in a Dec. 2, 2020 email sent to Viridis management and later included in court filings.

Viridis insists its method is more accurate than other labs and points to certifications, accreditations and passed CRA audits to justify its claims.

Related: Controversial marijuana lab says results are legit

A dozen complaints filed against Viridis’ for rule violations are currently being contested in the Michigan administrative courts. Administrative Law Judge Stephen Goldstein conducted four days of testimony during hearings that were closed to the public on May 15, 16, 23 and 24. MLive has since obtained transcripts from those hearings through a Freedom of Information Act request.

They reveal what CRA investigators and analysts say Viridis was doing that might inflate THC results.

The Viridis method

Labs are required to randomly collect samples of marijuana for testing. It arrives at the lab in the form of buds with stems and other plant material. Some parts are more potent than others, so the lab puts the marijuana through a process called homogenization, essentially chopping or blending the marijuana so that it’s evenly mixed.

The most potent portion is the kief or resin, described at the contested court hearing by Claire Patterson, who heads the CRA Scientific Section, as the accumulation of loose “glandular hairs” with “water tower looking bulbous resin reservoirs on top of them.”

“That’s where the THC, the CBD, the various cannabinoids and terpenes are actually held,” Patterson testified. Kief contains more THC than the rest of the plant, often exceeding 50% potency.

Viridis used a method of homogenization that involved adding “ceramic grinding balls” to the plant material inside a container. A machine shakes that container at high speeds, causing the metal balls to pulverize and mix the marijuana. When completed, the balls are coated with the sticky layer of high-potency kief.

Some labs tell MLive they don’t attempt to recover the lost kief, since the loss is negligible. Others use means to retain the kief in the sample.

“We use cryogenic milling,” said Zallen of Steadfast Lab. “It’s more expensive and slower ... but we do it because we’re committed to accuracy.”

Steadfast uses liquid nitrogen to cool machinery to near -94 F. At low temperatures, the kief and resin won’t stick and remains in the sample.

Once the sample is homogenized, a smaller portion is added to another testing container and mixed with a solvent that extracts the THC for analysis in scientific machinery.

Viridis was “taking those kief-laden grinding media, dropping them into the extraction vial, and then adding a very small amount of flower,” which was much less than the amount the lab notified the CRA they were using, Patterson testified at the contested hearing in administrative court.

‘A more representative sample’

In a Dec. 3, 2020 email that was included in court exhibits, Patterson discussed the method with Viridis Chief Science Officer Dr. Michele Glinn, who said kief stuck to the grinding balls was scraped with a plastic spatula or “rinsed” into “extraction vials.”

Glinn admitted during the email conversation that this technique increases the sample potency results by “several percent.”

“The major reason you might be seeing these numbers from us is that we make a concerted effort to recover all parts of the plant, including the sticky resin,” Glinn wrote. “This gives a more representative example of the total potency of the plant material and is closer to what a customer using the product would be exposed to.”

Patterson testified that, while that may be true, Viridis hasn’t provided the necessary scientific data to prove it doesn’t bias results.

Elevated potency test results present a clear competitive advantage for Viridis, some competing labs say.

“We’ve had customers that have walked away from us, that said, well, your number isn’t as high as Viridis,” said Bob Miller, the chief science officer for Act Lab, which operates in Lansing and five other states. “So, therefore, we’re not going to do business anymore. We’ve definitely lost customers because of that.”

Patterson testified the Viridis method has never been approved by the CRA. It has been certified by the Association of Official Agricultural Chemists’ (AOAC) International Reviewed and Recognized program. The AOAC is an organization of chemists that establishes standards for chemical analysis that the CRA recognizes.

AOAC representatives declined to answer MLive’s questions regarding the certification.

“We understand that there is litigation among other parties involving the matter and don’t have anything to add at this time,” AOAC spokesperson Dawn L. Frazier said.

‘Black science’

Lev Spivak-Birndorf, founder and chief science officer for Ann Arbor-based PSI Labs, said theoretically the Viridis method of reintroducing high-potency kief lost in the sample preparation process is not wrong, but the way it’s being done is unscientific.

“There is some evidence that if you add a kief-covered grinder ball to an extraction, you’re potentially disproportionately adding more kief,” which could erroneously elevate the potency results.

Miller of Act Lab said he’s heard of other testers using similar methods, “and it’s just not good science.”

“I call it black science,” he said. “It’s a separation of the higher potency THC and adding it back in a not-uniform fashion, essentially.”

The CRA didn’t reply to questions from MLive regarding why the agency, tasked with ensuring public health and safety, has since at least December 2020 knowingly allowed Viridis to use a method it disputes over accuracy. “We do not comment on pending litigation,” CRA spokesman David Harns said.

The CRA, based on Viridis testing issues unrelated to potency, issued its largest-ever recall on all Viridis-tested marijuana flower in November 2021. Viridis estimated the recall impacted 64,000 pounds of marijuana flower valued near $229 million. A large portion

Viridis attorney David Russell disputes information Patterson shared during the May court hearings.

“The latest testimony by Ms. Patterson totally mischaracterizes Viridis’s proprietary potency testing methods which the AOAC certified through an extensive process including independent laboratory evaluators and third-party reviewers as part of its Reviewed and Recognized program,” Russell said. “Viridis is the first and only cannabis testing laboratory in the world to receive certification for our potency testing methods in marijuana and the AOAC addresses our sampling process in their report on our potency certification noting that our grinding process provides a more accurate analysis of cannabis potency making it safer for consumers.

“We are confident that the continued court proceedings and evidence will further expose the true motives behind the botched recall of 2021, the CRA’s desire to cause financial and reputational harm to Viridis, and that none of the regulatory actions targeting Viridis were done in the interest of protecting the health and safety of Michigan consumers.”

The Virids-CRA contested hearings are scheduled to resume in July with hearing dates set for July 26, July 27, Aug. 23 and Aug. 24.